Retinal and choroidal biometry in highly myopic eyes with spectral-domain optical coherence tomography

Morphologic changes in the retina and choroid are closely related with high myopia-related diseases. This study was conducted to evaluate the morphologic characteristics of normal highly myopic eyes.

Thirty-one phakic highly myopic eyes with no posterior abnormalities (18 patients; mean +/- SD age, 51.7 +/- 11.4 years) were enrolled. Retinal-choroidal thickness at the fovea 1.5 mm superiorly, inferiorly, nasally, and temporally and the choroidal curvature were measured in the 512 x 128 three-dimensional scan mode with spectral-domain optical coherence tomography. The degree of posterior staphyloma was determined as the sum of the vertical distance from the retinal pigment epithelial line beneath the fovea to the nasal, temporal, superior, and inferior edge of the image, including the fovea. The association of clinical data with these parameters was evaluated.

The mean +/- SD central retinal thickness was 200.9 +/- 39.3 microm. The mean choroidal thickness at the fovea (100.5 +/- 56.9 microm) was significantly different from the temporal (125.4 +/- 59.7 microm), nasal (81.9 +/- 35.0 microm), and superior (129.4 +/- 57.5 microm) thicknesses (P < 0.01). Central retinal thickness did not correlate with age, sex, refractive error, axial length, or central choroidal thickness. Central choroidal thickness was significantly associated with refractive error (P < 0.05) and posterior staphyloma height (P < 0.01). Posterior staphyloma height was significantly correlated with refractive error and axial length (P < 0.01). Stepwise analysis indicated that choroidal thickness correlated significantly with age and posterior staphyloma height (P < 0.01).

Posterior staphyloma formation was a key factor in choroidal thinning in highly myopic eyes. Choroidal thickness had a greater effect than retinal thickness in highly myopic eyes.