Week 1 - RGP I&R and Recording Flashcards
How should the patient be prepared?
• Describe the sensation
• Manage patient expectations
• Demonstrate practitioner confidence
To promote adaptation:
• Avoid local anaesthetics - up for debate
• Have patient close eyes and look down during adaptation
How must the RGP lens be prepared?
• Lens will arrive dry
• Inspect the lens before insertion. Look for any damage.
• Can focimeter the lens
• Lens must then be cleaned
- Cleaner - approx. 20 seconds in palm of hand
- Rinse (lots of rinsing)
- Conditioner - just before insertion
- Or MPS just like for soft lenses
- Double check the bottles!
How is an RGP Inserted?
• Lid control just as with soft lenses
• Give px a target to look at in distance
• Place lens on pointy/third finger
• Place lens straight onto cornea
• Gently release the lids
• Discomfort comes from top lid interacting with lens edge, so advising the Px to look down or hold their top lid up can help with adaptation
What happens when the lens is in the wrong direction?
• In the patient moves during insertion the lens can end up on the sclera
• This will be relatively comfortable for the patient
• Have the patient look in the opposite direction from the lens
• Use the lids to manipulate the lens towards the cornea
• If this does not work you can remove the lens from this location and start again
What is the adaptation time for a RGP lens?
• If no anaesthetic used there will be some reflex tearing, therefore initial assessment possible after 5-10minutes when stopped
• If the patient reports continued discomfort:
- Lift top lid up, should relieve discomfort
- If it doesn’t, remove lens and check lens/ocular surface, as may be FB or cleaner not rinsed off
- The fit may be too loose and cause mechanical trauma
How is an RGP lens removed?
• Have Px look straight ahead
• Lift top lid above the middle of the lens, and bottom lid below middle of bottom of lens
• Gently but firmly apply pressure to edge of lens with lids and lens should pop out
• If lens not centred, the lens will slide around ocular surface
• Lid margins need to be against ocular surface, if roll the lids out and see palpebral - there wont be enough tension to pop lens out
What are the slit lamp techniques used to assess RGP CL fitting?
- White light
• Centration
• Coverage
• Movement - Fluorescein
• Central
• Mid-peripheral
• Peripheral
How do we assess the centration using SL?
• Lens position after the blink (lid attachment vs. intrapalpebral)
• Lens centration after the blink (central, temporal, nasal, inferior, superior)
• Lens centration in the interblink period
• Some decentration is acceptable as long as the pupil remains covered by the optic zone
How do we assess the coverage using SL?
• The lens should be centred to the cornea in the primary position of gaze and should not cross limbus on excursion of gaze and upgaze
• Should be noted as ‘no crossing of limbus in all positions of gaze’ or ‘ crosses limbus inferiorly on upgaze’ etc.
• Should not cross the pupil margin in any direction of gaze.
N.B. assessed with white light but photos easier to show you with fluorescein.
How do we expect the RGP lens to move?
• Lens movement of the lens after the blink
• Ideally by 1-2mm
• Can retract the lids to look for movement with gravity
• A well-fitted lens should drop gently over the apex of the cornea,
• a flat-fitting lens will slide around the apex with a more rapid movement, can be a “swan dive” type movement
• a tight lens will move much more slowly and remain over the apex rather that drop towards the lower limbus, can “rock” side to side as it does move
How is the Diameter assessed?
• Look at the lens compared to the cornea
• What is the size of the gap between the edge of the limbus and the lens?
• Should be approx 1mm all around
• If we think about a standard corneal diameter of 11mm and a lens about 9mm
How is Fluorescein instilled for an RGP fitting?
• Wet the fluoret with saline and shake excess off
• Tap onto the conj with flat part of strip
• No edges/no swiping
• Too little/much can affect assessment of fit
• A couple of taps should be sufficient
Fluorescein pattern analysis (sphere)?
• The brighter the glow, the thicker the tear film
• Dark regions indicate minimal tear-film thickness
• Fluorescence visible if tear lens has minimum thickness of about 10-20um
• “Pooling” means that the tear lens is quite thick
Which 3 areas should he looked at? (sphere)
• Look at 3 areas (with the lids retracted and lens centred if necessary)
• Centre
• Mid-periphery
• Periphery
What is the Fluorescein pattern analysis? (toric)
• The brighter the glow, the thicker the tear film
• Dark regions indicate minimal tear-film thickness
• Classic “dumbbell” pattern when a spherical lens is fitted on a significantly toric cornea; can vary depending on the fit and amount of astigmatism.
