Assessing Ocular Health

Question 1

when can blepharitis most likely have a bacterial cause?

Answer 1

If there is discharge

Question 2

if you need to dilate a patient, when do you do van herrik?

Answer 2

before you dilate them

Question 3

what is the order of checking eyes on a slit lamp?

Answer 3

1. external structures and adnexa
2. lids and lashes
3. conjunctiva (palpebral and bulbar)
4. sclera
5. lumbus
6. cornea
7. tears
8. anterior chamber
9. iris and pupil
10. lens
11. anterior vitreous
12. retina

Question 4

for diffuse illumination:
beam width?
angle?
mag?
observation?

Answer 4

-wide
-o
-x10
- diffuse filter so lids and lashes, general overview

Question 5

for parallelepiped,
beam width?
angle?
mag?
observation?

Answer 5

-2mm like thick optical section
-45
-x10
-depth and size

Question 6

for optic section,
beam width?
angle?
mag?
observation?

Answer 6

very thin and bright
-45
-x10
-depth like lens opacity and foreign body

Question 7

for specular reflection
beam width?
angle?
mag?
observation?

Answer 7

2-3mm parallelepiped
-30-45 for lens 45-60 for tear film
-x16
-anterior lens, corneal endothelium, precorneal tear film

Question 7

for indirect illumination
beam width?
angle?
mag?
observation?

Answer 7

• 1-2mm parallelepiped
  -45
  x10
  -fine blood vesseles, microcysts, areas that become bleached with excess light

Question 8

for conical beam
beam width?
angle?
mag?
observation?

Answer 8

-1mmx1mm dot
-45
-x16
anterior chamber cells and flare

Question 8

for sclerotic scatter
beam width?
angle?
mag?
observation?

Answer 8

-2-3mm parallelepiped
-45-60 decoupled
-x10
-corneal abnormalities, glowing ring of light around cornea seen when healthy

Question 9

for retro illumination:
beam width?
angle?
mag?
observation?

Answer 9

-fairly wide
-varies because it requires decoupling
-start on x16
-you can see microcysts, infiltrates, debris on corneal epithelium, vacuoles of anterior lens, crystalline lens opacities, CL deposits and neovascularisation

Question 10

for iris transillumination,
beam width?
mag?
observation?

Answer 10

-beam aperture should match the pupil size or be smaller than the pupil to avoid iris reflections
-10-16x
-to detect iris problems as a red reflex

Question 11

give some iris problems that iris transillumination technique can be used to detect

Answer 11

• Pigment dispersion syndrome (PDS)
• Pseudoexfoliation syndrome (PXF)
• Acute angle-closure glaucoma
• Fuch’s uveitis syndrome
• Herpetic iridocyclitis
• Trauma

Question 12

what is Shaeffer’s sign?

Answer 12

he presence of
a collection of brown pigmented cells in the anterior
vitreous following a PVD.

Question 13

explain what to do if your patient presents with shaeffer’s sign

Answer 13

refer them for urgent vitreoretinal assessment as this usually indicates posterior vitreous detachment (PVD) and/or retinal detachment (RD)

Question 14

from a digital photography photograph, how do you tell which eye is which?

Answer 14

if the optic nerve in the picture is on the right side then it is the RE and if its on the left side then it is the LE

Question 15

what are the positives of direct opthalmoscopy?

Answer 15

• Portable, hand-held
• Image real, upright, erect
• High magnification 15x for emmetrope
• Can assess for media opacities (cataract)
• Assessment of spontaneous venous pulsation
• Dilation not required
• Less expensive
• Easy to use

Question 16

what are the positives of VOLK?

Answer 16

• Binocular technique (provides stereoscopic view)
• Image is real, aerial, reversed, and inverted
• Variety of lenses allow for different magnifications
  and fields of view
• Slit lamp allows a range of magnification
• Dilation not always required
• Less affected by media opacities compared to
  direct ophthalmoscopy
• Less affected by ametropia

Question 17

what are the negatives of direct opthalmoscopu?

Answer 17

• Narrow field of view (less than 2DD)
• Close working distance
• No stereopsis
• Image affected by refractive error

Question 18

what are the negatives of VOLK?

Answer 18

• Bulk equipment
• Expensive
• Needs patient cooperation
• Not suitable for all patients (e.g., patients with
  mobility issues, children)

Question 19

what are the positives of fundus photography?

Answer 19

• Allows immediate viewing of the image
• Offers a larger retinal field of view (up to ~50°)
• Can be used with and without dilation of the patient
• Can be used in testing room to explain finding to patients
• Allows storage of photos and comparison from previous visits
• Different filters and dyes available to allow for different types
  tests
• Quick and simple technique to master

Question 20

what are the negatives of fundus photography?

Answer 20

• Image produced in two dimensional, unlike 3D in indirect binocular biomicroscopy
• The presence of cataract (reduced clarity)
• Not portable
• High cost
• Not suitable for all patients (e.g., patients with back/neck issues, not for all children)
• Needs patient cooperation

Question 21

what are the positives of Optomap?

Answer 21

• Non-invasive
• Images take less than a second
• Dilation not required
• Simultaneous view of the central pole, mid-
  periphery and periphery
• Less affected by pupil size, media opacities,
  aberrations

Question 22

what are the negatives of Optomap?

Answer 22

• No stereoscopic view
• Needs patient cooperation (aligning the
  patient)
• Do not get true colour image of the
  retina

Question 23

what are the positives of OCT?

Answer 23

• Non – invasive technique
• Instant imaging of the eye
• High repeatability
• Can get quantifiable measurements e.g., retinal thickness.
  Able to document small lesions of the retina and choroid
• Can be used to monitor/predict patient’s conditions

Question 24

what are the negatives of OCT?

Answer 24

The presence of cataract can interfere with the imaging
* Patient cooperation required
* Needs training to succeed the acquisition of optimal images