-
AC/A
- Accomodative convergence in prism diopters used by he patient per D of accommodation
- Relationship remains relatively constant
- Changes slightly inside 20cm
-
AC/A is less than 6/1
- Convergence response is less than convergence stimulus
- Gets more exo closer in
-
AC/A greater than 6/1
- Convergence response is greater than convergence stimulus
- Gets more eso closer in
-
Gross value
- Retinoscopy
- Final neutrality in phoropter with working distance included
-
Net value
- Retinoscopy
- Neutral lenses that make patient emmetropic
-
Detection Acuity
The visualization of an object on a background different from the object itself
-
Resolution (VA)
- Ability to just recognize a lateral misalignment on a frontal plane
- Most accurate type of acuity
-
Recognition (VA)
Determination of a threshold of recognition of two or more targets or objects on a contrasting background
-
Contrast Sensitivity
- 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
-
5 minutes of arc
Amount of detail human eye is able to resolve
-
Amblyopia
Diminished VA w/out structural abnormality of eyes or visual pathway, and uncorrectable by optical means
-
Height of letter at 20 ft in Snellen chart
8.73 mm
-
-
-
What causes less spherical and chromatic aberration?
Smaller pupils
-
Size of pinhole for VA?
1 mm diameter
-
Increased VA with introduction of a pinhole means...
Acuity can be increased by refractive means
-
What does lack of increased VA after introduction of a pinhole?
Organic or pathological inhibition
-
Vasc.
Visual acuity without correction
-
Vacc.
Visual acuity with correction
-
Sphere correction/uncorrected VA relationship
- 20/50 = 1.00 D
- 20/100 = 1.50 D
- 20/200 = 2.50 D
-
Anisometropia
Different refractive powers in the eyes of one patient
-
What is broken while performing cover test?
Fusion
-
Unoccluded eye moves when paddle is presented in cover test
Tropic patient
-
Uncovered eye turns in during alternating cover test
Exophoric patient
-
How do you quantify phorias and tropias?
Adding prism to eyes
-
Patient sees paddle and object moving in same direction during cover test
Exo diagnosis
-
Base out prism
- Brings image in for all
- Manages esophoria and esotropia
-
Pituitary lesion causes
Temporal vision loss
-
Quadrantanopsia
1/4 of the visual field gone in one eye
-
Hemianopsia
1/2 of visual field gone in one eye
-
Homonymous
Both eyes involved, same side
-
Scotoma
Isolated area of visual field loss
-
Glaucoma
- Intraocular pressure causing a degeneration of the ptic nerve
- Nerves must be degrading in order to be diagnosed
-
Facial Amsler test
- Checks for macular defects
- Chin is 10 degrees
- Ears are 5 degrees
-
Extraocular motilities test
- Evaluates cranial nerves 3, 4, & 6
- Evaluates fixation
- Evaluates bony orbit
-
Hering's of Equal Innervation
Both members of a yoke pair receive equal innervation
-
Pursuits
- 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
-
Rotations
- Test binocularly
- Monocularly if restricted
-
Saccades
- Test binocularly
- Monocularly if abnormal
-
Complete third nerve palsy
Eyes are positioned down and out
-
Complete sixth nerve palsy
- Affected eye is turned in due to relaxation of lateral rectus
- Susceptible to: diabetes, toxins, alcohol
-
Fast crisp constriction of pupil
Recorded as 4+
-
Slow, sluggish constriction of pupil
Recorded as 1+
-
Corectopia
A misplaced pupil
-
Anisocoria
Unequal pupil size
-
Miotic
- Small, constricted pupil
- Also a drug classification Of a substance that constricts the pupil
-
Mydriatic
Drug classification that dilates pupil
-
Direct light reflex
The constriction of the pupil to light, as observed in the illuminated eye
-
Consensual light reflex
The constriction of the pupil to light, as observed in the fellow eye
-
Sphincter muscle
- Iris muscle responsible for constriction
- Parasympathetic innervation
-
Dilator muscle
- Iris muscle responsible for dilation of pupil
- Sympathetic innervation
-
Accommodative/Near reflex
The constriction of the pupil in response to acommodation or a near stimulus
-
Marcus-gunn reflex
- Paradoxical dilation to a bright light stimulus
- Sign of optic nerve disease
- Also called afferent pupillary defect (APD)
- Poorer direct response than consensual
-
Pupillary pathway
- Optic tract
- Pretectal nucleus
- Edinger-Westphal Nucleus
- Cranial nerve 3
- Ciliary ganglion
- Inferior branch of Cranial nerve 3
- Sphincter
-
Amaurotic pupil
Manifested in eye with no light perception
-
Argyll-Robertson Pupil
- Small, irregular pupils, which do not react to light, but do have positive accommodation response
- Caused by syphilis, diabetes, alcoholism, and mid-brain tumors
-
Aide's Tonic pupil
- Benign
- Dilated pupil
- No immediate response to bright light; some after prolongued exposure
- Unilateral
- Common in females 30-50s
-
Horner's syndrome
- Ptosis, miosis, anhydrosis
- Affected pupil will not redilate quickly after bright light exposure
-
Presbyopia
Loss of accommodation due to age
-
Amplitude of Accommodation
The maximum ability to accommodate of a person
-
Most comfortable amount of accommodation to use
Half of amplitude o accommodation
-
Minus lens
Pushes light back; more makes you blurry
-
Plus lenses make a myope...
Worse
-
Punctum Remotum
The far point of clear vision with accommodation relaxed
-
Punctum Proximum
The nearest point of clear vision
-
Tonic Accommodation
Resting state of accommodation
-
Psychic accommodation
Stimulation of accommodation caused by the nearness of a target
-
Reflex accommodation
Automatic response to blur
-
Aberrational accommodation
- Range in accommodation due to chromatic aberration
- Varies on power depending on color
-
Excessive accommodation
Constant parasympathetic stimulation of accommodation when there is no need to accommodation
-
Spasm of accommodation
Ciliary muscle is in a state of spasm
-
Tonic spasm
Prolonged, uniform spam of accommodation
-
Cycloplegic/Mydriatic
- Drug that paralyzes accommodation and causes pupil dilation
- Bottled with RED caps
-
Anisometropia
Condition where refractive conditions are not the same for the two eyes
-
Antimetropia
Specific anisometropia where one eye is myopic and the other eye is hyperopic
-
Biocular
- Each eye focussing on object
- Double vision
-
Binocular
- Two eye focussing on object
- One image
-
Stereopsis
- Highest level of binocular vision
- Having depth perception
-
Keratometer
- Objectively measures curves of the cornea
- Indicates cylinder power and axis
- Tests corneal integrity
- Used exclusively in contact lens patients
-
Precorneal film
- Outer oil layer
- Aqueous middle layer
- Mucin inner layer
-
Epithelium of Cornea
- 5 cell layers thick
- Very fast regenerating capabilities
-
Bowman's Membrane of Cornea
- Basement membrane that epithelium adheres to
- Scarring occurs if penetrated
-
Stroma of Cornea
- Bulk of cornea mass
- Maintains cornea shape
-
Descement's Membrane of Cornea
Membrane the endothelium adheres to
-
Endothelium of cornea
- Corneal pump gets rid of edema
- No recovery if damaged
-
Calibrate Keratometer
- 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
-
Extend Keratometer range
- Too steep cornea: place +1.50 lens of central aperture
- Too flat: place -1.00 lens in front
- Consult conversion table
-
K
Flattest meridian of the cornea
-
Cornea flatter than 42.00
Hyperopia
-
Cornea steeper than 44.00
Myopia
-
With the rule astigmatism
- Most converging power in vertical meridian
- Use minus cylinder axis 180 to correct
-
Exo diplopia
- Heteronymous
- OD image is left
- OS image is right
-
Eso diplopia
- Homonymous
- OD image is right
- OS image is left
-
-
Second degree fusion
- Binocular
- No depth perception
-
Third degree fusion
Depth perception, or stereopsis
-
Monocular depth perception cues
- Relative size
- Light and shade
- Overlap
-
Binocular depth perception cues
- Disparity between two images
- Eyes stimulated at corresponding points of fovea
-
Global Stereopsis
- Disparity of visual field evaluated without monocular cues
- More sensitive
- Have to be binocular w/ bifoveal vision
- Tested w/ shapes of the Randot test
-
Local Stereopsis
- Presence of smaller, more localized object
- Aided by monocular cues
- Less sensitive
- Tested by Wirt circles
-
Stereoacuity
- Measured in "seconds of arc"
- Best measurement is 20'
-
Factors affecting Stereopsis
- Binocularity (do they have it)
- Refractive error (especially large anisometropia)
- Strabismus
- Age
-
Cones
Responsible for color vision
-
Erythrolabe
Long wavelength sensitive protein
-
Chlorolabe
Medium wavelength sensitive protein
-
Cyanolabe
Short wavelength sensitive protein
-
Congenital color defect
- Usually red-green
- 8% of males
- 0.5% of females
-
When testing color defects ___ is critical
- Lighting
- Monocular testing
-
Acquired color defects
- Usually result of disease
- Blue-yellow defect
- Can be monocular
-
Protonopia
Do not see red
-
Deuteranopia
Do not see green
-
Tritanopia
Do not see blue
-
Amsler grid
- 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
-
Scotoma
- Loss of vision due to malfunction of photoreceptors
- Black areas reported
-
Relative Scotoma
- Decreased sensitivity to light
- Dim vision
- Reports blur or graying vision
- Hard to see areas
-
Metamorphopsia
- Disturbance to light caused by physical change in retina
- Distortion of vision
-
Adnexa
accessory structures and organs of the eye; e.g., eye brows, skin around orbit
-
Orbit
bony orifice in which the eye ball sits
-
L.L.L.
lids, lashes, lacrimal system
-
Hordeolum
staph infection of lid glands, with pus, pain, and redness
-
Chalazion
sterile clogging of lid glands, with no pus, pain, or redness
-
Ptosis
drooping of eye lid
-
Lagopthalmus
eye lids do not completely close
-
Entropion
in-turning of lids
-
Extropion
out-turning of lids
-
Blepharochalasis
drooping of skin of the eyelids
-
Xanthelasma
- lipid deposit in the skin of the eyelid
- do blood tests
-
Eye lashes
normal lashes are in proper placement without any deposits or foreign substances at the base of the lashes or throughout lashes
-
Blepharitis
inflammation of eyelid margins and lashes
-
Madarosis
loss of eyelashes
-
Trichiasis
in-turning of lashes
-
Meibomianitus
inflammation of the Meibomian glands at the base of the lash
-
Dacryocystitis
infection of the lacrimal sac with swelling and redness near the nose
-
Dacryodenitis
inflammation of the lacrimal gland, with swelling and pain in the area of the lacrimal gland
-
Palpebral conjunctiva
conjunctiva that lines the lids
-
Bulbar conjunctiva
conjunctiva that overlies the sclera
-
Injection
- the amount of redness or vascularization
- recorded as 1+-4+
-
Follicle
white to yellow, translucent avascular elevation of the conjunctiva
-
Papilla
vascularized clear conjunctiva elevation, often giving a velvety appearance to the affected area
-
Pinguecula
- a hyperplasia of the conjunctival tissue, usually in respones to environmental irritation
- prevention is key
-
Pterygium
- a degeneration of the bulbar conjunctiva involving the cornea
- prevention is key
-
Sub-conjunctival hemorrhage
a hemorrhage that causes great alarm in patients by the overall appearance of the conjunctiva
-
Chemosis
- swelling of the conjunctiva
- often an allergic response
-
Sclera
normal sclera is white with few blood vessels seen
-
Episcleritis
- an inflammation of the outer layer of the sclera with pain in the red area
- arthritic patients are predisposed
-
Corneal scar
when a foreign object has penetrated the first five layers of the cornea, into the stroma
-
Arcus senilis
a cholesterol deposit in the periphery of the cornea
-
Keratitis
inflammation of the cornea
-
Tears
- tear break up time should be about 10 seconds
- measured by using fluorescein dye instilled into the lowe cul-de-sac
-
Anterior Angle
- where the aqueous drains
- size is graded from wide open (4+) to closed (0+)
-
Cells
white blood cells in the aqueous
-
Flare
smoky appearing precipitate of protein leaked from inflamed blood vessels
-
Iris
normal iris should have uniform color (sort of)
-
Corectopia
misplaced pupil
-
-
Iritis
inflammation of iris
-
Cataract
- an opacity of the crystalline lens
- about 400 different kinds
-
Aphakia
no crystalline lens
-
Pseudophakia
artificial lens implant
-
Vitreal Floaters
- remnants of hyaloid artery
- always there, but stiff vitreous keeps them out of the way; as vitreous ages, they can move around more
-
Location of Optic Nerve
toward the nose (medial) portion of the back of the eye
-
Cup-to-disc ratio
- 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
-
Papilledema
- pathological elevation of the disc margins
- could mean brain tumor, high CSF pressure, or nerve swelling
-
Rim tissue color
orangey-pink
-
optic nerve atrophy
- when the rim tissue has a white color and is dying
- probably will have positive affarent pupillary deffect (+APD)
-
Constriction
impeded blood flow at a vessel crossing
-
Foveal Light Reflex (FLR)
the light reflection of the fovea in the macula
-
Color of Macula
- should be slightly darder than the rest of the retina, free of hemorrhages and pigment
- blood supply of Macula comes from Choroid
-
Macualr Degeneration
- exactly what it sounds like
- causes permanent loss of visual acuity
-
Nevus
an area of hyperpigmentation (similar to a mole on the skin)
-
Hemorrhage
- a leakage of blood outside of the vessel
- appears as small red spots on retina
- can pool blood in the bottom of the eye
-
Cotton-wool
- microinfarcts of the nerve fibers
- swelling of the nerve fibers from occlusion of small arterioles
- appear white and fluffy
-
Exudates
fluid leakage that has been reabsorbed leaving a yellow, flat appearance
-
Lesion
any break in the retinal layer from trauma, disease, or anatomical variations
-
Manifest Refraction
- 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
-
Spherical equivalent
- all the sphere and half of the cylinder algebraically combined together
- sphere + 1/2cylinder = spherical equivalent
-
Step Down Technique
- 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
-
Red-Green Technique
- 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
-
Three Click Blur Out Technique
- 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
-
Cylinder Power Technique
- 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
-
Patients with long-standing large amounts of uncorrected cylinder will...
not like the cylinder correction and "kick out" any attempt to correct it
-
JCC choices
- quick response means lots of difference in choices
- slow means little difference and close to equality
- no response means patient could be "clueless"
-
Biocular Aniso Balance
- 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
|
|