Analysis Of Corneal Epithelial Thickness Of Forme Fruste Keratoconus With Optical Optical Coherence Tomography

Purpose:To explore the significance of corneal epithelial thickness analysis in diagnosing early keratoconus.Methods:Fourier-domain optical coherence tomography was used to measure the corneal epithelial thickness and corneal thickness of forme fruste keratoconus,clinical keratoconus,high corneal astigmatism and low corneal astigmatism eyes.Compared the morphological features of topographic map of the corneal epithelial thickness and corneal thickness.Analyzed the thickness of the thinnest point of corneal epithelium and cornea.The polar positions of the thinnest point of cornea were also analyzed.The distribution curve of corneal epithelial thickness and corneal thickness in 45°,90°,135°axial directions which are through the pupil center were also compared and analyzed.Results:The study comprises 26 eyes from 26 clinical keratoconus patients(20 male and 6 female),with a mean age of 23.81±7.16 years,21 eyes from 21 forme fruste keratoconus patients(17 male and 4 female),with a mean age of 22.33±7.39 years,40 high corneal astigmatism eyes of 40 subjects(24 male and 16 female),with a mean age of 20.15±6.34 years,and 40 low corneal astigmatism eyes of 40 subjects(20 male and 20 female),with a mean age of 23.13d±3.99 years.Corneal epithelial thickness topography can be divided into uniformity shape,crater shape,irregular shape and central island shape.Topographic maps of forme fruste keratoconus corneal epithelial thickness were all uniformity shape(100%);25 eyes crater shape(96.15%)and 1 eye irregular shape(3.85%)were in clinical keratoconus group.28 eyes uniformity shape(70.00%)and 12 eyes central island shape(30.00%)were in high corneal astigmatism group.37 eyes uniformity shape(92.50%)and 3 eyes central island shape(7.50%)were in low corneal astigmatism group.The thinnest point of corneal epithelial thickness of forme fruste keratoconus group was significantly lower than that of low corneal astigmatism group(P=0.022).The thickness of corneal epithelium in the forme fruste keratoconus at 90 degree was thinner than that in the low astigmatism group at-1mm,-2mm points(P-1mm=0.015,P-2mm=0.036).The cornea thickness of forme fruste keratoconus was thicker than that of the clinical keratoconus group.Compared with low corneal astigmatism group,cornea thickness of forme fruste keratoconus was thinner in central inferior temporal area.Conclusions:Characteristics of forme fruste keratoconus are the thinnest point of corneal epithelium thinning and uniformity shape in corneal epithelium topographic map.Corneal epithelial thickness,obtained by Fourier-domain optical coherence tomography,can be used in diagnosing early keratoconus.