Lens-sparing vitrectomy for IV retinopathy of prematurity provides a good anatomic success rate and achieve good visual acuity success rates. Forty-two weeks postmenstrual age seems to be the ideal time for surgery.
"Previously, a 4A retinal detachment heralded a downward spiral and possibly a very poor outcome. Now, however, surgery to treat a 4A retinal detachment represents an opportunity for effective intervention in these patients," Dr. Trese said.
The peak incidence of retinal detachment, as described by David Coats, MD, is at 41 weeks postmenstrual age.
The Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) Study established the natural history of the disease. When children with stage 4A ROP at 40 weeks postmenstrual age were assessed at the age of 4.5 years, the anatomic results indicated that 85% of the eyes had macular involvement, and 15% did not; 50% of those had unfavorable outcomes. The visual results showed that 76% were blind with either light perception vision, no light perception, or very low vision; only 10% had 20/40 or better vision, Dr. Trese recounted.
He and his colleagues conducted a study of 4A ROP in which there were nine ROP sectors, which are clock hours that are superimposed on the three retinal zones.
"The active disease was gauged by the age of the children, who were under 50 weeks postmenstrual age. Based on the data from the CRYO-ROP Study, 92% of these eyes would progress to stage 5 ROP. The goal of this study was to preserve the normal macular anatomy," he explained.
All patients underwent a two-port lens-sparing vitrectomy. Only one surgery was performed, and during this procedure the lenses in these children did not seem to be greatly affected postoperatively. Anisometropia was not induced. Dr. Trese and colleagues reported in 2001 an anatomic success rate of 90%.
"The advantage of this surgery is that it deals directly with the tractional problems," he said.
To assess the visual outcomes of children with stage 4A retinal detachment, Dr. Trese and colleagues retrospectively reviewed a consecutive series of patients referred to Associated Retinal Consultants.
The children all underwent lens-sparing vitrectomy. Prior to that, the stage of the detachment was determined during an examination. The visual acuity levels were determined using Teller Acuity Cards or Allen Cards. The investigators evaluated 45 eyes of 39 patients. Twelve eyes of 11 patients were eventually lost to follow-up, for a total of 33 eyes of 28 patients that could be evaluated. Twenty-three eyes of 20 children underwent repair of a retinal detachment and visual acuity measurement. These children were an average of 668 grams at birth and an average of 26 weeks gestational age. The postmenstrual age at surgery was 43.7 weeks.
Dr. Trese reported that 90% had an anatomic attachment, and 83% had a macula that appeared normal on clinical examination. The average age at the time of testing was 3.5 years. The average logMAR acuity was 20/58; 70% of the eyes had a visual acuity of 20/80 or better, and the remainder had an average between 20/100 and 20/200.
"About half of the children ultimately had 20/40 or better vision. Compared with the natural history of the disease, there is a dramatic difference in number of children who were blind or legally blind compared with those who had 20/80 or better vision," Dr. Trese emphasized. When the investigators looked at a comparison of the children with an average of 20/40 vision and the natural history, the difference was "quite dramatic."
Most of the children in the study could undergo visual acuity testing; however, a small number could not be tested, and this was considered a limitation of the study.
"Lens-sparing vitrectomy for 4A ROP provides a good anatomic success rate and can achieve good visual acuity success rates. The best surgical results are obtained in the eye with quiet vasculature, which application of laser can create. Forty-two weeks postmenstrual age seems to be the ideal time for surgery," he concluded.