Vision Physiology I Flashcards
Light speed _____ when it passes through a transparent substance
Light speed decreases when it passes through a transparent substance
REFRACTIVE INDEX (RI) is the ratio of the speed of light in _____ to the speed of light in the _____
REFRACTIVE INDEX (RI) is the ratio of the speed of light in air to the speed of light in the substance
An angulated interface with different refractive indices causes _____ of light
An angulated interface with different refractive indices causes bending of light
The ____ of _______ increases as the difference in RI increases and the degree of angulation increases
The degree of refraction increases as the difference in RI increases and the degree of angulation increases
The light rays are eventually focused on the _____.
The light rays are eventually focused on the retina
______ lens causes converging of light rays
convex lens causes converging of light rays
In a convex lens, lightrays begin to bend in the _____ and
converge at the ____ _____.
In a convex lens, lightrays begin to bend in the periphery and
converge at the focal point.
A _____ lens causes diverging of light rays.
A concave lens causes diverging of light rays.
Refractive power is measured in ______
diopters
The ______ the diopter, the ______ the lens is able to bend light rays to a simple____ ____.
The greater the diopter, the greater the ens is able to bend light rays to a simple focal point.
Which lenses are more likely to be measured in diopters?
Convex lenses
What structure of the eye has the greatest refractive power?
the cornea
What tells you more about refractive power, the intrinsic refractive power value or the difference between refractive power values?
the difference between refractive power values
What is the refractive power of the lens?
20 diopters
_______ is the ability of the lens to change shape and become fatter or flatter.
accomodation
Why is accomodation necessary?
to focus the image on the retina
On the retina, the image is ____ and ____.
inverted and reversed
Relaxed lens is almost _____ in shape
Relaxed lens is almost spherical in shape
Lens held in place by _____ _____ that cause the lens to be _____ under normal resting conditions
Lens held in place by suspensory ligaments that cause the lens to be flat under normal resting conditions
_____ pulls ligament forward relaxing tension on suspensory ligament making the lens _____
Contraction pulls ligament forward relaxing tension on suspensory ligament making the lens fatter
refractive power is greater when ciliary muscles are _____and lens is ____
refractive power is greater when ciliary muscles are contracted and lens is fatter
Ciliary muscle controlled by _____ nerve signals
Ciliary muscle controlled by parasympathetic nerve signals
When a person looks at an object in the distance, do the ciliary muscles need to contract?
no
For near vision, the ciliary muscles ____and the central lens thickness ____to increase its power.
For near vision, the ciliary muscles contract and the central lens thickness increases to increase its power.
Presbyopia:
Inability to _____
_____ of the proteins of the lens
Lens less ____
Presbyopia:
Inability to accommodate
Denaturation of the proteins of the lens
Lens less elastic
hyperopia
accommodate to see ____ objects.
eyeball too ____ or refractive power of lens is too ____
the focal point goes ____ _____ _____
hyperopia
accommodate to see far objects.
eyeball too short or refractive power of lens is too small.
the focal point goes beyond the retina
myopia
when eyeball is too _____ or too ____refractive power in the lens.
Focal point is ____ ____ ____.
myopia
when eyeball is too long or too much refractive power in the lens.
Focal point is before the retina.
Myopia corrected with _____ lens
Myopia corrected with concave lens
Hyperopia corrected with _____ lens
Hyperopia corrected with convex lens
Astigmatism causes a change in the ____ of light.
angulation
Cataracts are characterized by a cloudy or _____area of the ____caused by the ____ of lens proteins
Cataracts are characterized by a cloudy or opaque area of the lens caused by the coagulation of lens proteins
Visual Acuity
____ or _____ of vision
Ability to perceive ____ _____
Discern letters or numbers at a given distance (____ feet)
Visual Acuity
Clarity or sharpness of vision
Ability to perceive small details
Discern letters or numbers at a given distance (20 feet)
Motion parallax: a ____ depth cue in which we view objects that are closer to us as moving ____ than objects that are further away from us.
Motion parallax: a monocular depth cue in which we view objects that are closer to us as moving faster than objects that are further away from us.
stereopsis: you can see with ____ eyes better than you can see with____
stereopsis: you can see two eyes better than you can see with one
Intraocular fluid keeps the eyeball ____ and _____.
Intraocular fluid keeps the eyeball round and distended
2 types of intraocular fluid:
- ______ humor: freely flowing fluid
- _____ humor: Gelatinous mass with little flow of fluid
2 types of intraocular fluid:
- Aqueous humor: freely flowing fluid
- Vitreous humor: Gelatinous mass with little flow of fluid
Formation of aqueous humor:
- Produced by ___ ______ of the ____ ____ at a rate of 2-3 microliters/min
- Aqueous humor formed by ____ _____ of ____ _____
- Active transport of ___ followed by ____ and ____
- Water follows by ________
Formation of aqueous humor:
- Produced by ciliary processes of the ciliary body at a rate of 2-3 microliters/min
- Aqueous humor formed by active secretion of ciliary processes
- Active transport of Na+ followed by Cl- and HCO3-
- Water follows by osmosis
Outflow of aqueous humor from the eye:
Flow of aqueous humor through the ___ into the _____ ____ of the eye
Fluid flows _____ to the ____ and into the angle between the ____ and ____
____ __ _____ and into the _____ __ ____which empties into ______ _____.
Outflow of aqueous humor from the eye:
Flow of aqueous humor through the pupil into the anterior chamber of the eye
Fluid flows anterior to the lens and into the angle between the cornea and iris
Meshwork of trabeculae and into the canal of schlemm which empties into extraocular veins
Intraocular pressure measures how quickly the flow of ____ ____ enters ____ __ ____.
Intraocular pressure measures how quickly the flow of aqueous humor enters canal of schlemm
Intraocular pressure is normally __mmHg with a range of 12-20 mmHg
Intraocular pressure is normally 15 mmHg with a range of 12-20 mmHg
