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Posterior Embryotoxon Revisited: An Immunohistologic Study.
Saeed Alwadani1, Wallace L M Alward2, Nasreen A Syed3
1King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia; Department of Ophthalmology, King Saud University School of Medicine, Riyadh, Saudi Arabia.
Ophthalmology. Glaucoma
|February 8, 2022
Summary
Posterior embryotoxon (PE) is a peripheral corneal stromal nub, not a displaced Schwalbe line. Histopathology reveals variable locations and an abnormal extracellular matrix, challenging current definitions.
Area of Science:
- Ophthalmology
- Histopathology
- Corneal Anatomy
Background:
- Posterior embryotoxon (PE) is often misidentified as an anteriorly displaced Schwalbe line.
- Understanding the true nature of PE is crucial for accurate diagnosis and management.
Purpose of the Study:
- To elucidate the immunopathologic features of posterior embryotoxon (PE).
- To determine the precise anatomical location and extracellular matrix composition of PE.
Main Methods:
- Analysis of archived formalin-fixed, paraffin-embedded corneal specimens from 9 patients with PE.
- Light microscopy and immunohistochemistry to characterize the extracellular matrix of PE.
Main Results:
- PE presents as peripheral corneal stromal nubs, not a displaced Schwalbe line.
- Locations of PE were variable, including anterior to, posterior to, or at Schwalbe line.
- Immunohistochemistry showed PE's extracellular matrix is similar to corneal stroma but with some staining variations.
Conclusions:
- Histologic findings redefine PE as a corneal stromal extension, not a displaced Schwalbe line.
- PE's variable location can displace Descemet membrane.
- The extracellular matrix of PE shares similarities with corneal stroma, with distinct staining patterns.
