Reference intervals for macular ganglion cell complex parameters using spectral-domain OCT in a healthy persian adult population: a cross-sectional study

To establish reference intervals (RIs) for macular ganglion cell complex (GCC) parameters measured by spectral-domain optical coherence tomography (SD-OCT) in a healthy adult population. In this cross-sectional study, healthy participants underwent macular SD-OCT imaging. Reference intervals for GCC-related parameters, including inner retinal thickness, full retinal thickness, outer retinal thickness, asymmetry indices, and loss metrics, were established in accordance with CLSI EP28-A3 guidelines. Reference intervals were calculated using non-parametric rank-based methods or robust parametric approaches with bootstrap-derived 95% confidence intervals. A total of 491 participants (mean age 40.62 ± 7.35 years; 218 females and 273 males) were included. Thickness-based GCC parameters demonstrated approximately symmetric distributions with low variability, whereas loss-based indices showed greater dispersion. Pooled reference intervals were appropriate for most GCC parameters. Sex-specific partitioning was required only for outer retinal thickness measures, with males demonstrating slightly higher values than females. Age-based partitioning was generally not required, although selective age dependence was observed for certain loss-related indices. The overall reference interval for inner retinal average thickness was 86.56–108.96 μm, and for outer retinal average thickness 161.68–192.66 μm. This study provides robust, CLSI-compliant reference intervals for GCC parameters measured by spectral-domain OCT in healthy adults. These normative data may serve as a reference framework for future studies investigating GCC alterations in glaucomatous and neuro-ophthalmic diseases and may contribute to the development of population-specific diagnostic and monitoring strategies.