Effects of ocular hypothermia: potential perspectives in vitreoretinal surgery

Purpose: To summarize knowledge about the effects of experimental and iatrogenic hypothermia on ocular structures, with a specific focus on retinal consequences and therapeutical perspectives in vitreoretinal surgery. Materials and methods: This review of the literature includes a section on the effects of low temperature on different ocular structures (sclera, choroid, retina, vitreous and ciliary body), a focus on the effect on retinal pigment epithelium (RPE), retinal neurons and inflammation and a section about results of vitreoretinal surgery performed at low temperature. In vitro, animal and human studies were included. Results: Temperature changes induce several regulatory responses within the eye, including modifications of intraocular pressure (IOP), local blood flow, cytokine secretion and cellular metabolism. Cooling of retinal structures has been demonstrated to induce beneficial effects including increased survival of RPE and retinal neurons. Vitreoretinal surgery performed at lower intraocular temperatures has shown positive effect on postoperative inflammation, even though the rebound effect of a sudden postoperative temperature increase seems to be detrimental. Conclusions: Despite being a promising approach, vitreoretinal surgery performed under lower intraocular temperature conditions deserves refinement in its methodologies. Hopefully, new randomized clinical trials will provide indications on how to apply this technique in the safest and most effective way.