Digital measurement of blepharoptosis using smartphone photography and built-in markup tools: A prospective, blinded methodological comparison study with traditional ruler-based assessment

To evaluate the accuracy, consistency, and efficiency of a novel digital measurement method for blepharoptosis grading utilizing iPhone photography and built-in markup tools, compared to the traditional ruler method. In this prospective, blinded methodological comparison study, 145 patients (185 eyes) with blepharoptosis were enrolled. Each patient underwent marginal reflex distance 1 (MRD1) measurement via both the traditional ruler method (control) and the iPhone method (experimental). The iPhone method involved capturing standardized photographs and performing measurements using the device's native markup feature. Agreement between methods was assessed using the Intraclass Correlation Coefficient (ICC) and Bland-Altman analysis. Grading consistency was evaluated using the Kappa statistic, and operational efficiency was compared via independent t-tests. The mean MRD1 values were 2.18 ± 0.94 mm (ruler) and 2.22 ± 0.89 mm (iPhone), with no statistically significant difference (P = .188). The 2 methods demonstrated excellent agreement, with an ICC of 0.968 (95% CI: 0.956-0.977). Bland-Altman analysis showed a mean bias of -0.04 mm, with 95% limits of agreement from -0.51 mm to 0.43 mm. Clinical grading consistency was almost perfect (Kappa = 0.892). The iPhone method was significantly more efficient, requiring less time than the traditional method (64.8 ± 18.7 s vs 86.5 ± 22.3 s, P < .001). The smartphone-based digital measurement method proves to be an accurate, reliable, and efficient alternative to the traditional ruler method for quantifying MRD1 and grading blepharoptosis. It demonstrates high agreement with conventional techniques while offering advantages in standardization, traceability, and operational workflow. This approach holds significant potential for enhancing diagnostic precision in clinical practice, particularly in outpatient and primary care settings.