O F A GROUP of new parasympathomimetic-blocking agents, three appear to be effective cycloplegic drugs suitable for refraction. These compounds are esters of disubstituted acetic acids (Treves and Testa*; Ehrenberg, Ramp, Blanchard, and Treves †). These drugs have been reported as cyclopentolate ‡ (Compound 75 GT), Compound 92 GT and Compound 93 GT. Their usage in 0.5% solution has been previously reported (cyclopentolate, by Priestley and Medine,2 and all three compounds by Gettes and Leopold3 and by Stolzer4). Their cycloplegic efficiency appeared greater than that of homatropine but not quite as great as that of atropine. In addition, they possess the advantage of a shorter duration of activity and an absence of local or systemic reactions. This report concerns the study of the effect of 1% solutions of the same preparations. Two per cent solutions were also employed, but in this concentration these compounds were found to