VISUAL SENSITIVITY AT TRANSIENT ADAPTATION : Dynamic Evaluation Method of Visibility Utilizing Effective Luminance (Part 1)

Dynamics of adaptation at high luminances: adaptation is faster after luminance decrements than after luminance increments.

As is well known, dark adaptation in the human visual system is much slower than is recovery from darkness. We show that at high photopic luminances the situation is exactly opposite. First, we study detection thresholds for a small light flash, at various delays from decrement and increment steps in background luminance. Light adaptation is nearly complete within 100 ms after luminance decreme...

Luminance adaptation increased the contrast sensitivity of retinal ganglion cells.

In the present study, the activity changes of chicken retinal ganglion cells in response to light stimuli with defined contrast were investigated, in the presence of various levels of sustained background illumination. Following a step increase of light illumination, the firing rate of most retinal ganglion cells increased abruptly, and then decreased to a steady-state level with a much lower f...

Recurrent varicose veins. Part 1: Evaluation utilizing duplex venous imaging.

There is the need to develop a universally accepted standard investigation for recurrent varicose veins. Duplex venous imaging offers a precise, non-invasive technique to make anatomic and hemodynamic diagnoses. A routine protocol of duplex imaging of recurrent varicose veins is described based on the known recurrent sources of reflux from deep to superficial veins. Results from this protocol i...

Luminance effects on visual acuity and small letter contrast sensitivity.

The purpose of this study was to evaluate the effects of luminance on visual acuity (VA) and small letter contrast sensitivity (SLCS). Computer-generated letter charts were used to measure VA and SLCS [6/7.5 (20/25) Snellen equivalent] as a function of stimulus luminance. Letter size (VA) and contrast (SLCS) were varied in equal logarithmic steps, making the task and scoring procedure comparabl...

Dynamic Visibility and the Level Set Method