Abstract
Purpose: :
To measure macular choroidal thickness (CT) using spectral domain optical coherence tomography (OCT) in eyes with myopic macular choroidal neovascularization (CNV), and to investigate whether the choroid is thinner in these eyes comparatively to highly myopic eyes without CNV.
Methods: :
A cross sectional study, performed between January and June 2010, included 42 eyes with myopic CNV matched with 42 highly myopic eyes without CNV according to age and spherical equivalent (SE) refractive error. OCT scans were performed with the spectral domain OCT (OCT TOPCON 2000) by changing the reference position from the vitreous to the choroid. OCT scan patterns consisted in 7 sections, the horizontal section going through the center of the fovea was used for CT measurements. Subfoveal CT was measured manually from the outer portion of the hyper-reflective line corresponding to the retinal pigment epithelium to the inner surface of the sclera. In eyes with CNV, the subfoveal CT was measured between the Bruch membrane, and the inner portion of the sclera.
Results: :
In the subgroup with CNV, the mean age was 51,5 years ± 14,8 years, the mean SE was -16,37 Diopters (D) ±4,1D, and the mean subfoveal CT was 51,71 µm ±17,35µm. No correlation was found between CT and age, and a significant negative correlation was found between CT and SE (r=-0,493, P=0,01). The regression equation implied a decrease of 2,1µm per D of myopia. In the subgroup without CNV, matched with the subgroup with CNV in age (P=0,945), and SE (P=0,965), the mean subfoveal CT was 93,35µm ±34,81µm. The comparison between the two subgroups found a statistically significant difference in subfoveal CT (P<10-3).
Conclusions: :
Choroidal thinning observed in high myopia is more important in eyes with myopic macular CNV. These findings suggest that abnormalities of the choroid may play a role in the pathogenesis of myopic degeneration and CNV.
Keywords: myopia • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • choroid: neovascularization