Pediatric Annals

Infantile Cataracts

David A Hiles, MD

Abstract

Infantile cataracts are the most significant cause of remediable blindness in children.' Lens opacities occur in one of 250 (0.4%) births. : Opacities that occlude the visual axis and prevent the development of vision or induce amblyopia are uncommon. However, it is these children who require early diagnosis, early surgical treatment and rapid postoperative aphakic rehabilitation to achieve visual success.

DIAGNOSIS

Congenital, or more properly infantile, cataracts are present at birth or develop within the first few months of life.' Other cataracts may not be discovered until later childhood as progressive visual deficits direct attention to their presence. Cataracts may be associated with systemic or genetic disease syndromes; as sporadic cataracts, associated with ocular disease; trauma, or they can occur without an obvious etiology. Patients harboring multiple congenital systemic anomalies increase the suspicion of coexistent ocular defects. Eyes suffering ocular trauma from a wide variety of agents may have an acute onset of the cataract with visual loss or develop a slowly progressive insidious opacification of the lens over many years.

Early discovery of infantile cataracts is dependent upon the education of non-ophthalmic medical and paramedical personnel which includes obstetricians, pediatricians, family practitioners, nurses, parents and teachers.

The presence of bilateral cataracts is suspected in an infant with poor visual fixation reflexes or acuity at a time when normal visual responses are developing. The onset of nystagmus, at two to three months of age, indicates bilateral visual deprivation. Satisfactory visual rehabilitation is often impossible in these children. Children with unilateral cataracts have no visual abnormalities if the fellow eye is normal. The parents may test the child and note a visual, behavioral or emotional change occurring when the normal seeing eye is covered.

The first ocular sign of cataract is that of leukokoriaor a white or gray reflex in the pupil under certain lighting conditions. Microphthalmos, particularly in unilateral cataract eyes, is also a frequent finding. The inability to obtain a red reflex or observe retinal details with the ophthalmoscope should alert an examining physician to the possibility of a lens opacity. Strabismus is frequently a presenting sign in unilateral cataract patients or in bilateral cataract patients where it indicates the onset of amblyopia in the eye with the more opaque lens opacity.

An ocular examination, including fundoscopy, should be performed on all babies before they are discharged from the newborn nursery. However, adequate pupillary dilatation is often difficult to achieve in infants because of the poor development of the iris dilator muscle. The instillation of one drop of 0.5% or 1% cyclopentolateand 2 1/2% phenylephrine dilates the pupils wide enough for a view of the lens and retina.

When the diagnosis of cataract is suspected, ophthalmologic examination through widely dilated pupils confirms the presence, the morphologic type and the effect on visual function by the cataract ( Figure I). Visual acuity measurements with Snellen letters, numbers and the illiterate Es may be obtained in cooperative and responsive children four years of age and older. The Sheriden-Gardiner test consists of the identification of isolated optotypes and is useful in children of three years of age and older.4

In younger uncooperative or mentally retarded patients an evaluation of the visual fixation reflexes is necessary. Preferential looking techniques, optokinetic nystagmus and fixation responses on cover testing are incorporated. Pattern reversal visual evoked responses (VER) may indicate differences in visual quality between the two eyes as well as the presence or absence of intact visual neural pathways. It has been determined by the VER method that an infant's visual acuity at six months of age is 20/20 by the attainment of wave forms…

Infantile cataracts are the most significant cause of remediable blindness in children.' Lens opacities occur in one of 250 (0.4%) births. : Opacities that occlude the visual axis and prevent the development of vision or induce amblyopia are uncommon. However, it is these children who require early diagnosis, early surgical treatment and rapid postoperative aphakic rehabilitation to achieve visual success.

DIAGNOSIS

Congenital, or more properly infantile, cataracts are present at birth or develop within the first few months of life.' Other cataracts may not be discovered until later childhood as progressive visual deficits direct attention to their presence. Cataracts may be associated with systemic or genetic disease syndromes; as sporadic cataracts, associated with ocular disease; trauma, or they can occur without an obvious etiology. Patients harboring multiple congenital systemic anomalies increase the suspicion of coexistent ocular defects. Eyes suffering ocular trauma from a wide variety of agents may have an acute onset of the cataract with visual loss or develop a slowly progressive insidious opacification of the lens over many years.

Early discovery of infantile cataracts is dependent upon the education of non-ophthalmic medical and paramedical personnel which includes obstetricians, pediatricians, family practitioners, nurses, parents and teachers.

The presence of bilateral cataracts is suspected in an infant with poor visual fixation reflexes or acuity at a time when normal visual responses are developing. The onset of nystagmus, at two to three months of age, indicates bilateral visual deprivation. Satisfactory visual rehabilitation is often impossible in these children. Children with unilateral cataracts have no visual abnormalities if the fellow eye is normal. The parents may test the child and note a visual, behavioral or emotional change occurring when the normal seeing eye is covered.

The first ocular sign of cataract is that of leukokoriaor a white or gray reflex in the pupil under certain lighting conditions. Microphthalmos, particularly in unilateral cataract eyes, is also a frequent finding. The inability to obtain a red reflex or observe retinal details with the ophthalmoscope should alert an examining physician to the possibility of a lens opacity. Strabismus is frequently a presenting sign in unilateral cataract patients or in bilateral cataract patients where it indicates the onset of amblyopia in the eye with the more opaque lens opacity.

An ocular examination, including fundoscopy, should be performed on all babies before they are discharged from the newborn nursery. However, adequate pupillary dilatation is often difficult to achieve in infants because of the poor development of the iris dilator muscle. The instillation of one drop of 0.5% or 1% cyclopentolateand 2 1/2% phenylephrine dilates the pupils wide enough for a view of the lens and retina.

When the diagnosis of cataract is suspected, ophthalmologic examination through widely dilated pupils confirms the presence, the morphologic type and the effect on visual function by the cataract ( Figure I). Visual acuity measurements with Snellen letters, numbers and the illiterate Es may be obtained in cooperative and responsive children four years of age and older. The Sheriden-Gardiner test consists of the identification of isolated optotypes and is useful in children of three years of age and older.4

In younger uncooperative or mentally retarded patients an evaluation of the visual fixation reflexes is necessary. Preferential looking techniques, optokinetic nystagmus and fixation responses on cover testing are incorporated. Pattern reversal visual evoked responses (VER) may indicate differences in visual quality between the two eyes as well as the presence or absence of intact visual neural pathways. It has been determined by the VER method that an infant's visual acuity at six months of age is 20/20 by the attainment of wave forms equal to those of adults/ Electroretinograms are helpful in determining the presence of a functioning retina in patients with dense cataracts.

The effect of bilateral cataracts on visual acuity is not related to the morphology of the cataract or to its size, but rather inversely to its central density." Dense central cataracts, 3 mm in diameter or larger, should be considered amblyopiogenic. Incomplete unilateral cataracts affect the visual acuity of the involved eye as if the cataract were complete. These cataracts induce strabismus, strabismic and deprivation amblyopia.

MEDICAL EVALUATION

Evaluation of children with infantile cataracts determines etiology and helps to establish a prognosis. This procedure consists of an ophthalmologic history and physical examination to discover the type of lens opacity. Many cataracts are characteristic of the underlying disease which helps to determine etiology. Ocular examinations of the parents and siblings may also be helpful. Historical facts ascertain the occurrence of trauma, other systemic disease in the family and exposure to toxic elements. Since children with cataracts have a high risk of associated systemic disease, pediatric, neurologic, psychologic, dermatologicandgeneticconsultations aid in diagnosing many of the rare entities. Laboratory, x-ray, cardiographie, audiologic, and psychologic tests are performed (Table I).4,7

CLASSIFICATION

Infantile cataracts are classified according to their position within the crystalline lens.* A complete, mature or total cataract is one in which no red fundus reflex is visible through a dilated pupil (Figure 2). Partial cataracts are anterior dot ( Figure 3), anterior subcapsular (Figure 4), plaques (Figure 5), posterior subcapsular opacities ( Figure 6), posterior lenticonus, and anterior or posterior cortical opacities (Figures 7, 8 and 9). Zonular cataracts may be nuclear, lamellar, suturai, or peripheral in position. Lamellar cataract is the most common type of infantile cataract and consists of a zone of opacification surrounding a clear nucleus which in turn is surrounded by a clear cortex (Figure 10). Membranous cataracts are thick, dense and fibiotic and may be congenital or result from the absorption of mature cataracts. Lens opacities which are small, located in the lens periphery or translucent do not interfere with normal visual development.

Figure 1. Bilateral mature cataract in newborn.

Figure 1. Bilateral mature cataract in newborn.

Figure 2. Mature or total cataract with no fundus details visualized.

Figure 2. Mature or total cataract with no fundus details visualized.

Figure 3. Anterior polar dot lens opacity.

Figure 3. Anterior polar dot lens opacity.

Table

TABLE 1EVALUATION OF INFANTILE CATARACT PATIENTS

TABLE 1

EVALUATION OF INFANTILE CATARACT PATIENTS

Table

TABLE 1EVALUATION OF INFANTILE CATARACT PATIENTS

TABLE 1

EVALUATION OF INFANTILE CATARACT PATIENTS

Figure 4. Central small dense anterior subcapsular cataract.

Figure 4. Central small dense anterior subcapsular cataract.

Figure 5. Dense anterior capsule plaque often associated with trauma, Down's syndrome, atopic dermatitis, infantile tetany and chronic intraocular inflammations.

Figure 5. Dense anterior capsule plaque often associated with trauma, Down's syndrome, atopic dermatitis, infantile tetany and chronic intraocular inflammations.

Figure 6. Posterior subcapsular cataract.

Figure 6. Posterior subcapsular cataract.

Many infantile cataracts are associated with microphthalmia of either one or both eyes (Figures 11 and 12). Persistent hyperplastic primary vitreous induces cataract formation in a microphthalmic eye by the invasion of the lens by a fibrovascular membranous remnant of the primitive hyaloid system which did not involute properly (Figure 13).

Transient cataracts occur in premature infants, in patients with galactosemia of both the transferase and kinase deficiencies, in diabetes mellitus, steroid-induced opacities, sporadic infantile cataracts, and cataracts associated with premature infants."

Acquired cataracts are those which are secondary to an insult to the lens such as occurs with trauma (Figures 14 and 15), intraocular inflammations (Figure 16), toxicities, or ocular manifestations of systemic diseases.8 Frequently there is no distinct separation of infantile and acquired forms. Cataracts which occur in early childhood produce the same anatomical configuration and visual physiological complications regardless of etiology.

Cataracts may be unilateral or bilateral. If they are bilateral they may be asymmetrical in development.

Unilateral cataracts discovered in the neonatal period are frequently large, dense and central (Figure 17).

ETIOLOGY

Cataracts may be associated with ocular, systemic, chromosomal, genetic or generalized syndromes. Sporadic cataracts are the most common and constitute onethird of infantile cataracts."'* Many of these may represent new mutations, however. An additional 8% to 25% of cataracts are familial and these may be associated with familial syndromes rather than as an isolated familial cataract.

Figure 7. Cortical cataract viewed by retro-illumination as light is returned from the retina.

Figure 7. Cortical cataract viewed by retro-illumination as light is returned from the retina.

Autosomal dominant hereditary is the most frequent mode of transmission and is regular with complete penetrance and similar expressivity. Autosomal recessive cataracts are associated with consangueous unions. Xlinked recessive cataract is rare and is associated with microcornea." Genetic syndromes, mode of inheritance, age of onset, lens location and laterality are summarized in Table 2.

Cataracts may be associated with a multitude of systemic constellations including craniofacial stenosis, mandibulofacial, skeletal, apical, central nervous system, muscular, dermatologie, renal and chromosomal syndromes. Embryopathies or nongenetic diseases affecting the fetus produce cataracts and consist of the rubella syndrome and other viral, bacterial and protozoal intrauterine infections. Deficiencies of calcium, glucose or oxygen and metabolic disturbances producing galactosemia, diabetes mellitus, homocystinuria, Wilson's, Fabry's and Refsum's disease, and mannosidosis also induce lens opacity. Infants and children have cataracts related to ocular diseases or anomalies which include: retrolental fibroplasia, infantile glaucoma, retinoblastoma, microphthalmos, anterior chamber cleavage syndromes, colobomas, aniridia, ectopia lentis, persistent hyperplastic primary vitreous, retinal dysplasia, retinitis pigmentosia and retinal detachment. Direct ocular trauma, ionizing radiation and the effects of maternal or infant drug therapy are also considered when investigating the etiology of infantile cataracts.

SURGICAL INDICATIONS AND PROGNOSIS

The indications for surgery of infantile cataracts have been profoundly altered since the publication of the works of Wiesel and HubeJ9-'2 and von Noorden and associates11'14 on the effect of deprivation amblyopia visual development in animals. Their neurophysiologic research has indicated that a sensitive period exists for the reversal of deprivation amblyopia in kittens and monkeys. Extrapolation of this concept to the human has been made by ophthalmic surgeons, but the sensitive period's duration remains unknown. It has been suggested that this period is up to two months of age.15' 6 There is an increased sensitivity from six to 18 months of age followed by gradually declining sensitivity for several years. After age eight to ten years, visual acuity is not lost when there is gradually decreasing vision.

Figure 8. Same cortical cataract viewed by direct illumination.

Figure 8. Same cortical cataract viewed by direct illumination.

Figure 9. Cortical dot opacities randomly distributed throughout lens cortex.

Figure 9. Cortical dot opacities randomly distributed throughout lens cortex.

Figure 10. Nuclear cataract.

Figure 10. Nuclear cataract.

Figure 11. Microphthalmic right eye in patient with persistent hyperplastic primary vitreous (PHPV). Normal left eye.

Figure 11. Microphthalmic right eye in patient with persistent hyperplastic primary vitreous (PHPV). Normal left eye.

Figure 12. Microphthalmic eye with microcornea, inferior iris coloboma and nuclear cataract.

Figure 12. Microphthalmic eye with microcornea, inferior iris coloboma and nuclear cataract.

Figure 13. PHPV fibrovascular membrane posterior to clear crystalline spherophakic lens. Long ciliary processes are noted interiorly.

Figure 13. PHPV fibrovascular membrane posterior to clear crystalline spherophakic lens. Long ciliary processes are noted interiorly.

Patients with bilateral complete cataracts are diagnosed early in life because of the presence of leukokoria or a lack of visual attention and the onset of nystagmus or strabismus.1'' Patients with bilateral incomplete congenital cataract may exhibit abnormal behavior recall with little or no interest in visual tasks. Slow progression of the lens opacification permits visual development to proceed at almost normal levels in some children until vision decreases and surgery becomes necessary at later ages of childhood. The visual prognosis in children with bilateral partial cataracts is often better than for children with complete cataracts discovered in the neonatal period. These later patients frequently have irreversible deprivation amblyopia even if they have had early cataract surgery and visual rehabilitation. Bilateral cataracts are more often related to hereditary causes and generalized embryopathies.

Early discovery of a unilateral infantile cataract is dependent upon the education of non-ophthalmic medical and paramedical personnel. Patients with large, dense, unilateral infantile cataracts discovered in the neonatal period often suffer more severe deprivation amblyopia and achieve poorer visual results than patients with small lens opacities for these latter cataracts undergo prolonged periods of normal visual development.17 In addition, children with early onset infantile cataracts frequently have more severe associated systemic and ocular defects both in the anterior and posterior segment of the eye, or as microphthalmia. Strabismus is a frequent complication and contributes to amblyopia and visual loss.

Figure 14. Corneal laceration repaired with interrupted sutures. Central cortical and nuclear cataract.

Figure 14. Corneal laceration repaired with interrupted sutures. Central cortical and nuclear cataract.

Figure 15. Traumatic dislocated cataractous lens.

Figure 15. Traumatic dislocated cataractous lens.

Figure 16. Nuclear and cortical cataract following uveitis associated with rheumatoid arthritis. Posterior synechiae fix iris to lens at pupil for 360°.

Figure 16. Nuclear and cortical cataract following uveitis associated with rheumatoid arthritis. Posterior synechiae fix iris to lens at pupil for 360°.

Dense unilateral partial congenital cataracts are often detected later in childhood, particularly at preschool examinations. The onset of strabismus or poor fixation habits should also alert the parents or physician to the presence of decreased vision. The prognosis for visual rehabilitation is not as good in these patients because of late detection. Other children do achieve good visual success if they have had the opportunity to develop form visual acuity prior to the increasing opacification of their lens.

The significance of these findings to the primary care physician as well as the ophthalmologist is to establish the very early diagnosis of infantile cataract and institute early surgical therapy, optical correction and amblyopia occlusion therapy during the human infant's sensitive period. The motivation of the parents is a very important consideration to the success of the regimen.

Many patients have cataracts which are compatible with good vision.6 Frequent re-evaluations of the fixation reflexes and visual acuity is required. Refraction, with the prescription of appropriate glasses and bifocals may help to prevent visual loss. Occlusion of the fellow eye may be necessary to prevent amblyopia in the eye with the more dense cataract.

Some children manifest poor visual acuity at distance and a telescope may be useful even though the visual field is markedly restricted. Other children are able to read adequately and satisfy their school needs with magnification or by holding printed material very close to their better eye. Surgery is deferred until school tasks become difficult and hinder educational progress.

Table

TABLE 2CATARACTS ASSOCIATED WITH GENETIC SYNDROMES

TABLE 2

CATARACTS ASSOCIATED WITH GENETIC SYNDROMES

Table

TABLE 2CATARACTS ASSOCIATED WITH AFNFTIC SYNDROMES

TABLE 2

CATARACTS ASSOCIATED WITH AFNFTIC SYNDROMES

Atropine pupillary dilation is useful to enhance vision in patients with axial opacities. However, these patients also require tinted glasses with bifocals to allow vision at both distance and near and to reduce the glare associated with dilated pupils. Optical iridectomies have been performed in the past to allow for the development of enhanced vision in patients with immature central cataracts. However, the success of the procedure was minimal and its use has been discontinued.15

INDICATIONS FOR SURGERY

Unilateral Infantile Cataract

The indications for surgery in patients with unilateral complete congenital cataract remain highly controversial. Some patients may have their visual acuity improved by early surgery, but in the majority vision remains unsatisfactory.18,19 This may be the result of associated anatomical ocular defects or the presence of strabismus, but most important is the occurrence of deprivation amblyopia due to occlusion of the visual axis during the sensitive period. If the axial lens opacity is greater than 3 mm in diameter, the visual axis is occluded, or a poor fundus reflex is observed, surgery is indicated at the time of discovery of the cataract.

Figure 17. Mature cataract in microspherophakic lens in rubella syndrome.

Figure 17. Mature cataract in microspherophakic lens in rubella syndrome.

Unilateral cataracts discovered in the neonatal period are frequently large, dense and central and surgery is indicated within the first week of life, or as soon after the discovery of the cataract as possible.20,21

Figure 18. Large central traumatic corneal vascularized scar. Posterior subcapsular cataract.

Figure 18. Large central traumatic corneal vascularized scar. Posterior subcapsular cataract.

Bilateral Infantile Cataracts

Patients born with dense axial or complete bilateral infantile cataracts require surgery in the more involved eye within the first week of life.22 The second eye is operated two to three weeks later depending upon the amount of residual inflammation existing in the first eye. Pratt-Johnson has suggested doing the second eye within five days of the first to increase the possibility of obtaining good vision in each eye."' This schedule does not allow time to observe the postoperative reaction of the first eye to surgery. The longer observation period still permits surgery of the second eye within the sensitive period, but after the possible onset of uveitis, endophthalmitis and pupillary block or angle closure glaucoma.

Patients with early onset bilateral complete or axial cataracts often develop nystagmus at two to three months of age, either on a familial or visual deprivation basis. Cataract surgery and optical rehabilitation is indicated prior to the onset of nystagmus to establish secure central fixation reflexes. If this crucial time is lost, nystagmus will persist throughout life with its coincident reduction in visual acuity.

Patients with bilateral cataracts may have an asymmetrical onset of their cataracts. The more severely involved eye may develop amblyopia which is further complicated by aphakia. Early optical correction and the occlusion of the sound eye helps to prevent this complication. If strabismus develops, strabismus surgery is indicated as soon as the central fixation reflex is developed in each eye and the strabismic angle remains stable.23

In older children surgery is indicated when the corrected visual acuity falls below 20/70 with full pupillary dilation and maximal optical correction in place.

Figure 19. Dense mature or total cataract in patient with aniridia. Phacoemulsifier tip is removing the lens material by irrigationaspiration. The ultrasonically driven needle fragments the lens by rapid oscillation.

Figure 19. Dense mature or total cataract in patient with aniridia. Phacoemulsifier tip is removing the lens material by irrigationaspiration. The ultrasonically driven needle fragments the lens by rapid oscillation.

Traumatic and Acquired Cataracts

The onset of traumatic cataracts may be acute or delayed.24 Acute cataracts are associated with severe contusion or perforating injuries to the globe. If the lens capsule is ruptured and lens material is identified in the anterior chamber or is observed protruding through the wound, cataract surgery is indicated at the time of the penetrating wound repair. The perforating wound is closed first and a controlled cataract aspiration through a small limbal incision removes the remainder of the lens capsule, cortex and nucleus as well as vitreous, hemorrhage, fibrin and other debris. If the posterior capsule is traumatically ruptured at the time of primary cataract extraction, the capsule and the anterior vitreous may be removed with mechanical suction cutting devices.

Delayed cataracts follow contusion and perforating injury or are secondary to other ocular insults such as toxicities by drugs, metabolic imbalances, ionizing radiation or intraocular inflammations. These cataracts are slow to develop and surgery is performed when the visual acuity reaches 20/70 to 20/ 100 or less or when the visual fixation reflex is poorly maintained. The intraocular pressure following traumatic cataract also should be within normal range being neither glaucomatous or hypotonic (Figure 18).

Infants and children in the amblyopiogenic age period from birth to six years who suffer ocular trauma require surgery when the visual axis becomes occluded, strabismus arises and there is a decrease in the quality of the fixation reflex or measured visual acuity with optical correction in place. These children respond to therapy in the same manner as patients with unilateral infantile cataracts. The visual results depend upon the age of the patient at the time of the occlusion of the visual axis by the cataract, the rapidity of postoperative optical correction and the severity of the trauma to other ocular structures.

Surgery on acquired lens opacities following chronic intraocular inflammations is indicated when the visual acuity falls below 20/70 to 20/ 100 or the fixation reflexes are poor. Surgery is performed at any period in the inflammatory cycle, however, minimal anterior chamber flare and cells is preferred. This situation is rarely obtained. Preoperative corticosteroid coverage is essential for the successful suppression of inflammation.

Diabetic cataracts may occur at any age but they arise most commonly in juvenile diabetics between the ages of seven and 16 years. The typical bilateral multiple subcapsular opacities may progress to maturity very rapidly. A reversal of the cataract may occur with adequate control of the diabetes if the lens protein has not undergone denaturation. The cataracts are removed without operative complications.

SURGERY OF INFANTILE CATARACTS

The child's eye differs from the adult's eye in several important parameters."5 There is increased pliancy with less rigidity of the scleral sac. When the eyes are open, there is more pressure from scleral collapse upon the intraocular contents which predisposes to vitreous loss. This factor is exaggerated by the variations in the intraocular pressure that may occur during general anesthesia. Another difference in the child's eye is the continued attachment by the ligamentum-hyaloideocapsulare to the anterior vitreous face and the posterior lens capsule. This attachment makes intracapsular cataract extraction hazardous for it leads to capsular rupture, vitreous leakage into the anterior chamber and late retinal detachment.

SURGICAL TECHNIQUES

The small limbal incision aspiration-irrigation technique advocated by Scheie in 1960"ft and its many modifications has increased the safety and advisability of performing successful surgery in infants as young as the first week of life.25 The availability of improved surgical microscopes, microsurgical instruments and techniques, sutures, and needles as well as anesthesia has reduced the surgical risks. The trend toward providing specialized pediatric medical care centers contributes to the safety and comprehensive management of the cataracts and the frequently co-existing medical problems that these children harbor.

Two general philosophies of cataract aspiration are in vogue: anterior capsulotomy/capsulectomy aspirationirrigation techniques with an intact posterior capsule remaining at the conclusion of the operation25 or cataract aspiration-irrigation and posterior capsulectomy combined with an anterior vitrectomy either through a limbal or pars plana incision.7,27-29

Limbal Incisions

An incision is made through the surgical limbus into the anterior chamber. A wide anterior capsulectomy is performed to reduce the occurrence of dense secondary membranes.25 Aspiration-irrigation of the cataract is accompanied utilizing a syringe and 20 gauge needle or with mechanical devices such as the phacoemulsifier (Figure 19), or by cutting aspiration instruments: Vitreous Infusion Suction Cutter( VISC), Rotoextractor, Suction Infusion Tissue Extractor (SITE), Automated Vitrotome, Ocutome, Vitrophage and the Grieshaber Vitreous Cutter are some of these instruments.27 With each technique, the lens cortex and nucleus are aspirated in a one-stage operation. The wound is closed and the operation is concluded with the instillation of air to reconstitute the anterior chamber depth.

The variation to the above technique is the aspiration of the lens material through a limbal incision and at the conclusion of the operation, the aspiration cutting instrument removes a large central section of the posterior capsule as well as the anterior vitreous body.7'27-29 This procedure limits the complication of an opaque secondary membrane as well as the hazards of a second anesthesia.

Controversy exists as to whether the posterior capsule and anterior vitreous should be removed at the time of lens extraction.7 Hoyt and Nichol'" have recently shown that the lensectomy, anterior vitrectomy procedure induces cystoid macular edema in infants with its accompanying visual loss and have suggested the abandonment of this procedure. This author still feels that the posterior capsule should remain and the anterior vitreous should not be disturbed unnecessarily.

A primary capsulotomy may be performed by the introduction of a discission knife into the anterior chamber at the conclusion of the cataract aspiration and after the eye lens has been closed and, under direct visualization, the posterior capsule is opened. An additional method replaces the air with Healon and the capsule is opened with a discission knife without the disturbance of the anterior vitreous face.

Almost all pediatric patients develop, over a period of time, an opaque secondary membrane which requires a capsulotomy. Secondary discissions performed two to four weeks following the cataract aspiration is the safer choice (Figure 20). The posterior lens capsule becomes taut or rigid during the first few weeks following cataract aspiration and it separates from the underlying anterior vitreous face. This presents the surgeon with the opportunity to perform a discission through a tight membranous posterior capsule without disturbing the anterior vitreous face or introducing vitreous into the anterior chamber. Capsulotomies are performed by passing a very sharp 2 to 2 I /2 mm Haab discission knife through a limbal incision and into the pupillary space. An opening in the posterior capsule is created. A contact lens is refitted at this time and other ocular examinations including tonotomy and fundoscopy are performed.

Figure 20. A secondary membrane or opacified posterior capsule is being opened (Discission) with a short-bladed discission knife.

Figure 20. A secondary membrane or opacified posterior capsule is being opened (Discission) with a short-bladed discission knife.

Pars Plana Incision

With the advent of automated vitrectomy instruments, a pars plana approach becomes feasible. An incision is made posterior to the limbus through the pars plana of the ciliary body. The instrument is passed into the pupillary space and, under direct observation, the posterior capsule, lens cortex, nucleus, and anterior capsule as well as an anterior and central vitreous to the depth of the optic disc is removed.28

SURGICAL COMPLICATIONS

The commonest operative complication of infantile cataract surgery is posterior capsular rupture and vitreous loss.25'" Mechanical vitreous suction cutting devices remove all unwanted vitreous from the wound, the iris and anterior chamber.

POSTOPERATIVE COMPLICATION

The major postoperative complications following cataract surgery in children are: secondary membrane formation, corneal opacification, glaucoma, retinal detachment, and cystoid macular edema.

There is an increased frequency of postoperative occluded and secluded pupils and opaque postpseudophakos membranes following extracapsular cataract extractions. The incidence of these membranes is much higher following pediatric cataract surgery.25

The membrane arises from anterior capsular epithelial cell proliferation to undergo pseudometaplastic change and form the membranes.32 Biopsy specimens of the membranes were studied by light and electron microscopy obtained from two patients. Histopathologically, these membranes demonstrated fibrous tissue containing lens capsule and nests of enlarged swollen and vacuolated lens epithelial cells with elongated spindle-shaped epithelial cells, each surrounded by a PAS positive basement membrane.

Similar membranes may occur in the presence of chronic intraocular inflammations, or postoperatively in some infants' eyes following cataract aspiration procedures. Occlusion of the visual axis by the membranes is of greater consequence in children than in adults because of a child's visual immaturity and ability to develop amblyopia. Wider anterior capsulotomies with greater removal of the capsular epithelium may reduce the source of proliferation of fibrous tissue which induces opaque posterior capsules, occluded and secluded pupils.

Early transient striate keratitis and corneal edema rarely occur in children following cataract aspiration. Scleral collapse, anterior chamber collapse, and trauma to the corneal endothelium by lens elements circulating within the anterior chamber during surgery produce this complication. Striate keratitis clears within the first two or three postoperative days.

The preservation of the corneal endothelial cells remains of great importance during intraocular surgery.'1 The integrity of the corneal endothelium is an essential factor for the maintenance of the transparency of the cornea. Endothelial cells comprise a single layer of nonreplicating cells which diminish progressively throughout life. The corneal endothelium has a healing reserve or potential to compensate forcell loss following injury. The remaining cellsenlarge, become pleomorphic and serve to cover the traumatized corneal endothelium surface. When the population of the corneal endothelial cells is reduced to a critical level, corneal swelling and cloudiness begins, resulting in visual loss.

Aphakic glaucoma is related to the surgical procedure or occurs as late open angle glaucoma.'4 Post-cataract surgery glaucoma is related to posterior synechiae with secondary angle closure glaucoma, inadequate irridectomies with secondary angle closure, persistent postoperative inflammation, and steroid induced trabecular meshwork malfunction.

The chronic open angle form of glaucoma develops slowly and may not become apparent for years or decades after the operation for congenital cataract. It is important to periodically measure intraocular pressures and examine the optic disc of all patients who have had infantile cataract surgery. Since the postoperative level of vision may not be normal, the patient frequently does not recognize the slow diminution of vision until irreversible atrophic optic nerve changes have occurred.

Retinal detachment following infantile cataract surgery has been noted in the literature to be related to the old needling operation. The incidence of retinal detachment following aspiration-irrigation techniques remains low. However, the true incidence is undetermined since a follow-up period of 20 to 30 years or more is required. Some surgeons feel that the surgical correction of the retinal detachment is more difficult to accomplish, while other groups feel that there is no difference in the surgical success rate for re-attachment of the aphakic pediatric retina when compared to the adult aphake.

Aphakic cystoid macular edema (CME) has been reviewed in two series with fluorescein angiography (Figure 2l).'U)'"v' One series following aspiration-irrigation showed no CME when studied from five weeks to four years after surgery even if the vitreous face had been disturbed.16 A second study indicates eyes undergoing lensectomy-vitrectomy procedures developed cystoid macular edema in a high percentage of patients. Many eyes developed chronic edema and some contributed to visual loss. Only one eye with an aspiration procedure developed CME.36

APHAKIC REHABILITATION

Glasses

For patients in whom contact lens compliance appears to be reduced, there is reluctance by the parents to participate in their use, or for other social or economic factors, aphakic spectacles with an appropriate bifocal correction are prescribed (Figure 22).

To reduce the weight of spectacles with very high aphakic refractive errors, a 20 diopter Fresnel power prism is applied to a carrier spectacle lens in which the residual sphere, cylinder and bifocal is incorporated. Plastic aspherical lenses are often prescribed, but these lenses do not absorb ultraviolet and infrared rays as well as glasses. They are also thicker and scratch more readily. Absorptive or sunwear lenses are useful for patients with aphakia, particularly those undergoing chronic mydriasis. Low vision aids, either as telescopes for distance or magnifiers for near work may be incorporated into especially designed aphakic spectacles.

Contact Lenses

Contact lenses are the preferred aphakic correction for most infants and children. ,7 Keratometry and refraction, when possible, were performed upon small children under the same general anesthesia as the cataract aspiration. A contact lens is placed upon the eye within the first few postoperative days or when the inflammatory response of the eye subsides. The power of the contact lens has been increased from two to five diopters to compensate for the child's near visual world. The author suggests that the contact lens power be based upon an accurate distance refraction. The application of an overspectacle for the residual sphere and cylinder plus the introduction of an appropriate near bifocal addition completes the optimum optical correction. This concept widens the functional range of the rapidly developing infant's visual system and is most useful for children six months to a year of age and older. Other authors have suggested a lens for infinity or distance acuity on one eye, and a lens for near vision in the fellow eye of bilateral aphakes.38

Figure 21. Flourescein angiogram demonstrating cystoid macular edema.

Figure 21. Flourescein angiogram demonstrating cystoid macular edema.

Figure 22. Bilateral aphakia corrected with glasses. Bifocals are needed for near vision.

Figure 22. Bilateral aphakia corrected with glasses. Bifocals are needed for near vision.

The contact lens may be composed of any of the available substances and be either hard or soft providing that the fit is adequate, the lenses are easily applied to the eyes by the parent or patient and the lens is readily commercially available to compensate for high contact lens loss rates (Figure 23). A wide variety of lens powers and sizes must be available to the contact lens technician at the time of the Fitting. The smaller hard lenses are often superior for use in infants due to their ease of insertion and removal between smaller palpebral fissures. The large soft lens are more comfortable to wear and have a lower loss rate, but they frequently break or crease with repeated bending during insertion and removal.

Figure 23. Aphakic unilateral soft contact lens. Lenticule covers pupil, carrier extends onto sclera.

Figure 23. Aphakic unilateral soft contact lens. Lenticule covers pupil, carrier extends onto sclera.

Extended-wear, soft contact lenses offer an additional parameter (Figure 24). The lens may be applied to the eye and left in place for two weeks to a month without removal. Some ophthalmologists have suggested that the patients be examined at monthly intervals and rerefracted.21 Modifications of the lenses are made at this point to accurately compensate for changes in the refractive error as the child grows. This form is the most ideal contact lens, but not all children are able to wear them successfully and comfortably.

Inaccurate optics, as well as deprivation amblyopia, decreases the success of visual rehabilitation. Repeated refractions and modification of the contact lens and spectacles are made over the first two to three years of life to compensate for the rapid decrease in the refractive error of the infant aphakic eye.

INTRAOCULAR LENS

Patients six months to one year of age and up to nine years of age, who either fail to wear a contact lens following very early surgery or those being considered for cataract surgery, whom the parent and the ophthalmologist conclude will not wear a contact lens successfully, are candidates for intraocular lens implantation (Figure 25)."

Figure 24. Bilateral aphakic contact lenses.

Figure 24. Bilateral aphakic contact lenses.

The intraocular lens powers are the same as for an adult eye so that the child's eye grows toward this lens power. During growth and development, optical compensation is provided by the prescription of spectacles for the residual distance sphere or cylinder plus a bifocal correction for near. There is a reduction in anisometropia and aniseikonia with an intraocular lens which helps to reduce deprivation amblyopia. There is also a constant application of the aphakic optics as well as an absence of stress to the patient and the parent surrounding the insertion and removal of contact lenses.

Over the past eight years the following indications and contraindications have been advocated for intraocular lens implantation in children. The procedure remains confined to monocular aphakic children because of the unknown very long-term effects of the presence of an intraocular lens in the human eye.

Intraocular lens implantation is indicated for children with familial or sporadic infantile cataracts, anterior persistent hyperplastic primary vitreous, posterior lenticonus, and patients up to the age of nine years with progressive late onset juvenile cataracts. Aphakic patients who fail to wear contact lenses at any time after one year of age become candidates for secondary intraocular lens implantation.

Patients with traumatic cataracts one to six years of age may receive an intraocular lens either as a primary or secondary procedure following contact lens failure. If the eye is not severely damaged by corneal scars, glaucoma or posterior polar defects, visual restoration is possible providing the visual axis has not been occluded for long periods of time by the presence of the cataract. Antiamblyopia therapy, and over-spectacle correction for residual distance and near optical defects aids in the restoration of visual function.

Figure 25. Two-loop iris plane intraocular lens sutured to iris superiorally with 9-0 prolene suture.

Figure 25. Two-loop iris plane intraocular lens sutured to iris superiorally with 9-0 prolene suture.

Older patients with traumatic and acquired cataracts, with and without corneal scars, may receive an intraocular lens either as a primary procedure or following contact lens failure. The visual prognosis is excellent and the intraocular lens is well tolerated within the eye for prolonged periods of time.40

Contraindications to intraocular lens implantation include microphthalmic eyes with corneas less than IO mm in diameter. Sufficient space is not present within the anterior chamber to assure that corneal endothelial touch will not occur. Patients with large central corneal scars which occlude the visual axis continue to have poor postoperative visual results for corneal grafting. Eyes with aniridia, either congenital or acquired following trauma, do not offer a sufficient support system for an intraocular lens utilizing either an anterior chamber or iris suture lens. If the capsular bag is present at cataract surgery, secure lens loop capsular fixation may occur wit h the implantation of a posterior chamber lens but the longterm support of these lenses in children is unknown. Slow posterior and/ or inferior migration of the intraocular lens may occur which induces increasing refractive errors and amblyopia.

Eyes with either traumatic or syndrome-related dislocated lenses are not selected for intraocular lens implantation due to the high incidence of retinal detachment and secondary glaucoma. Eyes with infantile or congenital glaucoma are also not implantation candidates, for these eyes have been shown to redevelop glaucoma which is extremely difficult , if not impossible, to control either medically or surgically. No eyes are implanted with chronic intraocular inflammation including the rubella syndrome, juvenile rheumatoid arthritis, toxocara, toxoplasmosis or par planitis. Late exacerbations of these inflammations occur which may be accompanied by secondary glaucoma. If an eye is known to have had a pre-existing retinal detachment, macular lesion or optic nerve defect or atrophy, intraocular lens implantation is not warranted.

Figure 26. Aphakic left eye with contact lens. Light tight skin occlusion of the right or normal eye is undertaken to reverse amblyopia.

Figure 26. Aphakic left eye with contact lens. Light tight skin occlusion of the right or normal eye is undertaken to reverse amblyopia.

If a very careful selection of implantation candidates among children and adolescents is observed, these lenses are well tolerated and function visually as well as their adult counterparts following senile cataract extractions.

EPIKERATOPHAKIA

Kaufman and colleagues have introduced the concept of epikeratophakia. This technique consists of the application of a corneal graft which has been prelathed to the proper aphakic power. It is composed of either freshfrozen or preserved human tissue. The graft is sutured into a peripheral corneal groove in the recipient's epithelium denuded cornea. The graft may be changed as the refractive error modifies with age.

The disadvantages of this technique are that it requires: human tissue for optical correction, a complicated lathing procedure to produce the proper aphakic powers, a surgical procedure to modify the graft, and prolonged graft clearing time following surgery. The stability of the graft appears to be excellent. An overcorrection for residual sphere and cylinder plus bifocals is still necessary.

AMBLYOPIA

One of the most important aspects of aphakic visual rehabilitation in unilateral aphakic patients is the application of light-tight occlusion over the sound eye up to 90% of the child's waking hours (Figure 26). Parents must be diligent in their observation and application of the patch in order for any successful rehabilitative efforts to occur.

STRABISMUS

Strabismus is a frequent complication of aphakia. When strabismus develops, early surgery is indicated to restore a normal ocular alignment and secure the best possible peripheral fusion response. Occlusion is undertaken over the sound eye until the strabismic eye develops central fixation. When the angle is stable, surgery is performed.

VISUAL RESULTS

Visual acuity achieved by aphakic children is complicated by the presence of pre and postoperative ocular anatomical defects as well as sensory and motor anomalies peculiar to children.4' Systemic disease complications, particularly mental retardation, often make visual evaluation difficult. Visual evoked response, preferential-looking techniques and evaluation of the visual fixation reflexes remain as the only parameters for visual evaluation.44 Observation of the child's behavior toward visual tasks or educational assignments is helpful. The results following traumatic cataract surgery in children are superior to those following infantile cataract surgery. High degrees of visual acuity are precluded, however, by the magnitude of pre-existing injuries to the anterior segment, glaucoma and macular, retinal or optic nerve defects which reduce vision.

Patients with unilateral complete congenital cataracts achieve the poorest visual result. Deprivation amblyopia, older ages at time of surgery, prolonged rehabilitation or failure of rehabilitation techniques and associated congenital abnormalities contribute to this poor result. Patients with unilateral partial cataracts achieved improved visual results, particularly in older child ren.43 This enhanced visual capability relates to the opportunity to develop vision in these eyes before the cataract became dense enough to occlude the visual axis.

Bilateral complete cataract patients also do not achieve high degrees of visual acuity if surgery is required at early ages. Visual deprivation amblyopia, nystagmus, microphthalmos and associated systemic defects, particularly mental retardation, occur in many patients and preclude the achievement of high visual acuities.

Patients with bilateral partial infantile cataracts achieve high levels of visual acuity particularly if the patient is operated on after the age of one year. These patients have less severe deprivation amblyopia and associated anomalies as well as a longer time for the development of normal visual reflexes prior to visual loss.

The key to success for these patients is to operate in the very early neonatal sensitive period and to apply vigorous optical rehabilitative methods to achieve the best possible acuity.

REFERENCES

1. Taylor D. Rice NSC: Congenital cataract, a cause of preventable child blindness. Arch Dis Child 1982; 57:165-167.

2. Merin S: Congenital cataract, in Goldberg M (ed): Genetic and Metabolic Eye Disease. Boston, Little Brown & Co, 1974, pp 337-356.

3. Hiles DA. Biglan AW: Indications for infantile cataract surgery. Im Ophthalmol Clin 1977; 1 7(4):39-46.

4. Kennerdcll JS: Preoperative evaluation of juvenile cataracts. Ini Ophthalmol Clin 1977: I7(4):3-I4.

5. Sokol S. Dobson V: Pattern reversal visually evoked potential in infants. Invest Ophthalmol 1976: 15:58-61.

6. Crawford JS: Conservative management of cataracts. Im Ophthalmol Clin 1977: l7(4):3l-35.

7. Price Rl.. Crawford JR. Yeh H. et al: Medical and surgical management of children with cataracts. Perspectives in Ophthalmology 1978; 2:49-54.

8. Hiles DA, Carter BT: Classification of cataracts in children. Im Ophthalmol Clin 1977; 17(4): 15-29.

9. Wiesel TN. Hubel DH: Effects of visual deprivation on morphology and physiology oí cells in the cats lateral geniculate body. J Neurophcxiol 1963: 26:978-993.

10. Wiesel TN. Hubel DH: Single-cell responses in striate cortex of kittens deprived of vision in one eye. J Neurophysiol 1963; 26:1003-1017.

11. Wiesel TN. Hubel DH: Comparison of the effects of unilateral and bilateral eye closure on cortical unit responses in kittens. J Neurophvsiol 1965; 28:1029-1040.

12. Wiesel TN. Hubel DH: Extent of recovery from the effects of visual deprivation in kittens. J Neurophysiol 1965: 28:1060-1072.

13. Von Noorden GK: Experimental amblyopia in monkeys. Further observation and clinical correlations. Invest Ophthalmol 1973; 12:721-726.

14. Baker FH, Grigg P, von Noorden GK: Effects of visual deprivation and strabismus on the responses of neurons in the visual cortex ofthe monkey, including studies on the striate and pre-striate cortex in the normal animal. Brain Res 1974; 66:185-20«.

15. Awaya S: Stimulus vision deprivation amblyopia in humans, in Rcineckc R D (ed): Strabismus. Proceedings of the Third Meeting ofthe International Strabismological Association. New York, Grune & Stratton lnc, 1978; ? 31 .

16. Vaegan TD: Critical period for deprivation amblyopia in children. Trans Ophthalmol Soc UK 1979; 99:432-439.

17. H elevest on EM. Saunders RA. Ellis FD: Unilateral cataracts in children. Ophthalmic Surg 1980: 11:102-108.

18. Weber SW, Crawford JS, Ardnt JH, et al: Visual acuity after iridectomy or aspiration for congenital cataract: Experimental and clinical studies. Can J Ophthalmol 1978; 13:229-236.

19. Ryan SJ. Maumanee AE: Unilateral congenital cataracts and their management. Ophthalmic Surg 1977; 8:35-39.

20. Pratt-Johnson JA. Tillson G: Visual results after removal of congenital cataracts before the age of one year. Can J Ophthalmol 1 98 1; 16:19-21.

21. Belle r R, Hoyt CS, Marg E, et al: Good visual function after neonatal surgery for congenital monocular cataracts. Am J Ophthalmol 1981:91:559565.

22. Rogers GL. Tishler CL. Tsou BH. et al: Visual acuities in infants with congenita] cataracts operated on prior to six months of age. Arch Ophthalmol 1981: 99:999-1003.

23. Shapiro A. Duval EJ: Visual functions following bilateral surgery of congenital cataracts in children. J Pediatr Ophthalmol Strabismus 1979: 16:176-179.

24. Hiles DA. Wallar PH. Biglan AW: Surgery of traumatic cataracts. Int Ophthalmol Clin 1977; 1 7(4): 147.

25. Hiles DA: Phacoemulsification of infantile cataracts. Int Ophthalmol Clin 1977; I7(4):83-I02.

26. Scheie HG: Aspiration of congenital or soft cataracts: A newtechnique. Am J Ophthalmol I960: 50:1048-1056.

27. Calhoun JH: Cutting-aspiration instruments. Int Ophthalmol Clin 1977: 17(4): 103-1 18.

28. Peyman GA. Rachand M. Goldberg M: Surgery of congenital and juvenile cataracts: A pars plicata approach with the vitrophage. Br J Ophthalmol 1978: 62:780-783.

29. Douvas NG: Phakectomy with shallow anterior vitrectomy in congenital and juvenile cataracts. De ? Ophthalmol 1981; 2:163-174.

30. Hoyt CS. Nickel B: Aphakic cystoid macular edema. Arch Ophthalmol 1982: 100:746-749.

31. Hiles DA. Choiiner B: Vitreous loss following infantile cataract surgery. J Pediatr Ophthalmol 1977; 14:193-199.

32. Hiles DA. Johnson BL: The role of the crystalline lens epithelium in postpseudophakos membrane formation. American Intra-Ocular Implant Society Journal 1980: 6:141.

33. Hiles DA, Biglan AW, Fetherolf EC: Central corneal endothelial cell counts in children. American Intra-Ocular Implant Society Journal 1979: 5:292300.

34. Phelps CD. Arafat NI: Open-angle glaucoma following surgery for congenital cataracts. Arch Ophthalmol 1977; 95:1985-1987.

35. Toyofuku M. Hirose T. Schepens CL: Retinal detachment following congenital cataract surgery. Arch Ophthalmol 1980; 98:669-675.

36. Poer DV. H eie vesto ? EM. Ellis FD: Aphakie cystoid macular edema in children. Arch Ophthalmol 1981; 99:249-252.

37. Hiles DA: Visual acuities of monocular IOL and non-?? L aphakic children. Ophthalmology 1980: 87:1296-1300.

38. Brent H, Lewis T, Maurer D: Hard contact lenses found successful for infants with aphakia. Ophthalmology Times 1982: 7(I0):4.

39. Hiles DA: Indications, techniques and complications associated with intraocular lens implantation in children, in Hiles DA (ed): Intraocular lens Implants In Children. New York. Crune & Stratton Inc. 1980. pp 189-268.

40. Reynolds .ID. Hiles DA. Johnson BL. et al: A histopathologic study of bilateral aphakia with a unilateral intraocular lens in a child. Am J Ophthalmol 1982; 93:289-293.

41. Morgan KS. Weber TP. Asbell PA, et al: The use of epikeratophakia grafts in pediatric monocular aphakia. J Pediatr Ophthalmol Strabismus 1981; 18:23-29.

42. Hiles DA. Waller PH: Visual results following infantile cataract surgery. Im Ophthalmol Clin 1977; 17:265-282.

43. Hiles DA: Visual acuities of monocular IOL and non-IOLaphakic children. Ophthalmology. 1980: 87:1296-1300.

44. Jacobson SG. Mohindra I. Held R: Development of visual acuity in infants with congenital cataracts. Br J Ophthalmol 1981; 65:725-735.

TABLE 1

EVALUATION OF INFANTILE CATARACT PATIENTS

TABLE 1

EVALUATION OF INFANTILE CATARACT PATIENTS

TABLE 2

CATARACTS ASSOCIATED WITH GENETIC SYNDROMES

TABLE 2

CATARACTS ASSOCIATED WITH AFNFTIC SYNDROMES

10.3928/0090-4481-19830801-03

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