Abstract
Purpose :
Corneal dystrohies are regarded as corneal opacity diseases, and the decreased visual acuity is considered to be caused by decreased corneal clarity. To date the influence of anterior and posterior corneal surface disturbances on vision has been inadequately studied both in normal and dystrophic corneas. The purpose is to evaluate anterior and posterior corneal astigmatism, elevation maps, Fourier indices, thickness of the cornea, anterior chamber parameters in normal and Fuchs endothelial corneal dystrophy (FECD) eyes with the anterior eye segment swept source optical coherence tomography (SS OCT)
Methods :
This study was performed in accordance to the Declaration of Helsinki. 70 eyes of 70 normal subjects and 50 eyes diagnosed with FECD were included. Analyzed parameters included: anterior and posterior corneal astigmatism; flat and steep corneal power (Ks, Kf), cylinder axis, average keratometry (AvgK), average central corneal power (ACCP), mean, maximum 4mm central and peripheral anterior and posterior elevation (µm), 3, 6 mm Fourier indices (spherical, regular, asymmetry, higher-order),ectasia screening index, central corneal thickness, thinnest thickness (value, location), pupil diameter (mm), anterior chamber depth (ACD, mm)
Results :
There was no significant difference in mean K readings, mean astigmatism and mean ACCP between FECD and control eyes. Mean maximum posterior central and peripheral elevation was significantly higher compared to anterior elevation in both groups. There was a high degree of mirror symmetry in shape between the right and left corneas based on posterior elevation maps in normal eyes. A slightly elevated isthmus (mean +13 µm SD 4.67) joined the central cornea to the temporal periphery. In FECD there was no posterior elevation mirror symmetry with the greatest degree of irregularity. There was a significant difference in 3, 6 mm Fourier indices, corneal thickness, ACD (p<.01, p=.001, p<.001; p=.01respectively) and the thinnest point location
Conclusions :
The information on corneal posterior elevation mirror symmetry of normal eyes provides a reference data for comparison with diseased corneas. The corneal edema is the main well known feature of FECD, but the significant change in other corneal parameters – posterior elevation map and Fourier indices should be taken into consideration in the disease pathogenesis
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.