To the Editor.—
In the Multicentre Trial of Cryotherapy for Retinopathy of Prematurity (ROP), the avascular peripheral retina was treated in one of the impaired eyes with "threshold ROP."1 An "unfavorable outcome" was an eye that had a fold of retina through the macula or partial to complete retrolental membrane (grade III through V retrolental fibroplasia).2 Twenty-two percent of the treated eyes had unfavorable results, compared with 43% of the untreated eyes. Not yet reported is the fact that some of the "favorable" eyes with grade II retrolental fibroplasia and grade III retrolental fibroplasia not through the macula will be visually disabled (acuity <20/60) to legally blind (≤20/200). The recommendation to treat only one eye seemed inconsistent with the rationale for stopping the entry of new patients to the study.Drs Phelps and Phelps3 present a complex process for determining treatment of one or both eyes.