Hyperbaric
oxygen transiently improves visual fields in open-angle glaucoma in a
dose-dependent manner.
Clinical
Bottom Line:
1.
Hyperbaric oxygenation improves visual field but not intra-ocular pressure in
open-angle glaucoma.
2.
Improvement in fields is shown to ameliorate over six months following
treatment.
3.
Improvement was dose-dependent over the range 10-30 treatments.
Appraised
by:
Mike Bennett, Dept of Diving and Hyperbaric Medicine, Prince of Wales Hospital,
Sydney; Tuesday, 19 January, 1999
Clinical
Scenario:
A patient with open-angle glaucoma and restricted visual fields.
Three-part
Question:
In chronic open-angle glaucoma, does the application of hyperbaric oxygen
compared to normobaric air, result in any improvement in visual fields, visual
acuity or intra-ocular pressure?
Search
Terms:
Hyperbaric oxygenation, glaucoma
The
Study:
Double-blinded
randomised controlled trial with intention-to-treat.
Patients
with primary open-angle glaucoma taking regular medication to reduce
intra-ocular pressure.
Control
group (N = 20; 20 analysed): Usual care with sham treatment at 2ATA breathing
10.5% oxygen to simulate normal air breathing.
Experimental
group (N = 91; 91 analysed): Usual therapy plus oxygen at 2ATA for 90 minutes
daily for 10 (n=20), 15 (n=20), 20 (n=20) and 30 treatments (n=31)(5 days/week).
The
Evidence (using 30 treatment group example):
Non-Event
Outcomes
Time to outcome
Before HBO After HBO
P-value
Blind
spot (cm2)
6 weeks
0.76
0.52
<0.05
Blind
spot (cm2)
6 months
0.76
0.6
>0.05
Visual
field
Isopter4
(cm2)
6 weeks 123
135
<0.05
Visual
field
Isopter4
(cm2)
6 months
123
131.5
>0.05
Comments:
1.
There were no significant changes in visual acuity or intra-ocular pressure
across the groups.
2.
The two groups were not compared directly, rather they were each compared with
their own pre-treatment baseline.
3.
There were no statistically significant changes in the control group in terms of
fields, blind spot or pressure.
4.
The changes in visual field and blind spot areas before and after hyperbaric
oxygenation remain statistically significant at 3 months, but not six months.
5.
Reduction in blind spot area and improvement in visual field were dose
dependent, becoming non-significant at 10 treatments compared to control.
6.
The authors recommend 20 treatment course with re-treatment as required.
Expiry date: October 2003
References:
1.
Bojic L, Racic G, Gosovic S, Kovacevic H. The effect of hyperbaric oxygen
breathing on the visual field in glaucoma. Acta Ophthalmologica 1993;
71:315-319.
2.
Bojic L, Kovacevic H, Andric D, Romanovic D, Petri N. Hyperbaric oxygen dose of
choice in the treatment of glaucoma. Arh Hig Rada Toksikol 1993; 44:239-247.
3. Bojic L, Kovacevic H, Gosovic S, Denoble P. The effect of hyperbaric oxygen on glaucoma: a prospective study. In: Bakker DJ, Schmutz J, eds. Hyperbaric Medicine Proceedings, 2nd Swiss Symposium on Hyperbaric Medicine. Basel, Switzerland 1990:273-275.
