We have found a global bilateral retinal detachments (R.D.) rate of 15,52% over a population of 1148 patients. 60% of these bilateral R.D. have been seen by us for the first time at the moment of the detachment of the second eye. The actual percentage of R.D. on a second eye that was free of any R.D. at the first examination is 3,5% only, and it climbs to 4,45% if we consider only the second eyes harboring dangerous peripheral retinal lesions. This result compares favourably to the 10% to 20% second eye R.D. rate in the absence of preventive treatment; it has been obtained through a systematic prophylaxy of all retinal breaks and almost all lattice, snowflake, and schisis by cryoapplication or xenon photocoagulation or mostly argon laser photocoagulation. In the absence of any peripheral retinal lesion systematic equatorial argon laser circular photocoagulations can be useful.