Two questionnaires used to measure quality of life in people with strabismus overlap but differ in important areas, according to researchers.
Of the two, only the Adult Strabismus Quality of Life Questionnaire (AS-20) includes functional problems such as avoidance of reading, difficulty in concentrating, eye stress, reading problems, inability to enjoy hobbies and the need for frequent breaks when reading, wrote Dr Elizabeth S. van de Graaf of the University Medical Centre Rotterdam in the Netherlands, and colleagues.
They put this down to AS-20 only being designed to evaluate strabismus, whereas the Amblyopia & Strabismus Questionnaire (A&SQ) looks at both strabismus and amblyopia. In addition, there are differences in the populations used in developing these instruments. The researchers outlined their findings in Graefe’s Archive for Clinical and Experimental Ophthalmology.
Amblyopia and strabismus can both affect patients’ quality of life, and clinicians should take this into consideration when prescribing treatments. Therefore, it is important to know how the two most widely used questionnaires for evaluating quality of life in strabismus compare with each other, the researchers wrote.
The AS-20 was originally designed using two samples of adult patients who came for treatment, most of them with diplopia and adult-onset strabismus. The first group of patients responded to 11 open-ended questions to generate 1,301 key phrases. Meeting with the second group, the designers reduced the pool of phrases to 20 items and categorised them into two subscales.
The A&SQ was developed by an expert focus group and validated among adults with childhood strabismus and/or amblyopia, whose complaints were categorised into themes before being defined according to domains of strabismus- and amblyopia-related qualify of life. The designers identified six factors that together explained 70.5% of the total variance among patients.
They excluded functional problems because they did not think asthenopic items were sufficiently specific for strabismus.