H. Funatsu et al., A COMPARATIVE-STUDY OF THE EFFECTS OF ARGON AND DIODE-LASER PHOTOCOAGULATION ON RETINAL OXYGENATION, Graefe's archive for clinical and experimental ophthalmology, 235(3), 1997, pp. 168-175
Background: The purpose of this study was to compare the effects of di
ode and argon laser photocoagulation (DLP and ALP) on the preretinal o
xygen tension (P-O2): (1) directly over photocoagulated retina and (2)
in between laser lesions. Methods: DLP or ALP was applied to avascula
r rabbit retina to produce grade II lesions. On the day of the oxygen
measurement, a droplet of perfluorotributylamine was placed into the p
reretinal vitreous space over the lasered area of retina and the stead
y-state P-O2 was measured in normoxic animals using F-19 magnetic reso
nance spectroscopy. To determine the P-O2 directly over laser lesions,
small (5-mu l) droplets were placed over large (approximate to 4 mmx5
mm), confluent areas of treatment (burn area approximate to 95% of th
e treated retinal surface area). To determine the P-O2 in between lase
r lesions, a larger (10-mu l) droplet was placed over a field of scatt
er photocoagulation (burn area approximate to 30% of the treated retin
al surface area). The theoretical basis for this approach is discussed
. Results: Untreated eyes had a preretinal PO2 of 22 +/- 9 mm Hg (mean
+/- SD, n=15 eyes), The preretinal P-O2 was significantly higher over
confluent, 12-day-old ALP or DLP lesions (51 +/- 13 mm Hg, n=8 eyes;
P<0.01) compared to untreated eyes. However, at that time, DLP lesions
had significantly higher P-O2 values (60 +/- 13 mm Hg, n=4 eyes) than
did ALP lesions (42 +/- 6 mm Hg, n=4 eyes; P=0.04). The preretinal sp
ace in between laser lesions generally showed no significant increase
in P-O2 (P>0.05) over controls on post-treatment days 1, 5, 14 and 47.
The only exception was in the DLP group of eyes, in which a significa
nt increase in P-O2 over untreated or ALP-treated eyes occurred on pos
t-treatment day 5 (41 +/- 7 mm Hg, n=5 eyes; P=0.01). Over photocoagul
ation lesions in this study, DLP produced a greater increase in preret
inal P-O2 compared to control values than did ALP. Conclusions: These
results support the use of DLP as an alternative to ALP for the treatm
ent of retinal vascular diseases in which hypoxia is suspected to play
a role.