180 CHAPTER SIX ducing a grey to white pupillary color. Supplementary examination on dilated eyes revealed the condi- tion of the lens, optic nerve, and retina as well as ocular tensions. Lenticular opacities were noted as central, peripheral, or both. The status of the optic disc and/or retina was also noted when it was not obscured by opacities. When opacities obscured direct ex- amination of the posterior segment, indirect measures (perception of light and pupillary reflex) were used to evaluate its status. With the information obtained by direct examination and the results of visual acuity screening, the ophthalmologist made a clinical judgment regarding the lens, first noting if cataract existed or not. If cataract was present, it was classified as incipient, immature, mature, or after-cataract membrane. If the lens was absent, it was noted as dislocated, couched, or aphakic. Clinical evaluation of cataract stage was tempered by the presence of corneal opacities, iris deformities, or inability to visualize the lens for any reason. The guidelines for grading cataract stage in the absence of corneal scars or other obstructions of the visual axis were as follows: (1) Incipient cataracts19 were those with an early color change indicative of slight opacity, slight reduction of red reflex, slight reduction of retinal detail, and possibly but not necessarily some change in visual acuity. (2) Immature cataracts were those with marked reduction of the red reflex, hazy fundus detail, and a brown or grey pupil. (3) Mature cataracts were indicated by grey to white pupillary color (sometimes dark brown), absence of red reflex, and fundus detail not visible. • (4) After-cataract was used to describe membranes of cataract capsule and cortical material incompletely removed during surgery or formed after couching. Ophthalmologists recorded their impression of cataract cause on the basis of early age of onset (congenital), intercurrent or concur- rent disease (inflammatory or infectious), accidents (traumatic), degenerative (senile), or cause unknown. Senile cataract was often a diagnosis made by exclusion of other causes. 6.2.3 Quality of Cataract Data The quality of findings regarding cataract depends upon many fac- tors, including research design, sampling method, coverage and response rates, sensitivity and specificity of diagnostic criteria, interobserver agreement, and the reliability of the measures used to assess cataract. Most of these issues are discussed elsewhere in
