Laboratory investigationMorphological Study of Corneal Endothelium and Corneal Thickness in Pseudoexfoliation Syndrome
Introduction
The pseudoexfoliation syndrome (PXS) consists of the formation or deposition of white, flake-like material throughout the anterior ocular segments. Pseudoexfoliative materials develop on the lens surface, iris, trabecular meshwork, zonula, and ciliary body.1., 2.
There are many studies of corneal endothelial changes in PXS eyes reporting lower endothelial cell density,3., 4., 5., 6., 7., 8., 9. high coefficient of variation in cell area,3 and a lower percentage of hexagonal cells.3., 4. There are, however, several studies reporting no significant changes in endothelial cell density,10 the coefficient of variation in cell area,4., 5. or the percentage of hexagonal cells5 in PXS eyes. The changes in corneal endothelial morphology in PXS eyes have been controversial.
The PXS syndrome is often found in patients with glaucoma. The central corneal thickness (CCT) of PXS eyes in glaucoma patients was reported to be thinner11 than or similar12., 13. to normal eyes. The endothelial cell density of PXS eyes in glaucoma patients was reported lower than that of PXS eyes in patients without glaucoma6 or in control eyes.7
The aim of this study is to compare the endothelial morphology and central thickness of the cornea between PXS eyes and non-PXS eyes, and PXS eyes in patients with and without glaucoma.
Section snippets
Materials and Methods
We examined 21 patients with PXS (26 corneas;11 corneas in 9 men and 15 corneas in 12 women) at the Nadogaya Hospital between August and November 2001 (the PXS group). Mean patient age was 77.9±6.6 years (mean±SD) (range, 64–90 years). Diagnosis of the syndrome was based on the typical slit-lamp appearance of pseudoexfoliative material at the anterior lens capsule and/or at the pupillary margin. Seven PXS patients (7 eyes) also had glaucoma. Mean patient age was 77.9±4.7 years (range, 70–83
Results
The endothelial cell density was significantly lower in the PXS group (2336±383 cells/mm2) than in the control group (2632±327 cells/mm2) (P = .003) (Figure 1). There was no significant difference between the coefficient of variation in the cell area in the PXS group (0.324±0.033) and that in the control group (0.336±0.041) (P = .21). There was no significant difference between the percentage of hexagonal cells in the PXS group (58.4±8.1%) and that in the control group (58.9±6.6%) (P = .80). The
Discussion
Corneal endothelial changes in PXS eyes are induced by an altered composition and increased flare intensity of the aqueous humor caused by a breakdown of the blood-aqueous barrier.1., 5. By electron microscopy, large clumps of typical pseudoexfoliation material can be found adhering to the corneal endothelium, and masses of pseudoexfoliation material are incorporated into the posterior Descemet membrane.14 These may lead to early corneal endothelial decompensation.1
In the current study, the
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