Optic nerve head analysis of superior segmental optic hypoplasia using Heidelberg retina tomography

PURPOSE To evaluate the optic disc characteristics of eyes with superior segmental optic hypoplasia (SSOH) using the Heidelberg retina tomograph (HRT). PATIENTS AND METHODS Thirteen eyes of 13 Japanese patients with SSOH were studied with the HRT (software version: 3.0). The group included six males and seven females, with a mean age of 34.7 years. Six optic disc parameters in the six sectors derived from the patients with SSOH were compared with those of 13 eyes of 13 normal controls. In addition, the diagnostic classification performance of the Frederick S Mikelberg (FSM) discriminant function, glaucoma probability score (GPS), and Moorfields regression analysis (MRA) were assessed. RESULTS When compared with normal subjects, many of the optic disc parameters were significantly altered in SSOH in the superior sectors. The area under the curve (AUC) for the receiver operating characteristic was 0.932 for the rim area, 0.926 for the cup-to-disc area ratio, and 0.882 for the cup shape measure. Among the HRT parameters, the largest AUC (0.988) was found for the cup shape measure in the nasal superior segment. The proportion classified as outside normal limits by the FSM discriminant function was 92.3% (12 eyes). For GPS, six eyes (46.2%) were classified as outside normal limits. For MRA, when borderline cases were considered test-negative or test-positive, 10 eyes (76.9%) or 11 eyes (84.6%) were classified as outside normal limits, respectively. The AUCs were 0.976 for the FSM discriminant function, 0.914 for the MRA overall classification, and 0.710 for the GPS overall classification. CONCLUSIONS In eyes with SSOH, there is a significant thinning of the rim, especially in the nasal superior sector. Approximately half of the eyes with SSOH were classified as abnormal using indices developed for detecting glaucoma, but the sectorial analysis revealed that the affected sectors were different from those of glaucoma. Optic nerve head measurements using the HRT may be useful in evaluating the optic disc characteristics in eyes with SSOH.