The effect and safety of intravitreal injection of ranibizumab and bevacizumab on the corneal endothelium in the treatment of diabetic macular edema.

OBJECTIVE: To investigate the effect and safety of intravitreal injection (IVI) of bevacizumab and ranibizumab on corneal endothelial cell count and morphology in patients with diabetic macular edema. MATERIALS AND METHODS: A total of 60 eyes from 60 consecutive patients who received 0.5 mg/0.05 ml IVIs of bevacizumab (n = 30, IVB group) or 1.25 mg/0.05 ml ranibizumab (n = 30, IVR group) for three consecutive months were investigated prospectively. Specular microscopy was performed to evaluate endothelial cell count, the percentage of hexagonal cells (pleomorphism), and the coefficient of variation of the cell size (polymegathism); optical biometry was performed to evaluate central corneal thickness. Results before injection and 1 month after the first and third injections were compared. RESULTS: The groups were matched for age (p = 0.11) and gender (p = 0.32). There was no significant difference in endothelial cell count (IVB group, p = 0.66; IVR group, p = 0.74), pleomorphism (IVB group, p = 0.44; IVR group, p = 0.88) and polymegathism (IVB group, p = 0.21; IVR group, p = 0.24) before injection or 1 month after the first and third injections. There was also no difference in central corneal thickness (IVB group, p = 0.15; IVR group, p = 0.58) before injection or 1 month after the first and third injections. CONCLUSION: Monthly 1.25 mg/0.05 ml IVIs of bevacizumab or 0.5 mg/0.05 ml of ranibizumab for three consecutive months in the treatment of diabetic macular edema does not affect corneal morphology and has no harmful effects on the endothelium.

Measurements of central corneal thickness and endothelial parameters with three different non-contact specular microscopy devices.

We aimed to compare the measurements of central corneal thickness (CCT) and endothelial parameters with three different non-contact specular microscopy (SM) devices. Fifteen eyes of 15 healthy individuals (6 males; 9 females) were enrolled in the study. Mean age was 37.93 ± 15.13 years. Endothelial parameters and CCT were measured with Nidek CEM-530, Topcon SP-3000P, and Tomey EM-3000 SM devices by the same physician. Endothelial parameters included endothelial cell count (ECC), maximum, minimum, and average endothelial cell size. and hexagonality ratio. There were no statistically significant differences in ECC, CTT, and average endothelial size (AES) between the devices (p > 0.05). The measurement of maximum endothelial size (MES) was different between Nidek SM and Topcon SM devices (p = 0.001), but there was no difference in MES between Nidek SM and Tomey SM (p = 0.058), and between Topcon SM and Tomey SM (p = 0.081). There was no difference in minimum endothelial size (MinES) between Nidek SM and Topcon SM (p = 0.794); however, there was a significant difference in MinES between Tomey SM and Nidek SM (p < 0.001), and between Tomey SM and Topcon SM (p < 0.001). Comparison of hexagonality ratio showed statistically significant difference between the devices (p < 0.001). No significant differences in the measurements of ECC, CCT, and AES were detected between different SM devices, whereas a statistically significant difference in hexagonality ratio was detected between the devices. These devices should not be used alternatively in the endothelial morphology assessment in patient's follow-up.

Effects of age and breed on corneal thickness, density, and morphology of corneal endothelial cells in enucleated sheep eyes.

OBJECTIVE: The purpose of the study was to determine corneal thickness (CT), endothelial cell density (ECD), morphology, and morphometry in ovine eyes, and to report the effects of age and breed on these parameters. ANIMALS STUDIED AND PROCEDURES: Forty-eight healthy ovine eyes were classified into six groups (eight eyes per group) according to animals' age (lambs and adults) and breed (Manchega, Ripollesa, and Rasa Aragonesa). Endothelial cell density (cells/mm(2) ) and CT (µm) were calculated in the central cornea and four peripheral quadrants by means of specular microscopy. Mean cell area (MCA (µm(2) )), pleomorphism (% hexagonal cells), and polymegethism (CV) were evaluated in the central cornea. Statistics consisted of an ANOVA model and a LSD test for the post hoc analysis. RESULTS: Results in lambs were as follows: ECD = 3532 ± 259, CT = 699 ± 56, MCA = 283 ± 22, % hexagonal cells = 75.64 ± 3.09, and CV = 18 ± 8.4; and in adults: ECD = 2204 ± 261, CT = 804 ± 87, MCA = 473 ± 53, % hexagonal cells = 69.9 ± 3.42, and CV = 18.1 ± 5.2. There were differences (P < 0.001) in all parameters studied between both groups except for the CV (P = 0.962). Regarding the breed, Rasa Aragonesa presented a higher CT (P = 0.001) and CV (P = 0.04) compared to other breeds. Mean values of all groups together showed that central and dorsal areas of the cornea were the thickest, whereas temporal quadrant was the thinnest (P < 0.001). CONCLUSIONS: This study demonstrates that age and breed influence corneal and endothelial parameters in sheep.

[Corneal thickness and endothelial observation for youth myopia patients fitted with ortho-k lens for seven years].

OBJECTIVE: To observe the changes of the corneal thickness and endothelial cell for youth myopia patients fitted with long-term orthokeratology (Ortho-K, OK). METHODS: Retrospective case series study. During 2000 to 2005, 30 patients with OK lens wearing more than seven years in the Bei Yi Optometry & Ophthalmology Center had been chose in this study, and all the right eye of each person was selected for retrospective case statistics (30 eyes). the measure instruments, including A scan pachymeter and endothelium microscope, were used to the long-term continuous supervise, which involved the central and para-peripheral corneal thickness, corneal endothelium and corneal conjunctival complications rate. Then the 30 patients were divided into two groups: the moderate-low myopia group is less than -4.00 D with 12 patients (24 eyes), and the high myopia group is more than -5.00 D with 10 patients (20 eyes). And the difference between two groups was involved in this research. The one-way analysis of variance was used to compare before, after six months, after one year, after three years, after five years and after seven years OK lens wearing for the patients. And the variance analysis was used to compare between moderate-low and high myopia groups. RESULTS: Corneal thickness analysis during these seven years: the average central corneal thickness before and after seven-years wearing are (549.45 ± 33.72) and (538.97 ± 34.28) µm, respectively, and the central corneal thickness had no significant changes (F = 1.749, P = 0.076); The corneal thickness of nasal, superior, temporal and inferior also had no significant changes (P > 0.05). The average corneal endothelial cell densities before and after seven-years wearing are (3188.53 ± 272.25) and (3186.64 ± 278.69) num/mm(2), respectively, and the corneal endothelial cell density had no significant changes during seven years wearing (F = 2.204, P = 0.088). The average hexagonal cell ratio before and after seven-years wearing are 66.18% ± 6.42% and 64.65% ± 8.03%, respectively, and the hexagonal cell ratio had no significant changes during seven-years wearing (F = 2.097, P = 0.085). The average cell area and coefficient of variation also had no significant change during seven-years wearing (F = 2.143, 2.114; P > 0.05). There was also no statistics significance between moderate-low and high myopia of the endothelial cell and the corneal thickness change with long-term OK lens wearing. The slight corneal conjunctival complication was occurred during seven-year wearing, such as corneal fluorescence stain (less than 7%), and no serious complication was happened during seven-year wearing. CONCLUSIONS: In generally, it is safety for youth with long-term scientific and standardized wearing high Dk material orthokeratology contact lens.

Histology, histochemistry and ultrastructure of cornea of domestic pigs (Sus scrofa domesticus).

A comprehensive light and ultrastructural examination of the cornea in Domestic Pigs (Sus scrofa domesticus) revealed four distinct layers: the anterior epithelium, corneal stroma, Descemet's membrane and endothelium. Although Bowman's layer was not distinctly identified through histology, histochemical analysis indicated the presence of a rudimentary Bowman's layer, possibly vestigial from evolution. Scanning electron microscopy of the outer corneal surface unveiled two cell types, characterized by micro-projections, with light cells exhibiting shorter, thicker projections compared to dark cells. Examination of the inner surface via scanning electron microscopy demonstrated an endothelial layer devoid of cilia and microvilli, yet faint round to oval elevations were observed, potentially representing cell nuclei. Transmission electron microscopy unveiled that basal cells of the anterior epithelium closely adhered to the basement membrane, featuring half desmosomes along the basal surface. These basal cells extensively interconnected through interdigitations and a few desmosomes. The superficial cell layer consisted of a few rows of closely attached flat cells, forming a leak-proof layer with zona occludens. The outermost cells of this layer displayed fine projections to enhance the surface area, facilitating tear film distribution. At lower magnification, Transmission electron microscopy of the corneal stroma revealed alternating light and dark bands, with light bands representing transverse sections of collagen fibril lamellae and dark bands corresponding to longitudinal or oblique sections. Spindle-shaped keratocytes (fibroblasts) were identified as the primary stromal cells, intermingled between the lamellae, and featured long processes in close contact with neighbouring keratocytes. Overall, the histomorphology of the pig cornea resembles that of the human cornea except indistinct Bowman's membrane. This detailed understanding of the normal corneal structure in pigs hold great significance for biomedical research, providing a valuable reference for studies involving this animal model.

Predictive value of optical coherence tomography in graft attachment after Descemet's membrane endothelial keratoplasty.

PURPOSE: To evaluate the predictive value of early anterior segment optical coherence tomography (AS-OCT) on graft adherence or detachment after Descemet's membrane endothelial keratoplasty (DMEK). DESIGN: Retrospective study of prospectively collected data at a tertiary referral center. PARTICIPANTS: A total of 87 eyes of 87 patients of a consecutive series of 142 DMEK surgeries. METHODS: Anterior segment OCT was performed within the first hour after DMEK and at 1 week, 1 month, 3 months, and 6 months, and for each time interval detachments were classified as "none," ≤ 1/3 detachment, >1/3 detachment of the total graft surface area, or "complete" detachment. Throughout the study, no rebubbling procedures were performed. MAIN OUTCOME MEASURES: Graft adherence at various postoperative time intervals. RESULTS: One-hour AS-OCT scans were more accurate at predicting the final 6-month graft adherence status than those at 1 week or 1 month. Grafts showing complete attachment or <1/3 detachment at 1 hour remained stable or improved in 73% of the cases at 1 week, 82% at 1 month, 86% at 3 months, and 90% at 6 months. All grafts attached at 1 week remained attached at 6 months. Graft detachments of >1/3 at 1 hour showed reattachment at 6 months in 25% of the cases, whereas 67.5% of the cases showed a persistent detachment of >1/3 at 6 months and 12.5% showed a complete detachment. CONCLUSIONS: The 1-hour AS-OCT scan showed the best predictive value on 6-month graft adherence status. The combined information of the 1-hour and 1-week AS-OCT scans may facilitate decision making about surgical reintervention after DMEK.

The measurement of corneal thickness from center to limbus in vivo in C57BL/6 and BALB/c mice using two-photon imaging.

The mouse corneal thickness is very important for research into the fields of eye disease. However, the in vivo corneal thickness for the entire cornea from the pupil to the limbus was not determined. We measured in vivo corneal layer thicknesses in different corneal areas, from the central cornea to the limbus, in the widely used inbred C57BL/6 and BALB/c mouse strains using two-photon (2 PH) imaging. Eight corneas of the C57BL/6 or BALB/c were scanned using a 2 PH laser scanning fluorescence microscopy system. A total of 14 thicknesses of the different corneal layers, from different corneal regions, were measured using image processing software. In both C57BL/6 and BALB/c mice, the thickness of the corneal layers was inhomogeneous in different areas of the cornea, and all of the layers had their minimum thickness at the limbus. In C57BL/6 mice, the thickness of the corneal layers gradually increased from the central to the paracentral cornea, peaked at the fifth measurement point in the paracentral area, and decreased from this point to the limbus. In BALB/c mice, the thickness of the entire cornea and corneal epithelium had its maximum at the central cornea and gradually decreased from the central cornea to the peripheral cornea and to the limbus. The thickness of the corneal stroma and endothelium had its maximum at the fourth measurement point in the paracentral cornea and gradually decreased from the paracentral cornea to the limbus. The ratio of epithelial thickness to the total corneal thickness gradually decreased from the central cornea to the limbus in both C57BL/6 and BALB/c mice. The minimum ratio was observed at the fourteenth measurement point in both C57BL/6 and BALB/c mice. The ratio of stromal and endothelial to the total corneal thickness gradually increased from the central cornea to the limbus in both C57BL/6 and BALB/c mice. The maximum ratio was observed at the fourteenth measurement point in C57BL/6 mice. The ratio at the first eight measurement points was significantly lower in BALB/c than in C57BL/6 mice (P < 0.05). Our study demonstrated that the thickness of the entire cornea, the corneal epithelium, the corneal stroma and the endothelium was inhomogeneous in different areas of the cornea. Moreover, all of the layers exhibited a minimum thickness at the limbus in both C57BL/6 and BALB/c mice. Furthermore, the corneal thickness in different areas varied between C57BL/6 and BALB/c mice, and the variation in thickness with respect to corneal location for these strains was dissimilar. When using the mouse as an animal model to examine the cornea, it is important to note the differences between humans and mice.

Comparative analysis of the relationship between anterior and posterior corneal shape analyzed by Scheimpflug photography in normal and keratoconus eyes.

BACKGROUND: To analyze and compare the relationship between anterior and posterior corneal shape evaluated by a tomographic system combining the Scheimpflug photography and Placido-disc in keratoconus and normal healthy eyes, as well as to evaluate its potential diagnostic value. METHODS: Comparative case series including a sample of 161 eyes of 161 subjects with ages ranging from 7 to 66 years and divided into two groups: normal group including 100 healthy eyes of 100 subjects, and keratoconus group including 61 keratoconus eyes of 61 patients. All eyes received a comprehensive ophthalmologic examination including an anterior segment analysis with the Sirius system (CSO). Antero-posterior ratios for corneal curvature (k ratio) and shape factor (p ratio) were calculated. Logistic regression analysis was used to evaluate if some antero-posterior ratios combined with other clinical parameters were predictors of the presence of keratoconus. RESULTS: No statistically significant differences between groups were found in the antero-posterior k ratios for 3-, 5- and 7-mm diameter corneal areas (p ≥ 0.09). The antero-posterior p ratio for 4.5- and 8-mm diameter corneal areas was significantly higher in the normal group than in the keratoconus group (p<0.01). The k ratio for 3, 5, and 7 mm was significantly higher in the keratoconus grade IV subgroup than in the normal group (p<0.01). Furthermore, significant differences were found in the p ratio between the normal group and the keratoconus grade II subgroup (p ≤ 0.01). Finally, the logistic regression analysis identified as significant independent predictors of the presence of keratoconus (p<0.01) the 8-mm anterior shape factor, the anterior chamber depth, and the minimal corneal thickness. CONCLUSIONS: The antero-posterior k and p ratios are parameters with poor prediction ability for keratoconus, in spite of the trend to the presence of more prolate posterior corneal surfaces compared to the anterior in keratoconus eyes.

Precision analysis of posterior corneal topography measured by Visante Omni: repeatability, reproducibility, and agreement with Orbscan II.

PURPOSE: To evaluate the repeatability and reproducibility of posterior corneal curvature and posterior corneal elevation best-fit sphere (BFS) obtained with the Visante Omni (Carl Zeiss Meditec) and to compare the results with the Orbscan II (Bausch & Lomb). METHODS: Thirty eyes from 30 healthy volunteers were included in this study. All patients were examined 5 times with the Visante Omni and Orbscan II by 2 independent operators. The posterior corneal curvature (3- and 6-mm zone) and posterior corneal elevation BFS (5- and 8-mm zone) were generated for each system. Intraoperator repeatability and interoperator reproducibility and agreement between the systems were evaluated using the intraclass correlation coefficient (ICC) and the Bland-Altman method. RESULTS: The repeatability of posterior corneal curvature and posterior corneal elevation BFS measured by the Visante Omni was high for all analysis zones (ICC, 0.99 to 1.00). The reproducibility also showed similar results (ICC, 0.99 to 1.00). Agreement between the Visante Omni and Orbscan II was high for posterior corneal curvature (ICC, 0.94 to 0.97) and posterior corneal elevation BFS (ICC, 0.96 to 0.98) with 95% limits of agreement at -0.26 to 0.22 diopters for posterior corneal curvature and 0.11 to 0.69 mm for posterior corneal elevation BFS. CONCLUSIONS: The Visante Omni provides good repeatability and reproducibility of posterior corneal topography. Overall agreement with the Orbscan II system was high.

Optimization of immunolocalization of cell cycle proteins in human corneal endothelial cells.

PURPOSE: En face observation of corneal endothelial cells (ECs) using flat-mounted whole corneas is theoretically much more informative than observation of cross-sections that show only a few cells. Nevertheless, it is not widespread for immunolocalization (IL) of proteins, probably because the endothelium, a superficial monolayer, behaves neither like a tissue in immunohistochemistry (IHC) nor like a cell culture in immunocytochemistry (ICC). In our study we optimized IL for ECs of flat-mounted human corneas to study the expression of cell cycle-related proteins. METHODS: We systematically screened 15 fixation and five antigen retrieval (AR) methods on 118 human fresh or stored corneas (organ culture at 31 °C), followed by conventional immunofluorescence labeling. First, in an attempt to define a universal protocol, we selected combinations able to correctly localize four proteins that are perfectly defined in ECs (zonula occludens-1 [ZO-1] and actin) or ubiquitous (heterogeneous nuclear ribonucleoprotein L [hnRNP L] and histone H3). Second, we screened protocols adapted to the revelation of 9 cell cycle proteins: Ki67, proliferating cell nuclear antigen (PCNA), minichromosome maintenance protein 2 (MCM2), cyclin D1, cyclin E, cyclin A, p16(Ink4a), p21(Cip1) and p27(Kip1). Primary antibody controls (positive controls) were performed on both epithelial cells of the same, simultaneously-stained whole corneas, and by ICC on human ECs in in vitro non-confluent cultures. Both controls are known to contain proliferating cells. IL efficiency was evaluated by two observers in a masked fashion. Correct localization at optical microscopy level in ECs was define as clear labeling with no background, homogeneous staining, agreement with previous works on ECs and/or protein functions, as well as a meaningful IL in proliferating cells of both controls. RESULTS: The common fixation with 4% formaldehyde (gold standard for IHC) failed to reveal 12 of the 13 proteins. In contrast, they were all revealed using either 0.5% formaldehyde at room temperature (RT) during 30 min alone or followed by AR with sodium dodecyl sulfate or trypsin, or pure methanol for 30 min at RT. Individual optimization was nevertheless often required to optimize the labeling. Ki67 was absent in both fresh and stored corneas, whereas PCNA was found in the nucleus, and MCM2 in the cytoplasm, of all ECs. Cyclin D1 was found in the cytoplasm in a paranuclear pattern much more visible after corneal storage. Cyclin E and cyclin A were respectively nuclear and cytoplasmic, unmodified by storage. P21 was not found in ECs with three different antibodies. P16 and p27 were exclusively nuclear, unmodified by storage. CONCLUSIONS: IL in ECs of flat-mounted whole human corneas requires a specific sample preparation, especially to avoid overfixation with aldehydes that probably easily masks epitopes. En face observation allows easy analysis of labeling pattern within the endothelial layer and clear subcellular localization, neither of which had previously been described for PCNA, MCM2, or cyclin D1.

Optimizing Visualization of Descemet Membrane Endothelial Keratoplasty Tissue: Assessing the Impact of Trypan Blue Exposure on Stain Duration and Corneal Endothelial Cell Function.

PURPOSE: To assess how trypan blue staining affects Descemet membrane endothelial keratoplasty (DMEK) graft visibility and corneal endothelial cell (CEC) mitochondrial respiration. METHODS: DMEK grafts (n = 20) were stained with trypan blue 0.06% for 1, 3, 5, or 10 minutes. Each graft was injected into an artificial anterior chamber. Surgery was simulated with tapping and sweeping motions on the corneal surface and injections of balanced salt solution (BSS). Graft visibility was assessed at 5, 10, 20, and 30 minutes. Effects of trypan blue on mitochondrial respiration were assessed using primary CECs cultured from donor corneas (n = 43). Treatment wells exposed to trypan blue 0.06% (1, 5, or 30 minutes) and donor-matched control wells to methylene blue 1% (1 minute) or BSS (1, 5, or 30 minutes) were assayed for key respiration parameters. RESULTS: After 5 minutes of surgical manipulation, grafts stained for 5 minutes were significantly more visible than grafts stained for 1 or 3 minutes; there was no added benefit of staining for 10 minutes. After 10 minutes of surgical manipulation, grafts stained for 3 minutes were more visible than grafts stained for 1 minute, without additional benefits of staining ≥5 minutes. No visibility differences were observed after ≥20 minutes of surgical manipulation. CEC mitochondrial respiration did not change significantly following trypan blue exposure for all intervals tested compared to BSS. CONCLUSIONS: Staining DMEK grafts with trypan blue for 3 to 5 minutes optimizes visibility during surgical manipulation without mitochondrial impairment. Corneal surgeons learning DMEK will benefit from optimizing this critical step.

In-vivo Three-dimensional Characteristics of Bowman's Layer and Endothelium/Descemet's Complex Using Corneal Microlayer Tomography in Healthy Subjects.

Purpose: To characterize the three-dimensional (3D) thickness profile and age-related changes of Bowman's layer (BL), and endothelium/Descemet's membrane (En/DM) complex among healthy individuals using Corneal Microlayer Tomography (CML-T), and to describe its repeatability and accuracy.Methods: Sixty-six eyes of 41 healthy volunteers; 27 eyes (< 40 years old), and 39 eyes (>40 years old) were imaged using HD-OCT. Automatic and manual segmentation of the corneal layers was performed, and 3D thickness maps were generated, using custom-built CML-T software. A regional analysis of mean thickness parameters between the 2 age groups was performed. A regression analysis was used to assess the correlation between age, and thickness maps. Intraclass Correlation Coefficients (ICC), Coefficients of Variation (COV), and Bland-Altman plots were used to assess the reliability of the repeated measurements in 198 locations.Results: CML-T successfully mapped the BL and En/DM in all included eyes. Thickness maps showed a significant increase in corneal thickness (CT), BL thickness (BMT), and En/DM complex thickness (DMT) toward the periphery with a mean difference 28 µm (p < .001), 1.1 µm (p < .001), and 1.4 µm (p < .001), respectively. There was a strong correlation between age and central DMT (r = 0.61; p < .001), while there was no correlation between age and both CT, and BMT. ICC values ranged from 0.9 (BMT) to 0.997 (DMT), and from 0.808 (BMT) to 0.979 (CT) for intraoperator repeatability of manual measurements, and the accuracy of auto matic measurements, respectively. COV values were lower than 7.5% in all cases.Conclusion: CML-T is a novel tool that can generate 3D-thickness maps of both BL and En/DM. CT, BMT, and DMT increase toward the periphery in healthy corneas. DMT increases with aging, while BMT does not. We also report excellent repeatability, accuracy and good agreement between automatic and manual measurements.

'Acute-angled bevel' sign to assess donor lenticule orientation in ultra-thin descemet stripping automated endothelial keratoplasty.

A 6.5-year-old boy with congenital hereditary endothelial dystrophy underwent clear corneal ultra-thin descemet stripping automated endothelial keratoplasty (DSAEK). After graft insertion, it was difficult to assess graft orientation due to hazy cornea. Intraoperative optical coherence tomography (iOCT) showed a well-attached graft and the bevelled edge of donor lenticule made an acute angle with the overlying stroma. Postoperative anterior segment OCT confirmed the presence of acute-angled bevel sign. A wetlab experiment was performed with experimental corneoscleral tissues to confirm the findings. Donor lenticule was injected in the artificial chamber with stromal-side up as well as stromal side-down. 'Acute-angled bevel sign' was observed on iOCT in the experimental cases with stromal-side up. In inverse graft, the acute-angled bevel was not observed, instead the configuration was obtuse angled. Identifying the 'acute-angled bevel sign' on iOCT confirms correct graft orientation after unfolding and is extremely useful for hazy corneas and ultrathin DSAEK lenticules.

Validity of the keratometric index: evaluation by the Pentacam rotating Scheimpflug camera.

PURPOSE: To determine the keratometric index based on actual measurements of the anterior and posterior corneal surfaces using a rotating Scheimpflug camera (Pentacam, Oculus) and evaluate the accuracy of this keratometric index in estimating total and posterior corneal powers. SETTING: Departments of Ophthalmology, Taipei Medical University Hospital and Taipei City Hospital, Taipei, Taiwan. METHODS: The right eye of 221 subjects was measured with the Pentacam system. The radius of the best-fit sphere for the anterior corneal surface (rant) and posterior corneal surface (rpost), mean radius of simulated keratometry (rsimK), and central corneal thickness were obtained. The ratio of rant to rpost (AP ratio) and keratometric index were calculated in each eye. RESULTS: The means for rant, rpost, rsimK, and AP ratio were 7.75 mm +/- 0.28 (SD), 6.34 +/- 0.28 mm, 7.75 +/- 0.27 mm, and 1.223 +/- 0.034 mm, respectively. These parameters were normally distributed. The mean calculated keratometric index (Ncal) was 1.3281 +/- 0.0018. Using the keratometric indices of 1.3281 (Ncal), 1.3315 (Gullstrand schematic eye), and 1.3375 (conventional), the mean arithmetic and absolute estimation errors for the total corneal power were, 0.00 +/- 0.24 diopter (D) and 0.17 +/- 0.17 D, 0.43 +/- 0.23 D and 0.45 +/- 0.21 D, and 1.21 +/- 0.24 D and 1.21 +/- 0.24 D, respectively. The total corneal power was predicted to within +/-0.50 D of the actual value in 95.0%, 60.2%, and 0.9% of eyes, respectively. The mean arithmetic and absolute estimation errors for the posterior corneal power using an AP ratio of 1.223 (this study) or 1.132 (Gullstrand schematic eye) were 0.00 +/- 0.17 D and 0.13 +/- 0.12 D and 0.47 +/- 0.18 D and 0.47 +/- 0.17 D, respectively. The posterior corneal power was estimated to within +/-0.50 D of the actual value in 97.7% and 60.2% of eyes, respectively. CONCLUSION: Using the Pentacam-derived keratometric index improved the prediction accuracies of total and posterior corneal powers.

Corneal thickness, endothelial cell density, and morphological and morphometric features of corneal endothelial cells in goats.

OBJECTIVE To determine corneal thickness (CT), endothelial cell density (ECD), and morphological and morphometric features of caprine eyes and to assess effects of aging on these variables. SAMPLE 27 healthy eyes of 19 Murciano-Granadina goats. PROCEDURES Goats were classified into 2 age groups (kids, 14 months old [14 eyes]; and adults, 7 to 10 years old [13 eyes]). The ECD and CT were calculated in the central cornea and 4 peripheral quadrants. Mean cell area (MCA), pleomorphism (percentage of hexagonal cells), and polymegathism were evaluated in the central cornea. RESULTS Median values for kids were determined for ECD (3,831 cells/mm2; inter-quartile [25th to 75th percentile] range [IQR], 3,669 to 4,011 cells/mm2), CT (608 µm; IQR, 573 to 655 µm), MCA (255 µm2; IQR, 243 to 272 µm2), pleomorphism (80.53%; IQR, 78.83% to 83.30%), and polymegathism (19; IQR, 18 to 22). Median values for adults were determined for ECD (2,101 cells/mm2; IQR, 1,966 to 2,251 cells/mm2), CT (706 µm; IQR, 670 to 730 µm), MCA (466 µm2; IQR, 425 to 507 µm2), pleomorphism (67.80%; IQR, 65.50% to 70.00%), and polymegathism (21; IQR, 15 to 26). Values differed significantly between the 2 groups for all variables, except polymegathism. For both groups, the dorsal and temporal quadrants were the thickest and thinnest, respectively. Ventral ECD was the lowest for both groups. CONCLUSIONS AND CLINICAL RELEVANCE ECD decreased with age, whereas MCA, pleomorphism, and CT increased. Moreover, differences among regions of the cornea indicated that the central cornea should not be considered as representative of the entire cornea.

Endothelium-in Versus Endothelium-out Insertion With Descemet Membrane Endothelial Keratoplasty.

PURPOSE: To determine whether graft orientation during insertion affects Descemet membrane endothelial keratoplasty (DMEK) outcomes. METHODS: This was a retrospective analysis of 754 consecutive DMEK cases performed by 2 experienced surgeons to treat Fuchs dystrophy. Both surgeons used an intraocular lens insertor. One surgeon always inserted the tissue scrolled endothelium outward (group 1, n = 245). The other surgeon tested 3 methods: endothelium-outward scroll configuration (group 2, n = 161), endothelium-inward trifold configuration (group 3, n = 172), and trifold configuration with concurrent use of an anterior chamber maintainer (group 4, n = 176). The main outcome measures were rebubbling rate, regrafting or failure within 6 months, and 6-month endothelial cell loss. The tissue unfolding time from graft insertion to air fill was measured in a subset of 120 cases by 1 surgeon. RESULTS: The rebubbling rates were comparable across groups (ie, 12%, 10%, 10%, and 13% for groups 1, 2, 3, and 4, respectively, P = 0.21). The 6-month graft failure/replacement rates were comparable across groups (ie, 0.8%, 1.2%, 2.3%, and 0.6%, respectively, P = 0.18). Similarly, the 6-month endothelial cell loss did not differ significantly between groups (ie, 28% ± 11%, 30% ± 13%, 28% ± 15%, and 27% ± 13%, respectively, P = 0.019). In the subset analysis, the tissue unfolding time was similar for scroll and trifold configurations (6.0 ± 3.5 vs. 5.4 ± 3.0 minutes, respectively, P = 0.43). CONCLUSIONS: The outcomes were similar for endothelium-out and endothelium-in (trifold) insertion methods with DMEK, suggesting that the choice is a matter of surgeon preference.

Clinical Outcomes of Preloaded Descemet Membrane Endothelial Keratoplasty Grafts With Endothelium Tri-Folded Inwards.

PURPOSE: To evaluate the initial outcomes and complications of Descemet membrane endothelial keratoplasty (DMEK) using donor tissues tri-folded with the endothelium inwards, preloaded at the Eye Bank, and delivered with bimanual pull-through technique. DESIGN: Prospective, noncomparative, interventional case series. METHODS: Setting: Eye bank and tertiary care eye department. PATIENT POPULATION: Forty-six consecutive eyes of 41 patients with Fuchs endothelial dystrophy with or without cataract operated between November 2016 and March 2017. INTERVENTION: DMEK tissues prepared with SCUBA technique and punched to a diameter of 8.25 mm were preloaded with the endothelium tri-folded inwards in an intraocular lens (IOL) cartridge with a 2.2-mm opening filled with the same tissue culture medium contained in the vial used for shipment to the surgeon. Standardized DMEK was performed as a single procedure (n = 15) or in combination with phacoemulsification and IOL implantation (n = 31) within 48 hours from preparation using a bimanual pull-through technique. MAIN OUTCOME MEASURES: Preparation and surgical times, intraoperative and postoperative complications, best spectacle-corrected visual acuity (BSCVA), endothelial cell density (ECD), and graft detachment rate. RESULTS: Preparation time averaged 26.2 ± 4.1 minutes (range 17-36 minutes), while the surgical time from opening of the stoppers to air fill of the anterior chamber never exceeded 9 minutes (range 3-9 minutes). Surgery was uneventful in all cases. Postoperative complications included graft detachment in 9 of 46 cases (19.6%), successfully managed in all cases by single rebubbling within 6 days from surgery, and glaucoma irresponsive to conservative treatment in 1 of 46 cases (2.1%). In all eyes without comorbidities (35 of 40 eyes) BSCVA was 20/25 (0.097 logMAR) or better as early as 3 months after surgery. Six months postoperatively, ECD was available in 24 of 25 eyes with an endothelial cell loss calculated as a percentage of the preoperative value determined at the eye bank (ranging from 2500 to 2800 cells/mm2) of 29.5% ± 14.8% (range 8.3%-52.1%). CONCLUSIONS: Delivering a preloaded DMEK tissue, tri-folded with the endothelium inwards, minimizes surgical time and costs without negatively affecting the outcomes of the procedure.

Granulometric analysis of corneal endothelium specular images by using a germ-grain model.

Specular microscopy is widely used to study the human corneal endothelium status in vivo. In this paper, the corneal endothelium is represented as a binary image composed of the cell inscribed circles. The granulometric distribution function of the complement of this image is used as a functional descriptor, which provides information about the shape, size and spatial arrangement of cells. Experimental evaluation using bootstrap techniques shows its ability to discriminate between controls and pathological cases. It represents a reliable and graphical alternative to the classical indices (cell density, hexagonality and coefficient of variation of cell areas), which behave poorly when detecting subtle abnormalities.

Morphological description of limbal epithelium: searching for stem cells crypts in the dog, cat, pig, cow, sheep and horse.

The cornea provides protection and transparency to the eye, allowing an optimal sharpness view. In some pathological conditions the cornea is able to regenerate thanks to the presence of a stem cells reservoir present at the level of the transition area between cornea and sclera (limbus). Corneal cell therapies in Veterinary Medicine are really limited due to the lacking of knowledge about the anatomy of the limbal area, the putative presence of stem cells and their identification in domestic species. The aim of this study was to provide an overview of the main distinctive structural features of the sclero-corneal junction and conjunctival-corneal junction areas in some species of veterinary importance, using optic microscope observations of histological sections. The resulting data were compared with cornea from humans adapting protocols already used to identify stem cells by means of a specific cellular marker. We tested the expression of ΔNp63α isoform in the cornea basal cells, trying to correlate the distribution profile with areas of highly proliferative turnover. The results obtained from this study represent a first step towards the identification of a corneal stem cells reservoir in different animals.

In Vivo Measurement of Human Corneal Impedance Value.

PURPOSE: To examine the validity of in vivo electrical corneal resistance (CR) measurements taken by a corneal resistance device (CRD). METHODS: Eighty-two eyes (mean age ± SD, 50.1 ± 23.3; range, 22-87 years: 50 eyes of 33 males and 32 eyes of 17 females) of patients who had undergone cataract surgery and volunteers at the Kanazawa Medical University Hospital were enrolled. The CR was compared among gender; age; side, that is, left versus right eye; healthy (fluorescein-negative) versus epithelium-injured eyes (fluorescein-positive), corneal radius of curvature; corneal endothelial cell count; and corneal thickness. RESULTS: The mean ± SD of the CR in the 82 eyes was 273.2 ± 78.2 Ω. By age group, the mean ± SD CR was 283.3 ± 87.4 Ω (30 eyes) in the 20s, 275.0 ± 50.0 Ω (4 eyes) in the 30s, 266.7 ± 70.7 Ω (9 eyes) in the 40s, 257.1 ± 53.5 Ω (7 eyes) in the 50s, 242.9 ± 78.7 Ω (7 eyes) in the 60s, 266.7 ± 84.0 Ω (18 eyes) in the 70s, and 300.0 ± 81.6 Ω (7 eyes) in the 80s, with no significant difference among the groups. By gender, the mean ± SD CR was 270.0 ± 83.0 Ω (50 eyes) in males and 278.0 ± 71.0 Ω (32 eyes) in females. By side, the CR values were 282.9 ± 83.4 Ω (44 eyes) in the right eye, 265.9 ± 71.3 Ω (41 eyes) in the left eye, with no significant difference among the groups. By status, the values were 280.0 ± 70.0 Ω (44 eyes) in healthy eyes and 200.0 ± 144.2 Ω (13 eyes) in injured eyes, with a significant between-group difference (P = 0.009). The mean ± SD corneal thickness (0.56 ± 0.03 mm) in 46 healthy eyes was slightly correlated with the CR. CONCLUSIONS: The CRD quantitatively measured the CR in healthy eyes. The CR did not differ significantly by age, gender, or left versus right eye. The significant difference in CR between the healthy and injured eyes showed that the measurements have validity.