Oxygen in the anterior chamber of the human eye.
Oxygen partial pressure (pO2) was measured in the anterior chamber of the human eye during routine cataract surgery using a polarographic oxygen electrode. We found a reproducible spatial distribution of oxygen in the aqueous humor. The pO2 (n = 8) was 44.9 +/- 9.1 mmHg in the chamber angle, 35.0 +/- 10.9 mmHg above the pupillary margin, and 13.5 +/- 8.0 mmHg in front of the center of the pupil. Pretreatment of the eye with the alpha-adrenergic agonist phenylephrine (5%) resulted in a marked reduction in pO2 to 19.8 +/- 5.8 mmHg in the chamber angle, 13.4 +/- 4.7 mmHg above the pupillary margin, and 7.4 +/- 3.3 mmHg in front of the center of the pupil (n = 8). The pO2 in the anterior lens was very low (2.5 +/- 0.6 mmHg, n = 7). We conclude that oxygen is supplied at the anterior iris surface to the aqueous humor. The lens is an extremely low oxygen compartment. Topical phenylephrine causes anterior-segment hypoxia, probably by the constriction of iris vessels.
Helbig
H
H
Universitäts-Augenklinik, Klinikum Steglitz, Freie Universität Berlin, Germany.
Hinz
J P
JP
Kellner
U
U
Foerster
M H
MH
D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000187:drug effects / Q000378:metabolism*; D002387:Cataract Extraction; D004566:Electrodes; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009883:Ophthalmic Solutions; D010100:Oxygen / Q000032:analysis / Q000502:physiology; D010101:Oxygen Consumption; D010656:Phenylephrine / Q000494:pharmacology; D011048:Polarography; D011897:Random Allocation
D009883:Ophthalmic Solutions; D010656:Phenylephrine; D010100:Oxygen