40-440: H42 or H-42 may refer to: H-42 (Michigan county highway) Glaucoma HMS Arrow (H42) , a Royal Navy A-class destroyer HMS H42 , a Royal Navy H-class submarine H-42, an H-class battleship proposal for Germany's Kriegsmarine during World War II [REDACTED] Topics referred to by the same term This disambiguation page lists articles associated with
80-418: A chronic, painless buildup of pressure in the eye. In primary angle closure glaucoma, the iridocorneal angle is narrowed or completely closed obstructing the flow of aqueous humor to the trabecular meshwork for drainage. This is usually due to the forward displacement of the iris against the cornea, resulting in angle closure. This accumulation of aqueous humor causes an acute increase in pressure and damage to
120-402: A lack of aqueous misdirection. Also, the corneal appearance is not as hazy. A reduction in visual acuity can occur followed neuroretinal breakdown. Absolute glaucoma (H44.5) is the end stage of all types of glaucoma. The eye has no vision, absence of pupillary light reflex and pupillary response , and has a stony appearance. Severe pain is present in the eye. The treatment of absolute glaucoma
160-412: A medical emergency due to the risk of impending permanent vision loss, is characterized by sudden ocular pain, seeing halos around lights, red eye , very high intraocular pressure , nausea and vomiting, and suddenly decreased vision. Acute angle closure glaucoma may further present with corneal edema, engorged conjunctival vessels and a fixed and dilated pupil on examination. Opaque specks may occur in
200-457: A primary neurodegenerative process may be responsible for degeneration at the optic nerve head in glaucoma. This would be consistent with a possible mechanism of normal tension glaucoma (those with open-angle glaucoma with normal eye pressures) and is supported by evidence showing a correlation of glaucoma with Alzheimer's dementia and other causes of cognitive decline. Both experimental and clinical studies implicate that oxidative stress plays
240-642: A role in the pathogenesis of open-angle glaucoma as well as in Alzheimer's disease. Degeneration of axons of the retinal ganglion cells (the optic nerve) is a hallmark of glaucoma. The inconsistent relationship of glaucomatous optic neuropathy with increased intraocular pressure has provoked hypotheses and studies on anatomic structure, eye development, nerve compression trauma, optic nerve blood flow, excitatory neurotransmitter, trophic factor, retinal ganglion cell or axon degeneration, glial support cell, immune system, aging mechanisms of neuron loss, and severing of
280-464: Is a destructive procedure like cyclocryoapplication, cyclophotocoagulation, or injection of 99% alcohol. In glaucoma visual field defects result from damage to the retinal nerve fiber layer (RNFL). Field defects are seen mainly in primary open angle glaucoma. Because of the unique anatomy of the RNFL, many noticeable patterns are seen in the visual field. Most of the early glaucomatous changes are seen within
320-406: Is a function of production of liquid aqueous humor by the ciliary processes of the eye, and its drainage through the trabecular meshwork. Aqueous humor flows from the ciliary processes into the posterior chamber , bounded posteriorly by the lens and the zonules of Zinn , and anteriorly by the iris . It then flows through the pupil of the iris into the anterior chamber , bounded posteriorly by
360-435: Is a group of eye diseases that can lead to damage of the optic nerve . The optic nerve transmits visual information from the eye to the brain. Glaucoma may cause vision loss if left untreated. It has been called the "silent thief of sight" because the loss of vision usually occurs slowly over a long period of time. A major risk factor for glaucoma is increased pressure within the eye, known as intraocular pressure (IOP) . It
400-546: Is a leading cause of blindness in African Americans , Hispanic Americans , and Asians. It occurs more commonly among older people, and closed-angle glaucoma is more common in women. In 2013 for the population aged 40-80 years the global prevalence of glaucoma was estimated at 3.54%, thus affecting 64.3 million worldwide. The same year, there were 2.97 million people in North America with open angle glaucoma. By 2040,
440-612: Is a matter of debate whether every person with an elevated intraocular pressure should receive glaucoma therapy. As of 2018, most ophthalmologists favored treatment of those with additional risk factors. For eye pressures, a value of 28 hPa (21 mmHg) above atmospheric pressure 1,010 hPa (760 mmHg) is often used, with higher pressures leading to a greater risk. However, some may have high eye pressure for years and never develop damage. Conversely, optic nerve damage may occur with normal pressure, known as normal-tension glaucoma. In case of above-normal intraocular pressure,
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#1732858713418480-488: Is also associated with genetic mutations (including OPA1 and OPTN genes). Additionally, there are some rare genetic conditions that increase the risk of glaucoma, such as Axenfeld-Rieger syndrome and primary congenital glaucoma , which is associated with mutations in CYP1B1 or LTBP2 . They are inherited in an autosomal recessive fashion. Axenfeld-Rieger syndrome is inherited in an autosomal dominant fashion and
520-503: Is also considered as consequence and cause of vision loss which means that stress management training, autogenic training and other techniques to cope with stress can be helpful. There are several pressure-lowering medication groups that could be used in lowering the IOP, usually eyedrops. The choice of medication usually depends on the dose, duration and the side effects of each medication. However, in general, prostaglandin analogues are
560-436: Is an emergency requiring immediate attention. If treated early, it is possible to slow or stop the progression of glaucoma. Regular eye examinations, especially if the person is over 40 or has a family history of glaucoma, are essential for early detection. Treatment typically includes prescription of eye drops, medication , laser treatment or surgery. The goal of these treatments is to decrease eye pressure. Glaucoma
600-616: Is associated with PITX2 or FOXC1 . The total prevalence of glaucoma is about the same in North America and Asia. However, the prevalence of angle-closure glaucoma is four times higher in Asia than in North America. In the United States, glaucoma is more common in African Americans , Latinos and Asian-Americans . Other factors can cause glaucoma, known as "secondary glaucoma", including prolonged use of steroids (steroid-induced glaucoma); conditions that severely restrict blood flow to
640-559: Is associated with old age, a family history of glaucoma, and certain medical conditions or the use of some medications. The word glaucoma comes from the Ancient Greek word γλαυκός ( glaukós ), meaning 'gleaming, blue-green, gray'. There are different types of glaucoma, but the most common are called open-angle glaucoma and closed-angle glaucoma . Inside the eye, a liquid called aqueous humor helps to maintain shape and provides nutrients. The aqueous humor normally drains through
680-601: Is increased about two- to four-fold for people who have a sibling with glaucoma. Glaucoma, particularly primary open-angle glaucoma, is associated with mutations in several genes , including MYOC , ASB10, WDR36 , NTF4 , TBK1 , and RPGRIP1 . Many of these genes are involved in critical cellular processes that are implicated in the development and progression of glaucoma, including regulation of intraocular pressure, retinal ganglion cell health, and optic nerve function. Normal-tension glaucoma, which comprises 30-90% of primary open-angle glaucoma (depending on ethnic group),
720-431: Is open-angle glaucoma with an unexplained significant rise of intraocular pressure following unknown pathogenesis. Intraocular pressure can sometimes reach 80 mmHg (11 kPa). It characteristically manifests as ciliary body inflammation and massive trabecular edema that sometimes extends to Schlemm's canal. This condition is differentiated from malignant glaucoma by the presence of a deep and clear anterior chamber and
760-585: The lamina cribrosa . Thus increases in intraocular pressure would cause nerve damage as seen in glaucoma. The vascular theory hypothesizes that a decreased blood supply to the retinal ganglions cells leads to nerve damage. This decrease in blood supply may be due to increasing intraocular pressures, and may also be due to systemic hypotension, vasospasm or atherosclerosis. This is supported by evidence that those with low blood pressure, particularly low diastolic blood pressure, are at an increased risk of glaucoma. The primary neurodegeneration theory hypothesizes that
800-421: The retina or ciliary body . Individuals with poor blood flow to the eye are highly at risk for this condition. Neovascular glaucoma results when new, abnormal vessels begin developing in the angle of the eye that begin blocking the drainage. People with such condition begin to rapidly lose their eyesight. Sometimes, the disease appears very rapidly, especially after cataract surgery procedures. Toxic glaucoma
840-425: The trabecular meshwork . In open-angle glaucoma, the draining is impeded, causing the liquid to accumulate and pressure inside the eye to increase. This elevated pressure can damage the optic nerve. In closed-angle glaucoma, the drainage of the eye becomes suddenly blocked, leading to a rapid increase in intraocular pressure. This may lead to intense eye pain , blurred vision , and nausea . Closed-angle glaucoma
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#1732858713418880-641: The American Academy of Ophthalmology. There is a glaucoma screening program in the UK. Those at risk are advised to have an eye examination at least once a year. The goal of glaucoma management for patients with increased intraocular pressure is to decrease the intraocular pressure (IOP), thus slowing the progression of glaucoma and preserving the quality of life for patients, with minimal side-effects. This requires appropriate diagnostic techniques and follow-up examinations, and judicious selection of treatments for
920-498: The U.S. had glaucoma, with 1.49 million experiencing vision impairment due to the condition, according to a meta-analysis. The study found that Black adults were about twice as likely to be affected by glaucoma as white adults. Glaucoma prevalence was 1.62% among individuals aged 18 and older and 2.56% among those aged 40 and older, while vision-affecting glaucoma occurred in 0.57% and 0.91% of these age groups, respectively. Open angle glaucoma usually presents with no symptoms early in
960-439: The aqueous humor from the eye. This contact between iris and trabecular meshwork (TM) may gradually damage the function of the meshwork until it fails to keep pace with aqueous production, and the pressure rises. In over half of all cases, prolonged contact between iris and TM causes the formation of synechiae (effectively "scars"). These cause permanent obstruction of aqueous outflow. In some cases, pressure may rapidly build up in
1000-505: The central visual field, mainly in Bjerrum's area, 10-20° from fixation. Following are the common glaucomatous field defects: The United States Preventive Services Task Force stated, as of 2013, that there was insufficient evidence to recommend for or against screening for glaucoma. Therefore, there is no national screening program in the US. Screening, however, is recommended starting at age 40 by
1040-491: The course of the disease. However, it may gradually progress to involve difficulties with vision. It usually involves deficits in the peripheral vision followed by central vision loss as the disease progresses, but less commonly it may present as central vision loss or patchy areas of vision loss. On an eye examination, optic nerve changes are seen indicating damage to the optic nerve head (increased cup-to-disc ratio on fundoscopic examination ). Acute angle closure glaucoma,
1080-431: The drainage angle ( gonioscopy ), and retinal nerve fiber layer assessment with a fundus examination, measuring corneal thickness ( pachymetry ), and visual field testing . Glaucoma has been classified into specific types: Primary glaucoma (H40.1-H40.2) Variants of primary glaucoma Primary angle closure glaucoma is caused by contact between the iris and trabecular meshwork, which in turn obstructs outflow of
1120-407: The eye) is an important risk factor for glaucoma, but only about 10-70% of people - depending on ethnic group - with primary open-angle glaucoma actually have elevated ocular pressure. Ocular hypertension—an intraocular pressure above the traditional threshold of 21 mmHg (28 hPa) or even above 24 mmHg (32 hPa)—is not necessarily a pathological condition, but it increases
1160-408: The eye, causing pain and redness (symptomatic, or so-called "acute" angle closure). In this situation, the vision may become blurred, and halos may be seen around bright lights. Accompanying symptoms may include a headache and vomiting. Diagnosis is made from physical signs and symptoms: pupils mid-dilated and unresponsive to light, cornea edematous (cloudy), reduced vision, redness, and pain. However,
1200-553: The eye, such as severe diabetic retinopathy and central retinal vein occlusion (neovascular glaucoma); ocular trauma (angle-recession glaucoma); plateau iris ; and inflammation of the middle layer of the pigmented vascular eye structure ( uveitis ), known as uveitic glaucoma . The main effect of glaucoma is damage to the optic nerve. Eventually, this damage leads to vision loss, which can deteriorate with time. The underlying cause of open-angle glaucoma remains unclear. Several theories exist on its exact etiology. Intraocular pressure
1240-510: The individual patient. Although increased IOP is only one of the major risk factors for glaucoma, lowering it via various pharmaceuticals and/or surgical techniques is currently the mainstay of glaucoma treatment. Vascular flow and neurodegenerative theories of glaucomatous optic neuropathy have prompted studies on various neuroprotective therapeutic strategies, including nutritional compounds, some of which may be regarded by clinicians as safe for use now, while others are on trial. Mental stress
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1280-479: The iris and anteriorly by the cornea . From here, the trabecular meshwork drains aqueous humor via the scleral venous sinus ( Schlemm's canal ) into scleral plexuses and general blood circulation. In open/wide-angle glaucoma, flow is reduced through the trabecular meshwork, due to the degeneration and obstruction of the trabecular meshwork, whose original function is to absorb the aqueous humor. Loss of aqueous humor absorption leads to increased resistance and thus
1320-415: The lens in glaucoma, known as glaukomflecken. The word is German, meaning "glaucoma-specks". Glaucoma can affect anyone. Some people have a higher risk or susceptibility to develop glaucoma due to certain risk factors . Risk factors for glaucoma include increasing age, high intraocular pressure, a family history of glaucoma, and use of steroid medication. Ocular hypertension (increased pressure within
1360-524: The majority of cases are asymptomatic. Prior to the very severe loss of vision, these cases can only be identified by examination, generally by an eye care professional. Developmental glaucoma (Q15.0) Secondary glaucoma (H40.3-H40.6) Neovascular glaucoma , an uncommon type of glaucoma, is difficult or nearly impossible to treat, and is often caused by proliferative diabetic retinopathy (PDR) or central retinal vein occlusion (CRVO). It may also be triggered by other conditions that result in ischemia of
1400-431: The mechanism of open-angle glaucoma is believed to be the impeded exit of aqueous humor through the trabecular meshwork, while in closed-angle glaucoma the iris blocks the trabecular meshwork. Diagnosis is achieved by performing an eye examination . Often, the optic nerve shows an abnormal amount of cupping . Positive family history is a risk factor for glaucoma. The relative risk of having primary open-angle glaucoma
1440-467: The nerve fibers at the scleral edge. Screening for glaucoma is an integral part of a standard eye examination performed by optometrists and ophthalmologists. The workup for glaucoma involves taking a thorough case history, with the emphasis on assessment of risk factors. The baseline glaucoma evaluation tests include intraocular pressure measurement by using tonometry, anterior chamber angle assessment by optical coherence tomography , inspecting
1480-438: The optic nerve. The pathophysiology of glaucoma is not well understood. There are several theories regarding the mechanism of the damage to the optic nerve in glaucoma. The biomechanical theory hypothesizes that the retinal ganglion cell axons (which form the optic nerve head and the retinal nerve fiber layer) are particularly susceptible to mechanical damage from increases in the intraocular pressure as they pass through pores at
1520-756: The prevalence of all types of glaucoma was projected to increase to 111.82 million worldwide and to 4.72 million in North America. Globally, glaucoma is the second-leading cause of blindness , while cataracts are a more common cause. In the United States, glaucoma is a leading cause of blindness for African Americans, who have higher rates of primary open-angle glaucoma, and Hispanic Americans . Bilateral vision loss can negatively affect mobility and interfere with driving. A meta-analysis published in 2009 found that people with primary open angle glaucoma do not have increased mortality rates , or increased risk of cardiovascular death. A 2024 JAMA Ophthalmology reports that in 2022 an estimated 4.22 million people in
1560-479: The risk of developing glaucoma. A study with 1636 persons aged 40-80 who had an intraocular pressure above 24 mmHg in at least one eye but no indications of eye damages showed that after five years 9.5% of the untreated participants and 4.4% of the treated participants had developed glaucomatous symptoms, meaning that only about one in ten untreated people with elevated intraocular pressure will develop glaucomatous symptoms over that period of time. Therefore, it
1600-506: The same title formed as a letter–number combination. If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=H42&oldid=1085878859 " Category : Letter–number combination disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Glaucoma Glaucoma
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