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C.B. Nau, D.C. Herman, D.O. Hodge, J.W. McLaren, W.M. Bourne; Corneal Stromal Cell Density in Treated vs. Non–treated Patients of the Ocular Hypertension Treatment Study: Single Center Evaluation . Invest. Ophthalmol. Vis. Sci. 2004;45(13):3829.
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Purpose: In an earlier study we noted a decrease in corneal thickness in patients treated for ocular hypertension in the Ocular Hypertension Treatment Study (OHTS). In this study, we compared stromal cell density and reflectivity in the same groups of patients. Methods: Eighty eyes of 40 patients (of 58 patients originally enrolled) in the OHTS were examined by confocal microscopy at 84 to 108 months after beginning the study. Central corneas were scanned by using a tandem scanning confocal microscope (Tandem Scanning, Inc., Reston, VA). We estimated stromal reflectivity (average brightness of the image), stromal cell density, and corneal thickness from the digitized scans. We compared these variables between the 44 eyes of 22 patients randomized to the treatment group and the 36 eyes of 18 patients randomized to the observation group. Scans of several of the eyes were inadequate for measurement. Generalized Estimating Equation (GEE) models were used for satistical comparisons. Non–normal factors were evaluated by using rank transformations and tested with GEE models. Results: Reflectiviy was 103 ± 11 intensity units (mean ± SD, n=44) in the treatment group and 96 ± 9 intensity units (n=35) in the observation group (p=0.01). Cell density in the anterior 10% of the stroma was 23,123 ± 7,732 cells/mm3 (n=42) in the treatment group and 21,108 ± 7,052 cells/mm3 (n=34) in the observation group (p=0.37). Thickness–corrected mean cell density through the stroma was 17,366 ± 2,511 cells/mm3 in the treatment group and 16,504 ± 1,954 cells/mm3 in the observation group (p=0.17). Corneal thickness was less in the treatment group (532 ± 39 µm, n=44) than it was in the observation group (565 ± 31 µm, n=35; p<0.001). When we excluded the 15 eyes originally in the observation group in which treatment was initiated before confocal microscopy, the results were unchanged except for reflectivity, which was not significant (98 ± 11 intensity units, n=20, p=0.07). Conclusions: As we noted in an earlier paper, treatment of ocular hypertension reduces the thickness of the cornea. This thinning is accompanied by a small increase in reflectivity of the stroma, as measured by confocal microscopy, but is not accompanied by a change in stromal cell density.
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