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Article
April 1996

Multicenter Trial of Cryotherapy for Retinopathy of PrematuritySnellen Visual Acuity and Structural Outcome at 5½ Years After Randomization

Author Affiliations

From the Casey Eye Institute, Oregon Health Sciences University, Portland. The authors have no affiliation with or financial interest in the subject matter or materials discussed in the article (eg, employment, consultancies, stock ownership, honoraria), with the exception of Velma Dobson, PhD, who receives a small royalty from the sale of Teller Acuity Cards. A complete list of the members of the Cryotherapy for Retinopathy of Prematurity Cooperative Group appears in a box on pages 420 and 421.

Arch Ophthalmol. 1996;114(4):417-424. doi:10.1001/archopht.1996.01100130413008
Abstract

Objective:  To evaluate outcome at 5½ years after randomization in eyes that underwent cryotherapy and in control eyes of patients in the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity.

Design:  During infancy, patients with bilateral threshold retinopathy of prematurity (ROP) were assigned to receive cryotherapy for one eye and no cryotherapy for the other eye. Those with threshold ROP in only one eye (asymmetric) were randomly assigned to cryotherapy or no cryotherapy for that eye. Then, 5½ years later, testers who were masked to the treatment status of each eye measured the patients' monocular visual acuity by using the log of the minimum angle of resolution visual acuity chart that was used in the Early Treatment Diabetic Retinopathy Study. This was the most refined visual acuity testing yet performed on this cohort. Structural outcome was evaluated by participating ophthalmologists' assessment of ROP residua in the posterior pole of the fundus.

Patients:  Patients were 291 children who had been preterm infants with birth weights of less than 1251 g in whom threshold ROP had developed. Two hundred forty patients had bilateral threshold ROP, and 51 had threshold ROP in only one eye.

Results:  For the 234 children examined, both visual acuity and fundus structure showed a reduction in unfavorable outcomes in treated vs control eyes: 47.1% vs 61.7%, respectively (P<.005), for visual acuity and 26.9% vs 45.4%, respectively (P<.001), for fundus status. Detailed analysis of visual acuity outcomes for all eyes revealed that while fewer treated eyes (31.5%) than control eyes (48%) were blind (P<.001), there was a slight trend toward fewer eyes with a visual acuity of 20/40 or better in the treated (13%) vs control (17%) groups (P=.19).

Conclusions:  The results support the long-term efficacy and safety of cryotherapy in the treatment of severe ROP. However, the data show preliminary evidence of a possible adverse effect of this treatment on visual acuity.

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