PRIMARY OPEN-ANGLE GLAUCOMA: EARLY DIAGNOSIS, RISK STRATIFICATION AND MODERN MANAGEMENT

ПЕРВИЧНАЯ ОТКРЫТОУГОЛЬНАЯ ГЛАУКОМА: РАННЯЯ ДИАГНОСТИКА, СТРАТИФИКАЦИЯ РИСКА И СОВРЕМЕННЫЕ ПОДХОДЫ К ВЕДЕНИЮ

Садыкова Алтынай Болатовна

врач-резидент-офтальмолог, Казахский научно-исследовательский институт глазных болезней,

Казахстан, г. Алматы

ABSTRACT

Background. Primary open-angle glaucoma is a chronic progressive optic neuropathy and one of the leading causes of irreversible blindness worldwide. The disease is often asymptomatic in the early stages, which makes early detection and regular monitoring essential for preventing visual disability.

Methods. A narrative review of scientific literature published mainly between 2017 and 2026 was conducted. The search was performed in PubMed, Scopus, Web of Science and Google Scholar using the keywords “primary open-angle glaucoma”, “intraocular pressure”, “optic nerve”, “optical coherence tomography”, “visual field”, “glaucoma screening”, “selective laser trabeculoplasty”, “minimally invasive glaucoma surgery” and “treatment adherence”. Clinical guidelines, consensus documents, systematic reviews, narrative reviews and key clinical trials were included.

Result. Current evidence shows that primary open-angle glaucoma is associated with elevated intraocular pressure, older age, family history, myopia, vascular factors, thin central corneal thickness and structural susceptibility of the optic nerve head. Diagnosis requires comprehensive assessment of intraocular pressure, optic disc morphology, retinal nerve fiber layer, ganglion cell complex and visual field function. Modern treatment includes topical hypotensive therapy, laser trabeculoplasty, filtering surgery and minimally invasive glaucoma surgery.

Conclusion. Primary open-angle glaucoma requires early diagnosis, individualized risk assessment and long-term follow-up. A combination of structural and functional testing, intraocular pressure reduction and patient adherence to therapy is essential for slowing disease progression and preserving vision.

АННОТАЦИЯ

Актуальность. Первичная открытоугольная глаукома представляет собой хроническую прогрессирующую оптическую нейропатию и является одной из ведущих причин необратимой слепоты во всем мире. На ранних стадиях заболевание часто протекает бессимптомно, что делает раннее выявление и регулярный мониторинг крайне важными для профилактики зрительной инвалидизации.

Методы. Проведен нарративный обзор научной литературы, опубликованной преимущественно в период с 2017 по 2026 год. Поиск осуществлялся в базах данных PubMed, Scopus, Web of Science и Google Scholar с использованием ключевых слов: «primary open-angle glaucoma», «intraocular pressure», «optic nerve», «optical coherence tomography», «visual field», «glaucoma screening», «selective laser trabeculoplasty», «minimally invasive glaucoma surgery» и «treatment adherence». В обзор были включены клинические рекомендации, консенсусные документы, систематические обзоры, нарративные обзоры и ключевые клинические исследования.

Результат. Современные данные свидетельствуют о том, что первичная открытоугольная глаукома ассоциирована с повышенным внутриглазным давлением, пожилым возрастом, семейным анамнезом, миопией, сосудистыми факторами, тонкой центральной толщиной роговицы и структурной предрасположенностью диска зрительного нерва. Диагностика требует комплексной оценки внутриглазного давления, морфологии диска зрительного нерва, слоя нервных волокон сетчатки, комплекса ганглиозных клеток и функции поля зрения. Современное лечение включает местную гипотензивную терапию, лазерную трабекулопластику, фильтрующие операции и минимально инвазивную хирургию глаукомы.

Заключение. Первичная открытоугольная глаукома требует ранней диагностики, индивидуальной оценки риска и длительного динамического наблюдения. Сочетание структурного и функционального тестирования, снижения внутриглазного давления и приверженности пациента терапии имеет важное значение для замедления прогрессирования заболевания и сохранения зрения.

Keywords: primary open-angle glaucoma, intraocular pressure, optic nerve, optical coherence tomography, visual field, glaucoma treatment.

Ключевые слова: первичная открытоугольная глаукома, внутриглазное давление, зрительный нерв, оптическая когерентная томография, поле зрения, лечение глаукомы.

Introduction

Primary open-angle glaucoma is a chronic progressive optic neuropathy characterized by structural damage to the optic nerve head and corresponding visual field loss. It is one of the most important causes of irreversible blindness, because visual loss caused by glaucomatous damage cannot be restored [1, p. P1; 2, p. 1]. The disease usually develops slowly and remains asymptomatic for a long period, especially when central vision is preserved. As a result, many patients are diagnosed only after significant structural or functional damage has already occurred [3, p. 2081].

The clinical importance of primary open-angle glaucoma is determined by its chronic course, lifelong need for monitoring and potential progression despite treatment. Although elevated intraocular pressure is the most important modifiable risk factor, glaucoma may also develop in patients with statistically normal intraocular pressure. Therefore, diagnosis should not be based on intraocular pressure alone, but should include evaluation of the optic nerve head, retinal nerve fiber layer, ganglion cell complex and visual field [1, p. P1; 4, p. 102].

Modern glaucoma care is based on early detection, risk stratification and individualized management. The main goal of treatment is not complete cure, but reduction of disease progression and preservation of visual function throughout the patient’s lifetime [2, p. 1; 5, p. 1901]. This requires regular follow-up, accurate interpretation of structural and functional changes, appropriate target intraocular pressure and strong patient adherence to therapy [6, p. 1308].

Aim of the Review

The aim of this narrative review was to summarize current evidence on primary open-angle glaucoma, including risk factors, diagnostic approaches, monitoring methods and modern treatment strategies.

Materials and Methods

A narrative review of scientific literature published mainly between 2017 and 2026 was conducted. The search was performed in PubMed, Scopus, Web of Science and Google Scholar. The following keywords and their combinations were used: “primary open-angle glaucoma”, “glaucomatous optic neuropathy”, “intraocular pressure”, “optic nerve head”, “retinal nerve fiber layer”, “optical coherence tomography”, “visual field testing”, “selective laser trabeculoplasty”, “minimally invasive glaucoma surgery” and “treatment adherence”. Clinical guidelines, consensus documents, systematic reviews, narrative reviews and landmark clinical trials addressing diagnosis and treatment of glaucoma were included [1, p. P1; 2, p. 1; 5, p. 1901].

Risk Factors and Pathogenesis

The development and progression of primary open-angle glaucoma are associated with several ocular and systemic risk factors. Elevated intraocular pressure remains the most important modifiable risk factor. Other important risk factors include older age, positive family history, African or Asian ancestry, myopia, thin central corneal thickness, low ocular perfusion pressure, vascular dysregulation and structural features of the optic nerve head [1, p. P1; 2, p. 1; 7, p. 714].

The pathogenesis of glaucoma is multifactorial. Mechanical stress caused by intraocular pressure may damage the lamina cribrosa and retinal ganglion cell axons. At the same time, vascular insufficiency, oxidative stress, mitochondrial dysfunction, neuroinflammation and impaired axonal transport may contribute to retinal ganglion cell death [8, p. 1367; 9, p. 152]. These mechanisms explain why glaucoma may progress even in patients whose intraocular pressure is within the statistically normal range.

Central corneal thickness is clinically important because it affects intraocular pressure measurement and is also considered an independent risk factor for glaucoma progression. The Ocular Hypertension Treatment Study demonstrated that patients with thinner central corneas had a higher risk of developing primary open-angle glaucoma [7, p. 714].

Clinical Features and Disease Progression

Primary open-angle glaucoma usually has an insidious onset. In early stages, patients often do not notice any visual disturbance, because peripheral visual field defects may remain unnoticed. As the disease progresses, arcuate scotomas, nasal steps and paracentral defects may develop. Advanced glaucoma may lead to tunnel vision and severe visual impairment [1, p. P1; 3, p. 2081].

Structural damage often precedes detectable visual field loss. Typical optic nerve changes include enlargement of the cup-to-disc ratio, thinning of the neuroretinal rim, retinal nerve fiber layer defects, disc hemorrhages and asymmetry between eyes [2, p. 1; 4, p. 102]. Because early glaucoma can be clinically subtle, a combination of structural and functional assessment is necessary.

Disease progression varies widely among patients. Some individuals remain stable for many years, while others progress rapidly despite treatment. Risk stratification should consider baseline intraocular pressure, optic nerve status, visual field damage, age, life expectancy, rate of progression and systemic comorbidities [1, p. P1; 5, p. 1901].

Diagnosis

Diagnosis of primary open-angle glaucoma requires a comprehensive ophthalmological examination. It should include measurement of intraocular pressure, gonioscopy to confirm an open anterior chamber angle, optic nerve head assessment, central corneal thickness measurement, retinal imaging and standard automated perimetry [1, p. P1; 2, p. 1].

Optical coherence tomography has become an essential tool in glaucoma diagnosis and monitoring. It allows quantitative assessment of the retinal nerve fiber layer, optic nerve head parameters and macular ganglion cell complex. OCT is particularly useful in early or pre-perimetric glaucoma, when structural changes may be detectable before visual field defects appear [4, p. 102; 10, p. 1].

Standard automated perimetry remains the main method for evaluating functional damage. Visual field testing allows detection of characteristic glaucomatous defects and monitoring of progression over time. However, perimetry depends on patient cooperation and may show variability; therefore, results should be interpreted together with structural findings [1, p. P1; 2, p. 1].

Gonioscopy is necessary to distinguish open-angle glaucoma from angle-closure mechanisms. Failure to assess the anterior chamber angle may lead to incorrect classification and inappropriate treatment strategy [2, p. 1].

Monitoring and Target Intraocular Pressure

The concept of target intraocular pressure is central to glaucoma management. Target pressure is an estimated level at which further optic nerve damage is unlikely to occur or is expected to progress slowly enough to preserve vision during the patient’s lifetime [1, p. P1; 2, p. 1]. It is not fixed and should be adjusted according to disease severity, risk factors and evidence of progression.

Patients with early glaucoma may require moderate intraocular pressure reduction, whereas those with advanced disease or rapid progression often need lower target pressure. The Early Manifest Glaucoma Trial and other landmark studies demonstrated that lowering intraocular pressure reduces the risk of glaucoma progression [11, p. 1268; 12, p. 498].

Monitoring should include repeated intraocular pressure measurements, optic nerve evaluation, OCT and visual field testing. Structural and functional progression do not always occur simultaneously; therefore, both modalities are necessary for reliable follow-up [4, p. 102; 10, p. 1].

Treatment Principles

The main goal of treatment is to reduce intraocular pressure and slow disease progression. First-line treatment traditionally includes topical hypotensive medications, such as prostaglandin analogues, beta-blockers, carbonic anhydrase inhibitors, alpha-agonists and fixed combinations [1, p. P1; 2, p. 1].

Long-term topical therapy may be limited by ocular surface disease, local adverse effects, cost, complex regimens and poor adherence. Non-adherence is one of the major reasons for inadequate intraocular pressure control and disease progression [6, p. 1308]. Therefore, treatment should be simple, tolerable and understandable for the patient.

Selective laser trabeculoplasty has become an important option for initial or adjunctive therapy. The LiGHT trial showed that selective laser trabeculoplasty can provide effective intraocular pressure control and may reduce the need for topical medications in many patients with open-angle glaucoma or ocular hypertension [13, p. 1505].

Surgical treatment is indicated when medical and laser therapy are insufficient to achieve target pressure or when disease progression continues despite treatment. Trabeculectomy and glaucoma drainage devices remain important options for advanced or uncontrolled glaucoma [14, p. 789; 15, p. 333]. Minimally invasive glaucoma surgery has expanded surgical options, particularly for patients with mild to moderate glaucoma, often in combination with cataract surgery [16, p. e0183142].

Patient Adherence and Quality of Life

Glaucoma treatment is long-term and requires active patient participation. Many patients do not feel symptoms in early stages, which may reduce motivation to use medications regularly. Poor adherence may result from forgetfulness, side effects, difficulty instilling eye drops, low understanding of disease seriousness or financial barriers [6, p. 1308; 17, p. 238939].

Patient education is an essential part of glaucoma management. Patients should understand that glaucoma may progress silently and that the purpose of treatment is to preserve existing vision rather than improve already lost visual function [1, p. P1; 6, p. 1308].

Glaucoma also affects quality of life. Progressive visual field loss may impair reading, driving, walking, facial recognition and daily independence. Fear of blindness and treatment burden may increase psychological stress. For this reason, management should include not only pressure reduction, but also assessment of functional status, patient preferences and quality of life [18, p. 546].

Emerging Technologies and Future Directions

Modern glaucoma care is increasingly supported by digital technologies. Artificial intelligence and machine learning are being studied for automated detection of glaucomatous optic neuropathy, OCT interpretation and visual field progression analysis [19, p. 16685]. These tools may improve screening efficiency and support clinical decision-making, especially in regions with limited access to glaucoma specialists.

OCT angiography is another promising technology. It allows non-invasive assessment of optic nerve head and peripapillary microvasculature. Several studies suggest that vascular parameters may be associated with glaucomatous damage and progression, although OCT angiography is not yet a replacement for standard diagnostic methods [10, p. 1].

Conclusion

Primary open-angle glaucoma is a chronic progressive optic neuropathy that may lead to irreversible blindness if not detected and treated in time. Since the disease is often asymptomatic in early stages, regular ophthalmological examination and risk-based screening are essential [1, p. P1; 2, p. 1].

Modern diagnosis requires a combination of intraocular pressure measurement, gonioscopy, optic nerve assessment, optical coherence tomography and visual field testing. Treatment should be individualized and aimed at achieving target intraocular pressure sufficient to slow disease progression [1, p. P1; 4, p. 102].

Topical medications, selective laser trabeculoplasty and surgical methods remain the main treatment options. Long-term success depends not only on the chosen therapy, but also on patient adherence, regular monitoring and timely treatment adjustment. Early diagnosis, patient education and individualized follow-up are key strategies for preserving vision and reducing the burden of glaucoma [6, p. 1308; 13, p. 1505].

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