Interventions for normal tension glaucoma
Abstract
Background
Normal tension glaucoma is a clinical condition in which the optic nerve is pathologically excavated and the visual field is disturbed. Nevertheless it has been assumed that intraocular pressure plays a role in the progression of visual field defects in this disease, but other, mainly vascular factors, have been discussed as well.
Objectives
The objective of this review is to assess the effects of medical and surgical treatments for normal tension glaucoma.
Search methods
Trials were identified from the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Group trials register), MEDLINE, EMBASE and BIOSIS Previews. Bibliographies of identified trials were searched to find additional trials. In addition, investigators and pharmaceutical companies were contacted. Date of last search: January 2001.
Selection criteria
This review includes randomised controlled trials in which medical or surgical interventions were compared to no treatment, placebo or other treatment in people with normal tension glaucoma.
Data collection and analysis
Data were extracted by two reviewers and results were compared for differences. Discrepancies were resolved by discussion. The heterogeneity of interventions, follow‐up periods and outcomes did not allow for statistical combinations of the study results.
Main results
According to the selection criteria on visual field loss, eight studies were included in this review. Only three studies focussed on patient relevant outcomes. In one trial a beneficial effect of lowering intraocular pressure was found, but only if data were corrected for cataract development. In two small studies a beneficial effect on visual field loss of brovincamine, a calcium antagonist was reported.
Authors' conclusions
In one study the effect of intraocular pressure lowering on visual field outcome was only significant when data were corrected for cataract development. The results for calcium antagonists are promising, but larger trials have to be performed. Studies that focussed on reduction of intraocular pressure or haemodynamic variables are not necessarily relevant for the outcome in people with normal tension glaucoma.
Plain language summary
Interventions for normal tension glaucoma
Normal tension glaucoma is most common among elderly people. Ongoing damage to the optic nerve (the major nerve sending signals to and from the eye) and the optic disc (where the optic nerve meets the eye) causes eyesight to worsen. Treatments to try to prevent vision deteriorating include eye surgery and several drugs. However, the review found little evidence on the effects of surgery or drugs to preserve vision. One drug, brovincamine, might be beneficial but more research is needed overall.
