ABSTRACT.Purpose: To examine the incidence, the preoperative findings and the surgical outcome of patients presenting with simultaneous, bilateral retinal detachment. Methods: A retrospective analysis of the medical records of patients undergoing surgery for rhegmatogenous retinal detachment between 1990 and 1998. Results: During this period a total of 827 operations for rhegmatogenous retinal detachment were done in 791 consecutive patients. Eighteen patients (2.3%) had simultaneous, bilateral retinal detachment, giving an annual incidence of 0.35 patients per 100 000 population. They all presented with unilateral symptoms. Compared with the group of unilateral or consecutive, bilateral retinal detachments, patients suffering from simultaneous, bilateral retinal detachments were significantly younger, with a mean age of 40.3 years. Thirteen patients had multiple, round retinal holes associated with lattice degeneration. Sixteen patients were myopic, ranging from ª3 to ª9.25 diopters. The retina was reattached in 35 (97%) of the 36 eyes operated on during the study period. Conclusion: Simultaneous, bilateral retinal detachment is usually found in relatively young, myopic patients with round, atrophic retinal holes, presenting with unilateral visual symptoms.Key words: retinal detachment -bilateral -simultaneous -retinal break -myopia -lattice degeneration -incidence -age -symptoms -surgery. Acta Ophthalmol. Scand. 2000; 78: 354-358 Copyright c Acta Ophthalmol Scand 1999. ISSN 1395-3907 A severe eye disease threatening both eyes is the most challenging situation in ophthalmological practice. This is especially so in the case of vitreoretinal disorders, where bilateral morbidity is the rule rather than a rare exception. In the course of time retinal degenerations or detachment in one eye often necessitate prophylactic or curative treatment of the fellow eye. There are several reports in the literature concerning the frequency of bilateral involvement. Lattice degeneration is present in about 6% of the population and is bilateral in approximately 50% of the affected patients (Glasgow et al. 1993). Among patients with unilateral retinal detachment retinal degenerative changes were found in 63-90% and retinal breaks in about 20% of the undetached fellow eyes (Merin et al. 1971;Ciurlo et al. 1980). According to previous studies, retinal detachment has a strong bilateral tendency, varying from 10 to 20% depending on the criteria of selecting the patients and the length of follow-up (Schepens & Marden 1961;Delaney & Oates 1978;Folk & Burton 1982;. In aphakic detachment series, the risk of bilaterality has been reported to be higher (Benson et al. 1975;Folk & Burton 1983;.The interval between the detachment in the first and second eye usually covers a period of several years (Delaney & Oates 1978). Patients may, however, also present with simultaneous retinal detachment in both eyes at the initial examination. To bring further knowledge on the clinical course of simultaneous, bilateral retinal detachment, an eight-...