Vasomotor effect of intravitreal juxta‐arteriolar injection of L‐lactate on the retinal arterioles following acute branch retinal vein occlusion in minipigs

Abstract

Abstract Purpose After branch retinal vein occlusion (BRVO), the retinal territory affected by the occlusion becomes hypoxic and the arterioles crossing this territory are often constricted. The purpose of the current experimental animal study is to investigate the effect of intravitreal juxta‐arteriolar microinjection of L‐lactate on the retinal arteriolar diameter following acute BRVO in minipigs. Methods Under general anesthesia, 9 eyes of 9 minipigs were evaluated. Argon laser endo‐photocoagulation was used to create BRVO. Two hours after BRVO, an intravitreal juxta‐arteriolar microinjection of 50 µl L‐lacate 1 mM (pH=7.4) was performed. The procedure was recorded in real time and retinal arteriolar diameter changes were measured in vivo using a Retinal Vessel Analyzer. Results Two hours after BRVO, the retinal arteriolar diameter decreased from 210 ± 16 AU to 183 ± 14 AU in the affected territories (p=0.04). Five minutes following L‐lactate juxta‐arteriolar microinjection, the retinal arteriolar diameter increased to 241 ± 16 AU (p< 0.01). The vasodilatory effect of L‐lactate persisted and remained significant till the end of the study period (243 ± 15 AU at 30 min, p<0.01). Conclusion We measured a significant vasodilation after intravitreal juxta‐arteriolar L‐lactate microinjection in eyes with experimental BRVO. L‐lactate microinjection can be of potential interest in acute BRVO, reversing the arteriolar vasoconstriction, thus leading to increase of the retinal arteriolar blood flow and possibly to improvement of the retinal cellular function in the occluded territory.