Defining the structure - function horizontal meridian of the human macula

Lemor, Daniel (2015). Defining the structure - function horizontal meridian of the human macula MPhil Thesis, School of Medicine, The University of Queensland. doi:10.14264/uql.2015.383

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Author Lemor, Daniel
Thesis Title Defining the structure - function horizontal meridian of the human macula
School, Centre or Institute School of Medicine
Institution The University of Queensland
DOI 10.14264/uql.2015.383
Publication date 2015-03-02
Thesis type MPhil Thesis
Open Access Status Other
Supervisor Jonathan Nussdorf
Glen Gole
Total pages 37
Language eng
Subjects 1113 Ophthalmology and Optometry
Formatted abstract
Purpose: To investigate the congruency of the retinal ganglion cell structure – function relationship in the macular region of human subjects who manifest horizontal split fixation due to glaucoma. Subjects with glaucoma who manifest asymmetric loss of retinal ganglion cells across the horizontal meridian macula were examined using structural measures provided by spectral domain optical coherence tomography (SD-OCT) and functional measures using automated visual field perimetry (HVF). Using this data, the horizontal meridian of the human macula was defined using structure – function linking analysis of retinal ganglion cell integrity.

Methods: 26 stable glaucoma subjects who manifest split fixation on HVF 24-2 S/S testing were identified and performed Heidelberg Spectralis® SD-OCT posterior pole asymmetry analyses. The posterior pole asymmetry analysis image was oriented in a systematic manner so that the macular thickness grid was centered on the fovea and its horizontal meridian intersected the optic nerve head at five pre-selected equidistant locations along the central vertical axis. The posterior pole asymmetry analysis for each optic nerve head intercept generated average superior and inferior retinal hemifield and temporal quadrant thicknesses and the superior to inferior thickness ratio calculated.

Results: The subjects had a Humphrey Visual Field 24-2 SITA Standard (HVF S/S) average Mean Defect = 7.43 (SD = 4.58) and an average Pattern Standard Deviation = 9.60 (SD = 2.77). A one-way repeated measures ANOVA demonstrates a significant difference between the optic nerve head intercept locations for the hemifield ratios [F(4, 26)=19.37, p<.0001], as well as for the temporal quadrant ratios [F(4,16)=13.3, p <.0001]. Tukey post-hoc pairwise comparisons of the hemifield and quadrant thickness ratios demonstrate a significant difference between the superior and inferior poles (p<.01). The SD-OCT thickness ratios for both the hemifield and temporal quadrants increase as the horizontal meridian migrates towards the inferior pole of the optic nerve head.

Conclusions: We demonstrate that in order to maximize the hemifield ratio and the congruency of the macular structure - function relationship in subjects with glaucoma, the horizontal meridian of the posterior pole asymmetry grid should intersect the optic nerve head near the inferior pole. This is in contradistinction to the conventional practice of placing the horizontal median through the geometric center of the optic nerve head.
Keyword Glaucoma
Retinal thickness
OCT
Structure - function
macula
Retinal ganglion cell
Visual field

Document type: Thesis
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Created: Thu, 26 Feb 2015, 08:40:42 EST by Daniel Lemor on behalf of Scholarly Communication and Digitisation Service