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Onion Peel!

Posterior polar cataract is a rare form of congenital cataract which has either an autosomal dominant inheritance or can be sporadic

Persistence of hyaloid artery or invasion of lens by mesoblastic tissue- forms during embryonic life and is symptomatic three to five decades later

Dysplastic abnormal lens fibres that migrate posteriorly from the equator and cause an opacity in the central region of the posterior capsule

Specific Symptoms:

Increasing glare

Difficulty in reading fine prints

These are due to Forward Light Scattering (light scattering towards the retina)


Stationary- Central opacity with bull’s eye ring appearance (or onion peel appearance)

Progressive- Central opacity with enlarging radiations over time

Singh Classification Types:

1 Opacity associated with posterior subcapsular cataract

2: Opacity with ringed onion like appearance

3: Opacity with dense white spots at the edge often associated with thin or absence of the posterior capsule

4: Combination of 1,2, or 3 with nuclear sclerosis

The dense white spots are a diagnostic sign - Daljit Singh Sign

Schroeder Grades:

I: Small opacity without any effect on the optical quality of the lens

II: A 2/3rds obstruction of red reflex

III: Disc like opacity in the posterior capsule surrounded by an area of further optical distortion. Only dilated pupil shows a clear red reflex surrounding the zone

IV: Opacity is totally occlusive - no sufficient red reflex is obtained by pupillary dilatation

Why is it important to diagnose this cataract?

The abnormal lens fibers can become strongly adherent to the central posterior capsule, and the capsule around the plaque is often thin and weakened or sometimes even absent - High rate of intraoperative posterior capsular rupture during cataract surgery and necessary precautions should be taken to avoid this complication (more on this later)

Image from Rajan Eye Care Hospital #ophthalmology #ophthal #cataract #posteriorpolarcataract #ppc

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