Study of choroidal thickness in highly myopic eyes with and without dome shaped macula.

Abstract

Purpose: The dome shaped macula (DSM) is a clinical entity recently described in association with a myopic staphyloma, which may cause a decreased vision. The purpose of this study was to evaluate the choroidal thickness of eyes with DSM and to compare these results with those of myopic eyes without DSM.

Methods: 26 patients with a dome shaped macula were included in this retrospective study. All patient underwent a complete ophthalmological assessment including a SD-OCT (Spectralis, Heidelberg, Germany) examination using the "7 lines EDI (Enhanced Depth Imaging)" protocol (Eyevue, Spectralis, Heidelberg, Germany). An axial length (AL)-matched group of 26 myopic eyes without DSM was also studied. Mean choroidal thickness in the central, nasal and temporal areas of the ETDRS grid were obtained by mapping the choroid with the 7 EDI lines in the corresponding areas. The results were compared in both groups.

Results: The mean AL was 27.2 mm in the DSM group and 27.1 mm in the group without DSM. No difference was found between the two groups (p> 0.05). The mean choroidal thickness in the DSM group was 123μ, 159μ and 138μ in the nasal, central and temporal areas respectively. In the group without DSM, the corresponding thicknesses were 159μ, 177.7 and 187.2 μ. The central and nasal choroidal thickness were not significantly different between the 2 groups (p=0.25 and 0.33 respectively). The decrease in temporal thickness in the DSM group was closer to significance (p=0.07). The ratio between central choroidal thickness and "peripheral" nasal and temporal thicknesses was very significantly increased in the DSM group (1.13 vs. 0.99, p=0.0014). Central choroid thickness in the MB group was greater in the vertical DSM type than in the horizontal and dome types (184μ vs 138μ p=0.004). There was no difference in AL between the vertical DSM and other DSM types (p>0.05).

Conclusions: These results suggest that choroidal thickness decreases in the periphery of the bulge and not in the central macular area in eyes with DSM compared with eyes without DSM. This may indicate that dome shaped macula is not due to the development of an inward protrusion of the globe but to a preservation of the macular anatomy in a growing staphyloma. Serous Retinal Detachment have been reported more frequent in vertical DSM types, this could be due to an increased central macular thickness in those forms, like in central serous chorioretinopathy.

Keywords: 452 choroid • 585 macula/fovea • 605 myopia