Visual acuity and reading print size requirements in children with vision impairment.

Clinical Relevance: The support of students with a vision impairment throughout education could be enhanced by assessing the functional reading ability of the individual. This visual assessment could inform educators of individualised student needs and potentially improve the academic achievement for these students.

Background: Support for children with a vision impairment within a classroom is typically based on clinical findings of distance visual acuity and visual fields. Therefore, determining optimal print size for reading is essential to ensure best academic outcomes. Secondary aims were to investigate the possible impact of underlying pathology on reading ability.

Methods: Forty-seven participants were recruited from a state-wide support service for children with a vision impairment in South Australia. Three visual acuity groups were formed based on World Health Organisation definitions of mild, moderate, and severe vision impairment. Correlation between clinical measures of distance visual acuity using the Freiburg Visual Acuity Test, were compared with reading acuity and critical print size (smallest font before reading speed reduced) using Minnesota low vision reading chart (MNREAD).

Results: No significant correlations were found for mild (0.20-0.49 logMAR) and severe (1.00-1.52 logMAR) vision impairment groups between distance visual acuity and reading acuity read ( = .64, CI [-.585, .395]/ = .82, CI [-.48, .58]) or critical print size , CI [-.57, .45]/ = .43, CI [-.34, .68]. A significant correlation was found for the moderate vision impairment group: 0.50-0.99 logMAR for minimum reading acuity  < .001, CI [.44, .91]) and critical print size ( = .03, CI [.05, .80]).

Conclusions: Standard clinical measures of distance visual acuity are an unpredictable estimate of reading ability in children with mild and severe vision impairment. Additional measures of functional near reading ability could provide a more meaningful indicator of reading ability and help provide optimum support to students through education.