The relationship between fusion, suppression, and diplopia in amblyopia

Daniel P. Spiegel, Alex S. Baldwin, Mark A. Georgeson, Reza P. Farivar, Robert F. Hess

Research output: Contribution to journalConference abstract

Abstract

Purpose: Traditionally, it has been thought that no binocular combination occurs in amblyopia. However, there is a growing body of evidence that there are intact binocular mechanisms in amblyopia rendered inactive under normal viewing conditions due to imbalanced monocular inputs. Georgeson and Wallis (2014) recently introduced a novel method to investigate fusion, suppression and diplopia in normal population. We have modified this method to assess binocular interactions in amblyopia.

Methods: Ten amblyopic and ten control subjects viewed briefly-presented (200 ms) pairs of dichoptically separated horizontal Gaussian blurred edges. Subjects reported one central edge, one offset edge, or a double edge as the vertical disparity was manipulated. The experiment was conducted at a range of spatial scales (blur widths of 4, 8, 16, and 32 arc min) and contrasts. Our model, based Georgeson and Wallis (2014), converted subjects’ responses into probabilities of fusion, suppression, and diplopia.

Results: When the normal participants were presented equal contrast to each eye the probability of fusion gradually decreased with increasing disparity, as the probability of diplopia gradually increased. In only a small proportion of the trials, normal participants experienced suppression. The pattern was consistent across all edge blurs. Interestingly, the majority of amblyopes had a comparable pattern of fusion, i.e. decreasing probability with increasing disparity. However, with increasing disparity the amblyopes tended to suppress the amblyopic eye, experiencing diplopia only in a small proportion of trials particularly at large blurs. Increasing the interocular contrast offset favouring the amblyopic eye normalized the pattern of data in a way similar to normal participants. There were some interesting exceptions: strong suppressors for which our contrast range was inadequate and one case in which diplopia dominated.

Conclusions: This task is suitable for assessing binocular interactions in amblyopic participants and providing a way to quantify the relationship between fusion, suppression and diplopia. In agreement with previous studies, our data indicate the presence of binocular mechanisms in amblyopia. A contrast offset favouring the amblyopic eye normalizes the measured binocular interactions in the amblyopic visual system.

Original languageEnglish
Article number2196
Number of pages1
JournalInvestigative Ophthalmology and Visual Science
Volume56
Issue number7
Publication statusPublished - 30 Jun 2015
EventARVO 2015 Annual Meeting : Powerful Connections: Vision Research and Online Networking - Colorado Convention Center (CCC), Denver, CO, United States
Duration: 2 May 20157 May 2015

Bibliographical note

ARVO 2015 Annual Meeting : Powerful Connections: Vision Research and Online Networking, 2-7 May 2015, Denver, CO, United States.

Fingerprint Dive into the research topics of 'The relationship between fusion, suppression, and diplopia in amblyopia'. Together they form a unique fingerprint.

  • Research Output

    • 7 Meeting abstract

    Accommodative response to electrical stimulation of the sclera of peripheral cornea in cats and porcines

    Mihashi, T., Hirohara, Y., Miyoshi, T., Miyagawa, S., Kanda, H., Sawai, H., Fujikado, T., Drew, T. & Wolffsohn, J. S., Jun 2015, In : Investigative Ophthalmology and Visual Science. 56, 7, p. 6005 1 p.

    Research output: Contribution to journalConference abstract

    Open Access
  • Can aberrometry provide rapid and reliable measures of subjective depth of focus following multifocal intraocular lens implantation?

    Applegate, R. A., Dhallu, S. K., Sheppard, A. L., Mihashi, T., Drew, T. E., Shah, S. & Wolffsohn, J. S., Jun 2015, In : Investigative Ophthalmology and Visual Science. 56, 7, p. 2979 1 p.

    Research output: Contribution to journalConference abstract

    Open Access
  • Ciliary muscle morphology in emmetropia and ocular biometric correlates

    Saigal, R., Davies, L. N. & Sheppard, A. L., 30 Jun 2015, In : Investigative Ophthalmology and Visual Science. 56, 7, p. 5997 1 p.

    Research output: Contribution to journalConference abstract

    Open Access
  • Cite this