Abstract
Purpose: :
Comitant esotropia in myopia (CEIM) is characterized initially by diplopia for distance and eventually also for near. It still lacks of a convincing pathogenic explanation and is generally treated surgically with a bimedial recession. Aim of this study was to evaluate the possible role of an accommodative dysfunction as a causative element for CEIM.
Methods: :
Charts from 15 consecutive patients (7 males and 8 females, mean age: 37.5 years, range 21 -48) with CEIM, diplopia only for distance, and refractive overcorrection were retrospectively evaluated. Esotropic deviation ranged between 20 and 50 p.d. In all patients, atropine 1% was prescribed with the following regimen: QD for 3 days and then 1 drop every 5 days for 3 months; afterwards 1 drop every 10 days for 2 months. A near add (sph + 3) was prescribed for 5 months. Patients were checked every two weeks for the first 2 months and then on a bi-monthly basis for a total of two years.
Results: :
Esotropia was reduced gradually in all patients and became intermittent after the first month of treatment. Orthophoria with only distance correction was achieved in all patients after 5 months from the beginning of treatment. Diplopia disappeared between 20 and 40 days after beginning of treatment in all patients in casual seeing conditions. No relapse was observed after two years of follow-up.
Conclusions: :
Prolonged cycloplegia has been shown to eliminate esotropia for distance and diplopia in our group of patients, suggesting that CEIM is caused by an increase of the accommodative demand for near, due to a myopic overcorrection for distance. This in turn triggers more convergence and an accommodative spasm develops. Patients are then unable to relax convergence for distance, with an occurrence of esotropia. With time, esotropia spreads to near vision: at this stage, cycloplegia alone is no more effective and surgery is necessary.
Keywords: esotropia and exotropia • strabismus: etiology • myopia