Contrast acuity in cataracts of different morphology and association to self-reported visual function.

PURPOSE: To evaluate the relationship between contrast acuity at declining contrast levels and the type and density of lens opacity in cataract. METHODS: Contrast acuity at declining contrast levels was determined with the Holladay Contrast Acuity Test, in relation to the type and density of age-related cataract in 180 patients with bilateral cataract and 20 control subjects with normal macular function. Cataracts were graded according to the Lens Opacities Classification System (LOCS) III of nuclear color (NC), nuclear opalescence (NO), cortical (C), and posterior subcapsular (P) cataract. Best-corrected visual acuity and near contrast acuity were determined in randomized order monocularly in both eyes. Visual difficulties in everyday life were evaluated, using the VF-14 questionnaire and the Cataract Symptom Score. RESULTS: The contrast-dependent effect of cataract on contrast acuity was statistically significant (P < 0.001; two-way ANOVA). In the comparison of early, intermediate, and advanced nuclear, nuclear-cortical, and posterior subcapsular cataracts (PSCs), significantly reduced contrast acuity scores were found for the PSC groups (P < 0.001). Comparison of nuclear and nuclear-cortical cataracts showed the contrast acuity scores to be comparable at all contrast levels (P > 0.05). High correlation coefficients were found between the LOCS III P score and the contrast acuity measurements (r = 0.77-0.84; P < 0.001). In contrast, the correlation coefficients of the NO, NC, and C scores were considerably lower (r = 0.45-0.66; P < 0.001). High correlation coefficients were also found between the contrast acuity measurements and self-reported functional vision. CONCLUSIONS: The statistically significant, contrast-dependent effect of cataract on contrast acuity supports the clinical relevance of recording visual acuity at low contrast levels in patients with age-related cataract. Particularly, the severity of PSC has a strong influence on the impairment of contrast acuity. Contrast acuity corresponded closely to the self-reported visual difficulties in everyday life.

Impairment of visual acuity and reading performance and the relationship with cataract type and density.

PURPOSE: To evaluate the association between the density of nuclear, cortical, and posterior subcapsular lens opacities and visual impairment in patients with cataract. METHODS: In 80 patients, visual acuity and reading performance were evaluated 1 day before and 4 weeks after cataract surgery. Cataracts were categorized and graded according to the Lens Opacities Classification System (LOCS) III of nuclear color (NC), nuclear opalescence (NO), cortical (C), and posterior subcapsular cataract (P). A multiple linear regression analysis and partial correlation coefficients were calculated. Data were also checked for significant pre- and postoperative differences in visual performance related to cataract grading. RESULTS: In the multiple linear regression analysis, significant associations were found between the improvement in visual acuity and reading performance after cataract surgery and the NC, NO, and P scores (P < 0.001); no significant association was found for the C score (P > 0.05). High partial correlation coefficients were found between the P score and the preoperative visual acuity (r = 0.6; P < 0.001), reading acuity (r = 0.74; P < 0.001), and maximum reading speed (MRS; r = -0.77; P < 0.001). Significant but lower partial correlation coefficients were found for the NO score. No significant partial correlation coefficients were found for the NC and C score. Significant pre- and postoperative differences in MRS were found in patients with P scores > or =3 or NO and NC scores > or =5, representing functionally relevant impairment. CONCLUSIONS: A strong association was found between visual impairment in patients with cataract and the severity of posterior subcapsular cataract (PSC) and nuclear opacity. Particularly in patients with PSC, deficits in reading performance significantly increased. The functionally relevant deficits in patients with P scores > or =3 or NO and NC scores > or =5, should be carefully considered for planning cataract surgery or visual rehabilitation.

Discriminative power of reading tests to differentiate visual impairment caused by cataract and age-related macular degeneration.

PURPOSE: To determine whether preoperative reading tests can be used for differentiating visual impairments with regard to the diagnosis of cataract and age-related macular degeneration (ARMD). SETTING: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. METHODS: Reading performance of patients with nuclear cataract, posterior subcapsular cataract, and ARMD were evaluated with respect to reading acuity, maximum reading speed, and critical print size; normal-sighted participants were tested as controls. A multivariate discriminant analysis of the 4 groups (100 eyes of 100 participants) was performed to evaluate how many patients could be correctly diagnosed by significant differences in the tested reading parameters. Subsequently, the nuclear cataract and posterior subcapsular cataract patients were compared with cataract patients with coexisting ARMD. RESULTS: Distance visual acuity was comparable in the nuclear cataract, posterior subcapsular cataract, and ARMD groups (P>.05). Reading acuity was significantly reduced in posterior subcapsular cataract and ARMD patients compared with nuclear cataract patients and controls (P<.0001). No significant difference in maximum reading speed was found between the nuclear cataract patients and the controls (P = .07), whereas the maximum reading speed of the posterior subcapsular cataract and ARMD patients was significantly reduced (P<.0001). In the discriminant analysis, it was possible to assign the correct diagnosis to 72% of the nuclear cataract patients, 76% of the posterior subcapsular cataract patients, 72% of the ARMD patients, and 92% of the controls. Comparing the reading performance of nuclear cataract and posterior subcapsular cataract patients and cataract patients with coexisting ARMD showed that reading performance was significantly impaired in the comorbid patients (nuclear cataract and ARMD, P<.001; posterior subcapsular cataract and ARMD, P<.05). CONCLUSION: The high discriminant accuracy shows that this standardized reading test system is a valuable diagnostic tool for evaluating functional visual impairments when distance visual acuity alone cannot elucidate the origin of functional impairment. Considering the significant discrepancies in reading performance among patients with nuclear cataract, posterior subcapsular cataract, and ARMD, reading tests may relevantly improve the clinical evaluation of patients with visual loss, even of patients with ocular comorbidity.

Functional vision with cataracts of different morphologies: comparative study.

PURPOSE: To evaluate the influence of cataract morphology on the functional vision of patients with age-related cataract and normal macular function and compare subjectively perceived functional impairments to distance visual acuity, reading acuity, and maximum reading speed between cataract types. SETTING: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. METHODS: Seventy-five patients awaiting first-eye cataract surgery were asked to characterize their visual difficulties in everyday life using a German version of the VF-14 questionnaire. Cataracts were categorized and graded using the Lens Opacities Classification System III. Monocular and binocular visual acuity and reading performance were determined in randomized order. RESULTS: There were significant differences in functional vision between nuclear cataracts and posterior subcapsular cataracts (PSC); the VF-14 score and the self-reported visual satisfaction were significantly lower in PSC patients (P<.05). Posterior subcapsular cataracts significantly increased self-reported impairment in distance and near vision, although the visual acuity was comparable to that in the other groups (P =.9). Significant differences in functional vision were also seen between PSC and nuclear-cortical cataracts (P<.05). No significant differences in functional vision were found between nuclear cataracts and nuclear-cortical cataracts (P>.05). CONCLUSIONS: The VF-14 questionnaire reliably evaluated functional differences caused by different cataract morphologies; these differences were underestimated when only visual acuity was measured. Patients with PSC had increased functional impairment, indicating that cataract surgical intervention is indicated at an earlier stage in these patients. The significant differences between the morphological types of cataract should be taken into consideration when the benefit of cataract surgery is to be measured on the basis of functional improvement.

Reading performance depending on the type of cataract and its predictability on the visual outcome.

PURPOSE: To investigate the influence of various types of cataract on reading performance in a standardized reading test setting. SETTING: Department of Ophthalmology, University of Vienna, Vienna, Austria. METHODS: The reading performance of 94 eyes with age-related cataract and normal macular function was evaluated with the Radner Reading Charts preoperatively and 4 weeks after cataract surgery. Distance visual acuity was tested with the ETDRS charts. Cataracts were graded using the Lens Opacities Classification System (LOCS) III, on which NO is nuclear opalescence and NC is nuclear color. RESULTS: Patients with pure nuclear cataracts (LOCS III: NO/NC 2.1-5) achieved a normally high MRS (99.84% +/- 7.65% of their postoperative MRS): preoperative MRS(1): 190.6 +/- 30.74 words per minute (wpm); postoperative MRS(2): 191.21 +/- 29.36 wpm. Patients with mixed nuclear-cortical cataracts (LOCS III: NO/NC 2.1-5; C>2) preoperatively achieved 96.96% +/- 5.6% of their postoperative MRS (MRS(1): 175.77 +/- 31.54 wpm; MRS(2): 181.34 +/- 30.56 wpm). In dense nuclear cataracts (LOCS III: NO/NC>5), the MRS was significantly reduced, achieving only 72.64 +/- 19.19% of the postoperative MRS (MRS(1): 133.06 +/- 39.43 wpm; MRS(2): 185.76 +/- 40.18 wpm). In posterior subcapsular cataracts, the preoperative MRS (134.1 +/- 33.72 wpm) was significantly lower than postoperatively (191.14 +/- 27.08 wpm). CONCLUSIONS: In contrast to dense nuclear cataracts and posterior subcapsular cataracts, the preoperative reading speed of patients with pure nuclear or nuclear-cortical cataracts was normal at large print sizes. The preoperative evaluation of reading acuity and speed with standardized reading tests can therefore be used to estimate the postoperative reading performance in the latter 2 types of cataract.

Reading performance with a refractive multifocal and a diffractive bifocal intraocular lens.

PURPOSE: To evaluate the reading performance of a diffractive bifocal (811E, Pharmacia) and a refractive multifocal (SA40N, Allergan) intraocular lens (IOL) and compare it with that of a monofocal IOL (811C, Pharmacia) with respect to reading acuity, reading speed based on print size, maximum reading speed, reading distance, and critical print size. SETTING: Department of Ophthalmology, University of Vienna, Vienna, Austria. METHODS: This study comprised 120 pseudophakic eyes of 70 patients; each IOL group had 40 eyes. The patients' age, sex, and best corrected logMAR visual acuity were recorded. Reading acuity and speed were tested monocularly. Reading acuity was determined in logRAD (ie, the reading equivalent of logMAR). Patients with bifocal and multifocal IOLs read with best distance correction and patients with a monofocal IOL, with an addition of +3.0 diopters. RESULTS: The age, mean spherical equivalent, cylinder, and best corrected distance visual acuity were comparable among the 3 groups. The mean logRAD reading acuity was 0.17 +/- 0.18 (SD) in the 811E group (94.0% of logMAR), 0.31 +/- 0.13 in the SA40N group (73.2% of logMAR), and 0.24 +/- 0.22 in the 811C group (94.1% of logMAR). The reading acuity in the SA40N group was statistically significantly lower than in the 811E and 811C groups. The best reading distance was 30 cm in the 811E group and 40 cm in the SA40N group. The mean maximum reading speeds in words per minute were comparable: 187.5 +/- 26.1 (811E), 171.0 +/- 21.1 (SA40N), and 179.4 +/- 21.6 (811C). The reading speed, which ranged from logRAD 0.7 to 0.3, and the critical print size in the SA40N group were significantly worse than in the 811E and 811C groups. The mean critical print size in the 811E group was significantly worse than in the 811C group. CONCLUSIONS: Reading performance was acceptable in the bifocal and multifocal IOL patients, with the diffractive bifocal IOL performing best in a standardized reading test setting.

Comparison of visual acuities at different distances and defocus curves.

PURPOSE: To evaluate how visual acuities at different distances correlate with results from defocus curves. SETTING: Department of Ophthalmology and Institute of Medical Physics, University of Vienna, Medical School, Vienna, and Department of Ophthalmology, Krankenhaus St. Pölten, St. Pölten, Austria. METHODS: This study comprised 15 eyes of 14 patients with a mean age of 67.9 years +/- 9.7 (SD) with a monofocal silicone intraocular lens (911A, Pharmacia). The best corrected distance visual acuity was determined at viewing distances of 6 m, 2 m, 1 m, 67 cm, 50 cm, 40 cm, and 33 cm using logMAR charts. Defocus curves were then evaluated from -3.0 to -0.5 diopter (D) at 0.5 D increments from the best distance correction at a viewing distance of 6 m. RESULTS: The mean distance visual acuity was logMAR 0.08 +/- 0.07. The visual acuity graph from the testing at different distances was above the defocus graph at all testing points. Comparison of the visual acuity results from the 2 tests revealed statistically significant differences in the range from 2 m (-0.5 D) to 33 cm (-3.0 D). CONCLUSIONS: Results of defocus curves disregard the diminutions of minus glasses, the normally restricted viewing distance to 6 m for distance acuity determination, and in particular the physiological miosis caused by the near-point reaction.