Accuracy of the indices of MS-39 anterior segment optical coherence tomography in the diagnosis of keratoconic corneas

Purpose To determine the normative and the cut-off values of various indices available in the MS 39 Anterior Segment Optical Coherence Tomography (MS-39 AS-OCT) for keratoconus (KC) diagnosis, and to detect the accuracy of the variable available parameters. Methods This cross sectional observational study was conducted at Dr Rifay Ophthalmology Center, Rabat, Morocco, on 172 eyes with KC (group 1) and 248 eyes of healthy controls (group 2). Participants were screened using MS-39 AS-OCT (CSO, Firenze, Italy). The investigated indices included: keratometric indices, pachymetric indices, elevation indices, Keratoconus Summary Indices (KSI), aberration indices, and epithelial mapping evaluation. Results Most of the studied indices were significantly different between both groups (P value <0.001). Twenty two indices had Area Under the Receiver Operating Curve (AUROC) values >0.950, eight of which were from the KSI. The indices with the highest AUROC values were: Root Mean Square (RMS) for the front corneal surface at 6 mm circle (AUROC = 0.996, and best cut-off >1.69 with sensitivity of 97.67% and specificity of 97.98%) and RMS per unit of area for the front surface at 6 mm circle (AUROC = 0.996, and best cut-off >0.06 with sensitivity of 97.67% and specificity of 97.98%). Epithelial thickness-derived metrics were not among the parameters with the highest accuracy. Conclusions This study presented the mean and the cut-off values for a plethora of parameters available in the MS-39 AS-OCT. The results of this study show that MS-39 AS-OCT is a valuable equipment for diagnosing keratoconic corneas, with a high accuracy detected for many parameters.