Development of a novel gaze-contingent perimeter and assessment of retinal structure in infantile nystagmus

Thomas, Nikita 2020. Development of a novel gaze-contingent perimeter and assessment of retinal structure in infantile nystagmus. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Standard automated perimetry (SAP) is the current gold-standard for detecting and monitoring glaucomatous visual field loss. However, SAP may be unreliable in patients with infantile nystagmus (IN) as this method depends on stable fixation as a prerequisite to achieving reliable visual field outcomes. Microperimetry is a relatively recent method that aims to overcome this issue in patients with unstable fixation by combining retinal imaging with visual field assessment. However, most commercial microperimeters are only partially gaze-contingent (PGC): the stimulus is initially presented in the appropriate retinal location, but stimulus position is not updated to compensate for eye movements made during stimulus presentation. To overcome these inadequacies for visual field examination in IN, a novel gaze-contingent perimeter was designed, which incorporates gaze-contingency that continuously compensates for eye movements before and during a stimulus presentation (continuous gaze-contingency [CGC]). In the first study described in this thesis, the test-retest variability of CGC in healthy observers was shown to be equivalent to that of PGC and no gaze-contingency (NoGC). The second study demonstrated that CGC is superior to PGC and NoGC at detecting physiological visual field loss (the optic nerve head) in IN. The third study introduced optical coherence tomography (SD OCT), in which foveal images were obtained in individuals with IN in order to assess foveal pit diameter horizontally and vertically. The results indicate that foveal pit diameter is elongated horizontally in idiopathic IN, providing potential compelling evidence towards to the concept of foveal plasticity in early infancy. The final study combines CGC with SD-OCT imaging in order to investigate structural and functional relationships. The results show that CGC thresholds can significantly predict retinal layer thicknesses in IN. The next step for future studies is to investigate the ability of CGC to detect pathological visual field loss in patients with IN.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Optometry and Vision Sciences
Subjects:	R Medicine > RE Ophthalmology
Uncontrolled Keywords:	infantile nystagmus, perimetry, microperimetry, gaze-contingency, visual field, optical coherence tomography, fovea, retina
Date of First Compliant Deposit:	27 May 2021
Last Modified:	04 Aug 2022 02:13
URI:	https://orca.cardiff.ac.uk/id/eprint/141597

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