The Ability of Disc-to-Fovea Distance to Disc-Diameter Ratio to Estimate Optic Disc Size

Abstract

목적: 시신경유두직경에 대한 유두연-황반오목거리의 비(disc-to-fovea distance to disc-diameter ratio; DF/DD ratio)의 큰 시신경 유두와 작은 시신경유두 구별에 대한 유용성을 알아보았다.

대상과 방법: 정상 및 녹내장 300안을 대상으로 입체 시신경유두 사진을 이용하여 DF/DD ratio를 구하고, 시신경유두 크기에 대한 추정 능력 판정을 위해 Area under the receiver operating characteristics curves (AUCs)와 민감도 및 특이도를 분석했다.

결과: DF/DD ratio를 이용하여 예측한 AUCs는 큰 시신경유두의 경우 0.942, 작은 시신경유두의 경우 0.947이었다. DF/DD ratio 2.0을 기준으로 하였을 때 각각의 진단에 있어 100%의 민감도를 가지나 큰 시신경유두는 70.2%, 작은 시신경유두는 40.9%의 특이도를 보였다.

결론: DF/DD ratio는 큰 시신경유두와 작은 시신경유두의 구별에 유용하며 DF/DD ratio 2.0을 기준으로 설정하면 100%의 민감도를 보였으나 중간 크기의 시신경유두가 작은 시신경유두로 분류될 확률이 높았다.

Purpose: To investigate the usefulness of the measurement of disc-to-fovea distance to disc-diameter ratio (DF/DD ratio) in detecting large and small discs.

Methods: A total of 300 randomly selected subjects were included in the present study. All patients underwent stereoscopic disc photography and DF/DD ratio, which is the shortest distance between disc margin and fovea divided by mean disc diameter was determined by planimetry. The diagnostic accuracy of DF/DD ratio was evaluated using areas under the receiver operating characteristics curves (AUCs), sensitivity, and specificity.

Results: No significant differences in disc-to-fovea distance were observed among small and large disc groups. The DF/DD ratio was significantly lower in subjects with large discs (1.74 ± 0.27) compared with subjects with small discs (2.70 ± 0.15). AUCs of the DF/DD ratio were 0.942 and 0.947 in detecting large and small discs, respectively. In detecting disc size by a fixed DF/DD ratio of 2.0, sensitivity was 100% for both large and small discs, and specificity was 70.1% and 40.9% for the large and small discs, respectively.

Conclusions: The DF/DD ratio may be a simple and useful clinical aid in detecting large and small discs. The 2.0 fixed DF/DD ratio, showed 100% sensitivity in detecting both large and small discs, although medium discs may be misdiagnosed as small discs more often than as large discs.