Open Angle Glaucoma

Aka: Open Angle Glaucoma, Primary Open-Angle Glaucoma, POAG

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II. Epidemiology

  1. Most common type of Glaucoma (89%)
  2. Lifetime Prevalence: 10% of U.S. population (50% are unaware of diagnosis)
  3. More common in older patients
    1. Rare under age 40 years
    2. Prevalence among those over 80 years old: 14%
    3. However most undiagnosed Glaucoma is at age <60 years old

III. Risk Factors

  1. Increasing age
    1. Odds Ratio increases 1.6 to 2.2 per decade of life
    2. Prevalence at age 40-49 years old
      1. Black: 1.3 to 1.4%
      2. Hispanic: 0.5 to 1.3%
      3. Caucasian: 0.2 to 0.5%
    3. Prevalence at age >80 years old
      1. Black: 11.3 to 23.2%
      2. Hispanic: 12.6 to 21.8%
      3. Caucasian: 1.9 to 11.4%
  2. Ethnicity or Race
    1. See age related Prevalence above
    2. Black patients
      1. Relative Risk: 3.5 to 4 fold increase in Glaucoma risk over caucasian patients
    3. Hispanic Patients
      1. Relative Risk: 2 fold increase in Glaucoma risk over caucasian patients
  3. First Degree Relative with Glaucoma (4-16% Risk)
    1. Sibling Relative Risk: 3.7 to 16
    2. Child or parent Relative Risk: 1.1 to 2.2
    3. Specific Glaucoma related genetic mutation accounts for <5% of cases
  4. Ocular predisposition
    1. Severe Myopia (Nearsightedness)
    2. Thin central Cornea
  5. Eye Injury
    1. Eye Trauma
    2. Uveitis
    3. Corticosteroids (especially intra- and periocular)

IV. Associated Conditions

  1. Endocrine
    1. Diabetes Mellitus
      1. Glaucoma Relative Risk: 1.4 to 1.5
    2. Hypothyroidism
    3. Cushing Disease
  2. Cardiopulmonary
    1. Obstructive Sleep Apnea
    2. Cardiovascular Disease
  3. Hematologic
    1. Sickle Cell Disease
  4. Inflammatory and Infectious conditions
    1. Herpetic infections
    2. Lyme Disease
    3. Rheumatoid Arthritis
    4. Sarcoidosis
    5. Systemic Lupus Erythematosus
  5. Miscellaneous
    1. Aggressive Blood Pressure lowering

V. Pathophysiology

  1. Increased Aqueous Humor production
  2. Aqueous outflow obstruction by microscopic blockages
  3. Normal chamber angles (contrast with Narrow Angle Glaucoma)
  4. Increased introcular pressure progressively compresses the Optic Nerve Heads and injures the Retinal axons
    1. Vascular theory suggests an ischemic injury mechanism
    2. Neurodegenerative theory suggests Autoimmunity or failed nerve repair mechanisms

VI. Symptoms

  1. Bilateral eyes affected but asymmetrically
  2. Colored halos around lights
  3. Reduced contrast sensitivity
    1. Decreased ability to distinguish small objects against their background
  4. Asymptomatic until severe Visual Field or central loss
    1. Visual Field loss irreversible unless caught early
    2. Compensation from opposite eye masks earlier visual changes
    3. Insidious painless Vision Loss
      1. Gradual blind spot development
      2. Peripheral Vision Loss progresses to blindness
      3. Loss not symptomatic until 40% of nerve fibers lost

VII. Signs

  1. Pupil dilatation
  2. Increased Intraocular Pressure (by Tonometer)
    1. IOP < 22 mmHg: Normal if Optic Disks normal
    2. IOP 22-30 mmHg: Borderline
    3. IOP >31 mmHg: Abnormal
  3. Progressive peripheral Vision Loss
    1. Visual Field changes do not occur until 50% of Retinal pigment cells are lost
    2. Stages of Vision Loss
      1. Stage 1: Loss of nasal and superior Visual Field
      2. Stage 2: Loss of peripheral Visual Field
      3. Stage 3: Total blindness
    3. Methods
      1. Screen Visual Fields by confrontation
      2. Perimetry
        1. Computerized Visual Field evaluation
  4. Glaucoma-Related changes in the Optic Disc
    1. General
      1. Optic Cup becomes more prominent (cupping) as the Neuroretinal Rim thins
      2. Focal thinning of Neuroretinal Rim
        1. Nerves at edge of cup and edge of disc
        2. Thinning may be most prominent at temporal (lateral) disc margin
        3. Thinning may be asymmetric with "notching" at regions of thinning
      3. Superficial Hemorrhage overlying disc edge
    2. Diagnostic changes
      1. Symmetrically enlarged cup-to-disc ratio >0.3 to 0.5 or
      2. Cup-to-disc ratio difference between eyes >0.2 or
      3. Significantly asymmetric cup in one eye

VIII. Diagnosis

  1. Formal Open Angle Glaucoma diagnosis requires a combination of findings
    1. IOP measurement
    2. Stereoscopic Optic Nerve exam
    3. Visual Field testing
  2. Intraocular Pressure alone is not sufficient for diagnosis
    1. Optic Disc changes and Visual Field Deficits may be present without IOP increase on initial presentation
    2. Normal Intraocular Pressure in 40-50% of POAG at time of diagnosis
      1. A single value may be insufficient to exclude Ocular Hypertension (IOP is lower in the evening)
    3. Most patients with Intraocular Pressure >21 mm Hg do not develop Glaucoma (with Optic Nerve injury)
      1. Elevated Intraocular Pressure results in Glaucoma in 10% at 5 years and 30% at 20 years
    4. Screening is not recommended to be performed in primary care (USPTF)
      1. Combination of factors needed for diagnosis (see signs above)
      2. Typically performed by eye specialists
  3. Other testing performed by Ophthalmology
    1. Pachymetry (Corneal thickness measurement)
    2. Gonioscopy (anterior chamber angle)
    3. Optical Coherance Tomography (OCT)
      1. Evaluates Optic Nerve Head anatomy by analyzing reflected light off the Optic Disc
      2. Neuroretinal Rim thinning identified on serial OCT evaluations often precedes Visual Field Deficits

IX. Differential Diagnosis

  1. Acute Angle Closure Glaucoma
    1. Presents as a painful Red Eye
    2. Requires immediate evaluation and management
  2. Optic Neuropathy
    1. Ischemic Optic Neuritis
    2. Retrobulbar Optic Neuropathy (Multiple Sclerosis)

X. Management

  1. Precautions
    1. Diagnosis of Glaucoma is often unclear early in the course
    2. Serial, longterm periodic Eye Exams by ophthalmology are required
  2. Decision for ophthalmologists to start medications is based on multiple factors
    1. Optic Nerve and Optic Disc status
    2. Normal Intraocular Pressure may still warrant medication management to lower IOP
      1. Glaucoma related changes (e.g. Optic Cupping, peripheral field deficit) should be treated
      2. Rate of IOP increase may indicate starting medications more than the absolute IOP measurement
    3. Ocular Hypertension associated risk of Glaucoma
      1. https://ohts.wustl.edu/risk/
      2. Increased Intraocular Pressure alone is not always an indication to start medications
  3. General
    1. Regular aerobic Exercise reduces Intraocular Pressure
    2. Emphasize Medication Compliance (<50% continue medications >1 year)
      1. Simplify regimens as much as possible
      2. Review barriers with patients (e.g. cost, adverse effects)
      3. Consider generic, inexpensive alternative medications for patients for whom cost is a barrier
    3. Approach treatment in similar fashion to systemic Hypertension Management
      1. Start with initial first-line agents
      2. Advance first-line agents
      3. Add additional medications as needed for persistent elevated pressures
  4. First Line Agents
    1. Prostaglandin Analogues (Latanoprost, Travoprost, Bimatoprost, Tafluprost, Unoprostone)
      1. Increases uveoscleral aqueous outflow (lowers IOP 25 to 35%)
      2. Once daily, effective agent with low side effects
      3. Latanoprost (Xalatan) 0.005% one drop daily
    2. Intraocular Beta Blockers (Betaxolol, Carteolol, Levobunolol, Metipranolol, Timolol)
      1. Decrease Aqueous Humor production (lowers IOP 20-25%)
      2. Less expensive than other Glaucoma medications
      3. Consider other medications if higher risk for adverse effects
        1. Systemic Beta Blocker use
        2. Beta Blockers otherwise contraindicated (e.g. COPD, Asthma)
      4. More adverse effects
        1. Due to Beta Blocker systemic absorption with Hypotension and bronchoconstriction risk
        2. See Don't Open Eyes Technique for Eye Drop Instillation (to reduce systemic absorption)
  5. Second Line Agents
    1. Intraocular Cholinergics (Pilocarpine, Carbachol)
      1. Increase aqueous outflow (lowers IOP 20 to 30%)
  6. Adjunctive Agents
    1. Intraocular Sympathomimetic (Dipivefrin, Propine)
    2. Topical Carbonic Anhydrase Inhibitor (Brinzolamide, Dorzolamide)
      1. Decrease aqueous production (lowers IOP 15-20%)
    3. Intraocular Alpha-Adrenergic (Apraclonidine, Brimonidine)
      1. Decrease aqueous production and increase aqueous outflow (lowers IOP 20 to 25%)
  7. Acute exacerbations of refractory chronic Glaucoma
    1. Systemic Carbonic Anhydrase Inhibitor
  8. Combination agents to consider
    1. Dorzolamide and Timolol Maleate (Cosopt, generic)
    2. Brinzolamide and Brimonidine (Simbrinza, expensive)
    3. Brimonidine and Timolol (Combigen, expensive)
  9. New novel medications
    1. Latanoprostene (Vyzulta)
    2. Netarsudil (Rhopressa)
      1. Rho-Kinase Inhibitor lowers Episcleral venous pressures and increases aqueous outflow (lowers IOP 10 to 20%)
  10. Surgery for refractory cases
    1. Selective Laser trabeculoplasty (SLT)
      1. Increases permeability of the trabecular meshwork, reducing resistance to aqueous outflow to venous system
      2. May be used as first line therapy (esp. for patients non-compliant with topical drops)
      3. When compared with Topical Medications, SLT had better outcomes, and 75% no longer needed Topical Medications
      4. Gazzard (2019) Lancet 393(10180): 1505-16 [PubMed]
    2. Surgical trabeculectomy
      1. Small incision made in Sclera to increase aqueous fluid drainage
      2. Higher risk procedure used as last available option

XI. Prevention

  1. See Preventive Eye Examination for Glaucoma screening intervals
  2. Glaucoma Screening Indications
    1. USPTF does not recommend routine screening for Glaucoma in the general adult population
    2. U.S. Centers for Medicare and Medicaid (CMS) covers eye care professional exams for high risk conditions
      1. Diabetes Mellitus
      2. Family History of Glaucoma
      3. African Descent (age over 50 years)
      4. Hispanic Descent (age over 64 years)
    3. Eyecare America (AAO sponsored)
      1. https://www.aao.org/eyecare-america
      2. No cost Glaucoma exams and follow-up for patients at moderate to high risk for developing Glaucoma

XII. Complications

  1. Blindness
    1. Without treatment, POAG progresses from normal Vision to blindness over 25 years
    2. More than half of patients are asymptomatic, as peripheral Vision Loss goes unnoticed until severe

XIII. References

  1. Alward (1998) N Engl J Med 339:1298-307 [PubMed]
  2. Distelhorst (2003) Am Fam Physician 67(9):1937-50 [PubMed]
  3. Gupta (2016) Am Fam Physician 93(8):668-74 [PubMed]
  4. Infeld (1998) Postgrad Med 74:709-15 [PubMed]
  5. Michels (2023) Am Fam Physician 107(3): 253-62 [PubMed]
  6. Pelletier (2016) Am Fam Physician 94(3):219-26 [PubMed]

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Related Studies

Ontology: Glaucoma, Open-Angle (C0017612)

Definition (MSH) Glaucoma in which the angle of the anterior chamber is open and the trabecular meshwork does not encroach on the base of the iris.
Concepts Disease or Syndrome (T047)
MSH D005902
ICD9 365.10, 365.13, 365.1
ICD10 H40.1 , H40.13, H40.10
SnomedCT 193539001, 193538009, 193543002, 46168003, 111513000, 84494001
English Compensated Glaucoma, Compensated Glaucomas, Compensative Glaucoma, Compensative Glaucomas, Glaucoma Simplex, Glaucoma, Compensated, Glaucoma, Compensative, Glaucoma, Open Angle, Glaucoma, Pigmentary, Glaucoma, Simple, Glaucomas, Compensated, Glaucomas, Compensative, Glaucomas, Open Angle, Glaucomas, Open-Angle, Glaucomas, Pigmentary, Glaucomas, Simple, Open Angle Glaucomas, Open-Angle Glaucoma, Open-Angle Glaucomas, Pigmentary Glaucomas, Simple Glaucoma, Simple Glaucomas, Simplex, Glaucoma, Simplices, Glaucoma, Pigmentary Glaucoma, Open-angle glaucoma unspecif., Open-angle glaucoma, unspecified, open-angle glaucoma, open-angle glaucoma (diagnosis), glaucoma open-angle, pigmentary glaucoma (diagnosis), pigmentary open-angle glaucoma (diagnosis), secondary pigmentary open-angle glaucoma, pigmentary glaucoma, pigmentary open-angle glaucoma, Open angle glaucoma NOS, Open-angle glaucoma NOS, Glaucoma, Open-Angle [Disease/Finding], glaucoma pigmentary, open angle glaucoma, glaucoma simple, angle glaucoma open, simplex glaucoma, wide-angle glaucoma, pigment dispersion syndrome, Glaucoma, Open-Angle, Unspecified open-angle glaucoma, Glaucoma, open-angle, Pigmentary open-angle glaucoma, Unspecified open-angle glaucoma (disorder), Open-angle glaucoma NOS (disorder), Pigmentary glaucoma, Glaucoma simplex, Open-angle glaucoma, Open cleft glaucoma, Open-angle glaucoma (disorder), Pigmentary glaucoma (disorder), Wide-angle glaucoma, glaucoma; noncongestive, glaucoma; open-angle, glaucoma; pigmentary, glaucoma; simple, noncongestive; glaucoma, pigmentary; glaucoma, simple; glaucoma, Open-angle glaucoma, NOS, Wide-angle glaucoma, NOS, Open Angle Glaucoma, Wide-angle glaucoma NOS, Open angle glaucoma, OAG - Open-angle glaucoma
Dutch open-kamerhoek-glaucoom NAO, niet-gespecificeerd open-kamerhoek-glaucoom, glaucoma simplex, glaucoom; niet-congestief, glaucoom; open kamerhoek, glaucoom; pigment-dispersie, glaucoom; simplex, niet-congestief; glaucoom, pigment-dispersie; glaucoom, simplex; glaucoom, open-kamerhoek-glaucoom, pigmentair glaucoom, Glaucoma simplex, Glaucoom, eenvoudig, Glaucoom, gepigmenteerd, Glaucoom, openhoek-, Openhoekglaucoom
French Glaucome à angle ouvert SAI, Glaucome à angle ouvert, non précisé, Glaucome à angle ouvert, Glaucome pigmentaire, Glaucome chronique simple, Glaucome chronique à angle ouvert, Glaucome simple
German Weitwinkelglaukom NNB, Weitwinkelglaukom, unspezifisch, Glaukom pigmentiert, Weitwinkelglaukom, Glaucoma simplex, Glaukom, Pigment-, Glaukom, Weitwinkel-, Glaukom, einfaches, Offenwinkelglaukom
Italian Glaucoma ad angolo aperto NAS, Glaucoma ad angolo aperto, non specificato, Glaucoma pigmentario, Glaucoma compensato, Glaucoma semplice, Glaucoma simplex, Glaucoma ad angolo aperto
Portuguese Glaucoma de ângulo aberto NE, Glaucoma simplex, Glaucoma pigmentar, Glaucoma de ângulo aberto, Glaucoma de Ângulo Aberto, Glaucoma Pigmentar, Glaucoma Simples
Spanish Glaucoma de ángulo abierto NEOM, Glaucoma de ángulo abierto no especificado, glaucoma de fisura abierta, glaucoma de ángulo amplio, Glaucoma simple, glaucoma de ángulo abierto, SAI (trastorno), glaucoma de ángulo abierto, no especificado (trastorno), glaucoma de ángulo abierto, no especificado, glaucoma de ángulo abierto, SAI, glaucoma de ángulo abierto (trastorno), glaucoma de ángulo abierto, glaucoma pigmentario (trastorno), glaucoma pigmentario, glaucoma simple, Glaucoma pigmentario, Glaucoma de ángulo abierto, Glaucoma de Ángulo Abierto, Glaucoma Pigmentario, Glaucoma Simple
Japanese 開放隅角緑内障ＮＯＳ, 開放隅角緑内障、詳細不明, ｼｷｿｾｲﾘｮｸﾅｲｼｮｳ, ｶｲﾎｳｸﾞｳｶｸﾘｮｸﾅｲｼｮｳNOS, ｶｲﾎｳｸﾞｳｶｸﾘｮｸﾅｲｼｮｳｼｮｳｻｲﾌﾒｲ, ｶｲﾎｳｸﾞｳｶｸﾘｮｸﾅｲｼｮｳ, 開放角緑内障, 緑内障-開放隅角, ﾀﾝｾｲﾘｮｸﾅｲｼｮｳ, 単性緑内障, 単純緑内障, 色素性緑内障, 開放隅角緑内障, 緑内障-単性, 緑内障-単純, 緑内障-色素性, 緑内障-開放角
Swedish Öppenvinkelglaukom
Czech glaukom s otevřeným úhlem, Glaukom otevřeného úhlu, Glaukom otevřeného úhlu NOS, Blíže neurčený glaukom otevřeného úhlu, Pigmentový glaukom, Glaucoma simplex, pigmentový glaukom, syndrom pigmentové disperze
Finnish Avokulmaglaukooma
Russian GLAUKOMA PIGMENTNAIA, GLAUKOMA KHRONICHESKAIA, GLAUKOMA OTKRYTOUGOL'NAIA, GLAUKOMA PROSTAIA, ГЛАУКОМА ОТКРЫТОУГОЛЬНАЯ, ГЛАУКОМА ПИГМЕНТНАЯ, ГЛАУКОМА ПРОСТАЯ, ГЛАУКОМА ХРОНИЧЕСКАЯ
Croatian GLAUKOM OTVORENOG KUTA
Polish Jaskra z otwartym kątem przesączania, Jaskra otwartego kąta
Hungarian Nyíltzugú glaucoma, Nyíltzúgú glaucoma k.m.n., Pigment glaucoma, Nyíltzúgú glaucoma, nem meghatározott, Nyíltzúgú glaucoma, Glaucoma simplex
Norwegian Pigmentert glaukom, Pigmentglaukom, Kompensert galukom, Åpenvinkelglaukom, Simpleksglaukom
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Glaucoma, Primary Open Angle (C0339573)

Concepts Disease or Syndrome (T047)
MSH C562750
ICD9 365.11
ICD10 H40.1 , H40.11
SnomedCT 155122001, 77075001
English COAG-Chronic open-angle glauc, POAG-Primary open-angle glauc, GLAUCOMA, PRIMARY OPEN ANGLE, POAG, glaucoma open-angle primary, primary open-angle glaucoma (diagnosis), primary open-angle glaucoma, Prim open angle glaucoma, chronic simple glaucoma, simple chronic glaucoma, primary open angle glaucoma, Glaucoma, Primary Open Angle, Primary open-angle glaucoma (disorder), Primary open angle glaucoma, Chronic simple glaucoma, COAG - Chronic open-angle glaucoma, CSG - Chronic simple glaucoma, POAG - Primary open-angle glaucoma, Primary open-angle glaucoma, Primary open angle glaucoma (disorder), chronic; glaucoma, simple, glaucoma; chronic, simple, Primary Open Angle Glaucoma
Dutch primair open-kamerhoek-glaucoom, chronisch; glaucoom, simplex, glaucoom; chronisch, simplex, Primair open-kamerhoekglaucoom
French Glaucome primitif à angle ouvert
German primaeres Weitwinkelglaukom, Primaeres Weitwinkelglaukom
Italian Glaucoma primario ad angolo aperto
Portuguese Glaucoma de ângulo aberto primário
Spanish Glaucoma de ángulo abierto primario, glaucoma primario de ángulo abierto (trastorno), glaucoma primario de ángulo abierto, glaucoma simple crónico
Japanese 原発性開放隅角緑内障, ｹﾞﾝﾊﾟﾂｾｲｶｲﾎｳｸﾞｳｶｸﾘｮｸﾅｲｼｮｳ
Czech Primární glaukom otevřeného úhlu
Korean 원발성 개방우각 녹내장
Hungarian Elsődleges nyíltzugú glaucoma
Derived from the NIH UMLS (Unified Medical Language System)

Related Topics in Glaucoma

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