Retina pt. 3 - Macula Flashcards
1
Q
What are the parts/layers/components of the macula?
A
- Perifovea
- Parafovea
- Fovea - foveola, umbo
2
Q
What is the fovea?
A
- Shallow depression in the center of the macula that results from retinal neuron displacement
3
Q
What are the dimensions of the fovea?
Width
Thickness
Location
A
- 1.5 mm wide (1 DD)
- 0.25 mm thick
- 3.4 mm temporal from optic disc
4
Q
What amount of visual field corresponds to the fovea?
A
5 degrees
5
Q
What is the clivus?
A
Curved wall where the fovea starts to depress
6
Q
What are three reasons why the fovea is darker?
A
- Macular pigments - high concentration of lutein and zeaxanthin at the fovea
- Densest RPE cells
- Thickest choroidal capillary bed
7
Q
What are the types of macular pigments?
A
Xanthophylls - lutein and zeaxanthin
8
Q
What macular pigment is more concentrated at the fovea?
A
Zeaxanthin
9
Q
What macular pigment is more concentrated outside the fovea?
A
Lutein
10
Q
How do macular pigments accummulate?
A
Diet - newborns lack macular pigment
11
Q
What is the function of macular pigments?
A
- Absorb damaging short wavelengths of light
- Provide antioxidant protection to the retina
12
Q
Where are macular pigments located?
A
Throughout the retina - OPL, Muller cells, PR inner fibers, rod outer fibers
