Application of corneal topography in diagnosis of suspected keratoconus

Objective To investigate the specific sensitive indicators of corneal topography in patients with suspected keratoconus.Methods A contrast study of Orbscan-Ⅱ was performed on 18 cases(27 eyes)with suspected keratoconus and 23 cases(41 eyes)with subclinical keratoconus,which were selected from patients taking laser refractive surgery.Results Central corneal refractive power,difference of central corneal refractive power between both two eyes,Sim K value,difference of inferior-superior diopter,Diff value of anterior surface and posterior surface of cornea,3.0 mm Zone Irreg value and Astig Pwr value were(44.96±2.47)D,(1.86±1.17)D,43.45±5.31,(0.93±0.83)D,(0.017±0.021)mm,(0.039±0.021)mm,2.12±1.67 and 1.75±0.86 in patients with suspected keratoconus,and significant differences were found compared with those in patients with subclinical keratoconus(all P0.05).Corneal thinnest points were the most at inferior temporal quadrant(59.2%)in patients with suspected keratoconus and inferior nasal quadrant(56.1%)in patients with subclinical keratoconus.Conclusions Parameters of corneal topography was specific in patients with suspected keratoconus.The differences of parameters can provide an evidence for discriminating suspected keratoconus and subclinical keratoconus.