Visusevaluierung in einer historischen Kohorte von 137 okkludierten Patienten, 30 - 35 Jahre nach Ende der Okklusionsbehandlung

Long-term follow-up of an amblyopia treatment study: change in visual acuity 15 years after occlusion therapy

Purpose

To determine change in visual acuity (VA) in the population of a previous amblyopia treatment study (Loudon 2006) and assess risk factors for VA decrease.

Methods

Subjects treated between 2001 and 2003 were contacted between December 2015 and July 2017. Orthoptic examination was conducted under controlled circumstances and included subjective refraction, best corrected VA, reading acuity, binocular vision, retinal fixation, cover‐uncover and alternating cover test. As a measure for degree of amblyopia, InterOcular VA Difference (IOD) at the end of occlusion therapy was compared with IOD at the follow‐up examination using Wilcoxon’s signed‐rank test. Regression analysis was conducted to determine the influence of clinical and socio‐economic factors on changes in IOD.

Results

Out of 303 subjects from the original study, 208 were contacted successfully, 59 refused and 15 were excluded because of non‐amblyopic cause of visual impairment. Mean IOD at end of therapy (mean age 6.4 years) was 0.11 ± 0.16 logMAR, and IOD at follow‐up examination (mean age 18.3 years) was 0.09 ± 0.21 logMAR; this difference was not significant (p = 0.054). Degree of anisometropia (p = 0.008; univariable analysis), increasing anisometropia (p = 0.009; multivariable), eccentric fixation (p < 0.001; univariable and multivariable); large IOD (p < 0.001; univariable and multivariable) and non‐compliance during therapy (p = 0.028; univariable) were associated with IOD increase.

Conclusion

Long‐term results of occlusion therapy were good. High or increasing anisometropia, eccentric fixation and non‐compliance during occlusion therapy were associated with long‐term VA decrease. Subjects with poor initial VA had a larger increase despite little patching, but often showed long‐term VA decrease.

Differences in quality-of-life dimensions of Adult Strabismus Quality of Life and Amblyopia & Strabismus Questionnaires

Purpose

The Adult Strabismus Quality of Life Questionnaire (AS-20) and the Amblyopia & Strabismus Questionnaire (A&SQ) both measure health-related quality of life in strabismus patients. We evaluated to what extent these instruments cover similar domains by identifying the underlying quality-of-life factors of the combined questionnaires.

Methods

Participants were adults from a historic cohort with available orthoptic childhood data documenting strabismus and/or amblyopia. They had previously completed the A&SQ and were now asked to complete the AS-20. Factor analysis was performed on the correlation-matrix of the combined AS-20 and A&SQ data to identify common underlying factors. The identified factors were correlated with the clinical variables of angle of strabismus, degree of binocular vision, and visual acuity of the worse eye.

Results

One hundred ten patients completed both questionnaires (mean age, 44 years; range, 38–51 years). Six factors were found that together explained 78% of the total variance. The factor structure was dominated by the first four factors. One factor contained psychosocial and social-contact items, and another factor depth-perception items from both questionnaires. A third factor contained seven items—only from the AS-20—on eye strain, stress, and difficulties with reading and with concentrating. A fourth factor contained seven items—only from the A&SQ—on fear of losing the better eye and visual disorientation, specific for amblyopia. Current visual acuity of the worse eye correlated with depth-perception items and vision-related items, whereas current binocular vision correlated with psychosocial and social-contact items, in 93 patients.

Conclusions

Factor analysis suggests that the AS-20 and A&SQ measure a similar psychosocial quality-of-life domain. However, functional problems like avoidance of reading, difficulty in concentrating, eye stress, reading problems, inability to enjoy hobbies, and need for frequent breaks when reading are represented only in the AS-20. During the development of the A&SQ, asthenopia items were considered insufficiently specific for strabismus and were excluded a priori. The patients who generated the items for the AS-20 had, in majority, adulthood-onset strabismus and diplopia and were, hence, more likely to develop such complaints than our adult patients with childhood-onset strabismus and/or amblyopia.

Inventory of current EU paediatric vision and hearing screening programmes

OBJECTIVE

To examine the diversity in paediatric vision and hearing screening programmes in Europe.

METHODS

Themes for comparison of screening programmes derived from literature were used to compile three questionnaires on vision, hearing, and public health screening. Tests used, professions involved, age, and frequency of testing seem to influence sensitivity, specificity, and costs most. Questionnaires were sent to ophthalmologists, orthoptists, otolaryngologists, and audiologists involved in paediatric screening in all EU full-member, candidate, and associate states. Answers were cross-checked.

RESULTS

Thirty-nine countries participated; 35 have a vision screening programme, 33 a nation-wide neonatal hearing screening programme. Visual acuity (VA) is measured in 35 countries, in 71% of these more than once. First measurement of VA varies from three to seven years of age, but is usually before age five. At age three and four, picture charts, including Lea Hyvarinen, are used most; in children over four, Tumbling-E and Snellen. As first hearing screening test, otoacoustic emission is used most in healthy neonates, and auditory brainstem response in premature newborns. The majority of hearing testing programmes are staged; children are referred after 1-4 abnormal tests. Vision screening is performed mostly by paediatricians, ophthalmologists, or nurses. Funding is mostly by health insurance or state. Coverage was reported as >95% in half of countries, but reporting was often not first-hand.

CONCLUSION

Largest differences were found in VA charts used (12), professions involved in vision screening (10), number of hearing screening tests before referral (1-4), and funding sources (8).

Effectiveness of screening for amblyopia and other eye disorders in a prospective birth cohort study

OBJECTIVE

To establish whether the current vision screening practice in the Netherlands is effective in preventing permanent visual loss and to estimate the sensitivity of the programme.

SETTINGS

In the Netherlands, all children are invited for preverbal (1, 3, 6-9 and 14-24 months) and preschool (36, 45, and 60-72 months) vision screening. Screening attendance is high, but the effectiveness in reducing amblyopia is unknown.

METHODS

In a 7-year cohort study, 4624 children born in the city of Rotterdam between 16 September 1996 and 15 May 1997 were followed through all routine vision screening examinations. At age seven, visual acuity (VA) of children still living in Rotterdam was assessed by study orthoptists. In case of VA > 0.1 logMAR in one or both eyes, two or more logMAR lines of interocular difference or eye disorders like strabismus, children underwent a more intensive eye examination.

RESULTS

Attendance at the 9-month screening was 89%, decreasing to about 75% at later examinations. Of preverbal tests, 2.5% were positive, and of preschool tests, 10%. In total, 19% of children had a positive vision screening test at least once. Amblyopia prevalence was 3.4%. Sensitivity of the vision screening programme was 73% and specificity 83%. At age seven, 0.7-1.2% (confirmed vs final exam) of the children had a VA > 0.3 logMAR in the worse eye compared with 2-3.9% (in literature) reported prevalence in non-screening situations. Children who were less frequently screened had a higher chance of poor vision (>0.3 logMAR) at age seven.

CONCLUSION

The Dutch child vision screening programme may reduce the risk of persistent amblyopia (VA > 0.3 logMAR) at age seven by more than half.

Utility analysis of disability caused by amblyopia and/or strabismus in a population-based, historic cohort

Background

Amblyopia (prevalence 3.4%) is in principle treatable, but approximately one quarter of children do not reach reading acuity in the amblyopic eye. Adults with persistent amblyopia and/or strabismus experience a decrease in quality of life. This was now quantified by patient-perceived utility values.

Methods

Subjects were born 1962–1972 and had been treated by occlusion therapy for amblyopia by one orthoptist 30–35 years ago. All children in Waterland with amblyopia and/or strabismus had been referred to this orthoptist. Utilities were derived by methods of time trade-off, TTO (lifetime traded against perfect vision) and standard gamble, SG (death risk accepted for perfect vision). Most troubling eye disorder (low acuity of the amblyopic eye, lacking stereopsis or strabismus) was chosen and ranked among nine chronic disorders according to the subject’s perceived severity.

Results

From 201 patients that could be contacted 35 years after occlusion therapy — out of 471 who had been occluded — 135 were included: 17 could not be reached, 34 refused, and 15 had other reasons to not participate. Mean age was 40.86 years; 53% were male. Seventy percent were willing to trade lifetime according to the TTO method; its mean (log) utility was 0.963, i.e., a decrease in quality of life of 3.7%. Thirty-seven percent accepted death risk according to the SG method; its mean utility was 0.9996. TTO outcomes correlated with current near and distance visual acuity. Low acuity of the amblyopic eye, chosen as most troubling eye disorder, ranked slightly less severe than tooth decay.

Conclusion

Amblyopia and/or strabismus patients had a slightly decreased utility. The decrease is small but still important in the cost-effectiveness of vision screening because these conditions occur very frequently.

Construct validation of the Amblyopia and Strabismus Questionnaire (A&SQ) by factor analysis

Background

The Amblyopia and Strabismus Questionnaire (A&SQ) was previously developed to assess quality of life (QoL) in amblyopia and/or strabismus patients. Here, factor analysis with Varimax rotation was employed to confirm that the questions of the A&SQ correlated to dimensions of quality of life (QoL) in such patients.

Methods

Responses on the A&SQ from three groups were analyzed: healthy adults (controls) (n = 53), amblyopia and/or strabismus patients (n = 72), and a historic cohort of amblyopes born between 1962-1972 and occluded between 1968–1974 (n = 173). The correlations among the responses to the 26 A&SQ items were factor-analysed by Principal Component Analysis (PCA). As the development of the A&SQ was intuitive-deductive, it was expected that the pattern of correlation could be explained by the five a priori hypothesized dimensions: fear of losing the better eye, distance estimation, visual disorientation, diplopia, and social contact and cosmetic problems. Distribution of questions along the factors derived by PCA was examined by orthogonal Varimax rotation.

Results

Data from 296 respondents were analyzed. PCA provided that six factors (cutoff point eigenvalue >1.0) accumulatively explained 70.5% of the variance. All A&SQ dimensions but one matched with four factors found by Varimax rotation (factor loadings >0.50), while two factors pertained to the fifth dimension. The six factors explained 33.7% (social contact and cosmetic problems); 10.3% (near distance estimation); 8.7% (diplopia); 7.2% (visual disorientation); 6.3% (fear of losing the better eye); and 4.3% (far distance estimation), together 70.48% of the item variance.

Conclusion

The highly explained variance in the A&SQ scores by the factors found by the PCA confirmed the a priori hypothesized dimensions of this QoL instrument.

Amblyopia and Strabismus Questionnaire (A&SQ): clinical validation in a historic cohort

BACKGROUND

We recently developed the Amblyopia & Strabismus Questionnaire (A&SQ) to assess the quality of life in amblyopia and/or strabismus patients, and evaluated its content and criterion validity. The A&SQ was now validated clinically by correlating its outcome with past and current orthoptic parameters in a historic cohort of amblyopia and/or strabismus patients.

METHODS

The cohort was derived from all 471 patients who were treated by occlusion therapy in the Waterland Hospital in Purmerend between 1968 and 1974 and born between 1962 and 1972. All children with insufficient visual acuity from the Waterland area had been referred to a single ophthalmologist and orthoptist. Of these, 203 were traced, and 174 filled out the A&SQ. In 137 of these, binocular vision, visual acuity, and angle of strabismus were reassessed 30-35 years after occlusion therapy. These clinical parameters were correlated with the five A&SQ domains: "distance estimation", "visual disorientation", "fear of losing the better eye", "diplopia", and "social contact and cosmetic problems".

RESULTS

The current acuity at distance of the amblyopic eye and reading acuity of the amblyopic eye correlated significantly with all five A&SQ domains (significance level P = 0.01-P = 0.05). Weaker correlations were found for binocularity. In spite of the expectation that stereopsis should strongly correlate with the domain "distance estimation", and angle of strabismus with the domain "social contact and cosmetic problems", the acuity of the amblyopic eye was the overall dominant parameter.

CONCLUSIONS

The adult acuity of the amblyopic eye seems the most important clinical determinant for quality of life in amblyopia and/or strabismus patients, even in domains of distance estimation, visual disorientation, and social contact and cosmetic problems, although intermediate determinants cannot be excluded.