[A study on the structure of human lamina cribrosa sclerae]

The lamina cribrosa of 15 normal adult human eyes were observed by scanning electron microscopy and their images were analyzed by a computerized system to study the distribution of pores and the proportion of connective tissue in different regions of the lamina cribrosa. The results revealed that there are significantly more large pores (> or = 3,000 microns2) in the superior and inferior than those in the nasal and temporal quadrants, especially in the peripheral regions, however, in terms of area the percentages of connective tissue in the nasal and temporal quadrants are the highest. In addition, the histological study of the lamina cribrosa disclosed that the collagenous fibers, various in calibre, are arranged in bundles and tangentially around each pore. Since the nerve fiber damage in glaucoma initially occurs at the superior and inferior parts of the optic nerve, the above anatomical characteristics possibly can explain the cause of the visual field defects in early glaucoma.