Patients characteristics
Criteria collected
|
Number
|
Age : (in months)
|
|
- Between 36 and 59
|
28 % (27/96)
|
- Between 60 and 66
|
22 % (21/96)
|
- Between 67 and 79
|
23 % (22/96)
|
- Between 80 and 112
|
24 % (23/96)
|
Gender :
|
|
- Girls
|
56 % (54/96)
|
- Boys
|
44 % (42/96)
|
Number of previous eye examination:
|
|
- First examination
|
16 % (15/96)
|
- Between 1 and 5
|
38 % (36/96)
|
- Between 6 and 10
|
21 % (20/96)
|
- > 10
|
25 % (24/96)
|
Reason for examination
|
|
- Screening
|
25 % (24/96)
|
- Amblyopia or known risk factor of amblyopia
|
75 % (72/96)
|
Diagnosis :
|
|
Known amblyopia
|
12 % (12/96)
|
Strabismus
|
34 % (33/96)
|
Hypermétropia
|
22 % (21/96)
|
Astigmatism
|
10 % (10/96)
|
Myopia
|
4 % (4/96)
|
Time duration on smartphone or tablet at home per week
|
|
- < 3 hours
|
62 % (60/96)
|
- between 3 and 7 hours
|
22 % (21/96)
|
- between 7 and 14 hours
|
13 % (12/96)
|
- > 14 hours
|
3 % (3/96)
|
Table 1. Patients characteristics
One hundred patients were included between September 2016 and June 2017. The average age was 68 months. Four children were excluded from the analysis for not being able to perform the tests. Characteristics of the 96 patients included are presented in Table 1. Amblyopia was defined as a monocular acuity less than or equal to 6/10 or with a difference in visual acuity greater than or equal to 2/10 between both eyes. Children with uni or bilateral amblyopia were included as amblyopic. Any absence of emmetropia was recorded as myopia, hyperopia or astigmatism.
Principal outcome
The mean visual acuity using the Rossano-Weiss test was -0.22 logMAR or 6.2/10 for the right eye and -0.24 logMAR or 6.1/10 for the left eye. When assessed with the eMOVA test, mean visual acuity was -0.28 logMAR or 5.9/10 for the right eye and -0.24 logMAR or 6.1/10 for the left eye. The mean difference in visual acuity measured between both tests was -0.06 logMAR or 0.3/10 for the right eye and -0.01 logMAR or 0/10 for the left eye. These data related to the principal study outcome are presented in Table 2. The maximum visual acuity achieved with both tests was -0.18 logMAR. The minimum visual acuity assessed was -0.67 logMAR and -1.2 logMAR, respectively, for the Rossano-Weiss test and the eMOVA test. The first quartile, median, third quartile and mode were -0.18 logMAR for all groups. Overall, the differences in visual acuity using both tests were very limited. In order to estimate the equivalence of both tests, a statistical analysis of concordance was conducted. For this analysis, both sets of values were analyzed separately to verify the validity of our results for each eye: first values measured for the right eye and secondly the one for the left eye of each participants. The correlation coefficient r for visual acuity measurement obtained with the Rossano-Weiss test and the eMOVA test was respectively 0.40 (p <0.001 and 95 [0.21-0.55]) for the right eye series and 0.43 (p <0.001 and IC 95 [0.26-0.58]) for the left eye series (Table 2). When visual acuity measured with the Rossano-Weiss test was -0.18 logMAR, 91% of visual acuity scores obtained for the right eyes and 95% of the scores obtained for the left eyes were comparable with the measured obtained with the eMOVA test.The mean difference between both tests was -0.06 logMAR (lower bound: -0.48, upper bound 0.36) for the right eye series and -0.01 logMAR (lower bound: -0,40, upper bound: 0.38) for the left eye series.
|
Right eye series |
Left eye series |
Mean visual acuity (in logMAR) |
|
|
- Rossano-Weiss test |
-0.22 |
-0.24 |
- eMOVA test |
-0.28 |
-0.24 |
Mean difference between both tests |
-0.06 [-0.48 – 0.36] |
-0.01 [-0.40 – 0.38] |
p |
0.006 [-0.10 – 0.02] |
0.006 [-0.10 – 0.02] |
Correlation coefficient |
0.40 |
0.43 |
Table 2. Primary outcome main results presented in logmar On the Bland and Altman analysis (Figure 2), concordance was very good for the highest visual acuities. However, for visual acuity scores lower than -0.6 logMAR, the concordance became less good. The eMOVA test showed better visual acuity measurements compared to the Rossano-Weiss in participant with a low visual acuity.The eMOVA test overestimated visual acuities of 0.06 logMAR compared to the Rossano-Weiss for the right eye series and visual acuity scores of 0.01 logMAR for the left eye series. When using the lower and upper limits, the difference in values obtained between both tests was at most -0.48 logMAR for the right eye series (Figure 2) and -0.40 logMAR for the left eye series (Figure 3).
The mean difference between both tests was -0.06 logMAR in favor of the eMOVA test using the Wilcoxon test. This difference was statistically significant (p = 0.006). The 95% confidence interval of this difference was [-0.10 - 0.02]. These results were the same for both series. This means that at most, the difference in visual acuity measured between the two tests would be 0.10 logMAR.Both analysis, concordance and superiority tests, showed the same tendency: the eMOVA test overestimated visual acuity statistically. However, this difference was not clinically relevant as it would be at most 0,06 logMAR.Analysis of the Bland and Altman graphs showed that measurement concordance decreases when visual acuities are low. Indeed, the concordance was good for the visual acuities comprised of 0 and -0.6 logMAR and became lower for visual acuities lower than -0.6 logMAR (Figure 2). This trend was also observed for the second series (Figure 3).
The results of the Deming regression was: Intercept = 0.14 CI 95 [0.10; 0.18], Slope = 0.28 CI 95 [0.09; 0.47] for the series on the right eyes and Intercept = -0.11 CI 95 [-0.76; 0.54], Slope = 1.64 CI 95 [-1.91; 5.19] for the series on the left eyes.
These results show the absence of systematic and proportional bias for the series on the left eyes. Contrary to these results, systematic and proportional biases are found for the series on the right eyes. However, these biases have no clinical relevance because the average difference found between the visual acuity measurements taken with the eMOVA test and with the Rossano-Weiss test is 0.01 on the Bland et Altmann, which has no clinical consequence.
Secondary outcomes
Results related to secondary outcomes are presented in Table 3. Eighty-four percent (84%) of all children had perfectly understood the testing conditions with a score of 5. Eighty-one percent (81%) of all children presented with an attention score of 5. Eighty-four percent (84%) of all children had a distance score greater than or equal to 4. No statistical difference has been observed when the comparison has been performed between both tests.The mean difference in assessment time duration between both tests was 21 seconds for both eyes checks. The minimum duration was 11 seconds for the Rossano-Weiss test and 23 seconds for the eMOVA test. The maximum duration was 340 seconds for the Rossano-Weiss test and 174 seconds for the eMOVA test. These differences were statistically significant (p <0.001).Overall, we noticed that child's discomfort increased across the testing procedure for both tests. The average FLACC scores obtained before / during / after the test were all lower with the eMOVA test. The test was felt by the children less stressful when performed with the tablet than the Rossano-Weiss test and this difference was statistically significant (p = 0.01).
|
Rossano-Weiss
|
eMOVA
|
p
|
Understanding
|
4.8
|
4.8
|
0.11
|
Attention
|
4.7
|
4.8
|
0.26
|
Respect of distance
|
4.4
|
4.3
|
0.72
|
Duration
|
43
|
64
|
<0.001
|
Total FLACC
|
0.3
|
0.1
|
0.01
|
Table 3. Comparison of secondary outcomes scores.
Testing parameters
The reproducibility of the eMOVA test was calculated on 30 eyes check samples (both eyes of 15 children) which has been performed twice in a row under identical conditions. The reproducibility of the eMOVA test was very good with an intra class correlation coefficient of 0.93 (95% CI [0.87-0.97]). Considering the Rossano-Weiss as the gold standard, we have defined as amblyopic any child with a monocular acuity less than or equal to 6/10 or with a difference in visual acuity greater than or equal to 2/10 between both eyes. The sensitivity observed for the eMOVA test was 56% and its specificity 88%. The negative predictive value of the test was 90% and its positive predictive value 53%. The accuracy of the eMOVA test was 82%.
eMOVA Rossano-Weiss
|
M+
|
M-
|
Total
|
M+
|
10
|
8
|
18
|
M-
|
9
|
69
|
78
|
Total
|
19
|
77
|
96
|
Table 4. Distribution of true positives, true negatives, false positives and false negatives ( M+ corresponds to the presence of amblyopia and M- to its absence).
Test preference
The eMOVA test was mostly chosen by parents and children when we asked them which one of the two tests they would prefer to use for a future eye examination. Eighty-seven percent (87% or 84/96) of the children and 80% (or 77/96) of the parents would choose the eMOVA test.
Sequence effect
No statistical difference regarding the testing order between both tests has been observed after analysis which limits potential sequential bias in our study (p=0.61).