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The effect of low-vision simulators on ophthalmology residents' perception of quality of life
The effect of low-vision simulators on ophthalmology residents’ perception of quality of life Chiun-Ho Hou,*† MD; Ken-Kuo Lin,*‡ MD; Chee-Jen Chang,† PhD; Jiahn-Shing Lee,*‡ MD, PhD !"342!#4 s 2»35-» Objective: To evaluate the effect of low-vision simulators on daily activities performed by ophthalmology residents. Design: Experimental study. Participants: Twenty-nine ophthalmology residents. -ETHODS Four types of low-vision simulators—central loss, peripheral loss, hemianopia, and overall blur—were provided to 29 residents. They wore these simulators while performing daily activities described in the Visual Function-14 (VF-14). Their VF-14 scores after the exercises and the utility values before and after the exercises were analyzed. Results: After the exercises, the residents recorded significantly different utility values in the peripheral loss and overall blur groups. The changes in utility values were similar for the senior and junior residents. On the basis of the mean VF-14 scores of the 4 simulators, the residents considered overall blur to be the most serious visual impairment and hemianopia to be the least. #ONCLUSION Ophthalmology residents tend to underestimate the impact of visual disability on patients’ quality of life. They can gain a better appreciation of such an impact by using low-vision simulators during daily activities. Objet : Évaluation de l’effet des simulateurs de basse vision sur les activités quotidiennes des résidents en ophtalmologie. Nature : Étude expérimentale. Participants : Vingt-neuf résidents en ophtalmologie. -£THODES : Quatre types de simulateurs de basse vision—perte centrale, perte périphérique, hémianopsie et vue embrouillée—ont été présentés aux 29 résidents. Ils ont porté ces simulateurs dans l’exercice de leurs activités quotidiennes comme le décrit la Fonction visuelle-14. Les résultats VF-14 après les exercices et les valeurs utilitaires avant et après les exercices ont été analysés. 2£SULTATS : Après les exercices, les résidents ont noté des valeurs utilitaires significativement différentes quant à la perte périphérique et à la vue embrouillée. Les changement de valeurs utilitaires étaient semblables entre les résidents juniors et séniors. Selon la moyenne des notes VF-14 des 4 simulateurs, les résidents ont considéré la vue embrouillée comme étant la déficience visuelle la plus sérieuse et l’hémianopise la moins grave. #ONCLUSION : Les résidents en ophtalmologie ont tendance à sousestimer l’impact de la déficience visuelle sur la qualité de vie des patients. Ils peuvent obtenir une meilleure appréciation d’un tel impact en utilisant les simulateurs de basse vision dans leurs activités quotidiennes.
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tudies have shown a disparity between how patients and how physicians perceive the impact of disability on quality of life, in ophthalmology and in other medical fields.1–4 Visual impairment is a common cause of functional disability, especially in the elderly. To aid in the rehabilitation of patients, various low-vision simulators have been suggested for their caretakers, so that they can experience the impact of visual disability. However, the effects of these simulators have never been submitted to rigorous evaluation. In this study, we used utility values to analyze changes to our residents’ perceptions of quality of life before and after wearing low-vision simulators while performing the daily activities as described in the Visual Function-14 (VF-14), a questionnaire for evaluating vision-related quality of life.5 From *the Department of Ophthalmology, Chang Gung Memorial Hospital, Taipei, and the †Graduate Institute of Clinical Medical Science, ‡ College of Medicine, Chang Gung University, Taoyuan, Taiwan Originally received Dec. 19, 2008. Revised July 27, 2009 Accepted for publication Aug. 10, 2009 Published online Oct. 29, 2009
METHODS
Four types of low-vision simulators (VisualEyes Simulators, Lighthouse, N.Y.), central loss, peripheral loss, hemianopia, and overall blur, were provided to residents between April 2006 and July 2008. These simulators are goggles that approximate these 4 common types of visual impairment. The central loss simulator mimics macular degeneration by limiting central vision to about 6/20 and sparing peripheral vision. The peripheral loss simulator approximates glaucoma by constricting visual field to 10–15q without affecting visual acuity. The hemianopia simulator mimics left brain lesion by obscuring the right half of the visual field. Finally, the overall blur simulator mimics Correspondence to Jiahn-Shing Lee, MD, Department of Ophthalmology, Chang Gung Memorial Hospital. 5 Fu-Shing St., Guei-Shan Shiang, Tao-Yuan, Taiwan, 333, R.O.C.; [email protected]; and Chee-Jen Chang, PhD, Graduate Institute of Clinical Medical Science, College of Medicine, Chang Gung University. 259 Wen-Hwa 1st Rd., Kwei-Shan Shiang, Tao-Yuan, Taiwan, 333, R.O.C.; [email protected] This article has been peer-reviewed. Cet article a été évalué par les pairs. Can J Ophthalmol 2009;44:692–6 doi:10.3129/i09-192
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Low-vision simulators and quality of life—Hou et al. cataract by reducing visual acuity to approximately 6/30. Before the experiments, the residents were asked to read descriptions of the simulators’ properties. At the same time we explained the study procedures and allowed them to acclimatize to the 4 simulators for about 10 minutes while sitting still and not performing any activities. Their perceptions of quality of life while wearing each of the simulators were immediately assessed by utility values, including the time trade-off and standard gamble methods.6,7 According to the principle of utilities, higher utility values are correlated with better quality of life. The utility value of 1.0 refers to perfect health and no functional difficulty. On the other end of the scale, the utility value of 0.0 refers to death. In the time trade-off method, the residents were asked how many additional years they expected to live. Then they were asked how many years of their life they would give up in return for full recovery from the impairment they were experiencing. The utility value was calculated by subtracting from 1.0 the number of years they would give up divided by the number of years they expected to live. In the standard gamble method, the residents were presented with a scenario in which treatment for the impairment was available. If successful, the treatment could totally and perfectly recover their vision. However, if it failed, the price was death. We then asked them how great a risk they were willing to take before refusing the treatment. The utility value was calculated by subtracting from 1.0 the percentage of risk that they were willing to take. A utility value of double blindness, no light perception in both eyes, was also asked as a reference. After completing the procedures described, all of the residents wore each of the 4 simulators, in turn, while performing the daily activities described in the VF-14 for a period of 1 week. The VF-14 was done after the wearing of the simulators. The residents were asked to complete at least 1 task of each item of the VF-14 with 1 simulator at a time, and then to score their level of difficulty with this task. The order of the simulators and the tasks was randomized among the residents. After performing all of the 14 daily activities, the residents were asked to value the utilities again for each simulator. There are 14 items in VF-14: (i) reading small print, such as on the labels on medicine bottles or in a telephone book; (ii) reading a newspaper or a book; (iii) reading a large-print book or large-print newspaper or numbers on a telephone; (iv) recognizing people when they are close to you; (v) noticing steps, stairs or curbs; (vi) reading traffic, street or store signs; (vii) doing fine handwork such as sewing, knitting, crocheting, or carpentry; (viii) writing cheques or filling out forms; (ix) playing games such as bingo, dominoes, card games, or mahjong; (x) taking part in sports such as bowling, handball, tennis, or golf; (xi) cooking; (xii) watching television; (xiii) daytime driving; and (xiv) nighttime driving. For item (i), the residents were asked to read the name and usage on 1 medicine bottle. For items (ii) and (iii), they were asked to read the headline and a story in a newspaper.
For items (iv), (v), and (vi), they were asked, at a minimum, to recognize 1 face, climb up or down 1 floor, and read 1 sign. For item (vii), they were asked to sew the button onto a piece of cloth. For item (viii), they were asked to fill out 1 form for money deposit or withdrawal. For item (xi), they were asked to cook a dish. For items (ix), (x), (xii), (xiii), and (xiv), they were asked to participate for at least 10 minutes. Scores of 4, 3, 2, 1, or 0 referred to “no difficulty,” “a little difficulty,” “a moderate amount of difficulty,” “a great deal of difficulty,” and “unable to do,” respectively, for each of the 14 activities. Any activity that the resident had never performed was not included in the scoring. Scores on all included items were averaged and then multiplied by 25 to yield a final score from 100 to 0, with 100 indicating that the patient could perform all applicable activities without difficulty and 0 meaning that the patient was unable to perform any applicable activities. Since safety was a concern during driving, the residents were asked only to sit next to the driver and try to get a sense of the difficulty. The statistical analysis was performed by student’s t test and ANOVA. The post-hoc analysis for ANOVA was done by Scheffe’s test. A p value of less than 0.05 was considered statistically significant. RESULTS
Twenty-nine ophthalmology residents at Chang Gung Memorial Hospital (Taipei), ranging from their first year to their fifth year of residency, were invited to participate in this study. The residents included 10 men and 19 women. Their mean age was 30.1 (SD = 3.17) years, ranging from 26 to 40 years. In the time trade-off method, the residents’ expected life was 44.75 years on average, ranging from 30 to 65 (SD = 9.44), and their mean utility value of double blindness was 0.44, ranging from 0 to 0.846 (SD = 0.25). In the standard gamble method, the mean utility value of double blindness was 0.56, ranging from 0 to 0.95 (SD = 0.30). Before the exercises, the mean utility value was not significantly different in the 4 visual impairment groups (p = 0.151 in the time trade-off method and p = 0.782 in the standard gamble method by ANOVA) (Table 1). After the exercises, the mean utility values in the 4 groups were significantly different in the time trade-off method (p = 0.001 by ANOVA) but not in the standard gamble method (p = 0.171 by ANOVA). Before and after the exercises, the residents’ mean utility values changed significantly in the peripheral loss and overall blur groups (p = 0.027 and 0.0009, respectively, in the time trade-off method, and p = 0.031 and 0.001 in the standard gamble method, by paired t test). Their results, however, did not change significantly in the other 2 groups: central loss and hemianopia. We compared the residents’ mean VF-14 scores for the 4 simulators (Table 2). The scores were significantly different in the 4 groups (p < 0.0001 by ANOVA). The Scheffe’s posthoc test showed that the overall blur group had the lowest CAN J OPHTHALMOL—VOL. 44, NO. 6, 2009
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Low-vision simulators and quality of life—Hou et al. in 2006 revealed a 17% rate of visual impairment in adults 65 years and older.8 After arthritis and heart disease, this is the third most common cause of functional disability in people older than 70.9 It has therefore been proposed that low-vision education be included in ophthalmology residents’ training, to provide future ophthalmologists with a stronger awareness and thus provide better care for these patients.10 Exercises with low-vision simulators are occasionally included in such programs to let the residents perceive the impact of visual disability. However, these exercises are usually performed with very few daily activities, and their educational value has seldom been assessed. In this study, we asked our residents to use the simulators while performing the daily activities listed in the VF-14, whose usefulness and validity have been demonstrated in patients with cataract, glaucoma, and corneal and retinal diseases.11–13 We therefore decided to use all 14 of the items to cover the important aspects of daily life with which lowvision patients might experience difficulty. To analyze the effects of the exercises, we chose another validated instrument—utility value—to measure our residents’ perception of the impact of a particular disease state according to their experience with the simulators. We found that our residents’ VF-14 scores tended to be lower than those of real patients, as reported in previous
score, with p values all <0.0001 with respect to the other 3 groups. This indicated that the residents felt that overall blur affected the daily activities most seriously. This was followed by peripheral loss and central loss (these 2 groups had a p value of 0.56 in comparison). The hemianopia group had the highest score (all p < 0.0001 in comparison). We further divided the residents into 2 groups according to their year of residency. The senior group comprised those in their fourth and fifth year of residency; the junior group included the younger residents. The senior group consisted of 13 residents with a mean age of 31.3 (SD = 2.81) years and a range of 29–40 years. The junior group comprised 16 residents with a mean age of 29.1 (SD = 3.20) years and a range of 26–37 years. There was no significant age difference (p = 0.064 in unpaired t test). We compared the changes in the residents’ utility values in the 4 kinds of visual impairment after the exercises had been completed (Table 3). We found no significant difference with either the time trade-off or the standard gamble methods after the exercises (all p values >0.05 by unpaired t test). DISCUSSION
Low vision is a common problem, especially in the elderly. A National Health Interview Survey in the United States
Table 1—Residents’ mean utility values before and after VF-14 exercises, in both time trade-off and standard gamble methods Time trade-off method
Standard gamble method
Group
Before (SD)
After (SD)
p*
Before (SD)
After (SD)
p*
Central loss Peripheral loss Hemianopia Overall blur ANOVA†
0.80 (0.12) 0.74 (0.16) 0.83 (0.11) 0.78 (0.16) 0.151
0.78 (0.14) 0.69 (0.16) 0.82 (0.12) 0.68 (0.19) 0.001
0.388 0.027 0.600 0.0009
0.83 (0.18) 0.80 (0.21) 0.85 (0.18) 0.80 (0.23) 0.782
0.83 (0.17) 0.77 (0.20) 0.82 (0.21) 0.71 (0.25) 0.171
0.669 0.031 0.121 0.001
*p value of paired t test. † p value of ANOVA test. Note: VF-14, Visual Function-14.
Table 2—Residents’ mean VF-14 scores for the 4 simulator groups and results of ANOVA and post-hoc analysis Group Central loss Peripheral loss Hemianopia Overall blur ANOVA*
Score (SD)
Order in score
Comparison
p value
48.98 (13.39) 43.58 (13.18) 67.84 (17.55) 24.33 (12.99)
2 2 1 3
Peripheral loss/central loss Hemianopia/central loss Hemianopia/peripheral loss Overall blur/central loss Overall blur/peripheral loss Overall blur/hemianopia
0.56 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001
<0.0001
*p value <0.0001 by ANOVA among the 4 groups; the post-hoc comparison was done by Scheffe’s test. Note: VF-14, Visual Function-14.
Table 3—Comparison of junior and senior residents’* mean change in utility values after VF-14 exercises using both the time trade-off and the standard gamble methods Time trade-off method Group Central loss Peripheral loss Hemianopia Overall blur
Standard gamble method
Junior (SD)
Senior (SD)
p†
Junior (SD)
Senior (SD)
p†
–0.007 (0.078) –0.064 (0.091) –0.021 (0.098) –0.129 (0.132)
–0.03 (0.134) –0.032 (0.139) –0.001 (0.120) –0.072 (0.169)
0.577 0.458 0.589 0.317
0.003 (0.081) –0.037 (0.067) –0.049 (0.114) –0.096 (0.164)
–0.018 (0.071) –0.023 (0.082) –0.007 (0.079) –0.084 (0.094)
0.477 0.621 0.275 0.811
*Junior residents group, first to third year of residency; senior residents, fourth and fifth year of residency. † p value of unpaired t test. Note: VF-14, Visual Function-14.
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Low-vision simulators and quality of life—Hou et al. studies. For example, our residents’ mean VF-14 score in the central loss group was only 49, whereas that in a group of patients with age-related macular degeneration and a mean visual acuity (VA) of 6/20 in the better eye was reported as 62.14 Our residents’ mean VF-14 score in the peripheral loss group was 44, whereas that in a group of glaucomatous patients with a similar AGIS (Advanced Glaucoma Intervention Study) score was in the 60–70 range.15 Our residents’ mean VF-14 score in the overall blur group was 24, and that in a group of patients with cataract with a VA between 6/15 and 6/60 was about 70.5,16 In contrast, the utility values both before and after our residents had performed the daily activities tended to be higher than those of real patients. For example, the utility value for the group of age-related macular degeneration patients, with VA from 6/18 to 6/30, was reported to be 0.57 by the time trade-off method and 0.69 by the standard gamble method.1 The utility value for the group of glaucomatous patients, with a similar median deviation of visual field loss, was 0.64 by the time trade-off method.13 However, the utility value for the group of cataract patients with VA of 6/15 or worse was 0.78 by the time trade-off method and 0.84 by the standard gamble method, similar to our residents’ utility values before the exercises but higher than those of the residents after the exercises.16 The VF-14 score was higher in real patients than in our residents, which is probably related to some degree of adaptation in the patients performing daily activities. The patients in the reports cited above had suffered from visual impairments for a considerable amount of time and had probably developed skills to help them cope with their impairments. This was not the case with our residents, who wore simulators for only a week to complete this study. The higher utility values reported by our residents suggested that, even after the exercises, there was still some disparity between them and the patients with respect to their perceptions of quality of life due to visual impairment. Nevertheless, the disparity decreased after the exercises in both the peripheral loss and the overall blur groups, though not in the other 2 groups. This was probably due to the relatively poor design of the latter 2 simulators. When wearing either the central loss or the hemianopia simulator, the residents could easily avoid the obscured area by unintentionally tilting their head or moving their eye to regain their normal vision. This decreased the disabling effect of the simulators and influenced our residents’ perception of the impairment. Unlike the other 3 types of visual impairment, cataract-related vision loss is now curable. Therefore, the utility value for cataract patients is higher than that for our residents wearing an overall blur simulator. The difference between the 4 simulators was statistically significant when measuring the residents’ mean VF-14 scores and their utilities obtained with the time trade-off method, but not those obtained with the standard gamble method. This was probably due to a difference in the residents’ choice for the desirability of life from perfect health
to death among these 3 methods of measurement. The level of difficulty in both VF-14 and the time trade-off method was scored by a multiple or grading choice, whereas that in the standard gamble method was scored by an all-or-none choice. Given most people’s fear of sudden death, the differences between the simulators in the standard gamble method was less remarkable, and its score was always higher than that with the time trade-off method.17 The results did not differ greatly between junior and senior residents in our study, suggesting that medical knowledge helps very little in appreciating the inconvenience experienced by disabled patients. This observation is supported by a previous report in which clinicians and community members had a similar utility value for age-related macular degeneration, but this was higher than that of the patients.2 Therefore, it is crucial to include both medical knowledge and other training, such as these exercises with low-vision simulators, in low-vision education provided to residents. In summary, our study demonstrates that ophthalmology residents tend to underestimate the impact of functional disability in visually impaired patients. Although the lowvision simulator exercises cannot provide a true experience of visual impairment, they help the residents to better appreciate the inconvenience of these disabilities. We suggest that medical knowledge and appropriate low-vision simulator exercises while performing daily activities are both important in residents’ training. The authors have no proprietary or commercial interest in any materials discussed in this article.
REFERENCES 1. Brown GC, Brown MM, Sharma S. Difference between ophthalmologists’ and patients’ perceptions of quality of life associated with age-related macular degeneration. Can J Ophthalmol 2000;35:127–33. 2. Stein JD, Brown MM, Brown GC, Hollands H, Sharma S. Quality of life with macular degeneration: perceptions of patients, clinicians and community members. Br J Ophthalmol 2003;87:8–12. 3. Schrader GD. Subjective and objective assessments of medical comorbidity in chronic depression. Psychother Psychosom 1997; 66:258–60. 4. Rothwell PM, McDowell Z, Wong CK, Dorman PJ. Doctors and patients don’t agree. Cross sectional study of patients’ and doctors’ perceptions and assessments of disability in multiple sclerosis. BMJ 1997;314:1580–3. 5. Steinberg EP, Tielsch JM, Schein OD, et al. The VF-14: an index of functional impairment in cataract patients. Arch Ophthalmol 1994;112:630–8. 6. Brown GC. Vision and quality-of-life. Trans Am Ophthalmol Soc 1999;92:473–511. 7. Brown MM, Brown GC, Sharma S, Garrett S. Evidence-based medicine, utilities and quality of life. Curr Opin Ophthalmol 1999;10:221–6. 8. Pleis JR, Lethbridge-Çejku M. Summary health statistics for CAN J OPHTHALMOL—VOL. 44, NO. 6, 2009
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9.
10. 11.
12.
13.
U.S. adults: National Health Interview Survey, 2006. National Center for Health Statistics. Vital Health Stat 2007;10:1–153. Swagerty DL Jr. The impact of age-related visual impairment on functional independence in the elderly. Kans Med 1995;96:24–6. Torrance GW, Feeny D. Utilities and quality-adjusted life years. Int J Technol Assess Health Care 1989;2:559–75. Musch DC, Farjo AA, Meyer RF, Waldo MN, Janz NK. Assessment of health-related quality of life after corneal transplantation. Am J Ophthalmol 1997;124:1–8. Linder M, Chang TS, Scott IU, et al. Validity of the visual function index (VF-14) in patients with retinal disease. Arch Ophthalmol 1999;117:1611–6. Gupta V, Srinivasan G, Mei SS, Gazzard G, Sihota R, Kapoor KS. Utility values among glaucoma patients: an impact on the quality of life. Br J Ophthalmol 2005;89:1241–4.
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14. Riusala A, Sarna S, Immonen I. Visual function index (VF-14) in exudative age-related macular degeneration of long duration. Am J Ophthalmol 2003;135:206–12. 15. Gutierrez P, Wilson MR, Johnson C, et al. Influence of glaucomatous visual field loss on health-related quality of life. Arch Ophthalmol 1997;115:777–84. 16. Saw SM, Gazzard G, Gomezperalta C, Au Eong KG, Seah S. Utility assessment among cataract surgery patients. J Cataract Refract Surg 2005;31:785–91. 17. Wakker P, Stiggelbout A. Explaining distortions in utility elicitation through the rank-dependent model for risky choices. Med Decis Making 1995;15:180–6.
Keywords: low vision, education, assessment
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tudies have shown a disparity between how patients and how physicians perceive the impact of disability on quality of life, in ophthalmology and in other medical fields.1–4 Visual impairment is a common cause of functional disability, especially in the elderly. To aid in the rehabilitation of patients, various low-vision simulators have been suggested for their caretakers, so that they can experience the impact of visual disability. However, the effects of these simulators have never been submitted to rigorous evaluation. In this study, we used utility values to analyze changes to our residents’ perceptions of quality of life before and after wearing low-vision simulators while performing the daily activities as described in the Visual Function-14 (VF-14), a questionnaire for evaluating vision-related quality of life.5 From *the Department of Ophthalmology, Chang Gung Memorial Hospital, Taipei, and the †Graduate Institute of Clinical Medical Science, ‡ College of Medicine, Chang Gung University, Taoyuan, Taiwan Originally received Dec. 19, 2008. Revised July 27, 2009 Accepted for publication Aug. 10, 2009 Published online Oct. 29, 2009
METHODS
Four types of low-vision simulators (VisualEyes Simulators, Lighthouse, N.Y.), central loss, peripheral loss, hemianopia, and overall blur, were provided to residents between April 2006 and July 2008. These simulators are goggles that approximate these 4 common types of visual impairment. The central loss simulator mimics macular degeneration by limiting central vision to about 6/20 and sparing peripheral vision. The peripheral loss simulator approximates glaucoma by constricting visual field to 10–15q without affecting visual acuity. The hemianopia simulator mimics left brain lesion by obscuring the right half of the visual field. Finally, the overall blur simulator mimics Correspondence to Jiahn-Shing Lee, MD, Department of Ophthalmology, Chang Gung Memorial Hospital. 5 Fu-Shing St., Guei-Shan Shiang, Tao-Yuan, Taiwan, 333, R.O.C.; [email protected]; and Chee-Jen Chang, PhD, Graduate Institute of Clinical Medical Science, College of Medicine, Chang Gung University. 259 Wen-Hwa 1st Rd., Kwei-Shan Shiang, Tao-Yuan, Taiwan, 333, R.O.C.; [email protected] This article has been peer-reviewed. Cet article a été évalué par les pairs. Can J Ophthalmol 2009;44:692–6 doi:10.3129/i09-192
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Low-vision simulators and quality of life—Hou et al. cataract by reducing visual acuity to approximately 6/30. Before the experiments, the residents were asked to read descriptions of the simulators’ properties. At the same time we explained the study procedures and allowed them to acclimatize to the 4 simulators for about 10 minutes while sitting still and not performing any activities. Their perceptions of quality of life while wearing each of the simulators were immediately assessed by utility values, including the time trade-off and standard gamble methods.6,7 According to the principle of utilities, higher utility values are correlated with better quality of life. The utility value of 1.0 refers to perfect health and no functional difficulty. On the other end of the scale, the utility value of 0.0 refers to death. In the time trade-off method, the residents were asked how many additional years they expected to live. Then they were asked how many years of their life they would give up in return for full recovery from the impairment they were experiencing. The utility value was calculated by subtracting from 1.0 the number of years they would give up divided by the number of years they expected to live. In the standard gamble method, the residents were presented with a scenario in which treatment for the impairment was available. If successful, the treatment could totally and perfectly recover their vision. However, if it failed, the price was death. We then asked them how great a risk they were willing to take before refusing the treatment. The utility value was calculated by subtracting from 1.0 the percentage of risk that they were willing to take. A utility value of double blindness, no light perception in both eyes, was also asked as a reference. After completing the procedures described, all of the residents wore each of the 4 simulators, in turn, while performing the daily activities described in the VF-14 for a period of 1 week. The VF-14 was done after the wearing of the simulators. The residents were asked to complete at least 1 task of each item of the VF-14 with 1 simulator at a time, and then to score their level of difficulty with this task. The order of the simulators and the tasks was randomized among the residents. After performing all of the 14 daily activities, the residents were asked to value the utilities again for each simulator. There are 14 items in VF-14: (i) reading small print, such as on the labels on medicine bottles or in a telephone book; (ii) reading a newspaper or a book; (iii) reading a large-print book or large-print newspaper or numbers on a telephone; (iv) recognizing people when they are close to you; (v) noticing steps, stairs or curbs; (vi) reading traffic, street or store signs; (vii) doing fine handwork such as sewing, knitting, crocheting, or carpentry; (viii) writing cheques or filling out forms; (ix) playing games such as bingo, dominoes, card games, or mahjong; (x) taking part in sports such as bowling, handball, tennis, or golf; (xi) cooking; (xii) watching television; (xiii) daytime driving; and (xiv) nighttime driving. For item (i), the residents were asked to read the name and usage on 1 medicine bottle. For items (ii) and (iii), they were asked to read the headline and a story in a newspaper.
For items (iv), (v), and (vi), they were asked, at a minimum, to recognize 1 face, climb up or down 1 floor, and read 1 sign. For item (vii), they were asked to sew the button onto a piece of cloth. For item (viii), they were asked to fill out 1 form for money deposit or withdrawal. For item (xi), they were asked to cook a dish. For items (ix), (x), (xii), (xiii), and (xiv), they were asked to participate for at least 10 minutes. Scores of 4, 3, 2, 1, or 0 referred to “no difficulty,” “a little difficulty,” “a moderate amount of difficulty,” “a great deal of difficulty,” and “unable to do,” respectively, for each of the 14 activities. Any activity that the resident had never performed was not included in the scoring. Scores on all included items were averaged and then multiplied by 25 to yield a final score from 100 to 0, with 100 indicating that the patient could perform all applicable activities without difficulty and 0 meaning that the patient was unable to perform any applicable activities. Since safety was a concern during driving, the residents were asked only to sit next to the driver and try to get a sense of the difficulty. The statistical analysis was performed by student’s t test and ANOVA. The post-hoc analysis for ANOVA was done by Scheffe’s test. A p value of less than 0.05 was considered statistically significant. RESULTS
Twenty-nine ophthalmology residents at Chang Gung Memorial Hospital (Taipei), ranging from their first year to their fifth year of residency, were invited to participate in this study. The residents included 10 men and 19 women. Their mean age was 30.1 (SD = 3.17) years, ranging from 26 to 40 years. In the time trade-off method, the residents’ expected life was 44.75 years on average, ranging from 30 to 65 (SD = 9.44), and their mean utility value of double blindness was 0.44, ranging from 0 to 0.846 (SD = 0.25). In the standard gamble method, the mean utility value of double blindness was 0.56, ranging from 0 to 0.95 (SD = 0.30). Before the exercises, the mean utility value was not significantly different in the 4 visual impairment groups (p = 0.151 in the time trade-off method and p = 0.782 in the standard gamble method by ANOVA) (Table 1). After the exercises, the mean utility values in the 4 groups were significantly different in the time trade-off method (p = 0.001 by ANOVA) but not in the standard gamble method (p = 0.171 by ANOVA). Before and after the exercises, the residents’ mean utility values changed significantly in the peripheral loss and overall blur groups (p = 0.027 and 0.0009, respectively, in the time trade-off method, and p = 0.031 and 0.001 in the standard gamble method, by paired t test). Their results, however, did not change significantly in the other 2 groups: central loss and hemianopia. We compared the residents’ mean VF-14 scores for the 4 simulators (Table 2). The scores were significantly different in the 4 groups (p < 0.0001 by ANOVA). The Scheffe’s posthoc test showed that the overall blur group had the lowest CAN J OPHTHALMOL—VOL. 44, NO. 6, 2009
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Low-vision simulators and quality of life—Hou et al. in 2006 revealed a 17% rate of visual impairment in adults 65 years and older.8 After arthritis and heart disease, this is the third most common cause of functional disability in people older than 70.9 It has therefore been proposed that low-vision education be included in ophthalmology residents’ training, to provide future ophthalmologists with a stronger awareness and thus provide better care for these patients.10 Exercises with low-vision simulators are occasionally included in such programs to let the residents perceive the impact of visual disability. However, these exercises are usually performed with very few daily activities, and their educational value has seldom been assessed. In this study, we asked our residents to use the simulators while performing the daily activities listed in the VF-14, whose usefulness and validity have been demonstrated in patients with cataract, glaucoma, and corneal and retinal diseases.11–13 We therefore decided to use all 14 of the items to cover the important aspects of daily life with which lowvision patients might experience difficulty. To analyze the effects of the exercises, we chose another validated instrument—utility value—to measure our residents’ perception of the impact of a particular disease state according to their experience with the simulators. We found that our residents’ VF-14 scores tended to be lower than those of real patients, as reported in previous
score, with p values all <0.0001 with respect to the other 3 groups. This indicated that the residents felt that overall blur affected the daily activities most seriously. This was followed by peripheral loss and central loss (these 2 groups had a p value of 0.56 in comparison). The hemianopia group had the highest score (all p < 0.0001 in comparison). We further divided the residents into 2 groups according to their year of residency. The senior group comprised those in their fourth and fifth year of residency; the junior group included the younger residents. The senior group consisted of 13 residents with a mean age of 31.3 (SD = 2.81) years and a range of 29–40 years. The junior group comprised 16 residents with a mean age of 29.1 (SD = 3.20) years and a range of 26–37 years. There was no significant age difference (p = 0.064 in unpaired t test). We compared the changes in the residents’ utility values in the 4 kinds of visual impairment after the exercises had been completed (Table 3). We found no significant difference with either the time trade-off or the standard gamble methods after the exercises (all p values >0.05 by unpaired t test). DISCUSSION
Low vision is a common problem, especially in the elderly. A National Health Interview Survey in the United States
Table 1—Residents’ mean utility values before and after VF-14 exercises, in both time trade-off and standard gamble methods Time trade-off method
Standard gamble method
Group
Before (SD)
After (SD)
p*
Before (SD)
After (SD)
p*
Central loss Peripheral loss Hemianopia Overall blur ANOVA†
0.80 (0.12) 0.74 (0.16) 0.83 (0.11) 0.78 (0.16) 0.151
0.78 (0.14) 0.69 (0.16) 0.82 (0.12) 0.68 (0.19) 0.001
0.388 0.027 0.600 0.0009
0.83 (0.18) 0.80 (0.21) 0.85 (0.18) 0.80 (0.23) 0.782
0.83 (0.17) 0.77 (0.20) 0.82 (0.21) 0.71 (0.25) 0.171
0.669 0.031 0.121 0.001
*p value of paired t test. † p value of ANOVA test. Note: VF-14, Visual Function-14.
Table 2—Residents’ mean VF-14 scores for the 4 simulator groups and results of ANOVA and post-hoc analysis Group Central loss Peripheral loss Hemianopia Overall blur ANOVA*
Score (SD)
Order in score
Comparison
p value
48.98 (13.39) 43.58 (13.18) 67.84 (17.55) 24.33 (12.99)
2 2 1 3
Peripheral loss/central loss Hemianopia/central loss Hemianopia/peripheral loss Overall blur/central loss Overall blur/peripheral loss Overall blur/hemianopia
0.56 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001
<0.0001
*p value <0.0001 by ANOVA among the 4 groups; the post-hoc comparison was done by Scheffe’s test. Note: VF-14, Visual Function-14.
Table 3—Comparison of junior and senior residents’* mean change in utility values after VF-14 exercises using both the time trade-off and the standard gamble methods Time trade-off method Group Central loss Peripheral loss Hemianopia Overall blur
Standard gamble method
Junior (SD)
Senior (SD)
p†
Junior (SD)
Senior (SD)
p†
–0.007 (0.078) –0.064 (0.091) –0.021 (0.098) –0.129 (0.132)
–0.03 (0.134) –0.032 (0.139) –0.001 (0.120) –0.072 (0.169)
0.577 0.458 0.589 0.317
0.003 (0.081) –0.037 (0.067) –0.049 (0.114) –0.096 (0.164)
–0.018 (0.071) –0.023 (0.082) –0.007 (0.079) –0.084 (0.094)
0.477 0.621 0.275 0.811
*Junior residents group, first to third year of residency; senior residents, fourth and fifth year of residency. † p value of unpaired t test. Note: VF-14, Visual Function-14.
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Low-vision simulators and quality of life—Hou et al. studies. For example, our residents’ mean VF-14 score in the central loss group was only 49, whereas that in a group of patients with age-related macular degeneration and a mean visual acuity (VA) of 6/20 in the better eye was reported as 62.14 Our residents’ mean VF-14 score in the peripheral loss group was 44, whereas that in a group of glaucomatous patients with a similar AGIS (Advanced Glaucoma Intervention Study) score was in the 60–70 range.15 Our residents’ mean VF-14 score in the overall blur group was 24, and that in a group of patients with cataract with a VA between 6/15 and 6/60 was about 70.5,16 In contrast, the utility values both before and after our residents had performed the daily activities tended to be higher than those of real patients. For example, the utility value for the group of age-related macular degeneration patients, with VA from 6/18 to 6/30, was reported to be 0.57 by the time trade-off method and 0.69 by the standard gamble method.1 The utility value for the group of glaucomatous patients, with a similar median deviation of visual field loss, was 0.64 by the time trade-off method.13 However, the utility value for the group of cataract patients with VA of 6/15 or worse was 0.78 by the time trade-off method and 0.84 by the standard gamble method, similar to our residents’ utility values before the exercises but higher than those of the residents after the exercises.16 The VF-14 score was higher in real patients than in our residents, which is probably related to some degree of adaptation in the patients performing daily activities. The patients in the reports cited above had suffered from visual impairments for a considerable amount of time and had probably developed skills to help them cope with their impairments. This was not the case with our residents, who wore simulators for only a week to complete this study. The higher utility values reported by our residents suggested that, even after the exercises, there was still some disparity between them and the patients with respect to their perceptions of quality of life due to visual impairment. Nevertheless, the disparity decreased after the exercises in both the peripheral loss and the overall blur groups, though not in the other 2 groups. This was probably due to the relatively poor design of the latter 2 simulators. When wearing either the central loss or the hemianopia simulator, the residents could easily avoid the obscured area by unintentionally tilting their head or moving their eye to regain their normal vision. This decreased the disabling effect of the simulators and influenced our residents’ perception of the impairment. Unlike the other 3 types of visual impairment, cataract-related vision loss is now curable. Therefore, the utility value for cataract patients is higher than that for our residents wearing an overall blur simulator. The difference between the 4 simulators was statistically significant when measuring the residents’ mean VF-14 scores and their utilities obtained with the time trade-off method, but not those obtained with the standard gamble method. This was probably due to a difference in the residents’ choice for the desirability of life from perfect health
to death among these 3 methods of measurement. The level of difficulty in both VF-14 and the time trade-off method was scored by a multiple or grading choice, whereas that in the standard gamble method was scored by an all-or-none choice. Given most people’s fear of sudden death, the differences between the simulators in the standard gamble method was less remarkable, and its score was always higher than that with the time trade-off method.17 The results did not differ greatly between junior and senior residents in our study, suggesting that medical knowledge helps very little in appreciating the inconvenience experienced by disabled patients. This observation is supported by a previous report in which clinicians and community members had a similar utility value for age-related macular degeneration, but this was higher than that of the patients.2 Therefore, it is crucial to include both medical knowledge and other training, such as these exercises with low-vision simulators, in low-vision education provided to residents. In summary, our study demonstrates that ophthalmology residents tend to underestimate the impact of functional disability in visually impaired patients. Although the lowvision simulator exercises cannot provide a true experience of visual impairment, they help the residents to better appreciate the inconvenience of these disabilities. We suggest that medical knowledge and appropriate low-vision simulator exercises while performing daily activities are both important in residents’ training. The authors have no proprietary or commercial interest in any materials discussed in this article.
REFERENCES 1. Brown GC, Brown MM, Sharma S. Difference between ophthalmologists’ and patients’ perceptions of quality of life associated with age-related macular degeneration. Can J Ophthalmol 2000;35:127–33. 2. Stein JD, Brown MM, Brown GC, Hollands H, Sharma S. Quality of life with macular degeneration: perceptions of patients, clinicians and community members. Br J Ophthalmol 2003;87:8–12. 3. Schrader GD. Subjective and objective assessments of medical comorbidity in chronic depression. Psychother Psychosom 1997; 66:258–60. 4. Rothwell PM, McDowell Z, Wong CK, Dorman PJ. Doctors and patients don’t agree. Cross sectional study of patients’ and doctors’ perceptions and assessments of disability in multiple sclerosis. BMJ 1997;314:1580–3. 5. Steinberg EP, Tielsch JM, Schein OD, et al. The VF-14: an index of functional impairment in cataract patients. Arch Ophthalmol 1994;112:630–8. 6. Brown GC. Vision and quality-of-life. Trans Am Ophthalmol Soc 1999;92:473–511. 7. Brown MM, Brown GC, Sharma S, Garrett S. Evidence-based medicine, utilities and quality of life. Curr Opin Ophthalmol 1999;10:221–6. 8. Pleis JR, Lethbridge-Çejku M. Summary health statistics for CAN J OPHTHALMOL—VOL. 44, NO. 6, 2009
695
Low-vision simulators and quality of life—Hou et al.
9.
10. 11.
12.
13.
U.S. adults: National Health Interview Survey, 2006. National Center for Health Statistics. Vital Health Stat 2007;10:1–153. Swagerty DL Jr. The impact of age-related visual impairment on functional independence in the elderly. Kans Med 1995;96:24–6. Torrance GW, Feeny D. Utilities and quality-adjusted life years. Int J Technol Assess Health Care 1989;2:559–75. Musch DC, Farjo AA, Meyer RF, Waldo MN, Janz NK. Assessment of health-related quality of life after corneal transplantation. Am J Ophthalmol 1997;124:1–8. Linder M, Chang TS, Scott IU, et al. Validity of the visual function index (VF-14) in patients with retinal disease. Arch Ophthalmol 1999;117:1611–6. Gupta V, Srinivasan G, Mei SS, Gazzard G, Sihota R, Kapoor KS. Utility values among glaucoma patients: an impact on the quality of life. Br J Ophthalmol 2005;89:1241–4.
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14. Riusala A, Sarna S, Immonen I. Visual function index (VF-14) in exudative age-related macular degeneration of long duration. Am J Ophthalmol 2003;135:206–12. 15. Gutierrez P, Wilson MR, Johnson C, et al. Influence of glaucomatous visual field loss on health-related quality of life. Arch Ophthalmol 1997;115:777–84. 16. Saw SM, Gazzard G, Gomezperalta C, Au Eong KG, Seah S. Utility assessment among cataract surgery patients. J Cataract Refract Surg 2005;31:785–91. 17. Wakker P, Stiggelbout A. Explaining distortions in utility elicitation through the rank-dependent model for risky choices. Med Decis Making 1995;15:180–6.
Keywords: low vision, education, assessment