Visial exam and disorders of vision Flashcards
What is shown here?
Superficial flame-shaped hemorrhages,
dot hemorrhages, & microaneurysms in a patient with nonproliferative diabetic
retinopathy
_____ is optic disk swelling caused by increased intracranial pressure
Papilledema
Causes of papilledema
- Space occupying lesion
- Pseudotumor cerebri
- Addison’s disease
- Hypoparathyroidism
- Sleep apnea
- Obesity hypoventilation
syndrome
8 point eye exam includes:
- Visual Acuity (Snellen chart)
- Pupillary exam
- Ocular motility
- Intraocular Pressure
- Visual fields
- External Exam
- Slit-lamp examination
- Fundoscopic exam
What does 20/XX mean anyway?
- Clarity of vision measured at 20 feet
- Eg: 20/100 vision
- Patient must stand as close as 20
feet to see what a person with
normal vision can see at 100 feet
Pupillary Exam
- Swinging flashlight test
- Dim room lights (if possible)
- Patient should focus on an object 15 feet away to avoid the pupil constriction normally seen with accommodation.
A. Pupils are normal & equal before light testing.
B. Both pupils constrict when light is shined into the normal (right) eye.
C. Afferent pupillary defect (Marcus-Gunn pupil) of the left eye when compared with
D. Unaffected right eye
IOP ____ due to ↓ fluid production or loss of globe integrity
↓
IOP ↑ when fluid production > outflow, causing
glaucoma, hyphema
Normal IOP =
10 to 20 mm Hg
Factors that determine depth perception
- Size of the image of a known object on the retina
- Moving parallax phenomenon
- Stereopsis
objects moving at a constant speed across the frame will appear to move a greater amount if they are closer to an
observer (or camera) than they would if they were at a greater distance
Moving parallax phenomenon
The perception of depth produced by the reception in the brain of visual stimuli from both eyes in combination;
binocular vision
Stereopsis
Normal eye or _____
“emmetropic”
Farsighted eye or Hyperopia
- Usually the eyeball is too short or, occasionally, the lens system is too weak
- Parallel light rays are not bent sufficiently by the relaxed lens system to come to focus by the time they reach the retina (capable of focusing distant objects on the retina).
- To compensate, the ciliary muscle contracts to ↑ the strength of the lens
Objects close-up appear blurry, out of focus
Farsightedness
In Farsightedness, Light focuses ____ the retina
behind
Age-related worsening of vision
Presbyopia
Nearsightedness or Myopia
- Ciliary muscle is relaxed & light from distant objects is focused in FRONT of the retina.
- Usually eyeball is too long
- Can result from ↑ refractive power in the lens system of the eye.
- The eye cannot ↓ the strength of its lens less than a relaxed ciliary muscle.
- No mechanism to focus distant objects sharply on the retina.
- As an object moves nearer, the eye can focus the image
Objects in the distance appear blurry, out of focus
Nearsightedness or Myopia
Astigmatism
- Refractive error of the eye causing the visual image in one plane to focus at
a different distance from that of the plane at right angles. - Most often results from ↑ curvature of the cornea in one plane of the eye
Abnormal curvature of the cornea
Astigmatism
T/F Astigmatism causes Blurred vision at any distance
T
Strabismus
Cross-eyed
One eye is turned
* Inward → esotropia
* Outward → exotropia
* Upward → hypertropia
* Downward → hypotropia
Children with strabismus often develop
_____ (lazy eye) & impaired depth
perception
amblyopia
Strabismus Clinical Presentation
- Diplopia (double vision)
- Eye strain
- Headache
- Decreased depth perception
Strabismus diagnosis
- Visual acuity (Snellen Chart)
- Corneal light reflex test
- Cover/Uncover test (1st video-link)
- Retinal bifringence scanning (2nd video-link)
Strabismus Treatment
- Referral to Ophthalmology
- Eyeglasses
- Prism lenses
- Vision therapy
Leading cause of decreased vision among children
Amblyopia “lazy eye”
Strabismic amblyopia
- Foveas of the eyes are presented with two different &
unfusible images. - Visual cortex suppresses the image from one eye in
order to avoid having diplopia - Long-term suppression of one eye → strabismic
amblyopia
Refractive amblyopia
- Foveas of the eyes are presented with different image clarity asymmetric refractive error (anisometropia)
- Often dx’d later, eye abnormalities are less obvious & discovered when children start learning to read
Deprivational amblyopia
- Less common & is the result of visual axis interruption
- Cataracts, ptosis, vitreous hemorrhage, corneal opacities
Treatment for amblyopia involves patching of the ____ eye
unaffected
Keratoconus
Progressive, thinning, cone-shaped protrusion of the cornea → visual impairment
Keratoconus etiology: association with ___
- Down’s syndrome
- Atopic dermatitis
- Retinitis pigmentosa
- Aniridia
- Marfan’s syndrome
- Ehlers– Danlos syndrome
Keratoconus presentation
- ↓ vision: Distortions, glare/flare, & monocular diplopia or ghost images
- Unsatisfactory spectacle correction
- Corneal sensitivity
- Decreased tear secretion
- Bilateral but asymmetric
Deposition of iron in the basal epithelial cells in a (often
partial) ring shape at the base of the conical protrusion
Fleischer ring
What are Vogt striae and when will you see it?
(fine-stress lines) in the deep stroma fluorescein
seen with keratoconus
Keratoconus Tx
- Rigid contact lenses
- Scleral lenses
- Surgical correction
- Referral to opthalmology
