Refractive surgery Flashcards
What radiation is typical excimer laser?
193nm, ultraviolet region
Why is an excimer laser suitable for refractive surgery?
Highly accurate
Highly repeatable
Minimal thermal effect and damage to surrounding tissue.
How does femtosecond laser work?
It separates corneal tissue through photodisruption.
It creates bubbles that tear the tissue.
Ultrashort bursts of radiation 10 to the-15 seconds inn duration.
What is energy density called?
Fluence mj/cm
What benefits do phakic implants have over LASIK?
The induce less coma and spherical aberration.
Reversible
What depth A/C do you need with:
ICLs
Artisan/aftiflex?
ICLs >2.8 for myopia, 3.0mm for hyperopia
Artisan > 2.7mm
Which phakic lens types causes most disruption to the endothelium?
Anterior chamber lenses
What minimum endothelial cell density iii required.
> 3500 at 21
2800 at 31
2200 at 41
2000 at 45
What percentage of patients are within 0.5D and 1D with artiflex lenses? How many see better than 6/12?
75%
94%
97% better than 6/12
What percentage of patients are within 0.5D and 1D with ICLs and how many achieve 6/12or better?
82%
97%
100%
What is intracor?
Femtosecond cuts within cornea, in non-dominant eye. Causes central cornea to steepen.
Are multifocal ablations unilateral or bilateral.
Best bilaterally
How can you judge the visual axis to aling corneal inlays?
Use 1st Purkinje reflex
What depth is Kamra inserted?
200um
What does the presyblens do?
steepens central cornea to induce a central near add.
How does the flexivue microlens work?
Increases overall refractive index causing a central near add.
What are the disadvantages of monovision?
Reduced binocular v/a
Reduced stereopsis
Reduced contrast sensitivity.
How do the rings on a diffractive lens alter with increasing add?
More rings
If someone reads the whole time, how would you insert multifocal IOLs?
Near add in non-dominant
If someone needs to use the computer the whole time how would you insert a multifocal?
Intermediate add in dominant eye
What post-op astigmatism should be aimed for with multifocal IOLs?
less than 0.75DC
How can astigmatism be managed in mIOL patients?
if <1.5DC use clear corneal incision opposite site
Limbal relaxing incisions
Bioptics (i.e. lens surgery + laser)
Toric mIOL
What features are there in a piggybank lens to prevent pigment dispersion syndrome and lens touch?
10 degree concavity of arms meaning lens sits closer to lens away from iris.
Posterior concavity prevents IOL touch
