PC - Slitlamp Biomicroscopy 2 - Week 4 Flashcards
Describe specular reflection, and 4 structures it is used to examine.
Angle of incidence equals the angle of observation.
Used to view the corneal endothelium, lens capsule, TF, and surfaces.
Can specular reflection be used to see any surface, or only specific ones?
Any surface
What three structures specifically is specular reflection used to examine?
Tear film quality
Corneal endothelium
Anterior lens surface
How does the anterior lens surface appear?
Orange peel
What corneal condition can be seen using specular reflection, what syndrome is it associated with, and what causes this appearance?
Corneal guttata, visualised using specular reflection.
It is associated with Fuch’s dystrophy, and appears as dark spots on the corneal endothelium.
Desribe how sclerotic scatter is carried out, where the focus should be, and where the light source should be aimed.
What does this setup result in?
Angle at 60, the cornea should be in focus centrally, but the light source should be offset so it focusses on the limbus.
Results in total internal reflection, and a halo of light is seen around the entire limbus.
What 3 things can be seen using sclerotic scattel?
Any area of abnormality including:
Scars
Oedema (stromal)
Particles/FB
Name the four grades of the Van Herrick technique, the ratio, the degree it corresponds to, the angle it indicates, and whether closure is likely.
Grade IV - 1:1, VH>=1, angle 35-45, open angle, closure impossible.
Grade III - 1:2, VH=0.5, angle 20-35, open angle, closure unlikely.
Grade II - 1:4, VH=0.25, angle 10-20, narrow angle, closure possible.
Grade I - <1:4, VH<0.25, angle ~10, narrow angle, closure likely
Describe the shadow test and the four grades.
Light placed obliquely to the eye and the shadow across the iris is observed.
Grade IV - open, good spread of light across the entire iris, proximal crescent shadow.
Grade III - open, partial shadow of the distal iris.
Grade II - likely narrow, increased eclipse of distal iris.
Grade I - very narrow, large eclipse of the distal iris.
Describe Smith’s test, its formula and what it measures.
Beam at 60 degrees, horizontally aligned.
Find the corneal and lens mires.
Increase the beam length until the two mires touch.
Depth = 1.4 x height
Measures AC depth
What AC depth should be treated with caution, and what length should be expected?
Caution with <2.1 height reading
Length should be >1.5mm
Describe the modified Smith test, and how it is carried out.
Describe what angles correspond to narrow and open angles.
What does every 5 degrees correspond to in mm?
Used when a SL beam height isnt calibrated.
Beam is focussed and 2mm in height.
Illumination angle isnt fixed, but altered until corneal and lens mires touch.
If they touch at 60 degrees, AC depth is 2.5mm
<60 degrees is well open.
>60 degrees is narrow
Every 5 degrees is 0.25mm
What 6 uses does fluorescein staining have?
- Checking integrity of the corneal and conjunctival epithelium
- TBUT
- Enhances detection of bumps, abrasions, and defects
- RGP fittings
- Goldmann tonometry
- Seidel’s sign
What is fluorescein?
NaFI
Describe the recording for a slit-lamp examination (15).
Draw each eye, R+L Examine the following, with a tick if inspected: Lashes Lids Conjunctiva Papillae sup. and inf. Palpebrae Cornea Iris Lens AC (quiet/noisy) VH - grade \_\_ Iris shadow \_\_ ACD Smiths or Modified Smiths \_\_ degrees, \_\_mm TF (quality) TBUT \_\_ secs Write OU for each category when both eyes are inspected.
