Prevention of strabismic amblyopia of early onset with special reference to the optimal age for screening

Of 78 consecutive cases with constant unilateral esotropia diagnosed during screening and treated from the ages of seven months to three years, 82% ended up with visual acuity of 6/12 or better toward end of active treatment at the age of six to eight years. Of the cases with visual acuity of 6/12 or better at the end of treatment, 59% retained their vision when re-examined four to ten years later. The most important single parameter for the achievement of normal visual acuity was age of onset of treatment below two years and for long-term stability of the result this age dropped to 18 months. Initial large angles of esotropia had better prognosis probably because they were associated with an earlier onset of treatment. Poor prognosis was associated with faulty or no fixation of the esotropic eye when first diagnosed, with the failure to achieve alternation and with marked ansiometry. The optimal age for screening for strabismic amblyopia was suggested to be 12-18 months.