title: Measurement of choroidal perfusion and thickness following systemic sildenafil (Viagra(®) ).
abstract: OBJECTIVE
  To demonstrate anatomic and physiologic changes in the human choroid following systemic sildenafil citrate (Viagra®) using enhanced depth imaging spectral domain-optical coherence tomography (EDI-OCT) and swept-scan high-frequency digital ultrasound.
  
  
  METHODS
  Seven healthy male subjects (mean age 32.7 years) were evaluated at baseline and 2 hr after ingesting 50 mg of sildenafil. Swept-scan high-frequency digital ultrasound and EDI-OCT were utilized to measure choroidal perfusion and thickness, respectively. Results were read by masked observers. The Wilcoxon signed-rank test and t-test were used to analyse differences in choroidal flow and thickness at baseline and 2 hr after ingestion of sildenafil.
  
  
  RESULTS
  Two hours following sildenafil, increased choroidal perfusion was observed in 11 of 12 eyes measured by swept-scan high-frequency digital ultrasound. The mean increase was 3.46 (±2.00) times baseline with a range of 0.47-7.80 times baseline (p = 0.004). Increased choroidal thickness was observed in 12 of 12 eyes measured with EDI-OCT. The average choroidal thickness increased by 11.6% temporal to the fovea, 9.3% nasal to the fovea and 10.7% underneath the fovea (p < 0.001 for all values).
  
  
  CONCLUSIONS
  Choroidal perfusion and thickness both increase in response to systemic sildenafil. These changes could secondarily affect retinal function, explain previously reported clinical symptoms and potentially be a useful adjunct for treatment of ocular diseases that would benefit from increased choroidal blood flow.
authors.affiliation: Department of Ophthalmology, Weill Cornell Medical College, New York City, NY, USA.
authors.forename: David Y
authors.initials: DY
authors.lastname: Kim
authors.forename: Ronald H
authors.initials: RH
authors.lastname: Silverman
authors.forename: Robison Vernon Paul
authors.initials: RV
authors.lastname: Chan
authors.forename: Aziz A
authors.initials: AA
authors.lastname: Khanifar
authors.forename: Mark
authors.initials: M
authors.lastname: Rondeau
authors.forename: Harriet
authors.initials: H
authors.lastname: Lloyd
authors.forename: Peter
authors.initials: P
authors.lastname: Schlegel
authors.forename: Donald Jackson
authors.initials: DJ
authors.lastname: Coleman
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D002829:Choroid / Q000033:anatomy & histology* / Q000098:blood supply*; D006801:Humans; D008297:Male; D010879:Piperazines / Q000008:administration & dosage*; D011687:Purines / Q000008:administration & dosage; D012039:Regional Blood Flow / Q000502:physiology; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000008:administration & dosage*; D041623:Tomography, Optical Coherence; D014665:Vasodilator Agents / Q000008:administration & dosage*
chemical_list: D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014665:Vasodilator Agents; D000068677:Sildenafil Citrate