title: Quantification of dark adaptation dynamics in retinitis pigmentosa using non-linear regression analysis.
abstract: OBJECTIVE
  Non-linear regression analysis was used to determine dark adaptation indices in people with retinitis pigmentosa and in control subjects.
  
  
  METHODS
  Dark adaptation data were collected for 13 people with retinitis pigmentosa and 21 controls using the Goldmann-Weekers Dark Adaptometer. Data were analysed using an exponential non-linear regression model and dark adaptation indices derived. The results were compared to age-related values.
  
  
  RESULTS
  The mean cone threshold of the group with RP (4.73 +/- 0.19 log units) was significantly greater than that found in the control group (3.69 +/- 0.12 log units). The rate of cone dark adaptation in the RP group was not significantly different from that of the control group. The a break in the RP group (6.46 +/- 0.70 minutes) was delayed when compared to the control group (4.29 +/- 0.21 minutes) and the rate of rod dark adaptation in the RP group was slower (10 +/- 2 per cent per minute) than that of the control group (15 +/- 1 per cent per minute).
  
  
  CONCLUSIONS
  This study has shown that a relatively simple data analysis can provide a more quantitative and intuitive description of dark adaptation rates in people with retinal disease. This technique will enable more effective use of dark adaptometry as a supplement to objective electrophysiology, when monitoring people with retinitis pigmentosa.
authors.affiliation: Department of Optometry, Faculty of Health Sciences, National University of Malaysia, Kuala Lumpur, Malaysia.
authors.forename: Rokiah
authors.initials: R
authors.lastname: Omar
authors.forename: Peter
authors.initials: P
authors.lastname: Herse
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003623:Dark Adaptation; D004056:Differential Threshold; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics; D012044:Regression Analysis; D017949:Retinal Cone Photoreceptor Cells / Q000503:physiopathology; D017948:Retinal Rod Photoreceptor Cells / Q000503:physiopathology; D012174:Retinitis Pigmentosa / Q000503:physiopathology*