Changes of Corneal Biomechanical Properties upon Exclusive Ytt-/Sr-90 Irradiation of Pterygium.

Fritz Rigendinger,Zeljka Cvejic,Bojan Pajic,Daniel M Aebersold

doi:10.3390/s21030975

Abstract

Background: It is known that pterygia above a certain size cause astigmatism and other aberrations of the human cornea and thus impair the quality of vision. Exclusive Sr-/Ytt-90 beta irradiation is a highly effective treatment for primary pterygia. The aim of this retrospective study is to determine the extent to which higher order corneal aberrations are affected by this treatment. Methods: Evaluation of corneal topographies and wavefront aberration data of 20 primary pterygia patients generated before and at different points in time in the first year after irradiation. Additionally, the size of the pterygium was measured. Results: The study showed a significant increase in coma and triple leaf aberrations in pterygia with a horizontal length of 2 mm and more. It was also found that a pterygium size greater than 2 mm significantly induces astigmatism. Both phenomena reduce visual quality. In none of the patients could a pterygium recurrence be detected after irradiation. Conclusions: If the pterygium size is less than 2 mm, early exclusive Sr/Ytt-90 beta irradiation can be recommended. If the size is more than 2 mm, a pterygium excision 6 months after beta irradiation can be discussed.

Highlights

A pterygium grows proliferatively toward the center of the cornea with Bowman’s membrane as its guiding structure, which is destroyed [1,2]
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The pterygium appears as an avascular, fibrotic membrane, which is very sharply demarcated from the stromal structure of the cornea

Summary

Introduction

A pterygium grows proliferatively toward the center of the cornea with Bowman’s membrane as its guiding structure, which is destroyed [1,2]. The pterygium appears as an avascular, fibrotic membrane, which is very sharply demarcated from the stromal structure of the cornea. The pterygium can be undermined and is lined with epithelial cells. By means of confocal microscopy, the layers of a pterygium can be visualized very well, from the superficial epithelial cells to the fibrotic structure of the pterygium with epithelial islands at a depth of 80 μm. At a depth of 100 μm, the underminable part is lined with epithelial cells reaching down to the sclera, which begins here at 120 μm (Figure 2). Exclusive Sr-/Ytt-90 beta irradiation is a highly effective treatment for primary pterygia. The aim of this retrospective study is to determine the extent to which higher order corneal aberrations are affected by this treatment

Methods

Findings

Discussion

Conclusion