Posterior Segment Examination - Week 1 Flashcards
Why dilate?
- improved view of retina
- for binocular viewing: enhanced image quality
- for better detection of diseases
Indications for dilating:
- new patient
- routine every 2 years
- flashes and/or floaters
- unexplained vision loss/reduction
- progressive retinal diseases
- systemic conditions
- hx of: head injuries, ocular trauma, chronic uveitis, peripheral retinal degen., ocular surgery
- refractive error: myopia to high myopia, and hyperopia (and anisometropia)
- limited view of posterior pole
Way to remember:
“New systemic routine flashes are progressive and unexplained. Check patient’s refractive error and history for disease and injury”
How often should you routinely dilate a patient? (Given no other problems)
Every 2 years
Why should you dilate if the patient has flashes and/or floaters
Flashes/floaters are caused by anything that can pull on the retina or vitreous
Are flashes/floaters an urgent issue?
Yes
Name an example of a progressive retinal disease:
Diabetic retinopathy
List some examples of systemic conditions:
- hypertension
- high cholesterol
- any autoimmune disease
What could sudden vision loss be a sign of?
Stroke
How often should you dilate/post eye exam for patient’s who had ocular surgery?
Yearly
How often should you dilate a moderate to high myopia patient?
3-7D: every 2 years
8D +: yearly
What is one reason for limited view of posterior pole of the eye?
Cataract
Define cycloplegia
Is paralysis of the ciliary muscle of the eye, resulting in a loss of accommodation
Considerations for dilation/posterior segment examination
- Hx
- V.A (vis. Acuity) (subj. refraction needed or just pinhole)
- pupils testing
- Accommodation tests
- Assess potential for angle closure
- After DFE, warn patient about angle closure symptoms
**
Accommodate your pupils to assess angle of history and V.A
How can you assess potential for angle closure?
- angle: VH (Van Herick) technique
- iris bowing: iris shadow test
- depth: smith’s method
- structures: gonioscopy
- Anterior OCT (optical coherence tomography)
- IOP
Contraindications for dilating:
- Angle Closure Glaucoma
- Px using pilocarpine for Tx of glaucoma
- dislocation of crystalline, or IOL lens
- iris fixed or anterior chamber IOL
- Hyphema (blood in AC)
- Acute corneal diseases
- hypersensitivity to mydriatic eye drops
Way to remember:
*dislocate the px’s iris at a fixed angle to treat acute hypersensitivity and Hyphema
Or DIPHAHA
What are the question mark contraindications for dilation:
I.e there is some digression on whether you don’t dilate
- pregnancy/lactation
- narrow AC angle
- recent ocular injury
- petite/anorexic individuals
- kids/children –> liver enzyme activity
- sick/febrile
- way to remember
Sick pregnant petite kids are sick and narrow
Via what 2 main methods can you dilate? Which is more powerful/effective?
- dilator muscle agonist
- sphincter muscle antagonist
Sphincter muscle antagonist is more effective (because sphincter is the stronger muscle)
True or false: sympathomimetics (dilator agonists) cause cycloplegia
False
True or False: Sphinctor antagonists/anti-muscarinic drugs can cause cycloplegia
True
Which muscle, when innervated, results in sectoral dilation of the pupil? (Pear-shaped pupil)
Dilator muscle
Sphincter does not, instead, sphincter muscle innervation gives max dilation
Effects of dilator muscle innervation:
What is unaffected?
- sectoral dilation of the pupil (sectoral mydriasis)
- widening of palpebral fissure
Pupillary light reflex = unaffected
How long does mydriasis take to start and duration after dilator muscle innervation? When is it maximal?
Starts in 10 minutes
Is maximal after 60-90min
Can last for 5-7 hours
(Or even 12-24 hours)
What drug do we use to innervate the dilator muscle to cause mydriasis?
Phenylephrine 2.5% and 10%
What happens to the pupillary light reflex when you innervate the dilator muscle? What about the sphincter muscle?
Dilator: nothing happens
Sphincter: pupillary light reflex is reduced or abolished
Does dilator muscle innervation affect accommodation? What about sphincter?
Dilator: no
Sphincter: yes. It does affect accommodation. Causes cycloplegia, resulting in a loss of accommodation
Which drugs are used as sphincter antagonists to dilate the pupil?
Tropicamide 0.5%, 1%
Cyclopentolate 0.5%, 1%
Atropine 1%
Homatropine 2%
Remember by saying HCAT
Which drug is the drug of choice for optometrists for dilating pupils? Why? Is it a dilator agonist or sphincter antagonist?
Tropicamide 0.5%, 1%
- due to its safety profile
- it’s a sphincter antagonist
Is dilator symp or para? What about sphincter?
Dilator: innervate by Sympathetic
Sphincter: Parasympathetic
How long is the onset and duration for tropicamide?
Quick onset and short duration
How much tropicamide do you apply for DFE (dilation)? How much do you apply for inducing cycloplegia?
DFE: 0.5%
Cycloplegia: 1%
Can you apply a 2nd drop of tropicamide? If so, when?
If needed, apply 5 minutes after 1st
What drug is often used for cycloplegia?
Cyclopentolate
- note: patient asked to attend 1 hour before appointment
Rank the systemic adverse affects from worst to least for the following:
- tropicamide
- cyclopentolate
- Atropine
1/ Atropine
2/ Cyclopentolate
3/ Homatropine
How long do the effects of Atropine last?
For days to weeks
Which drug is used in amblyopia treatment?
Atropine
- put atropine in good eye to make it blurry. This forces the lazy eye to work
What can Homatropine be used for? (Other than dilation)
- used to prevent or breakdown posterior synechiae
Posterior synechiae = when the iris attaches to the lens or cornea
- this causes it to be sticky and closes the anterior chamber
What is the use of Alcaine?
Local anaesthetic
True or false: Alcaine does not sting on installation
False. Alcaine stings VERY BADLY
Why isn’t Alcaine used on a long term basis?
Due to epithelial toxicity; can impair epithelial healing
What is an effect of Alcaine on the cornea?
Increases corneal permeability
For all drugs used, what should you check for and record:
- Px allergy
- Any known side effects
- Label, concentration, expiry date
