Lecture 11: Refractive surgery Flashcards
What are the complications of radial keratotomy?
Glare from incisions
Reduced contrastsensitivity
Diurnal variation
Hyperopic drift
Weakened globe
Whar are the limitations of photorefractive keratectomy (PRK)?
-Early lasers - technical constraints
-Small diameter ablation zones
Single pass treatments = aberration
-Poor beam homogeneity
-Edge profile sub-optimal
-Individual wound healing variation
-Haloes
What are the complications of PRK?
Regression
Anterior stromal haze
Aberrations - halos
Night vision problems
Loss of BCVA
Loss of contrast sensitivity
What are the advantages of LASIK?
Virtually no haze or scarring
Rapid recovery
More accurate / predictable
Extended range (-10 to +5D ?)
Virtually (!) painless
Both eyes treated at same time
Re-treatment is relatively easy
When is LASIK used as an NHS treatment?
Myopia after cataract surgery
Treating corneal graft astigmatism
Severe disability :
Motoneurone disease
Parkinson’s disease
Stroke patients - CVA
Friedreich’s ataxia
How can you reduce complications of LASIK?
pre-operative:
patient selection / suitability
patient counselling
realistic expectations
refractive aims (eg monovision)
per-operative:
poor preparation
sterility issues
equipment-related
technique-related
What flap complications can you get?
Partial flap (obstruction / suction break)
Buttonholes + thin flaps (steep corneas)
Macerated flap
Free flap (cap – flat corneas, low IOP)
No flap! (loss of suction)
Flap slippage / dislodged flaps
Epithelial defects
How can you avoid flap complications?
Drapes, good exposure, vacuum
good centration, copious irrigation
Chayet sponge
mask hinge (eg Buratto guard)
How can you avoid flap complications?
Drapes, good exposure, vacuum
good centration, copious irrigation
Chayet sponge
mask hinge (eg Buratto guard)
What are the post-operative complications of LASIK?
-flap macro- and micro-striae- can get striae
-macrostriae due to slippage
microstriae due to settling
-debris
-displaced flaps
-corneal surface problems
-dry eye syndrome
-DLK – diffuse lamellar keratitis
-infective keratitis
-epithelial ingrowth
What is the treatment of flap striae?
If BCVA reduced or quality of vision
impaired, consider lifting flap and
repositioning.
Smooth out striae
Hypotonic saline to hydrate
Suturing / PTK (last resorts!)
What are the symptoms of epithelial ingrowth?
What is the treatment?
FB sensation
optical problems
keratolysis-melting
How can you manage dry eye syndrome?
pre-op screening / exclusion
tear film supplements (pres. free)
punctum plugs
sodium hyaluronate
cyclosporin A
autologous serum
What refractive complications can you get of LASIK?
under- and over-correction
induced cylinder
irregular astigmatism
halo / glare / ghosting / scatter
What are the signs of diffuse lamellar keratitis?
white granular cells in peripheral infilitrate
