Glaucoma is one of the leading causes of blindness in the general population, and open-angle glaucoma is the most common form [1] [2] [3]. Numerous risk factors for this disorder have been identified, including older age, genetic factors (a seven-fold increased risk is confirmed in the setting of a positive family history), trauma, use of corticosteroids (either topical or systemic), black race, and high intraocular pressure, which is considered to be the main event in the pathogenesis [3] [4] [5]. Unfortunately, one of the most prominent clinical features of glaucoma is that its symptoms appear only when substantial damage to the optic nerve and disk occurs [3] [4]. In fact, open-angle glaucoma is usually diagnosed incidentally, when examination of the eye is performed due to other causes [5]. Studies have shown that loss of more than 40% of optic nerve fibers is necessary to produce symptoms [5], and patients report a gradual loss of peripheral vision that is often perceived as tunnel vision [5] [6]. In most patients, open- angle glaucoma appears bilaterally, and inability to perform daily activities, such as driving and newspaper reading is often a consequence of the reduced visual field, while some patients report missing stairs as well [4]. Glaucoma invariably causes irreversible blindness in the absence of a timely diagnosis and an early appearance of vision-related symptoms must be taken seriously for that reason.

The diagnostic workup of patients reporting vision impairment must start with a thorough patient history that can reveal the presence of risk factors and assess the course and progression of symptoms. A positive family history, previous eye-related disorders and potential use of corticosteroids must be noted. A physical examination including visual field examination should be performed. As symptoms may be absent in the early stages, direct ophthalmoscopy is also recommended as a mandatory part of primary practice [3] [4] [5]. A more detailed ophthalmoscopic examination, however, is required to confirm glaucoma and various non-invasive procedures and these may be [4] [5] [7]:

• Perimetry - Because of its ability to provide a direct view of the patient's visual fields, this computer-based procedure is considered to be the mainstay in diagnosis and management of glaucoma [5].
• Optical coherence tomography (OCT) - Used to assess the optic nerve head and the retina by creating cross-sectional images [7], OCT is also frequently implemented in glaucoma workup. A more advanced form possessing an increased resolution and faster scanning speed, spectral domain (SD)-OCT, was recently introduced in ophthalmology, providing an even better view of the damaged structures [7].
• Scanning laser polarimetry and ophthalmoscopy - Measurement of the optic nerve fiber thickness and quantitative detection of viable retinal cells is achieved by these methods, respectively, which may be quite useful when the disease is in its initial stages.

1. Weinreb RN, Khaw PT. Primary open-angle glaucoma. Lancet. 2004;363:1711–1720.
2. Beidoe G, Mousa SA. Current primary open-angle glaucoma treatments and future directions. Clin Ophthalmol. 2012;6:1699-1707.
3. Porter RS, Kaplan JL. Merck Manual of Diagnosis and Therapy. 19th Edition. Merck Sharp & Dohme Corp. Whitehouse Station, N.J; 2011.
4. Weinreb RN, Aung T, Medeiros FA. The pathophysiology and treatment of glaucoma: a review. JAMA. 2014;14;311(18):1901-1111.
5. Distelhorst JS, Hughes GM. Open-Angle Glaucoma. Am Fam Physician. 2003;67:1937–44.
6. Hu CX, Zangalli C, Hsieh M, et al. What Do Patients With Glaucoma See? Visual Symptoms Reported by Patients With Glaucoma. Am J Med Sci. 2014;348(5):403-409.
7. Bussel II, Wollstein G, Schuman JS. OCT for glaucoma diagnosis, screening and detection of glaucoma progression. Br J Ophthalmol. 2014;98(2):ii15-ii19.