title: The Effect of Cataract on Early Stage Glaucoma Detection Using Spatial and Temporal Contrast Sensitivity Tests.
abstract: BACKGROUND
  To investigate the effect of cataract on the ability of spatial and temporal contrast sensitivity tests used to detect early glaucoma.
  
  
  METHODS
  Twenty-seven glaucoma subjects with early cataract (mean age 60 ± 10.2 years) which constituted the test group were recruited together with twenty-seven controls (cataract only) matched for age and cataract type from a primary eye care setting. Contrast sensitivity to flickering gratings at 20 Hz and stationary gratings with and without glare, were measured for 0.5, 1.5 and 3 cycles per degree (cpd) in central vision. Perimetry and structural measurements with the Heidelberg Retinal Tomograph (HRT) were also performed.
  
  
  RESULTS
  After considering the effect of cataract, contrast sensitivity to stationary gratings was reduced in the test group compared with controls with a statistically significant mean difference of 0.2 log units independent of spatial frequency. The flicker test showed a significant difference between test and control group at 1.5 and 3 cpd (p = 0.019 and p = 0.011 respectively). The percentage of glaucoma patients who could not see the temporal modulation was much higher compared with their cataract only counterparts. A significant correlation was found between the reduction of contrast sensitivity caused by glare and the Glaucoma Probability Score (GPS) as measured with the HRT (p<0.005).
  
  
  CONCLUSIONS
  These findings indicate that both spatial and temporal contrast sensitivity tests are suitable for distinguishing between vision loss as a consequence of glaucoma and vision loss caused by cataract only. The correlation between glare factor and GPS suggests that there may be an increase in intraocular stray light in glaucoma.
authors.affiliation: School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, BT521SA, United Kingdom.
authors.forename: Johann
authors.initials: J
authors.lastname: Klein
authors.affiliation: Faculty of Science, Engineering and Computing, Kingston University, Penrhyn Road,Kingston-upon-Thames, KT1 2EE, United Kingdom.
authors.forename: Barbara K
authors.initials: BK
authors.lastname: Pierscionek
authors.affiliation: Faculty of Science, Engineering and Computing, Kingston University, Penrhyn Road,Kingston-upon-Thames, KT1 2EE, United Kingdom.
authors.forename: Jan
authors.initials: J
authors.lastname: Lauritzen
authors.affiliation: Ordination Dr. Karin Derntl, Ophthalmologist, Wartenburgerstr. 1b, 4840 Vöcklabruck, Austria.
authors.forename: Karin
authors.initials: K
authors.lastname: Derntl
authors.affiliation: Department of Ophthalmology, Poznań City Hospital, Poznań, Poland; Department of Ophthalmology, University of Warmia and Mazury, Olsztyn, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Grzybowski
authors.affiliation: School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, BT521SA, United Kingdom.
authors.forename: Margarita B
authors.initials: MB
authors.lastname: Zlatkova
mesh_terms: D000328:Adult; D000368:Aged; D002386:Cataract / Q000503:physiopathology*; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D005403:Fixation, Ocular; D019466:Glare; D005901:Glaucoma / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D013997:Time Factors; D058609:Visual Field Tests / Q000379:methods*