History and exam

Key diagnostic factors

common

presence of risk factors

Key risk factors include intra-ocular pressure >21 mmHg, age >50 years, family history of glaucoma, and black or Hispanic ethnicity.

cup-to-disc ratio >0.5

Increasing cup-to-disc ratio is associated with increased risk for developing open-angle glaucoma.[39][40]

A ratio of 0.7 may be a normal anatomical variant, while a ratio of 0.3 may indicate glaucoma if the ratio started at 0.1. Therefore, the change in cup-to-disc ratio is significant when determining damage.

Documenting an increase in cup-to-disc ratio is more meaningful than a cup-to-disc ratio determined at a single visit.​[1][13]​​[Figure caption and citation for the preceding image starts]: Photograph showing optic disc cupping. An increase in cup-to-disc ratio over time may indicate glaucoma.Collection of Robert B. Avery, MD, PhD [Citation ends].com.bmj.content.model.Caption@1d6fb687[Figure caption and citation for the preceding image starts]: Fundus photograph of normal optic nerve headCollection of Robert B. Avery, MD, PhD [Citation ends].com.bmj.content.model.Caption@755e1337

notching of optic nerve cup

Good sensitivity and positive predictive value for glaucoma.​[41]

symptomatic peripheral vision loss

Shown by missing areas in the field of vision (corresponding to disc appearances) in the absence of other identifiable causes, such as retinal detachment or strokes involving the visual pathways.

Indicates advanced disease.[13]​ Characteristic patterns of field loss in glaucoma include nasal defects or arcuate loss, often respecting the horizontal midline.

increased intra-ocular pressure

Common, but some patients may have a normal measurement at the time of diagnosis.[42]

scotomas

Found on visual field testing.

loss of nerve fibre layer

Used as a diagnostic factor (e.g., by optical coherence tomography).[13]

uncommon

optic disc haemorrhage

Appears on, or adjacent to, the optic nerve. Associated with normal-tension glaucoma.

Other diagnostic factors

common

corneal hysteresis

Generally low in glaucoma. Lower values may be associated with an increased risk of glaucoma progression.[29]​ Equipment is not widely available at present.

Risk factors

strong

intra-ocular pressure >21 mmHg

Well known to increase glaucomatous damage.[13]​ ​Whenever possible, assess corneal thickness at the same time.

Deformation and stress to the lamina cribrosa may impair axoplasmic flow in retinal ganglion cells.[1]​​

age >50 years

Incidence increases with age, with most glaucoma diagnosed in patients older than 50 years.[13][14]

family history of glaucoma

First-degree family history of glaucoma increases risk for glaucoma by approximately 7-9 times that of the general population.[20][21][22]

genetic abnormalities

Mutations in the myocilin gene, which are present in 2% to 4% of patients with primary open-angle glaucoma, can lead to early-onset glaucoma and very high intra-ocular pressures.[13]​ Somatic mutations within myocilin may also accumulate with age and contribute to an increased risk for glaucoma.[16]

Glaucoma is a complex polygenic disease with multiple abnormalities reported in genes and novel single nucleotide polymorphisms.[23]

black ethnicity or Hispanic ethnicity

Prevalence of open-angle glaucoma is threefold higher in African-American and Hispanic people of Mexican ancestry compared with non-Hispanic white people.[8][11]​​[12]

myopia

A 3.3-times greater risk of glaucoma is reported in people with more than -3 dioptres of myopia.[13]

Risk is even higher in patients who have a refractive error of more than -6 dioptres.[15]

weak

diabetes mellitus

Meta-analyses of data from observational studies suggest that diabetes mellitus may increase risk for open-angle glaucoma.​[24][25][26]​​​

hypertension

Higher prevalence in patients with glaucoma.[27]

low ocular perfusion pressure

Risk of glaucoma may be increased risk in patients with either low diastolic (<50 mmHg) or low systolic (≤125 mmHg) perfusion pressure.[28]

thin central corneal thickness

Thin central corneal thickness is associated with higher progression rate from ocular hypertension to glaucoma, and a higher risk of glaucoma progression.[29]

corneal hysteresis

Corneal hysteresis refers to the corneal response to transient compression and release by an air-puff tonometer (i.e., the difference between the initial and rebound applanation pressure). Values may be lower in glaucoma, and lower values may be associated with an increased risk of glaucoma progression.[29]

calcium-channel blockers

Calcium-channel blocker use may modulate the risk of developing open-angle glaucoma.[30] One population-based cross-sectional study found that use may be associated with the development of glaucoma; a causal relationship has not been established.[31]​​

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