Orbscan Ⅱ 각막지형도를 이용한 원추각막의 진단 기준 설정

Diagnostic Criteria for Keratoconus Using Orbscan Ⅱ Slit Scanning Topography/Pachymetry System

목적: Orbscan Ⅱ System을 사용하여 원추각막의 새로운 진단 기준을 마련하고자 하였다. 대상과 방법: 원추각막 환자 45명 80안과 무작위로 선정된 정상대조군 50명 100안에서 Orbscan Ⅱ를 시행하였고, Anterior elevation from BFS, Posterior elevation from BFS, Sim K (maximum), Thinnest pachymetric value에 대한 정상대조군의 2 표준편차 범위를 산출하여 원추각막 진단의 척도로 삼았다. 결과: Orbscan Ⅱ에서 얻을 수 있는 모든 척도에서 원추각막안과 정상대조안 사이에는 유의한 차이를 보였고 (p<0.001), Anterior elevation from BFS > 23.3 ㎛, Posterior elevation from BFS > 49.8 ㎛, Sim K (maximum)> 47.0D, Thinnest pachymety <455.0 ㎛ 중 3가지 이상을 만족할 경우 86.3%의 민감도와 99.0%의 특이도로, 2가지 이상을 만족할 경우 96.3%의 민감도와 특이도로 원추각막을 진단할 수 있다.

Purpose: To investigate new diagnostic criteria of keratoconus using Orbscan Ⅱ Slit Scanning Corneal Topography/Pachymetry Syestem. Methods: Eighty eyes of 45 patients with keratoconus and 100 randomly selected eyes of 50 patients without any ophthalmologic problem were enrolled in this study. Anterior elevation from BFS, posterior elevation from BFS, Sim K (maximum), and thinnest pachymetric value were evaluated using Orbscan Ⅱ. Values outside 2 standard deviations from the mean value of each parameter were estimated to the upper or lower limits in diagnosing keratoconus. Results: There were significant differences of all parameters of Orbscan Ⅱ between the keratoconic eyes and the control (p<0.001). Keratoconus could be diagnosed with 86.3% sensitivity and 99.0% specificity when 3 or more criteria were satisfied and with 96.3% sensitivity and 99.0% specificity when 2 or more criteria were satisfied out of the following 4 criteria; anterior elevation from BFS > 23.3 ㎛, posterior elevation from BFS > 49.8 ㎛, Sim K (maximum) > 47.0 D, thinnest pachymetric value < 455.0 ㎛. Conclusions: Orbscan Ⅱcan provide useful information in the diagnosis of keratoconus with high sensitivity and specificity.