Refractive Sx pre-op

Question 1

Why do we look for refractive stability +/-0.50?

Answer 1

Look for undiagnosed keratoconus

Patient satisfaction

Question 2

Is diabetes a contraindication to Rx surgery?

Answer 2

No.

Question 3

How long must you leave RGPs out for prior to surgery?

Answer 3

at least 3 weeks or a week for every decade they have worn them

Question 4

How long must soft lenses be out for?

Answer 4

at least 1 week

Question 5

Is pupil size still important?

Answer 5

With femto-second flaps and larger ablations probably not.

Question 6

What mesopic size pupil should be treated cautiously?

Answer 6

7mm

Question 7

Total RMS of 0.4 with a 6mm pupil could indicate what?

Answer 7

undiagnosed keratoconus

crystalline lens changes

Question 8

What sorts of pachymetry are there?

Answer 8

Ultrasound
Anterior segment OCT
Schiempflug imaging
Scanning slit on orbscan

Question 9

What LASIK corneal stromal bed should you aim for?

Answer 9

250 microns

Question 10

What post-lasek corneal thickness should you aim for?

Answer 10

350 microns

Question 11

Which causes less dry eye, femto-second or manual keratome or LASEK

Answer 11

LASEK (least)
Femto (more superficial cut)
Microkeratome (worst)

Question 12

What steepness of cornea should you avoid to prevent dry eye?

Answer 12

Shouldn’t be steeper than 48/9D

Question 13

Azar looked at schirmer without anaesthesia pre-op - what did he find?

Answer 13

If pre-op greater than 20mm then normal tear film (TBUT> 10secs) at 9 months
If pre-op greater than 10mm then no significant dry eye symptoms albeit some