On the identification of visual defects in children in general and prematurely born children in particular

Abstract: Aims: Papers I & II: To evaluate the consequences of changes in the criteria for referral to an eye clinic following general pre-school vision screening. According to the former criteria all 4 year old children in the Göteborg area, with visual acuity (VA) <0.8 in either eye, were referred. Since 1992, children with slightly reduced vision (0.65 in each eye or 0.65 in one and 0.8 in the other) are retested at the age of 5.5 years and referred if visual acuity is <0.8. Papers III-V: To investigate visual functions, including visual perception, and ocular morphology in prematurely born children; a group with greatly increased risk of ophthalmologic morbidity and cognitive defects affecting visual performance.Materials and methods:Papers I & II: (I) Children referred to an eye clinic before the alteration of the criteria (n=63) and (II) children tested in the general pre-school screening after the alteration (n=483+123). For children with VA 0.65 in each eye or 0.65 in one and 0.8 in the other at 4 years of age, visual acuity, refraction, orthoptic status, slitlamp examination and ophthalmoscopy were performed, at the age of 4 and 5 years (Paper I) and at 5 years (Paper II). Papers III-V: Evaluation of ophthalmologic status and visual perception was performed on a population-based group of children born before 29 weeks of gestation (Papers III & IV; n=51) and on a group of patients, born before the 37th gestational week (Paper V), in a paediatric eye clinic with known brain lesions or signs that might indicate a brain lesion; strabismus and/or reduced visual acuity (n=91). Ocular fundus photographs were taken and analysed, using digital image analysis, regarding optic disc and retinal vessel characteristics.Results: Papers I & II: At retesting at the age of 5.5 years a majority (>70%) of the children with slightly reduced vision at the age of 4 years had a visual acuity of 0.8 or better. Few had visual defects needing treatment and among those who were treated, the results were good. Papers III-V: Ophthalmologic abnormalities were common in children born before 29 gestational weeks. These children had a smaller optic disc area, neuroretinal rim area and more than normal tortuosity of retinal vessels. Reduced visual perception was observed in 40% of the children born before 29 weeks of gestation and in 67% of children in the patient-based group with brain lesions or signs that might indicate a brain lesion.Conclusions: Papers I & II: The alteration of the screening criteria has resulted in a reduction of unnecessarily referred children while few children in need of treatment are missed. Papers III-V: Prematurely born children are at increased risk for visual problems and ocular abnormalities. Reduced visual perception is common in preterm children even in those without a diagnosis of a brain lesion. Strabismus and subnormal visual acuity in a prematurely born child should alert the ophthalmologist to the possible existence of visual perceptual problems.