Sources of variance in the objective documentation of human cataractous change with Topcon SL-45 and Neitz-CTR retroillumination photography and computerized image analysis.

In the application of Topcon SL-45 Scheimpflug slit and Neitz CTR retroillumination photography to in vivo documentation of cataractous change, several sources of variance affect the results of each technique. We have measured the between-person, between-photographer, between-focal plane (Neitz), between-photo session, replicate photograph (Topcon), between-image analyst and replicate image analysis variances encountered in in vivo documentation of human cataracts with the Topcon SL-45 and Neitz-CTR cameras and our system of computerized image analysis.

Quantitative detection of the molecular changes associated with early cataractogenesis in the living human lens using quasielastic light scattering.

We have used quasielastic light scattering to detect and quantitatively characterize the molecular changes associated with the early stages of cataractogenesis in the living human lens. The autocorrelation function of the fluctuations in the light scattered by the lens shows the presence of two major species responsible for the scattering. The first, fast diffusing species (f), has a diffusivity of approximately 3 x 10(-7) cm2/sec and corresponds to the alpha crystallin proteins. The second, slow diffusing species (s), has a diffusivity of approximately 10(-9) cm2/sec and corresponds to the diffusivity of a large aggregate. The intensity of light If and Is scattered into the collection optics by each of these species was also measured. We studied a group of 49 individuals ranging in age from 21 years to 82 years. In this group 40 presented with preoperative cataract development. In this patient population we found that regardless of age, or position in the lens that a plot of Itot = If+Is versus Is could be well fitted by a straight line with a slope less than unity and a positive intercept Ifo. It has been possible to explain this finding using a two state model for the molecular changes associated with early cataractogenesis. In this model the proteins in the slow diffusing species are aggregates each containing a definite number of rapidly diffusing proteins. The early development of cataract is represented by the redistribution of protein between the unaggregated form (f) and the aggregated form (s). The prediction for the relationship between Itot and Is based on this two state model is in very good agreement with our experimental data. Indeed the measured position of the point (Itot, Is) along this line provides a sensitive, and quantitative measure of the degree of cataract development at any selected location in the lens.

Progress toward developing a cataract classification system.

A cataract classification system is being developed based on a set of standard photographs. The system uses an ordinal scale ranging from 0 (no opacities) to 2 (definite opacities) to classify cataractous changes in the nuclear, cortical, and posterior subcapsular lens zones. The reproducibility of slitlamp-derived and photo-derived classifications using the system was evaluated. The reproducibility between 2 observers for slitlamp-derived classifications was very high (n = 60). The reproducibility within and among 4 photography readers was also good for photo-derived classifications (n = 100). Discrepancies were found between ratings derived from slitlamp examinations and from photographs; such discrepancies were most frequent for gradings of cortical opacities.

Pseudomonas cepacia endophthalmitis.

A 72-year-old white man who had undergone surgical trabeculectomy and extracapsular cataract extraction with a posterior-chamber lens implantation in the left eye suffered from chronic iridocyclitis for eight months. He subsequently presented with acute hypopyon and vitritis. Anterior-chamber and vitreous cultures were positive for Pseudomonas cepacia. The infection was successfully treated with subconjunctival piperacillin, intravitreal cefotaxime, and intravenous piperacillin and gentamicin. To our knowledge, this is the first documented case of Pseudomonas cepacia endophthalmitis.