title: Real-Time Monitoring of Suprachoroidal Space (SCS) Following SCS Injection Using Ultra-High Resolution Optical Coherence Tomography in Guinea Pig Eyes.
abstract: OBJECTIVE
  To monitor the change of suprachoroidal space (SCS) using ultra high resolution-optical coherence tomography (UHR-OCT) following SCS injection with different drug formulations.
  
  
  METHODS
  An amount of 10 or 20 μL of saline or indocyanine green (ICG) or triamcinolone acetonide (TA) suspension (40 or 80 mg/mL) was injected suprachoroidally into the guinea pig eye with a 30-gauge needle. Immediately after injection, the eyes were imaged by UHR-OCT from 60 minutes up to 24 hours. At each time point, the SCS area on each OCT cross-section was measured in pixels with Image J and the area change from the baselines was analyzed over time.
  
  
  RESULTS
  A 20-μL injection produced 130% to 200% SCS expansion compared to a 10-μL injection for saline and TA suspension (P < 0.01). After SCS injection, the time that expansion persisted was formulation dependent. Thus, expansion in response to injection of TA suspension, ICG, and saline persisted for 24 hours, 180 minutes, and 60 minutes, respectively. Moreover, ICG injection produced a significantly larger area of distribution in the SCS than the TA suspension (0.626 vs. 0.275 cm(2), P < 0.0001).
  
  
  CONCLUSIONS
  The SCS is expandable and can recover to preinjection status after injected fluid is cleared by physiological processes. The injection-induced SCS expansion is volume-dependent, and the drug/dye retained in the SCS is formulation-dependent. The current injection technique with a volume of 20 μL or less is well tolerated in guinea pig eyes.
authors.affiliation: Institute of Ocular Pharmacology, School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Gu
authors.affiliation: Institute of Ocular Pharmacology, School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Jinkun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Institute of Ocular Pharmacology, School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Li
authors.affiliation: Institute of Ocular Pharmacology, School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: QingKai
authors.initials: Q
authors.lastname: Ma
authors.affiliation: Institute of Ocular Pharmacology, School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Meixiao
authors.initials: M
authors.lastname: Shen
authors.affiliation: Institute of Ocular Pharmacology, School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China 2Jacob's Retina Center at Shiley Eye Institute, Department of Ophthalmology, University of California San Diego, La Jolla, Califo.
authors.forename: Lingyun
authors.initials: L
authors.lastname: Cheng
mesh_terms: D000818:Animals; D002829:Choroid / Q000473:pathology* / Q000503:physiopathology; D004195:Disease Models, Animal; D005110:Extracellular Space; D006168:Guinea Pigs; D007208:Indocyanine Green / Q000008:administration & dosage; D056965:Injections, Intraocular / Q000009:adverse effects*; D007429:Intraocular Pressure; D041623:Tomography, Optical Coherence / Q000379:methods*; D014222:Triamcinolone Acetonide / Q000008:administration & dosage
chemical_list: D014222:Triamcinolone Acetonide; D007208:Indocyanine Green