Effects of photocoagulation on intraretinal PO2 in cat.
OBJECTIVE
To test the hypothesis that intraretinal Po(2) increases after photocoagulation.


METHODS
Anesthetized cats underwent retinal argon laser photocoagulation. At least 4 weeks after treatment, Po(2)-sensitive microelectrodes were used to record intraretinal Po(2) profiles from healed photocoagulation lesions in anesthetized cats breathing air. Histopathologic examination of the retinas was used to confirm that the photoreceptors were destroyed and that the inner retinal layers were preserved, though somewhat disorganized, as in human panretinal photocoagulation (PRP).


RESULTS
The retina and tapetum were thinner in the lesioned retina than in the nonphotocoagulated retina. Average Po(2) across the inner 50% of the retina was higher (22 +/- 10 mm Hg) in photocoagulated retina than in untreated retina (14 +/- 7 mm Hg; P < 0.01; n = 13 cats). The minimum Po(2) was also significantly higher, whereas choroidal Po(2) was significantly lower in the photocoagulated retina than in untreated retina. No significant difference was found in the preretinal vitreous. After lesions, inner retinal Po(2) could also be maintained above zero, even in the absence of retinal circulation.


CONCLUSIONS
Previous measurements showed increased Po(2) in the preretinal vitreous of rabbits and pigs (but not cats) after photocoagulation of the outer retina. These intraretinal measurements in cats provide further evidence for a chronic increase in inner retinal Po(2) in lesioned areas during air breathing.
Budzynski
Ewa
E
Departments of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA.
Smith
Jennifer H
JH
Bryar
Paul
P
Birol
Gulnur
G
Linsenmeier
Robert A
RA
D000818:Animals; D002415:Cats; D002829:Choroid / Q000378:metabolism; D005260:Female; D017736:Ion-Selective Electrodes; D017075:Laser Coagulation; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D010313:Partial Pressure; D012160:Retina / Q000378:metabolism* / Q000473:pathology / Q000601:surgery*; D014945:Wound Healing / Q000502:physiology
D010100:Oxygen