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

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.

Pathological Changes of the Anterior Lens Capsule

The anterior lens capsule (ALC), as the thickest basement membrane in the body, is an acellular, soft, smooth, transparent membrane secreted by lens epithelial cells. The ALC has its unique biomechanical properties to serve as a barrier and separate the lens from infectious viruses and bacteria together with the posterior capsule and pericapsular membrane. However, the biomechanical and ultrastructural properties of the ALC can be changed under certain conditions. Here, we provide a brief review of the pathological changes of the ALC in several eye disorders, including cataract, aniridia, climatic droplet keratopathy, exfoliation syndrome, true exfoliation syndrome, Alport syndrome, and silicone oil tamponade.

Microstructure and Chemical Analysis in Pseudoexfoliation Syndrome

Purpose: The aim of this study is to show the pseudoexfoliation syndrome (PES) material accumulated in the lens anterior capsule and the trace elements directly with using scanning electron microscopy (SEM) and to investigate the effect of PES materials on aqueous humor by chemical analyses.Methods: The study groups consisted of 30 patients with PES and 30 patients without PES. 0.1-0.3 mL of aqueous humor was aspirated from anterior chamber and anterior capsule sample was obtained by applying continuous curvilinear capsulorhexis. The level of selected elements (Zn, Cu, Se, Fe, Si, Al, Ca, K) were determined from aqueous humor samples via Inductively coupled plasma - optical emission spectrometry (ICP-OES) machine. The morphology and elemental distribution of anterior lens capsules were carried out via a Zeiss Sigma 300 scanning electron microscope with energy dispersive X-ray spectroscopy (semiquantitative EDX).Results: For aqueous humor, the ICP-OES results show that Cu and Zn levels is higher (p < .001, both of them) in PES group than that the obtained from control group. It was noticed that the ratio of Cu/Zn was higher (p = .008) in aqueous humor, while Cu/Se ratio was higher in both aqueous humor (p < .001) and anterior capsule (p < .001) for PES group. The SEM images show that different metal precipitates were obtained from anterior lens capsules with PES. However, there is no obvious element precipitates on the anterior lens capsules without PES.Conclusion: The results observed that the level of selected elements can be obtained at different level in both PES group and control group. Especially, if the oxidative behavior of these elements which is thought to play a role in PES formation can be clarified, new approaches will be done to evaluate the structure of PES.

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.

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

BACKGROUND

Exfoliation syndrome (XFS), which is associated with increased surgical complications during phacoemulsification, has a relatively high incidence in Greece. Multiannual surgical experience in XFS patients has led to the clinical observation that hydrodissection occurs more easily in XFS patients.

OBJECTIVE

To compare the ease of hydrodissection between cataract patients with and those without XFS.

METHODS

One hundred and fifteen patients with senile cataract were included in the study. Forty-two of them had XFS. All patients underwent uneventful phacoemulsification by the same surgeon. For hydrodissection, three 1-mL insulin syringes were filled with 0.5 mL balanced salt solution (BSS). Sequentially, each one was quickly and continuously injected underneath the 3, 6, and 9 o'clock positions of the anterior lens capsule. If lens mobilization was achieved with this procedure, hydrodissection was characterized as "easy."

RESULTS

The two groups were matched for age, gender, the biomicroscopic type of cataract, and the presence of diabetes mellitus. Glaucoma occurred more often among the XFS patients (p = 0.002). In 39 of the 42 exfoliation patients (92.8%), "easy" hydrodissection was recorded. In the control group, the corresponding number was 47 out of 73 (64.3%). The two groups differed significantly (p = 0.001).

CONCLUSIONS

Hydrodissection was more easily performed on the XFS patients than on the controls. This finding could be related to the extensive ultrastructural subepithelial alterations of the anterior lens capsule in XFS, as recently described in electron microscopy studies. We suggest that less BSS can be used for hydrodissection in XFS patients during phacoemulsification.

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.

Exfoliation Fibrils within the Basement Membrane of Anterior Lens Capsule: A Transmission Electron Microscopy Study

Purpose: The aim of the present study was to demonstrate novel findings recognized within the basement membrane of the anterior lens capsules (ALCs) in exfoliation syndrome, in a transmission electron microscopy (TEM) study. Materials and methods: Twenty-one patients with age-related cataract were included in the study. Eleven out of them suffered from exfoliation syndrome (XFS). Anterior lens capsules were obtained from patients during phacoemulsification, applying continuous curvilinear capsulorhexis and then were examined by transmission electron microscope. Results: Six out of 11 examined basement membranes with XFS had a granular appearance with dotted deposits of electron-dense material. Fibrils were clearly detected, longitudinally, within the basement membrane, usually located in the outer quarter of the basement membrane, towards the anterior chamber. Conclusion: New data about the exfoliation material and its location within the basement membrane of the anterior lens capsules of XFS patients are presented. These findings constitute new evidence for XFS's histopathogenesis and might help clarify the lenticular exfoliation material's (XFM) mechanisms of origin.