Objective: To investigate the reproducibility and repeatability of anterior segment optical coherence tomography (AS-OCT) for measuring the tear meniscus height (TMH) and to evaluate its clinical application in the diagnosis of dry eye diseases.
Methods: Evaluation of diagnostic test. The inferior tear meniscus height of 36 eyes of 36 patients with dry eyes and 38 eyes of 38 normal volunteers were measured by AS-OCT and slit lamp marker lens in Zhongshan Ophthalmic Center, Sun Yat-sen University from November 2007 to August 2008. Then the paired t test, intra-class correlation coefficiency test, ANOVA and Spearman test were used for comparing TMH values between normal subjects and dry eye patients, two different examiners, two analysts, the repeated examines within a week, and AS-OCT group and slit lamp reticle lens group.
Results: There are no significant differences between different observers for the same 22 subjects [t = 1.881, P = 0.074; TMH: (0.256 +/- 0.052) mm and (0.265 +/- 0.066) mm], the same observer in different check-points for 20 subjects [ t = 1.306, P = 0.207; TMH: (0.265 +/- 0.056) mm and (0.272 +/- 0.052) mm] as well as different analyzers for the same 20 AS-OCT pictures [t = 2.048, P = 0.065; TMH: (0.266 +/- 0.059) mm and (0.259 +/- 0.062) mm]. There is a positive correlation between AS-OCT and reticule reading in measuring TMH (r = 0.713, P = 0.000); there are significant differences between normal subjects and patients with dry eye (t = 9.368, P = 0.000), and between groups of dry eye at different degree (F = 55.763, P = 0.000) [TMH: grade II, (0.228 +/- 0.036) mm; grade III, (0.145 +/- 0.056) mm; and grade IV, (0.084 +/- 0.048) mm]. The sensitivity and specificity of TMH value with AS-OCT for dry eye diagnosis was 77.8% and 71.7% when the diagnostic value was set to be 0.213 mm under the instruction of receptor operating characteristics curve (ROC).
Conclusion: AS-OCT has excellent reproducibility and repeatability for measuring the inferior tear meniscus height, and can be taken as an objective clinical imaging method for the diagnosis of aqueous deficiency dry eye.