Amblyopia:referral to ophtalmologists and role of the pediatric vision screening

Key words: Amblyopia, Paediatric screening, Strabismus, Visual acuity

Rationale - Amblyopia is the first cause of monocular vision deficit; in order to limit the damages due to this condition, an early diagnosis is important, because amblyopia is reversible only if treated within a small period of time.
Objectives - The study aims to investigate the modalities and the reasons why children come to ophthalmologists’ attention, the main causes of amblyopia and the importance of the age of referral in relation to the outcome of the treatment.
Materials and methods - The present retrospective study was carried out at the Department of Ophthalmology and Strabology of IRCCS “Burlo Garofolo” in Trieste, Italy and involved 222 patients with a diagnosis of monocular amblyopia, defined as a difference of more than 2/10 between the two eyes in corrected visual acuity. For each patient age at first and last visit, modalities and causes of referral to an ophtalmologist, etiology of amblyopia and type of amblyogenic factor, as well as initial and final visual acuity were examined.
Results - 129 patients (58%) were sent to an ophthalmologist by their paediatricians, 69 (31%) by their parents, 24 patients (11%) through other modalities. The abnormalities found were more frequently visual acuity alterations (41%) and strabismus (36%). The observed causes of amblyopia were: refractive amblyopia (57%), more often due to a hypermetropic anisometropia; strabismic amblyopia (34%), mainly due to constant esotropia; and deprivation amblyopia (9%), more often due to congenital cataract or ptosis. Residual amblyopia (after the treatment) was observed only among patients sent to an ophthalmologist after the age of 6 years. Refractive amblyopia is the most common and less severe. The age of the diagnosis of amblyopia influences significantly the outcome, which is poorer if the pathology is diagnosed after the age of 6 years.
Conclusions - The majority of amblyopic children undergo an ophthalmologic examination between the age of 3 and 4 years, sent by their paediatrician mainly because of visus abnormalities and strabismus; strabismus is usually noticed by parents and can elude paediatricians. For this reason a continuous update on methods of strabismus evaluation is recommended.