‘Camouflaged catastrophe’ hides in some infantile cataracts

A broken posterior capsule may not be apparent on undilated examination.

Issue: October 1, 2001

ByRaminder Singh, MS

ByAbhay R. Vasavada, MS, FRCS

ByAlpesh Shah, MS

The condition we call “camouflaged catastrophe” manifests among infants and small children as a congenital cataract with an existing defect in the posterior capsule.

Classically the catastrophe is hidden behind a seemingly routine pediatric cataract. When seen through a normal-sized, undilated pupil, it appears to be a totally white cataract (figure 1).

Dilation revealed a posterior capsule defect. The inset shows the appearance of a totally white cataract through an undilated pupil.	The pre-existing posterior capsule defect demarcated by a thickened margin and white dots.
White granules are located within the vitreous — a “fishtail sign.”

It is easy to be misled by this appearance. If the surgeon deals with it like a normal cataract and performs hydrodissection, the lens substance is mixed with the vitreous and leads to deleterious consequences. The sudden buildup of hydraulic pressure can enlarge the defect and threaten the stability of the capsular bag.

This is particularly of grave concern in a pediatric eye, where a technically perfect outcome is mandatory for lifelong maintenance. Unlike in adults, the consequences of imperfect management may not be noticeable for several years.

This condition is different from posterior polar cataract seen in adults, which is easily recognizable by its characteristic appearance and well-established clinical profile.

How should a surgeon approach a child with such a condition?

Approaching the catastrophe

First and foremost is preoperative evaluation under anesthesia after maximal dilatation. This is a must because only a dilated pupil unveils the important diagnostic signs of an existing posterior capsule (PC) defect.

What are the diagnostic signs?

The characteristic demarcation of the PC defect by white dots and thickened margin is the hallmark of this entity (figure 2).

On moving the globe with forceps, the degenerated vitreous with white granules moves like a fishtail. We call this the fishtail sign (figures 3a and 3b). This is pathognomonic of a pre-existing PC defect.

The presence of white dots behind the cataractous lens has been described by Dr. Daljit Singh.

Careful B-scan ultrasonography and ultrasound biomicroscopy (UBM) would reveal these changes.

Counseling of parents is extremely helpful. This should include explaining the nature of the disease, the potential difficulties arising during surgery and postoperative management.

Complying with the following surgical paradigms should result in a predictable and satisfactory outcome:

Anterior capsulorrhexis is the sheet anchor of the surgical paradigms for lens removal and IOL fixation.
Hydrodissection should never be attempted.
Bimanual irrigation and aspiration is not only invaluable for thorough removal of the lens matter but also for delaying the dreaded catastrophe.
It is crucial to adhere to the principles of closed-chamber technique by injecting a viscoelastic into the anterior chamber before removing an instrument from the eye.
Performing adequate vitrectomy is mandatory. Appropriately reduced aspiration parameters during cortex and vitreous removal induce minimal turbulence and allow us to achieve absolute control.

Prevalence

In our pediatric population we found the prevalence of ruptured PC to be 7%. Therefore we cannot overemphasize the value of diagnosing the demarcation of the PC defect by the presence of white dots.

Microscopic exploration

What are these white dots composed of?

We collected some of these white granules during vitrectomy. We also collected a ribbon of posterior capsule with adherent white dots. The samples were stained with a calcium-specific staining technique. This revealed a large accumulation of calcium in the granules. Phase contrast microscopy and scanning electron microscopy of the posterior capsule revealed an altered and irregular lamellar arrangement of collagen fibrils.

Based on these findings and our clinical experience, we speculate that this birth defect perhaps begins as a posterior lenticonus. However, unlike the classical posterior lenticonus, the process continues at an accelerated pace and terminates in a full-blown defect.

For your information

Abhay R. Vasavada, MS, FRCS is the director of the Iladevi Cataract and IOL Research Centre.

Raminder Singh, MS, is junior consultant and Alpesh Shah, MS, is a fellow at the same institution. They can be reached at Iladevi Cataract and IOL Research Centre, Gurukul Road, Ahmedabad - 380 052, India; (91) 079-7490909 or (91) 079-7492303; fax: (91) 079-7411200; e-mail: shail@ad1.vsnl.net.in.