Purpose: To measure monocular visual field extent in very-low birth weight children in whom severe (threshold) acute-phase retinopathy of prematurity (ROP) developed in one or both eyes, and who had random assignment of eyes to cryotherapy or no cryotherapy. A control group of very-low birth weight children in whom ROP did not develop also was tested.
Methods: There were 78 children in the severe ROP group from 5 of 23 centers in the randomized trial of cryotherapy for ROP (CRYO-ROP). The comparison cohort consisted of 75 study participants in whom ROP did not develop. All subjects had birth weights of less than 1251 g. At the 5 1/2-year study examination, visual field size was measured using double-arc kinetic perimetry. Testers were masked to treatment status of each eye. Four meridia were tested: superotemporal (ST), inferotemporal (IT), inferonasal (IN), and superonasal (SN). Target size was 6 degrees.
Results: When blind eyes were assigned a score of 0 degree, the no-ROP, treated, and control eyes had an average visual field extent of 62 degrees, 35 degrees, 27 degrees at ST; 73 degrees, 42 degrees, 35 degrees at IT; 51 degrees, 30 degrees, 21 degrees IN; and 50 degrees, 26 degrees, 22 degrees at SN, respectively. Among 25 children who had bilateral threshold ROP and measurable fields in each eye, values for treated and control eyes were 59 versus 62 at ST, 69 versus 80 at IT, 44 versus 49 at IN, and 41 versus 48 at SN, respectively.
Conclusions: Overall, visual fields in eyes that reached threshold ROP were smaller than those of eyes that did not develop ROP. When only pairs of sighted eyes were considered, visual fields in the treated eyes were 6.4 degrees smaller than those of control eyes. Therefore, it appears that a small loss of peripheral field occurs when cryotherapy prevents the development of retinal detachment.