Scotopic spectral sensitivity of phakic and aphakic observers extending into the near ultraviolet

Despite interest in ultraviolet (UV) damage and UV vision in lower vertebrates, there are few recent publications on human UV sensitivity. We obtained dark-adapted spectra from 4 aphakic and 5 normal eyes at 8.8 degrees off-fovea using the staircase method. Our measurements extended from 314.5 nm, near the limit imposed by corneal UV absorbance, to 650 nm. Phakic and aphakic sensitivities resembled the traditional rod spectrum at long wavelengths with a peak around 500 nm. However, aphakic subjects were much more sensitive than phakic observers below 420 nm. From phakic volunteers ranging in age from 22 to 43 we deduced lens absorbance which depressed sensitivity at 350 nm by approx. 4 log units (n = 7 phakic runs on 5 eyes, average age = 30) as expected. We show a maximum lens absorbance at 355-360 nm and a UV window in the lens absorbance at 315 nm consistent with data on optical density of human lenses.