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The authors present an up-to-date review of stromal hydration of the cornea and its controlling mechanisms. Stromal hydration quantifies the water component of the stroma. Its regularization depends on different factors which were detailed as; swelling pressure, corneal endothelial and epithelial metabolic pumps and barriers, tear film evaporation and intraocular pressure. Finally, the authors present different clinical procedures for evaluating stromal hydration, such as, the fluorophotometry and hypoxic-stress. This study shows the importance of stromal physiology and the consequences of all surgical or pathological modifications.

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Organ culture becomes a standard method of corneal graft preservation. The aim of the study was to evaluate the preservation injuries induced by organ culture. We examined 12 organ cultured human corneas. Corneas were preserved in the medium for 2 to 21 days. Corneas showed some abnormalities: numerous light vacuoles, mitochondrial swelling and increased cell thickness in all cells of the cornea, sloughing of the external and medium epithelial cell layers. We observed normal endoplasmic reticulum, Golgi apparatus and nucleus. These preservation injuries are moderate and reversible.

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The authors report a retrospective study of R.K. surgery performed on 72 eyes for simple myopia by one surgeon, five years after surgery. Fifty-four cases were observed regularly at 1 year and 5 years post-operatively, which allowed an analysis of refractive and visual parameters, for myopias between-1.5 and 6 D before surgery. Five years after: 92.9% of eyes were within +/- 1 D of emmetropia; 5.7% of eyes were undercorrected by more than 1 D; 1.4% of eyes were overcorrected by more than 1 D and 88.7% of the cases had uncorrected visual acuity of 20/40 or more. In general, our refractive and keratometric results were stable between the first and fifth year post-operatively. We report only one case of real undercorrection, and one case of progressive hyperopia with loss of best spectacle corrected visual acuity. In this study, we observed a statistically significant decrease of 1/100 in the mean uncorrected visual acuity, which is explained by remyopisations. All but one of them were less than 1 D. The review of long term results of R.K. is difficult because of the many different methodologies and protocols. However all of them show a unpredictable continuous increase in the effect of surgery in the hyperopia direction. Prolonged wound healing seems to be the most probable reason for this progressive hyperopia.

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The aim of this study was to examine the histology of a freshly removed kerato-lens lenticule (for keratoconus). The lenticule was obtained one year after refractive keratoplasty. It was removed by penetrating keratoplasty. The histological and transmission electron microscopic studies were performed.

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We conducted a prospective study of the corneal endothelium of 31 severely myopic eyes (17 patients) corrected by phakic anterior chamber intraocular lens. Patients were examined 3 months, 6 months and 12 months after surgical operation. In the center of the cornea, we noted a mean cell loss of 5.3% (p = 0.03) at 3 months, 8.2% (p less than 0.001) at 6 months and 15.5% at 12 months. The maximal cell loss was 21.6% at 3 months, 29% at 6 months and 58% at 12 months. The loss between 6 and 12 months was significant (p 0.01). In the periphery, the endothelial density was slightly lower than the central density (mean: 3.2%). In some cases, we saw areas of cellular denuding. It appeared that endothelial cell loss can be very different in the two eyes of the same patient, as well as between two different patients. Our study showed that the reduction of endothelial cell density was progressive with time. Intermittent contact between the implant and corneal endothelium was highly suspected, but this mechanism may not be the only one involved. The future integrity of these corneas is at stake and the problem of explantation of some implants is beginning to be a real one.

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In a series of 719 patients who underwent radial kératotomies, the authors report the results of pericentral deepenings 1 month and 1 year postoperatively because of undercorrection postoperatively. The improvement of residual myopia was 68.6% in the first group and 64.8% in the second group. There was no statistically difference between these two results. The dioptric improvement did not exceed 1.5 dioptre in all cases.

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In our daily clinical practice, keratomycosis still remain a challenge for both the ophthalmologist and the laboratory. In this paper simple advices are listed to help us, especially in the topical medical treatment. The emerging role of silver sulfadiazine is pointed out.

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The HLA antigens appear to be involved in the rejection of corneal allografts. A relationship exist between HLA compatibility and the corneal rejection-free transplant survival. Eleven corneal transplants are performed on the basis of the best available HLA A and B match. Rejection-free transplant in this group is compared to a control group. The estimate rejection-free survival is 82%.

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Using organ-culture preservation human corneas were preserved up to 5 weeks in a modified tissue culture medium at 37 degrees C. The endothelial viability was examined after staining with trypan-blue 0.3%, after determination of endothelial cell density and cell loss and by light microscopy after staining with trypan-blue 0.3% and alizarin red 1%. The biochemical analysis of the medium (pH, glucose, lactate) has allowed the evaluation of three kinds of storage. The influence of time preservation on the endothelial viability and the metabolic conditions are determined. At the end of this study a clinical trial is proposed.

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This study reports donor corneas stored at +37 degrees C in organ culture incubation. The follow up is 12 months. The graft survival is 92%. Two grafts are failed before 6 months. The mean control thickness is 0.54 mm and the mean endothelial cell density 1625 cells per mm2. A mean decrease in cell density of 40.6% is recorded. This study demonstrates that banked donor material can be successfully employed for corneal transplantation.

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Fresh human corneas and corneal buttons were studied for expression of HLA antigens. Using monoclonal antibodies in an indirect immunofluorescence assay, corneal layers were examined for class I (HLA-A, B, C) and class II (HLA-DR) histocompatibility antigens. Twenty-one human corneas were studied, 6 normal and 15 pathological: 4 buttons of allograft rejection, 9 buttons of pseudophakic bullous keratopathy. In fresh control corneas, HLA-A, B, C antigens were localized on corneal epithelium and on stromal keratocytes but were never found on endothelial cells. HLA-DR antigens were not detected on corneal epithelium, stroma or endothelium but were detected on Langerhans cells within epithelium and anterior stroma. At the corneal limbus, HLA class I-II antigens were expressed on vascular endothelium. HLA antigen distribution was modified in pathological corneas. Antigens HLA-A, B, C were induced on endothelial cells of rejected corneal allografts. Antigens HLA-DR were detected on epithelial cells, cells in the stroma of pseudophakic bullous keratopathy and also on endothelial cells of rejected corneal allografts. These results suggest that induction of class I and II antigen expression by inflammatory factors may occur in vivo. In rejected corneal allografts induction of HLA-DR antigen on corneal layers would intensify the process of rejection. This study and others have demonstrated the ability of modulation of HLA antigen expression on human corneal cells in vivo.

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The aim of this study is to examine the variation of HLA expression on organ-cultured human corneas. Using an indirect immunofluorescence technique and monoclonal antibodies anti-HLA-A, B, C and anti-HLA-DR histocompatibility antigens were detected. In fresh corneas class I antigens were detected on epithelium and stroma but not on endothelium. Class II antigens were not detected on any corneal layer but were present on Langerhans cells within epithelium and stroma. The expression of HLA-A, B, C antigens within the corneal epithelium and the corneal stroma was not altered by 28 days of organ culture. HLA-DR antigens were present on Langerhans cells on corneas that had been in organ culture up to 14 days (present 6/9). After 14-28 days in culture Langerhans cells were not found on most corneas (present 3/12). Corneal preservation in organ culture at 31 degrees C affects expression of HLA antigens particularly of HLA-DR antigens. Combination of HLA matching donor-recipient with an 10-15 days organ cultured corneal button in high-risk patients seems to be of interest.

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This study reports the clinical use of donor corneas stored at +37 degrees C in organ culture medium. Twenty-five penetrating keratoplasties were performed. The mean storage time of organ-cultured donor corneas was 12.3 days (3-21). The follow up of the patients was 12 months. The criteria for the survival of corneal grafts was mean central corneal thickness, clarity of the cornea and mean endothelial cell density. The graft survival was 92% at 12 months. The mean central corneal thicken was 0.54 mm. The mean endothelial cell density was 1625 cells/mm2. The mean decrease in endothelial cell density at 12 months was 40.6%.

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A study of 36 penetrating keratoplasties using donor corneas stored at +37 degrees C in organ culture incubation for an average of 12 days prior to transplantation is reported. The criteria for the survival of corneal grafts were mean central corneal thickness, clarity of the cornea and mean endothelial cell density. A total of 86% of the grafts remained clear after 12 months follow-up time. The mean central corneal thickness was 0.47 mm. The mean endothelial cell density was 1452 cells/mm2. Based on the results of this study, organ culture reported here appears to be a safe and efficient method of medium to long-term corneal storage.

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A corneal endothelium staining technique is described which can be performed in a few minutes. The first step of this in vitro staining is atraumatic for the endothelium. The cell density and the number of dead cells are thus determined. The second step is a staining of nuclear and intercellular spaces with a fixation by ethanol. Which then permits an histological analysis. This method of the endothelium, as described, thus allows for the control of corneal button either before grafts or after preservation, as well as the analysis of corneal pathologies.

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