title: Correlation of outer nuclear layer thickness with cone density values in patients with retinitis pigmentosa and healthy subjects.
abstract: OBJECTIVE
  We studied the correlation between outer nuclear layer (ONL) thickness and cone density in normal eyes and eyes with retinitis pigmentosa (RP).
  
  
  METHODS
  Spectral-domain optical coherence tomography (SD-OCT) scans were acquired using a displaced pupil entry position of the scanning beam to distinguish Henle's fiber layer from the ONL in 20 normal eyes (10 subjects) and 12 eyes with RP (7 patients). Cone photoreceptors were imaged using adaptive optics scanning laser ophthalmoscopy. The ONL thickness and cone density were measured at 0.5° intervals along the horizontal meridian through the fovea nasally and temporally. The ONL thickness and cone density were correlated using Spearman's rank correlation coefficient r.
  
  
  RESULTS
  Cone densities averaged over the central 6° were lower in eyes with RP than normal, but showed high variability in both groups. The ONL thickness and cone density were significantly correlated when all retinal eccentricities were combined (r = 0.74); the correlation for regions within 0.5° to 1.5° eccentricity was stronger (r = 0.67) than between 1.5° and 3.0° eccentricity (r = 0.23). Although cone densities were lower between 0.5° and 1.5° in eyes with RP, ONL thickness measures at identical retinal locations were similar in the two groups (P = 0.31), and interindividual variation was high for ONL and cone density measures. Although ONL thickness and retinal eccentricity were important predictors of cone density, eccentricity was over 3 times more important.
  
  
  CONCLUSIONS
  The ONL thickness and cone density were correlated in normal eyes and eyes with RP, but both were strongly correlated with retinal eccentricity, precluding estimation of cone density from ONL thickness. (ClinicalTrials.gov number, NCT00254605.).
authors.affiliation: Department of Ophthalmology, University of California, San Francisco, San Francisco, California, United States.
authors.forename: Moreno
authors.initials: M
authors.lastname: Menghini
authors.affiliation: School of Optometry and Vision Science Graduate Group, University of California, Berkeley, Berkeley, California, United States West Coast Retina Medical Group, San Francisco, California, United States.
authors.forename: Brandon J
authors.initials: BJ
authors.lastname: Lujan
authors.affiliation: Department of Ophthalmology, University of California, San Francisco, San Francisco, California, United States.
authors.forename: Shiri
authors.initials: S
authors.lastname: Zayit-Soudry
authors.affiliation: Department of Ophthalmology, University of California, San Francisco, San Francisco, California, United States.
authors.forename: Reema
authors.initials: R
authors.lastname: Syed
authors.affiliation: Department of Ophthalmology, University of California, San Francisco, San Francisco, California, United States Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California, United States F.I. Proctor Foundation for Research in Ophthalmology, University of California, San Francisco, San Francisco, California, United States.
authors.forename: Travis C
authors.initials: TC
authors.lastname: Porco
authors.affiliation: School of Optometry and Vision Science Graduate Group, University of California, Berkeley, Berkeley, California, United States.
authors.forename: Kristine
authors.initials: K
authors.lastname: Bayabo
authors.affiliation: Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States.
authors.forename: Joseph
authors.initials: J
authors.lastname: Carroll
authors.affiliation: School of Optometry and Vision Science Graduate Group, University of California, Berkeley, Berkeley, California, United States.
authors.forename: Austin
authors.initials: A
authors.lastname: Roorda
authors.affiliation: Department of Ophthalmology, University of California, San Francisco, San Francisco, California, United States.
authors.forename: Jacque L
authors.initials: JL
authors.lastname: Duncan
mesh_terms: D000328:Adult; D002452:Cell Count; D004596:Electroretinography; D005260:Female; D005500:Follow-Up Studies; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D009887:Ophthalmoscopy; D011446:Prospective Studies; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology*; D055214:Retinal Photoreceptor Cell Outer Segment / Q000473:pathology*; D012174:Retinitis Pigmentosa / Q000473:pathology* / Q000503:physiopathology; D041623:Tomography, Optical Coherence; D014792:Visual Acuity; D055815:Young Adult
keywords: adaptive optics scanning laser ophthalmoscopy; cone density; optical coherence tomography; outer nuclear layer thickness; retinitis pigmentosa