Reappraisal of occlusion therapy for severe structural abnormalities of the optic disc and macula.

The visual function of some children with structural defects of the macula or optic nerve has previously been shown to improve with occlusion therapy. The charts of five children, ages 4 to 8 years, who had various types of severe structural abnormalities were reviewed. Two patients had optic nerve hypoplasia; there was one case each of foveal hypoplasia, posterior persistent hyperplastic primary vitreous, and retinopathy of prematurity. All the patients had undergone extensive amblyopia therapy prior to referral. In three children, occlusion therapy had been initiated and continued intensively for several months or longer without recognizing the presence of a severe, underlying structural abnormality. In none of the five children was there any clear-cut evidence of visual improvement. In some cases, the long period of enforced iatrogenic vision impairment resulted in significant psychosocial harm and developmental delay. In all five cases, it was structural changes rather than amblyopia that ultimately accounted for visual loss. The authors stress the importance of a meticulous fundus examination directed at finding organic defects prior to patching. Close, periodic monitoring of visual function should then follow. To spare the child unnecessary psychosocial impairment, it is advisable to follow established recommended thresholds for terminating occlusion therapy.