Background
Methods
Participants
-
cataracts that were considered sufficiently severe to impair vision
-
glaucoma
-
diabetic retinopathy sufficiently severe to impair vision
-
degenerative myopia
-
any macular condition other than age-related MD
-
one non-functioning eye for reasons other than age-related MD
-
unable to understand and speak English
Procedure
-
MacDQoL
-
demographic items
-
other vision-related questions followed the MacDQoL and the demographic items. These will be reported fully elsewhere.
-
distance visual acuity, using Bailey-Lovie logMAR charts with Early Treatment for Diabetic Retinopathy Study (ETRDS) protocol [25] for monocular and binocular vision
-
near visual acuity (MNREAD charts with ETDRS protocol) for monocular and binocular vision [26]
-
comfortable visual acuity for monocular and binocular vision. This was computed from time taken to read script of different sizes of print (MNREAD charts with ETDRS protocol). The time taken to read each line was recorded. When the time to read a line increased substantially, this showed that it was no longer 'comfortable' to read that size print and smaller prints [26].
-
contrast sensitivity, using Pelli-Robson charts [27] for monocular and binocular vision
-
presence of distortion or a scotoma in central 10 degrees of vision (Amsler grid with concentric circles) for monocular and binocular vision. Patients fixated the central spot and identified the presence of distorted or missing grid lines in their peripheral field [28].
-
colour vision (PV-16 colour vision test for visually impaired people) for binocular vision only. This consisted of a number of coloured blocks that the participant was asked to arrange in the order of the spectrum and is an enlarged version of the D-15 colour vision test [29].
-
recovery from glare (Eger stressometer glare test) for binocular vision only. This test recorded the number of seconds taken to be able to read the smallest readable print again, after a brief flash of light [30].
Statistical methods
Factor structure
Internal consistency reliability
Redundancy
Construct validity
Results
Participants
Demographic and clinical data | N (valid %) | |
---|---|---|
Sex | women | 99 (63.5) |
men | 57 (36.5) | |
Marital status | married or living with partner | 74 (47.4) |
widowed | 68 (43.6) | |
divorced or separated | 8 (5.1) | |
single | 6 (3.6) | |
Number of eyes affected by MD | one | 6 (3.8) |
two | 150 (96.2) | |
Type of MD | wet only | 90 (57.7) |
dry only | 19 (12.2) | |
wet and dry | 42 (26.9) | |
wet and type MD in 2nd eye not specified | 4 (2.6) | |
type of MD not specified | 1 (0.6) | |
Both eyes diagnosed at same time | yes | 46 (32.6) |
no | 95 (67.4) | |
missing | 15 | |
Registration status | blind | 8 (5.4) |
partially sighted | 67 (45.6) | |
not registered | 72 (46.2) | |
missing | 9 |
Item | Impact score frequencies | Importance score frequencies | |||||||
---|---|---|---|---|---|---|---|---|---|
-3
|
-2
|
-1
|
0
|
1
|
3
|
2
|
1
|
0
| |
household tasks | 46 | 56 | 26 | 28 | 0 | 55 | 76 | 20 | 5 |
personal affairs | 65 | 41 | 22 | 28 | 0 | 75 | 57 | 17 | 6 |
shopping | 67 | 43 | 24 | 22 | 0 | 47 | 76 | 23 | 10 |
*work | 1 | 2 | 0 | 0 | 0 | 1 | 1 | 1 | 0 |
*personal relationship | 10 | 12 | 12 | 47 | 0 | 58 | 19 | 3 | 0 |
*family life | 27 | 35 | 24 | 60 | 3 | 108 | 36 | 4 | 1 |
friends and social | 33 | 43 | 26 | 54 | 0 | 63 | 71 | 14 | 8 |
physical appearance | 22 | 22 | 41 | 71 | 0 | 67 | 57 | 26 | 6 |
do physically | 44 | 50 | 37 | 25 | 0 | 80 | 62 | 12 | 2 |
get out and about | 62 | 34 | 30 | 30 | 0 | 92 | 50 | 12 | 2 |
*long journeys | 28 | 37 | 13 | 24 | 1 | 27 | 41 | 26 | 10 |
*holidays | 38 | 33 | 23 | 27 | 0 | 38 | 48 | 27 | 8 |
leisure activities | 97 | 37 | 16 | 13 | 0 | 64 | 65 | 21 | 6 |
hobbies | 68 | 46 | 19 | 22 | 0 | 63 | 64 | 23 | 6 |
self-confidence | 41 | 55 | 29 | 31 | 0 | 80 | 58 | 12 | 6 |
motivation | 31 | 48 | 31 | 45 | 1 | 51 | 64 | 33 | 8 |
people's reaction | 12 | 25 | 27 | 91 | 0 | 48 | 66 | 27 | 14 |
society's reaction | 14 | 25 | 26 | 88 | 0 | 28 | 61 | 43 | 22 |
future | 43 | 56 | 27 | 30 | 0 | 52 | 60 | 33 | 11 |
financial situation | 11 | 13 | 12 | 119 | 1 | 38 | 79 | 30 | 9 |
independence | 71 | 37 | 27 | 21 | 0 | 97 | 45 | 10 | 4 |
do for others | 56 | 46 | 23 | 31 | 0 | 66 | 65 | 21 | 4 |
mishaps | 40 | 34 | 43 | 39 | 0 | 69 | 60 | 21 | 6 |
enjoy meals | 31 | 33 | 26 | 66 | 0 | 49 | 72 | 26 | 9 |
time taken | 41 | 49 | 32 | 33 | 0 | 30 | 56 | 45 | 24 |
enjoy nature | 48 | 47 | 23 | 38 | 0 | 56 | 62 | 26 | 12 |
The MacDQoL: range of responses
Domains in descending order of impact score (n) | Mean impact score (s.d.) | Mean importance rating (s.d.) | Rank order of weighted impact |
---|---|---|---|
1 work (3) | -2.33 (1.08) | 2 (1) | 3 |
2 leisure activities (155) | -2.31 (0.96) | 2.2 (0.81) | 2 |
3 hobbies (156) | -2.03 (1.07) | 2.18 (0.82) | 4 |
4 independence (156) | -2.01 (1.08) | 2.51 (0.73) | 1 |
5 shopping (156) | -1.99 (1.07) | 2.03 (0.84) | 9 |
6 personal affairs (156) | -1.92 (1.13) | 2.3 (0.82) | 5 |
7 get out and about (156) | -1.82 (1.16) | 2.49 (0.7) | 6 |
8 do for others (156) | -1.81 (1.13) | 2.24 (0.78) | 7 |
9 household tasks (156) | -1.77 (1.06) | 2.16 (0.77) | 12 |
10 do physically (156) | -1.72 (1.04) | 2.41 (0.69) | 8 |
11 future (156) | -1.72 (1.07) | 1.98 (0.91) | 13 |
12 self-confidence (156) | -1.68 (1.07) | 2.36 (0.79) | 11 |
13 holidays (121) | -1.68 (1.14) | 1.96 (0.9) | 14 |
14 nature (156) | -1.67 (1.15) | 2.04 (0.91) | 10 |
15 long journeys (103) | -1.65 (1.14) | 1.82 (0.93) | 17 |
16 time taken (156) | -1.63 (1.09) | 1.59 (0.97) | 19 |
17 mishaps (156) | -1.48 (1.13) | 2.23 (0.83) | 15 |
18 motivation (156) | -1.40 (1.12) | 2.01 (0.86) | 20 |
19 friends and social (156) | -1.35 (1.16) | 2.21 (0.81) | 18 |
20 enjoy meals (156) | -1.19 (1.18) | 2.03 (0.85) | 21 |
21 family life (149) | -1.15 (1.2) | 2.68 (0.56) | 16 |
22 physical appearance (156) | -1.14 (1.08) | 2.19 (0.85) | 22 |
23 personal relationship (81) | -0.81 (1.10) | 2.69 (0.54) | 23 |
24 society's reaction (153) | -0.77 (1.03) | 1.62 (0.94) | 25 |
25 people's reaction (155) | -0.73 (1.00) | 1.95 (0.92) | 24 |
26 financial situation (156) | -0.45 (0.92) | 1.94 (0.82) | 26 |
Transforming the data
Structure of 26-item MacDQoL
(a) Not applicable items scored as zero
(b) Not applicable items scored as missing, using pairwise deletion
(c) Removal of items
(d) Structure of the 23-item MacDQoL
Item | Rotated Component Matrix Four factor solution (variance explained = 64.3%) | Single factor solution (variance explained = 49%) | |||
---|---|---|---|---|---|
Factor 1 | Factor 2 | Factor 3 | Factor 4 | Factor 1 | |
household tasks |
0.734
| 0.098 | 0.136 | 0.312 |
0.6869
|
personal affairs |
0.754
| 0.254 | 0.146 | 0.099 |
0.7264
|
shopping |
0.747
| 0.042 | 0.317 | 0.219 |
0.7145
|
personal relationship | 0.210 | -0.062 | 0.132 |
0.778
|
0.4219
|
family | 0.179 |
0.411
| 0.199 |
0.629
|
0.6127
|
friends and social | 0.252 |
0.604
| 0.095 |
0.541
|
0.6961
|
appearance | 0.342 | 0.210 |
0.443
| 0.181 |
0.5821
|
do physically |
0.587
|
0.473
| 0.269 | 0.023 |
0.7659
|
get out and about |
0.699
| 0.324 | 0.252 | 0.125 |
0.7809
|
holidays | 0.199 |
0.793
| 0.188 | 0.050 |
0.6582
|
hobbies/leisure |
0.589
|
0.549
| 0.081 | 0.091 |
0.7484
|
self-confidence |
0.495
| 0.282 | 0.259 | 0.266 |
0.6691
|
motivation | 0.387 |
0.444
| 0.310 | 0.291 |
0.7150
|
peoples reaction | 0.265 | 0.259 |
0.702
| -0.071 |
0.5935
|
future | 0.189 | 0.284 |
0.533
| 0.162 |
0.5541
|
finances | 0.048 | -0.070 |
0.747
| 0.148 | 0.3558 |
independence |
0.716
|
0.444
| 0.173 | 0.158 |
0.8345
|
do for others |
0.679
| 0.322 | 0.227 | 0.099 |
0.7491
|
mishaps | 0.387 |
0.651
|
0.419
| 0.176 |
0.7906
|
enjoy meals | 0.375 | 0.349 |
0.538
| 0.160 |
0.7141
|
time taken | 0.321 |
0.460
|
0.466
| 0.204 |
0.7208
|
nature | 0.305 |
0.752
| 0.150 | 0.127 |
0.7122
|
Reliability of the 22-item MacDQoL AWI scale score
MacDQoL item | Scale mean if item deleted | Scale variance if item deleted | Corrected item-total correlation | Alpha if item deleted |
---|---|---|---|---|
household tasks | -71.92 | 1890.0 | 0.65 | 0.9414 |
personal affairs | -71.19 | 1855.3 | 0.68 | 0.9408 |
shopping | -71.53 | 1876.8 | 0.68 | 0.9410 |
personal relationship | -74.74 | 1967.5 | 0.39 | 0.9446 |
family | -72.93 | 1879.3 | 0.58 | 0.9426 |
friends and social | -72.80 | 1875.0 | 0.66 | 0.9412 |
appearance | -73.65 | 1915.5 | 0.54 | 0.9428 |
do physically | -71.57 | 1858.6 | 0.72 | 0.9402 |
get out and about | -71.32 | 1838.4 | 0.74 | 0.9399 |
holidays | -73.16 | 1882.9 | 0.61 | 0.9419 |
hobbies/leisure | -70.87 | 1874.7 | 0.71 | 0.9405 |
confidence | -71.66 | 1879.3 | 0.63 | 0.9417 |
motivation | -72.83 | 1876.9 | 0.68 | 0.9409 |
people's reaction | -74.16 | 1918.8 | 0.55 | 0.9427 |
future | -72.03 | 1909.2 | 0.52 | 0.9433 |
financial situation | -74.89 | 1987.8 | 0.33 | 0.9452 |
independence | -70.57 | 1822.7 | 0.80 | 0.9390 |
do for others | -71.45 | 1847.3 | 0.71 | 0.9404 |
mishaps | -72.31 | 1839.5 | 0.76 | 0.9397 |
meals | -73.30 | 1882.1 | 0.68 | 0.9410 |
time | -72.88 | 1870.7 | 0.69 | 0.9408 |
nature | -72.08 | 1866.9 | 0.67 | 0.9410 |
Variable | Mean | s.d. | Median | |
---|---|---|---|---|
MacDQoL present QoL overview | 0.90 | 1.13 | 1 | |
MacDQoL MD-specific overview | -2.13 | 0.89 | -2 | |
MacDQoL AWI | -3.57 | 2.14 | -3.7 | |
Distance VA (logMAR) | better eye | 0.42 | 0.46 | 0.39 |
worse eye | 1.23 | 0.95 | 0.95 | |
binocular | 0.39 | 0.46 | 0.37 | |
Near VA | better eye | 0.45 | 0.43 | 0.3 |
worse eye | 1.09 | 0.58 | 1.1 | |
binocular | 0.42 | 0.41 | 0.30 | |
Contrast sensitivity | better eye | 1.01 | 0.77 | 1.05 |
worse eye | 0.43 | 0.49 | 0.15 | |
binocular | 1.01 | 0.44 | 1.05 | |
Comfortable VA | 0.50 | 0.35 | 0.4 | |
Colour recognition (errors) | 21.60 | 7.74 | 21.9 | |
Glare test recovery (seconds) | 11.02 | 8.94 | 8.5 |
Missing data
Correlation between MacDQoL AWI and overview items
Construct validity
Present QoL | p-value | MD-specific QoL | p-value | AWI | p-value | ||
---|---|---|---|---|---|---|---|
Distance VA | better eye | -0.301 | <0.001* | -0.310 | <0.001* | -0.431 | <0.001* |
Near VA | better eye | -0.327 | <0.001* | -0.192 | 0.017 | -0.326 | <0.001* |
Contrast sensitivity | better eye | 0.200 | 0.012 | 0.300 | 0.001* | 0.392 | <0.001* |
Colour vision | binocular | -0.204 | 0.011 | -0.291 | <0.001* | -0.417 | <0.001* |
Comfortable VA | binocular | -0.207 | 0.012 | -0.121 | >0.05 | -0.283 | <0.001* |
Glare test | binocular | -0.069 | >0.05 | -0.010 | >0.05 | 0.022 | >0.05 |
Scotoma | Distortion | |||
---|---|---|---|---|
Yes (valid%) | No (valid%) | Yes (valid%) | No (valid%) | |
Right eye | 80 (52.3) | 73 (47.7) | 68 (44.4) | 85 (55.6) |
Left eye | 75 (48.7) | 79 (51.3) | 50 (32.7) | 103 (67.3) |
Binocular | 39 (25.7) | 113 (74.3) | 58 (37.9) | 95 (62.1) |