Comparação de métodos de medida da acuidade visual em crianças e caracterização do rastreamento e diagnóstico da ambliopia no serviço de estrabismo do Hospital São Geraldo HC/UFMG

Abstract

Introduction: Amblyopia is one of the main causes of preventable blindness in children and can be defined as low visual acuity (VA) due to the lack of adequate retina stimulation during critical period of the infant eyesight development. Measuring children VA as early as possible is particularly important for diagnosing and treating amblyopia. A comparative study between different VA exams in pediatric ophthalmology could determine the most suitable tests for infant visual screening programs in public health for early amblyopia diagnosis. Purpose: Compare children VA tests at an university hospital in the strabismus sector. Characterize amblyopia regarding screening and diagnosis in this population. Method: Sample population of 85 children, in between 0 to 12 years old, were divided into 3 groups according to verbalization and literacy. Each group was subjected to specific VA tests: Teller Acuity Cards, Induced Tropia Test and Clinical judgment (group 1); LH chart and Tumbling E chart (group 2); and Early Treatment Diabetic Retinopathy Study (ETDRS) chart for near and far acuity and Snellen letters chart (group 3). At the end it was determined amblyopia prevalence, mean age of the first ophthalmological evaluation and main causes and risk factors of amblyopia in the sample population. Results: The Tumbling E test showed high accuracy (87.50%) but reduced sensitivity (77.78%) in comparison with the gold standard examination, LH. The Snellen chart had an accuracy (93.33%) greater than the near ETDRS chart (82.93%), when compared to the far ETDRS chart, used as the gold standard. For group 1 the small amount data of patients made unfeasible to evaluate the ideal diagnostic tests. The tests showed a good correlation between the VA values in logMar. The median age of the first ophthalmological evaluation was 30.00 (12.00; 48.00) months. Only 1% of infants had their first consultation performed before the first year and 51% were evaluated only after the third year. The amblyopia prevalence was 39.3%. Data shows that the main cause of amblyopia was strabismus (90.3%) and the second cause was refractive (28.9%). Data points that the only proven risk factor associated with amblyopia was congenital cataract. Conclusions: Detection accuracy for amblyopia was high in the Tumbling E and Snellen charts in comparison to the gold standard tests, LH and ETDRS. For the near ETDRS chart the accuracy was bellow expectation, nevertheless it is still a good method for amblyopia diagnosis. Teller and LH method showed to be significantly more time consuming than the others. LH, ETDRS and Teller Acuity Cards are costly when compared to the others. Application difficulty was greater in the Teller Acuity Cards test and the Tumbling E was the most difficult for children understanding. Higher amblyopia prevalence in this service compared to data from the general pediatric population is justified by specialized sector in treatment of this clinical condition.