Ng, Seok Hui
(2016)
Evaluation of visual electrophysiological test in obstructive sleep apnoea.
Masters thesis, Universiti Sains Malaysia.
Abstract
Introduction
Obstructive sleep apnea (OSA) is a life-threatening, sleep-related breathing disorder
characterized by partial (hypopneas) and complete pauses (apneas) in breathing that
last at least 10 seconds during sleep. As a consequence, the blood oxygen saturation
may fall, with resulting in a hypoxia state. OSA has been associated with ocular
conditions such as non-arteritic anterior ischemic optic neuropathy (NAION),
papilloedema, glaucoma and central retinal vein occlusion. Visual
electrophysiological tests like pattern visual evoked potential (PVEP) and pattern
electroretinogram (PERG) may be able to detect functional impairment of the retina
and visual pathway in OSA patients.
Objective
To compare the PVEP & PERG changes in patients with OSA and control group. We
also analyzed the relationship between visual electrophysiological tests with the
severity of OSA.
Material and methods
A comparative cross-sectional study was conducted in Hospital Universiti Sains
Malaysia involving 40 samples of OSA patients and 31 control subjects. A complete
ocular examination was performed which include visual acuity, anterior and posterior
segment. PERG (0.8⁰ checks size) and PVEP (0.25⁰ checks size) were conducted bya single technician. Independent t-test, Mann-Whitney, Kruskal-Wallis Test, Pearson
and Spearman‘s correlation test were used in statistical analysis.
Results
There were statistically significant reduction of the PVEP P100 wave amplitude
(P<0.001) and delay in PVEP P100 and N75 latency (P<0.001) in the OSA group.
Among OSA patients, we also observed a significant reduction of the P50 wave
amplitude (P<0.001) in PERG, compared to the control group. However, there is no
finding on association of PVEP and PERG according to severity of OSA . There was
no significant differences of PERG latency were observed in either group. There was
no significant correlation in PVEP or PERG between OSA patients with different
disease severity except PVEP latency N75 which is statistically significant but fair
negative correlation
Conclusion
OSA patients have significant abnormalities in VEP amplitude and latency, and ERG
amplitude, suggesting that hypoxia may be a pathophysiology in these conditions.
There were no significant relationships between PVEP and PERG in AHI of OSA
patients
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