Abstract
Purpose:
In Fuchs endothelial corneal dystrophy (FECD), structural abnormalities of the anterior cornea, including a reduction in keratocyte density, have been found in corneas requiring keratoplasty. In this study, we examined the changes in keratocyte populations over a range of severity of Fuchs endothelial dystrophy.
Methods:
In a cross-sectional study, 62 corneas (39 patients) with FECD and 23 normal corneas (12 subjects) were examined. Clinical grade of FECD was determined by slit-lamp examination based on the presence and extent of guttae and edema (modified Krachmer grades 1-6). FECD was categorized as mild (grades 1-2), moderate (grades 3-4), or advanced (grades 5-6). Corneas of control subjects were devoid of any central guttae (grade 0). Corneas were examined by confocal microscopy (ConfoScan 4, Nidek Technologies), and keratocyte density and the number of keratocytes in a column with en face area of 1 mm2 were determined in 5 layers of stroma (anterior 10%, 11%-33%, 34-66%, 67-90%, and posterior 10%). Keratocytes were first identified by an automated program and then each confocal image was reexamined manually by one experienced observer (SVP). Keratocyte populations in each layer of stroma were compared between severities of FECD by using generalized estimating equation models to account for any correlation between fellow eyes of the same subject.
Results:
Keratocyte density within the most anterior 10% of the corneal stroma was lower in mild (17,611 ± 3,975 cells/mm3, mean ± SD, n=22, p<0.001), moderate (20,041 ± 5,945 cells/mm3, n=20, p<0.009), and advanced (19,478 ± 4,654 cells/mm3, n=20, p<0.001) FECD compared to controls (25,976 ± 6,394 cells/mm3). The number of keratocytes in the anterior 10% of the corneal stroma was also less in mild (882 ± 210 cells, p<0.001), moderate (981 ± 235 cells, p<0.001), and advanced (1,002 ± 232 cells, p <0.001) FECD compared to controls (1,341 ± 297 cells). There were no differences in cell density or number in deeper layers of the stroma.
Conclusions:
The decrease in anterior keratocytes in FECD is limited to the anterior 10% of the stroma, and begins early in the course of the disease, before the appearance of clinically evident corneal edema. Early structural changes in the anterior corneal stroma might be related to the early symptom of glare in FECD.
Keywords: 461 clinical (human) or epidemiologic studies: natural history •
481 cornea: endothelium •
484 cornea: stroma and keratocytes