Severe Abnormalities of Lens Epithelial Cells in Exfoliation Syndrome: A Transmission Electron Microscopy Study of Patients with Age-Related Cataract

Abstract

Background and objectives: The aim of this study was to examine via electron microscopy the lens epithelial cells in age-related cataracts and compare the findings between patients with and without exfoliation syndrome, in the Greek population. Materials and Methods: Twenty-one patients with age-related cataracts, older than 60 years, were included in the study. Eleven of them also suffered from exfoliation syndrome. Anterior lens capsules, obtained during phacoemulsification, were examined with a transmission electron microscope. Results: In all cases, ultrastructural features of diffuse intracellular and extracellular oedema were noticed to a varying degree and transparent vacuoles were detected. Often, there was more than one layer of cells, giving the impression that healthier cells tried to cover neighboring cells presenting extensive damage. Commonly, cells lost their regular shape and appeared with expanded nuclei carrying dense granules. Apoptotic cells were also detected. The epithelial cells frequently were completely destroyed or absent, exhibiting loose connections amongst them or with the basement membrane. In exfoliation syndrome (XFS) patients the alterations were more severe. Additionally, the lens epithelial cells (LECs) apical cell membrane appeared with varying distances from the basement membrane, due to different cell “heights”, creating an irregular margin of the epithelium (p < 0.05). Conclusion: Transmission electron microscope (TEM) examination revealed ultrastructural abnormalities in all patients’ lens epithelia, more extended and more frequently observed in XFS group. In all cases, the lesions were comparable to those described in severe pathologies, all of which were excluded from the study. Environmental factors such as increased ultraviolet B (UVB) radiation exposure in Mediterranean countries, genetic factors, epigenetic factors, or all of them, could contribute to these alterations. Further epidemiological and molecular biology research is needed, so as to justify these results.

Lens Epithelial Surface Disorders in Exfoliation Syndrome: A Scanning and Transmission Electron Microscopy Study

“…TEM examination revealed similar findings to our previous studies [14, 16]. An unbound, electron-dense, microgranular, spherical material was recorded in 3 out of 7 XFS aLCs (Fig.…”

“…We recently studied aLCs of XFS patients with transmission electron microscopy (TEM) for the first time in a Greek population. We have already reported novel TEM observations such as severe abnormalities of the lens epithelial cells (LECs) [14], the presence of exfoliation fibrils within the basement membrane of the aLC [15], and the presence of a new, not previously described material on the apical side of the lens epithelium, towards the lens fibers [16]. It is mainly the latter ultrastructural alterations that seem to be related to easier hydrodissection in XFS patients, as described lately [17].…”

Ease of Hydrodissection during Phacoemulsification: A Comparison between Patients with and Those without Exfoliation Syndrome

“…It was this observation that stimulated our recent transmission electron microscopy studies of anterior lens capsules in XFS. Transmission electron microscopic examination revealed severe abnormalities of lens epithelial cells [13], the presence of exfoliation fibrils within the basement membrane of the anterior lens capsule [18], and the presence of new, not previously described material on the apical side of the lens epithelium towards the lens fibers [12]. The lens epithelial surface exhibited a highly irregular margin, with extracellular material covering the lens epithelial cells' apical membrane in exfoliation patients.…”

“…Recent electron microscopy studies of the anterior lens capsule in patients with XFS have revealed newly described ultrastructural alterations of the lens epithelium and its apical surface towards the lens fibers, indicating a disorder of the lens's epithelial-fiber interface in XFS [12,13]. To our knowledge, there has been no report or any kind of evaluation of difficulties with hydrodissection among patients with cataract, including those with XFS.…”

Spontaneous Lens Rupture in Congenital Cataract, Presented as Lens Fragment Within the Anterior Chamber

“…In electron microscopy observation, the LECs’ flattening seems to be related to cataract degenerative manifestations, which constitute a quite common finding [ 6 ]. However, LECs’ destruction is not usually described ultrastructurally and, in this case, is probably attributed to the mechanical friction caused by lens rupture.…”