JAMA Ophthalmology Journal Club Slides: Amblyopia and Visual-Auditory Speech Perception

1. JAMA Ophthalmology Journal Club Slides:Amblyopia and Visual-Auditory Speech Perception Burgmeier R, Desai RU, Farner KC, et al. The effect of amblyopia on visual-auditory speech perception: why mothers may say “look at me when I’m talking to you.” JAMA Ophthalmol. Published online September 11, 2014. doi:10.1001/jamaophthalmol.2014.3307.

2. Introduction • Speech perception is a multimodal phenomenon, integrating auditory input with the visual input of the speaker’s oral and extraoral facial movement. • One of the most striking demonstrations of how vision influences the perception of sound is the McGurk effect, demonstrated on the next slide. • When viewing the video, keep your eyes open looking at the screen and have the speaker volume raised. Which sounds do you hear?

3. Introduction McGurk Effect Video

4. Introduction The McGurk Effect

5. Objective • To determine whether a history of amblyopia is associated with abnormal visual-auditory speech integration. • Amblyopic children were hypothesized to less frequently perceive /ta/.

6. Methods • Study Design: Retrospective observational study at an academic pediatric ophthalmologic clinic with an average of 4 years of follow-up. • Participants:Participants were at least 3 years of age. Amblyopic participants (n = 24) had best-corrected visual acuity of 20/20 in their nonamblyopic eye. Controls (n = 9) had visual acuity of 20/20 OU. Exclusion criteria were any history of developmental delay, neurologic disorders (eg, seizure, brain injury, cerebrovascular accident, congenital malformation, neoplasm, or autism spectrum disorder), or hearing disorders. • Exposures:Participants were presented with the McGurk effect video and asked to report which sound was perceived: /ka/, /pa/, or /ta/. All participants viewed the stimuli binocularly; those who wore corrective spectacles were tested while wearing them. A subset of the participants with amblyopia were additionally tested monocularly.

7. Methods • Participants were also presented with audio-only /pa/ and /ka/ stimuli (ie, with a blank screen). Those who did not correctly perceive these stimuli in ≥66% of trials were excluded from analysis. • Participants were also excluded if they incorrectly perceived a visual-only /pa/ stimulus (ie, with no audio) or the normal bimodal audio-visual /pa/ and audio-visual /ka/ stimuli. • Participants who perceived the McGurk effect (ie, visual /ka/ with audio /pa/) in ≥80% of trials were considered to have normal visual-auditory fusion, whereas those who perceived the effect in <20% of trials were considered to have abnormal visual-auditory fusion. • Resolution of amblyopia was considered to have occurred when the patient’s visual acuity was equal in both eyes and patching was no longer required.

8. Results • The McGurk effect was perceived by 11 of 24 participants with amblyopia (45.8%) and all 9 controls (100%) (adjusted odds ratio, 22.3 [95% CI 1.2-426.0]; P = .005). • The McGurk effect was perceived by all the participants with amblyopia that had resolved by 5 years of age and by all the participants whose onset of amblyopia developed at or after 5 years of age. • Only 3 of the 16 participants with amblyopia that was unresolved by 5 years of age (18.8%) perceived the McGurk effect (adjusted odds ratio, 27.0 [95% CI, 1.1-654.0]; P = .02).

9. Results Timeline of Amblyopic Children and Their Perceptions of the McGurk Effect

10. Comment • Children with a history of amblyopia exhibit impaired visual-auditory integration and perceive speech differently, even when binocularly viewing a stimulus with a nonamblyopic eye with visual acuity of 20/20. • Early childhood appears to serve as an approximate point for the development of successful visual-auditory fusion, by which time amblyopia must have either resolved or begun. • Studies have demonstrated that children with language learning impairment and autism spectrum disorders also fail to perceive the McGurk effect. These studies did not assess visual acuity in each eye; hence, monocular amblyopic patients may have been included in the studies, possibly confounding their results. The current study contributes to the literature by demonstrating how amblyopia itself can influence the perception of sound.

11. Comment • Limitations: • Small sample size. • Retrospective determination of onset of amblyopia through chart review. • Recall bias owing to follow-up visits scheduled based on clinical need. • Arbitrary cutoff of 5 years to determine onset or resolution of amblyopia. Five years of age was chosen because most patients were recruited between 4 and 6 years of age during preschool vision screenings. • Lack of required formal audiological testing. However, patients were excluded if they failed to correctly perceive audio-only stimuli /pa/ and /ka/ (ie, with the visual track as a blank screen). • No standardized tests for grammatical understanding or intelligence.

12. Contact Information • If you have questions, please contact the corresponding author: • Rajen U. Desai, MD, Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, 645 N Michigan Ave, Ste 440, Chicago, IL 60611 (rajen-desai@md.northwestern.edu). Funding/Support • Dr Desai is supported by the Heed Ophthalmic Foundation and the Society of Heed Fellows. The design and conduct of the study were supported by grants from the Knights Templar Eye Foundation Inc and Research to Prevent Blindness. Conflict of Interest Disclosures • None reported.