Term
| What are RPE cells regenerating? |
|
Definition
| rhodopson, the rod photopigment |
|
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Term
|
Definition
|
|
Term
| In the light, what is seen in RPE more than in the dark? |
|
Definition
|
|
Term
| How is retinal moved between RPE and photoreceptors? |
|
Definition
|
|
Term
| Can the RPE influence accommodation and the pupil? |
|
Definition
|
|
Term
| What is the voltage across the eyeball when it is in the light? |
|
Definition
|
|
Term
| What is the polarity of the eyeball's voltage? |
|
Definition
| cornea is positive; retina is negative |
|
|
Term
| What controls the voltage across the eye? |
|
Definition
| Light levels via the RPE; i.e. the more light that reaches the RPE, the more electrical potential the RPE generates |
|
|
Term
|
Definition
| electro oculograph. It measures voltage across the eyeball. |
|
|
Term
| What is retinal growth factor? |
|
Definition
| compound released that triggers the eye to grow longer |
|
|
Term
| What can cause the release retinal growth factor? |
|
Definition
| blur. Blur induces electrical changes triggered by accommodation |
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|
Term
| What happens when the optic nerve is severed? |
|
Definition
| The eye can still change length, so the system that controls it is limited to the eyball itself. |
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|
Term
| If the retina detaches, what can be left behind in the RPE? |
|
Definition
| rod photoreceptors that break off at the ciliary process |
|
|
Term
| What is the turnover rate for PR disc renewal? |
|
Definition
|
|
Term
| How many rods contact each RPE cell? |
|
Definition
|
|
Term
| How many discs does the average RPE cell phagocytize in one day? |
|
Definition
|
|
Term
| When do rods primarily renew? |
|
Definition
| At sunrise, right after their scotopic work is no longer needed |
|
|
Term
| When do cones primarily renew? |
|
Definition
| At dark, right after their photopic work is no longer needed. |
|
|
Term
| Why do PR discs slough off? |
|
Definition
| oxidative damage builds up til they are no longer viable. |
|
|
Term
| What kind of light damages PR discs faster? |
|
Definition
| The higher the frequency/shorter the wavelength the more it damages (UV light = bad) |
|
|
Term
|
Definition
|
|
Term
|
Definition
| skin cancer and cataracts |
|
|
Term
|
Definition
| mostly absorbed by cornea and can cause photokeratitis, possibly AMD |
|
|
Term
| What does drusen signify for the RPE? |
|
Definition
| That the RPE has died in that location and lipofuscin has accumulated. |
|
|
Term
| What UV light is 32- 400 nm |
|
Definition
|
|
Term
| What UV light is 280-320 nm |
|
Definition
|
|
Term
| What UV light is 200-280 nm |
|
Definition
|
|
Term
|
Definition
|
|
Term
| What is retinitis pigmentosa? |
|
Definition
| Damage to the RPE from genetic predisposition. |
|
|
Term
| How many cones are embedded in each RPE cell? |
|
Definition
|
|
Term
| What does Vit A overdose cause? |
|
Definition
|
|
Term
| What is the range of intensity our eye can perceive? |
|
Definition
| 10 log units (sunlight down to starlight) |
|
|
Term
| What range of light does the pupil control? |
|
Definition
|
|
Term
| What is the remaining range of light adaptation is NOT attributed to the pupil? |
|
Definition
|
|
Term
| What is the dark adaptation curve? |
|
Definition
| light intensity vs human physiological response to it. |
|
|
Term
|
Definition
| the peak wavelength sensitivity change due to transitioning from photopic to scotopic and back. |
|
|
Term
| What is the peak wavelength sensitivity for scotopic vision? |
|
Definition
|
|
Term
| What is the peak wavelength sensitivity for photopic vision? |
|
Definition
|
|
Term
| What is the photochromic interval? |
|
Definition
| the difference in sensitivity between rods and cones |
|
|
Term
| How much more sensitive are rods than cones? |
|
Definition
|
|
Term
| What color of light is the exception to the photochromic interval? |
|
Definition
| long wavelengths such as red and orange |
|
|
Term
| How many rods are there per eye? |
|
Definition
|
|
Term
| How many cones are there per eye? |
|
Definition
|
|
Term
| Where is the retina most sensitive to light? |
|
Definition
| peripheral vision due to rod density |
|
|
Term
| At their peak density, which is packed closer, rods or cones? |
|
Definition
| Niether, they are of equal PEAK density, though rods might have an advantage in some individuals |
|
|
Term
| Where are rods arranged most densely? |
|
Definition
| 20* away from the fovea/off axis |
|
|
Term
| What is the quickest flash of light we can see? |
|
Definition
| 1/10 of a second for rods (100 ms) 1/100 of a second for cones (10ms) |
|
|
Term
| What is temporal summation? |
|
Definition
| The summation of multiple discrete stimuli over time |
|
|
Term
| What is an implication of temporal summation? |
|
Definition
| all photons detected within 100 ms of each other blur together and cannot be separated from each other. |
|
|
Term
|
Definition
| luminance x time = constant necessary for perception |
|
|
Term
| What is the smallest size light we can see? |
|
Definition
| 10 arc min for rods, 1 arc min for cones |
|
|
Term
|
Definition
| the larger the area, the higher the luminance needed for summation effects to be seen. |
|
|
Term
| Can we see a single photon? |
|
Definition
| yes, under photopic conditions |
|
|
Term
|
Definition
| change in luminance / total luminance = constant |
|
|
Term
| What is the Rod/Cone break? |
|
Definition
| When the rods and cones switch over from scotopic to photopic and vice versa |
|
|
Term
| How long do cones stay 'on' during dark adaptation? |
|
Definition
| About 12 minutes, then they hand things over to the rods |
|
|
Term
| How long does it take for rod PR's to be fully adapted to the dark? |
|
Definition
|
|
Term
| Why is there a sharp break in the dark adaption curve? |
|
Definition
| The cones are handing off to the rods in a 'relay race' style |
|
|
Term
| What is the half life for rod photo pigments? |
|
Definition
|
|
Term
| What is the half life for cone photo pigments? |
|
Definition
|
|
Term
| How many half lives does it take to regenerate 94% of bleached PR pigments? |
|
Definition
|
|
Term
| Due to their difference in half life times, how long doe sit take for rods and cones respectively, to reach 94% pigment regeneration? |
|
Definition
| 6 minutes for cones, 20 minutes for rods |
|
|
Term
| What are the 5 necessities for a Goldmann-Weekers Dark Adaptometer? |
|
Definition
Ganzfeld to light adapt subject to
adaptation lights for bright illumination
red fixation light
recording drum to mark retinal threshold
Test spot located 20 degrees away from the fixation light |
|
|
Term
| What does a low threshold with no break in the dark adaptation curve indicate? |
|
Definition
|
|
Term
| What does a high threshold for the dark adaptation curve indicate? |
|
Definition
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