CM- Physical Exam of the Eye Flashcards
What are the 8 parts of a general eye exam?
- visual acuity
- external examination
- pupillary reactions
- ocular motility and alignment
- visual fields
- anterior segment examination
- intraocular pressure
- funduscopic examination
What 4 symptoms raise index of suspicion for a more serious sight threatening disorder?
- decrease of vision
- photophobia
- diplopia
- deep aching ocular pain
What 6 signs raise the index of suspicion for a serious sight-threatening disorder?
- decreased vision
- corneal edema
- corneal ulcers/infiltrates
- circumcorneal redness
- abnormal pupil
- elevated intraocular pressure
What 3 pieces of equipment are necessary to perform an adequate eye exam?
- visual acuity chart [or card]
- light source [penlight]
- direct opthalmoscope
*access to mydriatic drop, tonometer, pair of loupes or slit lamp would further enhance
What must light focus on to achieve sharp, clear central vision?
fovea of the retina
What 2 structures of the eye provide refractive power to help focus light onto the fovea?
2/3 of refractory power comes from the cornea
1/3 comes from the lens
What is myopia, hyperopia, and astigmatism?
Myopia- the eye is too long, so visual acuity is lost at far distances
Hyperopia- the eye is too short, so visual acuity is lost at short distances
Astigmatism- of the refracting power is different in one meridian than another [ex. horizontal and vertical don’t agree] then vision will be blurry
What is accommodation?
Describe the process of accommodation.
What is it called when accommodation is lost with age?
Accommodation is the ability of the lens to assume a more convex shape in response to ciliary muscle contraction.
When looking far way, the cililary muscles are relaxed, and the zonules are tighted flattening the lens.
When changing to look at something closer, the ciliary muscles contract, zonules relax, and the lens curves [convex]
Presbyopia is the loss of accommodation with age and usually manifests around 40
Describe the proper technique for Standard Snellen visual acuity.
- Patient should be wearing corrective lenses and you should make them cover one eye to test each eye individually
- Distance visual acuity is preferred and the chart is at 20 feet from the patient.
- patient reads the smallest letters/numbers they can
- results are recorded as 20 over whatever number [20/40 means that this person can read at 20ft what a normal person can read at 40]
- patient gets credit if they can read 1/2 the line - if the patient cannot see the largest letter on the chart, they are asked to count the examiners fingers at 5ft
- if the patient cannot see the fingers, they are asked to detect motion [wave of examiners hand] at 10ft
- if patient cannot detect hand movements, the examiner uses penlight to see if patient can detect light [LP or NLP =light perception or no]
If you cannot do a standard snellen with distal visual acuity, how do you perform with a pocket visual screener?
The card provides “near-equivalent” Snellen acuity
- wear corrective lenses [and if over 40 bifocals]
- hold card 14 to 16 inches from face
- test each eye individually
Why is is crucial to test each eye individually for Snellen visual acuity tests?
Testing both eyes together would mask unilateral vision loss
What are 4 common lid abnormalities that should be able to be diagnosed on visual examination of the eye?
- entropion - the lid is turned inward and the lashes rub against the ocular surface
- ectropion - lid is turned outward, tears flow onto cheeks; conjunctiva is dry and keratinized
- Ptosis - drooping of one or both eyelids
- isolated [congenital, acquired]
- neurologic or systemic disorder [Horner’s, 3rd nerve palsy] - retraction- seen with Graves
Systemic diseases can be associated with signs on the ocular adnexa [orbit, conjunctiva, eyelids]. What are 2 examples?
- Xanthelasma- benign histiocytic tumor that has cholesterol laden macrophages. It presents as yellow plaques underneath the medial canthal area
- Proptosis- forward displacement of the eye, and lower lid edema are signs of Graves
Describe the anatomy of the pupillary reflex.
[how does information of light travel]
- light strikes one eye, and the info is carried posteriorly through the optic nerve
- Half the fibers decussate at the optic chiasm into the contralateral optic tract, half stay in the ipsilateral optic tract
- 2/3 along the optic tract, some fibers leave and enter the superior colliculus and go to the pretectal nucleus.
- From the pretectal nucleus, information passes to Edinger-Westphal nucleus bilaterally
- From here pupillary motor commands travel with the 3rd CN through the superior orbital fissure to the ciliary ganglion and iris sphincter.
- Iris sphincter constricts to make the pupil smaller
LIGHT SHINED IN ONE EYE SHOULD TRANSMIT TO BOTH PUPILS EQUALLY
How do the sphincter of the iris [constrictor] and dilator of the iris differ in terms of innervation?
Constrictor is a parasympathetic response from EW nucleus in the midbrain
Dilator is sympathetic
Describe the pathway for eye dilation.
- first order neurons are in the hypothalamus
- course down the brainstem to cilio-spinal center of Budge [C8-T2]
- Second order neurons exit spinal cord, cross apex of the lung, and end at superior cervical ganglion
- third order neurons ascend with common and internal carotids to join the opthalmic artery in the carvernous sinus –> iris dilator muscle
What 3 features are associated with the near synkinetic response?
- convergence - eyes rotate towards each other
- accommodation - lens becomes convex
- miosis- pupil shrinks
How do the pathways for light induced pupillary constriction and near synkinetic pupillary constriction differ?
Light–> optic tract –> pretectal nucleus–> EW
Near–> peristriate cortex [more ventral in the midbrain then the light reflex pathway] –>EW
Both near and light have a common final pathway from EW nucleus via 3rd cranial nerve through ciliary ganglion to the iris sphincter muscle
