Aqueous oxygen tension in glaucomatous and nonglaucomatous eyes.
OBJECTIVE
To compare aqueous oxygen tension in eyes with primary open-angle glaucoma (POAG), pseudoexfoliation glaucoma (PXG), and neovascular glaucoma (NVG), with normal eyes with senile cataracts.


METHODS
This study included 82 eyes of 82 patients with POAG (22 eyes), PXG (20 eyes), NVG (18 eyes), and cataracts (22 eyes). Before initiating surgery and while breathing room air, 0.2 mL of aqueous humor and 1 mL of arterial blood were aspirated in heparinized syringes under sterile conditions. Partial pressures of oxygen (PO2), carbon dioxide (PCO2), and pH of the samples were measured using a blood-gas analyzer.


RESULTS
Overall, aqueous PO2 was comparable among the study groups (P=0.202). After repeating the analysis in eyes with controlled and high intraocular pressure (IOP), a significant difference was observed in POAG eyes with high IOP (post-hoc test, P=0.046). Overall, a significant negative correlation (r=-0.184, P=0.045) was observed between IOP and aqueous PO2. The strongest correlation was observed in the POAG group (r=-0.507, P=0.016). Aqueous PO2 was higher than arterial PO2 in all study groups except POAG eyes, significantly so in the cataract and PXG groups (P=0.013 and P<0.001, respectively), implying a contribution of atmospheric oxygen to aqueous PO2. This contribution was lower in POAG eyes but the difference failed to reach statistical significance (P=0.262).


CONCLUSIONS
Aqueous oxygen tension was lower in POAG eyes with high IOP. A significant negative correlation was observed between IOP and aqueous PO2. Aqueous PO2 was higher than arterial PO2 suggesting a contribution by atmospheric oxygen.
Departments of *Ophthalmology ‡Pulmonology, Ahvaz Jundishapur University of Medical Sciences, Ahvaz †Ophthalmic Research Center, Labbafinejad Medical Center, Shahid Beheshti University of Medical, Sciences, Tehran, Iran.
Farideh
F
Sharifipour
Shahin
S
Yazdani
Mohammad
M
Pakravan
Esmaeil
E
Idani
D000368:Aged; D001082:Aqueous Humor / Q000378:metabolism*; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000378:metabolism; D017889:Exfoliation Syndrome / Q000378:metabolism*; D015355:Glaucoma, Neovascular / Q000378:metabolism*; D005902:Glaucoma, Open-Angle / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007429:Intraocular Pressure; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism*; D010313:Partial Pressure; D014065:Tonometry, Ocular
D002245:Carbon Dioxide; D010100:Oxygen