Refractive surgery - Dr. Sharma Flashcards
What are the types of refractive surgeries?
Incisional, Thermal procedures, Excimer laser refractive surgery, INTACTS (Intracorneal) and Intraocular Surgery
During Incisional surgeries, which cuts would flatten the corneal more?
Larger incisions, central incision, deeper cuts and shorter tunnel cuts
What are the types of incisional refractive surgeries?
Radial keratotomy (RK) Astigmatic Keratotomy (AK) Relaxing Incisions: Limbal (LRI) or Peripheral (PRI)
Radial Keratotomy was only used for _____ and _____ correction.
myopia, astigmatism
Where do the inrastromal corneal ring implant in the cornea?
deep stroma
How thick does the corneal has to be inorder to do intrastromal corneal ring implant?
450microns thick
INTACS Intrastromal corneal ring segment is to correct ______ and treat _______.
myopia. keratoconus
Laser Thermal Kertoplasty is used to treat _______, causes shrinkage ______ collagen.
hyperopia, stromal
In Conductive Keratoplasty, _____ waves heat/shrink collagen.
radio
What kind of gas laser is use in the excimer laser?
Argon-fluoride gas laser
Excimer laser is to correct _______ and _______.
refractive errors, higher order aberrations
Phtorefractive Kertectomy is mechanically removed ________ by using excimer laser photoablates ______ and ________.
corneal epithelium, bowman’s, anterior stroma
_________ may reduce risk haze development.
Mitomycin-C
What is used to loosen epithelium in Laser Subepithelial Keratectomy (LASEK)?
Alcohol
T/F LASEK is more discomfort than PRK.
False, less discomfort
LASIK uses a mechanical ______ or ______.
microkeratome (blade). Femtosecond laser/ INTRALASE (no blade)
Wavefront LASIK can take away ____ order aberration.
high
Larger diameter Flap and more ablation will cause ____ tissue loss per diopter and _____ glare.
more, less
Thicker corneas, Keloid formers and higher corrections > -6D is an indication for which refractive surgery?
LASIK
In LASIK complication, microK flap causes ____ microns, Femto lap _____ microns and Excimer _______ microns/diopter of corneal ectasia (fluids build up in corneal stroma).
160, 90-110, 14
What are some flap complications from LASIK surgery?
Button hole flap, epithelial ingrowth, striae, torn flap, “free” flap, lost flap, aborted flap, dry eye and diffuse lamellar keratitis (DLK).
The indication for having phakic intraocular lens is ____D hyperopia, ____D myopia and ____D astigmatism?
20, 20, 7.5
Is having a thin corneal or thick cornea an indication for phakic intraocular lens?
thin
T/F Phakic intraocular lenses is irreversible.
False. reversible
What are some general risks for phakic intraocular lenses?
- Endopthalmitis
- Risidual refractive error
- Glare
What is the name for the anterior chamber lens?
Verisyse
What is the name for the posterior chamber lens?
Visian
What is the minimum depth the anterior chamber needs to be inorder to do the Verisyse (anterior chamber lens)?
3.2mm
Anterior chamber lens can cause ___________ and posterior chamber lens can cause ___________.
a. cataract
b. glaucoma
glaucoma, cataract
What are some refractive surgery pre-op evaluations you have to do?
- Medical history
- Ocular history
- Contact lens history
- Refractive data (with and without cycloplegic), EOM, Pupil size, Keratometry and Pachymetry, Keratoconus Topographic Index (take avg diopter power of rings 2,3 and 4 from placido’s disc. more than or equals to 47.20D suggestive keratoconus) and I-S value
What is the Pentacam measure?
- Topography front/rear cornea limbus to limbus
- Pachymetry from limbus to limbus
- Anterior chamber angle volume and depth
- Densitometry crystalline lens
What kind of image is the Pentacam?
Scheimpflug images
What are some risk factors for dry eye?
Gender (female more than male), Age (>50), Race (Asian), Rx ( > -6, any +), Medicine, Cigarette smoking.
______ is the most common side-effect of LASER procedure.
dry eye
Before the LASIK surgery, what should you check on the patient’s eye?
make sure there’s no corneal staining, TBUT greater than 10secs, Stable refraction, stable aberrometry and no symptoms
What are the kind of dry eye evaluations you can perform on your patients before LASIK?
- Schirmer Test
- Phenol Red Test
- Tear Osmolarity
- Evaluation Tear Meniscus
What dyes can you use to check the corneal integraties before LASIK?
- Fluorescein staining to check corneal integrity for any ruptured epithelial surface. check TBUT as well.
- Lisamine Green stain devitalized cells. highlights dryness of bulbar conjunctiva
- Rose Bengal/Lisamine Green stain damaged cells and assess conjunctival surface disease
What are some risk factors of ectasia in LASIK surgery?
- abnormal topography
- residual stromal bed thickness
- Age
- Preoperative corneal thickness
- Refractive error
What does a bowtie topography tells us about the patient’s cornea?
keratoconus
What are some contraindications for LASIK?
- Under 18
- Pregnant or nursing
- Dx. w/collagen vascular disease, autoimmune or immunodeficiency disease
- Taking Accutane and/or Amiodarone
- Keratoconus
Why is taking Accutane contraindicate for LASIK?
it causes dry eye. it’s also an side effect of LASIK surgery
Why is take Amiodarone contraindicate for LASIK?
Amiodarone has many ocular side effects, which includes photosenisitivity, corneal microdeposits, hazy vision, glare and colored haloes around lights.
What diseases affect wound healing after LASIK?
Diabetes, Connective tissue and/or atopic disease, Immunocompromised status, history of herpes simplex/zoster, keratitis sicca and glaucoma
Why is glaucoma contraindication with LASIK?
LASIK thins the cornea and thin cornea can cause glaucoma.
What are the pre-op medications/treatments for LASIK?
Omega 3, Doxycycline (antibiotics), Restasis, artificial tear lubrication, Lid massage and punctal occlusion
In what findings during day one after LASIK your patient has to go back to the center?
- dislodged flap
- flap striae
- infection
Regression toward the pre-LASIK refractive state in ________ and _______ corrections and is correlated with _______.
higher myopic, hyperopic, dry eye
What are some indications for post LASIK ectasia.
- delayed acquired astigmatism
- loss of BCVA
- Elevation Topography
- Aberrometry - elevated vertical coma
What is the treatment for ectasia after LASIK?
- glasses
- contact lenses (soft toric, RGP, Hybrid)
Others: - Intra-corneal Ring Segment (INTACT)
- collagen Cross-linking
- Keratoplasty
T/F Microkeratome(blade lasik) losses more corneal sensation than PRK (mechanically scrape off cornea).
True
Patients with contrast sensitivity of 12 cycles/degree return to pre-surgical levels in _______.
3 months
Patients with contrast sensitivity of 18 cycles/degree return to pre-surgical levels in _______.
1 month