Epidemiology of Cataract

Chlorpromazine and several other phenothiazine neuroleptic drugs appear to induce cataract formation. However, the newer generation of antipsychotic agents has shown no evidence of an etiologic relationship with cataract occurrence. Research did reveal cataract occurrence in dogs who received quetiapine, which prompted concern despite there being no known causal link between quetiapine and lens opacities in humans. Nevertheless, quetiapine's manufacturer issued formal recommendations for ophthalmological follow-up examinations with the use of this drug. Infrequent occurrences of cataract development have been documented in people taking olanzapine but, again, without established causative association; a similar situation is seen with ziprasidone. Periodic ocular examinations of the lens are suggested for patients prescribed long-term treatment with phenothiazines or quetiapine.

To compare the distribution of cataract types between psychiatric patients diagnosed with schizophrenia and the general population not exposed to psychotropic medication, and to compare cataract prevalence between users and nonusers of various psychotropic medications in the general community.

Case-control.

A total of 151 (93%) eligible patients from a community mental health service and 3271 (83%) eligible residents from the Melbourne Visual Impairment Project (VIP) were examined.

All patients 40 years of age and older from a community mental health service and residents of nine randomly selected areas of Melbourne were eligible. Best-corrected distance visual acuity was determined using a 4-m logarithm of the minimum angle of resolution (LogMAR) chart. The presence of cataract was determined by photographs or slit-lamp examination using direct and indirect retroillumination. Anterior, cortical, nuclear, and posterior subcapsular cataracts were measured. Participants from the Melbourne VIP were classified as to whether they had taken benzodiazepams, phenothiazines, thioxanthenes, butyrophenols, tricyclic antidepressants, or monoamine oxidase inhibitors for at least 12 months during their lifetime.

The distribution of cataract type varied between persons with and without schizophrenia. Anterior subcapsular (ASC) cataract was significantly more prevalent (26%) in participants with schizophrenia from the community mental health service than Melbourne VIP participants (0.2%) not exposed to psychotropic medication (chi-square, 1 degree of freedom = 605.5, P = 0.001). This remained significant after controlling for age (odds ratios = 250, 95% confidence interval = 83.3, 1000). The distribution of the age-related cataract was similar across all groups of psychotropic medication users with the exception of the phenothiazine users. They had less of all types of the age-related cataracts, despite being slightly older than the control group (mean age, 60.0 vs. 58.4, t test = 0.85, P = 0.40). However, only cortical cataract in the phenothiazine group was statistically lower (chi-square, 1 degree of freedom = 3.96, P = 0.047).

This study has identified the need to investigate whether other newer agents, especially high-potency medications, cause ASC opacities if a certain threshold of exposure to psychotropic medications must be attained to develop cataract, or if schizophrenia itself is associated with cataract formation.

Corticosteroids are known to cause cataracts, but the effects of other medications on the lens are unclear. The aim of this study was to investigate the relationships between cataracts and a range of medications, including allopurinol, aspirin, chloroquine, diuretics, phenothiazines, and simvastatin.

Population-based cross-sectional study.

3654 individuals 49 to 97 years of age (response rate, 82%) from an urban community near Sydney, Australia, were included.

Lens photography.

Lens photographs were graded for the presence and severity of cortical, nuclear, and posterior subcapsular cataract.

After adjusting for numerous potential confounders in ordinal regression models, use of phenothiazines was associated with nuclear cataract (adjusted odds ratio [OR], 2.18; 95% confidence interval [Cl], 1.01–4.74); long-term aspirin users (≥10 years) had higher prevalence of posterior subcapsular cataract than did nonusers and short-term users (test for trend, P = 0.02); and the antimalarial drug mepacrine was associated with posterior subcapsular cataract (adjusted OR, 3.56; 95% CI, 1.56–8.13). There was a suggestion that use of chloroquine-like drugs for more than 1 year (test for trend, P = 0.12) might also be associated with posterior subcapsular cataract. Antihypertensive medications, cholesterol-lowering drugs, and allopurinol were not associated with any type of cataract. Potassium-sparing diuretics were the only diuretic to show any evidence of an association with cataract (test for trend for posterior subcapsular cataract, P = 0.14). Amiodarone was associated with cortical cataract (age- and gender-adjusted OR, 3.84; 95% CI, 1.01–14.81), but there were too few users to do analyses adjusted for multiple confounders.

Most drugs commonly used in the community do not appear to be associated with cataract. The findings of this study do not support the hypothesis that aspirin protects against cataract.

22% of a group of adult Neapolitans were found to have persistent high lactase activity, and 16% were lactose absorbers as indicated by measurement of breath hydrogen concentration and rise in blood glucose after oral lactose administration. Among adults in the same area with idiopathic senile or presenile cataract 49% were identified as lactose absorbers with the breath hydrogen test and 55% by the rise in blood glucose. These results suggest that adults able to absorb galactose from a lactose-containing diet are especially susceptible to senile or presenile cataract.

A photochemical theory of the etiology of senile cataract is developed on the assumption that observed prevalences are representable by cumulants of tolerances, the latter being distributed normally and depending in a quantitatively defined way on the amount of short-wavelength radiation absorbed during life. The theoretical risk-curves are consistent with the observed ones. The variation of the predicted and observed values has a slope not differing significantly from unity, but the intercept differs from zero. It is concluded tentatively that the photochemical hypothesis accounts for the observations better and better as age advances, and more so where the radiation is more intense.