Epidemiology of strabismus.

Abstract

In a short paper such as this, it would be a mistake to attempt a comprehensive review of our knowledge of the occurrence of strabismus and those characteristics of populations which may lead to variations in its incidence. To do so would subject us all to mental dyspepsia from a surfeit of information which none of us would have time to consider critically. Instead, I propose to take certain aspects of the epidemiology of strabismus, and to illustrate these by some observations made in Cardiff, with occasional data from other sources.The sort of questions we can hope to answer by epidemiological studies are those concerned with the prevalence of squint:How common is it?Does the prevalence vary from one community to another, and if so, can we identify any characteristics of these communities which may explain the difference?How do new cases arise, and at what ages?The first of these questions can be answered reasonably accurately, but the others present difficulties. The common snag in population research is that a study of previously published work reveals that sampling methods and criteria used in definition are either not stated or differ so much from one another that it would be most unwise to draw any conclusions from comparisons of prevalence. As a result, it becomes necessary to use mainly internal comparisons, and in particular the techniques of comparing a group of strabismic patients with a group of non-strabismic patients drawn at random from the original population, and examined by the same techniques. A number of the comparisons I shall present comes into this category. Material and techniquesA brief description of the nature of our population and our examination procedures and definitions is clearly the first step in describing some of our results.Our sample consisted of all the children born in the City of Cardiff between January I and December 3I of one year. The details of the 4,832 children born within these limits were obtained from the birth records maintained by the Medical Officer of Health, and the children were examined wherever possible at school during their first year by a research orthoptist who carried out a cover test at both distant and near fixation and estimated visual acuity. Those children not available during visits to school were sought out and examined where and when possible, and the coverage thus included private schools and schools for handicapped children.This technique, with a population largely captive in schools, should be and proved to be capable of giving a very high coverage of the population under study. The final total of children screened was 4,784, almost exactly 99 per cent. of the total sample.From the results of this initial examination, a selection was made on the basis of cover test results. Those with certain cover test responses were asked to return for a much more detailed orthoptic investigation and the taking of a full history including a number of questions related to the social copyright.

Strabismus in paediatric age (3-16 year): a clinical study

“…4 Furthermore, current study and the study in England by Adelstein AM et al are hospital based studies while the remaining studies are population based studies. 9 Prevalence of strabismus in current study was found to be 0.3% in boys and 0.299% in girls compared to 7.3% in boys and 6.9% in girls in study by Graham PA. 13 This difference was found to be statistically insignificant. The percentage of girls with strabismus was 49.15% and in boys was 50.85%.…”

Heritability of Strabismus: Genetic Influence Is Specific to Eso-Deviation and Independent of Refractive Error

“…The condition affects 2-6% of the general population and is the most common cause of poor vision in childhood (Graham, 1974;Robaei et al, 2006;Williams et al, 2008). Comitant strabismus is not associated with systemic abnormality and is marked by non-restrictive, non-paralytic ocular misalignment of the same magnitude in all directions of gaze.…”

Interventions for intermittent distance exotropia: review

“…1 Of these, approximately 25% present with exotropia, 2 most commonly intermittent distance exotropia (IDEX). The onset of IDEX is usually between 12 months 3 and 4 years of age and its characteristic features are unique: normal binocular alignment with binocular single vision (BSV) is demonstrable for near fixation, but a constant or intermittent exotropia develops for distance fixation.…”