Dietary patterns and testosterone balance: a review of clinical data and perspectives.

Optical coherence tomography (OCT) is a critical diagnostic test for detecting and monitoring glaucoma. It is a non-invasive, high-resolution imaging modality that quantitatively assesses the neural structures implicated in the disease process. In glaucoma management, OCT is often used to image the optic nerve head and measure the thickness of the circumpapillary retinal nerve fiber layer (cpRNFL). Since structural glaucomatous changes often occur before functional changes can be detected with visual field (VF) testing, thinning of the cpRNFL may reflect axonal loss and can be an early indicator of glaucomatous damage or progression. Within the past decade, there has also been significant interest in using OCT to image the macula and measure the macular ganglion cell-inner plexiform layer (mGCIPL) thickness. The macula is a region that contains the highest density of retinal ganglion cells, and it can also be affected in early glaucoma. Glaucoma suspects who have faster rates of mGCIPL thinning have been shown to have a higher risk of developing VF changes. Moreover, mGCIPL measures are at least as accurate as cpRNFL measures in predicting VF progression in early glaucoma. Another appeal of mGCIPL analysis is that it may be able to detect structural changes in later stages of disease when cpRNFL analysis is no longer sensitive to further structural changes. The macular region contains over 50% of all the retinal ganglion cell bodies in the retina. Meanwhile, the cpRNFL is composed almost entirely of axons of the retinal ganglion cells. Prior work has shown that axonal degeneration may precede retinal ganglion cell soma loss in glaucomatous optic neuropathy. Although retinal ganglion cell damage in the macular region can also occur in early glaucoma, the mGCIPL may be more likely to maintain its thickness in later stages of disease than the cpRNFL due to the larger concentration of retinal ganglion cell bodies in the macular region. Prior studies investigating the association between mGCIPL thinning and glaucoma have mostly focused on demonstrating its utility in diagnosing the presence of the disease. Knowing the rates of mGCIPL thinning in patients who develop VF progression would be helpful for glaucoma management in terms of disease monitoring as it relates to deciding whether therapeutic escalation is needed. The studies reporting the rates of mGCIPL thinning in those with VF progression are limited to early-stage glaucoma, such as those with pre-perimetric disease. Although some studies report the rates of mGCIPL thinning in later stages of glaucoma, the sample sizes are modest, and some do not distinguish between the rates of those with VF progression and those without progression. It would also be beneficial to know the rates of cpRNFL thinning compared to rates of mGCIPL thinning in those who develop VF progression to assess the utility of the two measures at clinically meaningful outcomes. Since mGCIPL thickness may be more likely to be maintained in later-stage glaucoma and more retinal tissue remains above the measurement floor, this may allow mGCIPL to better detect changes in advanced disease than cpRNFL. Thus, it would be helpful to know the rates of cpRNFL vs. mGCIPL thinning at different stages of disease severity. To date, studies comparing rates of cpRNFL thinning and mGCIPL thinning in glaucoma progression are limited by modest sample sizes, focus primarily on a single stage of disease (early glaucoma or advanced glaucoma), or do not differentiate stages of disease severity. Our study aims to quantify the rates of cpRNFL and mGCIPL thinning in a large clinical population of glaucoma patients who develop VF progression and compare the rates of thinning to those who do not develop VF progression. Our study also aims to assess the rates of cpRNFL and mGCIPL thinning across a broad range of glaucoma severity. Our goal is to determine which structural measure is more associated with progression at each stage of glaucoma to help clinicians optimize disease monitoring in patient populations with varying disease severity and improve earlier detection of progression.