title: Conjunctival microvascular haemodynamics in sickle cell retinopathy.
abstract: OBJECTIVE
  To determine alterations in bulbar conjunctival microvascular haemodynamics in sickle cell retinopathy (SCR) subjects with focal macular thinning (FMT).
  
  
  METHODS
  Conjunctival microcirculation imaging and spectral domain optical coherence tomography (SD-OCT) were performed in 22 subjects (eyes) diagnosed with SCR. Based on evaluation of SD-OCT retinal thickness maps, eyes were assigned to one of the two groups: with or without FMT. Conjunctival venular diameter and axial blood velocity were measured in multiple venules in each eye by customized image analysis algorithms. Measurements were then categorized into two vessel size groups (vessel size 1 and 2) and compared between FMT groups. A Pearson correlation coefficient was computed to assess the relationship between retinal thickness and axial blood velocity.
  
  
  RESULTS
  Mean age, haematocrit, sickle cell haemoglobin type and median retinopathy score were not significantly different between the two groups (p ≥ 0.1). Retinal thickness in parafoveal and perifoveal temporal subfields was significantly lower in eyes with FMT as compared to eyes without FMT (p ≤ 0.04). There was a significant effect of FMT on axial blood velocity (p = 0.04), while the effect of vessel size was not significant (p = 0.4). In vessel size 1, axial blood velocity was lower in eyes with FMT than in eyes without FMT (p = 0.03), while in vessel size 2, there was no statistically significant difference between FMT groups (p = 0.1). In vessel size 1, there was a significant positive correlation between axial blood velocity and retinal thickness in the perifoveal (r = 0.48, p = 0.02) and parafoveal (r = 0.43, p = 0.04) temporal subfields.
  
  
  CONCLUSIONS
  Conjunctival axial blood velocity in small venules is reduced in SCR subjects with focal macular thinning.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, USA.
authors.forename: Ali
authors.initials: A
authors.lastname: Kord Valeshabad
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Wanek
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, USA.
authors.forename: Ruth
authors.initials: R
authors.lastname: Zelkha
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, USA.
authors.forename: Jennifer I
authors.initials: JI
authors.lastname: Lim
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, USA.
authors.forename: Nicole
authors.initials: N
authors.lastname: Camardo
authors.affiliation: Department of Ophthalmology, Loyola University Medical Center, Chicago, Illinois, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Gaynes
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, USA.
authors.forename: Mahnaz
authors.initials: M
authors.lastname: Shahidi
mesh_terms: D000328:Adult; D000755:Anemia, Sickle Cell / Q000503:physiopathology*; D001783:Blood Flow Velocity / Q000502:physiology; D003228:Conjunctiva / Q000098:blood supply*; D006439:Hemodynamics; D006450:Hemoglobin SC Disease / Q000503:physiopathology*; D006801:Humans; D008833:Microcirculation; D008875:Middle Aged; D011446:Prospective Studies; D012164:Retinal Diseases / Q000503:physiopathology*; D041623:Tomography, Optical Coherence; D014699:Venules / Q000503:physiopathology
keywords: bulbar conjunctiva; haemodynamics; retina; sickle cell disease