Corneal responses to lens transmissibility.
BACKGROUND
Lens transmissibility (Dk/L) and corneal relief from hypoxia are not linearly related. We describe graphically and by equations the relationship between corneal relief (scaled in oxygen shortfall units) and Dk/L across the transmissibility range of 1.2 to 189 x 10(-9) (cm/sec)(ml O2/ml mmHg).


METHODS
Corneal responses to 28 Dk/L levels across the transmissibility range were expressed in oxygen shortfall units (osús), a relative scale of 100 steps bounded by each cornea's normal oxygen uptake rate with no contact lens in place (set = to 0 osús), and its maximum uptake rate for the open eye due to static PMMA lens wear (set = to 100), thus allowing the degree of hypoxic stress exhibited by all corneas to be compared on the same relative scale.


RESULTS
Responses of 11 human corneas to each of those 28 Dk/L steps were recorded across that entire transmissibility range, and their collective relationship described graphically.


CONCLUSIONS
The graphic composite of all corneal responses to transmissibility steps across the Dk/L range of 1.2 to 189 X 10(-9) (cm/sec)(ml O2/ml mmHg) was found to be monotonic and continuous. While no single equation was found that optimally described (predicted) corneal responses across that entire spectrum, equations of the quadratic form fit limited domains of Dk/L (r2 values exceeding 90%) adequately for most laboratory and clinical applications.
Smith
B J
BJ
Ohio State University, College of Optometry, Columbus, USA.
Fink
B A
BA
Hill
R M
RM
D000328:Adult; D003261:Contact Lenses / Q000009:adverse effects; D003315:Cornea / Q000502:physiology*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008768:Methylmethacrylates; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology*
D008768:Methylmethacrylates; D010100:Oxygen