Assessment of Macular Thickness in Myopic Patients and Its Correlation with Axial Length: A Hospital-Based Study

To evaluate macular thickness across different grades of myopia and examine its associations with axial length (AL) and spherical equivalent refraction (SER) using spectral-domain optical coherence tomography (SD-OCT).

This cross-sectional study included 170 myopic subjects aged 18-35 years, comprising 44 low myopes (SER ≤ -0.50 to > -3.00 D), 86 moderate myopes (≤ -3.00 to > -6.00 D) and 40 high myopes without pathological changes (≤ -6.00 D). AL was measured using partial coherence interferometry and full, inner and outer retinal thicknesses were obtained for foveal, parafoveal and perifoveal regions with SD-OCT. SER was measured using an autorefractometer. Pearson's correlation analysed associations between macular thickness, AL and SER.

The mean age was 24.6 ± 4.9 for low, 24.3 ± 4.9 for moderate and 25.0 ± 5.2 years for high myopia. Mean AL increased with myopia severity (low: 24.2 ± 0.9 mm; moderate: 24.8 ± 0.8 mm; high: 26.0 ± 0.9 mm; p < 0.001). Inner perifoveal thickness decreased with increasing myopia (low: 108.5 ± 6.9 µm; moderate: 107.2 ± 6.3 µm; high: 104.5 ± 6.8 µm; p = 0.02) and correlated negatively with AL (r = -0.34, p < 0.001) and SER (r = -0.33, p < 0.001) across all participants. Full perifoveal thickness also correlated with AL (r = -0.34, p < 0.001) and SER (r = -0.28, p < 0.001), whereas outer perifoveal thickness correlated only with AL (r = -0.26, p = 0.001). Other macular subfields, including the central fovea and remaining outer retinal layers, showed no significant associations across all participants.

Myopia is linked to localised thinning of the inner perifoveal retina, while central foveal and outer layers remain preserved, highlighting region-specific retinal changes and the importance of layer-specific OCT assessment for early detection.