OBJECTIVE

To investigate influence of cataract morphology on quality of vision in measurement of straylight and contrast sensitivity (CS), and to determine which type of cataract presents higher impairment of quality of vision.

METHODS

In a cross-sectional study, 76 eyes of 76 age-related cataract patients who treated in the Eye Hospital of China Medical University from February 2010 to December 2010 with a best corrected visual acuity (BCVA) of 0.5 or better, were classified into 3 groups: cortical cataract group (33 eyes of 33 subjects), nuclear cataract group (20 eyes of 20 subjects), posterior cataract group (23 eyes of 23 subjects), as well as normal control group (26 eyes of 26 subjects). BCVA, CS and intraocular straylight were respectively measured with phoropter, C-Quant straylight meter and CSV-1000E contrast sensitivity tester. Subjective quality of vision was examined with visual function index-14 (VF-14).

RESULTS

Age, BCVA, straylight levels and CS at 3, 6, 12 and 18 c/d were 66.1 ± 6.7, 0.58 ± 0.10, 1.50 ± 0.24, 1.33 ± 0.19, 1.21 ± 0.18, 1.01 ± 0.19, and 0.50 ± 0.09 in the cortical group, 67.6 ± 5.0, 0.62 ± 0.11, 1.46 ± 0.11, 1.38 ± 0.19, 1.28 ± 0.19, 1.09 ± 0.18, and 0.54 ± 0.09 in the nuclear group, 60.6 ± 7.1, 0.57 ± 0.09, 1.85 ± 0.26, 1.11 ± 0.12, 1.04 ± 0.13, 0.89 ± 0.13, 0.34 ± 0.11 in the posterior group, and 63.9 ± 7.3, 1.00 ± 0.11, 1.28 ± 0.17, 1.58 ± 0.19, 1.72 ± 0.21, 1.53 ± 0.19, and 0.71 ± 0.11 in the normal eyes, respectively (F = 9.983, F = 103.925, F = 31.760, F = 28.871, F = 65.889, F = 66.453, F = 61.540; P = 0.000). In SNK-q test, BCVA, levels of straylight and CS at each spatial frequency in the normal eyes were significantly different from that in cataracts of different morphologies (P < 0.05); BCVA did not differ significantly for cataract of the 3 types (P > 0.05); age, straylight levels and CS at each spatial frequency in posterior cataract had significant differences compared with that in cortical and nuclear cataracts (P < 0.05); no significant differences were found between the cortical and nuclear cataracts (P > 0.05). The mean visual function index-14 (VF-14) showed significantly differences (F = 10.211, P = 0.000). When controlling for ages, there were no significant correlation between BCVA and straylight in cortical, nuclear and posterior cataracts (r = -0.227, r = -0.279, r = -0.373; P > 0.05). Correlations between BCVA and CS at 3, 6, 12 and 18 c/d were: r = 0.569, r = 0.517, r = 0.500, r = 0.449 (P < 0.01) in cortical cataracts; r = 0.657, r = 0.542, r = 0.513, r = 0.492 (P < 0.05) in nuclear cataracts; however, BCVA had no significant correlation with CS at spatial frequency any in posterior cataracts (P > 0.05). VF-14 significantly correlated with BCVA, straylight and CS in cortical and nuclear cataracts (r = 0.670, r = -0.740, r = 0.811, r = 0.826, r = 0.809, r = 0.720, P < 0.01; r = 0.731, r = -0.721, r = 0.816, r = 0.769, r = 0.738, r = 0.728, P ≤ 0.01); VF-14 correlated with straylight and CS (r = -0.910, r = 0.879, r = 0.896, r = 0.874, r = 0.844; P < 0.001), whereas VF-14 did not correlate with BCVA in posterior cataracts (r = 0.370, P = 0.090).

CONCLUSIONS

Since visual acuity could underestimate the influence of cataract morphology on quality of vision, most notably in posterior cataract, straylight and CS are sensitive, complementary to BCVA when estimating real-world quality of vision of cataracts, and should be taken into account when considering therapy and cataract surgery.