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 m yopic eyes with absolute secondary angle closure glaucoma. Methods-Opt ic 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 wer e histomorphometrically evaluated. All eyes had been enucleated due to painful absolute secondary angle closure glaucoma. Results-In the hig hly myopic eyes compared with the non-highly myopic eyes, mean optic d isc 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 pe ripapillary scleral ring was significantly broader (0.58 (0.65) mm ver sus 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 w as significantly larger in the highly myopic eyes. Conclusions-The res ults 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 addit ion to alpha and beta zone to the parapapillary atrophy.