Surgery for retinal detachment: Authors’ reply

Ophthalmology Volume 106, Number 9, September 1999 alone has not proved particularly useful, as the authors point out. THOMAS R. FRIBERG, MD ANDREW ELLER, MD Pittsburgh, Pennsylvania Authors’ reply Dear Editor: In 1982, Burton1 published his classic article on visual recovery of macula off retinal detachments. He reported a series of 953 cases of retinal detachments, of which 205 patients were able to date the onset of macular involvement. Eighty-seven cases were operated on within the first 9 days of subjective macular symptoms. The first break in his data occurred at day 5 of macular detachment, at which the average level of visual recovery was 20/50. After day 5, visual recovery declined at a rate of 1 Snellen line per week for the next month. In Burton’s study, the recovery of vision within the first 5 days of macular involvement was not studied in detail. There is a general consensus among ophthalmologists that early macula off detachments should be operated on as soon as possible to prevent functional damage. It has been our experience in over 25 years of clinical practice that the recovery of central vision in successful repair of early macula off detachments has not been uniformly satisfying. In some cases where the macula had been off for only 1 or 2 days, the visual results were poor, whereas in others when the macula had been off for 4 –7 days, patients achieved a good visual result. This variation in visual recovery prompted us to perform a prospective study to report on the interaction between the duration of macular detachment within the first week and ultimate visual recovery. Our paper2 reviewed the visual results of 100 patients with macula off detachments of 7 days duration or less. At the time of history taking, the examiner(s) queried the patient as to the loss of central vision with this study in mind. Patients who were uncertain or were judged to have serendipitously become aware of monocular field loss were excluded. With the mean patient age of 59.4 years, we discount Drs. Friberg and Eller’s suggestion that the patients in this age group should be considered unreliable in their histories. Rather, most patients were aware of a dramatic change in their visual status and were able to localize the event to a 24-hour period of the preceding week, particularly when specifically questioned so close to the event. All patients underwent a scleral buckling procedure within 24 hours of presentation. To apply parametric statistical testing, we grouped the patients (pts) into three groups: 1–2 days (30 pts), 3– 4 days (32 pts), and 5–7 days (38 pts) of macular detachment. We had sufficient numbers in each group that we could demonstrate a difference of .28 logmar units between the three groups, or a doubling of the visual angle. This difference was similar to that used in the ETDRS study. Analysis of variance for postoperative visual acuity between the three groups showed a P value of 0.533, which was highly insignificant. The conclusion of our study was that the length of macular detachment within the first week did not

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influence the postoperative visual acuity despite the fact that all patients were operated on within 24 hours of presentation. In Dr. Friberg and Eller’s paper3 on 50 patients with macula off detachments, the potential acuity meter (PAM) was used preoperatively to predict final visual acuity. The authors found that a good PAM result was more significant than a Snellen visual acuity or the duration of retinal detachment by history measured in weeks in predicting postoperative visual recovery. They found no significant linear or nonlinear correlation between the duration of macular detachment in weeks and the ultimate postoperative Snellen visual acuity. In their study, they did not specifically study recovery of vision within the first 7 days of macular involvement. In our study, approximately 60% of patients regained 20/50 or better vision, 35% regained 20/60 –20/200 vision, and 5% were left with less than 20/200 vision no matter when in the first 7 days they presented for surgery. It is our hypothesis that the height of the detachment in the macular region is the most crucial factor in the recovery of postoperative vision in macula off detachments. Patients with very bullous elevated detachments involving the macular region have a poorer visual prognosis for regaining central vision, even if the surgery is performed within 1 to 2 days of presentation. Those with shallow detachments of the macula of longer duration have a better visual prognosis. We are presently conducting a study in which the height of the detachment at the macular region in both the sitting and prone position as measured by ultrasound will be correlated to the ultimate recovery of central vision. We hope that this study will provide definitive data to support our hypothesis. WILLIAM H. ROSS, MD DAVID KOZY, MD Vancouver, BC, Canada References 1. Burton TC. Recovery of visual acuity after retinal detachment involving the macula. Trans Am Ophthalmol Soc 1982;80:475– 97. 2. Ross WH, Kozy DW. Visual recovery in macula-off rhegmatogenous retinal detachments. Ophthalmology 1998;105:2149 – 53. 3. Friberg TR, Eller AW. Prediction of visual recovery after scleral buckling of macula-off retinal detachments. Am J Ophthalmol 1992;114:715–22.

Conjunctival Intraepithelial Neoplasia Dear Editor: Conjunctival intraepithelial neoplasia (CIN) lesions have had a poor cure rate with conventional therapy, and recurrent lesions are frequent. These lesions have been linked to the presence of the human papilloma virus (HPV). Interferons have been found to be beneficial in treating HPV-related mucocutaneous lesions, with minimal side effects.1 In the article by Vann and Karp (Ophthalmology 1999; 106:91–7) complete resolution of CIN lesions in six patients was described after subconjunctival injection and topical application of interferon alfa-2b. “Patients were given a