June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Fixation Eye Movement Abnormalities, Stereopsis and Inter-ocular suppresion in Amblyopia.
Author Affiliations & Notes
  • Fatema Firoz Ghasia
    Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
    Director of Visual Neurosciences and Ocular Motility Lab, Cleveland Clinic, Cleveland, Ohio, United States
  • Cody Dulaney
    Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
  • Jordan Murray
    Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
  • Footnotes
    Commercial Relationships   Fatema Ghasia None; Cody Dulaney None; Jordan Murray None
  • Footnotes
    Support  This study was supported in part by Research to Prevent Blindness Amblyopia Disney Research Award (FG), CWRT CTSC Pilot Grant Program (FG), Cleveland Clinic RPC Grant (FG), Lerner Research Institute Artificial Intelligence in Medicine (FG), Case Western Reserve University Biomedical Research Fellowship- Hartwell Foundation (CD), NEI T32: 5 T32 EY 24236-4 (JM), the NIH-NEI P30 Core Grant (IP30EY025585), Unrestricted Grants from The Research to Prevent Blindness, Inc., and Cleveland Eye Bank Foundation awarded to the Cole Eye Institute.
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 2285. doi:
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      Fatema Firoz Ghasia, Cody Dulaney, Jordan Murray; Fixation Eye Movement Abnormalities, Stereopsis and Inter-ocular suppresion in Amblyopia.. Invest. Ophthalmol. Vis. Sci. 2022;63(7):2285.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose : Amblyopic patients are known to have fixation instability, which arises from alteration of physiologic fixation eye movements (FEMs) and nystagmus. The purpose of the study is to examine the association between amblyopia type and FEM abnormalities on stereopsis and inter-ocular suppression.

Methods : We recruited 34 amblyopes (anisometropic=14, strabismic=12,mixed=8) and 7 controls. Eye movements were recorded using infrared video-oculography during a) Fellow eye viewing(FEV), b) Amblyopic eye viewing(AEV) c) Both eye viewing(BEV), and d) Dichoptic viewing(DcV) at varying FE contrasts. Subjects were classified as having either no nystagmus(n=15), fusion maldevelopment nystagmus (FMN)(n=7), and patients with nystagmus without any structural anomalies that do not meet the criteria of FMN and infantile nystagmus(n=12). An adaptive staircase method was used to measure visual acuities during FEV, AEV and BEV and inter-ocular suppression using Dichoptic Motion Coherence(DMC). The threshold of inter-ocular suppression was determined by the number of dots required to correctly identify the motion coherence at a given FE contrast and area under the curve was computed. Stereoacuity was measured with the Titmus fly test.

Results : Increased fixation instability was associated with greater stereopsis and inter-ocular suppression deficits. Stereopsis deficits were greatest in patients with FMN (Controls: 1.6±0, None:2.1±0.25,Nystagmus no FMN:3.1±0.92, FMN:3.3±0.92,ANOVAp<0.005) and patients with mixed amblyopia(Controls: 1.6±0,Anisometropic:2.1±0.25,Strabismic: 3.1±0.92, Mixed:3.3±0.92,ANOVAp<0.005). AUC for DMC thresholds was greater in amblyopia than controls while controlling for visual acuity deficits. (Controls:415.6± 275.9, Amblyopia:1094.3±884, #ofdots x contrast level, p <0.04). The suppression deficits were dependent on AE visual acuity deficit (p=0.003 and p=0.014) with no significance noted as a function of amblyopia type or FEM abnormalities (p=0.87, p=0.74 respectively).

Conclusions : Neurophysiologic studies have shown that horizontal binocular connections in MT/MST are critical for emergence of stereopsis. Lack of binocular connections in MT/MST drives the development of FMN. We have found that the presence of FMN was associated with greater stereopsis deficits whereas the extent of suppression is primarily driven by severity of amblyopia.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.


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