Pellucid Marginal Degeneration (PMD) is a noninflammatory, nonhereditary cause of corneal ectasia with bilateral, clear, inferior (typically 4 o’clock to 8 o’clock), peripheral corneal thinning.

Apr 15, 2005 · It demonstrates that keratoconus is a mid-peripheral thinning disorder, while PMD is a peripheral thinning disorder. To determine the peak elevation index, place the cursor over the highest elevation point on the topographers elevation map.

Forty-seven eyes of 32 patients with crab claw patterns were identified from 2751 patients with corneal ectasia. They were divided into two groups, inferior keratoconus and PMD, based on clinical findings. The topographic, tomographic, and densitometric measurements were analyzed.

Aug 1, 2019 · Clinicians need to dig a little deeper when they see a topography map that shows a “crab claw” pattern. The term pellucid marginal corneal degeneration (PMD) is widely used in the ophthalmic profession to describe a characteristic topographic appearance.

Pellucid marginal degeneration (PMD) is a degenerative corneal condition, often confused with keratoconus. It typically presents with painless vision loss affecting both eyes. Rarely, it may cause acute vision loss with severe pain due to perforation of the cornea.

Aug 15, 2022 · PMD is the same thing as keratoconus, just a subclass of it. If your doctor told you that you have PMD, you likely get decent vision with updated eyeglasses and received diagnosis later in life compared to others with keratoconus.

May 1, 2019 · “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,” the researchers wrote in their ARVO abstract.

Nov 14, 2023 · Pellucid marginal degeneration (PMD) is an uncommon, progressive, non-inflammatory corneal ectatic disorder with thinning of the inferior cornea in a crescent-shaped pattern. 1 The corneal ectatic transformation occurs concentric with the inferior limbus and is separated from it by a distance of 1–3 mm. 2 Tissue loss and crescentic stromal ...

Mar 9, 2021 · Corneal topography is the main diagnostic tool of PMD with characteristic diagnostic patterns "crab-claw" or "butterfly." PMD could be mistaken as KCN, keratoglobus, and other peripheral...

They evaluated corneal elevation and thickness in pa-tients with PMD and keratoconus using the Orbscan corneal topography system (Bausch & Lomb), generat-ing the PMD index, which displays a high sensitivity and specificity in diagnosing PMD.