Ocular CL Examination

Question 1

Explain how better correction of vision can be achieved with RGP lenses

Answer 1

eye tissues (retinal) stretch leading to retinal disease/detachment
Myopia control CLs can treat myopic maculopathy in kids

Question 2

Explain control of myopic refractive error with contact lenses

Answer 2

eye tissues (retinal)

Question 3

Describe 5 uses for ‘bandage’ CLs

Answer 3

recurrent epithelial erosions
painful bullous keratopathy (damaged corneal endothelium causes corneal oedema)
post-trauma
post-intra-ocular surgery
post-refractive surgery

Question 4

How can CLs be used for drug delivery with an example

Answer 4

Oedema (corneal endothelium can’t maintain hydration/transparency so swells)
Microcysts (irregular epithelial cell growth)
Neovascularisation (BV in normally avascular cornea)

Question 5

How can CLs be used for clinical diagnosis?

Answer 5

Triggerfish lenses take indirect IOP measurements via an embedded strain gauge for continuous glaucoma monitoring

Question 6

Describe the differences between keratometry/topography

Answer 6

Keratometry represents 3mm diameter annulus
Topographer provides more info

Question 7

Describe 4 ocular surface redness responses

Answer 7

Metabolic changes (hypoxia)
Toxic reaction (solutions)
Inflammatory responses
Mechanical influences

Question 9

Explain 3 direct O2 related responses

Answer 9

Oedema (corneal endothelium can’t maintain hydration/transparency so swells)
Microcysts (irregular epithelial cell growth)
Neovascularisation (BV in normally avascular iris)

Question 10

Describe 6 background statistical concepts for Efron Clinical Grading Scales

Answer 10

Sensitivity - systems ability to detect change in severity of condition (fine is better than course)
Concordance - grading of frequency of perfect agreement at different times
Precision - difference in grading between multiple clinicians
Accuracy - difference between subjective grading/true grading
Reliability - standard deviation of frequency distribution from multiple grades over time
Consistency - range within which grading estimates cannot be considered different for a given grading system

Question 11

Describe the layers of the tear film

Answer 11

Outermost Lipid layer produced by meibomian glands (lids) reduces tear evaporation, maintains TF stability/smooth surface for vision
Middle Aqueous layer produced by lacrimal gland provides hydration/nourishment cleaning debris (irritants) and maintaining healthy corneal surface to prevent infection
Inner Mucous layer produced by goblet cells (conjunctiva/cornea) adheres TF to ocular surface preventing friction during blinking and contributes to anti-microbial defence, prevents tears draining too quickly

Question 12

Why is conjuctival staining checked before fitting and explain tarsal conjunctivitis

Answer 12

check interaction between lens edge/conjunctival tissue
tarsal conj. due to interaction of palpebral tarsal conjunctiva with from CL surface