Visual functional outcomes of cataract surgery in the United States, Canada, Denmark, and Spain

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1 Visual functional outcomes of cataract surgery in the United States, Canada, Denmark, and Spain Report of the International Cataract Surgery Outcomes Study Jens Christian Norregaard, MD, PhD, Peter Bernth-Petersen, MD, PhD, Jordi Alonso, MD, PhD, Tavs Folmer Andersen, MSc, PhD, Gerard F. Anderson, PhD Purpose: To compare functional outcomes after cataract surgery performed at 4 sites in 4 countries that have been described as having significant differences in the organization of care and patterns of clinical practice. Setting: Multicenter cohort study from the United States, Canada, Denmark, and Spain. Methods: Clinical data and patient interview data were collected preoperatively and 4 months postoperatively. Functional outcomes were assessed by the Visual Function Index (VF-14), a self-reported measure of visual function. Scores on the VF-14 range from 0 (maximum impairment) to 100 (no impairment). Results: Unilateral surgery was performed in 1073 patients. In this subgroup, the odds of achieving an optimal functional outcome (VF-14 score 95) were similar among sites after controlling for differences in case mix. Bilateral surgery was performed in 211 patients. A postoperative visual acuity of 0.50 or better in both eyes was reported in 155 patients. However, 37% of these patients reported visual function impairment (VF-14 score 95). Conclusions: A previously identified variation in treatment modalities among the 4 sites did not have a significant effect on the odds of achieving an optimal functional outcome. In addition to visual acuity measurements, the VF-14 index provides information on functional outcomes that is useful, especially in studies assessing the benefits of cataract surgery in a public health care setting. J Cataract Refract Surg 2003; 29: ASCRS and ESCRS A World Health Organization (WHO) publication classifying the disability of people across the world released in challenges mainstream ideas on how health and disability information is reported. The International Classification of Functioning, Disability and Health (ICF) is the result of a 7-year effort involving active participation of more than 65 countries. Unlike Accepted for publication March 24, Reprint requests to Jens Christian Norregaard, MD, PhD, University Eye Clinic, Frederiksberg Hospital, Nordre Fasanvej 57, DK 2000 Fredriksberg C, Denmark. jens.c.norregaard@fh.hosp.dk. the well-know ICD-10 system, the ICF documents the impact of a disability on physical and social well-being. The ICD-10 is a system for coding diagnoses, while the ICF is for coding the consequences of a disease. The 2 systems are complementary. Together, information on diagnosis and function provides a better picture of the health of people or populations. Based on this idea, WHO strongly recommends that the medical profession introduce measures of function as a supplement to traditional health indicators (WHO resolution, 54th World Health Assembly 2001, WHA54.21, agenda item 13.9). In ophthalmology, visual acuity is the main health indicator. 2 Several new measures for evaluating visual func ASCRS and ESCRS /03/$ see front matter Published by Elsevier Inc. doi: /s (03)

2 tion have been introduced. 3 5 One of these, the Visual Function Index (VF-14), is a self-report instrument. Both WHO (in its 2001 resolution) and the American Academy of Ophthalmology (AAO) 2 recommend the use of functional indexes. The decision to perform cataract surgery should not be made exclusively on the basis of a visual acuity measurement; rather, subjective and objective criteria should be fulfilled. This basic concept has been stated, for example, in the United States in clinical practice guidelines 4 and in AAO s Preferred Practice Patterns. 2,6 The objective criterion is met when a cataract is observed and visual acuity is affected. The subjective criterion is met when the ability to perform needed or desired activities of daily living is impaired by the cataract. Although it seems obvious that both visual acuity and visual function should be exam- ined when evaluating indications for cataract surgery, it is unclear whether self-report instruments are useful in evaluating outcomes of cataract surgery. The International Cataract Surgery Outcomes Study was established to assess the impact of variation in the management of cataract on patient outcomes among 4 very different health care systems: the United States, Denmark, the Province of Manitoba (Canada), and the City of Barcelona (Spain). In this prospective study, patients were assessed preoperatively and 4 months postoperatively. At the 4 sites, instruments originally developed by the United States National Cataract Patient Outcomes Research Team (PORT) were used for the primary data collection of interview and clinical data. Previous papers describe the differences in the organization of care, preoperative testing, and predomi- nant surgical and anesthesia techniques among the 4 sites. 7,8 Similar visual acuity outcomes were obtained among the 4 sites after controlling for differences in case mix 9 despite differences in surgical technique and the rates of complications. 10 In the present study, the VF-14 index was used to compare visual functional outcomes in 1284 patients at the 4 sites. In a subgroup of 211 patients having cataract surgery in both eyes, visual acuity and VF-14 outcomes were compared. We also evaluated whether a self-report instrument such as the VF-14 adds infor- mation that is not obtained by a simple measurement of visual acuity. Patients and Methods Participants Patients were eligible for inclusion in the study if they were scheduled for cataract surgery and were 50 years or older. Patients were excluded if they had previous cataract surgery or if the planned cataract surgery was combined with a glaucoma, corneal, or vitreoretinal procedure. Further exclusions were made if patients were not living within speci- fied recruitment areas, did not speak the primary language of the area, were deaf or confused, or did not have access to a telephone. Patients were recruited from contributing ophthalmologists as follows: United States (75 ophthalmol- ogy practices), Manitoba (12 ophthalmology practices), Den- mark (all 17 ophthalmology departments at public hospitals in Denmark), and Barcelona (4 public-sector and 6 private- sector ophthalmology practices). Patients were enrolled consecutively in the study from all practices. The recruitment of patients has been described in detail. 3,9 The local ethics committees on human research at each site approved the studies. Outcome Measures At baseline, a full preoperative medical history and ophthalmic examination including best corrected visual acuity and slitlamp and fundus evaluations were obtained for each patient. Clinical data were obtained from ophthalmologists on structured data sheets that had checklists for responses. The ophthalmologists also reported intraoperative techniques and 4-month postoperative clinical outcomes on a structured data sheet. Each patient was interviewed by telephone at the time of enlistment for surgery and 4 months postoperatively. Visual functional status was assessed by the VF This index scores functional limitations in daily living as perceived by the patient. It is based on 14 vision-dependent activities performed in everyday life that can be affected by cataract. Patients are asked how much difficulty they have doing each activity, even with glasses. A score is obtained by averaging responses across all activities. The final scores range from 0 (worst level of function) to 100 (best level of function). An item is not included in the scoring if the patient does not do the activity for reasons other than his or her vision (ie, not applicable). General health status was assessed by the Sickness Impact Profile (SIP), a valid, reliable measure of general health status. 11 The SIP scores range from 0 (absence of general dys- function) to 100 (maximum level of general dysfunction). Statistical Analysis Differences in demographic and clinical characteristics among sites were tested statistically using chi-square tests for categorical variables and analysis of variance tests for continuous variables. The mean visual acuity was calculated as the geometric mean. 12 All visual acuity measurements are 2136 J CATARACT REFRACT SURG VOL 29, NOVEMBER 2003

3 presented as Snellen decimal fractions. The occurrence of (P.001). A subanalysis of data showed that this was perioperative complications is presented as a dichotomous largely because of a greater proportion of patients with variable (complication versus no complication) as described diabetic retinopathy in Barcelona (data not presented). in detail elsewhere. 11 Multiple logistic regression was used to compare visual A detailed presentation of differences in rates of various function outcomes of surgery at the 4 sites and to identify perioperative complications among sites has been preoperative and perioperative factors associated with a poor published. 11 visual function outcome. Patients having unilateral surgery The uncontrolled mean of the 4-month postoperawere included in the analysis as the number having surgery tive VF-14 scores varied significantly among sites as in both eyes did not allow meaningful analysis. follows: 93 in the United States, 90 in Manitoba, 92 Odds ratios for achieving an optimal postoperative outin Denmark, and 85 in Barcelona (P.001) (Table 2). come were estimated. Optimal outcome was defined as a VF-14 score of 95 or higher. The results from Manitoba, However, in a regression model, 3 variables comparing Denmark, and Barcelona were compared with those in the postoperative visual function in Manitoba, Denmark, United States. To adjust for differences in case mix among and Barcelona to that in the United States were not sites, several patient characteristics were included in the analy- significant (Table 3). This indicates that the odds of sis. Age and preoperative visual acuity were categorized in having an optimal postoperative visual function (VFgroups to examine the significance of subgroups comprising 14 score 95) were similar among sites after controlling a small number of patients (eg, very old patients). The preopfor differences in case mix. The case-mix variables were erative SIP score was included as an indicator of general health. Age-related macular degeneration (ARMD) was the age, sex, general health status, ocular comorbidity, pre- predominant ocular comorbidity in the samples and was operative visual status, and preoperative VF-14 scores. included as absent, present, or not assessable because of ma- Similar outcomes at the 4 sites were observed despite ture cataract. Age-related macular degeneration was defined significant differences in the rate of complications and as geographic atrophy, neovascular change, disciform scar, the surgical techniques used (Table 1). Similar results macular edema, or macular hole. The presence of ocular were obtained when optimal functional outcome was comorbidities in the operative eye was represented by a single dichotomous variable (comorbidity versus no comorbidity) defined as a VF-14 score of 100 (data not shown) and as the sample size did not allow meaningful analysis of single when linear regression was performed (data not shown). diagnoses of ocular comorbidity. Some patient characteristics were statistically signif- icant predictors of a suboptimal outcome (VF-14 score 95) (Table 3). The risk of having a suboptimal postop- Results erative visual function increased with age, female sex, In the United States, 888 eligible patients met the and lower preoperative VF-14 score. The risk of a subinitial enrollment criteria and 772 patients agreed to optimal outcome was higher in patients with ARMD participate (response rate 87%). In Canada, 159 of or other ocular comorbidity than in those with no ocular 226 eligible patients agreed to participate (response rate comorbidity. Preoperative general health status (SIP 70%) and in Barcelona, 200 of 219 eligible patients score) was not a significant predictor of a suboptimal (response rate 91%). Of 311 eligible and enrolled Dan- visual function outcome. Low preoperative visual acuity ish patients, 291 (94%) eventually participated. was of marginal importance (P.06). Of the total cross-national sample of 1422 patients, To examine whether the VF-14 index adds to the preoperative interview data and preoperative and intra- evaluation of outcomes, patients who had had surgery operative clinical data were available for 1349 patients in both eyes by the 4-month examination (n 211, (95%). Four-month postoperative interview data were missing data for 2) (Table 4) were evaluated. An optimal obtained for 1284 patients (90%). At 4 months, 211 visual acuity outcome (Snellen 0.50 or better) was patients had surgery in both eyes, leaving 1073 patients achieved in both eyes in 155 patients and 1 eye in 30 with unilateral surgery for regression analyses. patients. In 24 patients, the postoperative visual acuity Demographic and clinical characteristics of the pa- was worse than 0.50 in both eyes. In the 3 groups, tients varied significantly among the 4 sites (Table 1). 37%, 50%, and 54%, respectively, still had some visual Substantially more ocular comorbidity was observed in function impairment (VF-14 score 95). When an Barcelona (32%) than at the other sites (13% to 25%) optimal visual acuity outcome was defined as a Snellen J CATARACT REFRACT SURG VOL 29, NOVEMBER

4 Table 1. Distribution of demographic and clinical characteristics of the operative eye of 1073 patients having unilateral cataract surgery in the United States, Manitoba, Denmark, and Barcelona. Study Site U.S. Manitoba Denmark Barcelona Total (n 570) (n 111) (n 256) (n 136) (n 1073) P Value* Preoperative Female sex (%) Age, y (%) 50 to to to Mean Median SIP score Macula (%).001 Normal ARMD Not assessable Ocular comorbidity, other (%).001 Absent Present Visual Acuity (%) to to to Mean Intraoperative Surgical technique (%).001 Extracapsular Phacoemulsification Perioperative complications (%) Absent Present Postoperative Visual acuity (%) to to to Mean ARMD age-related macular degneration *Difference among sites Chi-square test Analysis of variance, F test 2138 J CATARACT REFRACT SURG VOL 29, NOVEMBER 2003

5 Table 2. Preoperative and postoperative VF-14 scores in patients having unilateral cataract surgery. Study Site U.S. Manitoba Denmark Barcelona Total Score* (n 570) (n 111) (n 256) (n 136) (n 1073) P Value Preoperative Mean Patients with score 95 (%) 62 (11) 2 (2) 20 (8) 15 (11) 99 (9).05 Patients with score 100 (%) 22 (4) 1 (1) 7 (3) 8 (6) 38 (4).05 Postoperative Mean Patients with score 95 (%) 318 (56) 53 (48) 157 (61) 74 (54) 602 (56).05 Patients with score 100 (%) 203 (36) 29 (26) 105 (41) 45 (33) 382 (36).05 *A VF-14 score of 100 indicates no visual functional impairment; a score of 0 indicates maximum visual functional impairment. Differences among sites; analysis of variance, F test Difference across sites; chi-square test acuity of 0.67 or better, the results were similar (35%, tion, 54th World Health Assembly 2001, WHA54.21, 55%, and 49%, respectively). agenda item 13.9) and AAO. 2 The validity of the VF-14 instrument has been reported as acceptable in many settings and by various Discussion techniques including examination of internal consis- To evaluate the effect of alternative treatment mo- tency, 3 correlation with other variables of vision, 3,13,14 dalities on health outcomes, the U.S. Agency for Health test retest reliability, 15 and responsiveness to change. 14 Care and policy initiated the PORT study of variations Similar results outside the United States have been rein preoperative, intraoperative, and postoperative cata- ported. 13 In addition to assessing cataract surgery outract surgical management. 3 This study was extended to comes, the VF-14 has been found useful in the study of investigate similar issues at 4 international sites: United corneal disease, 16 refractive surgery, 17 glaucoma, 18 retinal States, Denmark, Manitoba (Canada), and Barcelona disease, 19 myopia, 20 low-vision rehabilitation, 21 uveitis, 22 (Spain). and ARMD. 23 Among other outcomes variables, a measure of vi- In the International Cataract Surgery Outcomes sual functioning was included in these studies. Tradi- Study, we examined the functional outcomes of cataract tionally, we rely on well-known objective tests to surgery. A logistic regression analysis showed no differdescribe the visual status of patients. These include ence in the odds of achieving an optimal visual funcvisual acuity, refraction, contrast sensitivity, glare, color tional outcome (VF-14 score 95 or higher) among vision, and visual field. Each test can describe details Denmark, Spain, and North America. These results of the anatomic or functional outcomes of surgery. indicate that high-quality cataract management is per- However, it is difficult to infer how various combina- formed at all 4 sites. This was observed despite pretions of subnormal results of these tests affect complex viously reported differences in organization of care, 7 social functions that rely on visual capability, such as preoperative testing, 8 characteristics of predominate anshopping or driving. To address this issue, self-report esthetic and surgical techniques, 7,8 indications for surinstruments such as the VF-14 3 and the Activities of gery, 24 and rates of complications. 10 In another paper, Daily Vision Scale 4 were developed. The most recently we report that the odds of achieving an optimal visual introduced instrument is the National Eye Institute acuity outcome (Snellen 0.67 or better) did not vary Visual Function Questionnaire. 5 The use of these instru- significantly among the 4 sites after controlling for differences ments is recommended by the WHO (WHO resolu- in patient case mix. 9 However, in both studies, J CATARACT REFRACT SURG VOL 29, NOVEMBER

6 Table 3. Results of logistic regression showing associations between Table 4. Number of patients reporting suboptimal visual functioning multiple preoperative patient characteristics and the risk of having outcomes (VF-14 score 95) after surgery in both eyes despite optimal suboptimal postoperative visual function (VF-14 score 95). visual acuity outcomes (n 211). Figures show results if 0.50 or 0.67 were chosen as the cut point for optimal visual acuity outcomes. Characteristic Odds Ratios 95% CI P Value Number (%) Site Postop VF-14 United States 1.00 Ref Parameter Score 95 Manitoba Visual acuity 0.50 Denmark Visual acuity 0.50 in both eyes (n 155) 58 (37) Barcelona Visual acuity 0.50 in 1 eye only (n 30) 15 (50) Sex Visual acuity 0.50 in both eyes (n 24) 13 (54) Female 1.00 Ref Missing data (n 2) Male Visual acuity 0.67 Age (y) Visual acuity 0.67 in both eyes (n 130) 45 (35) 50 to Ref Visual acuity 0.67 in 1 eye only (n 38) 21 (55) 60 to Visual acuity 0.67 in both eyes (n 41) 20 (49) 70 to Missing data (n 2) SIP 1 unit increase* Preoperative VA Ref used a VF-14 score of 95 as an indicator of successful or optimal postoperative visual function. However, sensitivity testing was performed using more stringent cut 0.20 to points. Insignificant changes were seen when a VF to score of 100 was used as cut point (data not shown) and linear regression was performed (data not shown). This indicates that our results are robust to the defini- 1 unit increase tion of optimal functional outcomes. It is well accepted that both objective (visual acuity) Normal 1.00 Ref and subjective (visual function) criteria should be met ARMD before surgery is performed. However, to evaluate out- Not assessable preop comes, visual acuity is often reported as the single outcome measure. The VF-14 indicates whether the patient Preoperative VF-14 score Macular status Other comorbidity No 1.00 Ref is capable of performing activities that are dependent Yes on vision. In our study, 37% of patients with an optimal CI confidence interval; Ref reference group; SIP Sickness Impact visual acuity outcome in both eyes (Snellen 0.50 or Profile; VA visual acuity better) still reported visual function impairment. Similar *Increasing score indicates poorer general health status results were seen when a cut point of Snellen 0.67 Increasing score indicates better visual function or better was considered as the optimal visual acuity outcome, supporting the robustness of the conclusion. a comparison of uncontrolled outcomes data showed The results imply that a VF-14 score can identify pa- significant differences among sites. This is important tients who still have visual function impairments despite when examining reports from national or cross-national what might seem an optimal anatomic outcome. Some quality surveillance databases as these data might not of these patients would probably have been identified if be controlled for differences in case mix. a full-scale ophthalmic examination had been performed In most patients with cataract, the aim of surgery that included tests for visual field, glare, color vision, is to restore normal visual function. In the analyses, we contrast sensitivity, reading capability, and cortical defi J CATARACT REFRACT SURG VOL 29, NOVEMBER 2003

7 cits. However, this battery of tests would be time con- ating the benefits of cataract surgery in a public suming and it would still be difficult to tell how various health setting. combinations of suboptimal test results affect activities of daily living. Scoring the VF-14 takes approximately References 10 minutes and can be done by the patient alone. 1. WHO International Classification of Functioning, Dis- Visual functioning instruments focus on the social ability and Health. Geneva, World Health Organization, consequences of visual impairment. 1 This kind of infor (ICIDH-2) mation might be especially important in studies examintice 2. American Academy of Ophthalmology. Preferred Prac- Patterns. Cataract in the Adult Eye. San Francisco, ing the benefits of surgery from a public health CA, AAO, 2001 viewpoint and can be relevant in a discussion of prioriti- 3. Steinberg EP, Tielsch JM, Schein OD, et al. The VFzation of health care. We suggest that changes in visual 14; an index of functional impairment in patients with acuity as well as in visual function be reported in any cataract. Arch Ophthalmol 1994; 112: study evaluating the benefits of cataract surgery. 4. Mangione CM, Phillips RS, Seddon JM, et al. Develop- A strength of our study was the common design ment of the Activities of Daily Vision Scale. A measure of visual functional status. Med Care 1992; 30: and use of common instruments for data collection at 5. Mangione CM, Berry S, Spritzer K, et al. Identifying the 4 international sites. Comparable information on the content area for the 51-item National Eye Institute patient characteristics allowed us to control for differ- Visual Function Questionnaire; results from focus ences in the case mix of patients. Nonresponder analyses groups with visually impaired persons. Arch Ophthalmol in the United States and Denmark did not reveal recruit- 1998; 116: ment bias. 25,26 A bias might be introduced if a similar 6. Cataract Management Guideline Panel. Cataract in Adults: Management of Functional Impairment. Agency degree of visual impairment were coded differently in for Health Care Policy and Research pub. no patients of different cultural backgrounds. However, in Rockville, MD, Department of Health and Human a previous study of validity, we found this was not the Services, 1993 case. 13 The Spanish and Danish versions of the VF Norregaard JC, Schein OD, Anderson GF, et al. Internawere developed by a translation back-translation techtients tional variation in ophthalmologic management of pa- with cataract; results from the International nique, the gold standard for translating an instrument. 27 Cataract Surgery Outcomes Study. Arch Ophthalmol Similar internal consistency, correlation with other vari- 1997; 115: ables of vision, and correlation with a general health 8. Norregaard JC, Schein OD, Bellan L, et al. International score (SIP) were observed at the 4 sites. The other variation in anesthesia care during cataract surgery; results variables of vision were visual acuity in the operated from the International Cataract Surgery Outcomes eye and better eye, cataract symptoms, global satisfac- Study. Arch Ophthalmol 1997; 115: Norregaard JC, Hindsberger C, Alonso J, et al. Visual tion with vision, and trouble with vision. These results outcomes of cataract surgery in the United States, Canindicate no cross-cultural bias in the scoring system. 13 ada, Denmark, and Spain; report from the International Cataract Surgery Outcomes Study. Arch Ophthalmol 1998; 116: Conclusion 10. Norregaard JC, Bernth-Petersen P, Bellan L, et al. Intraoperative We examined the postoperative VF-14 scores in clinical practice and risk of early complications different health care settings in 4 countries. After con- after cataract extraction in the United States, Canada, Denmark, and Spain. Ophthalmology 1999; 106:42 48 trolling for patient case mix, the odds of achieving an 11. de Bruin AF, de Witte LP, Stevens F, Diederiks JP. optimal visual function outcome were similar among Sickness Impact Profile: the state of the art of a generic the 4 sites. This was observed despite gross differences functional status measure. Soc Sci Med 1992; 35:1003 in management of care. Age, sex, and coexisting ocular 1014 pathology were important predictors of visual function 12. Moseley MJ, Jones HS. Visual acuity: calculating appro- outcomes. Despite achieving what seemed an optimal priate averages. Acta Ophthalmol 1993; 71: Alonso J, Espallargues M, Andersen TF, et al. Internasurgical outcome, one third of patients still had visual tional applicability of the VF-14; an index of visual disabilities affecting everyday life. The VF-14 might function in patients with cataract. Ophthalmology help reveal these disabilities, especially in studies evalu- 1997; 104: J CATARACT REFRACT SURG VOL 29, NOVEMBER

8 14. Cassard SD, Patrick DL, Damiano AM, et al. Reproduc- 24. Norregaard JC, Bernth-Petersen P, Alonso J, et al. Variaibility and responsiveness of the VF-14; an index of tion in indications for cataract surgery in the United functional impairment in patients with cataract. Arch States, Denmark, Canada, and Spain: results from the Ophthalmol 1995; 113: International Cataract Surgery Outcomes Study. Br J 15. Steinberg EP, Tielsch JM, Schein OD, et al. National Ophthalmol 1998; 82: study of cataract surgery outcomes; variation in 4-month 25. Schein OD, Steinberg EP, Javitt JC, et al. Variation in postoperative outcomes as reflected in multiple outcomes cataract surgery practice and clinical outcomes. Ophthalmeasures. Ophthalmology 1994; 101: ; dismology 1994; 101: cussion by DM O Day, Nørregaard JC, Bernth-Petersen P, Andersen TF. Visual 16. Musch DC, Farjo AA, Meyer RF, et al. Assessment of impairment and general health among Danish cataract health-related quality of life after corneal transplantation. patients; results from the Danish Cataract Surgery Out- Am J Ophthalmol 1997; 124:1 8 comes Study. I. Acta Ophthalmol (Scand) 1996; 17. Brunette I, Gresset J, Boivin J-F, et al. Functional outcome and satisfaction after photorefractive keratectomy. 74: Part I: development and validation of a survey questionhealth outcomes through international comparisons. 27. Anderson GF, Alonso J, Kohn LT, Black C. Analyzing naire. Ophthalmology 2000; 107: Gutierrez P, Wilson MR, Johnson C, et al. Influence of Med Care 1994; 32: glaucomatous visual field loss on health-related quality of life. Arch Ophthalmol 1997; 115: From the University Eye Clinic, Frederiksberg Hospital (Norregaard, 19. Linder M, Chang TS, Scott IU, et al. Validity of the Bernth-Petersen), and Institute of Public Health, Faculty of Health Visual Function Index (VF-14) in patients with retinal Science, University of Copenhagen (Norregaard, Andersen), Copenhadisease. Arch Ophthalmol 1999; 117: gen, Denmark; Health Services Research Unit, Institut Municipal 20. Rose K, Harper R, Tromans C, et al. Quality of life in d Investigació Mèdica (Alonso), Barcelona, Spain; and Center for Hosmyopia. Br J Ophthalmol 2000; 84: pital Finances and Management, Johns Hopkins University (Anderson), 21. Scott IU, Smiddy WE, Schiffman J, et al. Quality of Baltimore, Maryland, USA. life of low-vision patients and the impact of low-vision Supported by a grant from the Agency for Health Care Policy and services. Am J Ophthalmol 1999; 128:54 62 Research (HS 07085), Rockville, Maryland, USA. Danish study also 22. Schiffman RM, Jacobsen G, Whitcup SM. Visual func- supported by the John & Birthe Meyer Foundation, Danish Eye Research tioning and general health status in patients with uveitis. Foundation, Danish Medical Research Council, Health Insurance Arch Ophthalmol 2001; 119: Fond, and Denmark Health Foundation, Copenhagen, Denmark. 23. Mackenzie PJ, Chang TS, Scott IU, et al. Assessment of Spanish study also supported by grants from the Agència d Avaluació de vision-related function in patients with age-related macular Tecnologica Mèdica de Catalunya and Fondo de Investigación Sanitaria degeneration. Ophthalmology 2002; 109: (No 95/0229), Barcelona, Spain J CATARACT REFRACT SURG VOL 29, NOVEMBER 2003