OPTH Lec01 Flashcards
Why is the basic eye exam a crucial skill for the PCP?
1) Evaluate ocular complaints and provide definitive diagnosis and treatment, or appropriate referral 2) Detect blinding eye disease, systemic disease, or CNS disorders 3) Establish a baseline- change from baseline indicates progression or improvement
External Anatomy
ocular adnexa, eyelids, tarsal conjunctiva, bulbar conjunctiva
Globe Anterior Chamber
cornea, limbus, sclera, anterior chamber, iris, lens, ciliary body
Globe Posterior Chamber
vitreous cavity, retina, macula, choroid, optic nerve
Scleral
thick outer coating of globe, usually white and opaque
Conjuctiva
thin, vascular tissue covering sclera (bulbar conj) and inner aspect of the eyelids (palpebral conjuctiva)
Uvea/Uveal tract
made up of iris, ciliary body and choroid
Cornea
provides 2/3 of the refractive power, what you need to see clearly
Lens
provides 1/3 of the refractive power
Emmetropia
eye is the correct length and the image is focused on the retina
Hyperopia
eye is too short and the image is focused behind the retina (see things that are close blurry and things that are far clearly)
Myopia
eye is too long and the image is focused in front of the retina (see things that are nearby clearly but cannot see far)
Astigmatism
refracting power of the cornea is different in one meridian than the other (distorts and blurs)
Presbyopia
When the lens loses its ability to accommodate (become more convex) for near vision. Usually in the mid-40s and the distance visual acuity is not changed but the near visual acuity is. Correct with spectacles, contact lenses. Refractive surgery correct refractive error but doesn’t correct presbyopia.
VA
visual acuity; the smallest object a person can identify at a given distance from the eye
OD
oculus dexter - right eye
OS
oculus sinister - left eye
OU
oculuc utergue - both eyes
cc
with correction
sc
without correction
Why must visual acuity testing be done in children before 7?
because visual cortex locks at 7; shuts down and there can be no more development of visual acuity (see with brain not eyes so it’s important for those pathways to develop)
Name the specific tests and what they are assessing:
1) Confrontational eye testing
2) Color vision testing tests for occupational, retina or optic nerve disease (7-10% of men, red/green, X-linked)
3) Fluorescein staining: to detect a corneal epithelial defect; use a Wood lamp or cobalt blue filter
4) Upper lip eversion - look for superior foreign body
5) Congenital color deficiency - red/green (7-10% of males, x-linked, recessive)
6) Ishihara plates
Who will see this?
Anyone will see a 12 on it
Who will see this?
A right sided dichromate will see a 21
Anterior chamber depth assessment:
indicated when the narrow angle is suspected prior to dilation
Tonometry:
eye pressure, important in glaucoma (normal IOP = 8-21mmHg)
What eye charts would you use?
Rosenbaum for near VA Snellen for distance VA (Snellen defined standard vision as the ability to recognize the symbol (optotype ) when it subtends 5 minutes of arc)
Equipment to test
Fluorescein strips, mydriatic drops (tropicamide 1%) topical anesthetic (proparacaine HCL), Tonometer (optional)
What is visual acuity?
Ability to resolve a certain size object at a given distance Always check first while patient is wearing corrective lenses before you shine light in.
Normal is 20/20 = a normal person standing at feet can see. 20/70 means that a person with 20/20 vision can see what a person with 20/70 can see at 70 feet. So if you have 20/20 you will be able to see the same thing at 70 feet as a person with 20/70 needs to stand at 20 feet to see.
What is considered Normal, moderate low, legal blindness?
20/20 to 20/70 = normal
20/80 to 20/160 = moderate low vision
20/200 or less when corrected with the better eye or less than 120 degree of field = legal blindness; severe low visions Counting fingers = profound low vision Hand motions to no light perception = blind
How to do the visual acuity test?
Patient to stand the proper distance from the chart, test R than L, use correction or pinhole, make sure other eye is properly covered. To attain a line - must correctly identify half or more of the letters. Encourage to guess.
How do you perform an external eye exam?
USE ADEQUATE LIGHT (penlight or ophthalmoscope), inspect lids, surrounding tissues and palpebral fissures, palpate orbital rim or lids. Palpate the preauricular, submandibular or submental lymph nodes IF SOMEONE COMES IN WITH A RED EYE.
How do you perform a pupillary examination?
Darken room, ask patient to fix their gaze on a distant object to avoid the accommodative pupillary constriction. Direct response - light shined in eye. Consensual response - when the light is shined in the other eye. Important because for one optic nerve to function differently from another optic nerve, almost all the time; the damage has to be anterior to the chiasm! Look for alterations of pupil shape (normal is round). Can also have sphincter trauma or sphincter adhesions.
When you are swinging the flashlight during a pupillary examination; what are you looking for?
Afferent pupillary defect (APD or Marcus - Gunn)
Ocular Motility Exam
Have patient follow and object; systematically test each muscle in its primary field of action to detect weakness or paralysis. Use the H.
Ophthalmoscopy
Dim lights, ask patient to stare at a distant object so that their pupils enlarge, set diopter to +10 to get a clear red reflex and look through the aperture. Place hand on forehead, approach the eye at an angle of 15 degrees to the visual axis to visualize the optic disc. Turn the focusing wheel to 0 (or minus) to bring the retina into focus. Follow the retinal blood vessel as it widens toward the optic disc toward the angle of its branches.
Where is the optic nerve located?
15 degrees nasal to the central macula (visual axis - line from fixation target to the central macula)
Where it the optic disc?
Nasal to the fovea
What is the order of an ophthalmoscopy examination?
optic disc, retinal blood vessels, periphery, macula, and fovea.
Red reflex
Reflection of light off the retina. View from a distance and then turn wheel to get a crisp view.
What does a normal red reflex look like?
Evenly colored without shadows
Where is the optic nerve located?
15 degrees nasal to the fovea on the equator of the globe
What does a normal optic nerve look like?
vertically oval and pink
What is the normal average measurement of an optic nerve?
1.5 x 1.7 mm
What is an increased cup to disc ratio an indicator of?
glaucoma or being on an anti-glaucoma medication
Why would you see hypo or hyper pigmented crescents?
the nerve, choroid and RPE joining together. The nerve fibers can be anomalously myelinated.
What is this?
This is a normal optic disc nerve
Central retinal artery branches into?
4 quadrants
Retinal vessels lie where?
in the superficial nerve fibers layer
Where do the 4 quadrants drain to?
central retinal vein
What is the normal artery to vein ratio?
2 to 3
When looking at the optic disk, what are you looking for?
Artery to vein nicking (crossing changes), hemorrhages, heard or soft exudate, and cotton wool spots
Where is the macula located?
2 disc diameters temporally and slightly inferiorly to the optic disc
Macula may have yellowish tint due to what?
xanthophyll pigment
What is the fovea?
A central depression that may become a concave mirror forming the umbo
Why is the Macula darker than the retina?
Because there are taller and more heavily pigmented RPE
How do you perform a confrontation Visual Fields exam?
GREAT screening tool. Done by sitting 1 meter from the patient and physicians L eye looking at the patient’s right eye. Monitor the fixation and prevent either a stationary or moving target (or both)
How do you do an upper lid eversion and why?
To search for conjunctival foreign bodies and other signs. Apply topical anesthetic, have patient look down and grasp the upper lid margin either with thumb and forefinger or a wooden end of a cotton tip applicator and maintain pressure on the eyelid. Remove any foreign bodies if necessary.
How do you assess the anterior chamber depth and what does it tell you?
Perform by shining a light from the temporal side of the cornea. If the light goes across nasally, the nasal iris and sclera crescent are illuminated = safe to dilate. If the light is blocked by the temporal iris and nasal iris and sclera are dark = don’t dilate; refer to ophthalmologist.
How do you perform an eye examination?
- Measure VA in each eye
- Perform confrontational visual field for each eye
- Inspect the lids and surrounding tissues
- Inspect the conjunctiva and sclera
- Test the extra ocular movements
- Test the pupils for direct and consensual responses
- Inspect the cornea and iris
- Assess the anterior chamber for depth and clarity
- Assess the lense for clarity with ophthalmoscope (red reflex)
- Perform ophthalmoscopy
- Determine if a referral is appropriate
