Glaucoma

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Glaucoma_table_infobox_0

GlaucomaGlaucoma_header_cell_0_0_0
SpecialtyGlaucoma_header_cell_0_1_0 OphthalmologyGlaucoma_cell_0_1_1
SymptomsGlaucoma_header_cell_0_2_0 Vision loss, eye pain, mid-dilated pupil, redness of the eye, nauseaGlaucoma_cell_0_2_1
Usual onsetGlaucoma_header_cell_0_3_0 Gradual, or suddenGlaucoma_cell_0_3_1
Risk factorsGlaucoma_header_cell_0_4_0 Increased pressure in the eye, family history, high blood pressureGlaucoma_cell_0_4_1
Diagnostic methodGlaucoma_header_cell_0_5_0 Dilated eye examinationGlaucoma_cell_0_5_1
Differential diagnosisGlaucoma_header_cell_0_6_0 Uveitis, trauma, keratitis, conjunctivitisGlaucoma_cell_0_6_1
TreatmentGlaucoma_header_cell_0_7_0 Medication, laser, surgeryGlaucoma_cell_0_7_1
FrequencyGlaucoma_header_cell_0_8_0 6–67 millionGlaucoma_cell_0_8_1

Glaucoma is a group of eye diseases which result in damage to the optic nerve and cause vision loss. Glaucoma_sentence_0

The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye remains open, with less common types including closed-angle (narrow angle, acute congestive) glaucoma and normal-tension glaucoma. Glaucoma_sentence_1

Open-angle glaucoma develops slowly over time and there is no pain. Glaucoma_sentence_2

Peripheral vision may begin to decrease, followed by central vision, resulting in blindness if not treated. Glaucoma_sentence_3

Closed-angle glaucoma can present gradually or suddenly. Glaucoma_sentence_4

The sudden presentation may involve severe eye pain, blurred vision, mid-dilated pupil, redness of the eye, and nausea. Glaucoma_sentence_5

Vision loss from glaucoma, once it has occurred, is permanent. Glaucoma_sentence_6

Eyes affected by glaucoma are referred to as being glaucomatous. Glaucoma_sentence_7

Risk factors for glaucoma include increasing age, high pressure in the eye, a family history of glaucoma, and use of steroid medication. Glaucoma_sentence_8

For eye pressures, a value of greater than 21 mmHg or 2.8 kPa is often used, with higher pressures leading to a greater risk. Glaucoma_sentence_9

However, some may have high eye pressure for years and never develop damage. Glaucoma_sentence_10

Conversely, optic nerve damage may occur with normal pressure, known as normal-tension glaucoma. Glaucoma_sentence_11

The mechanism of open-angle glaucoma is believed to be slow exit of aqueous humor through the trabecular meshwork, while in closed-angle glaucoma the iris blocks the trabecular meshwork. Glaucoma_sentence_12

Diagnosis is by a dilated eye examination. Glaucoma_sentence_13

Often, the optic nerve shows an abnormal amount of cupping. Glaucoma_sentence_14

If treated early, it is possible to slow or stop the progression of disease with medication, laser treatment, or surgery. Glaucoma_sentence_15

The goal of these treatments is to decrease eye pressure. Glaucoma_sentence_16

A number of different classes of glaucoma medication are available. Glaucoma_sentence_17

Laser treatments may be effective in both open-angle and closed-angle glaucoma. Glaucoma_sentence_18

A number of types of glaucoma surgeries may be used in people who do not respond sufficiently to other measures. Glaucoma_sentence_19

Treatment of closed-angle glaucoma is a medical emergency. Glaucoma_sentence_20

About 70 million people have glaucoma globally. Glaucoma_sentence_21

The disease affects about 2 million people in the United States. Glaucoma_sentence_22

It occurs more commonly among older people. Glaucoma_sentence_23

Closed-angle glaucoma is more common in women. Glaucoma_sentence_24

Glaucoma has been called the "silent thief of sight," because the loss of vision usually occurs slowly over a long period of time. Glaucoma_sentence_25

Worldwide, glaucoma is the second-leading cause of blindness after cataracts. Glaucoma_sentence_26

Cataracts caused 51% of blindness in 2010, while glaucoma caused 8%. Glaucoma_sentence_27

The word "glaucoma" is from Ancient Greek glaukos, which means "shimmering." Glaucoma_sentence_28

In English, the word was used as early as 1587 but did not become commonly used until after 1850, when the development of the ophthalmoscope allowed people to see the optic nerve damage. Glaucoma_sentence_29

Signs and symptoms Glaucoma_section_0

Open-angle glaucoma is usually painless with no symptoms early in the disease process, thus screening via regular eye check-ups important. Glaucoma_sentence_30

The only signs are gradually progressive visual field loss, and optic nerve changes (increased cup-to-disc ratio on fundoscopic examination). Glaucoma_sentence_31

About 10% of people with closed angles present with acute angle closure characterized by sudden ocular pain, seeing halos around lights, red eye, very high intraocular pressure (>30 mmHg), nausea and vomiting, suddenly decreased vision, and a fixed, mid-dilated pupil. Glaucoma_sentence_32

It is also associated with an oval pupil in some cases. Glaucoma_sentence_33

Acute angle closure is an emergency. Glaucoma_sentence_34

Opaque specks may occur in the lens in glaucoma, known as glaukomflecken. Glaucoma_sentence_35

Causes Glaucoma_section_1

Of the several causes for glaucoma, ocular hypertension (increased pressure within the eye) is the most important risk factor in most glaucomas, but in some populations, only 50% of people with primary open-angle glaucoma actually have elevated ocular pressure. Glaucoma_sentence_36

Ocular hypertension—an intraocular pressure above the traditional threshold of 21 mm Hg or even above 24 mm Hg—is not necessarily a pathological condition but it increases the risk of developing glaucoma. Glaucoma_sentence_37

One study found a conversion rate of 18% within 5 years, meaning less than 1 in 5 people with an elevated intraocular pressure will develop glaucomatous visual field loss over that period of time. Glaucoma_sentence_38

It is a matter of debate whether every person with an elevated intraocular pressure should receive glaucoma therapy; currently most ophthalmologists favor treatment of people with additional risk factors. Glaucoma_sentence_39

Open-angle glaucoma accounts for 90% of glaucoma cases in the United States. Glaucoma_sentence_40

Closed-angle glaucoma accounts for less than 10% of glaucoma cases in the United States, but as many as half of glaucoma cases in other nations (particularly East Asian countries). Glaucoma_sentence_41

Dietary Glaucoma_section_2

No clear evidence indicates that vitamin deficiencies cause glaucoma in humans. Glaucoma_sentence_42

It follows, then, that oral vitamin supplementation is not a recommended treatment for glaucoma. Glaucoma_sentence_43

Caffeine increases intraocular pressure in those with glaucoma, but does not appear to affect normal individuals. Glaucoma_sentence_44

Ethnicity Glaucoma_section_3

Many people of East Asian descent are prone to developing angle closure glaucoma due to shallower anterior chamber depths, with the majority of cases of glaucoma in this population consisting of some form of angle closure. Glaucoma_sentence_45

Higher rates of glaucoma have also been reported for Inuit populations, compared to White populations, in Canada and Greenland. Glaucoma_sentence_46

Genetics Glaucoma_section_4

Positive family history is a risk factor for glaucoma. Glaucoma_sentence_47

The relative risk of having primary open-angle glaucoma (P.O.A.G.) Glaucoma_sentence_48

is increased about two- to four-fold for people who have a sibling with glaucoma. Glaucoma_sentence_49

Glaucoma, particularly primary open-angle glaucoma, is associated with mutations in several genes, including MYOC, ASB10, WDR36, NTF4, TBK1, and RPGRIP1, although most cases of glaucoma do not involve these genetic mutations. Glaucoma_sentence_50

Normal-tension glaucoma, which comprises one-third of POAG, is also associated with genetic mutations (including OPA1 and OPTN genes). Glaucoma_sentence_51

Various rare congenital/genetic eye malformations are associated with glaucoma. Glaucoma_sentence_52

Occasionally, failure of the normal third-trimester gestational atrophy of the hyaloid canal and the tunica vasculosa lentis is associated with other anomalies. Glaucoma_sentence_53

Angle closure-induced ocular hypertension and glaucomatous optic neuropathy may also occur with these anomalies, and has been modelled in mice. Glaucoma_sentence_54

Other Glaucoma_section_5

Other factors can cause glaucoma, known as "secondary glaucoma", including prolonged use of steroids (steroid-induced glaucoma); conditions that severely restrict blood flow to the eye, such as severe diabetic retinopathy and central retinal vein occlusion (neovascular glaucoma); ocular trauma (angle-recession glaucoma); and inflammation of the middle layer of the pigmented vascular eye structure (uveitis), known as uveitic glaucoma. Glaucoma_sentence_55

Pathophysiology Glaucoma_section_6

The underlying cause of open-angle glaucoma remains unclear. Glaucoma_sentence_56

Several theories exist on its exact etiology. Glaucoma_sentence_57

However, the major risk factor for most glaucomas and the focus of treatment is increased intraocular pressure. Glaucoma_sentence_58

Intraocular pressure is a function of production of liquid aqueous humor by the ciliary processes of the eye, and its drainage through the trabecular meshwork. Glaucoma_sentence_59

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. Glaucoma_sentence_60

It then flows through the pupil of the iris into the anterior chamber, bounded posteriorly by the iris and anteriorly by the cornea. Glaucoma_sentence_61

From here, the trabecular meshwork drains aqueous humor via the scleral venous sinus (Schlemm's canal) into scleral plexuses and general blood circulation. Glaucoma_sentence_62

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. Glaucoma_sentence_63

Loss of aqueous humor absorption leads to increased resistance and thus a chronic, painless buildup of pressure in the eye. Glaucoma_sentence_64

In close/narrow-angle, the iridocorneal angle is completely closed because of forward displacement of the final roll and root of the iris against the cornea, resulting in the inability of the aqueous fluid to flow from the posterior to the anterior chamber and then out of the trabecular network. Glaucoma_sentence_65

This accumulation of aqueous humor causes an acute increase in pressure and pain. Glaucoma_sentence_66

Degeneration of axons of the retinal ganglion cells (the optic nerve) is a hallmark of glaucoma. Glaucoma_sentence_67

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/axon degeneration, glial support cell, immune system, aging mechanisms of neuron loss, and severing of the nerve fibers at the scleral edge. Glaucoma_sentence_68

Diagnosis Glaucoma_section_7

Screening for glaucoma is usually performed as part of a standard eye examination performed by optometrists and ophthalmologists. Glaucoma_sentence_69

Testing for glaucoma should include measurements of the intraocular pressure via tonometry, anterior chamber angle examination or gonioscopy, and examination of the optic nerve to look for any visible damage to it, or change in the cup-to-disc ratio and also rim appearance and vascular change. Glaucoma_sentence_70

A formal visual field test should be performed. Glaucoma_sentence_71

The retinal nerve fiber layer can be assessed with imaging techniques such as optical coherence tomography, scanning laser polarimetry, and/or scanning laser ophthalmoscopy (Heidelberg retinal tomogram). Glaucoma_sentence_72

Visual field loss is the most specific sign of the condition; however, it occurs later in the condition. Glaucoma_sentence_73

Owing to the sensitivity of all methods of tonometry to corneal thickness, methods such as Goldmann tonometry should be augmented with pachymetry to measure the central corneal thickness (CCT). Glaucoma_sentence_74

A thicker-than-average cornea can result in a pressure reading higher than the 'true' pressure whereas a thinner-than-average cornea can produce a pressure reading lower than the 'true' pressure. Glaucoma_sentence_75

Because pressure measurement error can be caused by more than just CCT (i.e., corneal hydration, elastic properties, etc.), it is impossible to 'adjust' pressure measurements based only on CCT measurements. Glaucoma_sentence_76

The frequency doubling illusion can also be used to detect glaucoma with the use of a frequency doubling technology perimeter. Glaucoma_sentence_77

Examination for glaucoma also could be assessed with more attention given to sex, race, history of drug use, refraction, inheritance and family history. Glaucoma_sentence_78

Glaucoma_table_general_1

Glaucoma testsGlaucoma_table_caption_1
Glaucoma_header_cell_1_0_0 What the test examinesGlaucoma_header_cell_1_0_1 Eye drops usedGlaucoma_header_cell_1_0_2 Physical contact with the eyeGlaucoma_header_cell_1_0_3 ProcedureGlaucoma_header_cell_1_0_4
TonometryGlaucoma_cell_1_1_0 Inner eye pressureGlaucoma_cell_1_1_1 MaybeGlaucoma_cell_1_1_2 MaybeGlaucoma_cell_1_1_3 Eye drops may be used to numb the eye. The examiner then uses a tonometer to measure the inner pressure of the eye through pressure applied by a puff of warm air or a tiny tool.Glaucoma_cell_1_1_4
Ophthalmoscopy (dilated eye examination)Glaucoma_cell_1_2_0 Shape and color of the optic nerveGlaucoma_cell_1_2_1 YesGlaucoma_cell_1_2_2 NoGlaucoma_cell_1_2_3 Eye drops are used to dilate the pupil. Using a small magnification device with a light on the end, the examiner can examine the magnified optic nerve.Glaucoma_cell_1_2_4
Perimetry (visual field test)Glaucoma_cell_1_3_0 Complete field of visionGlaucoma_cell_1_3_1 NoGlaucoma_cell_1_3_2 NoGlaucoma_cell_1_3_3 The patient looks straight ahead and is asked to indicate when light passes the patient's peripheral field of vision. This allows the examiner to map the patient's field of vision.Glaucoma_cell_1_3_4
GonioscopyGlaucoma_cell_1_4_0 Angle in the eye where the iris meets the corneaGlaucoma_cell_1_4_1 YesGlaucoma_cell_1_4_2 YesGlaucoma_cell_1_4_3 Eye drops are used to numb the eye. A hand-held contact lens with a mirror is placed gently on the eye to allow the examiner to see the angle between the cornea and the iris.Glaucoma_cell_1_4_4
PachymetryGlaucoma_cell_1_5_0 Thickness of the corneaGlaucoma_cell_1_5_1 NoGlaucoma_cell_1_5_2 YesGlaucoma_cell_1_5_3 The examiner places a pachymeter gently on the front of the eye to measure its thickness.Glaucoma_cell_1_5_4
Nerve fiber analysisGlaucoma_cell_1_6_0 Thickness of the nerve fiber layerGlaucoma_cell_1_6_1 MaybeGlaucoma_cell_1_6_2 MaybeGlaucoma_cell_1_6_3 Using one of several techniques, the nerve fibers are examined.Glaucoma_cell_1_6_4

Glaucoma has been classified into specific types: Glaucoma_sentence_79

Primary glaucoma and its variants Glaucoma_section_8

Primary glaucoma (H40.1-H40.2) Glaucoma_sentence_80

Glaucoma_unordered_list_0

  • Primary open-angle glaucoma, also known as chronic open-angle glaucoma, chronic simple glaucoma, glaucoma simplexGlaucoma_item_0_0

Glaucoma_description_list_1

  • Glaucoma_item_1_1
    • High-tension glaucomaGlaucoma_item_1_2
    • Low-tension glaucomaGlaucoma_item_1_3

Glaucoma_unordered_list_2

  • Primary angle closure glaucoma, also known as primary closed-angle glaucoma, narrow-angle glaucoma, pupil-block glaucoma, acute congestive glaucomaGlaucoma_item_2_4

Glaucoma_description_list_3

  • Glaucoma_item_3_5
    • Acute angle closure glaucoma (aka AACG)Glaucoma_item_3_6
    • Chronic angle closure glaucomaGlaucoma_item_3_7
    • Intermittent angle closure glaucomaGlaucoma_item_3_8
    • Superimposed on chronic open-angle closure glaucoma ("combined mechanism" – uncommon)Glaucoma_item_3_9

Variants of primary glaucoma Glaucoma_sentence_81

Glaucoma_unordered_list_4

Primary angle closure glaucoma is caused by contact between the iris and trabecular meshwork, which in turn obstructs outflow of the aqueous humor from the eye. Glaucoma_sentence_82

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. Glaucoma_sentence_83

In over half of all cases, prolonged contact between iris and TM causes the formation of synechiae (effectively "scars"). Glaucoma_sentence_84

These cause permanent obstruction of aqueous outflow. Glaucoma_sentence_85

In some cases, pressure may rapidly build up in the eye, causing pain and redness (symptomatic, or so-called "acute" angle closure). Glaucoma_sentence_86

In this situation, the vision may become blurred, and halos may be seen around bright lights. Glaucoma_sentence_87

Accompanying symptoms may include a headache and vomiting. Glaucoma_sentence_88

Diagnosis is made from physical signs and symptoms: pupils mid-dilated and unresponsive to light, cornea edematous (cloudy), reduced vision, redness, and pain. Glaucoma_sentence_89

However, the majority of cases are asymptomatic. Glaucoma_sentence_90

Prior to the very severe loss of vision, these cases can only be identified by examination, generally by an eye care professional. Glaucoma_sentence_91

Once any symptoms have been controlled, the first line (and often definitive) treatment is laser iridotomy. Glaucoma_sentence_92

This may be performed using either Nd:YAG or argon lasers, or in some cases by conventional incisional surgery. Glaucoma_sentence_93

The goal of treatment is to reverse and prevent contact between the iris and trabecular meshwork. Glaucoma_sentence_94

In early to moderately advanced cases, iridotomy is successful in opening the angle in around 75% of cases. Glaucoma_sentence_95

In the other 25%, laser iridoplasty, medication (pilocarpine) or incisional surgery may be required. Glaucoma_sentence_96

Primary open-angle glaucoma is when optic nerve damage results in a progressive loss of the visual field. Glaucoma_sentence_97

This is associated with increased pressure in the eye. Glaucoma_sentence_98

Not all people with primary open-angle glaucoma have eye pressure that is elevated beyond normal, but decreasing the eye pressure further has been shown to stop progression even in these cases. Glaucoma_sentence_99

The increased pressure is caused by trabecular meshwork blockage. Glaucoma_sentence_100

Because the microscopic passageways are blocked, the pressure builds up in the eye and causes imperceptible very gradual vision loss. Glaucoma_sentence_101

Peripheral vision is affected first, but eventually the entire vision will be lost if not treated. Glaucoma_sentence_102

Diagnosis is made by looking for cupping of the optic nerve. Glaucoma_sentence_103

Prostaglandin agonists work by opening uveoscleral passageways. Glaucoma_sentence_104

Beta-blockers, such as timolol, work by decreasing aqueous formation. Glaucoma_sentence_105

Carbonic anhydrase inhibitors decrease bicarbonate formation from ciliary processes in the eye, thus decreasing the formation of aqueous humor. Glaucoma_sentence_106

Parasympathetic analogs are drugs that work on the trabecular outflow by opening up the passageway and constricting the pupil. Glaucoma_sentence_107

Alpha 2 agonists (brimonidine, apraclonidine) both decrease fluid production (via inhibition of AC) and increase drainage. Glaucoma_sentence_108

Developmental glaucoma Glaucoma_section_9

Developmental glaucoma (Q15.0) Glaucoma_sentence_109

Glaucoma_unordered_list_5

  • Primary congenital glaucomaGlaucoma_item_5_13
  • Infantile glaucomaGlaucoma_item_5_14
  • Glaucoma associated with hereditary or familial diseasesGlaucoma_item_5_15

Secondary glaucoma Glaucoma_section_10

Secondary glaucoma (H40.3-H40.6) Glaucoma_sentence_110

Glaucoma_unordered_list_6

  • Inflammatory glaucomaGlaucoma_item_6_16

Glaucoma_description_list_7

  • Glaucoma_item_7_17
    • Uveitis of all typesGlaucoma_item_7_18
    • Fuchs heterochromic iridocyclitisGlaucoma_item_7_19

Glaucoma_unordered_list_8

  • Phacogenic glaucomaGlaucoma_item_8_20

Glaucoma_description_list_9

  • Glaucoma_item_9_21
    • Angle-closure glaucoma with mature cataractGlaucoma_item_9_22
    • Phacoanaphylactic glaucoma secondary to rupture of lens capsuleGlaucoma_item_9_23
    • Phacolytic glaucoma due to phacotoxic meshwork blockageGlaucoma_item_9_24
    • Subluxation of lensGlaucoma_item_9_25

Glaucoma_unordered_list_10

  • Glaucoma secondary to intraocular hemorrhageGlaucoma_item_10_26

Glaucoma_description_list_11

  • Glaucoma_item_11_27
    • HyphemaGlaucoma_item_11_28
    • Hemolytic glaucoma, also known as erythroclastic glaucomaGlaucoma_item_11_29

Glaucoma_unordered_list_12

  • Traumatic glaucomaGlaucoma_item_12_30

Glaucoma_description_list_13

  • Glaucoma_item_13_31
    • Angle recession glaucoma: Traumatic recession on anterior chamber angleGlaucoma_item_13_32
    • Postsurgical glaucomaGlaucoma_item_13_33

Glaucoma_unordered_list_14

  • Neovascular glaucoma (see below for more details)Glaucoma_item_14_34
  • Drug-induced glaucomaGlaucoma_item_14_35

Glaucoma_description_list_15

  • Glaucoma_item_15_36
    • Corticosteroid induced glaucomaGlaucoma_item_15_37
    • Alpha-chymotrypsin glaucoma. Postoperative ocular hypertension from use of alpha chymotrypsin.Glaucoma_item_15_38

Glaucoma_unordered_list_16

  • Glaucoma of miscellaneous originGlaucoma_item_16_39

Glaucoma_description_list_17

  • Glaucoma_item_17_40
    • Associated with intraocular tumorsGlaucoma_item_17_41
    • Associated with retinal detachmentsGlaucoma_item_17_42
    • Secondary to severe chemical burns of the eyeGlaucoma_item_17_43
    • Associated with essential iris atrophyGlaucoma_item_17_44
    • Toxic glaucomaGlaucoma_item_17_45

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). Glaucoma_sentence_111

It may also be triggered by other conditions that result in ischemia of the retina or ciliary body. Glaucoma_sentence_112

Individuals with poor blood flow to the eye are highly at risk for this condition. Glaucoma_sentence_113

Neovascular glaucoma results when new, abnormal vessels begin developing in the angle of the eye that begin blocking the drainage. Glaucoma_sentence_114

Patients with such condition begin to rapidly lose their eyesight. Glaucoma_sentence_115

Sometimes, the disease appears very rapidly, especially after cataract surgery procedures. Glaucoma_sentence_116

A new treatment for this disease, as first reported by Kahook and colleagues, involves the use of a novel group of medications known as anti-VEGF agents. Glaucoma_sentence_117

These injectable medications can lead to a dramatic decrease in new vessel formation and, if injected early enough in the disease process, may lead to normalization of intraocular pressure. Glaucoma_sentence_118

Currently, there are no high-quality controlled trials demonstrating a beneficial effect of anti-VEGF treatments in lowering IOP in people with neovascular glaucoma. Glaucoma_sentence_119

Toxic glaucoma is open-angle glaucoma with an unexplained significant rise of intraocular pressure following unknown pathogenesis. Glaucoma_sentence_120

Intraocular pressure can sometimes reach 80 mmHg (11 kPa). Glaucoma_sentence_121

It characteristically manifests as ciliary body inflammation and massive trabecular oedema that sometimes extends to Schlemm's canal. Glaucoma_sentence_122

This condition is differentiated from malignant glaucoma by the presence of a deep and clear anterior chamber and a lack of aqueous misdirection. Glaucoma_sentence_123

Also, the corneal appearance is not as hazy. Glaucoma_sentence_124

A reduction in visual acuity can occur followed neuroretinal breakdown. Glaucoma_sentence_125

Associated factors include inflammation, drugs, trauma and intraocular surgery, including cataract surgery and vitrectomy procedures. Glaucoma_sentence_126

Gede Pardianto (2005) reported on four patients who had toxic glaucoma. Glaucoma_sentence_127

One of them underwent phacoemulsification with small particle nucleus drops. Glaucoma_sentence_128

Some cases can be resolved with some medication, vitrectomy procedures or trabeculectomy. Glaucoma_sentence_129

Valving procedures can give some relief, but further research is required. Glaucoma_sentence_130

Absolute glaucoma Glaucoma_section_11

Absolute glaucoma (H44.5) is the end stage of all types of glaucoma. Glaucoma_sentence_131

The eye has no vision, absence of pupillary light reflex and pupillary response, and has a stony appearance. Glaucoma_sentence_132

Severe pain is present in the eye. Glaucoma_sentence_133

The treatment of absolute glaucoma is a destructive procedure like cyclocryoapplication, cyclophotocoagulation, or injection of 99% alcohol. Glaucoma_sentence_134

Types Glaucoma_section_12

Medication Glaucoma_section_13

Main article: Glaucoma medication Glaucoma_sentence_135

Intraocular pressure can be lowered with medication, usually eye drops. Glaucoma_sentence_136

Several classes of medications are used to treat glaucoma, with several medications in each class. Glaucoma_sentence_137

Each of these medicines may have local and systemic side effects. Glaucoma_sentence_138

Adherence to medication protocol can be confusing and expensive; if side effects occur, the patient must be willing either to tolerate them or to communicate with the treating physician to improve the drug regimen. Glaucoma_sentence_139

Initially, glaucoma drops may reasonably be started in either one or in both eyes. Glaucoma_sentence_140

Wiping the eye with an absorbent pad after the administration of eye drops may result in fewer adverse effects, like the growth of eyelashes and hyperpigmentation in the eyelid. Glaucoma_sentence_141

Poor compliance with medications and follow-up visits is a major reason for vision loss in glaucoma patients. Glaucoma_sentence_142

A 2003 study of patients in an HMO found half failed to fill their prescriptions the first time, and one-quarter failed to refill their prescriptions a second time. Glaucoma_sentence_143

Patient education and communication must be ongoing to sustain successful treatment plans for this lifelong disease with no early symptoms. Glaucoma_sentence_144

The possible neuroprotective effects of various topical and systemic medications are also being investigated. Glaucoma_sentence_145

Glaucoma_unordered_list_18

Laser Glaucoma_section_14

Argon laser trabeculoplasty (ALT) may be used to treat open-angle glaucoma, but this is a temporary solution, not a cure. Glaucoma_sentence_146

A 50-μm argon laser spot is aimed at the trabecular meshwork to stimulate the opening of the mesh to allow more outflow of aqueous fluid. Glaucoma_sentence_147

Usually, half of the angle is treated at a time. Glaucoma_sentence_148

Traditional laser trabeculoplasty uses a thermal argon laser in an argon laser trabeculoplasty procedure. Glaucoma_sentence_149

Nd:YAG laser peripheral iridotomy (LPI) may be used in patients susceptible to or affected by angle closure glaucoma or pigment dispersion syndrome. Glaucoma_sentence_150

During laser iridotomy, laser energy is used to make a small, full-thickness opening in the iris to equalize the pressure between the front and back of the iris, thus correcting any abnormal bulging of the iris. Glaucoma_sentence_151

In people with narrow angles, this can uncover the trabecular meshwork. Glaucoma_sentence_152

In some cases of intermittent or short-term angle closure, this may lower the eye pressure. Glaucoma_sentence_153

Laser iridotomy reduces the risk of developing an attack of acute angle closure. Glaucoma_sentence_154

In most cases, it also reduces the risk of developing chronic angle closure or of adhesions of the iris to the trabecular meshwork. Glaucoma_sentence_155

Diode laser cycloablation lowers IOP by reducing aqueous secretion by destroying secretory ciliary epithelium. Glaucoma_sentence_156

Surgery Glaucoma_section_15

Main article: Glaucoma surgery Glaucoma_sentence_157

Both laser and conventional surgeries are performed to treat glaucoma. Glaucoma_sentence_158

Surgery is the primary therapy for those with congenital glaucoma. Glaucoma_sentence_159

Generally, these operations are a temporary solution, as there is not yet a cure for glaucoma. Glaucoma_sentence_160

Canaloplasty Glaucoma_section_16

Canaloplasty is a nonpenetrating procedure using microcatheter technology. Glaucoma_sentence_161

To perform a canaloplasty, an incision is made into the eye to gain access to the Schlemm's canal in a similar fashion to a viscocanalostomy. Glaucoma_sentence_162

A microcatheter will circumnavigate the canal around the iris, enlarging the main drainage channel and its smaller collector channels through the injection of a sterile, gel-like material called viscoelastic. Glaucoma_sentence_163

The catheter is then removed and a suture is placed within the canal and tightened. Glaucoma_sentence_164

By opening the canal, the pressure inside the eye may be relieved, although the reason is unclear, since the canal (of Schlemm) does not have any significant fluid resistance in glaucoma or healthy eyes. Glaucoma_sentence_165

Long-term results are not available. Glaucoma_sentence_166

Trabeculectomy Glaucoma_section_17

The most common conventional surgery performed for glaucoma is the trabeculectomy. Glaucoma_sentence_167

Here, a partial thickness flap is made in the scleral wall of the eye, and a window opening is made under the flap to remove a portion of the trabecular meshwork. Glaucoma_sentence_168

The scleral flap is then sutured loosely back in place to allow fluid to flow out of the eye through this opening, resulting in lowered intraocular pressure and the formation of a bleb or fluid bubble on the surface of the eye. Glaucoma_sentence_169

Scarring can occur around or over the flap opening, causing it to become less effective or lose effectiveness altogether. Glaucoma_sentence_170

Traditionally, chemotherapeutic adjuvants, such as mitomycin C (MMC) or 5-fluorouracil (5-FU), are applied with soaked sponges on the wound bed to prevent filtering blebs from scarring by inhibiting fibroblast proliferation. Glaucoma_sentence_171

Contemporary alternatives to prevent the scarring of the meshwork opening include the sole or combinative implementation of nonchemotherapeutic adjuvants such as the Ologen collagen matrix, which has been clinically shown to increase the success rates of surgical treatment. Glaucoma_sentence_172

Collagen matrix prevents scarring by randomizing and modulating fibroblast proliferation in addition to mechanically preventing wound contraction and adhesion. Glaucoma_sentence_173

Glaucoma drainage implants Glaucoma_section_18

Main article: Glaucoma valve Glaucoma_sentence_174

The first glaucoma drainage implant was developed in 1966. Glaucoma_sentence_175

Since then, several types of implants have followed on from the original: the Baerveldt tube shunt, or the valved implants, such as the Ahmed glaucoma valve implant or the ExPress Mini Shunt and the later generation pressure ridge Molteno implants. Glaucoma_sentence_176

These are indicated for glaucoma patients not responding to maximal medical therapy, with previous failed guarded filtering surgery (trabeculectomy). Glaucoma_sentence_177

The flow tube is inserted into the anterior chamber of the eye, and the plate is implanted underneath the conjunctiva to allow a flow of aqueous fluid out of the eye into a chamber called a bleb. Glaucoma_sentence_178

Glaucoma_unordered_list_19

  • The first-generation Molteno and other nonvalved implants sometimes require the ligation of the tube until the bleb formed is mildly fibrosed and water-tight. This is done to reduce postoperative hypotony—sudden drops in postoperative intraocular pressure.Glaucoma_item_19_52
  • Valved implants, such as the Ahmed glaucoma valve, attempt to control postoperative hypotony by using a mechanical valve.Glaucoma_item_19_53
  • Ab interno implants, such as the Xen Gel Stent, are transscleral implants by an ab interno procedure to channel aqueous humor into the non-dissected Tenon's space, creating a subconjunctival drainage area similar to a bleb. The implants are transscleral and different from other ab interno implants that do not create a transscleral drainage, such as iStent, CyPass, or Hydrus.Glaucoma_item_19_54

The ongoing scarring over the conjunctival dissipation segment of the shunt may become too thick for the aqueous humor to filter through. Glaucoma_sentence_179

This may require preventive measures using antifibrotic medications, such as 5-fluorouracil or mitomycin-C (during the procedure), or other nonantifibrotic medication methods, such as collagen matrix implant, or biodegradable spacer, or later on create a necessity for revision surgery with the sole or combinative use of donor patch grafts or collagen matrix implant. Glaucoma_sentence_180

And for glaucomatous painful blind eye and some cases of glaucoma, cyclocryotherapy for ciliary body ablation could be considered to be performed. Glaucoma_sentence_181

Laser-assisted nonpenetrating deep sclerectomy Glaucoma_section_19

The most common surgical approach currently used for the treatment of glaucoma is trabeculectomy, in which the sclera is punctured to alleviate intraocular pressure. Glaucoma_sentence_182

Nonpenetrating deep sclerectomy (NPDS) surgery is a similar, but modified, procedure, in which instead of puncturing the scleral bed and trabecular meshwork under a scleral flap, a second deep scleral flap is created, excised, with further procedures of deroofing the Schlemm's canal, upon which, percolation of liquid from the inner eye is achieved and thus alleviating intraocular pressure, without penetrating the eye. Glaucoma_sentence_183

NPDS is demonstrated to have significantly fewer side effects than trabeculectomy. Glaucoma_sentence_184

However, NPDS is performed manually and requires higher level of skills that may be assisted with instruments. Glaucoma_sentence_185

In order to prevent wound adhesion after deep scleral excision and to maintain good filtering results, NPDS as with other non-penetrating procedures is sometimes performed with a variety of biocompatible spacers or devices, such as the Aquaflow collagen wick, ologen Collagen Matrix, or Xenoplast glaucoma implant. Glaucoma_sentence_186

Laser-assisted NPDS is performed with the use of a CO2 laser system. Glaucoma_sentence_187

The laser-based system is self-terminating once the required scleral thickness and adequate drainage of the intraocular fluid have been achieved. Glaucoma_sentence_188

This self-regulation effect is achieved as the CO2 laser essentially stops ablating as soon as it comes in contact with the intraocular percolated liquid, which occurs as soon as the laser reaches the optimal residual intact layer thickness. Glaucoma_sentence_189

Prognosis Glaucoma_section_20

In open-angle glaucoma, the typical progression from normal vision to complete blindness takes about 25 years to 70 years without treatment, depending on the method of estimation used. Glaucoma_sentence_190

The intraocular pressure can also have an effect, with higher pressures reducing the time until blindness. Glaucoma_sentence_191

Epidemiology Glaucoma_section_21

As of 2010, there were 44.7 million people in the world with open angle glaucoma. Glaucoma_sentence_192

The same year, there were 2.8 million people in the United States with open angle glaucoma. Glaucoma_sentence_193

By 2020, the prevalence is projected to increase to 58.6 million worldwide and 3.4 million in the United States. Glaucoma_sentence_194

Both internationally and in the United States, glaucoma is the second-leading cause of blindness. Glaucoma_sentence_195

Globally, cataracts are a more common cause. Glaucoma_sentence_196

Glaucoma is also the leading cause of blindness in African Americans, who have higher rates of primary open-angle glaucoma. Glaucoma_sentence_197

Bilateral vision loss can negatively affect mobility and interfere with driving. Glaucoma_sentence_198

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. Glaucoma_sentence_199

History Glaucoma_section_22

The association of elevated intraocular pressure (IOP) and glaucoma was first described by Englishman Richard Bannister in 1622: "...that the Eye be grown more solid and hard, then naturally it should be...". Glaucoma_sentence_200

Angle-closure glaucoma was treated with cataract extraction by John Collins Warren in Boston as early as 1806. Glaucoma_sentence_201

The invention of the ophthalmoscope by Hermann Helmholtz in 1851 enabled ophthalmologists for the first time to identify the pathological hallmark of glaucoma, the excavation of the optic nerve head due to retinal ganglion cell loss. Glaucoma_sentence_202

The first reliable instrument to measure intraocular pressure was invented by Norwegian ophthalmologist Hjalmar August Schiøtz in 1905. Glaucoma_sentence_203

About half a century later, Hans Goldmann in Berne, Switzerland, developed his applanation tonometer which still today - despite numerous new innovations in diagnostics - is considered the gold standard of determining this crucial pathogenic factor. Glaucoma_sentence_204

In the late 20th century, further pathomechanisms beyond elevated IOP were discovered and became the subject of research like insufficient blood supply – often associated with low or irregular blood pressure – to the retina and optic nerve head. Glaucoma_sentence_205

The first drug to reduce IOP, pilocarpine, was introduced in the 1870s; other major innovations in pharmacological glaucoma therapy were the introduction of beta blocker eye drops in the 1970s and of prostaglandin analogues and topical (locally administered) carbonic anhydrase inhibitors in the mid-1990s.. Glaucoma_sentence_206

Early surgical techniques like iridectomy and fistulating methods have recently been supplemented by less invasive procedures like small implants, a range of options now widely called MIGS (micro-invasive glaucoma surgery). Glaucoma_sentence_207

Etymology Glaucoma_section_23

The word "glaucoma" comes from the Ancient Greek γλαύκωμα, a derivative of γλαυκóς, which commonly described the color of eyes which were not dark (i.e. blue, green, light gray). Glaucoma_sentence_208

Eyes described as γλαυκóς due to disease might have had a gray cataract in the Hippocratic era, or, in the early Common Era, the greenish pupillary hue sometimes seen in angle-closure glaucoma. Glaucoma_sentence_209

Research Glaucoma_section_24

Rho kinase inhibitors Glaucoma_section_25

Rho kinase inhibitors, such as ripasudil, work by inhibition of the actin cytoskeleton, resulting in the morphological changes in the trabecular meshwork and increased aqueous outflow. Glaucoma_sentence_210

More compounds in this class are being investigated in phase 2 and phase 3 trials. Glaucoma_sentence_211

Neuroprotective agents Glaucoma_section_26

A 2013 Cochrane Systematic Review compared the effect of brimonidine and timolol in slowing the progression of open angle glaucoma in adult participants. Glaucoma_sentence_212

The results showed that participants assigned to brimonidine showed less visual field progression than those assigned to timolol, though the results were not significant, given the heavy loss-to-followup and limited evidence. Glaucoma_sentence_213

The mean intraocular pressures for both groups were similar. Glaucoma_sentence_214

Participants in the brimonidine group had a higher occurrence of side effects caused by medication than participants in the timolol group. Glaucoma_sentence_215

Cannabis Glaucoma_section_27

Studies in the 1970s reported that the use of cannabis may lower intraocular pressure. Glaucoma_sentence_216

In an effort to determine whether marijuana, or drugs derived from it, might be effective as a glaucoma treatment, the US National Eye Institute supported research studies from 1978 to 1984. Glaucoma_sentence_217

These studies demonstrated some derivatives of marijuana lowered intraocular pressure when administered orally, intravenously, or by smoking, but not when topically applied to the eye. Glaucoma_sentence_218

In 2003, the American Academy of Ophthalmology released a position statement stating that cannabis was not more effective than prescription medications. Glaucoma_sentence_219

Furthermore, no scientific evidence has been found that demonstrates increased benefits and/or diminished risks of cannabis use to treat glaucoma compared with the wide variety of pharmaceutical agents now available. Glaucoma_sentence_220

In 2010 the American Glaucoma Society published a position paper discrediting the use of cannabis as a legitimate treatment for elevated intraocular pressure, for reasons including short duration of action and side effects that limit many activities of daily living. Glaucoma_sentence_221


Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Glaucoma.