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For further information, see CMDT Part 7-11: Chronic Glaucoma

Key Features

Essentials of Diagnosis

  • Three types of chronic glaucoma: open-angle glaucoma, angle-closure glaucoma, and normal tension glaucoma

  • No symptoms in early stages

  • Insidious progressive bilateral loss of peripheral vision, resulting in tunnel vision; visual acuities preserved until advanced disease

  • Pathologic cupping of the optic disks

  • Intraocular pressure is usually elevated

General Considerations

  • Characterized by gradually progressive excavation ("cupping") of the optic disk with loss of vision progressing from slight visual field loss to complete blindness

  • Chronic open-angle glaucoma

    • Intraocular pressure is elevated due to reduced drainage of aqueous fluid through the trabecular meshwork

    • Secondary open-angle glaucoma may result from

      • Ocular disease (eg, pigment dispersion, pseudoexfoliation, uveitis)

      • Trauma

      • Corticosteroid therapy, whether it is intraocular, topical, inhaled, intranasal, or systemic

  • Chronic angle-closure glaucoma

    • Particularly common in Inuits and eastern Asians

    • Flow of aqueous fluid into the anterior chamber angle is obstructed

  • Normal-tension glaucoma

    • Intraocular pressure is not elevated

    • However, same pattern of optic nerve damage occurs

Demographics

  • Prevalence is increased in first-degree relatives of affected individuals and in diabetic patients

  • In Afro-Caribbean and African persons, and probably in Hispanic persons, it is more frequent, occurs at an earlier age, and results in more severe optic nerve damage

  • In the United States,

    • An estimated 2% of people over 40 years of age have glaucoma, affecting over 2.5 million individuals

    • At least 25% of cases are undetected

    • Over 90% of cases are of the open-angle type

  • Worldwide

    • Open-angle glaucoma: about 45 million people are affected, of whom about 4.5 million are bilaterally blind

    • Chronic angle-closure glaucoma: about 4 million people are bilaterally blind, of whom approximately 50% live in China

Clinical Findings

  • Primary (chronic) open-angle glaucoma is usually bilateral

  • Optic disk cupping

    • Identified as an absolute increase or an asymmetry between the two eyes of the ratio of the diameter of the optic cup to the diameter of the whole optic disk (cup-disk ratio)

    • Cup-disk ratio > 0.5 or asymmetry between eyes of 0.2 or more suggests glaucoma

  • Visual field abnormalities

    • Initially develop in the paracentral region, followed by constriction of the peripheral visual field

    • Central vision remains good until late in the disease

  • Intraocular pressure

    • Normal range is 10–21 mm Hg

    • Elevated intraocular pressure is not associated with optic disk or visual field abnormalities (ocular hypertension) in many individuals (about 4.5 million in the United States)

    • In primary open-angle glaucoma, intraocular pressure is often normal when it is first measured, and only repeated measurements identify the abnormally high pressure

Diagnosis

  • Initially, there are no symptoms

  • Often first suspected at a routine eye test

  • Diagnosis requires consistent and reproducible abnormalities in at least two of three parameters

    • Optic disk or retinal nerve fiber layer (or both)

    • Visual ...

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