Glaucoma risk factors: Intraocular pressure

Nils A. Loewen*, Angelo P. Tanna

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter

1 Scopus citations


Intraocular pressure is a major risk factor for the development of glaucoma. It remains an important parameter in the diagnosis – and the only proven means to reduce the risk of progression – and the treatment of glaucoma. Randomized clinical trials, most notably the Ocular Hypertension Treatment Study (OHTS) and Early Manifest Glaucoma Trial (EMGT), have established the protective role of lowering IOP in preventing conversion from ocular hypertension to glaucoma as well as progression of glaucoma. An IOP target range of at least 30 % lower than initial presentation is helpful in setting treatment goals but requires individual adjustment. In contrast to other tests, IOP can be determined objectively. It is best determined with Goldmann applanation tonometry, the gold standard of measuring intraocular pressure, which is widespread and allows comparison with historical data. Tono-Pen, dynamic contour, and even the latest generation noncontact tonometry also produce accurate and repeatable results that rival or exceed Goldmann applanation. Where accurate IOP is not crucial or a tonometer not available, the experienced examiner can use scleral palpation to estimate IOP.Within the population, IOP has a non-Gaussian distribution with an average of about 16 mmHg (worldwide range 11–18 mmHg). Examiners should be aware that IOP has 2–6 mmHg diurnal variation, with the maximum in the morning. The water-drinking test has regained interest because it can be used to estimate peak pressures and risk of glaucoma.IOP can be influenced by numerous medications that increase outflow resistance (steroids) or cause angle closure from anticholinergic action or forward rotation of the ciliary body. IOP increase from steroids may not be reversible. Patients with at least moderate glaucoma should be made aware that high-resistance wind instruments as well as extreme body postures can contribute to progression and should be avoided.

Original languageEnglish (US)
Title of host publicationClinical Glaucoma Care
Subtitle of host publicationThe Essentials
PublisherSpringer New York
Number of pages22
ISBN (Electronic)9781461441724
ISBN (Print)9781461441717
StatePublished - Jan 1 2014

ASJC Scopus subject areas

  • General Medicine


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