Human senile cataract. Light- and electron-microscopic studies of the morphology of the anterior lens structures, with special reference of anterior capsular/subcapsular opacity

Detecting Apoptotic Human Lens Epithelial Cells With Transmission Electron Microscopy

Introduction Cataract formation is a prevalent issue worldwide, and understanding the cellular processes involved is crucial to advancing treatment options. The scope of the study was to explore the presence of apoptotic cells in the lens epithelium of Greek patients with senile cataracts using transmission electron microscopy (TEM). Methods Twenty-one patients with senile cataracts were included in this cross-sectional study, and their anterior lens capsules were thoroughly examined. The presence of apoptosis was ultrastructurally investigated, and its association with age, gender, biomicroscopic type of cataract, the coexistence of exfoliation syndrome (XFS), diabetes mellitus, and glaucoma was statistically correlated. Results We detected apoptotic cells in nine of the 21 patients. Morphological features indicative of apoptosis in the nuclei included degradation, nuclear membrane irregularity, reduction of nuclear volume, condensation, and margination of chromatin. The cytoplasm either appeared denser or contained vacuoles. Budding with membrane blebbing and pinopode-like projections were frequently observed. Apoptotic cells appeared smaller, exhibiting loose connections with neighboring cells and the basement membrane (BM). Interestingly, apoptotic bodies were also detected. Conclusions None of the examined risk factors showed a connection to apoptosis, whereas neighboring lens epithelial cells (LECs) phagocytose apoptotic bodies, seemingly assumed the role of macrophages. Comparing apoptosis rates between populations with different sun exposure levels could help reveal the relationship between ultraviolet B radiation exposure, apoptosis, and cataract formation.

Structural Characteristics of the Lens in Presenile Cataract

The purpose of this work is to examine the structure of the anterior lens epithelial cells (aLECs) of presenile idiopathic cortical cataract to investigate the possible structural reasons for its development. The anterior lens capsules (aLCs: basement membrane and associated lens epithelial cells) were obtained from routine uneventful cataract surgery of 5 presenile cataract patients (16 and 41 years old women and 29, 39, and 45 years old men). None of the patients had family history of cataract, medication, or trauma and they were otherwise healthy. In addition, the patients did not have any other abnormal features in the ocular status except cataract. The aLCs were prepared for scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The most prominent abnormal features observed by SEM for all 5 studied presenile cataract patients were the changes of the aLECs structure with the dents, the selective concavity of some LECs, at their apical side centrally toward the nucleus. In addition, TEM showed the thinning of the lens epithelium with the segmentally concave cells and the compressed and elongated nuclei. Abnormal and distinguishable structural features were observed in the anterior lens epithelium aLECs in all 5 patients with presenile cataract. Disturbed structure of aLECs, regularly present in presenile cataract type is shown that might be associated with water accumulation in the presenile idiopathic cortical cataract lens.

Pseudoexfoliation syndrome in diabetic patients: transmission electron microscopy study of anterior lens epithelial cells

Purpose: to examine the lens epithelial cells in diabetic patients with pseudoexfoliation to ultramicroscope and to compare the findings with those of patients without diabetes mellitus (DM) and/or without pseudoexfoliation (PEX).

Materials and Methods: Forty patients aged 65-86 years were enrolled in the study. All patients had senile cataract and were divided into four groups of ten patients in each group. Group I: patients without pseudoexfoliation, without DM, Group II: without pseudoexfoliation, with DM, Group III: with pseudoexfoliation, without DM, Group IV (Pseudoexfoliation-Diabetic Group): with pseudoexfoliation, with DM. In all cases, part of the central portion of anterior lens capsule was removed during routine cataract surgery, and was properly prepared in order to be examined under a transmission electron microscope.

Results: In the control group, mainly degenerative alterations to varying extents were observed. In all groups, intracellular and extracellular oedema, multilayering, apoptosis, completely destroyed cells adjacent to normal cellswere described. In the diabetic group, alterations were more severe with respect to group I. In PEX cases, the additionalirregularity of the epithelium surface, loose intercellular connection, as well as the loose connection between cells and basement membrane were described with the presence of PEX material free and within the basement membrane. In cases with PEX and DM, degenerative alterations and PEX material were observed as well, but the epithelium was better conserved compared to the PEX group.

Conclusion: the observed lesions were more extended and more frequent in the pseudoexfoliation group, followed by the diabetic group. The pseudoexfoliation-diabetic group presented less intense modifications raising questions about the interaction of these different diseases.

Abbreviations: DM = Diabetes Mellitus, PEX = Pseudoexfoliation, PXM = Pseudoexfoliative Material, AD = Alzheimer disease, TGF-β1 = Transforming Growth Factor beta 1, WHO = World Health Organization, LEC = Lens Epithelium Cells, BM = Basement Membrane, CM = Cytoplasmic Membrane

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

BACKGROUND

Hydrodissection was recently reported to occur more easily in patients with exfoliation syndrome (XFS). Transmission electron microscopy (TEM) studies have already revealed alterations of the lens epithelial cells (LECs) and their apical membrane towards the lens fibers.

OBJECTIVE

The aim of this work was to examine the three-dimensional appearance of the lens epithelium in patients with XFS.

METHODS

Fourteen patients with senile cataract, 7 of whom had XFS, were included. Anterior lens capsules (aLCs) were obtained with continuous curvilinear capsulorrhexis (CCC) during phacoemulsification and were examined with scanning electron microscopy (SEM) and TEM.

RESULTS

Exfoliation samples exhibited an overall more irregular apical surface of the lens epithelium compared to control aLCs. The height of LECs varied extensively. On the apical surface of LECs, amorphous, crystalline-like, or microgranular extracellular material and membranous, oval-shaped structures were documented with SEM. All findings were connected to corresponding observations with TEM and were not correlated to the type of cataract.

CONCLUSIONS

In XFS patients, the lens epithelial surface exhibited a highly irregular margin, with extracellular material covering the apical membrane of LECs. We suggest that XFS probably causes both epithelial and lens fiber degeneration which, during CCC and mechanical extraction of the aLC from the lens cortex, result in diverse alterations.

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

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.

Transmission electron microscopy study of undescribed material at the anterior lens capsule in exfoliation syndrome

PURPOSE

In the present study, we aimed to examine the anterior lens capsule using transmission electron microscopy (TEM) and compare the findings in patients with and without exfoliation syndrome (XFS).

METHODS

Eighteen patients with senile cataract, including 10 with XFS, were included. Anterior capsule specimens were obtained from patients during phacoemulsification through continuous curvilinear capsulorrhexis, and were examined via TEM.

RESULTS

In the XFS group, in addition to the typical fibrillar material above the basement membrane of the lens capsule, another unknown, microgranular, electron-dense, unbound material was observed beneath the lens epithelium. Larger formations appeared to detach from the surface of the epithelial cells, and oval or crescent-shaped structures of an electron-denser material were less commonly observed on the apical side of the epithelium. Membranous structures were occasionally attached to epithelial cells that often exhibited thicker or ruptured cell membranes on their apical-free side, along with deposits of electron-dense material. Degenerative lesions of various severities were observed at the epithelium in both groups.

CONCLUSION

The anterior lens capsule epithelium in patients with XFS exhibits a highly irregular and rough margin on its free side, with unbound material over its membrane, which probably contributes to loose contact with the underlying lens and leads to different clinical behaviors in XFS eyes during cataract surgery.

Ultrastructure of anterior lens capsule of intumescent white cataract

PURPOSE

To analyse the anterior lens capsule thickness and ultrastructure changes of intumescent white cataracts in comparison with nuclear cataracts to prove possible structural reasons for surgical difficulties with the intumescent white cataract.

METHODS

Anterior lens capsules from 35 eyes with intumescent white and 35 eyes with nuclear cataracts were analysed for their thickness by semithin sections technique and for morphological characteristics by transmission electron microscopy.

RESULTS

Capsule thickness was not significantly different in intumescent white compared to nuclear cataracts (mean values 17.5 and 18.5 μm, respectively, p = 0.369). The main morphological features of capsules were extrusions of capsule at the basement membrane-epithelial border embedding cellular material which were significantly more frequent in intumescent cataracts. Filaments in the basement membrane as well as rarefication of its structure and lamellae were often concomitant with the extrusions.

CONCLUSIONS

Anterior capsules of white intumescent cataracts do not differ in thickness but have different ultrastructure morphology compared to nuclear cataracts. The extrusions of basement membrane at the basement membrane-epithelial border towards epithelium, the filamentary inclusions within basement membrane and its rarefication could be the structural causes of tensile weakness and hence additional reason to surgical problems.

Lens capsule and epithelium in age-related cataract

On the basis of preoperative assessment of patient characteristics, intraoperative obtainment of a lens-capsule and epithelium specimen, histopathologic investigation of lens capsule and epithelium, and biochemical analysis of glutathione reductase in lens epithelium, age-related cataract was studied in 50 adult patients who underwent consecutive extracapsular cataract-posterior chamber lens implant surgery. Patients (25 men and 25 women; age range, 41 to 91 years; mean age, 75 years) had a wide range of systemic and ocular disease; 17 of 50 (34%) patients had a history of severe vision-impairing cataract in a first-degree relative. Anterior lens-capsule thickness ranged from 10 to 22 microns, with a mean of 17 microns. Statistical analysis of lens-epithelium ultrastructure in 41 of 50 specimens documented mixing of normal and abnormal cells, verified a gradation in the degree of abnormal ultrastructural features, and demonstrated a statistically significant decrease in epithelial cytologic activity with advancing age (P = .038). Biochemical analysis documented a severe glutathione reductase deficiency in nine of 39 (23%) lens-epithelium specimens, possibly reflecting a dietary deficiency of riboflavin.

The effect of calcium on the lens ultrastructure

The influence of a calcium-enriched solution on pig lens cell structure was studied in vitro. The morphological changes which occurred 20 min or 2 h after bathing in the solution were studied by transmission electron microscopy. After 20-min incubation, small intercellular vacuoles containing membranous and amorphous substance occurred mainly in the epithelial cells. The cytoplasm of the cortical fibers had already been dissolved at this stage. Here the membrane was disrupted and the extracellular spaces widened. After 2-h incubation, the epithelial cells were compressed by adjacent swollen fibers. However, vacuolization in the epithelium had decreased at this stage. At the cortical fiber zone, vacuolar formation had increased extensively. Vacuolization was mainly observed in the intercellular spaces between the intact gap junctions. After 2 h, the main alterations were membrane disruptions and advancing dissolution of the cytoplasm. Deeper cortical fibers were swollen but showed no extracellular vacuoles.

Cataract in retinitis pigmentosa. An analysis of cataract surgery results and pathological lens changes

The result of cataract surgery and lens pathoanatomical examination were presented in patients with retinitis pigmentosa (RP). A retrospective study of 24 cataract extractions in 15 RP patients was carried out, with special regard to visual outcome and surgical complications. The results were compared to an age matched randomly selected control group. In the retinitis pigmentosa group the post-operative visual acuity was generally good, and the surgical complications except for one case of central venous thrombosis were not more frequent than in the control group. Seven lenses from 5 patients with RP were analysed using transmission electron microscopy and quantitative microradiography. In the lenses with a progressive subcapsular edema, extensive extracellular vacuolization was found in the lens epithelium. Focal degeneration of epithelial cells was seen both in the more stationary posterior subcapsular cataracts and the progressive subcapsular cataracts. Different degrees of mitochondrial swelling was found in the epithelial cells of the stationary cataracts. The subcapsular lens fiber changes consisted of an extensive swelling of hydrated cells together with a significant reduction in their dry mass content. Migrating elongated nuclei-containing cells were found on the posterior capsule in both stationary and progressive cataracts.

Acid phosphatase localization in the equatorial region of human lenses

Localization of acid phosphatase activity is described in equatorial segments of four human cataractous lenses, including one lens with equatorial cortical cataract, and three lenses with no significant equatorial opacities. The lenses were removed surgically with a cryoprobe. Enzyme reaction product was confined mostly to epithelial and cortical Golgi complexes and dense bodies, and to cortical smooth endoplasmic reticulum (SER). It also was located in small cortical vacuolar cysts in the lens with equatorial cataract, and intercellularly in a single lens which was devoid of equatorial opacity. In the latter case, intercellular activity was confined mostly to areas showing minimal pathological modification. Evidence is presented that the cortical SER represented GERL. The hypothesis is made that intercellular acid hydrolase activity might play a role in the early stages of human senile cortical cataract development. However, it is recognized that confirmation of this hypothesis will require additional studies involving comparison of both cataractous and normal lenses of various ages, which have been removed by a careful procedure which minimizes the lysis of lens cells.