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Katrin Wacker, Jay W McLaren, Katrina Kane, Sanjay V Patel; Corneal endothelial function in Fuchs endothelial corneal dystrophy. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5287.
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© ARVO (1962-2015); The Authors (2016-present)
To assess corneal endothelial pump function in relation to severity of Fuchs endothelial corneal dystrophy (FECD) by measuring the percent recovery per hour (PRPH) of central corneal thickness after swelling the cornea. Associations between corneal morphologic parameters and PRPH were assessed to determine if these variables can predict endothelial function.
Twenty-one corneas of 21 phakic FECD patients and 7 corneas of 7 healthy controls devoid of guttae were examined by slit-lamp biomicroscopy. FECD severity was graded as mild, moderate, or advanced based on guttae area and confluence, and on the presence of edema (modified Krachmer scale). Effective endothelial cell density (ECDe) was determined from the area of guttae and local cell density in confocal microscopy images (ConfoScan 4). Steady state corneal thickness (CTss, measured mid-late afternoon), central corneal volume (over 3 mm-diameter), and corneal backscatter were measured from Scheimpflug images (Pentacam HR). Central backscatter from the anterior 120 μm and posterior 60 μm of the cornea was standardized to a fixed scatter source and expressed as scatter units (SU). Corneal swelling was induced by wearing a low-oxygen transmissible contact lens under a closed eyelid for two hours in the morning. De-swelling was measured over five hours after lens removal or until corneal thickness returned to CTss. PRPH was 100*(1 – e-k), where k was determined from CT(t)=d*e-kt + CTss by using regression models (d was the change from CTss with swelling; t was time in hours). Associations between morphologic parameters and PRPH were assessed.
Corneas swelled by 9% (95% CI, 8–10%) compared to CTss. Low PRPH was associated with high FECD grade (r=0.45, p= 0.022) and high corneal volume (r=0.38, p= 0.045). PRPH was 49%/h (95%CI, 40–58%/h) in controls and 37%/h in advanced FECD (95%CI, 29–45%/h, p=0.041). Corneas with ECDe <1000 cells/mm2 had a lower PRPH (36%/h; 95%CI, 29–43%/h) than corneas with ECDe >1000 cells/mm2 (47%/h; 95%CI, 41–52%/h; p = 0.019). Lower PRPH was associated with anterior (r=0.38, p=0.048) and posterior (r=0.55, p=0.002) corneal scatter.
Corneal hydration control is reduced and recovery of central corneal edema is impaired as the severity of FECD progresses. Morphologic parameters such as ECDe, backscatter, and central corneal volume are associated with, but not predictive of, corneal endothelial function.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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