Intraocular Pressure and the Intrastromal Corneal Ring

The intrastromal corneal ring is a refractive surgery device placed in the peripheral cornea at 2/3 depth, and it has the potential to correct both myopia and hyperopia. This study examined whether intraocular pressure (IOP) could be accurately measured with the ring in place and whether intraocular pressure was altered as a result of surgery. Fifteen eye bank eyes were attached to a manometric device to control pressure (10 to 40 mm Hg) which was measured over the range before and after placement of the ring with a pneumotonometer. A paired t-test showed no significant difference in pressure, pre- vs postoperative. To determine the effect of the ring on IOP in vivo, ring implantation was performed on 10 rabbit eyes and pressure measured before and after surgery. At 24 and 48 hours postoperatively, there was no significant change in IOP (3 +/- 2 mm Hg, P greater than .05, and 9 +/- 8 mm Hg, P greater than .20 respectively) and facility of outflow calculated from tonography showed no significant change.