Effect of Ca 2+-free and Mg 2+-free BSS Plus solution on the retinal pigment epithelium and retina in rabbits

Abstract

PURPOSE: To determine whether intravitreal irrigation with Ca 2+-free and Mg 2+-free BSS Plus (Alcon Laboratory, Fort Worth, Texas) solution alters the adhesiveness between the retinal pigment epithelium and the retina of rabbits. METHODS: Thirty-four eyes of 34 Dutch pigmented rabbits underwent lensectomy and vitrectomy. Subsequently, the vitreous cavity of 24 eyes was irrigated with Ca 2+-free and Mg 2+-free BSS Plus solution for 10 or 20 minutes. The other 10 eyes were irrigated with BSS Plus solution for 20 minutes as controls. To determine the adhesiveness between the retinal pigment epithelium and retina, a retinal detachment was produced in 12 of the 34 eyes. The apical surface of the retinal pigment epithelium and the photoreceptor outer segments were examined by scanning electron microscopy. Retinal physiology was assessed by electroretinography and retinal morphology by light microscopy. RESULTS: After retinal detachment was produced, the number of cone sheaths on the apical surface of the retinal pigment epithelium after irrigation with Ca 2+-free and Mg 2+-free BSS Plus solution for 20 minutes (33 ± 15, mean ± SD) was significantly less than the number of cone sheaths on the apical surface of the retinal pigment epithelium of eyes after irrigation with BSS Plus solution for 20 minutes (120 ± 50) or the number of cone sheaths on the apical surface of the retinal pigment epithelium of eyes after 10 minutes of irrigation with Ca 2+-free and Mg 2+-free BSS Plus solution (115 ± 49; P = .02). The b-wave amplitudes in the eyes irrigated with Ca 2+-free and Mg 2+-free BSS Plus solution for 20 minutes were depressed compared with the b-waves in eyes irrigated with BSS Plus solution for 20 minutes on the first postoperative day ( P = .03). After the third postoperative day, there was no significant difference in the b-waves ( P > .06). Light microscopy demonstrated no morphologic abnormalities after the use of both solutions. CONCLUSIONS: Intravitreal irrigation with Ca 2+-free and Mg 2+-free BSS Plus solution for 20 minutes altered the adhesion between the retinal pigment epithelium microvilli and retinal outer segments and made the creation of retinal detachment less traumatic. These results suggest that Ca 2+-free and Mg 2+-free BSS Plus solution may be of clinical value for the creation of an intentional retinal detachment for foveal translocation surgery.