Glaucoma encompasses various conditions, including progressive optic nerve damage marked by excavation of the optic disc (cupping). Globally, it is a primary cause of permanent blindness (1). Primary open-angle glaucoma (POAG) is prevalent and has a multifaceted origin. Typically, glaucoma remains symptom-free during its early stages, and the sole established method to impede its progression is to lower intraocular pressure (IOP), which can be achieved using medicinal, laser, or surgical procedures (2). The primary risk factors for POAG include older age, heightened intraocular pressure, sub-Saharan African ancestry, familial history, and significant myopia. Moreover, advanced age, hyperopia, and East Asian descent are the primary risk factors associated with primary angle-closure glaucoma (PACG)(3).
The risk of glaucoma increases with age and is often intertwined with other age-related conditions such as macular degeneration, vascular diseases, and obstructive sleep apnea (4). Although these associations exist, they do not create direct links between most age-related diseases and glaucoma. Studies, such as the Ocular Hypertension Treatment Study, suggest that male sex might predict the onset of POAG(5). However, the influence of sex on the incidence of glaucoma varies according to its definition. While some studies have indicated a greater risk for angle-closure glaucoma in women, there is no clear sex inclination for patients with open-angle glaucoma. Notably, women's longer life expectancy increases their susceptibility to glaucoma and eventually, glaucoma-related vision loss (6).
In recent years, there has been a growing global occurrence of myopia. The link between myopia and POAG is widely acknowledged. Extensive studies involving large populations have consistently shown an increase in POAG rates with increasing myopia. Moreover, this connection appears notably stronger in patients with severe myopia (7). Individuals with myopia commonly exhibit reduced retinal nerve fiber layer initially (8).
Optical correction methods, such as glasses, contact lenses, and refractive surgery, can address myopia. However, this condition is associated with potential complications, such as myopic macular degeneration, retinal detachment, cataracts, and open-angle glaucoma. These complications pose a risk of permanent vision loss in the later stages of life (9,10). In patients with mild-to-moderate myopia, in which the axial length is less than 26.5 mm, the size of the optic disc remains comparable to that in nonmyopic eyes (6).
Photographs aid in tracking optic disc changes, whereas optical coherence tomography (OCT) has transformed glaucoma monitoring capabilities. OCT, a noninvasive imaging method that uses Michelson interferometry, decodes light interference patterns from intraocular tissues. It quantitatively measures the optic nerve, the retinal ganglion cell axon layer (retinal nerve fiber layer), and ganglion cell body layer (11,12). These structural changes, such as thinning of the retinal nerve fiber layer, often precede functional losses that are detectable by standard visual field tests (1).
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The current study aimed to analyze the interrelationship and association between myopia and glaucoma, along with identifying the associated risk factors and structural and functional findings that could assist in effectively monitoring these conditions. We mainly focused on the ganglion cell complex (GCC) and retinal nerve fiber layer (RNFL) and their roles in detecting glaucoma in patients with myopia. The examination of the GCC layer is more sensitive than that of the circumpapillary RNFL (pRNFL). The pRNFL is the most commonly used parameter for evaluating glaucoma. In ganglion cells, the primary segment affected is the inner plexiform layer, followed by the macular retinal nerve fiber layer (mRNFL) and ganglion cell layers. We also discuss the association between IOP and axial length.