Illumination Adaptation Flashcards
What are Scotopic parallel pathways?
Low light systems with rod vision only and higher sensitivity to low colour vision.
Define Dark Adaptation.
Light adaptation wherein illumination changes from high to low, which bleaches photopigment.
Chromophore and Opsin must recombine to regain their sensitivity in order to respond to light.
Define Light Adaptation.
Illumination changes from low to high and the available photopigment in the retina is bleached in order to reduce sensitivity and adapt to light.
How long does it take for rods to adapt to light?
Rod pigment regenerates in 30mins or over in order to regain maximum sensitivity.
How long does it take for cones to adapt to light?
Cone pigment regenerates in 6mins to gain maximum sensitivity.
What are Mesopic parallel pathways?
Rods and cones act simultaneously with no mutual interaction or overlap with sensitivities.
What is Chromatic Adaptation?
When photopigment molecules adapt to an otherwise black and white image.
What are Photopic visual pathways?
Parallel pathways with a high light system and cone vision only. Has low absolute sensitivity and good colour vision.
What is Duplex nature when describing the retina?
When rods and cones function as independent parallel pathways under different light intensities.
What is the best area of sensitivity for the Scotopic visual pathway?
Periphery of the retina where most rods are concentrated.
Which visual pathway is the best for night time vision?
Scotopic visual pathway, because they are good for low illumination; cones aren’t sensitive enough for night vision.
What is the best area of sensitivity for the Photopic visual pathway?
The central retina where most cones are concentrated.
Which visual pathway is the best for daytime vision?
Photopic visual pathway which is good for high illumination; because rod photopigment gets bleached and becomes inoperable during daytime.
What are two examples of retinal diseases that affect cones and rods respectively?
Macular Degeneration negatively influences cones.
Retina Pigmentosa negatively influences rods.
What is the level of sensitivity for low light ambience?
High sensitivity
What is the level of sensitivity for high light ambience?
Low sensitivity
What does macular degeneration do to your vision?
Creates a central scotoma or blindspot which is common in elderly.
What does retinal pigmentosa do to your vision?
Causes night or complete blindness
Which visual alterations help regulate and adjust sensitivity to different illumination and photopigments?
Sunglasses and dilated or constricted pupils which match available photopigments.
How do individuals with macular degeneration adapt to their condition?
They avoid the blindspot in order to see clearly.
How is macular retinal pigmentosa treated?
Magnification of the central field which makes for a better visual experience.
