Manifestations of persistent pupillary membrane

Abstract

Purpose: To study the clinical and structural manifestations of persistent pupillary membranes (PPM) using light and electron microscopy.

Materials and methods: This descriptive case series study included 32 children (38 eyes) with different clinical PPM types. The cases were collected between 2005 and 2023. The age of the patients ranged from 7 months to 13 years, with a mean age of 3 ± 2.6 years. All children underwent standard ophthalmological examinations, including biomicroscopy, keratometry, gonioscopy, ophthalmoscopy, tonometry, visometry, ultrasonic biometry, scanning, and photo and video recording. Surgical removal of PPM was performed in 15 children (17 eyes), and the removed PPMs were histologically and electron microscopically studied.

Results: The PPMs were of different sizes, configurations, and volumes. The vast majority, 25 children (29 eyes, 76.3%), had type II PPM with iridolenticular attachment (Duke-Elder classification, 1964). Six children (8 eyes, 21.1%) had type I PPMs with iris-to-iris attachment. In one case (one eye, 2.67%), a combination of type I and type II PPM was observed. In the eyes with PPM, microphthalmia and microcornea were observed in 34.2% and 23.7% of cases, respectively. PPM affected the size and configuration of the pupil in 44.76% of cases and the anterior chamber angle structure in 26.3% of cases. The lens remained transparent in 84.2% of the cases. Congenital cataracts were observed in 15.89%. Visual acuity in the eyes with PPM varied from light perception to 0.4 logMAR. In 50.0% of cases, significant visual loss occurred in type II PPM. Histomorphological and electron microscopic studies showed that PPM was the remnant of the tunica vasculosa lentis, had a mesodermal origin, and did not penetrate the anterior lens capsule.

Conclusion: For the first time, the clinical features of PPM were analyzed in a significantly large number of cases, and the analysis showed that PPMs with iridolenticular attachment were dominant. They were of different sizes and configurations and had a dense fit to the lens, causing significant visual loss and thus requiring surgical removal. In almost half of the cases, PPM caused pupil narrowing, decentration, and deformation, whereas the crystalline lens remained transparent in most cases (84.2%).