Oculomotor Dysfunction, Stereoacuity Deficits Create Reading Issues in Amblyopia

Reading difficulties among patients with amblyopia are associated with oculomotor dysfunction and stereoacuity deficits, according to a study published in the Journal of the Neurological Sciences.

Researchers enrolled 23 patients with amblyopia (mean age, 16.4 years) including participants with no nystagmus (n=9), patients with fusion maldevelopment nystagmus (FMN; n=5), and individuals with nystagmus lacking structural anomalies and not meeting criteria for FMN or infantile nystagmus (n=9), along with healthy control individuals (n=9; mean age, 14.6 years) in the study. Infrared video-oculography was used to collect eye movement and fixation data while participants read 6 paragraphs written at a grade level of 3 to 5. Reading speed, saccades, and eye fixation measurements were recorded and compared between groups. Tasks were evaluated under amblyopic eye viewing, fellow eye viewing, and binocular viewing. In control group participants, the right eye was considered to be the fellow eye while the left eye was considered to be the amblyopic eye for comparative purposes.  

According to the report, reading speed was faster among control individuals compared with participants with amblyopia under binocular viewing (268.16 vs 174.4 words per minute [wpm]; P <.005), fellow eye viewing (235.65 vs 169.26 wpm; P =.005), and amblyopic eye viewing (245.05 vs 148.72 wpm; P <.0005). Participants with amblyopia had a greater total fixation duration compared with control group participants under all 3 viewing conditions (binocular: 51.28 vs 34.71 seconds; fellow eye: 52.37 vs 34.22 seconds; amblyopic eye: 52.50 vs 34.87 seconds; P ≤.007 for all). Patients with amblyopia also made more progressive and regressive saccades under all viewing conditions compared with control individuals, but these values failed to achieve statistical significance under amblyopic eye viewing conditions (progressive: P =.16; regressive: P =169).  

“Our data suggest that patients with moderate to severe amblyopia and poor depth perception are particularly more likely to experience reading difficulties and may benefit from proper academic accommodations,” according to the researchers. “Our findings support previous suggestions that there may be some benefit in including standardized reading charts in assessing visual functions in patients with amblyopia.”

Study limitations include a failure to evaluate reading comprehension in participants.