Soft CL fit Flashcards
How do you assess CLs suitability in patients?
General Observation - hygiene, palpebral aperture, ability to comply with cleaning of lenses/ insert or remove.
Motivation
POHx (prev CL, DED, amblyopia, inj, inf, ect)
GH (meds, DM, pregnancy, smoking)
Age and gender (older F ? tear film quality, kids ? parents able to assist)
Occupation
Environmental factors (e.g. dust)
Refractive error
What are the soft CL pre-fit measurements?
HVID
Pupil diameter
Palpebral aperture
lid position
Corneal curvature + regularity
Subjective Rx
Slit lamp exam - anterior eye (anything that contraindicates wear?)
At what subjective Rx must you adjust for BVD?
> +/- 4.00DS
what is the equation to work out effective BVP?
F = F/(1=dxF)
Give an example of how to instruct a patient while inserting a soft CL
Have the patient look up, while keeping their head straight
Hold the patient’s upper lid
Place the lens on the inferior conjunctiva
Have the patient look down (towards the lens)
Release the lids and have the patient blink gently
How do you assess a soft CL fit?
Comfort
coverage
centration
movement
tightness - push up and pull down test
How do you define ideal, slight or excessive coverage and centration of a lens?
ideal - no decentration on blink, can have minimal movement vertically
slight - horizontal or oblique decentration of the lens with blin but limbus is not encroached
excessive - moves so much that limbus becomes exposed/ encroached on blink
How do you assess movement?
In primary gaze, also look for lag on version movement (generally looking up for this centration can change between 0.3mm-0.7mm and be a good fit)
Reduce beam size to estimate lens movement
How do you grade lens movement?
- Excessive – (unacceptable) > 1mm movement; limbal exposure on blink
- Loose - (acceptable) 0.5 to 1mm movement; no limbal exposure on blink
- Ideal- 0.2 to 0.5mm movement; lens edge does not encroach limbus
- Tight – (acceptable) 0.1 to 0.2mm movement; minimal movement on blink; conjunctival
vessels straddling the lens edge are unaffected - Too tight - (unacceptable) no movement observed; conjunctival vessels straddling the lens edge are distorted
How do you grade tightness with a push up test?
o 85-100% (Too Tight) — lens difficult to dislodge or doesn’t return to original position
o 65-80% (Tight) — slowly returns to the original position
o 45- 60% (Ideal) — the lens is easy to dislodge, returns to position quickly
o 25-40% (Loose) — lens moves instantly with pressure, returns with temporal or nasal recovery (slides over the limbus)
o 0-20% (Too Loose) — lens is too loose and easily dislodged, or moves up with the lower lid alone on blinking
How do you grade movement with a pull down test?
o Tight fit: no movement on pull down test
o Good fit: gentle movement but no displacement
o Loose fit: Lens is displaced but recentres instantly without apparent discomfort
o Acceptably loose fit: lens is displaced and recentres with apparent discomfort
o Unacceptably loose fit: lens is displaced and does not recentre
What needs to be completed during a CL AC visit?
**make sure patients wear their lenses to an AC appt
History - wear time, CL handling, pt perception of comfort and vision
VA with Cls
Over refraction - include binocular balance
Assess fit and condition of lenses
observe pt removing lenses
Assess anterior eye w slit lamp
Discuss future AC follow ups
What constitutes patient tuition on soft CLs?
- insertion and removal of lenses
-inform patient on lens adaptation,
-signs and symptoms of complications
-associated risks
-care regime for their lenses
what are the steps to assess a soft contact lens during a fitting?
insert lens
check for symptoms of vision and comfort
assess fit on slit lamp (centration, coverage, movement, edge alignment, push up test, if toric lens rotation)
if not appropriate try another lens
if lens fits well then complete VA and over-refraction with lens in eye.
