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Mathew Margolis, Gary Holland, Joseph Caprioli, Fei Yu, Simon Law, JoAnn Giaconi, Anthony Aldave; Corneal Endothelial Cell Changes In Children with Uveitis and Ahmed Valves. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3669.
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To determine whether Ahmed valves (AV) are associated with corneal endothelial cell changes in children with non-infectious chronic anterior uveitis (CAU); and to investigate possible risk factors for such changes.
In a cross-sectional study, we evaluated patients with unilateral or bilateral CAU (onset of uveitis, age ≤16 years) who had undergone AV implantation in one or both eyes for control of uveitic glaucoma. Non-contact specular microscopy was used to measure the following variables associated with the corneal endothelium: central cell density (CCD); percent hexagonality; and coefficient of variation (CV). Central corneal thickness was measured by ultrasound pachymetry. The following potential risk factors for endothelial changes were determined by slit lamp biomicroscopy: total intraocular length of tube; length of tube segment in contact with clear cornea at its entry site (“tube touch”); separation of tube tip from the endothelium (≤1 corneal thickness vs. >1 corneal thickness). Interval since AV implantation was collected from medical records as an additional potential risk factor. Relationships were evaluated with the Kruskal-Wallis test and Spearman correlation coefficients. Results were adjusted for correlation between eyes in patients with bilateral uveitis using mixed effect models.
We evaluated a total of 46 eyes of 23 patients. After excluding 4 eyes of 3 patients that underwent prior cataract surgery, and 9 eyes of 9 patients without uveitis, 33 eyes of 20 patients (25 with uveitis and AV; 8 with uveitis and no AV) were included for analysis. Mean CCD was 2347.4±755.3 cells/mm2 for eyes with uveitis and AV, and was 2997.3±134.0 cells/mm2 for eyes with uveitis and no AV (p=0.05). There was no significant difference in percent hexagonality or CV between groups. Mean CCD was significantly lower in eyes with increased tube touch (r = -0.46, p=0.03), and increasing interval post AV implantation (r = -0.67, p=0.02). Lower CCD was associated with AV tubes closer to the endothelium (unadjusted p<0.01). There was no significant difference in central corneal thickness between groups.
Although causal relationships cannot be established in cross-sectional studies, our results suggest that corneal endothelial cell damage results from mechanical trauma and may progress over time. Despite endothelial changes, function, as indicated by corneal thickness, remains normal in most eyes.
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