infantile esotropia and their proxy/parents suffered from various problems. However, there is no specific tool to measure their quality of life in our native language. The objective of this study is to develop, validate and evaluate new quality of life questionnaire in children with infantile esotropia and their proxy/parents. The study was conducted from 2016 to 2019. The questionnaire was developed based on literature review, survey, interview and brainstorming with experts. A validation study was conducted on the children and their proxy/parents followed by a cross-sectional study to test the questionnaire. The health related quality of life scores were compared to normal children and their proxy/parents, and between pre-operative and postoperative surgery. A new 3-version questionnaire in Bahasa Malaysia for child 5-8 years (2 subthemes, 10 items), child 9-17 years (2 subthemes, 10 items), and their proxy/parents (4 subthemes, 25 items) was developed. All items in the three version questionnaires had satisfactory content evidence (scale level-content validity index, averaging method > 0.8), and good response process evidence (scale-level face validity index, averaging method >0.8). All questionnaires were found to have high internal consistency (Cronbach’s alpha: 0.84-0.87 (5-8 years old), 0.83-0.86 (9-17 years old), and 0.85-0.89 (proxy/parent); acceptable intraclass correlation coefficients (r=0.497, p<0.01 (5-8 years old), r=0.728, p<0.01 (9-17 years old) and r=0.746, p<0.01(proxy/parents); and significant correlations with the IXTQ (r=0.780, p<0.01 (5-8 years old), r=0.602, p<0.01 (9-17 years old) and r=0.444, p<0.01 (proxy/parent). A statistical significant difference was found between the mean total scores in children with infantile esotropia and their proxy/parents, and normal children and their proxy/parents (p <0.001). No significant association was found between the mean total scores of the children and all factors (gender, angle of deviation and stereopsis, p>0.05). Strabismus surgery had significantly improved the HRQoL scores (68.00 preoperatively to 89.36 postoperatively (p < 0.001) for 5-8 years old group; and 78.07 preoperatively to 90.21 postoperatively (p < 0.001) for 9-17 years old group). A new valid and reliable 3-version HRQoL questionnaire for children with infantile esotropia and their proxy/parents, consists of Child (5-8 years old), Child (9-17 years old) and Proxy/parent questionnaires has been developed. The children and their proxy/parents had lower HRQoL compared to normal children and their proxy/parents. Strabismus surgery successfully improved the HRQoL of the children.