Optics Theoryflashcards.txt

• Accomodative convergence in prism diopters used by he patient per D of accommodation
• Relationship remains relatively constant
• Changes slightly inside 20cm

• Convergence response is less than convergence stimulus
• Gets more exo closer in

• Convergence response is greater than convergence stimulus
• Gets more eso closer in

• Retinoscopy
• Final neutrality in phoropter with working distance included

• Retinoscopy
• Neutral lenses that make patient emmetropic

The visualization of an object on a background different from the object itself

• Ability to just recognize a lateral misalignment on a frontal plane
• Most accurate type of acuity

Determination of a threshold of recognition of two or more targets or objects on a contrasting background

• Minimum contrast which is required to distinguish that there is a bar pattern rather than a uniform grey
• Measured by test gratings of equal width, bright and dark bars in a sine-wave pattern
• 30 cycles = 20/20

Amount of detail human eye is able to resolve

Diminished VA w/out structural abnormality of eyes or visual pathway, and uncorrectable by optical means

8.73 mm

B

L

Smaller pupils

1 mm diameter

Acuity can be increased by refractive means

Organic or pathological inhibition

Visual acuity without correction

Visual acuity with correction

• 20/50 = 1.00 D
• 20/100 = 1.50 D
• 20/200 = 2.50 D

Different refractive powers in the eyes of one patient

Fusion

Tropic patient

Exophoric patient

Adding prism to eyes

Exo diagnosis

• Brings image in for all
• Manages esophoria and esotropia

Temporal vision loss

1/4 of the visual field gone in one eye

1/2 of visual field gone in one eye

Both eyes involved, same side

Isolated area of visual field loss

• Intraocular pressure causing a degeneration of the ptic nerve
• Nerves must be degrading in order to be diagnosed

• Checks for macular defects
• Chin is 10 degrees
• Ears are 5 degrees

• Evaluates cranial nerves 3, 4, & 6
• Evaluates fixation
• Evaluates bony orbit

Both members of a yoke pair receive equal innervation

• Tested binocularly
• Tests under or overactions
• Use physiological H
• Checks 6 vardinal positions of the eye
• Ask about pain or double vision
• Test monocularly if abnormal

• Test binocularly
• Monocularly if restricted

• Test binocularly
• Monocularly if abnormal

Eyes are positioned down and out

• Affected eye is turned in due to relaxation of lateral rectus
• Susceptible to: diabetes, toxins, alcohol

Recorded as 4+

Recorded as 1+

A misplaced pupil

Unequal pupil size

• Small, constricted pupil
• Also a drug classification Of a substance that constricts the pupil

Drug classification that dilates pupil

The constriction of the pupil to light, as observed in the illuminated eye

The constriction of the pupil to light, as observed in the fellow eye

• Iris muscle responsible for constriction
• Parasympathetic innervation

• Iris muscle responsible for dilation of pupil
• Sympathetic innervation

The constriction of the pupil in response to acommodation or a near stimulus

• Paradoxical dilation to a bright light stimulus
• Sign of optic nerve disease
• Also called afferent pupillary defect (APD)
• Poorer direct response than consensual

• Optic tract
• Pretectal nucleus
• Edinger-Westphal Nucleus
• Cranial nerve 3
• Ciliary ganglion
• Inferior branch of Cranial nerve 3
• Sphincter

Manifested in eye with no light perception

• Small, irregular pupils, which do not react to light, but do have positive accommodation response
• Caused by syphilis, diabetes, alcoholism, and mid-brain tumors

• Benign
• Dilated pupil
• No immediate response to bright light; some after prolongued exposure
• Unilateral
• Common in females 30-50s

• Ptosis, miosis, anhydrosis
• Affected pupil will not redilate quickly after bright light exposure

Loss of accommodation due to age

The maximum ability to accommodate of a person

Half of amplitude o accommodation

Pushes light back; more makes you blurry

Worse

The far point of clear vision with accommodation relaxed

The nearest point of clear vision

Resting state of accommodation

Stimulation of accommodation caused by the nearness of a target

Automatic response to blur

• Range in accommodation due to chromatic aberration
• Varies on power depending on color

Constant parasympathetic stimulation of accommodation when there is no need to accommodation

Ciliary muscle is in a state of spasm

Prolonged, uniform spam of accommodation

• Drug that paralyzes accommodation and causes pupil dilation
• Bottled with RED caps

Condition where refractive conditions are not the same for the two eyes

Specific anisometropia where one eye is myopic and the other eye is hyperopic

• Each eye focussing on object
• Double vision

• Two eye focussing on object
• One image

• Highest level of binocular vision
• Having depth perception

• Objectively measures curves of the cornea
• Indicates cylinder power and axis
• Tests corneal integrity
• Used exclusively in contact lens patients

• Outer oil layer
• Aqueous middle layer
• Mucin inner layer

• 5 cell layers thick
• Very fast regenerating capabilities

• Basement membrane that epithelium adheres to
• Scarring occurs if penetrated

• Bulk of cornea mass
• Maintains cornea shape

Membrane the endothelium adheres to

• Corneal pump gets rid of edema
• No recovery if damaged

• Contactometer is placed in the head rest
• Readin taken of curve (standard steel ball)
• Power wheel adjusted by loosening the set screw and moving dial

• Too steep cornea: place +1.50 lens of central aperture
• Too flat: place -1.00 lens in front
• Consult conversion table

Flattest meridian of the cornea

Hyperopia

Myopia

• Most converging power in vertical meridian
• Use minus cylinder axis 180 to correct

• Heteronymous
• OD image is left
• OS image is right

• Homonymous
• OD image is right
• OS image is left

• Biocular
• Diplopia

• Binocular
• No depth perception

Depth perception, or stereopsis

• Relative size
• Light and shade
• Overlap

• Disparity between two images
• Eyes stimulated at corresponding points of fovea

• Disparity of visual field evaluated without monocular cues
• More sensitive
• Have to be binocular w/ bifoveal vision
• Tested w/ shapes of the Randot test

• Presence of smaller, more localized object
• Aided by monocular cues
• Less sensitive
• Tested by Wirt circles

• Measured in "seconds of arc"
• Best measurement is 20'

• Binocularity (do they have it)
• Refractive error (especially large anisometropia)
• Strabismus
• Age

Responsible for color vision

Long wavelength sensitive protein

Medium wavelength sensitive protein

Short wavelength sensitive protein

• Usually red-green
• 8% of males
• 0.5% of females

• Lighting
• Monocular testing

• Usually result of disease
• Blue-yellow defect
• Can be monocular

Do not see red

Do not see green

Do not see blue

• Tests macular function and central vision quality
• Portable
• @ 30cm
• Tests central degrees of vision
• Near correction
• Full illumination
• Monocular
• Focus on older patients
• Neovascularization
• High risk medications
• Unexplained vision loss

• Loss of vision due to malfunction of photoreceptors
• Black areas reported

• Decreased sensitivity to light
• Dim vision
• Reports blur or graying vision
• Hard to see areas

• Disturbance to light caused by physical change in retina
• Distortion of vision

accessory structures and organs of the eye; e.g., eye brows, skin around orbit

bony orifice in which the eye ball sits

lids, lashes, lacrimal system

staph infection of lid glands, with pus, pain, and redness

sterile clogging of lid glands, with no pus, pain, or redness

drooping of eye lid

eye lids do not completely close

in-turning of lids

out-turning of lids

drooping of skin of the eyelids

• lipid deposit in the skin of the eyelid
• do blood tests

normal lashes are in proper placement without any deposits or foreign substances at the base of the lashes or throughout lashes

inflammation of eyelid margins and lashes

loss of eyelashes

in-turning of lashes

inflammation of the Meibomian glands at the base of the lash

infection of the lacrimal sac with swelling and redness near the nose

inflammation of the lacrimal gland, with swelling and pain in the area of the lacrimal gland

conjunctiva that lines the lids

conjunctiva that overlies the sclera

• the amount of redness or vascularization
• recorded as 1+-4+

white to yellow, translucent avascular elevation of the conjunctiva

vascularized clear conjunctiva elevation, often giving a velvety appearance to the affected area

• a hyperplasia of the conjunctival tissue, usually in respones to environmental irritation
• prevention is key

• a degeneration of the bulbar conjunctiva involving the cornea
• prevention is key

a hemorrhage that causes great alarm in patients by the overall appearance of the conjunctiva

• swelling of the conjunctiva
• often an allergic response

normal sclera is white with few blood vessels seen

• an inflammation of the outer layer of the sclera with pain in the red area
• arthritic patients are predisposed

when a foreign object has penetrated the first five layers of the cornea, into the stroma

a cholesterol deposit in the periphery of the cornea

inflammation of the cornea

• tear break up time should be about 10 seconds
• measured by using fluorescein dye instilled into the lowe cul-de-sac

• where the aqueous drains
• size is graded from wide open (4+) to closed (0+)

white blood cells in the aqueous

smoky appearing precipitate of protein leaked from inflamed blood vessels

normal iris should have uniform color (sort of)

misplaced pupil

absence of iris

inflammation of iris

• an opacity of the crystalline lens
• about 400 different kinds

no crystalline lens

artificial lens implant

• remnants of hyaloid artery
• always there, but stiff vitreous keeps them out of the way; as vitreous ages, they can move around more

toward the nose (medial) portion of the back of the eye

• most diagnostic tool for glaucoma
• recorded as percentage of disc the cup occupies
• should be same between the two eyes
• should not ever change in lifetime
• recognize big, medium, and small

• pathological elevation of the disc margins
• could mean brain tumor, high CSF pressure, or nerve swelling

orangey-pink

• when the rim tissue has a white color and is dying
• probably will have positive affarent pupillary deffect (+APD)

impeded blood flow at a vessel crossing

the light reflection of the fovea in the macula

• should be slightly darder than the rest of the retina, free of hemorrhages and pigment
• blood supply of Macula comes from Choroid

• exactly what it sounds like
• causes permanent loss of visual acuity

an area of hyperpigmentation (similar to a mole on the skin)

• a leakage of blood outside of the vessel
• appears as small red spots on retina
• can pool blood in the bottom of the eye

• microinfarcts of the nerve fibers
• swelling of the nerve fibers from occlusion of small arterioles
• appear white and fluffy

fluid leakage that has been reabsorbed leaving a yellow, flat appearance

any break in the retinal layer from trauma, disease, or anatomical variations

• the most PLUS that enables the patient to resolve the best visual acuity possible
• determined subjectively
• 0.25 more plus blurs letters
• 0.25 more minus does not increase clarity of letters

• all the sphere and half of the cylinder algebraically combined together
• sphere + 1/2cylinder = spherical equivalent

• decreasing fog by 0.25 steps until best acuity is achievable
• target is Snellen acuity chart
• stop when no increase in visual acuity is achieved by more minus
• mono or bino

• based on aberrational accommodation or chromatic interval
• decrease fog until chromatic interval is strattling the retina
• use 20/40 to 20/60 row target
• dim lighting
• want equality of clarity of letters in both sides
• still works on color-deficient people
• mono or bino

• there is 0.50D depth of focus, with an additional 0.25D plus causing a fog to the 20/20 row
• target is 20/20 row (cannot perform if patient is not 20/20)
• go three clicks down (0.75D more minus) from first blur out point
• mono or bino

• subjective diagnosis (patient decides what is best)
• use JCC lens
• target is 20/30 or 20/40 row
• refine axis by straddling the axis scoped with the red and white dots, then "chase the red dots"
• if patient runs around, increase cylinder power
• refine power by placing dots on the principle meridians

not like the cylinder correction and "kick out" any attempt to correct it

• quick response means lots of difference in choices
• slow means little difference and close to equality
• no response means patient could be "clueless"

• equally balance accommodation between two eyes
• not balancing acuity
• target is blurred 20/40 line
• use vertical prisms to create two lines and ask which is clearer
• make the two line equally clear or equally blurred
• leave dominant eye clearer if no equallity is acheived