Visual improvement after extraction of developmental cataracts is related to both extent of preoperative visual deprivation and effectiveness of postoperative visual rehabilitation.12 Better surgical and anesthetic techniques have enhanced visual outcome by allowing earlier cataract extraction and visual rehabilitation.12 With the advent of mechanical cutting/aspirating devices, the soft cataract found in children can be removed more safely.3"4 Many surgeons prefer an anterior approach through the limbus superiorly with ocutome removal of lens substance, capsule, and anterior vitreous.2
An alternative approach is via the pars plicata,4 which offers several advantages. These include easy access to all cortex including that at 12 o'clock, increased distance from the endothelium, less manipulation of the iris, and scleral closure. Rapid healing of the small scleral incision site allows early ambulation and contact lens fitting. This article reviews the outcome and incidence of surgical complications achieved with this approach.
METHODS AND PATIENTS
Records of cataract extractions performed from January 1981 through December 1987 were reviewed to identify patients who had undergone a pars plicata lensectomy/ vitrectomy and who had then been followed through December 1988 at The Hospital for Sick Children in Toronto. Criteria for inclusion in the study were as follows: diagnosis of developmental cataract(s) without additional ocular anomaly other than possible microphthalmos, uniform surgical approach, patient age at surgery less than 5 years, postoperative contact lens fitting, and outpatient follow up at The Hospital for Sick Children. All cases of cataracts related to trauma, inflammation, rubella, or persistent hyperplastic primary vitreous were excluded. The surgical procedure included the following steps: superior rectus bridle suture; bevelled inferotemporal peripheral corneal stab incision; infero-temporal corneal infusion line placement - 25-gauge needle attached to #25 polyethylene tubing and syringe for manual infusion of balanced salt solution with epinephrine 0.01% concentration; superotemporal conjunctival peritomy; measurement and mark of scleral incision site 1.5 mm to 3 mm from the anterior limbus (depending on size of eye so that eye is entered posterior to the iris root at the lens plane); ocutome blade sclerotomy and anterior capsulotomy; mechanical cutting/aspiration of lens substance, posterior capsule, and anterior vitreous; 8-0 vicryl closure sclera and conjunctiva; topical atropine 1% drop; and the application of a patch and shield. A second pars plicata incision for placement of infusion line has more recently been adopted and is preferred so that all instruments remain far from the endothelium.
Postoperatively, atropine 1% drops were prescribed twice daily for 6 weeks. All patients were fitted postoperatively with contact lenses and examined as often as necessary during the first 3 weeks to ensure adequate contact lens fit and family compliance. The children were re-examined and re-refracted every 3 weeks for 3 months, and then every 3 months until age 5 years. In the unilaterally affected children, the phakic eye was patched for 12 hours every other day beginning 1 week after regular contact lens wear was established, or as soon as contact lens management was assured. In eight eyes (four patients), fluorescein angiography was performed under anesthesia within 2 weeks and again at 3 months after cataract surgery.
During the study period, cataracts were removed from 52 eyes in 37 patients who met the study criteria. Sixteen patients were bilaterally affected. In one of these, only one eye was included in the present study since the second cataract was removed in 1988. Of the 21 unilaterally affected patients, 11 (52%) had cataracts in the right eye, 10 (48%) in the left. Most patients (29) had normal birth and development histories. Eight patients, six of whom were bilaterally affected, were mentally or developmentally impaired but had no additional ocular anomaly other than possible microphthalmos. Of the 37 patients, 34 were white, two were black, and one was of Indian descent but Canadian-born. Their ages at surgery ranged from 2 weeks to 4.5 years, with a median of 5 months. Duration of follow-up ranged from 1.5 years to 7 years, with a median of 4 years. In 15 of the 37 patients, repeatable Snellen linear acuities were obtained.
Thirty-four eyes had total cataracts; 25 of these were in bilaterally affected patients. Eighteen eyes had partial cataracts; six of these were in bilaterally affected and 12 in unilaterally affected patients. Complete cataracts were defined as those that allowed no view of the posterior pole with an indirect ophthalmoscope but did not necessarily imply opacity involving all of the lens substance. Partial cataracts were those that obscured the media to the degree that fundus details could not be appreciated with a direct ophthalmoscope or in which there was a limited central opacity not less than 3 mm in diameter.
Many of the cataracts were presumably of congenital onset by history and presentation, but because none was actually detected at birth, we have chosen to use the more inclusive term "developmental."
Six eyes were clinically identified as microphthalmic because of the small appearance of the globes compared with the contralateral eyes. These eyes were otherwise normal with deep chambers and normal fundi.
We detected no early surgical complications. In eight eyes evaluated with intravenous fluorescein angiogram performed within 2 weeks and 3 months of cataract extraction, there was no cystoid macular edema (CME). We detected no hyphemas, vitreous hemorrhages, retinal detachments, or glaucoma during the first postoperative examination under anesthesia at the time of contact lens fitting.
Secondary membranes developed 2 to 4 months postoperatively in six eyes in patients who were less than 2 months old at the time of surgery. These six eyes had axial lengths 5S 17.4 mm, and corneal diameters *£ 9.5 mm. Membranes developed in 55% of eyes of these dimensions, but in none of the larger eyes. Mean axial lengths and corneal diameters in the eyes that developed membranes and a comparative subgroup of infant eyes in which cataracts were removed prior to 2 months of age are presented in the Table. Each eye that developed a membrane required one reoperation to clear the visual axis. Visual results are uniformly poor in these six eyes; they all lack central, steady, and maintained fixation.
Four of the six eyes that developed membranes had been clinically identified as microphthalmic, but two other eyes that were small by absolute dimensions (axial length =£ 17.4 mm, corneal diameter « 9.5 mm) but had not appeared relatively smaller than the contralateral eyes, also developed membranes. Conversely, two eyes that had appeared smaller than the contralateral eyes and were thus clinically labelled microphthalmic were actually of larger dimensions than those cited here and did not develop membranes.
Patient ages at surgery ranged from 0.5 months to 54 months. Bilateral cataracts were removed at an earlier age than were unilateral cataracts, and total cataracts were removed at an earlier age than were partial cataracts. Mean ages at surgery were 3 and 5 months for total and partial bilateral cataracts respectively compared to 18 and 25 months for bilateral and unilateral partial cataracts, respectively.
Comparative Ocular Dimension in Study Subgroups
Fifteen patients were mature enough to respond to linear Snellen acuity testing. In 11 of these (75%), contact lens compliance was good (at least three quarters of the time). Two bilaterally affected children are wearing aphakic spectacles. Patching compliance was good (halftime) in four of the nine unilaterally affected patients (44%).
Visual results in six eyes with complete cataracts (three bilaterally affected patients) ranged from 20/25 to 20/80, with a median of 20/50. In six eyes with partial cataracts (three bilaterally affected patients), visual acuity ranged from 20/20 to 20/80, with a median of 20/40. Four of six patients had no more than two lines difference between the two affected eyes. Two patients had a preferred eye with a 20/80 strabismic, amblyopic eye. One of these had total cataracts and a preoperative esotropia (the amblyopic eye having turned preoperatively). The other, who had partial cataracts, underwent cataract extraction in the second (now amblyopic) eye 3 months after the first procedure. In four patients with unilateral complete cataracts, visual acuities ranged from 20/60-CF, with a median of 20/400. In five patients with unilateral partial cataracts, visual acuity ranged from 20/30 to 20/400, with a median of 20/200.
Surgical results of pediatric cataract extraction have dramatically improved since Barkan described simple discission in 19325 and Owens and Hughes reported results of linear extraction in 1948.6 Needling and aspiration, which were repopularized by Scheie in I9607 and led to reduced complication rates and improved results, were adopted by many pediatric ophthalmologists810 with improved surgical results. Phacoemulsification has also been employed to remove infantile cataracts,11 but with a high rate of secondary membrane formation.
The use of automated vitrectors in pediatric cataract extraction, as described by Calhoun and Harley in 1975,3 has greatly advanced the surgical management of pediatric cataracts. Two main approaches, through the limbus2 or through the pars plicata,5 are currently employed. In 1981, Hoyt and Nickel12 reported an increased incidence of postoperative CME in eyes undergoing limbal Iensectomy/ vitrectomy (10 of 27 eyes, 6 persistent) compared with those undergoing discission and aspiration (1 of 27 eyes).
In 1982, Gilbard et al13 found no postoperative CME on fluorescein angiogram in 25 eyes (with the exception of one eye with questionable grade 1 CME on FA) after pars plicata lensectomy/vitrectomy. They suggested that the absence of CME in their patients might be related to reduced prostaglandin release and inflammation resulting from less iris manipulation intraoperatively, and the presence of less residual cortex postoperatively. Moreover, they emphasized that the pars plicata approach precludes vitreous incarceration in a limbal wound, which was observed by Taylor14 in 5 (23%) of 23 eyes undergoing limbal lensectomy/vitrectomy.
Taylor found that no reoperations were necessary to maintain a clear pupillary axis in 23 eyes undergoing lensectomy/vitrectomy, whereas 32 reoperations were needed in 28 eyes undergoing simple aspiration when the posterior capsule was left intact. He noted that repeated operations during the first 18 months of life, which is a critical period for visual development, greatly increased the risk of developmental amblyopia. Thus, Parks15 has argued that the risk of amblyopia is greater than the risk of CME, and therefore the posterior capsule should be removed in all cases.
Reported results indicate that the pars plicata lensectomy/vitrectomy offers the greatest chance for a sustained clear visual axis and the least likelihood of postoperative inflammation and CME. Our experience supports this view. We detected no hyphemas, vitreous hemorrhages, . retinal detachments, or glaucomas. No early postoperative complication precluded refraction and optical correction. There was no postoperative CME on intravenous fluorescein angiogram in eight eyes and no appreciated clinical CME throughout the 1.5- to 7-year follow-up period.
Secondary membrane formation occurred in 6 of 52 eyes (12%) from 2 to 4 months after cataract extraction. Each eye required one reoperation to keep the pupillary axis clear. Eyes at risk of developing secondary membranes were those small by absolute standards. Although each eye required one reoperation, performed at a mean age of 6 months and a mean duration of 3 months after primary cataract extraction, the period of visual deprivation probably spanned a considerable part of the first 6 months of hie. The visual results in these eyes are uniformly poor; all of the eyes currently lack central, steady, and maintained fixation. It is possible that these six small eyes had unappreciated associated ocular anomalies, but repeated examinations revealed none. It should be noted that two eyes that had been clinically identified as microphthalmic were relatively small compared with the larger contralateral eyes but were not small by the absolute criteria suggested here and did not develop membranes. Therefore, we suggest that suspected risk of secondary membrane development be evaluated on the basis of absolute rather than relative dimensions. One can speculate about the mechanism that puts smaller eyes at risk of secondary membrane formation. It could be related to total eye volume, in which case axial length might be the most predictive dimension. It might be related to anterior chamber dimensions only, in which case corneal diameter and anterior chamber depth might be most predictive. In that case, diminished axial length would reflect diminished anterior chamber depth.
Visual results in 15 patients who were mature enough to respond to linear Snellen acuity testing support the findings cited by Parks.12 Those bilaterally affected have better visual outcomes than those unilaterally affected. Those with total cataracts presented earlier but had a poorer outcome than those with partial cataracts, who presented later and had better visual outcomes. It is likely that those with partial cataracts, even those noted at birth, are afforded some early period of visual development prior to progression of the cataract. However, this is not an argument for deferring surgery in those with partial cataracts that are visually significant, especially in the unilaterally affected patients in whom irreversible preference can develop.
Although not documented in detail here, visual results were best in patients whose cataract(s) were removed at the earliest opportunity once a significant opacity had been appreciated and in those who tolerated optical correction and occlusion (in the unilateral cases) well. When cataract extraction was delayed, aggressive postoperative visual rehabilitation did not reverse the effects of critical early deprivation. These are consistent with the findings of Parks.12
Median visual acuities in patients with unilateral cataracts are poor, although individual good results can be cited. One patient with a total unilateral cataract removed at 1 month of age and aggressively patched half-time for 6 years has 20/60 vision. Another patient with a unilateral partial cataract removed at 8 months of age and aggressively patched in the same fashion has 20/30 vision. Neither has binocular vision. Overall, the visual results in unilateral cataracts reviewed in this study remain poor. More centers have reported improved visual results after monocular cataract extraction,16-18 arguing for continued early removal and refinement of postoperative visual rehabilitation regimens.
The procedure and management plan required for optimal visual rehabilitation after pediatric cataract extraction is one that offers the least risk of both early and late surgical complications and allows sustained clearance of the visual axis and refractive correction. The pars plicata approach with removal of the posterior capsule and anterior vitreous offers a simple, effective means of maintained clearance of the visual axis with minimal surgical risk, rapid healing, and early visual rehabilitation.
1. Parks MM. Visual results in aphakic children. Am J Ophthalmol. 1982;94:441-449.
2. Parks MM. Management of cataracts in infants. In: New Orleans Academy of Ophthalmology Staff, eds: Pediatric Ophthalmology and Strabismus: Transactions of the New Orleans Academy of Ophthalmology . New York: Raven Press; 1986:119-139.
3. Calhoun JH, Harley RD. The roto-extractor in pediatric ophthalmology. Trans Am Ophthalmol Soc. 1975;73:292-305.
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7. Scheie HG. Aspiration of congenital or soft cataracts: A new technique. Am J Ophthalmol. 1960;50:1048-1056.
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9. Ryan SJ, von Noorden GK. Further observations on the technique in aspiration of cataract surgery. Am J Ophthalmol. 1971;71:626-630.
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11. Hiles DA, Wallar PH. Phacoemulsification versus aspiration in infantile cataract surgery. Ophthalmic Surg. 1974;(5): 13-16.
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13. Gilbard SM, Peyman GA, Goldberg MF. Evaluation for cystoid maculopathy after pars plicata lensectomy-vitrectomy for congenital cataracts. Ophthalmology. 1983;90:1201-1206.
14. Taylor D. Choice of surgical technique in the management of congenital cataract. Transactions of the Ophthalmological Society ot the United Kingdom. 1981;101:114-117.
15. Parks MM. Posterior lens capsulectomy during primary cataract surgery in children. Ophthalmology. 1983;90:344.
16. Beller R, Hoyt CS, Marg E, Odom JV. Good visual function after neonatal surgery for congenital monocular cataracts. Am J Ophthalmol. 1981;91:559-565.
17. Birch EF, Stager DR. Prevalence of good visual acuity following surgery for congenital unilateral cataract. Arch Ophthalmol. 1988;106:40-43.
18. Drummond GT, Scott WE, Keech RV. Management of monocular congenital cataracts. Arch Ophthalmol. 1989;107:45-51.
Comparative Ocular Dimension in Study Subgroups