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The definition of normal-tension glaucoma
B L Lee1, R Bathija, R N Weinreb
1Glaucoma Center, University of California at San Diego 92093-0946, USA.
Journal of Glaucoma
|January 1, 1999
Summary
Definitions for normal-tension glaucoma (NTG) have varied significantly over time. Recent studies show a trend towards stricter criteria, including lower intraocular pressure (IOP) and detailed optic disc and visual field assessments.
Area of Science:
- Ophthalmology
- Glaucoma Research
- Clinical Definitions
Background:
- Normal-tension glaucoma (NTG) is a form of glaucoma where optic nerve damage and visual field loss occur despite intraocular pressure (IOP) within the statistically normal range.
- The diagnostic criteria for NTG have evolved, necessitating an evaluation of their consistency over time.
Purpose of the Study:
- To assess the variability and consistency in the definition of normal-tension glaucoma (NTG) in published literature.
- To identify trends in diagnostic criteria for NTG over a 25-year period.
Main Methods:
- A comprehensive literature search was conducted for articles on NTG published between 1973 and 1997 in three major ophthalmology journals.
- Reviewed articles to identify and analyze the specific criteria used for defining NTG, focusing on intraocular pressure (IOP) thresholds and optic nerve/visual field assessments.
Main Results:
- Sixty-three articles defining NTG were identified, with 30 from 1973-1992 and 33 from 1993-1997.
- Maximum acceptable IOP for NTG ranged from 17 to 26 mmHg, with a trend towards <= 21 mmHg in studies from the last 5 years of the review period.
- Inclusion criteria for optic disc and visual field characteristics were present in 87% and 89% of articles, respectively, with specific features increasingly detailed in recent publications.
Conclusions:
- The definition of NTG has been inconsistent over the 25-year study period.
- Recent publications (1993-1997) demonstrate a move towards more standardized criteria, including a maximum IOP of <= 21 mmHg and detailed descriptions of glaucomatous optic disc and visual field changes.