Digital Ocular Compressions Reduce Intraocular Pressure in Eyes with Tube Shunts

Précis: Digital ocular compressions decrease intraocular pressure in eyes with tube shunts by significantly greater magnitude and duration when compared to fellow eyes without filtering surgery. Purpose: Digital ocular compressions (DOC) are commonly used by glaucoma surgeons to reduce IOP in the early postoperative period. Little is known, however, about the effects of DOC in eyes with tube shunts. We therefore examined these effects in eyes with long-established, functional glaucoma tube shunts. Methods: In this masked prospective study, adult subjects with primary open angle glaucoma and an Ahmed tube shunt in only one eye were recruited. After obtaining baseline IOP with Goldmann applanation tonometry a single transpalpebral DOC was applied to each eye (in random order). Post-compression IOP was measured after 10, 20, 30, 60, 90, 120, 150, 180, 210, and 240 minutes or until the measured IOP returned to baseline. The fellow (non-surgical) eye was a control. Magnitude and duration of IOP reduction were evaluated using Kaplan-Meier analysis. The pressure applied to eyes in each cohort was standardized via the use of a force-sensitive resistor and impulse was analyzed for differences. Results: 22 eyes of 11 patients underwent DOC. There was no significant difference in the impulse applied to eyes in each cohort (P=0.6). A mean initial IOP reduction of 5.36▒mmHg occurred in tube shunt eyes and 2.55 in control eyes (P=0.014). Log-rank analysis demonstrated longer survival in the tube shunt group (P=0.049). Conclusions: DOC is an effective method for transiently reducing IOP in eyes with long-established, patent tube shunts for about an hour. To maintain this decrease in pressure, compressions will have to be performed on a scheduled basis.