Histomorphometry of the optic disc in highly myopic eyes with absolute secondary angle closure glaucoma.

AIM To evaluate histomorphometrically the optic nerve head in highly myopic eyes with absolute secondary angle closure glaucoma. METHODS Optic disc sections of 16 highly myopic eyes with an axial length of more than 26 mm and of 19 eyes with an axial length of less than 26 mm were histomorphometrically evaluated. All eyes had been enucleated due to painful absolute secondary angle closure glaucoma. RESULTS In the highly myopic eyes compared with the non-highly myopic eyes, mean optic disc diameter was significantly larger (mean 2.33 (SD 0.55) mm versus 1.77 (0.50) mm; p = 0.01), and the optic cup was significantly shallower (optic cup depth 0.34 (0.29) mm versus 0.63 (0.23) mm; p = 0.03). The peripapillary scleral ring was significantly broader (0.58 (0.65) mm versus 0.08 (0.06) mm; p = 0.001), and the beta zone (0.83 (0.74) mm versus 0.28 (0.25) mm; p = 0.006) of the parapapillary chorioretinal atrophy was significantly larger in the highly myopic eyes. CONCLUSIONS The results of the present study agree with biomorphometric data of the optic nerve head in highly myopic eyes with glaucoma. In the highly myopic group, a markedly enlarged peripapillary scleral ring characterised by absence of Bruch's membrane and choriocapillaris contributes in addition to alpha and beta zone to the parapapillary atrophy.