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Neural Engineering

Neural Engineering - Poster Session D

Poster Z16 - Accommodative Cue Interactions within Convergent Maddox Components of Vergence Responses of Binocularly Normal Controls

Friday, October 25, 2024
3:30 PM - 4:30 PM EST
Location: Exhibit Hall E, F & G

Introduction:  In daily life, the coordinated rotation of the eyes (vergence) and modulation of each intraocular lens (accommodation) allow for visual stimuli to be viewed singularly and acutely. Whether rotating your eyes inward (convergence) to look at-near, or outward (divergence) at-far, three primary visual cues provide the brain with information to appropriately accommodate and binocularly coordinate the eyes: disparity (D); the binocular difference in light cast onto the retina, blur (B); the monocular acuity of a stimulus, and proximity (P); the monocularly perceived visual distance of a stimulus based on apparent size. While the contributions of the Maddox cues have been studied at static visual ranges with varying accommodative demands, the dynamic contributions of each of these visual cues in combination and isolation lacks investigation. Henceforth, understanding the dynamic contributions to selectively presented combinatory and isolated visual cues in a novel haploscope configuration within binocularly normal control (BNC) participants can provide a baseline of comparison and insight into the interplay of isolated, paired, and all-visual cues present conditions. Protocol approval was provided by the New Jersey Institute of Technology Institutional Review Board (HHS FWA 00003246) in accordance with the Declaration of Helsinki. Prior to enrollment, all participants provided written informed consent.

Materials and

Methods:  This investigation is a component of the Convergence Insufficiency Neuro-mechanism Adult Population Study (CINAPS) registered on ClinicalTrials.gov (NCT03593031). Complete eligibility criteria are referenced from Table 1 of the CINAPS study design. Near-point of convergence and amplitude of accommodation were measured using an Astron ACR/21 slide ruler with age-normal accommodative amplitudes calculated referencing Hofstetter’s formula. The experimental haploscope is showcased in Figure 1, the independent stimuli monitors at visually-near (40cm) and visually-far (100cm) with a PlusOptix PowerRef 3 dynamic autorefractor recording at 50Hz, positioned optically at 1 meter, allow for accommodative and gaze (vergence eye position) recording. The Accommodative Analysis Movement Program (AMAP) was utilized to identically process all recordings and is complemented by the statistical software Jamovi for resultant analyses. Binocular data were recorded for stimulations regardless of stimuli presentation. Further shown in Figure 1, the stimuli and presentation selected invokes varying visual cues: a high-acuity Maltese cross stimulates accommodation (B), which can be diminished (-b) utilizing a low-acuity Gabor Patch, binocular stimuli presentation will invoke a disparity (D) response, that can be diminished (-d) by monocular stimuli presentation, and by fixing a stimuli’s size proximity (P) cueing occurs due to visual stimuli size changes, which can be diminished (-p) by scaling the stimuli to appear equal in size at visual near and far.

Results, Conclusions, and Discussions: Thirty-one participants were enrolled, recordings which contained significant data were omitted. A total of 20 BDP2, 22 BD(-p), 27 BP(-d), 29 DP(-b), 24 B(-dp), 31 D(-bp), and 29 P(-bd) participant-level cue response datasets were analyzed. Non-parametric Welch’s One-Way ANOVAs with Games-Howell post-hoc analysis were performed following failure (p < 0.05) of Levene’s test for homogenous variance. Main effect interactions for isolated-cue contributions: Peak Velocity (PV) [F(2,43.3)=37.6, p< 0.001], Response Amplitude (RA) [F(2,46.5)=93.1, p< 0.001], and Final Amplitude (FA) [F(2,46.2)=97.6, p< 0.001] with post-hoc results provided in Table 1.
Isolated-cues compared to paired-cues: PV [F(5,64.8)=35.7, p< 0.001], RA [F(5,67.0)=83.7, p< 0.001], and FA [F(5,66.7)=109.4, p< 0.001] with post-hocs summarized in Table 2.
Isolated-cues compared to all-cue conditions: PV [F(3,47.7)=58.6, p< 0.001], RA [F(3,49.8)=112.6, p< 0.001], and FA [F(3,49.1)=132.8, p< 0.001] with post-hocs depicted in Table 3.
All-cues compared to paired-cues: PV [F(3,47.7)=13.6, p< 0.001], RA [F(3,48.6)=15.8, p< 0.001], and FA [F(3,49.1)=24.0, p< 0.001] with post-hoc evaluations shown in Table 4.
The blur and disparity cues significantly contributes to the overall accommodative response. While the disparity cue failed to maintain sustained final accommodative amplitude compared to blur, this behavior is similar to prior literature. The proximal cue contributes minimally to overall accommodation in isolation and combination. Understanding the interconnectivity of accommodation and convergence eye movements through convergence accommodation / convergence (CA/C) cross-linking in binocularly normal controls provides a growing comparison to further enable investigations into how potential disruptions of these pathways occur in common binocular vision dysfunctions such as convergence insufficiency (CI), where the comorbidity of accommodative dysfunctions is prevalent.

Acknowledgements (Optional):  This study was supported by the National Eye Institute of the National Institutes of Health as a part of the CINAPS (NEI R01EY023261) to T.L.A.