EVALUATION OF OPTIC NERVE HEAD FUNCTIONS AND TOPOGRAPHY AFTER AN EPISODE OF OPTIC NEURITIS
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Date
2011
Authors
CHUA, CHUI YIN
Journal Title
Journal ISSN
Volume Title
Publisher
Pusat Pengajian Sains Perubatan Universiti Sains Malaysia
Abstract
Introduction
The retinal nerve fiber layer (RNFL) is the only part of central nervous system where
unmyelinated axons can be visualized. Role of Heidelberg Retinal Tomography III (HRT III)
in the measurement of RNFL thickness and other optic nerve head topography in non
glaucomatous optic neuropathies is still inconclusive.
Objectives
To compare optic nerve functions and parameters between optic neuritis and healthy control
eyes, and to correlate the mean optic nerve functions and parameters in optic neuritis.
Methodology
28 subjects with history of single episode of optic neuritis and 28 age and sex-matched
controls underwent a complete ocular examination including visual acuity, contrast
sensitivity, colour vision and optic nerve head measurement with HRT III. The mean optic
nerve functions and parameters were compared between the groups using T test. The
relationship between optic nerve functions and parameters in optic neuritis were evaluated
using multiple linear regression. Pearson’s correlation was used to determine the correlation
between the optic nerve functions and parameters.
Results
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There was significant reduction in global optic nerve functions in the optic neuritis group (p
< 0.05). In the optic neuritis group, the mean optic nerve head parameters showed significant
RNFL thinning (p < 0.001) and neuroretinal rim volume reduction (p =0.0065). There was
also significant increase in the cup shape (p = 0.0005), cup-disc area ratio (p = 0.0093) and
optic cup area (p = 0.0300). Significant and good correlations were evident between the mean
RNFL thickness and all optic nerve functions, with particularly strongest correlation with
contrast sensitivity at high spatial frequency (r = 0.7351, p < 0.001). There was also
significant but fair correlation between the cup shape and contrast sensitivity (r= -0.4463, p =
0.016).
Conclusions
There was significant global reduction of mean optic nerve functions in the optic neuritis
group. In this group, the mean optic nerve parameters were also significantly affected, in
particularly RNFL thickness, neuroretinal rim volume, cup shape and cup disc area ratio. The
correlation between the mean RNFL thickness and optic nerve functions was significant and
good, in particular the contrast sensitivity.
Description
Keywords
Ophthalmology