Ultrastructure of anterior lens capsule of intumescent white cataract

Human Primary Lens Epithelial Cultures on Basal Laminas Studied by Synchrotron-Based FTIR Microspectroscopy for Understanding Posterior Capsular Opacification

Human primary lens epithelial cultures serve as an in vitro model for posterior capsular opacification (PCO) formation. PCO occurs when residual lens epithelial cells (LECs) migrate and proliferate after cataract surgery, differentiating into fibroblastic and lens fiber-like cells. This study aims to show and compare the bio-macromolecular profiles of primary LEC cultures and postoperative lens epithelia LECs on basal laminas (bls), while also analyzing bls and cultured LECs separately. Using synchrotron radiation-based Fourier transform infrared (SR-FTIR) (Bruker, Karlsruhe, Germany) microspectroscopy at the Spanish synchrotron light source ALBA, we observed that the SR-FTIR measurements were predominantly influenced by the strong collagen absorbance of the bls. Cultured LECs on bls showed a higher collagen contribution, indicated by higher vas CH3, CH2 and CH3 wagging and deformation, and the C-N stretching of collagen. In contrast, postoperative LECs on bls showed a higher cell contribution, indicated by the vsym CH2 peak and the ratio between vas CH2 and vas CH3 peaks. The primary difference revealed using SR-FTIR is the greater LEC contribution in spectra recorded from postoperative lens epithelia compared to cultured LECs on bls. IR spectra for bl, cultured LECs and postoperative lens epithelia could be valuable for future research.

[Optimization of phacoemulsification technique for Morgagnian cataract]

PURPOSE

This study was conducted to develop a new optimized phacoemulsification technique for Morgagnian cataract taking into account the anatomical and topographic parameters of the lens nucleus.

MATERIAL AND METHODS

A working classification of Morgagnian cataract was developed based on the size of the nucleus: if the edge of the nucleus is visualized at the upper edge of the pupil or between the upper edge and the middle of the pupil, it was classified as an initial stage of Morgagnian cataract with a large nucleus; if the upper edge of the nucleus is visualized in the middle of the pupil and below, it was classified as an advanced stage of Morgagnian cataract with a small nucleus. The first group included six patients who underwent surgery using the scaffold technique with removal of the whole small nucleus into the anterior chamber. The second group included 11 patients who underwent surgery using the scaffold technique with removal of the last fragment of the nucleus into the anterior chamber.

RESULTS

The use of the scaffold technique with removal of the nucleus into the anterior chamber helped reduce the number of intraoperative complications to 16.7% in the first group, compared to 27.3% in the second group, and the percentage of endothelial cell loss to 10.1% in the first group, compared to 10.7% in the second group.

CONCLUSIONS

The anatomical and topographic features of the lens and the anterior segment of the eye in Morgagnian cataract with a small nucleus allow for preliminary implantation of an intraocular lens into the capsular bag to protect the posterior capsule during phacoemulsification of the nucleus with minimal mechanical, hydrodynamic and acoustic damage to the surrounding structures of the eye.

Age-related appearance of lamellar structures in lens capsule of cataractous eyes and its pathological significance

PURPOSE

To determine morphological changes in the lens capsule with aging.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

DESIGN

Cross-sectional study.

METHODS

25 eyes from the older patient group (aged 80 years or older) and 25 eyes from the younger patient group (aged 65 years or younger) who were diagnosed with cataract and indicated for surgery were included in the study. After continuous curvilinear capsulorhexis, the anterior lens capsule was collected, immediately fixed, and processed for electron microscopy analysis. Backscattered electron images of the cross-section of the anterior lens capsule were observed under a scanning electron microscope. The ultrastructure of the anterior lens capsule was observed and compared between the groups. Factors associated with the occurrence of the lamellar structure were also identified, with the presence or absence of a lamellar structure as an objective variable and preoperative clinical characteristics as the explanatory variables.

RESULTS

50 eyes of 50 patients were included. In the younger patient group, 20 eyes (80%) had a homogeneous lens capsule, whereas 5 eyes had lamellar structures. By contrast, in the older patient group, 5 eyes had homogeneous structures, while the remaining 20 eyes (80%) had lamellar structures. 1 eye showed capsular delamination. The only significant factor for the occurrence of lamellar structures was age group ( P < .01, nominal logistic regression analysis).

CONCLUSIONS

Lamellar structures appear in the anterior capsule during aging. The appearance of lamellar structures indicates fragility of the lens capsule, which may, in turn, lead to capsular delamination or lens dislocation in some cases.

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.

Ultrastructural Analysis of the Anterior Lens Epithelium in Cataracts Associated with Uveitis

PURPOSE

To investigate the transmission electron microscopic findings of lens epithelial cells (LECs) in patients with different subtypes of uveitis and to compare the findings with those in age-matched controls.

METHODS

In this prospective case-control study, the anterior lens capsules were taken from 47 eyes of 47 patients with uveitis of different subtypes (17 with Fuchs uveitis syndrome [FUS], 13 with -Behçet's uveitis, 10 with idiopathic uveitis, and 7 with herpetic keratouveitis) and from 15 eyes of 15 control patients.

RESULTS

In the FUS group, the LECs had homogeneous thickening and irregularity, with some small vacuoles and widespread, oval-shaped pigment clusters in some areas. In the Behçet uveitis group, there was evident thinning in the lens epithelium. The subepithelial tissue under the epithelium was thickened, and edematous areas were detected. In the idiopathic uveitis group, the LECs were thinner with small vacuoles, and the cubic structure of the LECs was transformed into a squamous one. Moreover, the LECs included some small vacuoles, similar to those in the FUS group. In the herpetic keratouveitis group, two prominent cell types were observed: (1) completely normal LECs and (2) degenerated-type LECs with pyknotic nuclei, condensation of chromatin, swelling in the cytoplasm, membrane ruptures, and intra-cytoplasmic inclusion bodies. In the control group, the LECs and all of their elements occurred in normal ultrastructural patterns, with the exception of a few small intraepithelial vacuoles, which were fewer in number and smaller than those in the FUS and idiopathic uveitis groups.

CONCLUSION

The electron microscopic analysis of LECs of patients with different subtypes of uveitis revealed significant ultrastructural alterations, which may be related to the summation of oxidative stress and intraocular inflammation.

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.

[Ultrasound biomicroscopy for examination of the anterior segment of the eye in patients with intumescent cataract]

According to a prospective review study by H. Gimbel, A. Willerscheidt (1993), among 2967 cataract cases analyzed in 1991, mature intumescent cataract was observed in 34 (1.15%) patients.

PURPOSE

To determine the parameters of the ocular anterior segment in patients with intumescent cataract and in their fellow eyes using ultrasound biomicroscopy (UBM) for identification of differential characteristics of intumescent cataract.

MATERIAL AND METHODS

The results of preoperative diagnostic examination of the anterior segment of the eye with UBM of 21 patients (21 eyes) with intumescent cataract and their 21 fellow eyes (42 eyes in total) were analyzed.

RESULTS

The mean anterior chamber depth according to UBM was 1.96±0.108 mm (from corneal endothelium), in the fellow eyes - 2.74±0.11 mm. The anterior chamber angle was 11.54±2.19°, in the fellow eyes - 20.63±4.08°. The lens thickness in the eyes with intumescent cataract was 5.26±0.13 mm, in the fellow eyes - 4.34±0.09 mm. The length of Zinn ligaments in the external, interior and superior ocular segments of the main group eyes were equal, in the inferior segments they were longer by 0.1 mm. The difference in Zinn ligament length in the eyes with intumescent cataract and fellow eyes was approximately 0.1-0.15 mm in all segments. The equatorial angle in the eyes with intumescent cataract was 32.52±0.92°, in the fellow eyes - 14.85±1.09°.

CONCLUSION

A differential symptom of intumescent cataract was identified - complete spherophakia, as confirmed by a specific UBM sign: increase of the equatorial angle by 17° in comparison with the fellow eye, while the length of Zinn ligament remains equal in all segments.

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.

[Determination of intralenticular pressure in patients with intumescent cataract]

When the lens swells, a liquefied lenticular substance that increases intralenticular pressure accumulates in the lens bag making it difficult to perform standard capsulorhexis. Thus, determination of the intralenticular pressure value is of great importance for safe intumescent cataract phacoemulsification.

PURPOSE

To develop a technology for intralenticular pressure measurement in patients with intumescent cataract and to construct a mathematical model for its prognosis according to preoperative examination data.

MATERIAL AND METHODS

Intralenticular pressure was measured in 11 eyes with intumescent cataract. Before that, the following parameters of the anterior compartment of the eye were examined: anterior chamber depth, lens thickness according to ultrasound biomicroscopy (UBM), hypoechogenic layer (the anterior layer of liquefied lenticular masses), equatorial angle.

RESULTS

The intraoperative technology of the intralenticular pressure measurement was developed. The direct dependency between thickness of the swelling lens, hypoechogenic layer value (the anterior layer of liquefied lenticular masses), anterior chamber depth and intralenticular pressure magnitude was defined.

CONCLUSION

For the first time, the intraoperative intralenticular pressure was measured in patients with intumescent cataract. A dependency was defined between the thickness of the lens and the anterior layer of liquefied lenticular masses, anterior chamber depth, and intralenticular pressure magnitude; based on this, a mathematical model for intralenticular pressure measurement was constructed.

[Intumescent cataract surgery]

Intumescent cataract surgery is one of the topical problems of ophthalmology. The article reviews methods of intumescent cataract diagnostics and structural features of swelling lens. Manual or femtolaser-assisted anterior continuous circular capsulorhexis and intumescent cataract phacoemulsification techniques require further research.

Anterior lens capsule and epithelium thickness measurements using spectral-domain optical coherence tomography

Background

To investigate the anterior lens capsule and epithelium thickness (defined as anterior lens capsular complex: ALCC) in normal Chinese subjects using spectral-domian optical coherence tomography (SD-OCT) and examine the factors that may influence the ALCC, such as age, gender, pupil diameter (PD) and signal strength index (SSI).

Methods

A prospective observational case series. One-hundred-thirty-four normal subjects (134 eyes) were included. The ALCCs were determined manually via SD-OCT. Using the pupil center as a reference position, the central ALCC (CALCC), nasal 1-mm ALCC (NALCC), temporal 1-mm ALCC (TALCC) and PD were measured manually.

Results

The mean CALCC, NALCC and TALCC were 33 ± 6 μm, 36 ± 7 μm and 34 ± 6 μm, respectively. The NALCC was significantly thicker than the CALCC (P < .001) and TALCC (P < .001). Moreover, CALCC was significantly thinner than TALCC (P = 0.013). Age was positively correlated with the CALCC (r = 0.292, P < .001), NALCC (r = 0.400, P < .001) and TALCC (r = 0.521, P < .001). PD, gender and SSI were not significantly correlated with the three ALCC parameters.

Conclusions

The SD-OCT can be used to demonstrate the ALCC thickness, and age is positively correlated with the ALCC in the central, nasal and temporal sides.

Anterior lens epithelium in cataract patients with retinitis pigmentosa - scanning and transmission electron microscopy study

PURPOSE

In retinitis pigmentosa (RP) patients, relatively minor lens opacity in central part of posterior pole of the lens may cause disproportionate functional symptoms requiring cataract operation. To investigate the possible structural reasons for this opacity development, we studied the structure of the lens epithelium of patients with RP.

METHODS

The anterior lens capsule (aLC: basement membrane and associated lens epithelial cells, LECs) was obtained from cataract surgery and prepared for scanning and transmission electron microscopy (SEM and TEM).

RESULTS

Both SEM and TEM show a number of abnormal features in the anterior lens epithelium of cataract patients with RP. The abnormalities appear mainly as holes, thinning and degradation of the epithelium, with the dimensions from <1 μm to more than 50 μm. Other types of holes in size up to 20 μm were seen that may be formed by gradual stretching of the lens epithelium. Another type of abnormalities was cracks that were seen between adjacent LECs, with dimensions 0.1-2 μm × up to 10 μm.

CONCLUSIONS

Abnormal structural features were observed in the anterior lens epithelium that may cause water influx into the lens. This may lead to clouding along the water clefts leading towards the posterior pole in the RP cataractous lens. We suggest that the lens epithelium has a role in the development of the cataract in patients with RP.

Anterior lens epithelial cells attachment to the basal lamina

PURPOSE

To study the structure of the anterior lens epithelial cells (aLECs) and the contacts of the aLECs with the basal lamina (BL) in order to understand their role in the lens epithelium's function.

METHODS

The aLCs (BL and associated aLECs) were obtained from routine uneventful cataract surgery, prepared for and studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and confocal microscopy.

RESULTS

SEM shows that the basal surface of the aLECs (~10-15 μm) is with aLECs foldings (~1-3 μm) and extensions (~0.5-3 μm) attached to the BL. Confocal microscopy images of the basal sections of the aLECs after membrane staining also suggest that the basal part of aLECs has foldings (~1-3 μm). TEM shows in the aLECs basal parts, towards BL, the structures that look like entanglement (~1-4 μm). In cases where there is a swelling of the cytoplasm and offset of the aLECs from the BL, individual extensions (~0.5-2 μm) that extend to the BL are visible by TEM.

CONCLUSIONS

We provide detail evidence about the structural organization of the aLECs, in particular about their basal side which is in contact with the BL. This is supported by the complementary use of three techniques, SEM, TEM and confocal microscopy, each of them showing the same morphological features, the extensions and the entanglements of the aLECs cytoplasmic membrane at the border with the BL. The basal surface of the aLECs is increased. It suggests the functional importance of the contact between aLECs and BL.

Anterior lens epithelium in intumescent white cataracts - scanning and transmission electron microscopy study

PURPOSE

Our purpose was to study the structure of the lens epithelial cells (LECs) of intumescent white cataracts (IC) in comparison with nuclear cataracts (NC) in order to investigate possible structural reasons for development of IC.

METHODS

The anterior lens capsule (aLC: basement membrane and associated LECs) were obtained from cataract surgery and prepared for scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

RESULTS

We observed by SEM that in IC, LEC swelling was pronounced with the clefts surrounding the groups of LECs. Another structural feature was spherical formations, that were observed on the apical side of LEC's, towards the fibre cell layer, both by SEM and TEM. Development of these structures, bulging out from the apical cell membrane of the LEC's and disrupting it, could be followed in steps towards the sphere formation. The degeneration of the lens epithelium and the structures of the aLC in IC similar to Morgagnian globules were also observed. None of these structural changes were observed in NC.

CONCLUSIONS

We show by SEM and TEM that, in IC, LECs have pronounced structural features not observed in NC. This supports the hypothesis that the disturbed structure of LECs plays a role in water accumulation in the IC lens. We also suggest that, in IC, LECs produce bulging spheres that represent unique structures of degenerated material, extruded from the LEC.

Laser-assisted mini-capsulotomy: a new technique for intumescent white cataracts

PURPOSE

To describe a new two-step femtosecond laser-assisted technique for intumescent white cataracts.

METHODS

In 6 eyes with intumescent white cataracts, a laser-assisted mini-capsulotomy was performed first to release the intralenticular pressure. In the next step, the fluid milky lens material was removed from the anterior chamber before the eyes were re-docked to the laser system and a second larger anterior capsulotomy (4.5-mm diameter) was performed. Finally, the cataractous lens material was removed followed by intraocular lens implantation in the capsular bag.

RESULTS

In all cases, the laser system was able to identify and cut the anterior capsule without complications. Small residual tissue bridges were recognized after laser-assisted mini-capsulotomy in 2 eyes and solved with the dimple-down maneuver. The second, larger capsulotomy demonstrated satisfactory quality and a 360° overlap on the intraocular lens' optic was achieved in all cases.

CONCLUSIONS

This novel technique for intumescent white cataracts using a two-step laser-assisted mini-capsulotomy has the potential to avoid complications.