title: Effect of Cyclopentolate on In Vivo Schlemm Canal Microarchitecture in Healthy Subjects.
abstract: OBJECTIVE
  To characterize the in vivo effect of cyclopentolate on the microstructure of Schlemm canal (SC) in healthy eyes.
  
  
  METHODS
  For healthy subjects, 81 serial horizontal enhanced depth imaging optical coherence tomography B-scans (interval between scans, ∼35 μm) of the nasal corneoscleral limbal area were obtained before and 1 hour after cyclopentolate 1% administration in 1 eye. The structures of aqueous and blood vessels in each scan were used as landmarks to select 50 overlapping scans between the 2 sets of 81 serial scans (before and after cyclopentolate administration). The SC cross-sectional area was measured in each of the 50 selected scans. After 3-dimensional reconstruction, SC volume was determined.
  
  
  RESULTS
  Twelve eyes (12 healthy subjects) were imaged successfully before and after cyclopentolate administration. Mean age was 27.8±4.9 years (range, 25 to 38 y). Following cyclopentolate administration, mean intraocular pressure did not change significantly (13.9±1.5 to 14.2±1.5 mm Hg; P=0.19). Mean SC cross-sectional area decreased by 17%, from 3563±706 to 2959±460 μm (P<0.001). Mean SC volume in the overlapping area (approximately 1.7 mm of circumferential length of SC) decreased from 6,164,061±1,220,787 to 5,119,462±794,763 μm (P<0.001). The decrease in the mean SC cross-sectional area after cyclopentolate administration was greater in eyes with larger baseline SC cross-sectional area (P<0.001, R=0.873).
  
  
  CONCLUSIONS
  Cyclopentolate causes a reduction in SC dimensions in healthy eyes. Future studies are warranted to determine the exact mechanism(s) of this change.
authors.affiliation: *Moise and Chella Safra Advanced Ocular Imaging Laboratory, Einhorn Clinical Research Center, New York Eye and Ear Infirmary of Mount Sinai §Bernard and Shirlee Brown Glaucoma Research Laboratory, Harkness Eye Institute, Columbia University Medical Center ∥Department of Ophthalmology, Manhattan Eye, Ear and Throat Hospital, New York ¶Department of Ophthalmology, Hofstra Northwell School of Medicine, Hempstead, NY †Goldschleger Eye Institute, Sheba Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel ‡George Washington University School of Medicine and Health Sciences, Washington, DC.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Rosman
authors.forename: Alon
authors.initials: A
authors.lastname: Skaat
authors.forename: Jason L
authors.initials: JL
authors.lastname: Chien
authors.forename: Mark P
authors.initials: MP
authors.lastname: Ghassibi
authors.forename: Tarela F
authors.initials: TF
authors.lastname: Sarimiye
authors.forename: Robert
authors.initials: R
authors.lastname: Ritch
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Liebmann
authors.forename: Sung Chul
authors.initials: SC
authors.lastname: Park
mesh_terms: D000328:Adult; D003519:Cyclopentolate / Q000494:pharmacology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007429:Intraocular Pressure; D016850:Limbus Corneae / Q000033:anatomy & histology* / Q000187:drug effects*; D008297:Male; D009184:Mydriatics / Q000494:pharmacology*; D011446:Prospective Studies; D041623:Tomography, Optical Coherence / Q000379:methods; D014065:Tonometry, Ocular
chemical_list: D009184:Mydriatics; D003519:Cyclopentolate