- Email: [email protected]
Strategy to reduce the number of patients perceiving impaired visual function after cataract surgery1
Strategy to reduce the number of patients perceiving impaired visual function after cataract surgery Mats Lundstro¨m, MD, PhD, Klas Go¨ran Brege, MD, Ingrid Flore´n, MD, PhD, Ulf Stenevi, MD, PhD, William Thorburn, MD, PhD
Purpose: To reduce the number of patients who perceive more difficulties performing daily life activities 6 months after cataract extraction than before surgery. Setting: Surgeons at 4 surgical units participating in the yearly outcome studies organized by the Swedish National Cataract Register. Methods: This study comprised surgical outcomes data and completed Catquest results before and after surgery collected from consecutive patients during a 1-month period yearly since 1995. The reasons for a no-benefit outcome from 1995 to 1997 were identified. During the 1-month study period in 1999, a strategy was launched to reduce postoperative anisometropia and disturbances from cataract in the fellow eye through better surgical planning. Results: The percentage of patients with a no-benefit outcome who had anisometropia or cataract in the fellow eye as a probable reason for the outcome decreased from 27.3% and 13.0%, respectively, in the 1995 to 1997 study to 10.5% and 10.5%, respectively, in the 1999 study. Other reasons for a no-benefit outcome such as ocular co-morbidity or few preoperative problems increased in frequency, presumably as a result of a change in case mix. Conclusions: A strategy to reduce the number of patients perceiving more difficulties in performing daily life activities after cataract extraction than before surgery was tested. The number of patients with reasons for a poor outcome that the study focused on was reduced. Patients who gave reasons for a poor outcome other than anisometropia or cataract in the fellow eye increased in frequency, probably as a result of a change in case mix. J Cataract Refract Surg 2002; 28:971–976 © 2002 ASCRS and ESCRS
P
atients’ assessment of their visual function in daily life is an important outcomes measure of cataract surgery.1,2 Different methods to achieve this measure have been suggested.1,3–5 In the Swedish National Cataract Register (NCR), the Catquest questionnaire has been used regularly since 1995.5 Catquest describes the outcomes of surgery using 5 levels of benefit.6 The worst is a no-benefit outcome, which means that the patient
Accepted for publication September 19, 2001. Reprint requests to Mats Lundstro¨m, MD, PhD, Department of Ophthalmology, Blekinge Hospital, S-371 37 Karlskrona, Sweden. © 2002 ASCRS and ESCRS Published by Elsevier Science Inc.
reported more difficulties performing 7 daily life activities 6 months after cataract extraction than before. The percentage of patients having a no-benefit outcome in yearly studies in Sweden since 1995 has been fairly stable, approximately 8% to 9%.7 However, there has been considerable variation in outcomes between years at the surgical units participating in these studies. This variation is most likely the result of differences in indications for surgery and case mixes caused by a relatively low number of patients during each study period. The concept of understanding variation that Nolan and Provost8 describe has been a guiding rule in interpreting this variation. 0886-3350/02/$–see front matter PII S0886-3350(01)01268-8
PATIENT-PERCEIVED VISUAL IMPAIRMENT AFTER CATARACT SURGERY
Table 1. Percentage of patients with a no-benefit outcome. Year of Surgery
Surgical Unit
1995 (N ⴝ 292)
1
11.0
2
8.2
3
13.3
4 All
1996 (N ⴝ 248)
1997 (N ⴝ 230)
1995–97 (N ⴝ 770)
13.0
9.3
11.2
6.0
10.9
6.1
8.3
8.4
6.7
5.6
8.7
9.8
12.8
17.2
7.3
12.6
14.2
11.6
11.7
7.0
10.2
9.7
An overall reduction in the number of patients perceiving more difficulties after cataract extraction is, irrespective of the reason, a desirable improvement in clinical outcomes. Four surgical units (Eskilstuna, Gothenburg, Karlskrona, Lund) participating in the NCR outcome studies started a project in 1998 to improve their clinical results as defined by Catquest.9 The structure of this plan to achieve clinical improvement partly followed the ideas of Batalden and coauthors.10 The 4 surgical units had participated in the NCR outcomes studies since 1995. Their results from 1995 to 1997 as defined by Catquest are shown in Table 1. In 1998, a retrospective study was performed to identify the reasons for a no-benefit outcome from 1995 to 1997.9 These reasons are shown in Table 2. The next step was to identify which reasons for a no-benefit outcome could be improved. The largest group of patients with a no-benefit outcome had a coexisting eye disorder in the eye to be operated on as a probable reason. There is a lack of knowledge about which patients with a certain disorder, for instance macular degeneration, benefit from cataract extraction. Until greater knowledge about patients with co-existing eye disorders is achieved, a change in surgical indications cannot and should not be suggested. Another large group of patients had anisometropia as a probable reason for the poor outcome. Even if the anisometropia were deliberate (ie, waiting for surgery in the fellow eye), the presence of disturbing anisometropia 6 months after surgery must be considered poor care. It should be possible to reduce the number of patients in this group through better surgical planning. Another group of patients had a disturbing cataract in the fellow eye. It should also be possible to reduce the number of patients in this group through better surgical strategy. 972
1999 (N ⴝ 390)
The outcome was judged poor in some cases in which there were few difficulties preoperatively. This means that the instrument could not measure difficulties before surgery and therefore could not measure any improvement. This is a result of the indications for surgery and/or measurement problems,11 not necessarily poor care. Other reasons for a poor outcome included complications during and after surgery; in some cases, the reasons were unknown. Complications of surgery may, of course, be a result of poor care. Reducing the number of complications during and after surgery is a continuous goal at all surgical units, however, and was therefore not specifically included in this project. This report describes the action taken by the 4 surgical units during the 1999 study to reduce the number of patients with a no-benefit outcome after cataract surgery and gives the results achieved.
Table 2. Reasons for a no-benefit outcome. Number (%) 1995–97 Study†
1999 Study‡
Co-existing eye disease in the surgical eye
37 (48.1)
22 (57.9)
Anisometropia
21 (27.3)
4 (10.5)
Disturbances from fellow eye
10 (13.0)
4 (10.5)
Low disability score (few preoperative difficulties)
9 (11.7)
9 (23.7)
Unknown
8 (10.4)
4 (10.5)
Postoperative complication
8 (10.4)
1 (2.6)
Complication during surgery
7 (9.1)
0
Not suitable glasses
5 (6.5)
2 (5.2)
Reason*
*One patient could have more than 1 reason for the poor outcome. † In this study, 77 patients had a no-benefit outcome. ‡ In this study, 38 patients had a no-benefit outcome.
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Results
Table 3. Preoperative conditions. Number (%) 1995–97 Study (N ⴝ 770)
1999 Study (N ⴝ 390)
P Value*
Low pre-operative score sum (⬍9) (⫽few difficulties)
133 (17.3)
83 (21.3)
.097
Best vision better eye, preoperatively ⬍0.5
257 (33.4)
95 (24.4)
.002
Second-eye surgery
250 (32.5)
142 (36.4)
.180
Ocular co-morbidity in the surgical eye
299 (38.8)
157 (40.3)
.639
Variable
*Chi-square test
Patients and Methods Data on all consecutive cataract extractions performed at the 4 surgical units during March 1999 were collected and reported to the NCR according to the routines for participation in the NCR.7 This included a completed Catquest questionnaire by all patients before and 6 months after surgery. The patients scheduled for surgery during the study month were treated using the following guidelines: 1. Patients scheduled for second-eye surgery. Care should be taken to achieve isometropia. Thus, if there is no strong reason to create monovision, the target refraction in the eye to be operated on should be as close as possible to the refraction in the previously operated eye. 2. Patients scheduled for first-eye surgery. In patients with cataract in both eyes, second-eye surgery should be planned within 2 to 3 months (May or June) after first-eye surgery in March if the patient does not object. If there is no or a mild cataract in the second eye and the patient perceives no disturbances from this eye or does not want surgery, only first-eye surgery should be performed. In all patients scheduled for first-eye surgery, the problem of anisometropia should be addressed to ensure isometropia at follow-up.
Surgical outcomes data and completed preoperative and postoperative questionnaires were available for 390 patients at the participating units. During the study month, first-eye surgery was performed in 249 cases and second-eye surgery, in 141 cases. A cataract extraction in the fellow eye during the follow-up (6 months) was performed in 69 cases. Thus, outcomes data were complete for 180 patients having first-eye surgery in March without further surgery during the study period, 69 patients with second-eye surgery 2 to 3 months after surgery in the first eye (in March), and 141 patients having secondeye surgery in March 1999. A no-benefit outcome was noted in 38 cases (9.7% of all surgery). Table 1 shows the percentage of patients with a no-benefit outcome from 1995 through 1999 by surgical unit. The probable reasons for a no-benefit outcome are shown in Table 2. The reasons in 1999 were different from those in previous years, before the new strategy was launched. Anisometropia decreased as a probable reason for a poor outcome, from 27.3% in the previous study (1995 through 1997) to 10.5% in 1999 (P ⫽ .041, Pearson chi square). All patients in the 1999 study (N ⫽ 4) were among those who had first-eye sur-
Table 4. Preoperative visual acuity in the fellow eye before surgery in March. Visual Acuity
Measurement
First-Eye Surgery (n ⴝ 180)
Surgery in Both Eyes* (n ⴝ 69)
Second-Eye Surgery (n ⴝ 141)
25th percentile
0.4
0.3
0.5
Median
0.7
0.5
0.7
75th percentile
0.9
0.6
0.9
*Refers to fellow eye at first-eye surgery.
Figure 1. (Lundstro¨ m) Distribution of the difference in refraction (spherical equivalent) between the 2 eyes in a patient in the first-eye surgery, surgery in both eyes within 6 months, and second-eye surgery groups. The median difference was 0.75 D, 0.60 D, and 0.50 D, respectively, and 60%, 73.9%, and 80.9%, respectively, were within ⫾1.00 D. Within the box is the middle 50% of the values, and the white line represents the median of the distribution. The vertical lines above and below the box indicate the extent of 95% of the values.
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gery in March without further surgery. Progress of cataract in the fellow eye was judged as a probable reason in 13.0% of cases in the previous study and 10.5% in the 1999 study (P ⫽ .704, Pearson chi square). Complications during and after surgery occurred at a much lower frequency in the 1999 study. In contrast, a low disability score sum before surgery and ocular co-morbidity were cited more frequently as reasons for a no-benefit outcome in the 1999 study than in the earlier study. Table 3 shows the case-mix variables in the previous study and the 1999 study. The duration from first-eye surgery in March 1999 to surgery in the fellow eye was within 3 months in 66 of the 69 patients. The mean time between surgery in the first eye and that in the second eye was 2.0 months. Thus, the goal of 2 to 3 months between surgeries was fulfilled in most cases (95.7%). Six patients had bilateral cataract extraction on the same day. These patients are represented only by their first eye but are included in the group having surgery in both eyes during the study period. The patients selected for both first- and second-eye surgery during the study period had a worse preoperative visual acuity in the better eye than in the fellow eye in the group having first-eye surgery only (Table 4). The difference in preoperative visual acuity between eyes having bilateral surgery and those having first-eye surgery was statistically significant (P ⬍ .001, Mann-Whitney U test). In the 1999 study, the mean difference in the final refraction between the 2 eyes was 0.71 diopter (D) ⫾ 0.63 (SD) in patients having bilateral surgery, 1.15 ⫾ 1.25 D in patients having first-eye surgery, and 0.75 ⫾ 0.92 D in patients having second-eye surgery. The distribution of the difference in refraction between eyes in these 3 groups is shown in Figure 1. The difference in values between the group having surgery in 1 eye and that having surgery in both eyes was statistically significant (P ⫽ .006, t test). There was no significant difference in values between patients having second-eye surgery and those having surgery in both eyes. The outcomes as defined by Catquest in patients having first-eye surgery, surgery in both eyes, and second-eye surgery during the 1999 study are shown in Table 5. The outcome was best in patients having surgery in both eyes during the study period; however, the difference among the groups was not statistically significant. 974
Table 5. Outcomes of cataract surgery as defined by Catquest, 1999 study. Percentage Benefit Level Very good Good Moderate Questionable No benefit
First-Eye Surgery (n ⴝ 180)
Surgery in Both Eyes (n ⴝ 69)
Second-Eye Surgery (n ⴝ 141)
38.9
43.5
40.4
4.4
5.8
10.6
35.6
37.7
31.2
9.4
8.7
7.8
11.7
4.3
9.9
Table 6 shows the patients’ satisfaction with their vision 6 months after surgery. Patients having surgery in both eyes during the study period were significantly more satisfied with their vision than patients having first-eye surgery (P ⬍ .001, Mann-Whitney U test) and those having second-eye surgery (P ⫽ .006, MannWhitney U test).
Discussion The aim of this study was to decrease the number of patients perceiving more difficulties 6 months after cataract extraction than before surgery. The reduction from the previous study (1995 through 1997) was small, from 10.5% to 9.7%. Only 1 surgical department had a decrease in the number of patients with a no-benefit outcome in 1999 compared to the previous study. The strategy to achieve our goal was to reduce the number of patients reporting more difficulties after cataract extraction than before because of a disturbing cataract in the fellow eye or anisometropia. These reasons for a nobenefit outcome decreased considerably. The number of Table 6. Patient satisfaction 6 months after surgery in March, 1999 study. Percentage Degree of Satisfaction
First-Eye Surgery (n ⴝ 180)
Surgery in Both Eyes (n ⴝ 69)
Second-Eye Surgery (n ⴝ 141)
Very satisfied
33.9
68.1
51.8
Rather satisfied
40.6
23.2
34.8
Rather dissatisfied
11.1
4.3
6.4
7.2
1.4
4.3
Very dissatisfied
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patients in whom postoperative anisometropia was a probable reason for a no-benefit outcome was significantly lower. By chance, complications during and after surgery as a probable reason for a no-benefit outcome also decreased in frequency. However, other reasons for a worse outcome (eg, ocular co-morbidity, a low preoperative disability score) increased in frequency, resulting in an overall small decrease in no-benefit outcomes. Thus, the case mix was different in the 1999 study than in the previous study. More patients in the 1999 study had an ocular co-morbidity in the eye to be operated on than in the previous study. Ocular co-morbidity in the surgical eye has been correlated with a worse outcome.12,13 Furthermore, patients in the 1999 study had fewer preoperative difficulties than patients in the previous study. Fewer difficulties before surgery result in a low disability score sum, making it harder to measure improvement after surgery.11 The most obvious difference in preoperative conditions, however, was significantly better visual acuity in the better eye in the 1999 study than in the previous study. The measures taken to achieve a low number of no-benefit results were in accordance with the plan. Surgery in the second eye was performed in most cases within 3 months after first-eye surgery. This gave a recovery time of at least 3 months after the last surgery before the patients completed the Catquest questionnaire. In the other 2 groups of patients, the follow-up between surgery and Catquest was 6 months. This difference may have also influenced the results. An important finding in our study was the higher satisfaction with vision of patients who had surgery in both eyes during the study period than of patients who had surgery in 1 eye only. This finding supports the concept of performing second-eye surgery without too much delay in patients with bilateral cataract. The patients selected for surgery in the fellow eye during the follow-up had a significantly worse visual acuity in this eye before first-eye surgery. This indicates that surgery in both eyes within a short interval was performed mainly in patients with cataract and poor vision in both eyes. This finding may also partly explain the low number of patients in this group having a nobenefit outcome. The difference in refraction between the 2 eyes in a patient after surgery was reasonably low. First-eye sur-
gery resulted in the largest difference, which is understandable. In patients having surgery in both eyes, there was also a difference in refraction between the eyes. The lowest median value (0.5 D) and smallest spread of values were in patients having second-eye surgery in March. Patients having surgery in both eyes and those having second-eye surgery had mean values (0.71 D and 0.75 D, respectively) within the limit of what has been reported as a difference between target refraction and final refraction in clinical practice.14
Conclusion A strategy to reduce the number of patients perceiving more visual disability after cataract surgery than before was tested. The number of patients with the targeted reasons for a poor outcome who perceived no benefit decreased considerably. However, patients with other reasons for a poor outcome increased in frequency, with the main reason presumably being changes in the case mix.
References 1. 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 2. Cataract Management Guideline Panel. Cataract in Adults. Management of Functional Impairment. Rockville, MD, U.S. Department of Health and Human Services, Public Health Service, Agency for Health Care Policy and Research, 1993 (AHCPR pub #93– 0542; clinical practice guideline #4) 3. Sloan 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 Series. Washington, DC, Optical Society of America, 1992; 1:26 –29 4. Steinberg EP, Tielsch JM, Schein OD, et al. The VF-14; an index of functional impairment in patients with cataract. Arch Ophthalmol 1994; 112:630 – 638 5. Lundstro¨ m M, Roos P, Jensen S, Fregell G. Catquest questionnaire for use in cataract surgery care: description, validity, and reliability. J Cataract Refract Surg 1997; 23:1226 –1236 6. Lundstro¨ m M, Stenevi U, Thorburn W, Roos P. Catquest questionnaire for use in cataract surgery care: assessment of surgical outcomes. J Cataract Refract Surg 1998; 24:968 –974
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7. Lundstro¨ m M, Stenevi U, Thorburn W. Cataract surgery in the very elderly. J Cataract Refract Surg 2000; 26: 408 – 414 8. Nolan TW, Provost LP. Understanding variation. Quality Progress 1990; May:70 –78 9. Lundstro¨ m M, Brege KG, Flore´n I, et al. Impaired visual function after cataract surgery assessed using the Catquest questionnaire. J Cataract Refract Surg 2000; 26:101–108 10. Batalden PB, Nelson EC, Roberts JS. Linking outcomes measurement to continual improvement: the serial “V” way of thinking about improving clinical care. Jt Comm J Qual Improv 1994; 20:167–180 11. Mangione CM, Orav EJ, Lawrence MG, et al. Prediction of visual function after cataract surgery; a prospectively validated model. Arch Ophthalmol 1995; 113:1305–1311 12. Willerscheidt AB, Healey ML, Ireland M. Cataract surgery outcomes: importance of co-morbidities in case mix. J Cataract Refract Surg 1995; 21:177–181
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13. Lundstro¨ m M, Stenevi U, Thorburn W. Outcome of cataract surgery considering the preoperative situation: a study of possible predictors of the functional outcome. Br J Ophthalmol 1999; 83:1272–1276 14. Lundstro¨ m M, Barry P, Leite E, et al. 1998 European Cataract Outcome Study; report from the European Cataract Outcome Study Group. J Cataract Refract Surg 2001; 27:1176 –1183
From the Departments of Ophthalmology, Blekinge Hospital, Karlskrona (Lundstro¨m), Ma¨ larsjukhuset, Eskilstuna (Brege), Lund University Hospital, Lund (Flore´n), and Sahlgren’s Hospital, Mo¨lndal (Stenevi), and Umeå University Hospital, Umeå (Thorburn), Sweden. Supported by grants from the National Board of Health and Welfare in Sweden and the Federation of County Councils. Karin Johansson provided the numerical information from the database.
J CATARACT REFRACT SURG—VOL 28, JUNE 2002
Purpose: To reduce the number of patients who perceive more difficulties performing daily life activities 6 months after cataract extraction than before surgery. Setting: Surgeons at 4 surgical units participating in the yearly outcome studies organized by the Swedish National Cataract Register. Methods: This study comprised surgical outcomes data and completed Catquest results before and after surgery collected from consecutive patients during a 1-month period yearly since 1995. The reasons for a no-benefit outcome from 1995 to 1997 were identified. During the 1-month study period in 1999, a strategy was launched to reduce postoperative anisometropia and disturbances from cataract in the fellow eye through better surgical planning. Results: The percentage of patients with a no-benefit outcome who had anisometropia or cataract in the fellow eye as a probable reason for the outcome decreased from 27.3% and 13.0%, respectively, in the 1995 to 1997 study to 10.5% and 10.5%, respectively, in the 1999 study. Other reasons for a no-benefit outcome such as ocular co-morbidity or few preoperative problems increased in frequency, presumably as a result of a change in case mix. Conclusions: A strategy to reduce the number of patients perceiving more difficulties in performing daily life activities after cataract extraction than before surgery was tested. The number of patients with reasons for a poor outcome that the study focused on was reduced. Patients who gave reasons for a poor outcome other than anisometropia or cataract in the fellow eye increased in frequency, probably as a result of a change in case mix. J Cataract Refract Surg 2002; 28:971–976 © 2002 ASCRS and ESCRS
P
atients’ assessment of their visual function in daily life is an important outcomes measure of cataract surgery.1,2 Different methods to achieve this measure have been suggested.1,3–5 In the Swedish National Cataract Register (NCR), the Catquest questionnaire has been used regularly since 1995.5 Catquest describes the outcomes of surgery using 5 levels of benefit.6 The worst is a no-benefit outcome, which means that the patient
Accepted for publication September 19, 2001. Reprint requests to Mats Lundstro¨m, MD, PhD, Department of Ophthalmology, Blekinge Hospital, S-371 37 Karlskrona, Sweden. © 2002 ASCRS and ESCRS Published by Elsevier Science Inc.
reported more difficulties performing 7 daily life activities 6 months after cataract extraction than before. The percentage of patients having a no-benefit outcome in yearly studies in Sweden since 1995 has been fairly stable, approximately 8% to 9%.7 However, there has been considerable variation in outcomes between years at the surgical units participating in these studies. This variation is most likely the result of differences in indications for surgery and case mixes caused by a relatively low number of patients during each study period. The concept of understanding variation that Nolan and Provost8 describe has been a guiding rule in interpreting this variation. 0886-3350/02/$–see front matter PII S0886-3350(01)01268-8
PATIENT-PERCEIVED VISUAL IMPAIRMENT AFTER CATARACT SURGERY
Table 1. Percentage of patients with a no-benefit outcome. Year of Surgery
Surgical Unit
1995 (N ⴝ 292)
1
11.0
2
8.2
3
13.3
4 All
1996 (N ⴝ 248)
1997 (N ⴝ 230)
1995–97 (N ⴝ 770)
13.0
9.3
11.2
6.0
10.9
6.1
8.3
8.4
6.7
5.6
8.7
9.8
12.8
17.2
7.3
12.6
14.2
11.6
11.7
7.0
10.2
9.7
An overall reduction in the number of patients perceiving more difficulties after cataract extraction is, irrespective of the reason, a desirable improvement in clinical outcomes. Four surgical units (Eskilstuna, Gothenburg, Karlskrona, Lund) participating in the NCR outcome studies started a project in 1998 to improve their clinical results as defined by Catquest.9 The structure of this plan to achieve clinical improvement partly followed the ideas of Batalden and coauthors.10 The 4 surgical units had participated in the NCR outcomes studies since 1995. Their results from 1995 to 1997 as defined by Catquest are shown in Table 1. In 1998, a retrospective study was performed to identify the reasons for a no-benefit outcome from 1995 to 1997.9 These reasons are shown in Table 2. The next step was to identify which reasons for a no-benefit outcome could be improved. The largest group of patients with a no-benefit outcome had a coexisting eye disorder in the eye to be operated on as a probable reason. There is a lack of knowledge about which patients with a certain disorder, for instance macular degeneration, benefit from cataract extraction. Until greater knowledge about patients with co-existing eye disorders is achieved, a change in surgical indications cannot and should not be suggested. Another large group of patients had anisometropia as a probable reason for the poor outcome. Even if the anisometropia were deliberate (ie, waiting for surgery in the fellow eye), the presence of disturbing anisometropia 6 months after surgery must be considered poor care. It should be possible to reduce the number of patients in this group through better surgical planning. Another group of patients had a disturbing cataract in the fellow eye. It should also be possible to reduce the number of patients in this group through better surgical strategy. 972
1999 (N ⴝ 390)
The outcome was judged poor in some cases in which there were few difficulties preoperatively. This means that the instrument could not measure difficulties before surgery and therefore could not measure any improvement. This is a result of the indications for surgery and/or measurement problems,11 not necessarily poor care. Other reasons for a poor outcome included complications during and after surgery; in some cases, the reasons were unknown. Complications of surgery may, of course, be a result of poor care. Reducing the number of complications during and after surgery is a continuous goal at all surgical units, however, and was therefore not specifically included in this project. This report describes the action taken by the 4 surgical units during the 1999 study to reduce the number of patients with a no-benefit outcome after cataract surgery and gives the results achieved.
Table 2. Reasons for a no-benefit outcome. Number (%) 1995–97 Study†
1999 Study‡
Co-existing eye disease in the surgical eye
37 (48.1)
22 (57.9)
Anisometropia
21 (27.3)
4 (10.5)
Disturbances from fellow eye
10 (13.0)
4 (10.5)
Low disability score (few preoperative difficulties)
9 (11.7)
9 (23.7)
Unknown
8 (10.4)
4 (10.5)
Postoperative complication
8 (10.4)
1 (2.6)
Complication during surgery
7 (9.1)
0
Not suitable glasses
5 (6.5)
2 (5.2)
Reason*
*One patient could have more than 1 reason for the poor outcome. † In this study, 77 patients had a no-benefit outcome. ‡ In this study, 38 patients had a no-benefit outcome.
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Results
Table 3. Preoperative conditions. Number (%) 1995–97 Study (N ⴝ 770)
1999 Study (N ⴝ 390)
P Value*
Low pre-operative score sum (⬍9) (⫽few difficulties)
133 (17.3)
83 (21.3)
.097
Best vision better eye, preoperatively ⬍0.5
257 (33.4)
95 (24.4)
.002
Second-eye surgery
250 (32.5)
142 (36.4)
.180
Ocular co-morbidity in the surgical eye
299 (38.8)
157 (40.3)
.639
Variable
*Chi-square test
Patients and Methods Data on all consecutive cataract extractions performed at the 4 surgical units during March 1999 were collected and reported to the NCR according to the routines for participation in the NCR.7 This included a completed Catquest questionnaire by all patients before and 6 months after surgery. The patients scheduled for surgery during the study month were treated using the following guidelines: 1. Patients scheduled for second-eye surgery. Care should be taken to achieve isometropia. Thus, if there is no strong reason to create monovision, the target refraction in the eye to be operated on should be as close as possible to the refraction in the previously operated eye. 2. Patients scheduled for first-eye surgery. In patients with cataract in both eyes, second-eye surgery should be planned within 2 to 3 months (May or June) after first-eye surgery in March if the patient does not object. If there is no or a mild cataract in the second eye and the patient perceives no disturbances from this eye or does not want surgery, only first-eye surgery should be performed. In all patients scheduled for first-eye surgery, the problem of anisometropia should be addressed to ensure isometropia at follow-up.
Surgical outcomes data and completed preoperative and postoperative questionnaires were available for 390 patients at the participating units. During the study month, first-eye surgery was performed in 249 cases and second-eye surgery, in 141 cases. A cataract extraction in the fellow eye during the follow-up (6 months) was performed in 69 cases. Thus, outcomes data were complete for 180 patients having first-eye surgery in March without further surgery during the study period, 69 patients with second-eye surgery 2 to 3 months after surgery in the first eye (in March), and 141 patients having secondeye surgery in March 1999. A no-benefit outcome was noted in 38 cases (9.7% of all surgery). Table 1 shows the percentage of patients with a no-benefit outcome from 1995 through 1999 by surgical unit. The probable reasons for a no-benefit outcome are shown in Table 2. The reasons in 1999 were different from those in previous years, before the new strategy was launched. Anisometropia decreased as a probable reason for a poor outcome, from 27.3% in the previous study (1995 through 1997) to 10.5% in 1999 (P ⫽ .041, Pearson chi square). All patients in the 1999 study (N ⫽ 4) were among those who had first-eye sur-
Table 4. Preoperative visual acuity in the fellow eye before surgery in March. Visual Acuity
Measurement
First-Eye Surgery (n ⴝ 180)
Surgery in Both Eyes* (n ⴝ 69)
Second-Eye Surgery (n ⴝ 141)
25th percentile
0.4
0.3
0.5
Median
0.7
0.5
0.7
75th percentile
0.9
0.6
0.9
*Refers to fellow eye at first-eye surgery.
Figure 1. (Lundstro¨ m) Distribution of the difference in refraction (spherical equivalent) between the 2 eyes in a patient in the first-eye surgery, surgery in both eyes within 6 months, and second-eye surgery groups. The median difference was 0.75 D, 0.60 D, and 0.50 D, respectively, and 60%, 73.9%, and 80.9%, respectively, were within ⫾1.00 D. Within the box is the middle 50% of the values, and the white line represents the median of the distribution. The vertical lines above and below the box indicate the extent of 95% of the values.
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gery in March without further surgery. Progress of cataract in the fellow eye was judged as a probable reason in 13.0% of cases in the previous study and 10.5% in the 1999 study (P ⫽ .704, Pearson chi square). Complications during and after surgery occurred at a much lower frequency in the 1999 study. In contrast, a low disability score sum before surgery and ocular co-morbidity were cited more frequently as reasons for a no-benefit outcome in the 1999 study than in the earlier study. Table 3 shows the case-mix variables in the previous study and the 1999 study. The duration from first-eye surgery in March 1999 to surgery in the fellow eye was within 3 months in 66 of the 69 patients. The mean time between surgery in the first eye and that in the second eye was 2.0 months. Thus, the goal of 2 to 3 months between surgeries was fulfilled in most cases (95.7%). Six patients had bilateral cataract extraction on the same day. These patients are represented only by their first eye but are included in the group having surgery in both eyes during the study period. The patients selected for both first- and second-eye surgery during the study period had a worse preoperative visual acuity in the better eye than in the fellow eye in the group having first-eye surgery only (Table 4). The difference in preoperative visual acuity between eyes having bilateral surgery and those having first-eye surgery was statistically significant (P ⬍ .001, Mann-Whitney U test). In the 1999 study, the mean difference in the final refraction between the 2 eyes was 0.71 diopter (D) ⫾ 0.63 (SD) in patients having bilateral surgery, 1.15 ⫾ 1.25 D in patients having first-eye surgery, and 0.75 ⫾ 0.92 D in patients having second-eye surgery. The distribution of the difference in refraction between eyes in these 3 groups is shown in Figure 1. The difference in values between the group having surgery in 1 eye and that having surgery in both eyes was statistically significant (P ⫽ .006, t test). There was no significant difference in values between patients having second-eye surgery and those having surgery in both eyes. The outcomes as defined by Catquest in patients having first-eye surgery, surgery in both eyes, and second-eye surgery during the 1999 study are shown in Table 5. The outcome was best in patients having surgery in both eyes during the study period; however, the difference among the groups was not statistically significant. 974
Table 5. Outcomes of cataract surgery as defined by Catquest, 1999 study. Percentage Benefit Level Very good Good Moderate Questionable No benefit
First-Eye Surgery (n ⴝ 180)
Surgery in Both Eyes (n ⴝ 69)
Second-Eye Surgery (n ⴝ 141)
38.9
43.5
40.4
4.4
5.8
10.6
35.6
37.7
31.2
9.4
8.7
7.8
11.7
4.3
9.9
Table 6 shows the patients’ satisfaction with their vision 6 months after surgery. Patients having surgery in both eyes during the study period were significantly more satisfied with their vision than patients having first-eye surgery (P ⬍ .001, Mann-Whitney U test) and those having second-eye surgery (P ⫽ .006, MannWhitney U test).
Discussion The aim of this study was to decrease the number of patients perceiving more difficulties 6 months after cataract extraction than before surgery. The reduction from the previous study (1995 through 1997) was small, from 10.5% to 9.7%. Only 1 surgical department had a decrease in the number of patients with a no-benefit outcome in 1999 compared to the previous study. The strategy to achieve our goal was to reduce the number of patients reporting more difficulties after cataract extraction than before because of a disturbing cataract in the fellow eye or anisometropia. These reasons for a nobenefit outcome decreased considerably. The number of Table 6. Patient satisfaction 6 months after surgery in March, 1999 study. Percentage Degree of Satisfaction
First-Eye Surgery (n ⴝ 180)
Surgery in Both Eyes (n ⴝ 69)
Second-Eye Surgery (n ⴝ 141)
Very satisfied
33.9
68.1
51.8
Rather satisfied
40.6
23.2
34.8
Rather dissatisfied
11.1
4.3
6.4
7.2
1.4
4.3
Very dissatisfied
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patients in whom postoperative anisometropia was a probable reason for a no-benefit outcome was significantly lower. By chance, complications during and after surgery as a probable reason for a no-benefit outcome also decreased in frequency. However, other reasons for a worse outcome (eg, ocular co-morbidity, a low preoperative disability score) increased in frequency, resulting in an overall small decrease in no-benefit outcomes. Thus, the case mix was different in the 1999 study than in the previous study. More patients in the 1999 study had an ocular co-morbidity in the eye to be operated on than in the previous study. Ocular co-morbidity in the surgical eye has been correlated with a worse outcome.12,13 Furthermore, patients in the 1999 study had fewer preoperative difficulties than patients in the previous study. Fewer difficulties before surgery result in a low disability score sum, making it harder to measure improvement after surgery.11 The most obvious difference in preoperative conditions, however, was significantly better visual acuity in the better eye in the 1999 study than in the previous study. The measures taken to achieve a low number of no-benefit results were in accordance with the plan. Surgery in the second eye was performed in most cases within 3 months after first-eye surgery. This gave a recovery time of at least 3 months after the last surgery before the patients completed the Catquest questionnaire. In the other 2 groups of patients, the follow-up between surgery and Catquest was 6 months. This difference may have also influenced the results. An important finding in our study was the higher satisfaction with vision of patients who had surgery in both eyes during the study period than of patients who had surgery in 1 eye only. This finding supports the concept of performing second-eye surgery without too much delay in patients with bilateral cataract. The patients selected for surgery in the fellow eye during the follow-up had a significantly worse visual acuity in this eye before first-eye surgery. This indicates that surgery in both eyes within a short interval was performed mainly in patients with cataract and poor vision in both eyes. This finding may also partly explain the low number of patients in this group having a nobenefit outcome. The difference in refraction between the 2 eyes in a patient after surgery was reasonably low. First-eye sur-
gery resulted in the largest difference, which is understandable. In patients having surgery in both eyes, there was also a difference in refraction between the eyes. The lowest median value (0.5 D) and smallest spread of values were in patients having second-eye surgery in March. Patients having surgery in both eyes and those having second-eye surgery had mean values (0.71 D and 0.75 D, respectively) within the limit of what has been reported as a difference between target refraction and final refraction in clinical practice.14
Conclusion A strategy to reduce the number of patients perceiving more visual disability after cataract surgery than before was tested. The number of patients with the targeted reasons for a poor outcome who perceived no benefit decreased considerably. However, patients with other reasons for a poor outcome increased in frequency, with the main reason presumably being changes in the case mix.
References 1. 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 2. Cataract Management Guideline Panel. Cataract in Adults. Management of Functional Impairment. Rockville, MD, U.S. Department of Health and Human Services, Public Health Service, Agency for Health Care Policy and Research, 1993 (AHCPR pub #93– 0542; clinical practice guideline #4) 3. Sloan 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 Series. Washington, DC, Optical Society of America, 1992; 1:26 –29 4. Steinberg EP, Tielsch JM, Schein OD, et al. The VF-14; an index of functional impairment in patients with cataract. Arch Ophthalmol 1994; 112:630 – 638 5. Lundstro¨ m M, Roos P, Jensen S, Fregell G. Catquest questionnaire for use in cataract surgery care: description, validity, and reliability. J Cataract Refract Surg 1997; 23:1226 –1236 6. Lundstro¨ m M, Stenevi U, Thorburn W, Roos P. Catquest questionnaire for use in cataract surgery care: assessment of surgical outcomes. J Cataract Refract Surg 1998; 24:968 –974
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7. Lundstro¨ m M, Stenevi U, Thorburn W. Cataract surgery in the very elderly. J Cataract Refract Surg 2000; 26: 408 – 414 8. Nolan TW, Provost LP. Understanding variation. Quality Progress 1990; May:70 –78 9. Lundstro¨ m M, Brege KG, Flore´n I, et al. Impaired visual function after cataract surgery assessed using the Catquest questionnaire. J Cataract Refract Surg 2000; 26:101–108 10. Batalden PB, Nelson EC, Roberts JS. Linking outcomes measurement to continual improvement: the serial “V” way of thinking about improving clinical care. Jt Comm J Qual Improv 1994; 20:167–180 11. Mangione CM, Orav EJ, Lawrence MG, et al. Prediction of visual function after cataract surgery; a prospectively validated model. Arch Ophthalmol 1995; 113:1305–1311 12. Willerscheidt AB, Healey ML, Ireland M. Cataract surgery outcomes: importance of co-morbidities in case mix. J Cataract Refract Surg 1995; 21:177–181
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13. Lundstro¨ m M, Stenevi U, Thorburn W. Outcome of cataract surgery considering the preoperative situation: a study of possible predictors of the functional outcome. Br J Ophthalmol 1999; 83:1272–1276 14. Lundstro¨ m M, Barry P, Leite E, et al. 1998 European Cataract Outcome Study; report from the European Cataract Outcome Study Group. J Cataract Refract Surg 2001; 27:1176 –1183
From the Departments of Ophthalmology, Blekinge Hospital, Karlskrona (Lundstro¨m), Ma¨ larsjukhuset, Eskilstuna (Brege), Lund University Hospital, Lund (Flore´n), and Sahlgren’s Hospital, Mo¨lndal (Stenevi), and Umeå University Hospital, Umeå (Thorburn), Sweden. Supported by grants from the National Board of Health and Welfare in Sweden and the Federation of County Councils. Karin Johansson provided the numerical information from the database.
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