An eight-year-old child attends your practice for the first time. She is wearing a refractive correction of right and left +1.00DS full-time. Cover testing shows 20 prism dioptre (∆) alternating exotropia at distance, a 15∆ exophoria at near. Monocular visual acuity is 6/5 each eye. She has amplitude of accommodation of 18.00DS with each eye, and near point of convergence 6cm.
She was has been under the care of an ophthalmologist since the age of three but was discharged when she was seven. She has been under the care of an optometrist, never had surgery but has recently moved into your area. The child is concerned about how she looks when her eyes aren’t straight. How would you further investigate and treat this case?
It is important to determine if any exercises have been prescribed in the past and if so what the family’s experience was. I would check the refractive error with a dry refraction and also a cycloplegic refraction to see if there is any latent hyperopia. I would also calculate her distance and near AC/A ratio.
I would measure the size of the distance exotropia without any refractive correction. As long as there was too much more plus I would consider not correcting the distance refractive error. Even with a normal AC/A she has a lot of accommodative amplitude so should be able to cope by accommodating over moderate plus. This should help reduce the size of the distance exotropia and perhaps convert it to a distance exophoria. At near, whether she has symptoms or not I would advise orthoptic exercises so she could get better control at near and this could help with control at distance. The key points for success with eye exercises is to advise a variety (I use three different types at the same time), short periods of exercising (10 minutes) twice a day, parental involvement (helping and encouraging), keeping a journal of how the eyes felt, what days exercises were done, and a review in two weeks in order to check on compliance, offer encouragement and to look for improvement.
If stopping the refractive correction and near eye exercises didn’t reduce the size of the distance deviation enough I would try minus lenses.
Eye exercises for distance exo-deviations, in my experience, probably wouldn’t be successful in this age group although could be considered when the patient is older.