The assessment of lens opacities in clinical practice: results of a national survey

Descriptive and risk factor analysis of infantile cataracts: National Birth Defects Prevention Study, 2000-2011

Using National Birth Defects Prevention Study (NBDPS) data, we sought to estimate birth prevalence, describe clinical characteristics, and examine risk factors for infantile cataracts. We calculated birth prevalence using the numbers of NBDPS-eligible cataract cases and live births in the study area. We described case infants by the presence of associated ipsilateral eye defects (IEDs) and non-eye-related major birth defects. Using maternal exposure information collected via telephone interview, we conducted logistic regression analyses among the interviewed cases and controls. Birth prevalence of infantile cataracts was 1.07/10,000 live births. Unilateral cataracts were more often associated with IEDs, while infants with bilateral cataracts were more often preterm, full-term with low birth weight, or had non-eye-related major birth defects. Unilateral cataracts were positively associated with maternal nulliparity (adjusted odds ratio [aOR] = 1.61, 95% confidence interval [CI] = 1.18, 2.20; reference: multiparity), whereas bilateral cataracts were positively associated with maternal education <12 years (aOR = 2.08, 95% CI = 1.13, 3.82; reference: education >12 years), and foreign-born nativity (aOR = 1.92, 95% CI = 1.04, 3.52; reference: U.S.-born nativity). The current analysis can inform future epidemiological studies aimed at identifying mechanisms underlying the associations between infantile cataracts and complex maternal exposures, such as lower levels of education and foreign-born nativity.

Awareness of treatment: A source of bias in subjective grading of ocular complications

PURPOSE

Bias has been described as one important obstacle in scientific research. The aim of this study was to explore "awareness of treatment" as a possible source of bias in subjective grading of ocular complications.

METHODS

Thirty subjects with similar, basic experience with grading scales participated in the study. The Efron grading scales were used to grade 24 images of three different ocular conditions (eight images each of bulbar hyperaemia, limbal vascularization and corneal staining). Three consecutive, two weeks apart, grading sessions were scheduled, in which the same images were graded, although in the third session images were deceptively labelled as either "treated" or "untreated". Grading results from the first and second sessions were compared to determine grading reliability and discrepancies with the third session informed of grading bias originating from "awareness of treatment".

RESULTS

Moderate to good test-retest reliability was found for all conditions, with median intraclass correlation values of 0.80 (0.62-0.84) for bulbar hyperaemia, 0.68 (0.65-0.77) for limbal vascularization and 0.68 (0.66-0.74) for corneal staining. Grading values from the first and third sessions evidenced negative and positive systematic errors (bias) for "treated" and "untreated" conditions, respectively. Statistically significant differences were found between the average grading discrepancies of session 1 and session 2 and those of session 1 and session 3 (all p<0.001).

CONCLUSIONS

"Awareness of treatment" may be considered a source of bias of subjective grading of ocular complications, although the actual effect of bias is unlikely to be of clinical significance.

Retrodots in the lens in the Beaver Dam Eye Study cohort

OBJECTIVE

To determine the prevalence of retrodots in the lens and the association of these lesions to age-related cataract, and to assess their association with visual impairment and contrast sensitivity.

DESIGN

Longitudinal epidemiologic study.

PARTICIPANTS

The Beaver Dam Eye Study cohort.

METHODS

Eye examinations including grading of standard photographs of the lens and measures of visual function.

MAIN OUTCOME MEASURES

Statistical associations of retrodots with nuclear, cortical, and posterior subcapsular cataracts and with incident visual impairment and impairment of contrast sensitivity.

RESULTS

The prevalence of retrodots at the baseline examination increased with age from 1.68% in those 43 to 54 years of age to 31.20% in those ≥ 75 years of age. After controlling for age, there was no significant difference in the prevalence of retrodots between men and women. The odds ratio (OR) for visual impairment associated with retrodots was 2.22 (95% confidence interval [CI], 1.80-2.75) after controlling for age-related cataracts and other associated characteristics. The association with impaired contrast sensitivity was not significant. Retrodots were not significantly associated with incidence of any type of age-related cataract. The 15-year cumulative incidence of retrodots in right eyes increased with age from 9.3% in those 43 to 54 years of age to 21.1% in those ≥ 75 years of age. In addition to age, incidence of retrodots was independently associated with smoking (OR, 1.27; 95% CI, 1.04-1.56 for ever vs never smoking).

CONCLUSIONS

Retrodots are frequently occurring age-related lens opacities that are associated with decreased vision independent of the presence of age-related cataract. Their incidence is associated with smoking. Further research to determine the underlying process leading to retrodots is necessary before efforts to develop preventions are undertaken.

The morphology and natural history of childhood cataracts

The morphology of congenital cataract reflects a combination of the timing and nature of the cause, the anatomy of the lens including its capsule, its development, and changes that take place with time. Morphology may variably affect prognosis, give a clue to the etiology and the age of onset and, in an isolated case, sometimes suggest heritability. The spectrum of morphological variations is enormous and can be complex. A comprehensive approach is to classify the variations according to the area of the lens involved, and sub-dividing them by a detailed description of the shape and appearance. Each specific morphological type is then analyzed determining the etiology, visual prognosis, and management. The use of gene markers has allowed many of these variations to be identified and categorized. Cataracts in childhood can involve the whole lens, in which case they are called total, Morgagnian, or disk-like. They can affect only the center of the lens: lamellar, nuclear, oil droplet, cortical, or coronary. They can be anterior: anterior polar, anterior subcapsular, or anterior lenticonus. The posterior aspect of the lens can also be affected in different fashions: Mittendorf's dot, posterior lenticonus, posterior cortical cataracts, or posterior subcapsular. There are five more forms that must be described separately: punctuate lens opacities, sutural cataracts, coralliform or crystalline, wedge-shaped, and persistent hyperplastic primary vitreous.

The population requirement for cataract extraction: a cross-sectional study

PURPOSE

To examine the distribution in the population of indications for cataract extraction in order to relate demand for this procedure to the capacity for satisfying it.

METHODS

An age-stratified random population sample of 2783 individuals aged 55 years and over was taken from inner-city, urban and rural areas of Avon and Somerset. The requirement for cataract extraction was estimated on the basis of measures of vision-related quality of life, refracted visual acuity, and application of the Oxford Clinical Cataract Classification and Grading System. Data were also collected concerning suitability for surgery, including relative contraindications to surgery and whether participants considered their eyesight bad enough to merit surgery. Three sets of composite indications were defined.

RESULTS

Estimated prevalent requirements for cataract extraction for the three sets of composite criteria were: 29 per 1000 aged over 55 years (95% CI 20-41) for the most inclusive criterion; 17 per thousand (95% CI 10-27) for the intermediate criterion; and 7 per thousand (95% CI 3-14) for the most stringent criterion. These rates are equivalent to a national prevalent requirement for England of 384,000 for the most inclusive criterion. If the approximately 15% of individuals whose desire or fitness for surgery was questionable are removed from this estimate, the prevalent requirement, including the backlog from previous unsatisfied demand, becomes 325,000 individuals.

CONCLUSIONS

The findings suggest only a modest imbalance between supply and demand for cataract surgery. In particular there was a very small prevalence of untreated severe cataract, less than the annual health service surgical capacity, suggesting that the current National Health Service surgical capacity is adequate for cases of severe cataract.