Efficacy and safety of hypromellose in ocular implant surgery

In order to assess the efficacy of hypromellose as a viscoelastic substance in cataract surgery with posterior chamber intraocular lens implantation, we studied a series of 88 cases who underwent surgery with either alternate use of a viscoelastic substance (hypromellose, 39 patients, or sodium hyaluronate, 5 patients) or air (44 patients) in the anterior chamber. Endothelial cell loss was least in the group in which air was used (18 +/- 3% cell loss, mean +/- SEM), compared with hypromellose (26 +/- 3%) and sodium hyaluronate (28 +/- 6%), but the difference in percentage cell loss between the groups did not reach statistical significance. Some operative difficulties were encountered in both groups. In both the air and hypromellose groups there were two patients with an early postoperative rise in intraocular pressure, but this was easily controlled, and in both groups there were two patients with postoperative corneal oedema which soon cleared. Visco-elastic substances used in this study were not shown to be superior to air in protecting the corneal endothelium. For this reason use of hypromellose should be confined to situations where its use is likely to confer some special advantage, as in the presence of a bound-down pupil in patient's with chronic glaucoma or perhaps to facilitate "in the bag" implantation.