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.