Effect of argon laser photocoagulation on fluorescein transport across the blood-retinal barrier

The effect of argon laser photocoagulation on the active transport of fluorescein across the blood-retinal barrier was examined in the rabbit, before and after healing of the photocoagulation scars.The outward fluorescein transport across the blood-retinal barrier, which was assessed by vitreous fluorophotometry after intravitreal administration of sodium fluorescein, was greatly reduced in the first days after panretinal photocoagulation with the argon laser. However, this alteration of the barrier recovered progressively with time, depending on the intensity of the photocoagulation burns. When moderate panretinal laser photocoagulation was used (500 μm, 0·1 sec, 0·1 W), the transport activity was markedly altered by 6 days, but there was almost complete recovery at the end of 30 days. When severe photocoagulation was performed (500 μ, 0·1 sec and 0·25–0 · 35 W), very little recovery was observed, even 90 days afterwards.