Posters

New “Quad Signs“ in diagnosing pellucid marginal degeneration

Poster Details

First Author: M.Jafarinasab IRAN

Co Author(s): S. Safi   M. Babaei                 

Abstract Details

Purpose:

The diagnosis of pellucid marginal degeneration (PMD) and its differentiating from keratoconus (KCN) is a challenging issue in corneal ectasia. PMD can be distinguished from KCN through clinical examination and corneal imaging in advanced cases; however it is not easy in early stages of PMD. This study was designed to introduce new topographic criteria for diagnosing and grading the severity of PMD.

Setting:

Epidemiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran (the Islamic Republic of);.Department of Ophthalmology, Labbafinejad Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran (the Islamic Republic of);

Methods:

In this cross-sectional study, topographic patterns of patients referred to the Cornea and Refractive Surgery Services at Labbafinejad Medical Center or a private clinic were reviewed and diagnosed as early, subclinical or clinical KCN or PMD.

Results:

Topographic patterns and parameters of 120 subjects were evaluated. Analysis of indices provided 4 diagnostic signs to characterize all stages of PMD including subclinical disease. These parameters included (A) Inferior  flattening island (IFI) inferior to the horizontal axis (B) an apple shaped pattern formed by mean power area as a yellow strip (C) superior flattest area (SFA),the flattest area at the superior quadrant (D) against the rule irregular astigmatism (flat meridians @45-135 degrees) . In addition, measuring the extent of IFI could be helpful for staging PMD and could be considered as a characteristic sign of early PMD.

Conclusions:

Four main topographic signs including inferior flattening island, apple shaped pattern, superior flattest area and against the rules astigmatisms can be considered as diagnostic signs for PMD.

Financial Disclosure:

None