Comparison of 24-2 and 24-2C Visual Field Testing in Eyes with Ocular Hypertension

Background and Objectives: Ocular hypertension (OHT) is associated with a variable risk of progression to primary open-angle glaucoma, and early detection of functional abnormalities is important during follow-up. The 24-2C visual field pattern was designed to improve central sampling by adding 10 test locations to the conventional 24-2 grid. This study aimed to compare central visual field findings obtained with the 24-2 and 24-2C protocols in patients with OHT. Materials and Methods: This prospective, single-center, paired comparative study included 60 eyes of 60 patients with OHT. Each eye underwent 24-2 and 24-2C testing using the SITA Faster strategy during the same visit, with randomized test order. Global indices, test duration, the number of abnormal points within the central 10°, central mean sensitivity, and the presence of abnormal central clusters were compared between protocols. Peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (mGCC) thicknesses were measured using spectral-domain optical coherence tomography, and structure-function relationships were explored. Results: Mean deviation, pattern standard deviation, visual field index, false-positive rate, and central mean sensitivity did not differ significantly between protocols. Test duration was longer with 24-2C than with 24-2 (167.4 ± 39.2 vs. 141.6 ± 31.9 s; p < 0.001). The number of abnormal points at p < 0.05 within the central 10° was higher with 24-2C (3.81 ± 3.6 vs. 2.35 ± 2.4; p = 0.006). Abnormal central clusters were detected in 19 eyes (31.7%) with 24-2C and 9 eyes (15.0%) with 24-2 (p = 0.031). Among eyes classified as normal on 24-2, 14 of 51 (27.5%) showed a central cluster on 24-2C. No significant correlations were found between central functional parameters and average RNFL or mGCC thicknesses. Conclusions: 24-2C detected more central abnormalities than 24-2 in eyes with OHT, while global visual field indices remained similar. Longitudinal studies are needed to establish the reproducibility and prognostic relevance of these additional findings.