Search

We examined the difference in response to different degrees of injury in the mouse lens. The anterior side of the lens was pricked through the cornea by a microsyringe with a 31-gauge needle or an ordinary needle. The location of the needle tip was mostly marked with Evans' blue (EB) stain. At least three types of responses were recognizable. The first was a recovery type in which the wound was healed by an epithelial reaction. EB was localized at the superficial zone of the anterior cortex. The second was a type in which the change within the lens was stationary after forming a spherical body with a slightly smaller diameter than that of the entire lens. EB was observed in the intermediate zone of the anterior cortex. The third was a rapid progressive type of cataract which caused lens opacity within 3 days. The trace of the needle tip was observed around the perinuclear zone. These results suggest that the cortex of the mouse lens consists of three zones which may be functionally different around the lens nucleus: superficial, intermediate and perinuclear zones.

Purpose: To develop a universal standard for comparison of the results from different studies using Scheimpflug photography. Material and Method: A suspension including polystyrene spheres was selected as the universal standard. The polystyrene suspension was diluted into 10 concentrations by adding spectroscopic quality water. An artificial eye chamber was designed to hold the diluted suspension for photography. Each concentration was photographed by both a Topcon SL-45 slit-lamp camera and a Nidek EAS-1000 system. The intensity of back-scattered light was analyzed statistically. Results: The relationship between the concentration of the polystyrene suspension and the internal gray scale step within the Topcon SL-45 camera can be described by a second-order polynomial. The relationship between the concentration of the polystyrene suspension and the measurement of the Nidek EAS-1000 system can also be expressed by a second-order polynomial. The relationship between the Topcon SL-45 camera and the Nidek EAS-1000 system is linear. Conclusions: The results of lens nuclear opacity measured with different Scheimpflug cameras can be compared using the method established in the study. The linear relationship between the Topcon SL-45 and Nidek EAS-1000 systems can be used to convert measurements from one system to the other.

Age-related lens opacity is the major cause of loss of vision affecting more than half of the world's blind. The development of cataract is associated with changes in the structure of the lens. The lens consists largely of closely packed fibre cells forming a transparent syncytium. The main intrinsic polypeptide (MIP) of the lens fibre cells forms 40% of the fibre membrane, and forms a system of membrane channels. The precise structure and function of these channels remains obscure, although their role as large water-filled channels has been suggested in maintenance of structural integrity as well as their role in transport of nutrients. MIP is a member of a large family of channels of common ancestry. Some of the most recent studies of structure and function of this family have been carried out on CHIP (a water channel found in red blood cells) which is a member of this family closely related to MIP. Both CHIP and MIP m-RNA's have been expressed in oocyte membranes, and water permeabilities per channel have been measured. Surprisingly, CHIP and MIP channels have high and low water permeabilities, respectively. This is discussed in terms of recent high resolution structure determinations, the lens fibre MIP function, and future studies.

The knowledge of the multifactorial genesis of the so-called senile cataract has initiated an intensified search for cataract-related risk factors. The mechanisms of syn- and cocataractogenesis could already be shown in the Department of Experimental Ophthalmology, Bonn, in the seventies. Subsequently, cataract epidemiology became a field of interest in 1980 when all available epidemiological data related to cataract research were first collected and reviewed. It has become obvious that the various types of cataract morphology do not represent one unique disease ‘senile cataract’ but reflect different biochemical characteristics. A preliminary study assigned data of case history as well as blood and lens biochemistry to four types of lens opacity. Scheimpflug photography and multilinear microdensitometry were the basis for classifying cataract lenses. After increasing the number of involved patients, the data were analyzed by means of multivariate statistics. The originally used cataract classification system was enlarged to eight types of frequently seen cataract morphologies. A control group was built up to enable case-control studies as well as to obtain characteristics of normal lens density related to age.

The lens opacity meter, a recently developed clinical device for the examination of cataractous lenses, was used to evaluate nuclear opacification. In 215 noncataractous lenses of subjects aged 6–86 years, the opacity value (OV) ranged from 5.2 to 24.8 and increased with ageing. The OV measured in cortical cataracts with intrapupillary opacification was relatively higher than that without opacities. The scattered light intensity of the nuclear zone, measured from a Scheimpflug image, correlated well with the OV. In some cases with noncataractous eyes, the correlation between small-sized protein particles and the OV was examined. The lens opacity meter is useful to objectively evaluate changes in nuclear opacity.

Since oxidative stress is a well substantiated hypothesis of cataract pathogenesis, screening was performed in acellular systems in order to select scavengers of reactive oxygen species; the selected compounds are at present being tested in lens culture and in animal models.

Freshly isolated rabbit lenses were cultured in isosmolar TC-199 medium or hyperosmolar medium containing 180 mM sorbitol or mannitol. These experiments were performed to investigate the probable effects of hyperosmolar media on lens clarity and the ability of lens fiber cells to synthesize membrane intrinsic protein, MP-26. The data from these experiments show that incubation in hyperosmolar medium causes depressed MP-26 synthesis, whereas the presence of sugar alcohols in the culture medium induced anterior and posterior subcapsular opacities. The cation levels of lenses incubated in iso- and hyperosmolar medium were also measured. Data from these experiments revealed that although the experimental lenses display prominent opacities, their cation levels are generally similar to those of control lenses. It is proposed that the observed lens opacities are due to the presence of sugar alcohols in the culture medium and not to hyperosmolar shock.

The effect of the antibiotics gentamycin and chloramphenicol on lens opacity was studied in an organ culture system. Opacity was monitored by split laser beam. Both antibiotics enhanced the onset of opacity in the cultured lenses under a variety of conditions. For instance, treatment with 5.0 mg/ml gentamycin for 60 min caused initial opacity after 4.8 +/- 1.3 days as opposed to untreated lenses at which initial opacity appeared after 18.1 +/- 2.99 days. Exposure to 20 mg/ml chloramphenicol for 60 min caused initial opacity after 4.6 +/- 1.51 days. Continuous exposure to penicillin and streptomycin (0.1 mg/ml each) did not enhance the onset of opacity.