CM- Extraocular Muscle Dysfunction & Systemic Disease

Question 1

What is amblyopia?
When does it develop?
After what age is treatment rarely effective?

Answer 1

Amblyopia is “lazy eye”. It is a loss of visual acuity not correctable by glasses in an otherwise healthy eye.
It develops in infancy or early childhood.
Treatment is rarely effective if initiated after the age 10.

Question 2

What are the 3 main types of amblyopia?

Answer 2

1. refractive - uncorrected refractive errors
2. occlusion - opacities of ocular media [congenital cataracts, corneal scarring]
3. strabismic - eyes are misaligned due to CN palsies or non-paralytic causes

Question 3

What is the cause of refractive amblyopia?
What happens when there is marked difference between the 2 eyes?
How is this disorder detected?
What is treatment?

Answer 3

Refractive amblyopia is due to uncorrected refractive errors.
If the refractive error is way worse in one eye, the better eye will be “preferred” and the visual pathways will not develop in the poorer eye.

Detection: eyes will look aligned so you need to detect it with the VISUAL ACUITY TEST
- visual acuity screening at 3, again when starting school

Treatment:

1. glasses
2. if visual acuity persists after 4-8 wks, occlude the child’s “good eye” with a patch to force the brain to use the “bad eye”

Question 4

What is the cause of occlusion amblyopia?
How is diagnosis made?
What is treatment?

Answer 4

Occlusion amblyopia is when opacities of the ocular media [cataracts, corneal scarring] prevent adequate sensory input to the retina, disrupting vision development.

Diagnosis: check newborns for media opacities with red reflex

Treatment: remove media opacity [amblyopia may persist still]

Question 5

What is the cause of strabismic amblyopia?
How is diagnosis made?
What is treatment?

Answer 5

Strabismic amblyopia occurs when the eyes are misaligned due to:
1. CN palsy affecting extraocular muscles
2. non-paralytic [more common with children]
Newborns can cross in [esotropia] or out [exotropia] and only get aligned after a few months.

Diagnosis: centration of corneal light reflex checked by pediatricians in the early months of a child’s life

Treatment:

1. patch the good eye and force the brain to use the bad eye
2. treat refractive errors with glasses [esotropia causes hyperopia]
3. surgical realignment

Question 6

What happens if patching is overdone when treating a child with amblyopia?

Answer 6

the patient may develop occlusion amblyopia in the previously good eye

Question 7

How does strabismus in childhood and adulthood differ?

Answer 7

Childhood:

• brain suppresses vision in deviated eye so there is NO diplopia
• amblyopia may develop
• usually non-paralytic

Adulthood:

• diplopia
• neurologic causes [CN3,4,6 palsies]

Question 8

Parasympathetic fibers innervating the pupillary sphincter muscle and ciliary muscle are in what location?
Where do fibers responsible for the control of extraocular muscles lie?

Answer 8

pupillary sphincter and ciliary muscle parasympathetic fibers wind around the periphery of CN3.
Fibers for movement of MR,SR,IR, IO, levator palpebrae lie more centrally

Question 9

If a patient presents with a blown pupil and poor control of CN3 extraocular muscles, what should this be considered secondary to until proven otherwise?
What tests do you need to do to verify?

Answer 9

Pupil-involving CN3 palsies are assumed to be secondary to aneurysm until proven otherwise

1. MRI with contrast or MRA with attn at circle of Willis
2. carotid angiography if initial results are negative but there is high degree of suspicion.

Question 10

A 50 year old patient has difficulty moving his eye inward, out and up, out and down, and in and up. The pupillary reflexes are intact.
What is the likely problem? What is this often due to?

Answer 10

Ischemic CN3 palsy - often due to diabetes

Question 11

An adult patient presents complaining of double vision. They have esotropia.
What CN palsy do they likely have and what are the common causes of this palsy?

Answer 11

CN6 palsy
Esotropia means the eye goes inward, and CN6 controls the LR. If the LR does not work, the eye will go inward.

Causes:

• trauma
• increased ICP where it enters the cavernous sinus
• diabetics

Question 12

A patient has had recent head trauma and now presents with vertical double vision. What is the most likely CN palsy?

Answer 12

isolated CN4 palsy [no SO function]

*vertical misalignment is frequently subtle and difficult to see on routine exam

Question 13

What is the initial stage of ocular disease associated with diabetes?
What will you see on the retina?
When will patients at this initial stage experience visual loss?

Answer 13

Nonproliferative diabetic retinopathy

1. retinal microaneurysms
2. dot/blot hemorrhages
3. hard exudates
4. macular edema

Patient will only experience vision loss at this stage if there is macular edema which thickens the retina and causes blurring

Question 14

Describe the progression from non-proliferative diabetic retinopathy to proliferative retinopathy.

Describe the features in proliferative retinopathy that leads to retinal detachment and blindness

Answer 14

1. Microvascular occlusions lead to retinal ischemia
2. cotton wool spots appear
3. dying retina –> VEGF
4. VEGF induces proliferation of new vessels
5. neovascularization extends from the retina into the vitreous
6. new vessels are fine and friable and rupture easily causing vitreous hemorrhage
7. recurrent vitreous hemorrage and fibrous tissue lead to contraction which causes retinal detachment/blindness

Question 15

What is the best treatment for diabetic retinopathy?

Answer 15

Prevention!
Better diabetic control [measured by HbA1c] decreased the incidence
Get eye exams annually

Question 16

What treatment is done for clinically significant macular edema from diabetes?

Answer 16

Focal laser photocoagulation - seals leaking microaneurysms to decrease retinal thickening

Question 17

What treatment is done for proliferative diabetes?

Answer 17

1. Peripheral retinal laser photocoagulation - converts dying, VEGF producing peripheral retina into dead retina so that they cannot make stimulus for neovascularization
   Macula is spared to spare central vision
2. anti-angiogenic drugs injected into the eye treat w/o collateral damage to the retina

Question 18

What does prolonged systemic hypertension accelerate in the eyes?
How does this manifest on a retinal exam?
Describe normal, early, late appearance.

Answer 18

Prolonged hypertension causes accelerated arteriole sclerosis.

Normal = light streak is reflected by convex arteriole wall [look dark]
Early arteriole sclerosis = light streak broadens and occupies most of the width of the vessel [grey]
Late arteriole sclerosis= light reflex is obscured completely and the arteriole appears white

In addition to arteriole changes, you should also see:

1. venule nicking or abrupt right-angle changes
   - bc arterioles and venules share a sheath where they cross and the thickened arteriole compresses the venule
2. focal narrowing and attenuation of vessels

Question 19

What 4 ocular changes are seen with an acute rise in BP [diastolic >120]?

What change is seen in the most severe form of hypertensive retinopathy due to malignant hypertension?

Answer 19

1. exudate in the retina
2. cotton wool spots
3. flame-shaped hemorrhage
4. macular edema

Most severe = papilledema

Question 20

A patient has exudate in the retina, cotton wool spots, flame-shaped hemorrhage and bilateral papilledema. This patient has malignant hypertension. How should they be treated?

Answer 20

BP should be lowered in a controlled way because a sudden drop in tissue perfusion can result in ischemic optic neuropathy.

Question 21

What ocular changes are seen with hyperthyroidism/Graves?

Answer 21

1. retraction of upper and lower lids [thyroid stare]
2. unilateral or bilateral proptosis/exophthalmos
3. eyelid edema and congestion of conjunctival vessels
4. diplopia due to extraocular muscle involvement
5. vision loss of optic nerve gets compressed by the accumulation of GAGs

Exophthalmos and lid retraction leads to exposure keratopathy [foreign body sensation, dryness of cornea]

Question 22

Sarcoidosis is a chronic multisystem disease characterized histologically by ___________________________. It can affect any age, sex or race, but has a propensity for ___________________.

Answer 22

focal, noncaseating granulomas

black women between 20 and 40

Question 23

What lab findings are associated with sarcoidosis?

What is diagnostic?

Answer 23

1. elevated ACE
2. elevated lysozyme
3. abnormal chest x-ray with bilateral hilar lymphadenopathy

Biopsy is diagnostic.

• easiest tissue to biopsy is conjunctiva when granulomas are present
• 2nd is lacrimal gland
• if neither yields the diagnosis but there is high suspicion, mediastinal or transbronchial biopsy of lymph nodes

Question 24

What are the ocular manifestations of sarcoidosis?

What are the signs/manifestations of neurosarcoidosis?

Answer 24

Sarcoidosis is a common cause of:

1. anterior uveitis [irisitis]
2. posterior uveitis with:
   - retinal involvement [vasculitis, hemorrhage, neovascularization]
3. dry eye syndrome if the lacrimal gland is involved

Neosarcoidosis is 2x as common if fundus is involved.

1. optic neuropathy
2. CN palsies

Question 25

What is the most common malignancy that affects the eyelids?

How does it present?

Answer 25

Basal cell carcinoma is the most common malignancy on the eyelid and causes abnormal, scaly, erythematous or nodular lesion.

It could also be squamous cell carcinoma or sebaceous carcinoma

Question 26

Describe retinopathy from HIV.

Answer 26

microthrombi from antigen-antibody complexes and fibrin cause retinal capillary occlusion resulting in:

1. retinal hemorrhage
2. cotton-wool spots

Question 27

What is the leading cause of vision loss in patients with AIDS? [over 25%]
What is the characteristic ophthalmologic appearance?
What can halt the progression of destruction?
What is a sequelae?

Answer 27

CMV retinitis is the leading cause of visual loss.

1. hemorrhagic retinal necrosis
2. white brush border at the junction of normal and affected retina [cottage cheese and catsup]

antivirals- ganciclovir can halt progression of retinal destruction

Sequelae- necrotic retina has many holes –> retinal detachment

Question 28

What are the 4 most common causes of retinitis in HIV patients?

Answer 28

1. CMV [most common]
2. toxoplasmosis
3. syphilis
4. herpes