Advanced glycation end products as a biomarker for accelerated ocular ageing and glaucoma
MetadataShow full item record
Advanced glycation end products (AGEs) have a large impact on the healthy ageing population and those diagnosed with pathology. Studies have linked AGEs to glaucomatous optic neuropathy, however there is little consensus on the role AGEs play in glaucoma development. Furthermore, it is known that diet is an exogenous source of AGEs, however it is not clear how dietary AGE (dAGE) influences tissue-bound levels in the body. The overarching theme of this thesis was to assess the impact of AGE level, measured both through diet and tissue-bound levels in the skin (skin autofluoresence, SAF), on retinal vessels and the cornea in healthy participants and patients diagnosed with ocular hypertension (OHT), early stage normal-tension glaucoma (NTG) and early stage primary open angle glaucoma (POAG).
A UK-specific food frequency questionnaire (FFQ) was developed and found to reliable and valid. This newly designed FFQ was subsequently used throughout the thesis to measure dAGE. In healthy controls, the contribution of dAGE to tissue-bound AGE levels appeared to be minimal. The level of AGE taken in via diet was similar between healthy, OHT, NTG and POAG participants.
Interestingly, tissue-bound AGE level (SAF) was found to be 16% higher in NTG and 14% higher in POAG than healthy control participants. Adding to the evidence that SAF, as an accessible measure, may be a suitable long-term biomarker of glaucoma.
Higher SAF was associated with narrower retinal arteries (CRAE) in a healthy population, adding to the evidence that AGEs may be an accessible marker of vascular health. The NTG group had a significantly narrower CRAE than healthy controls as well as the highest SAF level. Increased SAF was also associated with a less viscoelastic, stiffer cornea in the NTG group only. These findings pose interesting questions about the possible association of SAF with ocular rigidity and subsequent increased susceptibility to IOP or arterial blood supply related injury, however larger scale studies are needed before any conclusions could be drawn.