Journal of Pediatric Ophthalmology and Strabismus

Outcome of Hyperplastic Persistent Pupillary Membrane

Sang Mok Lee, MD; Young Suk Yu, MD

Abstract

ABSTRACT

Purpose: To evaluate the long-term visual outcome of eyes with hyperplastic persistent pupillary membrane.

Patients and Methods: We adopted a retrospective approach involving 39 eyes of 24 Korean patients diagnosed as having hyperplastic persistent pupillary membrane, excluding patients who could not be observed beyond 3 years of age and eyes that had any other ocular anomalies that affect vision. Final best-corrected visual acuity and refractive status were compared according to treatment type and laterality. Mean visual acuity was transformed to the logarithm of the minimum angle of resolution (logMAR).

Results: The mean final best-corrected visual acuity was 0.32 (standard deviation, ± 0.41). Five eyes had a best-corrected visual acuity less than 20/70 at the last follow-up. Four eyes were unilateral (deprivation amblyopia) and one eye was bilateral (anisometropic amblyopia). There were no significant differences in final best-corrected visual acuity according to treatment type or laterality. Significant anisometropia was found in 11 of the 24 patients. The mean absolute value of anisometropia was greater in the surgical treatment group than in the medical treatment and observation groups (P = .048).

Conclusions: The visual prognoses for individuals with hyperplastic persistent pupillary membrane can be relatively good if the condition is appropriately managed. Unilaterality and poor initial visual acuity are indicators of a poor visual outcome. Surgery is effective when the opaque membrane retards visual maturation. Close follow-up with evaluation of visual acuity and refractive status is mandatory because this condition can lead to deprivation amblyopia and anisometropic amblyopia.

J Pediatr Ophthalmol Strabismus 2004;41:163-171.

Abstract

ABSTRACT

Purpose: To evaluate the long-term visual outcome of eyes with hyperplastic persistent pupillary membrane.

Patients and Methods: We adopted a retrospective approach involving 39 eyes of 24 Korean patients diagnosed as having hyperplastic persistent pupillary membrane, excluding patients who could not be observed beyond 3 years of age and eyes that had any other ocular anomalies that affect vision. Final best-corrected visual acuity and refractive status were compared according to treatment type and laterality. Mean visual acuity was transformed to the logarithm of the minimum angle of resolution (logMAR).

Results: The mean final best-corrected visual acuity was 0.32 (standard deviation, ± 0.41). Five eyes had a best-corrected visual acuity less than 20/70 at the last follow-up. Four eyes were unilateral (deprivation amblyopia) and one eye was bilateral (anisometropic amblyopia). There were no significant differences in final best-corrected visual acuity according to treatment type or laterality. Significant anisometropia was found in 11 of the 24 patients. The mean absolute value of anisometropia was greater in the surgical treatment group than in the medical treatment and observation groups (P = .048).

Conclusions: The visual prognoses for individuals with hyperplastic persistent pupillary membrane can be relatively good if the condition is appropriately managed. Unilaterality and poor initial visual acuity are indicators of a poor visual outcome. Surgery is effective when the opaque membrane retards visual maturation. Close follow-up with evaluation of visual acuity and refractive status is mandatory because this condition can lead to deprivation amblyopia and anisometropic amblyopia.

J Pediatr Ophthalmol Strabismus 2004;41:163-171.

INTRODUCTION

The pupillary membrane is formed by buds from the annular vessel of the iris that grow centrally to form the anterior vascular tunic of the lens.1,2 Persistent pupillary membrane is formed as a consequence of incomplete involution and atrophy of the pupillary membrane. Waardenburg et al.2 reported that remnants of the embryonic vasculature are found in 80% of dark eyes and 35% of light eyes.

Table

TABLE 1REVIEW OF THE LITERATURE ON HYPERPLASITC PERSISTENT PUPILLARY MEMBRANE

TABLE 1

REVIEW OF THE LITERATURE ON HYPERPLASITC PERSISTENT PUPILLARY MEMBRANE

Table

TABLE 1REVIEW OF THE LITERATURE ON HYPERPLASITC PERSISTENT PUPILLARY MEMBRANE

TABLE 1

REVIEW OF THE LITERATURE ON HYPERPLASITC PERSISTENT PUPILLARY MEMBRANE

Most persistent pupillary membranes require no treatment because they usually undergo considerable atrophy during the first year of life and only rarely cause visual impairment.3,4 Remnant structures vary from a few nonpigmented threads, which are probably vestiges of precursor vessels, to a thick membrane covering the entire pupil.5 The latter condition has been called hyperplastic persistent pupillary membrane, enlarged pupillary membranes, or hyperplasia of the iris.4"6 These hyperplastic opaque membranes can persist and obscure the pupillary opening, and may be dense enough to decrease vision and produce deprivation amblyopia. Medical and surgical management for extensive membrane has been reported.5"9 However, previous reports on hyperplastic persistent pupillary membrane have been case reports and have not described the long-term visual prognosis of this condition (Table 1).

In this study, we reviewed the medical records of 39 eyes with hyperplastic persistent pupillary membrane not associated with any other ocular anomaly affecting visual outcome and evaluated die visual prognosis and refractive change.

PATIENTS AND METHODS

We reviewed the medical records of 34 Korean patients (52 eyes) who had been diagnosed as having hyperplastic persistent pupillary membrane at the Ocular Congenital Anomaly Clinic of Seoul National University Children's Hospital from 1987 to 1999. Hyperplastic persistent pupillary membrane was diagnosed from the presence of a thick membrane covering die pupil, arising from and inserting into the iris collarette. None of the hyperplastic persistent pupillary membranes in this study showed regression during the follow-up period. Patients who could not be observed after 3 years of age and eyes that had other ocular anomalies affecting visual outcome were excluded. Three patients with monocular hyperplastic persistent pupillary membrane were excluded because they were not observed after 3 years of age. One patient with monocular hyperplastic persistent pupillary membrane was excluded due to loss of follow-up for 5 years until the age of 7 without any recommended treatment during this period. One patient with bilateral hyperplastic persistent pupillary membrane was excluded because of loss of follow-up after surgery recommendation. Seven eyes of 5 patients were excluded due to combined ocular anomalies that could have affected the visual outcome. In terms of combined ocular anomalies, congenital cataract existed in 4 eyes of 3 patients; persistent hyperplastic primary vitreous existed in 1 eye of 1 patient; and retinal fold with high myopia and nystagmus existed in both eyes of 1 patient. Thirtynine eyes of 24 patients remained after these exclusions. The visual acuity at the first visit, treatment method, final visual acuity, final refractive state, and surgical complications were reviewed.

Table

TABLE 2CLINICAL DATA OF 24 KOREAN PATIENTS (39 EYES) WITH HYPERPLASTIC PERSISTENT PUPILLAY MEMBRANE

TABLE 2

CLINICAL DATA OF 24 KOREAN PATIENTS (39 EYES) WITH HYPERPLASTIC PERSISTENT PUPILLAY MEMBRANE

Table

TABLE 2CLINICAL DATA OF 24 KOREAN PATIENTS (39 EYES) WITH HYPERPLASTIC PERSISTENT PUPILLAY MEMBRANE

TABLE 2

CLINICAL DATA OF 24 KOREAN PATIENTS (39 EYES) WITH HYPERPLASTIC PERSISTENT PUPILLAY MEMBRANE

The eyes were divided into three groups according to treatment modality: a surgical treatment group, a medical treatment group, and an observation group. Surgical indications included poor visual acuity of 3 lines or more as compared with the contralateral eye, and a best-corrected visual acuity of less than 20/70 in both eyes. Medical treatment solely was instituted until 1 year of age. Surgery was chosen when there was no improvement or some deterioration of visual acuity with medical treatment. However, two patients underwent surgery before 1 year of age due to severity of the persistent pupillary membrane. Surgery was performed using vitreous scissors.9 Mydriasis, occlusion, or both were prescribed for patients who had some difference in visual acuity between their eyes, although these differences were smaller than those in the surgical treatment group, or in those who had a small pupillary aperture of less than 1.5 mm in diameter that could be dilated by mydriatics.

Eyes were further classified into bilateral and unilateral groups to evaluate the visual outcome. However, some bilateral cases with marked asymmetry may show clinical courses similar to those of unilateral cases; therefore, we also classified the eyes into symmetric and asymmetric groups. The symmetric group consisted of patients with persistent pupillary membrane that was morphologically similar in both eyes, and the asymmetric group included both unilateral cases and markedly asymmetric bilateral cases.

Best-corrected visual acuity and refractive status were compared according to laterality and treatment. Significant anisometropia was defined as spherical myopic anisometropia of more than 2 D, spherical hypermetropic anisometropia of more than 1 D, or cylindrical anisometropia of more than 1.5 D. These thresholds were chosen because more severe anisometropia results in an increased incidence and severity of amblyopia.10

Table

TABLE 3MEAN BEST-CORRECTED VISUAL ACUITY ACCORDING TO TREATMENT AND LATERALITY

TABLE 3

MEAN BEST-CORRECTED VISUAL ACUITY ACCORDING TO TREATMENT AND LATERALITY

Table

TABLE 4PATIENTS WITH ANISOMETROPIA CAUSING AMBLYOPIA

TABLE 4

PATIENTS WITH ANISOMETROPIA CAUSING AMBLYOPIA

Refractive power was expressed in terms of the spherical equivalent after cycloplegic refraction, visual acuity was checked using the Snellen chart, and mean visual acuity was calculated using the logarithm of the minimum angle of resolution (logMAR).

SPSS software (version 10.0 for Windows; SPSS, Inc., Chicago, IL) was used for statistical analysis. The Kruskal- Wallis test was used for comparison among three groups and the Mann- Whitney test was used for comparison between two groups.

RESULTS

The clinical data of the 39 eyes are summarized in Table 2.

Among the 39 eyes of the 24 patients, the surgical treatment group consisted of 12 eyes, the medical treatment group consisted of 1 1 eyes, and the observation group consisted of 16 eyes. According to laterality, 15 patients had bilateral hyperplastic persistent pupillary membrane and 9 had unilateral hyperplastic persistent pupillary membrane. The asymmetric group consisted of 9 unilateral and 4 bilateral asymmetric cases. The mean age at the first visit was 3.7 years (standard deviation [SD], ± 3.8 years; range, 5 weeks to 13.6 years), the mean age at the last visit was 6.9 years (SD, ± 3.0 years; range, 3.1 to 13.7 years), and the mean follow-up period was 3.3 years (SD, ± 2.3 years; range, 0 to 7.8 years).

Final best-corrected mean visual acuity was 0.32 (SD, ±0.41) (20/43, Snellen visual acuity). No significant differences were evident regarding bestcorrected visual acuity among the three treatment groups (P = .401) nor between the two laterality groups (P = .107) (Table 3). The final best-corrected visual acuities of 5 of the eyes were less than 20/70, and these were the only eyes with visual acuities two lines or more worse than those in the contralateral eyes. Significant anisometropia was found in 1 1 of the 24 patients (Table 4).

The mean absolute value of spherical anisometropia was similar in the unilateral and bilateral groups (P= .446) and between the symmetric and asymmetric groups (P= .106) (Table 5). However, the mean absolute value of spherical anisometropia differed significantly among the three treatment groups (P= .048) (Table 5). The mean spherical anisometropia in the asymmetric group was -0.38 D.

During the postoperative period of the surgical treatment group, one patient had a mild cataract in one eye (patient 1), one had a fibrous membrane on the anterior lens capsule in one eye (patient 2), and seven had significant anisometropia (patients 1, 2, 4,5, 10, 13, and 15).

DISCUSSION

Persistent pupillary membrane arises from and inserts into the iris collarette and is thereby distinguished from congenital idiopathic microcoria or congenital pupillary- iris- lens membrane, in which there is no distinct membrane attached to the collarette.11'13

Persistent pupillary membrane is usually an isolated finding, although the condition has been reported to occur in a familial manner in association with other ocular anomalies such as cataract, glaucoma, microphthalmos, microcornea, megalocornea, aniridia, iris coloboma, strabismus, nystagmus, ectopia lentis et pupillae, and ametropia.13"18 Most of these lesions produce no problematic symptoms. A rare exception is spontaneous hyphema, which occurs later in life from a strand of vascularized pupillary membrane.19,20

However, the hyperplastic type of persistent pupillary membrane can produce deprivation amblyopia.5 A pupillary opening of less than 1.5 mm can produce a significant decrease in visual acuity because of diffraction and, less importantly, decreased retinal illumination.5 Hence, many ophthalmologists have tried to construct a pupillary opening in these cases to prevent deprivation amblyopia. Miller and Judisch reported a case of successful management of a severe unilateral persistent pupillary membrane with mydriasis and occlusion therapy.5 Successful surgical removal of the membrane was reported by Levy3 and Merin et al.4 However, despite their surgical successes, neither patient achieved 20/20 vision. Reynolds et al. suggested that prompt therapeutic intervention within the first few weeks or months of life is necessary to prevent amblyopia.6 Surgical excision, however, has its own complications such as hyphema and cataracts in addition to the risk of anesthesia and infection.14,21

In our study, one mild cataract and one fibrous membrane on the anterior lens capsule occurred as a complication among 12 surgically treated eyes. Vega and Sabates7 and Kumar et al.8 reported successful neodymium-YAG laser treatment for persistent pupillary membrane. However, some patients with hyperplastic persistent pupillary membrane may have a normal visual outcome without any treatment.22'24 In this study, 17 of 39 eyes had an initial visual acuity of more than 20/40 or good fix and follow. In some patients, surgery was performed for cosmetic reasons despite possible complications.13 Some patients with hyperplastic persistent pupillary membrane may complain of decreased visual acuity in bright sunlight despite normal visual acuity on routine office examination. In these patients, a simulated sunlight test by shining an indirect ophthalmoscope light from an oblique (45°) angle may help to determine a treatment plan if there is normal vision.8,14,25 However, such a simulated sunlight test was not performed on the patients in our study.

Table

TABLE 5MEAN ABSOLUTE VALUE OF ANISOMETROPIA ACCORDING TO LATERALITY, SYMMETRY, AND TREATMENT

TABLE 5

MEAN ABSOLUTE VALUE OF ANISOMETROPIA ACCORDING TO LATERALITY, SYMMETRY, AND TREATMENT

Unilateral hyperplastic persistent pupillary membrane is an important indicator of poor visual outcome, although in this study, the final mean visual acuity was not significantly different between the unilateral and bilateral groups. There were 9 unilateral cases, all of which presented before 11 months of age, and 7 with poor vision. Four ended up with vision of 20/200 or less despite surgery. Of the 3 who finally gained normal vision, 1 underwent surgery and 2 were treated with occlusion and mydriatics.

There were 15 bilateral cases, 4 of which had an initial visual acuity difference of 2 lines or more. Amblyopia occurred due to deprivation in 3 patients and anisometropia in 1 patient (patient 15, as discussed below). The 3 patients with deprivation amblyopia finally gained normal vision by surgery (patients 12 and 13) and occlusion (patient 18).

Finally, the best-corrected visual acuity of 5 of the 39 eyes was less than 20/70. All underwent surgery within 12 months and 4 were unilateral cases. Poor visual outcome was associated with an initial poor fixation pattern and unilaterality in these 4 patients. A single, bilateral case (the left eye of patient 1 5) underwent surgery when the patient was 6 years old, due to the late discovery of amblyopia. However, this amblyopia might have been caused by the patient's severe spherical myopic anisometropia (-11.0 D) rather than by the hyperplastic persistent pupillary membrane because the persistent pupillary membranes in the patient's eyes appeared to be morphologically similar (Figure). Nevertheless, surgical intervention was tried to accelerate the effects of the occlusion therapy, and this led to some mild improvement in vision (finger counting, 20 cm to 20/100).

Figure. Patient 15: (A) right eye preoperatively; (B) left eye preoperatively; and (C) left eye postoperatively. The patient was first examined in our clinic when he was 5.9 years old. His vision was 20/30 (right eye) and finger counting at 20 cm (left eye). His fundus showed no specific abnormality (right eye) and myopic degeneration (left eye). The pupillary membranes in both eyes appeared to be similar. His amblyopia might have been caused by severe spherical myopic anisometropia and myopic degeneration. His left eye underwent surgery and occlusion therapy. His refractive status was emmetropia (right eye) and -14.5 sphere -2.5 cylinder x 180° (left eye) after surgery. His left final bestcorrected visual acuity 2.8 years after treatment was 20/100.

Figure. Patient 15: (A) right eye preoperatively; (B) left eye preoperatively; and (C) left eye postoperatively. The patient was first examined in our clinic when he was 5.9 years old. His vision was 20/30 (right eye) and finger counting at 20 cm (left eye). His fundus showed no specific abnormality (right eye) and myopic degeneration (left eye). The pupillary membranes in both eyes appeared to be similar. His amblyopia might have been caused by severe spherical myopic anisometropia and myopic degeneration. His left eye underwent surgery and occlusion therapy. His refractive status was emmetropia (right eye) and -14.5 sphere -2.5 cylinder x 180° (left eye) after surgery. His left final bestcorrected visual acuity 2.8 years after treatment was 20/100.

Figure. Patient 15: (A) right eye preoperatively; (B) left eye preoperatively; and (C) left eye postoperatively. The patient was first examined in our clinic when he was 5.9 years old. His vision was 20/30 (right eye) and finger counting at 20 cm (left eye). His fundus showed no specific abnormality (right eye) and myopic degeneration (left eye). The pupillary membranes in both eyes appeared to be similar. His amblyopia might have been caused by severe spherical myopic anisometropia and myopic degeneration. His left eye underwent surgery and occlusion therapy. His refractive status was emmetropia (right eye) and -14.5 sphere -2.5 cylinder x 180° (left eye) after surgery. His left final bestcorrected visual acuity 2.8 years after treatment was 20/100.

Figure. Patient 15: (A) right eye preoperatively; (B) left eye preoperatively; and (C) left eye postoperatively. The patient was first examined in our clinic when he was 5.9 years old. His vision was 20/30 (right eye) and finger counting at 20 cm (left eye). His fundus showed no specific abnormality (right eye) and myopic degeneration (left eye). The pupillary membranes in both eyes appeared to be similar. His amblyopia might have been caused by severe spherical myopic anisometropia and myopic degeneration. His left eye underwent surgery and occlusion therapy. His refractive status was emmetropia (right eye) and -14.5 sphere -2.5 cylinder x 180° (left eye) after surgery. His left final bestcorrected visual acuity 2.8 years after treatment was 20/100.

Anisometropia, not only myopic but also hyperopic, was shown to be more prevalent among the patients in this study, and eyes with morphologically more severe hyperplastic persistent pupillary membrane were found to be more ametropic. The mean absolute value of spherical anisometropia differed significandy between the surgical and nonsurgical treatment groups (Table 5). This result suggests that more severe occlusion by hyperplastic persistent pupillary membrane in the neonatal period can cause more severe ametropia associated with either a myopic, hyperopic, or cylindrical trend.

Consideration needs to be given to the possibility of an improved outcome if the patients had undergone surgery earlier, within the first few weeks of life, as suggested by Reynolds et al.6 In our study, although the pupil of patient 4 could not be dilated during the first visit, surgery was delayed for 4 months with occlusion therapy. This patient may have benefited from earlier surgery. As for patienr 2, the pupil could be dilated, so she was treated with mydriatics and occlusion therapy for approximately 1 1 months with good compliance. However, due to a deterioration of the fixation pattern, surgery was performed when this patient was 12 months old, and she probably would not have benefited from earlier surgery. Patients 3 and 5 were examined at 6 and 1 1 months of age, respectively, and underwent surgery at the earliest opportunity. However, when a pupil with hyperplastic persistent pupillary membrane will not dilute well with mydriatics, it remains advisable to perform surgery within the first few weeks of life if possible, despite the possible complications.613

To the best of our knowledge, this is the first comprehensive study (39 eyes) with follow-up to beyond 3 years of age for eyes with hyperplastic persistent pupillary membrane. It is critical that clinicians remain keenly aware of pupillary status, visual acuity, and refractive status to avoid the potential development of deprivational and anisometropic amblyopia. If hyperplastic persistent pupillary membrane is appropriately managed, the visual prognosis can be relatively good. Surgery must be considered within the first few weeks if the pupil does not respond to mydriasis.

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TABLE 1

REVIEW OF THE LITERATURE ON HYPERPLASITC PERSISTENT PUPILLARY MEMBRANE

TABLE 1

REVIEW OF THE LITERATURE ON HYPERPLASITC PERSISTENT PUPILLARY MEMBRANE

TABLE 2

CLINICAL DATA OF 24 KOREAN PATIENTS (39 EYES) WITH HYPERPLASTIC PERSISTENT PUPILLAY MEMBRANE

TABLE 2

CLINICAL DATA OF 24 KOREAN PATIENTS (39 EYES) WITH HYPERPLASTIC PERSISTENT PUPILLAY MEMBRANE

TABLE 3

MEAN BEST-CORRECTED VISUAL ACUITY ACCORDING TO TREATMENT AND LATERALITY

TABLE 4

PATIENTS WITH ANISOMETROPIA CAUSING AMBLYOPIA

TABLE 5

MEAN ABSOLUTE VALUE OF ANISOMETROPIA ACCORDING TO LATERALITY, SYMMETRY, AND TREATMENT

10.3928/0191-3913-20040501-09

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