Influence of ocular biometry on peripheral retinal visualization: a comparative study of Clarus and Optos widefield imaging systems

BACKGROUND: The purpose was to compare the Clarus 500 and Optos Daytona widefield imaging systems with respect to the farthest clinically assessable peripheral retinal structure in each quadrant, and to evaluate whether ocular biometry, particularly axial length and spherical equivalent, influences device specific widefield performance. METHODS: Twenty-six eyes underwent same day widefield imaging with Clarus 500 (Zeiss Meditec AG, Jena, Germany) and Optos Daytona (Optos plc, Dunfermline, UK). For each quadrant, the most peripheral anatomically interpretable structure was identified, and device differences were analyzed using McNemar tests. Associations with axial length and spherical equivalent, were evaluated using Mann-Whitney U tests and univariate and multivariate logistic regression. Receiver operating characteristic analysis was performed to assess the predictive value of axial length and to determine the optimal cutoff for device superiority. RESULTS: Both widefield systems showed similar performance in the superior temporal, inferior temporal, and inferior nasal quadrants with no statistically significant differences. In the superior nasal quadrant, however, eyes in which Clarus reached farther had significantly longer axial length (23.97 ± 1.62 mm versus 22.53 ± 0.94 mm, p = 0.016) and a more myopic spherical equivalent (- 2.05 ± 4.52 D versus + 2.69 ± 2.56 D, p = 0.019). Axial length significantly predicted cases in which Clarus reached farther into the periphery in univariate regression (odds ratio 2.39, p = 0.033). Receiver operating characteristic analysis demonstrated good discriminatory ability of axial length with an area under the curve of 0.782 and an optimal cutoff of 23.77 mm. Shorter and hyperopic eyes showed a tendency toward greater peripheral reach with Optos, although this trend did not achieve statistical significance. CONCLUSION: An axial length cutoff value of 23.77 mm was identified as a threshold for device-specific differences in peripheral retinal visualization. Device differences become apparent in the superior nasal quadrant, where axial elongation and myopic ocular geometry were associated with greater peripheral reach of the Clarus system, while no statistically supported advantage for Optos is observed in shorter or hyperopic eyes. Overall, the Clarus 500 and Optos Daytona provide comparable peripheral visualization in most retinal quadrants. These findings should be interpreted in the context of the exploratory study design.