Abstract
Purpose: :
To investigate changes in colour vision after cataract surgery and to compare three types of colour vision assessment.
Methods: :
Patients with cataract and no other coexisting ocular pathology were recruited. Colour vision was assessed using the Cambridge Colour Contrast trivector (CCCT), Ishihara Pseudoisochromatic Plates (IPP) ,and Farnsworth Munsell 100 hue (FM) test which were all conducted in a randomised order. Other data collected included refractive error, LogMAR visual acuity using the EDTRS chart ,and contrast sensitivity using the Pelli–Robson chart. All patients has dilated ocular examination and grading of lens opacity pre–operatively with LOCS III score chart.
Results: :
Five patients have completed their follow–up to date. Mean age 76 years ( SD 8.7). Pre–operative mean refractive error was 1.225D ( range –2.125D to 4.25D ) .and post operatively 0.62D ( range 0.15 D to 1.375D). Visual acuity improved from mean 0.416 (SD 0.31) LogMAR to 0.16 (SD 0.11). The mean contrast sensitivity improved from 0.94 (SD 0.51) at baseline to 1.38 (SD 0.16). Four patients identified all the IPPs correctly at baseline and post operatively One patient identified all IPPs correctly at baseline and two incorrect plates post operatively. The mean of the square root of the total error scores with the FM caps test at baseline was 16.11 (SD 3.27) and 11.99 (SD 2.19 ) post operatively (p=0.0474). The mean of the partial error square root errors in the blue yellow region was 9.63 (SD 1.80 ) at baseline compared to 6.54 (SD 0.56 ) post operatively (p=0.0066). The mean protan, deutan and tritan thresholds at baseline were 769 (SD 338.89) ,439.6 (SD 429.84) and 971.2 (SD 194.21). Post operatively the mean protan, deutan and tritan thresholds were. 336.6 (SD 428.62), 146.2 (SD 34.01) and 558.4 (SD 259.65). Statistical analysis showed a significant difference between baseline and post operatively threshold in the tritan axis only (p=0.0216).
Conclusions: :
Colour vision defects are present in cataract patients predominantly in the tritan axis. Identification of the defect seems more reliable with Farnworth Munsell 100 hue and Cambridge Colour Contrast test compared to Ishihara pseudoisochromatic plates.
Keywords: color vision • cataract