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Kurt O. Gilliland, Sangeetha Metlapally, Ashik Mohamed, D Balasubramanian, Sönke Johnsen, W C. Fowler, M J. Costello; Nuclear Cataracts with Different Morphologies Display Distinctive Fiber Cell Damage. Invest. Ophthalmol. Vis. Sci. 2011;52(14):802.
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© ARVO (1962-2015); The Authors (2016-present)
To identify the characteristic ultrastructural damage in a variety of human nuclear cataracts that have very different appearances after extracapsular extraction. Common age-related nuclear cataracts are compared with less common hypermature, black and white cataracts.
Fresh human lens nuclei, from the US and India, were Vibratome sectioned, immersion fixed and en bloc stained with uranyl acetate and osmium tetroxide prior to dehydration and embedding in epoxy. In 70 nm thin sections of different nuclear regions, fiber cells were imaged at 80 kV with a CCD camera on a Tecnai 12 transmission electron microscope.
Cell damage in age-related nuclear cataracts was, as described previously, mainly (a) minor damage to membranes with narrow extracellular space (ECS) and some deposits within the ECS, (b) slight increase in cytoplasmic texturing, and (c) consistent presence of 1-4 µm multilamellar bodies. Hypermature cataracts exhibit enlarged ECS and more damage around membranes as well as in situ fiber cell disintegration. Black cataracts have essentially the same ultrastrucuture as age-related cataracts. Gross examination of white cataracts reveals that nuclei have little coloration and are opaque due to extensive white scattering. These nuclei have highly textured cytoplasm, numerous multilamellar bodies and globular cell disruptions.
Each nuclear cataract type has distinguishing ultrastructural features. The increased cell breakdown and enlarged ECS in hypermature cataracts are consistent with cortical cell disintegration and extensive white scattering of the nucleus. The similarity of black cataract to more common age-related cataracts suggests that the gradual build up of lens pigments to the point of opacification can occur with only minor alterations to cell structure. Conversely, limited pigment build up in white cataracts is coupled with extensive cell disruption.
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