Early Glaucoma Detection: Challenges and Solutions
Glaucoma’s silent progression highlights a challenge we all face as clinicians. Millions of individuals remain at risk for irreversible vision loss due to undiagnosed disease – 50% or more of all cases. This emphasizes our responsibility to enhance early detection strategies for this sight-threatening condition.
Existing clinical, structural, and functional tests depend on both baseline exams and the need to observe changes over time, delaying the assessment of treatment effectiveness and the identification of rapid progression.
In this article, we will consolidate our knowledge as eye care professionals about Glaucoma, explore current clinical detection practices, and discuss potential areas to optimize early detection.
What We Know about Glaucoma
Glaucoma is a complex neurodegeneration fundamentally linked to changes occurring in two locations: the anterior eye (elevated pressure) and the posterior eye (optic neuropathy). Factors influencing glaucoma development include:
Early stages of Glaucoma are often asymptomatic, highlighting the importance of comprehensive eye exams, even without apparent vision issues. Current diagnostic criteria are insufficient and lack markers of early disease.
Glaucoma is broadly divided into primary and secondary types, with?primary open-angle Glaucoma (POAG)?representing approximately?three-quarters (74%)?of all glaucoma cases.?
Primary glaucomas develop independently of other eye conditions, while secondary glaucomas arise as a complication of various eye diseases, injuries, or medications.
POAG is characterized by an open iridocorneal angle, IOP usually > 21 mmHg, and optic neuropathy. Risk factors include age (over 50), African ancestry, and elevated IOP. While IOP is a significant factor, it’s unpredictable – some patients with high IOP don’t develop Glaucoma, and some glaucoma progresses even at normal IOP.
Normal-tension Glaucoma (NTG)?shares POAG’s optic nerve degeneration but with consistently normal IOP levels (<21mmHg). Vascular dysregulation and low blood pressure are risk factors. While rarer than POAG, IOP lowering can still be beneficial.
Primary Angle-Closure Glaucoma?(PACG) is caused by narrowing the iridocorneal angle, blocking aqueous humor flow. More common in East Asian populations, it can be acute (severe symptoms, IOP often > 30mmHg) or chronic.
The most effective way to get information about nerve states is OCT, which allows us to penetrate deep into the layers to see the nerve fiber layer separately, making it possible to assess the extent of damage and thinning to this layer in much more detail.?
Secondary glaucomas?are caused by underlying conditions that elevate IOP. Examples include pseudoexfoliative, neovascular, pigmentary, and steroid-induced Glaucoma.
Age is a central risk factor for glaucoma progression, linked to cellular senescence, oxidative stress, and reduced resilience in retinal ganglion cells and the trabecular meshwork. Intraocular pressure (IOP) remains the most significant modifiable risk factor. Understanding individual susceptibility to IOP-related damage is crucial. Existing IOP-lowering treatments have limitations in both efficacy and side effects.
领英推荐
Vision Field Test for Glaucoma Detection
As the optic nerve transmits visual information from the retina to the brain and each part of the retina transmits data via a corresponding set of fibers within the optic nerve, damage to specific nerve fibers results in loss of the associated portion of the visual field.
Challenges with this test include its complexity, especially for older patients, and its subjective nature.
Changes in the visual field determine glaucoma severity. These changes indicate how much of the visual field is already damaged and which parts of the optic nerve are compromised. We call these ‘functional changes‘ as they directly impact visual function.
Fundus Photo for Glaucoma Detection
Alongside functional changes, Glaucoma causes visible?structural changes?in the optic nerve that can be observed during a fundus examination. The optic nerve begins at a point on the retina where all the nerve fibers gather, forming the optic disc (or optic nerve head). The nerve fibers are thickest near the optic disc, creating a depression or ‘hole’ within it.
As Glaucoma progresses, this depression deepens due to increased pressure inside the eye. This pressure causes mechanical damage to the nerve fibers, leading to thinning and loss of function.
Another crucial area on the retina is the macula, which contains a high density of receptors responsible for image perception. While the entire retina senses images, the macula provides the sharpest, clearest vision. We use this area for tasks like reading, writing, and looking at fine details. Therefore, the damage to the macular area significantly impacts a patient’s visual quality and clarity. Nerve fibers carrying visual information from this crucial region are essential when evaluating the visual field. We prioritize assessing the macula’s health because it directly determines the quality of a patient’s central vision.
Unfortunately, even if the macula is healthy, damage to the nerve fibers transmitting its signals will still compromise vision.
AI for OCT: Early Glaucoma Detection
AI offers valuable insights into glaucoma detection, analyzing changes that may not be visible to the naked eye or even on standard OCT imaging.
The Altris AI?Early Glaucoma Risk Assessment?Module specifically focuses on analyzing the ganglion cell complex, measuring its thickness, and identifying any thinning or asymmetry. These measurements help determine a patient’s glaucoma risk. If the ganglion cell complex has an average thickness and is symmetrical throughout the macula, the module will assign a low probability of Glaucoma.
If you want to read the article, please follow this link.
If you are ready to experience how Altris AI (AI for OCT) analyzes OCT scans to detect early risk of glaucoma based on the GCC asymmetry analysis, please get registered in the Demo Account.