Reliability of assessing the cup/disc ratio using a 90 D lens photograph

The reliability of estimating the cup to disc (C/D) ratio using a retinal camera photograph was compared to the same task using a photograph taken with the slit-lamp and +90 D lens. Twenty observers (10 optometry students, 10 faculty members) were asked to judge the C/D ratio of four eyes by the two photographic methods. When comparing the two clinically accepted photographic methods, statistically significant differences were noted for the vertical dimension estimate in two of four eyes. However, these differences were not clinically significant. C/D ratio estimates with the retinal camera photograph were typically larger than those of the slitlamp and +90 D lens photograph. Neither photographic method provided an advantage or disadvantage to clinicians with different levels of experience.