title: Correlation of inner retinal thickness evaluated by spectral-domain optical coherence tomography and contrast sensitivity in Parkinson disease.
abstract: BACKGROUND
  To compare inner retinal layer (IRL) thickness measured by spectral-domain optical coherence tomography (SD-OCT) and contrast sensitivity (CS) in patients with Parkinson disease (PD) and in healthy control (HC) subjects.
  
  
  METHODS
  Consecutive patients with and without PD were prospectively analyzed using SD-OCT and Pelli-Robson CS testing. SD-OCT IRL (ganglion-cell complex) thickness, consisting of the nerve fiber layer, ganglion cell layer, and inner plexiform layer, was segmented using an RTVue Model-RT100 with an EMM5 scan parameter covering a 5.0 × 5.0 mm cube centered on the fovea. Thickness voxel measurements at 0.25-mm intervals at sequential radial distances from the foveola were acquired horizontally and vertically. SD-OCT thickness raw data files were imported and analyzed within MATLAB (version 7.10.0). A database of CS scores and IRL thickness values by foveal location was constructed and statistically evaluated using JMP 10 (SAS Institute, Inc, Cary, NC).
  
  
  RESULTS
  The results were compared between 28 eyes of 14 patients with PD and 28 eyes of 14 HC subjects. Controlling for age, mean CS scores of monocular right and randomized eyes were statistically lower in PD eyes (P < 0.05). IRL was significantly thinner in PD eyes than in HC eyes at several distances from the foveola (P < 0.05). The most numerous and significant thickness differences by diagnosis were located in the superior quadrant at a distance of 1.00-1.75 mm from the foveal center (17 μm; P < 0.01, maximum significant thickness difference and P value). Correlation was demonstrated between monocular CS and IRL thickness by diagnosis at multiple foveal locations for HC eyes as follows: nasal quadrant, 0.75-1.00 mm (P < 0.02); temporal quadrant, 0.50-1.00 mm (P < 0.05); superior quadrant, 1.00 mm (P < 0.05); and inferior quadrant, 1.00 mm (P < 0.03). No significant correlation was found between monocular CS and IRL thickness within PD subjects (P > 0.05 for each foveal location measured).
  
  
  CONCLUSIONS
  CS and foveal IRL thickness are decreased in patients with PD. CS and IRL thickness correlated in HC subjects; however, no such correlation was demonstrated in PD. The functional deficit of dopaminergic interneurons, including amacrine cells, may outstrip the anatomic structural changes in the inner retina of PD patients. Inner retinal atrophic changes may underlie the pathogenesis of CS deficit and IRL thinning in PD.
authors.affiliation: College of Medicine, SUNY-Downstate Medical Center, Brooklyn, New York 11203, USA. christopher.adam@downstate.edu
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Adam
authors.forename: Eric
authors.initials: E
authors.lastname: Shrier
authors.forename: Yin
authors.initials: Y
authors.lastname: Ding
authors.forename: Sofya
authors.initials: S
authors.lastname: Glazman
authors.forename: Ivan
authors.initials: I
authors.lastname: Bodis-Wollner
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications* / Q000175:diagnosis*; D010468:Perceptual Disorders / Q000175:diagnosis / Q000209:etiology*; D012160:Retina / Q000473:pathology*; D041623:Tomography, Optical Coherence