title: The functional significance of foveal abnormalities in albinism measured using spectral-domain optical coherence tomography.
abstract: OBJECTIVE
  The relationship between foveal abnormalities in albinism and best-corrected visual acuity (BCVA) is unclear. High-resolution spectral-domain optical coherence tomography (SD OCT) was used to quantify foveal retinal layer thicknesses and to assess the functional significance of foveal morphologic features in patients with albinism.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Forty-seven patients with albinism and 20 healthy control volunteers were recruited to the study.
  
  
  METHODS
  Using high-resolution SD OCT, 7×7×2-mm volumetric scans of the fovea were acquired (3-μm axial resolution). The B scan nearest the center of the fovea was identified using signs of foveal development. The thickness of each retinal layer at the fovea and foveal pit depth were quantified manually using ImageJ software and were compared with BCVA.
  
  
  METHODS
  Total retinal thickness, foveal pit depth, photoreceptor layer thickness, and processing layer thickness in relation to BCVA.
  
  
  RESULTS
  Total photoreceptor layer thickness at the fovea was correlated highly to BCVA (P = 0.0008; r = -0.501). Of the photoreceptor layers, the outer segment length was correlated most strongly to BCVA (P<0.0001; r = -0.641). In contrast, there was no significant correlation between either total retinal thickness or pit depth and BCVA (P>0.05). This was because of an inverse correlation between total photoreceptor layer thickness and total processing layer thickness (P<0.0001; r = -0.696).
  
  
  CONCLUSIONS
  Neither the total retinal thickness nor the pit depth are reliable indicators of visual deficit, because patients with similar overall retinal thickness had widely varying foveal morphologic features. In albinism, the size of the photoreceptor outer segment was found to be the strongest predictor of BCVA. These results suggest that detailed SD OCT images of photoreceptor anatomic features provide a useful tool in assessing the visual potential in patients with albinism.
  
  
  BACKGROUND
  The author(s) have no proprietary or commercial interest in any materials discussed in this article.
authors.affiliation: Ophthalmology Group, University of Leicester, Leicester, UK.
authors.forename: Sarim
authors.initials: S
authors.lastname: Mohammad
authors.forename: Irene
authors.initials: I
authors.lastname: Gottlob
authors.forename: Anil
authors.initials: A
authors.lastname: Kumar
authors.forename: Mervyn
authors.initials: M
authors.lastname: Thomas
authors.forename: Christopher
authors.initials: C
authors.lastname: Degg
authors.forename: Viral
authors.initials: V
authors.lastname: Sheth
authors.forename: Frank Antony
authors.initials: FA
authors.lastname: Proudlock
mesh_terms: D000293:Adolescent; D000328:Adult; D016117:Albinism, Ocular / Q000175:diagnosis / Q000503:physiopathology*; D016115:Albinism, Oculocutaneous / Q000175:diagnosis / Q000503:physiopathology*; D002648:Child; D005260:Female; D005584:Fovea Centralis / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012164:Retinal Diseases / Q000175:diagnosis / Q000503:physiopathology*; D055214:Retinal Photoreceptor Cell Outer Segment / Q000473:pathology; D041623:Tomography, Optical Coherence; D014792:Visual Acuity / Q000502:physiology