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Related Experiment Video

Updated: Jul 14, 2026

Anterior High-Resolution Optical Coherence Tomography in the Diagnosis and Therapeutic Monitoring of Ocular Surface Squamous Neoplasia

Anterior High-Resolution Optical Coherence Tomography in the Diagnosis and Therapeutic Monitoring of Ocular Surface Squamous Neoplasia

Published on: August 9, 2024

Ectatic disorders associated with a claw-shaped pattern on corneal topography.

Brandon W Lee¹, Ula V Jurkunas, Mona Harissi-Dagher

¹Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, USA.

American Journal of Ophthalmology

|July 3, 2007

Summary

The claw-shaped pattern on corneal topography is not exclusive to pellucid marginal degeneration (PMD) and can also indicate keratoconus. This finding is crucial for accurate diagnosis of corneal ectatic disorders.

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Published on: October 21, 2022

Area of Science:

Ophthalmology
Corneal Imaging
Refractive Surgery

Background:

Corneal topography is essential for diagnosing and managing corneal irregularities.
Claw-shaped patterns on corneal topography have been historically associated with specific conditions.

Purpose of the Study:

To investigate the clinical findings associated with claw-shaped patterns on corneal topography.
To differentiate between pellucid marginal degeneration (PMD) and other conditions presenting with this topographic feature.

Main Methods:

Retrospective analysis of 3,993 Orbscan II corneal topography records.
Identification and subclassification of 40 eyes with claw-shaped patterns into PMD suspect, keratoconus suspect, and ectasia groups.
Comparison of refractive and topographic indices between PMD suspect and keratoconus suspect groups.

Main Results:

The study identified 40 eyes with claw-shaped patterns, categorized into PMD suspect (9 eyes), keratoconus suspect (27 eyes), and ectasia (4 eyes).
Mean maximal anterior and posterior elevation radii were significantly greater in the PMD suspect group compared to the keratoconus suspect group.
This suggests distinct topographic characteristics despite a similar pattern.

Conclusions:

The claw-shaped pattern on corneal topography is not pathognomonic for pellucid marginal degeneration (PMD).
This pattern is also observed in keratoconus, highlighting the need for careful differential diagnosis.
Corneal topography patterns require comprehensive clinical correlation for accurate diagnosis.