How should cataracts be measured?

Cataract and cognitive impairment: a review of the literature

Acquired cataract and cognitive impairment are both common age-related problems, and ophthalmologists are increasingly likely to encounter patients who have both. Patients with dementia types who display early visuoperceptual impairment may present first to ophthalmology services. When these patients have coexisting cataract, it may be difficult to distinguish visual complaints due to cataract from those due to dementia. The interaction between visual impairment due to cataract and neurodegenerative disorders affecting the central visual pathways, is not fully understood. Visual impairment due to cataract may stress impaired attentional mechanisms and cataract extraction may improve cognitive performance in some patients with early cognitive impairment; however, the benefits of cataract surgery in established dementia are less clear. In this study, the literature on this subject was reviewed and the implications for practice were considered.

The Pyhäjärvi Cataract Study. I. Study design, baseline characteristics and the demand for cataract surgery

PURPOSE

The Pyhäjärvi Cataract Study aims to study demand for cataract surgery in the population of a rural town in Finland.

METHODS

A random, population-based sample of 881 persons aged > or = 60 years were interviewed by telephone to obtain a Visual Function-14 (VF-14) score. A total of 294 persons were invited for an ophthalmic examination based on three categories of VF-14 score. Of these, 230 (78%) responded, 10 of whom were excluded as a result of prior bilateral surgery. The New Zealand Priority Criteria (NZPC) and the 15-Dimension Quality of Life (15-D) instruments were administered. In addition, another group of 96 patients waiting for cataract surgery were examined and scored using the VF-14, NZPC and 15-D instruments. A modified Lens Opacities Classification System (LOCS) III classification was used for grading the cataract.

RESULTS

Only one (0.5%) of the 220 examined subjects was referred for cataract surgery. Many patients with relatively good visual acuity (VA), including six people with a 100-point VF-14 score suggesting no visual symptoms, were waiting for surgery. Demographic factors were not associated with access to cataract surgery. The patients examined from the waiting list for cataract surgery had more cataractous changes in the lens(es), poorer VA, were older, and scored higher on the NZPC instrument than the population sample examined.

CONCLUSIONS

Practically no hidden demand for cataract surgery was found in the study population as defined by the national criteria for cataract surgery in Finland. This reflects the fact that the current Finnish health care system appears to recognize and treat cataract patients very well, even in rural areas. Although VA tests may not be sufficient for evaluating need for cataract surgery, the role of questionnaires is not clear either.

Risk factors for cataract subtypes waterclefts and retrodots: two case–control studies

Waterclefts and retrodots are independently associated with visual impairment, yet a review identified no data on risk factors.

PURPOSE

To investigate risk factors for these two human lens cataract subtypes.

METHOD

Two nested case-control studies: The host study comprised 1078 subjects (55 years) attending the Somerset and Avon Eye Study (SAES). In total, 197 watercleft cases (Oxford grade 0.2 in either eye) and 199 retrodot cases (Oxford grade 1.0 in either eye) were individually age/gender matched to controls. Detailed ophthalmic and potential risk factor data were collected, including body mass index (BMI), smoking, alcohol, diabetes, hypertension, analgesics, vitamin supplementation, nutrition, sunlight exposure, dehydration, hormonal (women), blood lipids, glucose, urea, creatinine, uric acid, and vitamin levels.

RESULTS

For waterclefts, univariable analysis identified BMI, alcohol intake, vitamin status, sunlight, urea, creatinine, and uric acid as possible risk factors. Multivariable analysis identified two independent associations. Total number of 'any' analgesics in the previous year: adjusted P<0.01 (U-shaped risk profile, unadjusted high vs medium use (=reference) OR 2.39, 95% CI 1.35-4.26 with medium use vs none (=reference) OR 0.43, 95% CI 0.26-0.72); total sunlight: adjusted P=0.03 (unadjusted highest exposure vs lowest (=reference) OR 3.25, 95% CI 1.11-9.50). For retrodots, univariable analysis identified alcohol, HRT, and lipids. Multivariable analysis identified two independent associations. Mean number of alcohol units consumed per month, adjusted P=0.02 and HDL cholesterol levels, adjusted P=0.02 (unadjusted ORs NS both).

CONCLUSION

This is the first available published information on risk factors for the human cataractous lens features waterclefts and retrodots.