Opthalmic Examination 2

Question 1

Potential changes to anterior chamber visable on slit exam

Answer 1

• Tydall Effect (Aqueous Flare)
• Keratic precipitates
• Hyphema (Blood)
• Hypopion (Pus)
• Posteria Synechia (Iris adhered to lens, cannot move d/t protein exudate etc. can affect PLR)
• anterior lens luxation
• anterior presentation of the vitreous
• protein in anterior chamber -> protein clumping eg. with FIP

Question 2

What is posterior synechia?

Answer 2

• iris attached to lens and cannot move d/t iris exuding protein

Question 3

Where is the aqueous humour produced?

Answer 3

Ciliary body - swirls into anterior chamber then drops ventrally d/t gravity and cooling action

Question 4

What occurs 2* to protein accumulation

Answer 4

Keratic precipitates

Question 5

What are the 2 main objectives of an ophthalmic exam and which light examination techniques are used?

Answer 5

1. differentiate nuclear sclerosis from cataracts: DDO (distant direct observation)
2. examine posterior segment: CDO, IO (close direct observation, indirect observation) Mostly retina, lens and vitreous too

Question 6

How does nuclear sclerosis appear on DDO? DDx?

Answer 6

• Pupil bluish, refracts light but does not black
• Ddx: cataracts block light completely
  NB: can become a cataract with time in humans but smallies usually do not live long enough

Question 7

What shape are cataracts?

Answer 7

ANY SHAPE!!!!

Question 8

What type of image is created with indirect ophthalmoscopy?

Answer 8

Inverted L-R and upside-down. Virtual image. Large field of view but LOW magnification

Question 9

What is the neutral setting? What else can the number wheel on an ophthalmoscope be used for?

Answer 9

• neutral setting usually 0, unless wearing glasses, and indicates focus on the fundus
• Increasing numbers (+20) brings field of vision closer to eye piece (ie. though posterior chamber, lens, into anterior chamber and cornea
• +10 - +15 = lens

Question 10

Aim of DDO?

Answer 10

(distant direct observation)
- use tappetal reflection (fundus reflex)
> nuclear sclerosis appears as milky and cloudy before tappetal reflection (but can still shine through)
> cataracts appear as black shadows upon retroillumination of the lens (Golden/green background) §

Question 11

How is CDO carried out?

Answer 11

(Close direct observation)

• find optic disk
• divide into quarters
• mental collage
• all blood vessels lead to the optic disk

Question 12

What equipment is needed for indirect observation?

Answer 12

• Ophthalmoscope for light
• 15-20-30D lenses (and panoptic opthalmoscope, v expensive referral only)
  > larger diopter power = lower magnification, ^ field of view

Question 13

What condition causes degeneration of blood vessels and darkening of the optic disk?

Answer 13

progressive retinal atrophy (PRA)

Question 14

What additional tests can be carried out as part of an ophthalmic exam?

Answer 14

• fluoroscein for ulcers and nasolacrimal duct patency
• IOP (tonometry) 12-22mmHg
  > ^ = glaucoma
  > v = uveitis
  NB: long term untreated uveitis can -> glaucoma
• Gonioscopy (visualise iridiocorneal angle. NB: a closed iridiocorneal angle does not necessarily correlate with glaucoma)

Question 15

What order should an ophthalmic exam be carried out in?

Answer 15

1. distant observation for vision, obvious lesions
2. distance obs for symmetry
3. STT
4. Light examination (transillumination/slit test of anterior segment; distant and close direct to differentiate nuclear sclerosis v cataract and look at pillory shape/symetry; indirect observation of the fundus)

Question 16

Which type of visualisation has greater magnification and which has greatest field of view?

Answer 16

• direct close observation = greatest magnification

- indirect observation = greatest field of view, no magnification