The effect of trabeculectomy and glaucoma drainage device implantation on postural intraocular pressure changes in glaucomatous eyes.

PURPOSE: To investigate the effect of trabeculectomy and glaucoma drainage device implantation on posture related intraocular pressure (IOP) changes in glaucomatous eyes. METHODS: Eyes in this prospective study were divided into three groups: those that underwent Ahmed glaucoma valve implantation (Ahmed group), those that underwent trabeculectomy with mitomycin C (trabeculectomy group) and those treated medically (medication group). IOP was measured in the sitting position, and after 15 min in the left lateral decubitus position using a Tonopen XL, and a Goldmann applanation tonometer (GAT). For GAT measurements in the left lateral decubitus position, we used a specialized system comprised of a motorized bed attached to a modified slit-lamp table. RESULTS: 111 eyes of 64 glaucoma patients were included in the analysis: 19 in the Ahmed group, 46 in the trabeculectomy group and 46 in the medication group. The difference in IOP between the sitting and supine positions was significant in the medication (2.23 mmHg) and trabeculectomy (1.48 mmHg) groups, but not in the Ahmed group (0.53 mmHg). This significance was reached with the GAT, but not with the Tonopen. A rise of 5 mmHg or more between the sitting and supine positions was documented in 5.2%, 4.3% and 15.2% of eyes in the Ahmed, trabeculectomy and medication groups, respectively. Intraclass correlation coefficient for IOP measurements in the supine position demonstrated good correlation between the two tonometers. CONCLUSIONS: Ahmed valve surgery significantly reduces postural IOP response as compared with medically treated controls. There was no significant difference between Ahmed valve and trabeculectomy in terms of their effect on the postural IOP change.

Effects of Postural Variation on Intra-ocular Pressure: Comparison between Pseudo-exfoliation Glaucoma and Primary Open Angle Glaucoma.

Purpose: to compare the posture-related intraocular pressure (IOP) changes in pseudo-exfoliation glaucoma (PXFG) and in primary open-angle glaucoma (POAG) patients using the EyeOP, a novel Goldmann Applanation Tonometer (GAT) and to investigate the effect of ab externo trabeculectomy on these changes. Methods: Prospective, non-randomized, controlled, observational study. IOP was measured in sitting and in left lateral decubitus positions (LLDP), using GAT, GAT-EyeOP and Tonopen XL. Main Outcome Measure: Posture-related IOP differences between groups. Results: Thirty-two eyes of 32 PXFG patients (21 non-operated, 11 post-trabeculectomy) and 47 eyes of 47 POAG patients (18 non-operated, 29 post-trabeculectomy) were included. Among non-operated patients, the average increase in GAT IOP between positions (∆IOP) was 2 ± 1.86 mmHg for the PXFG group and 1.9 ± 2.84 mmHg for the POAG group (P = .87). The ∆IOP among operated patients (1.72 ± 1.9) was slightly less than in non-operated (1.6 ± 2.69; P = .905). Generally, in the LLDP, the mean difference between GAT and Tonopen XL IOP measurements was 1.9 ± 3.83 mmHg (r = 0.643; P < .001). A similar correlation was demonstrated between tonometers when measured in the sitting position. Conclusions: Both PXFG and POAG patients have increased IOP in LLDP as compared to an upright position, with no statistically significant difference between groups. Trabeculectomy had no significant effect on the ∆IOP. Abbreviations: PXFG: pseudo-exfoliation glaucoma; POAG: primary open-angle glaucoma; IOP: intraocular pressure; GAT: goldmann applanation tonometer; LLDP: left lateral decubitus position; ∆IOP: average increase in IOP between positions; TM: trabecular meshwork; CCT: central corneal thickness; MMC: Mitomycin C.