Glaucoma risk factors, risk factors of glaucoma

Glaucoma risk factors, risk factors of glaucoma

Glaucoma risk factors

Glaucoma risk factors

Glaucoma risk factors

Over many years, glaucoma has been defined by an intraocular pressure of more than 20 or 20 mm Hg.

Incompatible with this (now obsolete) definition of glaucoma was the ever larger number of cases that have been reported in medical literature in the 1980s and 1990s who had the typical signs of glaucomatous damage, like optic nerve head excavation and thinning of the retinal nerve fiber layer, while these patients had an IOP that would generally have been regarded as “normal”.

It is now widely estimated that a larger percentage of patients with primary open-angle glaucoma (POAG) are suffering form from normal tension glaucoma: probably half of all POAG patients in Europe and the majority of POAG patients in East Asia.

Among Americans of Japanese descent, for instance, the prevalence of NTG is about four times as high as the prevalence of the “classical glaucoma” with an IOP of 22 mm Hg and higher.

The pillar of the current understanding of normal tension glaucoma is a reduced IOP tolerance of the retinal ganglion cells and the cells in the optic nerve head – an IOP of, for example, 17 or 19 mm Hg that would not affect a healthy eye leads to damage in the eye of an NTG patient.[1]

Risk factors[edit]

In many patients, normal tension glaucoma is common in individuals with a generalized reduced perfusion of organs and certain body tissues.

A low blood pressure – whether consistently low or with sudden pressure drops – is associated with NTG as are conditions like Flammer syndrome and obstructive sleep apnea.[2]

Flammer syndrome has been attributed to increase the likelihood of ganglion cell damage in normal tension glaucoma patients with disc hemorrhages as a characteristic clinical sign. [3] Besides race (Japanese) and low blood pressure, the female gender is also a risk factor.[4]

Diagnosis[edit]

While tonometry, the measuring of IOP and thus a classical instrument in the diagnosis of glaucoma, is not helpful, ophthalmoscopy leads to the diagnosis by showing typical glaucomatous damage, primarily at the optic nerve head, in the absence of elevated IOP.

While the excavation of the optic nerve head and the thinning of its rim appear in all kinds of glaucoma (with high tension and with normal tension, in POAG and in secondary glaucoma), small hemorrhages close to the optic disc have been identified as a characteristic clinical sign of normal tension glaucoma.

Since NTG is closely linked to vascular irregularities, a medical check-up by a general practitioner or a specialist in internal medicine is widely recommended in cases of newly diagnosed normal tension glaucoma.

An examination that is considered to be of particular importance is a 24-hour monitoring of the blood pressure.[5] NTG patients tend to suffer “dips”, sudden and unnoticed drops in blood pressure during sleep.

RISK FACTORS

It is estimated that nearly 4 million Americans have glaucoma, but only half of those who have it know it. This number is only expected to rise with the aging of our population. While everyone is at risk for glaucoma, there are

  • Positive family history of glaucoma within immediate familyeye-health-1___Source
  • Aging (Individuals over 40 years of age)
  • Gender (Male)
  • Race (African Americans)
  • High eye pressure
  • Pain or redness in the eyes
  • High Myopia (Near sightedness)
  • Diabetes
  • Hypertension
  • Sleep-Disordered breathing
  • History of steroid use
  • Eye Injury or surgery

People at high risk for glaucoma should get a complete eye exam, including eye dilation, every one or two years. Everyone over 40 should have a comprehensive eye examination every two years, regardless of risk factors.

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