Secondary Logo

Journal Logo

Article

Impact of cataract surgery on self-reported visual difficulties

Comparison with a no-surgery reference group

McGwin, Gerald Jr. MS, PhDa,b,c,*; Scilley, Kay PhDa; Brown, Jay MDa; Owsley, Cynthia PhD, MSPHa

Author Information
Journal of Cataract & Refractive Surgery: May 2003 - Volume 29 - Issue 5 - p 941-948
doi: 10.1016/S0886-3350(02)01846-1
  • Free

Abstract

By age 75 years, almost 50% of adults in the United States have early cataract and approximately one quarter have more advanced cataract.1,2 Cataract can seriously compromise visual acuity and contrast sensitivity and can increase disability glare problems.3 Compared with older adults free of cataract, patients with cataract report significant difficulties with the visual tasks of everyday living (eg, reading, driving, social)4–6 and experience problems with emotional well-being and social functioning.4,5

It is well established that cataract surgery and intraocular lens implantation are very successful in improving vision. Given cataract's high prevalence in the elderly population, cataract extraction has become the most common surgical procedure in Medicare beneficiaries in the U.S.7 Since the 1980s, several outcomes studies have examined the impact of cataract surgery on self-reported difficulties with the visual tasks of everyday living.8–15 These studies collectively show that after surgery, patients typically report substantial improvement in their ability to perform daily visual tasks and in their physical functioning, emotional well-being, and satisfaction with their vision.

Previous studies had preoperative–postoperative designs and did not incorporate a nonsurgical reference group; that is, patients with cataract who did not elect surgical intervention yet who completed a visual difficulty questionnaire twice over the same timeframe. The inclusion of a group of patients without intervention is a more direct method of evaluating the effect of surgery on self-reported difficulties.

In this study, we addressed how cataract surgery affects older adults' self-reported visual difficulties compared with those who have cataract but who decline surgery. In addition, we examined to what extent improvements in acuity, contrast sensitivity, and disability glare in those who have cataract surgery are associated with self-reported improvements in the ability to perform visual tasks.

Patients and Methods

Patients were recruited from 12 eyecare practices in Birmingham, Alabama, by a consecutive chart review over 6 months for the Impact of Cataracts on Mobility (ICOM) project.6,16,17 This prospective study of the impact of cataract surgery on driving safety and habits provided the opportunity to collect data relevant to the research questions addressed here. The surgeons at all practices used for recruitment had operating privileges at the Callahan Eye Foundation Hospital, a university-affiliated eye center. They had no role in selecting patients during recruitment.

Inclusion criteria were at least 55 years old; cataract in 1 or both eyes with a visual acuity of 20/40 or worse (best corrected, distance) as indicated in the medical record; no previous cataract surgery in either eye; during the patient's last eyecare visit, an ophthalmologist or optometrist recommended cataract surgery for reduced vision; health insurance, Medicare, and/or a private plan; and living independently in the community. The primary cause of visual loss had to be cataract as judged by an ophthalmologist or optometrist. Exclusion criteria were amblyopia, use of a wheelchair for mobility, and a diagnosis of dementia, Parkinson's disease, psychosis, or illness that would likely preclude a 1-year follow-up visit.

Candidates for enrollment were contacted by their ophthalmologist or optometrist in a letter describing the study; this was followed by a telephone call from the study coordinator. Those who agreed to participate were scheduled for an appointment at the Clinical Research Unit, Department of Ophthalmology, University of Alabama at Birmingham (UAB). The Institutional Review Board at UAB approved the study protocol.

Protocol

After the purpose of the study was explained, each patient was invited to sign a document of informed consent before enrolling. The baseline protocol was as follows for all enrollees: For those who elected cataract surgery, the baseline visit was before the first-eye surgery date. A questionnaire, the Activities of Daily Vision Scale (ADVS), was used to assess the extent to which patients experienced difficulty with the visual activities of daily living.18 The ADVS was developed for use with cataract patients to evaluate the impact of cataract surgery and has good reliability and validity.12,18 It consists of 22 items addressing visual difficulties in everyday tasks. Responses are on a 5-point scale ranging from “no difficulty” to “unable to do the activity because of visual problems.” Item responses are organized into 5 subscales: daytime driving, night driving, near vision, far vision, and glare disability. Each subscale is scored between 100 (no visual difficulty) and 0 (inability to perform the activity because of visual difficulty). The recommended ADVS scoring procedure was used18; that is, when the patient did not complete at least half the items on a subscale, no score was computed for that subscale. An overall ADVS score (based on all the individual items, not the subscales) is also expressed on a scale of 0 to 100.

In addition to the ADVS, 3 tests of visual function were carried out for each eye separately using habitual correction (ie, the correction that patients used in everyday activities). Distance acuity was measured using the Early Treatment Diabetic Retinopathy Study letter chart and its standard protocol and was expressed in logMAR notation.19,20 Contrast sensitivity was measured with the Pelli-Robson contrast sensitivity chart and its standard protocol and was expressed as log contrast sensitivity.21,22 Disability glare was estimated with the Brightness Acuity Tester (BAT) as the patient viewed the Pelli-Robson chart and was defined as the Pelli-Robson score without the BAT minus the Pelli-Robson score with the BAT.23,24

Demographic data (age, sex, race, education) were confirmed through an interview. An estimate of general health was provided by a questionnaire that asked about the presence or absence of health problems in 17 areas, yielding an index of the total number of comorbid medical conditions present.6

Statistical Analysis

Demographic and health characteristics of cataract patients who had surgery and those who did not have surgery were compared using chi-square and t tests for categorical and continuous variables, respectively. Visual function characteristics and ADVS scores were obtained from 2 time points for each patient. In the surgery group, these 2 time points were the presurgery visit (baseline) and the visit after surgery (visit 2). These chronological measures allowed for the calculation of absolute differences by subtracting the presurgery measures from the postsurgery measures. In more than 90% of patients, the postsurgery measures were taken from data obtained at visit 2 (first annual follow-up); in the remaining patients, the postsurgery score was taken from the 2-year visit because they were unable to attend the first annual visit. In the no-surgery group, absolute differences were obtained by subtracting visit 2 measures from the baseline measures. The period between the baseline and visit 2 was approximately 1 year, as in the surgery group.

To determine whether, within each group, there was a significant change in visual function measures and ADVS scores, each set of variables was compared using the paired t test. To determine whether the groups experienced equivalent changes in visual function measures and ADVS scores, absolute differences between the groups were compared using the t test. To further compare the extent of change in ADVS scores between the groups, change scores were calculated for the ADVS total score and subscales using the technique described by Vickers and Altman.25 Briefly, in studies in which subjects provide at least 2 measurements of the same variable, follow-up measurements are adjusted for baseline measurements to provide measures of change that are independent of baseline values. In the context of this study, postsurgery or visit 2 ADVS scores were used as the dependent variable in a linear regression model, with baseline ADVS scores and a group variable serving as independent variables. These regression models were also constructed adjusting for the potentially confounding effects of age, sex, race, education, number of chronic medical conditions, and baseline visual acuity (better and worse eye), contrast sensitivity (better and worse eye), and disability glare (better and worse eye).

To evaluate which characteristics were associated with changes in ADVS scores in the surgery group, Spearman correlation coefficients for the association between ADVS change scores and absolute differences in visual function characteristics were calculated. Multiple linear regression was also used to determine what characteristics had an independent association with ADVS change scores. The r2 value was computed for each model to examine the percentage of variance accounted for by the variables.

Results

Table 1 shows the baseline demographic and health characteristics of patients in the surgery and no-surgery groups. The groups were similar in the distribution of age and years of education completed and the number of medical comorbidities. White patients, women, and those with no ocular comorbidities were more likely to choose surgery. In the surgery group, 56.4% of patients had surgery in both eyes during the 1-year observation period.

Table 1
Table 1:
Baseline demographic and health characteristics of patients who had and did not have cataract surgery

At baseline, visual acuity in the better eye in the surgery group was approximately 1 line worse than in the better eye in the no-surgery group (Table 2). In the worse eye, the acuity differential between the 2 groups was 2 lines. Baseline contrast sensitivity and disability glare were also worse in the surgery group than in the no-surgery group. Table 2 also shows the mean differences (follow-up minus baseline) in visual function variables and ADVS scores in both groups. Comparisons between the differences in visual function in the groups were all significant. In the surgery group, visual acuity, contrast sensitivity, and disability glare improved postoperatively. In the no-surgery group, vision declined slightly or remained the same.

Table 2
Table 2:
Baseline and follow-up visual function and ADVS characteristics of patients who had and did not have cataract surgery

In the surgery group, the ADVS scores for all subscales after surgery were significantly higher than before surgery; in the no-surgery, there was no difference in the ADVS scores between baseline and visit 2 (Table 2 and Figure 1). The lowest mean ADVS subscale score at baseline in the surgery group was for night driving (53), and the highest mean scores were for day driving (76) and near vision (75); a similar pattern was observed in the no-surgery group. The surgery group had significantly greater differential changes in ADVS scores (toward improvement) than the no-surgery group. Analyses of the changes in scores revealed that after adjustment for baseline characteristics, the surgery group had a significantly greater change (in the direction of improvement) in ADVS scores, both overall and subscales, than the no-surgery group.

Figure 1.
Figure 1.:
(McGwin) Mean ADVS subscale scores and overall ADVS score in the surgery group before and after cataract surgery and in the no-surgery reference group over the same timeframe.

Table 3 shows the correlations in the surgery group between ADVS change scores and changes in visual function characteristics. The ADVS change scores were significantly correlated with changes in visual acuity, contrast sensitivity, and disability glare independent of age, sex, race, education, chronic medical conditions, and ocular comorbidities. In the surgery group, multiple linear regression models showed that visual acuity in the first-surgery eye had a significant, independent association with the change in the overall ADVS score and with the change in the night driving and glare disability subscales (Table 4). Change in contrast sensitivity was associated with change in the night driving subscale only. Change in disability glare in the second-surgery eye was significantly associated with the overall ADVS change score as well as the change scores of the night driving, near vision, and glare disability subscales. The change in vision scores (adjusted for baseline demographic and health variables) accounted for a sizable portion of the variance in change scores on the night driving (60%) and near vision (49%) ADVS subscales. The variance accounted for on the other subscales was of a more modest magnitude (19% to 25%).

Table 3
Table 3:
Spearman partial correlation coefficients* for association between ADVS change scores and changes in visual function characteristics in the surgery group (N = 156)
Table 4
Table 4:
The t test statistics from multiple regression models for the independent association between ADVS change scores and visual function change characteristics in the surgery group (N = 156) adjusted for age, sex, race, education, number of chronic medical conditions, and ocular comorbidities

Discussion

Unlike earlier studies of cataract surgery and self-reported outcomes,8–15 ours included a nonsurgical reference group to compare and evaluate the impact of cataract surgery on patient-reported visual task difficulty. Scores on the ADVS subscales in the surgery group improved substantially after surgery, between 15 and 21 points, which agrees with findings in previous work.12 This is in sharp contrast to patients who declined surgery, whose scores were unchanged over the same annual timeframe. The positive impact of surgery was highly significant even when the baseline differences between the 2 groups were taken into account.

These data are also helpful in understanding the characteristics of cataractous older adults who elect to have cataract surgery versus those who decline it. All patients in this study had health insurance that covered cataract surgery; thus, the lack of health insurance, noted in population-based studies as an important factor in understanding who has cataract surgery,26 was not a reason for failing to have the procedure in our cohort. Patients who elected surgery in our study were more likely to be white, female, and have more vision impairment, consistent with findings in an earlier report.27 Our study further shows that compared to those who choose surgery, patients who decide against it do not believe they have serious difficulty in the visual tasks of daily living. This finding was striking across an array of activity domains (ie, subscales) but was particularly pronounced for driving. Those who elected to have surgery scored approximately 20 points lower on the day and night driving subscales than those who declined surgery. This implies that driving problems may be a common motivator for cataract surgery and underscores the high value older adults place on access to driving.28 Another analysis of the ICOM project6 revealed that the ophthalmologist infrequently listed driving in any participant's medical records as a reason for electing surgery; rather, reading and work task difficulties were listed as the presenting complaints.17 Ironically, when patients were asked directly during the administration of the ADVS, driving emerged as the major domain in which they cited serious problems.

What types of visual functional improvement as a result of cataract surgery are related to improvements in ADVS scores? Previous work on the ADVS focused on the role of acuity in mediating increased ADVS scores after surgery, showing that the magnitude of acuity improvement from presurgery to postsurgery was associated with increases in the ADVS score.12 The present study goes further in showing that acuity alone is not responsible for ADVS score improvement. Improvements in contrast sensitivity and reductions in disability glare were also independent contributors to reductions in self-reported visual task difficulty. These results highlight the need to consider more than spatial resolution in understanding the underpinnings of everyday visual performance, a finding that is being increasingly born out in clinical and epidemiological studies using self-reported and task-performance outcomes.29–35

References

1. Kahn HA, Leibowitz HM, Ganley JP, et al. The Framingham Eye Study. I. Outline and major prevalence findings. Am J Epidemiol 1977; 106:17-32
2. Klein BEK, Klein R, Linton KLP. Prevalence of age-related lens opacities in a population; the Beaver Dam Eye Study. Ophthalmology 1992; 99:546-552
3. Rubin GS, Adamsons IA, Stark WJ. Comparison of acuity, contrast sensitivity, and disability glare before and after cataract surgery. Arch Ophthalmol 1993; 111:56-61
4. Mangione CM, Lee PP, Pitts J, et al. Psychometric properties of the National Eye Institute Visual Function Questionnaire (NEI-VFQ). Arch Ophthalmol 1998; 116:1496-1504
5. Mangione CM, Lee PP, Gutierrez PR, et al. Development of the 25-item National Eye Institute Visual Function Questionnaire. Arch Ophthalmol 2001; 119:1050-1058
6. Owsley C, Stalvey B, Wells J, Sloane ME. Older drivers and cataract: driving habits and crash risk. J Gerontol A Biol Med Sci 1999; 54A:M203-M211
7. Steinberg EP, Javitt JC, Sharkey PD, et al. The content and cost of cataract surgery. Arch Ophthalmol 1993; 111:1041-1049
8. Bernth-Petersen P. Outcome of cataract surgery I. A prospective, observational study. Acta Ophthalmol 1982; 60:235-242
9. Applegate WB, Miller ST, Elam JT, et al. Impact of cataract surgery with lens implantation on vision and physical function in elderly patients. JAMA 1987; 257:1064-1066
10. Brenner MH, Curbow B, Javitt JC, et al. Vision change and quality of life in the elderly; response to cataract surgery and treatment of other chronic ocular conditions. Arch Ophthalmol 1993; 111:680-685
11. Javitt JC, Brenner MH, Curbow B, et al. Outcomes of cataract surgery; improvement in visual acuity and subjective visual function after surgery in the first, second, and both eyes. Arch Ophthalmol 1993; 111:686-691
12. Mangione CM, Phillips RS, Lawrence MG, et al. Improved visual function and attenuation of declines in health-related quality of life after cataract extraction. Arch Ophthalmol 1994; 112:1419-1425
13. Steinberg EP, Tielsch JM, Schein OD, et al. National study of cataract surgery outcomes: variation in 4-month postoperative outcomes as reflected in multiple outcome measures. Ophthalmology 1994; 101:1131-1140; discussion by DM O'Day, 1140–1141
14. Javitt JC, Steinberg EP, Sharkey P, et al. Cataract surgery in one eye or both; a billion dollar per year issue. Ophthalmology 1995; 102:1583-1592; discussion by DM O'Day, 1592–1593
15. Elliott DB, Patla A, Bullimore MA. Improvements in clinical and functional vision and perceived visual disability after first and second eye cataract surgery. Br J Ophthalmol 1997; 81:889-895
16. Owsley C, Stalvey BT, Wells J, et al. Visual risk factors for crash involvement in older drivers with cataract. Arch Ophthalmol 2001; 119:881-887
17. Owsley C, McGwin GJ Jr, Sloane M, et al. Impact of cataract surgery on motor vehicle crash involvement by older adults. JAMA 2002; 288:841-849
18. Mangione CM, Phillips RS, Seddon JM, et al. Development of the “Activities of Daily Vision Scale”; a measure of visual functional status. Med Care 1992; 30:1111-1126
19. Ferris FL III, Kassoff A, Bresnick GH, Bailey I. New visual acuity charts for clinical research. Am J Ophthalmol 1982; 94:91-96
20. Ferris FL III, Sperduto RD. Standardized illumination for visual acuity testing in clinical research. Am J Ophthalmol 1982; 94:97-98
21. Pelli DG, Robson JG, Wilkins AJ. The design of a new letter chart for measuring contrast sensitivity. Clin Vis Sci 1988; 2:187-199
22. Elliott DB, Bullimore MA, Bailey IL. Improving the reliability of the Pelli-Robson contrast sensitivity test. Clin Vis Sci 1991; 6:471-475
23. Holladay JT, Prager TC, Trujillo J, Ruiz RS. Brightness acuity test and outdoor visual acuity in cataract patients. J Cataract Refract Surg 1987; 13:67-69
24. Elliott DB, Bullimore MA. Assessing the reliability, discriminative ability, and validity of disability glare tests. Invest Ophthalmol Vis Sci 1993; 34:108-119
25. Vickers AJ, Altman DG. Statistics notes: analysing controlled trials with baseline and follow up measurements. BMJ 2001; 323:1123-1124
26. Broman AT, Munoz B, Rodriguez J, et al. Factors associated with accessing cataract surgery in a population-based study of Hispanics: Proyecto VER. ARVO abstract 2869. Invest Ophthalmol Vis Sci 2001; 42(4):S534
27. Lee P. Assessing quality and utilization patterns in health care delivery systems [editorial]. Arch Ophthalmol 1998; 116:234-235
28. Jette AM, Branch LG. A ten-year follow-up of driving patterns among the community-dwelling elderly. Hum Factors 1992; 34:25-31
29. Alexander MF, Maguire MG, Lietman TM, et al. Assessment of visual function in patients with age-related macular degeneration and low visual acuity. Arch Ophthalmol 1988; 106:1543-1547
30. Rubin GS, Bandeen Roche K, Prasada-Rao P, Fried LP. Visual impairment and disability in older adults. Optom Vis Sci 1994; 71:750-760
31. Rubin GS, Bandeen-Roche K, Huang G-H, et al. The association of multiple visual impairments with self-reported visual disability: SEE Project. Invest Ophthalmol Vis Sci 2001; 42:64-72
32. Sloane ME, Ball K, Owsley C, et al. The Visual Activities Questionnaire: developing an instrument for assessing problems in everyday visual tasks. In: Noninvasive Assessment of the Visual System Technical Digest. Washington, DC, Optical Society of America, 1992; 1:26-29
33. Scilley K, Jackson GR, Cideciyan AV, et al. Early age-related maculopathy and self-reported visual difficulty in daily life. Ophthalmology 2002; 109:1235-1242
34. Owsley C, McGwin G Jr, Sloane ME, et al. Timed instrumental activities of daily living tasks: relationship to visual function in older adults. Optom Vis Sci 2001; 78:350-359
35. Jampel HD, Friedman DS, Quigley H, Miller R. Correlation of the binocular visual field with patient assessment of vision. Invest Ophthalmol Vis Sci 2002; 43:1059-1067
© 2003 by Lippincott Williams & Wilkins, Inc.