Central Corneal Endothelium Research Articles

Automated digital image analysis of organ culture preserved donor corneas.

The present study reports the application of a modified commercially available automated digital image analysis system (DIA) for the evaluation of organ culture preserved donor corneas. The central corneal endothelium was viewed and photographed under an inverted phase-contrast microscope. The images were then analyzed with the help of DIA. The results of DIA were compared to the findings obtained with a conventional 'fixed-frame analysis' for the same corneas. 100 human donor corneas have been evaluated. DIA, with interactive picture enhancement, was found to be practicable, and to yield reproducible results. The mean number of cells analyzed per photograph was 250 (range 95-395); this, on the average, was four times higher than with conventional fixed-frame analysis (mean 54, range 37-70). The correlation of the cell densities obtained with both methods was highly significant (p < 0.0001). Since additional information, like variation in cell size and shape (circularity form factor), was automatically computed by the program, more data on the homogeneity of the donor endothelial cell pattern were available. Furthermore, this computerized technique does not require an experienced investigator and thereby helps to eliminate bias.

Quantitative Evaluation of the Effects of a Bicarbonate and Glucose-Free Balanced Salt Solution on Rabbit Corneal Endothelium in Vitro

Whole corneas from 2- to 2.5-kg albino rabbits were perfused in vitro at 35 to 36 degrees C with a commercial balanced salt solution (BSS) that lacks bicarbonate and glucose. The corneas swelled at an average rate of 45 +/- 11 microns/h. Evaluation of the corneal endothelium by scanning electron microscopy revealed no obvious cytotoxic effect beyond the occasional small area affected by air bubble damage. Morphometric analysis of the central corneal endothelium revealed no significant differences between the endothelial mosaic of perfused corneas, when compared to freshly fixed corneas, in terms of percentage 6-sided cells (pleomorphism) and variance in cell areas (polymegethism). In this example, therefore, a corneal swelling induced by a bicarbonate and glucose-free BSS does not appear to be due to either obvious endothelial cytotoxic effects or significant morphological alteration of the endothelial mosaic.

Changes in the Corneal Endothelial Cell Density and Corneal Thickness Following Intraocular Lens Implantation

The central corneal thickness and the central corneal endothelium of a consecutive group of 60 patients was measured before intracapsular (ICCE) and extracapsular (ECCE) surgery with implantation of an anterior (32 patients) or posterior (28 patients) chamber lens. The same measurements were made at 10 days and 1, 3 and 6 months after surgery. The mean increase in corneal thickness after surgery was found to be 36.8 μm at 10 days and 25.5 μm at 6 months in the first group of patients. In the second group, 49.5 μm and 29.0 μm. The mean endothelial cell loss after surgery was 21.9% at 1 month and 26.6% at 6 months in the first group of patients and 19.6 and 23.8% in the second group. A significant correlation between increase in corneal thickness at 10 days and percentage of endothelial cell loss at 6 months was only found in the second group of patients (r = 0.52, P = 0.01).

Long-term changes of the corneal endothelium following intracapsular cataract extraction with implantation of open-loop anterior chamber lenses.

The central corneal endothelium of a consecutive group of 158 patients with senile cataract was examined before intracapsular cataract extraction with implantation of an open-loop anterior chamber lens and 6, 12 and 48 months after surgery. Corneal endothelial morphometry was performed using an automated digital image analysis system. After 6 months of follow-up, there was an average loss of 10.8% in central corneal endothelial cell density, which increased to 14.8% after 12 months and 18.8% after 48 months. The early post-operative endothelial cell loss was correlated significantly with a decrease of cell pattern stability and polymegathism (P less than 0.0001). There was also a significant correlation between the continuous post-operative cell loss and the simultaneous changes of pattern stability and polymegathism and the age at the time of surgery (P less than 0.05).

Changes in corneal endothelial morphology in cats as a function of age.

A cross-sectional study of changes in cat corneal endothelial cell morphology with age was conducted. The central corneal endothelium of 12 kittens and 70 adult cats was photographed using specular microscopy. Endothelial cell density (ECD), coefficient of variation of cell size (used as an index of polymegethism), and cellular shape factor (perimeter 2/area) were determined for each animal and analysed as a function of age. We found a rapid non-linear decrease in ECD and polymegethism in the first nine months of post-natal life. Subsequently there was a slight central cell loss of 11 cells/mm2 or 0.37% per year during adult life which was not statistically significant. However, polymegethism increased significantly with age during adult life. The shape factor for endothelial cells was 13.61 throughout adult life, indicating that the cat corneal endothelium consists predominantly of six-sided cells. Possible explanations for the finding of no significant decrease in cell density with age could include the higher peripheral ECD in the cat which may compensate for central loss, the short life expectancy of the cat and the large individual variation in corneal diameter.

Corneal Endothelial Changes after Argon Laser Iridotomy

We used a continuous-wave argon laser to produce iridotomies in 28 eyes of 17 patients (12 women and five men ranging in age from 44 to 84 years) with angle-closure glaucoma. We photographed the central corneal endothelium with a contact specular microscope before and after the laser iridotomy was produced. The mean number of cells before treatment was 2,516 cells/mm2 and the mean number after treatment was 2,391 cells/mm2. The mean decrease, therefore, was 125 cells/mm2. This decrease was not statistically significant (P = .09). Retrogression analysis failed to show a correlation between the amount of energy necessary to produce the iridotomy and a decrease in endothelial cell density. Retrogression analysis also failed to show a correlation between the change in endothelial cell density and the time between the laser iridotomy and the performance of postoperative specular microscopy (one to 41 weeks).

Effects of Topical Timolol on Corneal Endothelial Cell Morphology In Vivo

To determine the effect of topical timolol on corneal endothelial cell morphology in a randomized, controlled, double-masked study of 40 healthy human eyes, we photographed the central corneal endothelium with a contact specular microscope before and after two weeks of treatment with placebo (20 eyes), with 0.5% timolol with 0.01% benzalkonium chloride (ten eyes), or with 0.5% timolol without benzalkonium chloride (ten eyes). From the specular photomicrographs, we analyzed five morphologic cell characteristics by means of electronic digitizer and microcomputer--cell density, mean cell area, the coefficient of variation for cell area, mean cell perimeter and a new feature quantifying cell shape. Statistical analysis of the data showed that two weeks of exposure to topical timolol or its preservative had no significant effect on corneal endothelial cell morphology in young, healthy eyes in vivo.

Regenerative effects of epidermal growth factor after penetrating keratoplasty in primates.

Epidermal growth factor (EGF) was injected into the anterior chambers of 12 rhesus monkeys after the denudation of the central corneal endothelium during autograft transplantation. The animals were treated both at the time of surgery and three weeks after surgery. Clinical appearance and corneal thickness were monitored until the corneas were removed by penetrating keratoplasty ten weeks after the initial treatment. Flat preparations of the corneas showed significantly more endothelial cells in the central corneas of the EGF-treated eyes compared with the control eyes. These findings indicate that EGF is effective in replenishing the corneal endothelium after injury.

Expression of HLA-A/B/C and -DR Locus Antigens on Epithelial, Stromal, and Endothelial Cells of the Human Cornea

ABSTRACT We studied class I (A/B/C) and class II (DR) HLA antigens on human corneal cells with monoclonal antibodies using immunofluorescence and immunoperoxidase techniques. Cryostat sections of freshly harvested human corneas expressed class I HLA antigens on the corneal epithelium. Class II antigens were not detected on these corneal specimens, except for occasional, scattered positive cells in the peripheral corneal epithelium and stroma near the corneoscleral limbus. Corneal endothelial whole flat mounts from freshly excised human corneas were negative for class I and class II HLA antigens. In tissue culture, however, growing human corneal endothelial cells expressed class I HLA antigens. Crowing human corneal fibroblasts in tissue culture similarly were shown, through immunofluorescent techniques using monoclonal antibodies, to express class I HLA antigens. Fibroblasts and endothelial cells in tissue culture were negative for class II HLA antigens. We believe the low-to-nondetectable HLA antigen expression on central corneal stroma and endothelium may partly explain the immunological tolerance enjoyed by most corneal allografts.

Corneal trauma in intracapsular and extracapsular cataract extraction with lens implantation.

We examined the central corneal endothelium before and eight weeks after cataract extraction and lens implantation in 99 consecutive intracapsular and extracapsular extractions each. There was no statistically significant different between the mean endothelial cell loss of 17.1% in the intracapsular group and 13.6% in the extracapsular group. The variation in individual endothelial cell sizes was less postoperatively in the extracapsular extractions. The central corneal thickness were the same in the two groups. There was no statistically significant difference between the mean endothelial cell loss of 17.0% in 24 posterior chamber lenses and 12.1% in 69 transiridectomy clip lenses, both with extracapsular cataract extraction. When combined with intraocular lens implantation, extracapsular cataract extraction, even when performed by surgeons inexperienced with extracapsular techniques, caused no greater corneal endothelial damage than intracapsular extraction.

Effect of blunt trauma on the corneal endothelium.

Specular microscopy of central corneal endothelium was performed on 26 patients with a history of blunt uniocular trauma with hyphema. Compared with the uninjured fellow eye, the injured eye had a mean decrease in endothelial cell density (ECD) of 6.4%. In 12 patients with angle recession, the decrease in ECD was 12.2%, compared with 14 patients without angle recession with a decrease in ECD of 1.2%. In five patients with greater than 180 degrees of angle recession, the mean decrease in ECD was 21.2%. No significant decrease in ECD was noted to be associated with size of hyphema, iridodialysis, vitreoretinal abnormalities, or transiently increased intraocular pressure.

The endothelial cell density after cataract surgery in young patients.

The central corneal endothelium was photographed with a specular microscope in 14 patients in the age range 7 to 31 years, who, at the age of 3 to 22 years, had been cataract operated due to a congenital cataract. Mean endothelial cell density (+/- SD) of operated (n = 20) and unoperated (n = 8) eyes was 2479 (+/- 490) and 3140 (+/- 188) cells/mm(2), respectively (P less than 0.01). It is concluded that, like in older patients, healing of the endothelial layer in young patients does not involve cell proliferation to the extent of complete restoration of the cell density. The significance of these findings is discussed.

Cataract Extraction and the Corneal Endothelium

We examined and photographed the central corneal endothelium of 16 patients with the clinical specular microscope before and at intervals after cataract extraction. No detectable loss of the endothelial cells occurred in 75% of the patients, including 12 routine intracapsular cryoextractions and four phacoemulsifications of soft cataracts in young adults. Only one of the four cases of significant endothelial cell loss occurred in a normal cornea without demonstrable operative or postoperative complications. Two of the four corneas that lost central endothelial cells at cataract extraction continued to lose more cells during the ensuing weeks. A significant increase in central endothelial cell density was demonstrated in one patient. The four corneas with endothelial cell loss also had a significantly higher mean increase in corneal thickness postoperatively, although this was transient. All 16 corneas remained clear during the period of observation (maximum, 14 weeks), and long-term studies are needed to measure the chronic effects of the endothelial damage.