Is Choroidal or Scleral Thickness Related to Myopic Macular Degeneration?

PURPOSE

The relative contribution of mechanical and vascular factors to the pathogenesis of myopic macular degeneration (MMD) is unclear. To address this gap, we examined the association of choroidal thickness (CT) and scleral thickness (ST) with MMD.

METHODS

Prospective, clinic-based case series of 62 eyes of 41 patients with high myopia (≤-6 diopters or axial length ≥26.5 mm). Swept-source optical coherence tomography (SSOCT) was performed to measure subfoveal CT and ST. Myopic macular degeneration was graded from fundus photographs according to the International Meta-Analysis for Pathologic Myopia (META-PM) classification. Presence of MMD was defined as META-PM category ≥ 2 and severe MMD was defined as category ≥ 3.

RESULTS

The distribution of MMD severity was 15 (24.2%) in category 1, 28 (45.2%) in category 2, 10 (16.1%) in category 3, and 9 (14.5%) in category 4. Correlation of MMD severity was strong for subfoveal CT (r = -0.70, P < 0.001) but weak for subfoveal ST (r = -0.31, P = 0.01). Subfoveal CT, but not ST, was independently associated with presence of MMD (age and gender adjusted odds ratio [OR] per 10 μm decrease in CT 1.41, P = 0.002), and subfoveal CT, but not subfoveal ST, was significantly thinner in eyes with severe MMD (≥ category 3) than in eyes with mild MMD (CT: 31.5 ± 40.5 μm versus 82.0 ± 57.1 μm, P < 0.001; ST: 261.6 ± 78.5 μm versus 297.0 ± 73.8 μm, P = 0.09).

CONCLUSIONS

We demonstrated significant thinning of the choroid with increasing MMD severity. In contrast, ST was weakly correlated with MMD. These data suggest progressive loss of choroid may be important in the pathogenesis of MMD.