To determine whether intraocular cooling using room-temperature irrigating solution can cause abnormal electroretinograph readings, we operated on six patients with premacular fibrosis and minimal retinal detachment, measuring the temperature in the vitreous cavity and using an electroretinographic monitor. The temperature in the vitreous cavity dropped to 27 degrees C to 28 degrees C after vitrectomies during which room-temperature solutions were used. This resulted in abnormal electroretinograph readings (markedly delayed peak times and reduced amplitudes). These results suggest that the routinely used room-temperature solution affects retinal function during vitrectomy; however, this functional change was reversible in patients having only minimal retinal abnormality.