optician does light to receptor gp does receptor to pathway opthalmology does pathwy neurology does cortex psychiatrist does perceptions
eye is very small compared to the hold for the eye this is because fat and muscle fill that space, as well as nerve entry and extension ot meninges
binocular vision is granted by 2 eyes and it also increases field of vision
eye exam usually is performed out to in
out to
- sclera (covered by conjentivae)
- cornea (transparent and does 22/3rds of total refraction) then
- choroid (extension of brain pia / arachnoid)
- supplies receptors cells of retina with oxygen
- iris
- lens
- ciliary muscle
- controls lens shape
- ciliary body
- secretes aqeous humour
- Retina
- in to out
- ganglion neurons
- ganglion cell layer
- bipolar cell layer
- receptor layer
- pigmented epithelium
- fovea and macula
- fovae is the centre of vision and macula is its area
- there are no blood vessels in this area as we want good vision in
- in to out
retinopathies
- diabetes mellitus
- glaucoma
- papilloedema
Eye muscles
optic is physics
ocular is of the eye
6 extraocular muscles (cranial nerves III, IV, VI) conjugate gaze / convergence squint / stabismimus -diplopia
LR6(SO4)3 This means lateral rectues is 6th cranial nerve superior oblique is 4th everything else is 3rd
altering fixation - saccades (rapid jumps) smooth pursuit - fixate on movning target at rest - micro saccades (unable to percieve)
optics and the image
most focusing is done by the cornea lense can adjust with age it stiffens and you are less able to communicate - presbyopia
zonular fibres connect lens to ciliary muscle
lens is stretched to accomodate for closer and farther objects
characteristic pattern of visual field loss is called - scotoma
Visual fields nasal and temporal hemifields correspond to opposite names nasal and temporal hemiretina
visual pathways retina -geniculate- cortex pathways
lesions to different paths in the optic nerve/tract/chiasm leads to different visual deficiencies
cone cells - colour clarity rods - rest of room