Randomised controlled trial of treatment of unilateral visual impairment detected at preschool vision screening

Abstract

Objectives To test the efficacy of treatment for unilateral visual loss detected by preschool vision screening and the extent to which effectiveness varies with initial severity. Design Randomised controlled trial of full treatment with glasses and patching, if required, compared with glasses only or no treatment. Masked assessment of best corrected acuity after one year of follow up. Setting Eight UK eye departments. Participants 177 children aged 3-5 years with mild to moderate unilateral impairment of acuity (6/9 to 6/36) detected by screening. Results Children in the full and glasses treatment groups had incrementally better visual acuity at follow up than children who received no treatment, but the mean treatment effect between full and no treatment was equivalent to only one line on a Snellen chart (0.11 log units; 95% confidence interval 0.050 to 0.171; P < 0.0001). The effects of treatment depended on initial acuity: full treatment showed a substantial effect in the moderate acuity group (6/36 to 6/18 at recruitment) and no significant effect in the mild acuity group (6/9 to 6/12 at recruitment) (P = 0.006 for linear regression interaction term). For 64 children with moderate acuity loss the treatment effect was 0.20 log units, equivalent to one to two lines on a Snellen chart. When all children had received treatment, six months after the end of the trial, there was no significant difference in acuity between the groups. Conclusions Treatment is worth while in children with the poorest acuity, but in children with mild (6/9 to 6/12) unilateral acuity loss there was little benefit. Delay in treatment until the age of 5 did not seem to influence effectiveness.

Health visitor referrals to secondary vision screening clinic: a 5-year review

“…The current referral criterion used is VA of less than 6/9 in one or both eyes. A trial of treatment of unilateral visual impairment detected at pre-school vision screening 4 concluded that children with 6/9 or 6/12 vision in one eye (and normal vision in the other) benefited little from treatment. As testing on pre-school children is often less reliable than that on school-age children, it was felt that 6/9 is within the normal range of VA on a crowded test and therefore this referral criterion currently remains our standard.…”

Relationship Between Anisometropia, Patient Age, and the Development of Amblyopia

“…74,75,103 The visual acuity data in this study were obtained at the first visit, prior to any such period of spectacle wearing. Thus, many of the patients identified as having amblyopia in this study could potentially have been treated with spectacles alone and still had substantial improvement in acuity.…”

“…71 This may also explain why many patients who have anisometropic amblyopia respond simply to spectacles alone, [73][74][75] and why patients with anisometropic amblyopia are more likely to improve at later periods in life. 75 …”

Screening amblyopia of preschool children with uncorrected vision and stereopsis tests in Eastern Taiwan

“…Screening and treatment at preschool age, when it is a sensitive period of visual development, lead to a better visual outcome. [8][9][10] However, screening for amblyopic children is labour-intensive, costly, and sometimes unreliable. [11][12][13][14] This situation is more evident in eastern Taiwan where a mixed population of mountain aborigines and Han Taiwanese people is scattered from mountains to coasts.…”