3
Eyelids
Open the eyelids M. levator palpebrae sup. (N. oculomotorius)………ptosis
Close the eyelids M. orbicularis oculi (N. facialis)………lagophtalmus
voluntary closure
blinking reflex:
touching the eyelashes
strong light, approaching objects, loud sound
sleep (increased tone of M.orbicularis)
5
Eyelids
Open the eyelids M. levator palpebrae sup. (N. oculomotorius)………ptosis
Close the eyelids M. orbicularis oculi (N. facialis)………lagophtalmus
voluntary closure
blinking reflex:
touching the eyelashes
strong light, approaching objects, loud sound
sleep (increased tone of M.orbicularis)
7
• plasma ultrafiltrate, slightly hypertonic, 1 ml / day
• lubricates and protects
• rinsing out foreign objects
• lyzozym + secretory antibodies + antigenes
• emotional tool
• reflex: afferent: n. V. ------> brainstem (pons)
• efferents: n. VII----> ggl. pterygopalatinum -----> n.V. --> glands
Tears
10
• the visible spectrum: 400-700 nm • importance of the reflected spectrum
• light intensity: candela (cd) • luminance: from 10-6 cd/m2 to 107 cd/m2 • normal conditions 1-40 X differences • phosphenes (deformation, migrain, electric stimuli) • importance of the contrast
Light and vison
11
visible spectrum: 400-700 nm • importance of the reflected spectrum
• light intensity: candela (cd) • luminance: from 10-6 cd/m2 to 107 cd/m2 • normal conditions 1-40 X differences • phosphenes (deformation, migrain, electric stimuli) • importance of the contrast
Light and vison
12
visible spectrum: 400-700 nm • importance of the reflected spectrum
• light intensity: candela (cd) • luminance: from 10-6 cd/m2 to 107 cd/m2 • normal conditions 1-40 X differences • phosphenes (deformation, migrain, electric stimuli) • importance of the contrast
Light and vison
27
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Optical properties of the eye
29
total refractory power: ~ 60 D cornea: ~ 40-43 D lens: ~ 17-20 D vitreous humor: - 4 D
Refractory index
34
lens: flat, weak refractory power lens: thick, refractory power strong
looking far ~ parallel light rays ciliary muscles relaxed zonula fibres stretched, lens flat
looking close diverging light rays ciliary muscles contracted zonula fibres relaxed, lens thick
Accommodation
37
The spatial resolution power of the eye
α
α ≥ 1’ Light rays from two separate points must have 1’ (minute of arc) angle. 1 cm from 57 cm distance is 1° (degree of arc).
49
intraocular pressure: ~16 Hgmm, due to the aqueous humor measuring: tonometry •composition: plasma ultrafiltrate
•production: active, epithelial cells in the ciliary body
•drainage: passive, transcellular vesicular transport
role of the pupil
trabecular meshwork
Schlemm chanels
Intraocular pressure
49
53
• glaucoma
• headache (sudden onset, radiates into the orbit,
into the temporal region)
• blurred vision
• bradycardy
• painful, hard eyeballs
• nausea, vomitus
Intraocular pressure
56
Her laughter was historical indeed when he finally proposed to her.
Gaze tracking while reading
fixation fast, forward
fast, backwards „regression”
Eye movevements
Optical axis unchanged
(conjugated movements)
Optical axis changed
(vergence movements)
Movement
type
Fixation Rotation Saccades Pursuit
movements
Convergence Divergence
Duration max. 0.5 s
Speed up to
1000°/s
up to 60°/s
Angle 10°
compensa
tion
Distance Object close Object
far away
57
Eye movements conjugated eye movements
torsion movements
converging, diverging movements
saccades short and fast with or without head movements speed = up to 500-1000 °/s (!) fixation periods 0.5 s, 10000/day pursuit movements if object, head or body moves speed = up to 60 °/s
58