8.4 bonus Flashcards
What is the amount of tear per day?
~1g/day without extra stimulus (irritation, emotions) no production during sleeping
What is the role of tear film?
- Isotonic
- Clearing
- Immune function
- Supplying cornea
What is the feature of mucin layer?
- amphiphilic
-> Conjunctival goblet cells
What is the feature of lipid layer?
Hydrophobic, inhibits evaporation
- Contain Meibomian glands (or tarsal glands)
II. Regulation of tear production
1. What are 3 types of tears?
- Basal tears
- Psychic tears
- Reflex tears
II. Regulation of tear production
2. Characteristics of basal tears?
They are made to keep the cornea lubricated
II. Regulation of tear production
3. Characteristics of psychic tears?
They are caused by extreme emotions (happiness, sadness)
II. Regulation of tear production
4. Characteristics of reflex tears?
They come out in response to irritants, onion, pepper spray, …
III. Components of the human Aqueous Humor
1. How should the normal [Ascorbate] be in aqueous humor and plasma?
- Aqueous humor: 1.1 mM
- Plasma: 0.04 - 0.06
IV. Diseases
1. What are the features of cataract?
- the lens of the eye becomes cloudy
- Abnormal [ascorbate] in aqueous humor or plasma
- An example of normal vision on the left versus vision with cataracts on the right
IV. Diseases
2. What are the features of glaucoma?
- production/reabsorption disorders
- loss of peripheral vision
IV. Diseases
3. What are the features of macular degeneration?
oxidative stress, mitochondrial dysfunction, and inflammation
V. Accommodation
1. What is accommodation triad?
- (lens) accomodation (ciliary muscle contraction)
- convergence (converging axes of the eyeballs)
- miosis (pupil constriction, pupillary diameter decreases)
V. Accommodation
2. What are the characteristics of ciliary muscle? (innervation? Drug(s)?)
- innervation by the oculomotor (III) nerve
- parasympathetic innervation – ACh, mAChR (M3)
- atropin – decreases accomodation
V. Accommodation
3. describe the reflex?
Reflex (evoked by blurred, out-of-focus image) or voluntary:
- Afferent limb: retina – visual pathway – visual cortex
- Efferent limb:
Pretectal nucleus – Edinger-Westphal nucleus – ciliary ganglion
parasymp. – ciliary muscle
– constrictor muscle of the pupil
- oculomotor nucleus – external eye muscles (e.g. medial rectus muscle)
VI. Pupil size
1. What is the range of pupil size?
- Range: 1-8 mm (~30-fold change of the amount of light)
- Optimal: 3-5mm
VI. Pupil size
2. What is the innervation of
Sphincter muscle of the pupil? What is the inhibitor for this muscle?
- Occulomotor nerve (n. III.)
- parasympathetic, mAChR
- inhibitor: atropine
VI. Pupil size
3. What is the innervation of
Sphincter muscle of the pupil?
Sympathetic, α1R
VII. Disorders of refraction
1. What are the features of Presbyopia / ”old eye”
- The lens will be more and more rigid.
- Near point:
- 25 years – 10 cm (10 D)
- 45 years – 33 cm (3 D)
- 70 years – 100 cm (1 D)
VII. Disorders of refraction
2. What are the features of hyperopia?
- Hyperopia, hypermetropia (farsightedness)
- Eyeball is too short or refractive power is too weak.
VII. Disorders of refraction
3. What are the features of Myopia?
- Myopia (nearsightedness)
- Eyeball is too long or too much refractive power
VIII. Astigmatism
1. What is Astigmatism?
unequal focal power in different directions
VIII. Astigmatism
2. When does Astigmatism occur?
- Astigmatism mainly occurs when the cornea (front surface of the eye) is not spherical (round) in shape.
- Less frequently, astigmatism may be due to irregularities in the shapes of other components of the eye, such as the lens or the retina.
VIII. Astigmatism
3. What is Astigmatism test?
- Try to look at this “star” with one eye at a time and evaluate how you see the “rays”: do they all appear clean and crisp?
- If you find differences in one or more directions you may have astigmatism!
VIII. Astigmatism
3. What is Astigmatism test?
- Try to look at this “star” with one eye at a time and evaluate how you see the “rays”: do they all appear clean and crisp?
- If you find differences in one or more directions you may have astigmatism!
IX. Visual acuity
1. Explain visual acuity at the periphery
Between 20 and 30° acuity is reduced by a factor of ten. (10 arc min resolution)
X. Visual field
1, What are the types of visible perception possible?
X. Visual field
2. What are the causes of Visual field defects (scotoma)?
Causes:
* Multiple sclerosis (demyelinating disease)
* Methyl alcohol
* Quinine
* Macular degeneration
* Migraine (scintillating scotoma) *…
Make a schematic diagram of Photobleaching process
Make a schematic diagram of Photobleaching process
Describe Em-changes in inner segment
- Potential changes in the outer segment affect electronically the charge of the presynaptic membrane in the inner segment.
- In the dark, permanent depolarization causes Ca2+ - uptake in the inner segment through L-type Ca2+-channels.
- In the dark, glutamate is released from the photoreceptors. Photons decrease the intensity of glutamate release.
