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- Title
Effect of Pilocarpine Hydrochloride on the Schlemm Canal in Healthy Eyes and Eyes With Open-Angle Glaucoma.
- Authors
Skaat, Alon; Rosman, Michael S.; Chien, Jason L.; Mogil, Rachel S.; Ren, Ruojin; Liebmann, Jeffrey M.; Ritch, Robert; Sung Chul Park; Park, Sung Chul
- Abstract
<bold>Importance: </bold>The in vivo effect of pilocarpine hydrochloride on the Schlemm canal may help explain its pharmacologic mechanism of action and better indicate its clinical use.<bold>Objective: </bold>To investigate the effect of pilocarpine on the structure of the Schlemm canal in vivo in healthy eyes and eyes with glaucoma.<bold>Design, Setting, and Participants: </bold>In this case-control study, healthy individuals and patients with open-angle glaucoma were prospectively enrolled between September 1, 2013, and June 30, 2014, after a complete ophthalmologic examination at a tertiary glaucoma referral practice. Eighty-one serial, horizontal, enhanced depth imaging optical coherence tomographic B-scans (interval between B-scans, approximately 35 µm) of the nasal corneoscleral limbus were performed before and 1 hour after topical administration of pilocarpine, 1%, in 1 eye of healthy volunteers and pilocarpine, 2%, in 1 eye of patients with glaucoma. Fifty B-scans in the overlapping area (circumferential length, approximately 1.7 mm) between the 2 sets of serial scans (before and after pilocarpine administration) were selected for analysis based on the structures of aqueous and blood vessels as landmarks. The cross-sectional area of the Schlemm canal was measured in each selected B-scan. Volume of the Schlemm canal was calculated using commercially available 3-dimensional reconstruction software.<bold>Main Outcomes and Measures: </bold>Mean cross-sectional area of the Schlemm canal.<bold>Results: </bold>Enhanced depth imaging optical coherence tomographic scans of the Schlemm canal were performed successfully before and after administration of pilocarpine, 1%, in 9 healthy eyes (9 individuals) and pilocarpine, 2%, in 10 eyes with glaucoma (10 patients) (mean [SD] age, 31.9 [7.8] and 68.7 [13.2] years, respectively). Following pilocarpine administration, mean (SD) intraocular pressure decreased from 14.3 (1.3) to 13.7 (1.1) mm Hg in healthy eyes (P = .004) and from 17.5 (6.0) to 16.6 (6.1) mm Hg in eyes with glaucoma (P = .01). The mean (SD) cross-sectional area of the Schlemm canal increased by 21% (4667 [1704] to 5647 [1911] µm2) in healthy eyes (P < .001) and by 24% (3737 [679] to 4619 [692] µm2) in eyes with glaucoma (P < .001) (mean difference in percent increase, 2.2%; 95% CI, -8.5% to 12.9%). The mean (SD) volume of the Schlemm canal in the overlapping area increased from 8 004 000 (2 923 000) to 9 685 000 (3 277 000) µm3 in healthy eyes (P < .001) and from 6 468 000 (1 170 000) to 7 970 000 (1 199 000) µm3 in eyes with glaucoma (P < .001).<bold>Conclusions and Relevance: </bold>These data suggest that pilocarpine expands the Schlemm canal in eyes with and without glaucoma. No differences in the effect were identified between the 2 groups. Enhanced depth imaging optical coherence tomography may be useful in investigating the effect of pharmacologic agents on the Schlemm canal.
- Subjects
GLAUCOMA diagnosis; RESEARCH; INTRAOCULAR pressure; GLAUCOMA; VISUAL fields; SCHLEMM'S canal; RESEARCH methodology; ANTERIOR eye segment; MIOTICS; RETROSPECTIVE studies; EVALUATION research; PILOCARPINE; OPHTHALMIC drugs; COMPARATIVE studies; RANDOMIZED controlled trials; OPTICAL coherence tomography; TONOMETRY; LONGITUDINAL method
- Publication
JAMA Ophthalmology, 2016, Vol 134, Issue 9, p976
- ISSN
2168-6165
- Publication type
journal article
- DOI
10.1001/jamaophthalmol.2016.1881