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
