The role of viscoelastics, cannulas, and irrigating solution additives in post-cataract surgery corneal edema: a brief review.

Corneal clarity is dependent upon maintenance of the corneal endothelial barrier and pump. Mechanical trauma is usually considered to be the most significant factor in corneal endothelial damage during cataract surgery resulting in postoperative corneal edema. However, corneal decompensation out of proportion to the degree of trauma seen during surgery does occur. These cases of unexpected corneal edema can often be traced to unrecognized preoperative endothelial dysfunction or to toxicity of intraocular medications used during surgery. This paper reviews the role of viscoelastics in reducing surgical trauma, their toxicity, and the risks of toxicity inherent in the use of re-usable cannulas and irrigating solution additives. Disposable cannulas should be used whenever possible. The use of re-usable cannulas with viscoelastics is highly likely to result in toxic residues being introduced onto the eye, and must be avoided. Irrigating solution additives should be tested with in-vitro human donor cornea perfusions prior to clinical use.