A total of 114 children were recruited in the pre-implementation phase of the study in Amsterdam, Rotterdam, Utrecht and The Hague. Of these, 33 lived in Amsterdam or Rotterdam, and, were not eligible because of long travel distances. Parents of 14 other children could not be reached despite two phone calls and two house calls. Fifteen parents refused to participate in the oral interview: the reason they all gave was that they had no time. Of the 52 parents who responded to the interview, 24 had a ‘moderate’ or ‘poor’ level of fluency in the Dutch language. Sixteen parents were of Dutch origin, 13 Moroccan, 13 Turkish, and ten had other countries of origin. Seven were Christians, 30 were Muslims, seven had no religion and eight had other religious affiliations. The mean age of the children was 4.84 ± 1.24 years when occlusion therapy was started. The mean prescribed occlusion time was 3:37 ± 1:15 hours a day, for 7 days a week, at the initiation of occlusion therapy. The mean initial visual acuity was 0.42 SD 0.33 LogMAR in the amblyopic eye and 0.07 SD 0.11 LogMAR in the better eye.
Data on compliance was available for 45 of the 52 children: in seven cases, data were incomplete due to repeated failure of the ODM. Mean compliance was 56 ± 44 percent. Compliance followed a bimodal distribution (solid polynomial line in Fig. 1) with two peaks: one at 90%, the other at 0%. Twenty-two of the 45 children occluded less than half of the occlusion time prescribed by the orthoptist (Fig. 1).
Fifty-five of the 205 questions were excluded from analysis: 34 did not apply to or were not answered by the majority of parents and 21 were answered unanimously, i.e., all parents answered ‘agree’ or ‘disagree’. Univariate analysis showed that 18 of the remaining 150 variables correlated significantly with the electronically measured compliance. These variables belonged to the domains Income, Health, Family Bonds, Social Contacts, Cultural Integration & Conceptualization, and Lazy Eye. Table 1 depicts the 18 variables that correlated significantly with the electronically measured compliance.
Table 1 In univariate analysis, 18 questions were associated with electronically measured compliance with occlusion therapy. On the left, in italics, all domains are listed. All questions that were not significant were omitted. Mean electronically measured compliance in percentage (in brackets is N) per response on each question is given. * P < 0.01
In the domain Income, low income (i.e., <€1,750 net/month, the average income in the Netherlands [25]) was associated with poor compliance (P = 0.017).
In the domain Health, children of parents who had experienced periods of depression during the previous four weeks had a significantly lower compliance (P = 0.022).
In the domain Family Bonds, two questions were associated with compliance: parents who agreed that grandparents should be prepared to babysit their grandchildren on a regular basis, and who agreed that grown-up children, who lived near their parents, should visit them at least once a week, had a lower compliance (P = 0.001 and P = 0.039 respectively).
Four questions in the domain Social Contacts demonstrated correlations with compliance: parents who had frequent close contact with neighbors demonstrated poor compliance. Children of parents who were members of a social club, for example, a sports club or a religious organization had high compliance (P = 0.003). Parents of 19 children were member of one club; five parents were member of two or more clubs. Twelve parents were member of a religious organization, ten of a sports club, three of a music association or a theatrical company, two of a school association, one of a labor union, and one of a political organization.
In the domain Cultural Integration & Conceptualization in Table 1, eight questions pertaining negative perceptions of the Dutch society correlated with low compliance: parents who agreed with these questions were significantly less compliant (30%-40%) than parents who did not agree with these questions. For example, parents who were of the opinion that it is more important for boys to earn their own money than for girls, that people are getting divorced too easily nowadays and that, in the Netherlands, people speak too openly about sexuality, had a significantly lower compliance (P = 0.020, P = 0.023, and P = 0.026 respectively). Poor compliance was also found in parents who found that elderly people should be able to live with their children, that parents should allow their grown-up children to live in their home, and that the elderly family members have more to say when making an important decision than younger family members (P = 0.014, P = 0.026, and P = 0.005 respectively).
In the domain Lazy Eye, low compliance correlated with the parental opinion that the child had difficulty with playing outside while wearing the patch (P = 0.007). When parents said the child was less active while wearing the patch, compliance was significantly lower (P = 0.046).
No questions in the domain “Religion” were found to be associated with compliance. The kind of religion, differences in interest in religion, frequency of practicing the religion, frequency of visiting religious communities (e.g., the church or mosque), and strict or less strict religious beliefs did not affect compliance with occlusion therapy.
The 18 variables that were significant in univariate analysis were included in the multiple regression analysis. One variable remained significant: "In the Netherlands, people speak too openly about sexuality" (P = 0.002).