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.

Safety of air tamponade versus corneal hydration for sealing clear corneal incisions in cataract surgery.

PURPOSE: To compare safety of wound hydration to anterior chamber air tamponade for securing watertight closure of clear corneal incisions, during uneventful cataract surgery. METHODS: Prospective, comparative case-control series. Patients undergoing phacoemulsification were assigned to receive either anterior chamber air bubble (Group A) or intrastromal wound hydration with balanced salt solution (Group B) at the end of the procedure. Two high-volume surgeons operated equal number of cases in each group employing identical surgical technique, except for corneal side incision management. Patients were assessed pre- and postoperatively at day 1, day 4, day 9, and day 30 after surgery. RESULTS: One hundred eyes of 100 patients were enrolled, of which 2 were lost to follow-up. The two groups were comparable in terms of preoperative risk factor assessment, baseline central corneal thickness (CCT), preoperative endothelial cell density, as well as cumulative dissipated energy and duration of phacoemulsification (p > 0.05). Mean CCT and best-corrected visual acuity were better in Group B on the first postoperative day, but did not differ between the two groups at all other timepoints. Surgically induced astigmatism was comparable in the two groups (p > 0.05). Endothelial cell density loss at 1 month postoperatively was greater in Group A (34.06%) compared to Group B (16.45%). CONCLUSIONS: Wound sealing with intrastromal hydration proved to be safer than air tamponade in terms of preserving endothelial cell density and function.

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.

The potential role of nutrition on lens pathology: a systematic review and meta-analysis.

Oxidative stress is one of the main mechanisms of lens opacification, and certain nutritional antioxidants are suspected to have a protective effect. To examine the role of these nutritional antioxidants on cataract prevention, we searched major databases and reviewed current evidence regarding the protective effect of nutritive antioxidants. We included observational studies that investigate the association between one or more of the following micronutrients and cataract: vitamin A, vitamin C, vitamin E, lutein, zeaxanthin, α- and ß-carotene. Two independent authors extracted data and assessed their quality. We pooled results for overall cataract incidence for all types of cataract and separately for nuclear, cortical, and posterior subcapsular cataract. We did not perform sensitivity analysis. Twenty-five studies were included in the qualitative and 24 in the quantitative part of the study, with a total of 295,821 participants over 30 years old. Results from pooled analysis showed a protective effect of antioxidants on cataract, but not all of them reached statistical significance. Statistically significant results were reached for vitamin C (odds ratio [OR] = 0.88, 95% confidence interval [CI] [0.81, 0.97]), beta-carotene (OR = 0.89, 95% CI [0.83, 0.95]), and lutein and zeaxanthin (OR = 0.92, 95% CI [0.85, 0.99]). We did not find statistically significant results for vitamin E (OR = 0.84, 95% CI [0.70, 1.01]), vitamin A (OR = 0.90, 95% CI [0.80, 1.00]), or alpha-carotene (OR = 0.92, 95% CI [0.85, 1.00]). The present study shows a relation between certain antioxidants and cataract, but further studies, especially interventional, are needed to confirm this hypothesis.

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.

Investigation into the quantitative and qualitative characteristics of choroidal melanoma through magnetic resonance imaging and B-scan ultrasound.

OBJECTIVE: To investigate the homogeneity and vascularity of choroidal melanoma through magnetic resonance imaging (MRI) and brightness modulation (B-mode) ultrasound scan and their correlation with dimensions of tumor, as well as to measure the sensitivity of both modalities in retinal detachment (RD) detection. MATERIALS AND METHODS: This retrospective chart review included patients diagnosed with choroidal melanoma. All these patients underwent MRI scans using T2-weighted (T2-WI) and T1-weighted (T1-WI) sequences, before and after an intravenous injection of paramagnetic contrast material. The patients were also examined using a B-mode ultrasound scan, and the results from both modalities were compared (tumor homogeneity, tumor height, tumor base diameter, and tumor vascularity). RESULTS: Forty-two patients (mean age=65.33±12.51 years) with choroidal melanoma were included in the study. Homogeneity was confirmed in 16 patients through ultrasound scan, in 19 patients through T1-WI sequence, in 21 patients through T2-WI sequence, and in 25 patients through T1-WI sequence + contrast (gadolinium). Patients with homogenous tumors presented with lower (P=0.0045) mean height than that of those with nonhomogenous tumors, whereas no statistically significant difference was found for base diameter measurements (P=0.056). Patients with tumors of high vascularity presented with greater mean height (P=0.000638) and greater mean base diameter compared with those with tumors of low vascularity (P=0.019543). RD was detected in 26 patients through T1-WI sequence, in 13 patients through T2-WI sequence, in 26 patients through T1-WI sequence + contrast, and in 32 patients through ultrasound scan, which proved to be the most sensitive modality. CONCLUSION: The height of choroidal melanoma was positively correlated with tumor's homogeneity. Melanomas of greater height were found to be less homogenous, due to increased degeneration and higher occurrence of intratumoral hemorrhage. In addition, choroidal melanoma's height was also positively correlated with the level of its vascularity. Finally, ultrasound scan was found to be more sensitive than MRI in the detection of RD.

In Vitro Study of the Deturgescence Ability of Cultivated Human Corneal Endothelial Cells.

PURPOSE: To evaluate the efficiency of cultivated human corneal endothelial cells (HCECs) to dehydrate the cornea, using models of the posterior cornea, composed of artificial collagen mass (to represent corneal stroma) and equine collagen membranes (to represent Descemet membrane). METHODS: HCECs were isolated from donor corneal rings and cultivated at 37°C in 5% CO2 and 95% humidified air. The study design included 4 different sets of models: in set 1, the HCECs were placed directly on the collagen mass complex; in set 2, HCECs were placed on a thin equine collagen membrane and laid over the collagen mass; in set 3, HCECs were placed on a thick equine collagen membrane laid over the collagen mass; and in set 4 (the control group), the hydrophilic collagen mass was left alone to interact with the nutritional medium. The minimum thickness of each sample was measured with optical coherence tomography directly before placement of cells and after exposure to the nutritional fluid for 48 hours. RESULTS: After 2 days of exposure to the nutritional medium, the percentage decreases in thickness in "posterior cornea" models were 66% for set 1, 57% for set 2, and 13% set 3. In the control set, measurement of thickness after 2 days of exposure was not possible because of excessive fluid absorption. CONCLUSIONS: This in vitro study of HCECs showed that the dehydrating ability of HCECs is adversely affected by increased thickness of the artificial (Descemet) membrane. Further studies with similar models would aid better understanding of corneal diseases.

Contribution of integrated teaching in the improvement of an undergraduate ophthalmology curriculum.

PURPOSE: Conventional medical curriculum is the rule of medical teaching in Greek Medical Schools. Medical students are often taught irrelevant details with little or no reference to their potential clinical significance. Alternatively, integrated teaching warrants that the complete teaching material is covered by each faculty member not considering areas of personal expertise. The aim of this study was to evaluate the implementation of integrated teaching in ophthalmic training. METHODS: The main outcome measures of this retrospective study were a) comments and recommendations made anonymously by the fifth-year medical students in the evaluation questionnaires filled in at the end of their training, and b) scores obtained by students in their final examination at the end of their training in the 2nd Department of Ophthalmology as part of the core Curriculum of the Medical School of the Aristotle University of Thessaloniki. The latter outcome was analyzed with respect to the implementation of integrated teaching. RESULTS: The score obtained by students in the final examination, which is an objective outcome measure, increased significantly after the implementation of integrated teaching. The final grade (scores out of 10) of students who were trained with the integrated system (6.17±1.67, mean ± standard deviation) was significantly higher compared to those (5.52±2.20) trained with the conventional system (P<0.001). The positive outcome of this process was evident as there was a significant increase in the number of students satisfied with the teaching process compared to previous academic years. CONCLUSION: Based on the experience of eight academic years and as a result of interactive assessment process our department has modified its medical student teaching process from conventional to integrated; all teaching staff members are involved in the teaching process, while students are divided in small groups. In conclusion, integrated teaching in small student groups appears to be an efficient teaching method (for both theoretical and clinical skills) of ophthalmic training for medical students.

Measurements of elastic modulus for human anterior lens capsule with atomic force microscopy: the effect of loading force.

The purpose of the study was to appraise the effect of loading force magnitude on the determination of the elastic modulus of the anterior lens capsule through atomic force microscopy. Four human anterior lens capsules taken during phacoemulsification cataract surgery were studied, free of epithelial cells, with atomic force microscopy. For the experiment, five different indentation loading forces were applied to near areas of the specimen. Experimental data was exported and analyzed according to the Hertz model to obtain the Young's modulus with regards to the elastic behavior of the material. Force-distance curves were acquired by applying a load of 2, 5, 10, 20 and 30 nN. When examining the results it was evident that determination of Young's modulus of the anterior lens capsule is dependent on the loading force concerning the examined range. Loading forces of 10 and 20 nN led to results without significant difference (p > 0.05) and more reproducible (coefficients of variation 12.4 and 11.7 %, respectively).

Imaging characteristics of delayed surface calcification in hydrophilic intraocular lens models.

We report two cases of opacified explanted intraocular lenses (IOL).The first lens was explanted from a cataract patient, then treated in vitro with trypsin/ethylene-diamine-tetra-acetic acid. The second hydrophilic acrylic IOL was explanted from a patient who had undergone sulphur hexafluoride (SF6) gas endotamponade surgery to repair a retinal detachment.

Surgical outcomes in phacoemulsification after application of a risk stratification system.

BACKGROUND: The purpose of this study was to determine whether application of a risk stratification system during preoperative assessment of cataract patients and subsequent allocation of patients to surgeons with matching experience may reduce intraoperative complications. METHODS: Nine hundred and fifty-three consecutive patients (1109 eyes) undergoing phacoemulsification cataract surgery were assigned to two groups, ie, group A (n = 498 patients, 578 eyes) and group B (n = 455 patients, 531 eyes). Patients from group A were allocated to surgeons with varying experience with only a rough estimate of the complexity of their surgery. Patients from group B were assigned to three risk groups (no added risk, low risk, and moderate-high risk) according to risk factors established during their preoperative assessment and were respectively allocated to resident surgeons, low-volume surgeons, or high-volume surgeons. Data were collected and entered into a computerized database. The intraoperative complication rate was calculated for each group. RESULTS: The intraoperative complication rate was significantly lower in group B than in group A (group A, 5.88%; group B, 3.2%; P < 0.05). Patients from group B with no added risk and allocated to resident surgeons had a significantly lower rate of intraoperative complications than those from group A allocated to resident surgeons (group A, 7.2%; group B, 3.08%; P < 0.05). CONCLUSION: Our study demonstrates that allocation of cataract patients to surgeons matched for experience according to a uniform and reliable preoperative assessment of their risk of complications allows for better surgical outcomes, especially for resident surgeons.

Binocularity enhances visual acuity of eyes implanted with multifocal intraocular lenses.

PURPOSE: To investigate the effect of binocularity on long-term visual acuity in patients who have undergone bilateral implantation of a presbyopia-correcting diffractive multifocal intraocular lens (IOL). METHODS: Twenty patients (9 men and 11 women) with an average age of 70 ± 7 years (range: 56 to 78 years) underwent bilateral implantation of a diffractive multifocal IOL (AcrySof IQ ReSTOR IOL, SN60D3; Alcon Laboratories, Inc., Fort Worth, TX). Uncorrected visual acuity was measured monocularly and binocularly on average 26 ± 6 months following implantation in the second eye (range: 17 to 40 months) using the University of Crete European-wide modified Early Treatment Diabetic Retinopathy Study charts at the following distances: (1) 4 m, uncorrected distance visual acuity (UDVA), (2) 66 cm, uncorrected intermediate visual acuity (UIVA), and (3) 33 cm, uncorrected near visual (UNVA). RESULTS: Mean ± standard deviation UDVA was 0.07 ± 0.10 and 0.21 ± 0.12 logMAR (20/23 and 20/32 Snellen) in the better and worse eye, respectively, improving to 0.00 ± 0.09 logMAR (20/20 Snellen) binocularly. Mean ± standard deviation UIVA was 0.18 ± 0.14 and 0.32 ± 0.15 logMAR (20/30 and 20/42 Snellen) in the better and worse eye, respectively, improving to 0.08 ± 0.15 logMAR (20/24 Snellen) binocularly. Mean ± standard deviation UNVA was 0.20 ± 0.09 and 0.32 ± 0.12 logMAR (20/32 and 20/42 Snellen) in the better and worse eye, respectively, improving to 0.11 ± 0.10 logMAR (20/26 Snellen) binocularly. Binocular summation, defined as the difference between the binocular and better eye visual acuity, was found to be statistically significant at all distances: 0.07 ± 0.05 logMAR at 4 m, 0.10 ± 0.11 logMAR at 66 cm, and 0.09 ± 0.08 logMAR at 33 cm. CONCLUSIONS: The results confirm that there is substantial benefit of binocular vision in individuals with bilateral multifocal IOL implantation in terms of increased visual acuity. This effect is evident at all distances.

A novel mechanism of UV-A and riboflavin-mediated corneal cross-linking through induction of tissue transglutaminases.

PURPOSE: Collagen cross-linking using UV-A irradiation combined with the photosensitizer riboflavin is a new technique for treating progressive keratoconus. The purposes of this study were to examine whether primary human corneal keratocytes (HCKs) are capable of expressing and secreting fibronectin and tissue transglutaminase (tTgase), an enzyme cross-linking extracellular matrix protein, and to examine whether fibronectin and tTgase are increased after the treatment of HCK cells with UV-A irradiation combined with riboflavin (RFUV-A), thus providing another possible physiological mechanism of the cross-linking pathway. METHODS: Cell cultures established from HCKs were treated with 0.025% riboflavin solution and UV-A (370 nm) irradiance 3 mW/cm2 for 30 minutes. Induction of fibronectin and tTgase was investigated by immunohistochemistry, real-time polymerase chain reaction, and Western blot analysis. Cell viability was quantified by a microscopic live-dead assay. External tTgase activity was measured by the ability to form polymerized fibronectin and the incorporation of biotinylated cadaverine into fibronectin. RESULTS: Treatment of cultured HCK cells with RFUV-A increased the fibronectin and tTgase messenger RNA and protein levels. This effect was not observed in cells treated with riboflavin or UV-A radiation alone. Incorporation of biotinylated cadaverine was significantly increased when HCK cells were treated with RFUV-A. CONCLUSIONS: The enzymes tTgase and fibronectin are expressed by RFUV-A treatment in cultured HCK cells. This mechanism provides more information about the physiology of corneal cross-linking.

Air toxicity for primary human-cultured corneal endothelial cells: an in vitro model.

PURPOSE: To investigate the possible toxic effect of air exposure for an in vitro model of primary human corneal endothelial cells (HCECs). METHODS: Primary HCECs were isolated from donor corneal rings and cultivated at 37°C in 5% CO2 and 95% humidified air. Six groups of HCEC cultures were set up, and 4 samples were enclosed in each group: group 1 consisted of samples in which HCECs were exposed to air for 30 minutes. Group 2 consisted of HCECs exposed to air for 1 hour, group 3 for 3 hours, group 4 for 6 hours, group 5 for 12 hours, and group 6 for 24 hours. RESULTS: Three hours after exposure, the morphology of the cells was still intact; however, a few cells within the monolayer appeared enlarged and exhibited characteristics of more senescent cells. Six hours after exposure to air, the endothelial cells started losing their typical hexagonal morphology and appeared enlarged and compromised. Viability was superior to 95% in groups 1 to 3, whereas for groups 4, 5, and 6 was 71%, 22.4%, and 6.3%, respectively. CONCLUSION: The present study illustrates that the toxic effect of air exposure for the studied in vitro model of primary human-cultured corneal endothelial cells is not significant for the period of 3 hours, whereas after 6 hours it starts to induce major apoptotic mechanisms, leading to reduced viability until the period of 24 hours where the percentage of living cells is drastically decreased.