Genetic epidemiological study of strabismus and congenital cranial dysinnervation disorders in Rawalpindi district

Abstract

Strabismus is an ocular alignment disorder, can affect people of all ages, however congenital forms are common among children. It is characterized by the direction of misalignment and may be latent or manifest, with a variety of etiologies. Its timely diagnosis, classification and treatment are important in pediatric population to limit the occurrence of amblyopia. It is important to understand the development of common strabismus to identify ‘at risk’ populations and implement appropriate treatment. Data on the epidemiology and genetic and phenotypic attributes of strabismus for the metropolitan population of Rawalpindi district are not available. In this context, the present study is a hospital based cross-sectional epidemiological study carried out to determine the prevalence pattern, and clinic-epidemiological and genetic attributes of strabismus in Rawalpindi population. A total of 498 subjects diagnosed with strabismus were recruited from an orthoptics clinic and classified into five subtypes i.e., Esotropia (n=229) > Exotropia (n=158) > Mixed (n=80) > Syndromic (n=19) > Vertical (n=12). The age of the participants has a significant influence on the prevalence of disorder irrespective of their gender. Children in the age range >3 6 were more represented in this cohort. The left eye is more vulnerable to esotropia (n=58), and the action of inferior oblique muscle was found to be the most common insult (n=101). Refractive error was an important determinant of strabismus with astigmatism (24%) being most common among patients with esotropia. Sporadic cases constituted 75% of all patients. Consanguinity, caesarian delivery, positive family history and premature birth were significant risk factors. This study is a pilot epidemiological approach to investigate relative pattern and incidence of strabismus subtypes and may bridge the gaps in the current knowledge of the cause and consequences of the disease. This will also be helpful for health management authorities to plan and build optometry centers for such patients. Further research on molecular genetic level could help to identify hereditary links in strabismus subtypes and locate causative genes to aid the understanding of strabismus development.