Purpose
Recently, myopia was found to increase the susceptibility to intraocular pressure and myopic eyes were at higher risk of developing open-angle glaucoma (OAG). The pathogenesis has been postulated to be morphologic changes around the optic nerve head (ONH) along with axial length elongation. We recently found that the peripapillary morphology is related closely to the type of posterior staphyloma (PS). We compared the PS shape with and without OAG using swept-source optical coherence tomography (SS-OCT).
Methods
We retrospectively studied highly myopic eyes (refractive error <-6 diopters [D] or axial length >26 mm) with (group G, 74 eyes) and without (group N, 83 eyes) glaucomatous optic neuropathy. Only eyes with OAG were included. The depth of the posterior staphyloma was measured in a 12-mm horizontal SS-OCT scan. The staphyloma depth was defined as the average distance between the position of the retinal pigment epithelium (RPE) under the fovea and that 3 mm temporal or nasal to the fovea. The shape of the PS was evaluated by the relative location of the fovea and the ONH. The optic disc type was one in which the foveal surface was more anterior than the anterior surface of the pre-laminar tissue and vice versa for the non-optic disc type (Fig.).
Results
The mean refractive error was -8.42 ± 0.72 D in group G and -11.04 ± 0.58 D in group N (P=0.04). The mean axial length was 29.94 ± 0.19 mm in group G and 28.70 ± 0.18 mm in group N (P<0.01). The staphyloma was significantly deeper in group N (335.0 ± 22.6 μm) compared with group G (192.1 ± 24.4 μm) (P=0.04). The incidence of the optic disc type in group G was significantly higher than that in group N (P=0.04). In group G, there was no significant correlation between the mean deviation value in Humphrey visual field test and the staphyloma depth (P=0.58) or staphyloma shape (P=0.46).
Conclusions
Eyes with OAG have specific characteristics in myopic eyes. The morphologic changes seen in these eyes seem to be related to the increased risk.
Keywords: 550 imaging/image analysis: clinical •
605 myopia