IN-VIVO MORPHOMETRY OF THE LAMINA-CRIBROSA AND ITS RELATION TO VISUAL-FIELD LOSS IN GLAUCOMA

Purpose. The lamina cribrosa has been proposed as a site of origin of the optic nerve damage in glaucoma. The purpose of this study was to i nvestigate, in vivo, the clinical features of the lamina cribrosa pore s of glaucomatous patients and to relate their morphometric characteri stics to the extent of their visual field loss. Methods. Images of the internal lamina cribrosa surface of 60 glaucomatous patients and 15 n ormal subjects were acquired, in vivo, using a scanning laser ophthalm oscope (SLO). A purposely developed technique of image processing was employed to objectively evaluate pore morphometry, with particular reg ard to their geometrical characteristics (circularity and elongation). Visual function was assessed by automated perimetry (Humphrey Field A nalyser). Results. Normal subjects showed approximately round lamina p ores. In glaucomatous patients, pores become more elongated and less c ircular with increasing field loss (p = 0.009 and p < 0.001, respectiv ely). Conclusions. Scanning laser ophthalmoscopy and a new technique o f image processing were employed, for the first time, to the investiga tion in vivo of the lamina cribrosa of glaucomatous patients, in relat ion to the extent of visual field loss. The results indicated differen ces in the lamina cribrosa pore morphometry associated with increasing severity of the disease. These changes may represent the result of co mpressing and shearing forces applied to the laminar plates.