PROTECTIVE EFFECTS OF LOCAL HYPOTHERMIA IN VITRECTOMY UNDER FLUCTUATING INTRAOCULAR-PRESSURE

The effects of local hypothermia on the blood-aqueous barrier and reti na were investigated in experimental vitrectomy under wide-ranging flu ctuations of intraocular pressure. After anesthetized albino rabbits h ad undergone closed vitrectomy, their vitreous cavities were continuou sly irrigated for 60 minutes. Perfusion pressures were fluctuated alte rnately between 10 and 80 mmHg. The rabbits were divided into two grou ps in accordance with their intraocular perfusion temperatures: 8 degr ees C and 22 degrees C. Electroretinograms were taken both before and after the irrigation. Protein and prostaglandin E-2 (PGE(2)) concentra tions in the aqueous humor were measured on the 1st and 7th postoperat ive days. Histologic examination was performed on the eyes enucleated on the same days. There were no significant differences in either a- o r b-wave amplitudes between the 8 degrees C and 22 degrees C groups. B oth aqueous protein and PGE(2) concentrations were significantly highe r in the 22 degrees C group than in the 8 degrees C group on the Ist p ostoperative day. Histologically, the ciliary body showed remarkably m ore stromal edema in the 22 degrees C group than in the 8 degrees C gr oup. The severity of the retinal damage did not seem to differ between the two groups. Local hypothermia during vitrectomy under fluctuating intraocular pressure inhibits the breakdown of the blood-aqueous barr ier in the early postoperative stages. (C) 1997 Academic Press Limited .