ABSTRACT
Glaucoma is a disease that is chronic in nature and indistinctive at an early stage, leading to late
detection. It has become a major public health problem and a leading cause of irreversible
blindness worldwide. The proton magnetic resonance spectroscopy (1H-MRS), of late, has been
utilised to evaluate metabolites concentration in the brain, especially for detecting
neurodegenerative disease. Considering that glaucoma is a neurodegenerative disease, studies on
the concentration of metabolites using 1H-MRS in glaucoma patients could be investigated. This
scoping review aims to examine the extent, range, and nature of studies on the 1H-MRS technique
in glaucoma disease. The literature search was conducted using MEDLINE, CINAHL and
SCOPUS, dated from 2000 until 2019. Studies on glaucoma using 1H-MRS were considered. Any
processing method used to characterise the metabolite concentration generated by the 1H-MRS
protocol has also been considered. Nine full-text studies were yielded after hundreds of literature
identification, screening, and eligibility assessment. The included studies sought to determine the
feasibility, change, and comparability of metabolite concentrations in glaucoma patients using 1HMRS with more studies utilising single-voxel spectroscopy (SVS) technique. The chosen anatomy
of interest could have been influenced by several criteria, including the association between
anatomy and the research query and the volume-sizing capabilities of the 1H-MRS technique. Six
(6) metabolites were significantly identified, and quantified, including N-acetyl aspartate,
Creatine, Choline, Myo-Inositol, Lactate and Glutamate-Glutamine. This scoping review points
out the 1H-MRS application in different types and severity of glaucoma, highlighting the
information on the type of patients, the detected metabolites in the anatomy involved, the 1H-MRS
technique used and the raw data decipherment processing software. Future studies are needed to
validate existing glaucoma studies and to explore the potential of detecting incipient glaucoma.
Introduction: Short-term fasting may influence intraocular pressure (IOP) due to alteration of fluid (total body water;
TBW, and water intake) and fat (total body fat; TBF). This study aimed: i) to compare IOP values within and between,
fasting and non-fasting periods; and ii) to assess the association between IOP and, TBW and TBF. Methods: Thirty
healthy participants aged 21.8±1.1 years were assessed on two different periods (fasting vs. non-fasting). During each
period, the IOP, TBW and TBF values were assessed for four times (morning, afternoon, evening, late-evening). The
IOP was measured using AccuPen® tonopen, while TBW and TBF were assessed by using a Tanita body composition
analyser. Results: During fasting, the IOP value in the afternoon (14.53±2.33 mmHg) was significantly higher than in
the evening (12.43±2.73 mmHg, p=0.009) and late-evening (12.60±2.44 mmHg, p=0.003). No significant difference
in IOP was observed during non-fasting period. The mean of IOP in the evening was significantly lower during fasting
compared to non-fasting (12.43±2.73 mmHg vs 13.75±2.53 mmHg, p=0.044). The IOP and TBW were negatively
correlated (r=-0.268; p=0.011) during non-fasting and showed no association during fasting period. There was no
significant correlation between IOP and TBF during both fasting and non-fasting periods. Conclusion: IOP reduction
during short-term fasting, together with the no association with TBF and TBW suggested that IOP is an independent
factor that reduces during fasting in healthy population.