Abstract
Abstract: :
Purpose: To investigate the relation between corneal topographical patterns and ocular surface disease severity in patients with keratoconus Methods: Seventy-five eyes of 59 patients with keratoconus and 44 eyes of 22 healthy age and sex matched control subjects were enrolled in the study. All subjects underwent biomicroscopy, corneal topography , keratometry, pachymetry as well as ocular surface and tear function examinations including corneal sensitivity measurements, Schirmer test, tear film break up time, fluorescein and Rose-bengal ocular surface staining and conjunctival impression cytology. Rabinowitz criteria were used to diagnose keratoconus and CLAO criteria were employed to describe the severity of keratoconus. Mann-Whitney and Student-t tests were used for statistical analyses. Results: The mean corneal sensitivity, tear function, ocular surface staining and impression cytology( squamous metaplasia and goblet cell density) scores of the patients with keratoconus were significantly lower than those of the control subjects(p<0.001).Twenty-two eyes(%30) had central,27 eyes (%36) had inferocentral and 26 eyes (%34) had inferonasal or inferotemporal cones in corneal topography. All eyes with central cones had severe keratoconus according to CLAO guidelines.Patients with central cones had a higher frequency of reticular or midstromal scars, and Vogt striae. The mean corneal sensitivity in eyes with central cones was 50.5+0.5mm compared to 55+0.5 mm and 57.5+2.5mm in subjects with inferonasal/temporal and inferocentral cones respectively(p<0.001).The mean Rose Bengal ocular surface staining score was 4.12+0.58 points in patients with central cones compared to 2.05+1.12 in patients with inferocentral cones (p<0.001). The mean squamous metaplasia score in central cone patients was 2.07+0.5 compared to 1.58+0.21 and 1.35+0.15 in patients with inferocentral and inferonasal or temporal cones respectively(p<0.001).The mean goblet cell density in patients with central cones was 297+ 55 cells/mm2 which was significantly lower than the densities of the two other groups (p<0.001). Conclusions: Central corneal steepening in keratoconus was observed to be associated with significantly decreased corneal sensitivity, disturbed tear functions, keratinization of the ocular surface and lower goblet cell density. Central steepening reflected advanced stages whereas inferocentral, inferonasal or inferotemporal steepening reflected intermediate stages of keratoconus eye disease. Corneal topography provides useful information on the severity of the ocular surface disease in keratoconus.
Keywords: cornea: tears/tear film/dry eye • cytology • cornea: clinical science