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127 Cards in this Set
- Front
- Back
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Radial incisions (4-8, 16, or 32) in the cornea with a scalpel to reduce its curvature describes what procedure?
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Radial Keratotomy (RK)
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RK involves the reduction of the ___ height.
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sag
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What does AK stand for? What is involved?
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Astigmatic Keratotomy. Same technique as RK, but to fix astigmatism.
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Your patient said she had AK done a few years ago - you see horizontal incisions at the 6:00 and 12:00 positions. Was this a WTR or ATR cornea?
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WTR
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What are the problems with AK and RK?
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- Less predictability (K depth)
- Decr K integrity - Visual probs (over/underRx, irreg astig, small OZ - glare & halos) - Limbal involvement (corneal neo) |
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T/F - Excimer lasers involve lots of heat therefore require constant irrigation to cool off the cornea.
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False - it is a "cool" laser
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T/F - Ablation involves evaporation.
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False - ablation involves breaking of bonds
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What does ASA stand for? What it is also known as?
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Advanced Surface Ablation, aka PRK (Photorefractive Keratectomy)
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How does ASA work?
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Alcohol is used to loosen the epithelium, then an excimer laser is used to remove the epithelium.
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What is the refractive error limit of ASA?
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Myopia up to -7.00
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(Review pros and cons of each surgery type)
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Just a reminder
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T/F - ASA is ok for thin corneas.
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True
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How long does the epithelium take to heal after ASA?
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1-2 weeks
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What is the biggest and most frequent complication of ASA?
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Stromal haze
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Which has a higher risk of infection and inflammation - ASA or LASIK?
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ASA
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Which procedure involves the patient on steroids longer - ASA or LASIK?
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ASA
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What is Mitomycin-C used for in ASA?
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Decreases occurrence of post-op corneal haze.
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What does LASEK stand for?
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Laser Epithelial Keratomileusis
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Describe the LASEK procedure.
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Alcohol soln is used to loosen the epithelium, then the epith is lifted back, the excimer laser sculpts the cornea, then a bandage CL is used until the epith heals (~1 wk).
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Describe Epi-LASIK
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Same as LASEK but instead of alcohol soln, a blunt oscillating blade is used to create the corneal flap.
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In order, which has the longest to shortest recovery in ASA, LASIK, and LASEK/Epi-LASIK?
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Longest to shortest recovery: ASA, LASEK/Epi-LASIK, LASIK
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List in order of worst to best patient comfort: ASA, LASIK, LASEK/Epi-LASIK.
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Wost to best: ASA, LASEK/Epi-LASIK, LASIK
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Describe the LASIK procedure.
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A microkeratome slices a flap of corneal tissue, which is folded back and an excimer laser reshapes the tissue.
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What types of refractive error can LASIK be used for?
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Myopia, hyperopia, and astigmatism; hyperopia not as recommended as myopia.
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How soon is vision functional in LASIK? How about full vision recovery?
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24 hrs for functional vision, 1 week for full recovery.
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What is IntraLase?
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A bladeless technique that uses an infrared light beam to cut tissue (photodisruption); the laser forms microscopic bubbles of CO2 and water vapor - the bubbles interconnect to create a dissection plane. Basically a way to make the flap w/o a blade.
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What are the advantages of IntraLase?
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- More ctrl w/ flap thickness & size; less flap thickness variability
- Can control hinge location - K surface and flap edge are smoother - Precise and predictable - Less complications from blade (slippage, contamination, debris) |
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What does CK stand for?
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Conductive Keratoplasty
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What procedure was mentioned in the slides that is FDA approved for correcting presbyopia?
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Conductive Keratoplasty (CK)
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How does CK work?
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Uses radio frequency energy to shrink areas of peripheral corneal collagen (due to its electrical resistance causing heat buildup); applied at points in a circular pattern, causing steepening of the cornea.
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What refractive error range is CK approved for?
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+0.75 to +3.00 D with up to +0.75 D astig.
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T/F - CK takes a long time for recovery.
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False - immediate recovery
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T/F - CK has good patient comfort, besides FB sensation.
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True
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T/F - CK requires AB and steroids for a long period after Tx.
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False - short term ABs and steroids
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T/F - CK requires re-treatment.
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True - lasts only 3-5 yrs
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T/F - CK involves corneal leukomas (scarring).
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True
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T/F - CK involves a large optic zone in higher Rx's.
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False - a SMALL optic zone
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What are INTACS? How does the procedure go?
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Intracorneal Rings Segments; two channels made in peripheral cornea by intralase or manual dissector, and small curved PMMA segments inserted into these tunnels.
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What are INTACTS used for?
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Tx K thinning disorders e.g. keratoconus, PMD & Post-LASIK ectasia. Attempts to flatten and center the KC cone - arc shortening effect, and helps with rigid lens centration. Basically enables pt to fit RGPs.
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What is the max K-value indicated for INTACS?
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57D
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T/F - INTACS help halt/reverse progression of keratoconus.
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False
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T/F - INTACS does not require additional visual correction.
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False
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What does CLE stand for?
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Clear Lens Extraction
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How does CLE work?
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Internal lens of eye is removed (as in cataract extraction) and a lens implant of another power is inserted.
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When is CLE indicated?
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Pts over 40 w/ hyperopia (high myopia?)
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What does PIOL stand for?
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Phakic Intra-Ocular Lens
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How does PIOL work?
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The crystalline lens is still there, but an IOL is placed in front of or behind the iris; basically an internal CL.
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What types of refractive error can PIOL correct?
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Hyperopia, myopia, and low astig.
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What does CE stand for?
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Cataract extraction
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What is custom LASIK?
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An aberrometer measures the amount of higher order aberrations (HOAs) and uses these measurements with the laser to correct the HOAs.
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Compare wavefront guided vs wavefront optimized ablation.
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Guided = Tx refract error and pre-op HOAs; removes 22 um/D
Optimized = Tx refract error while preventing induction of post-op HOAs; for pts w/ min or no pre-op HOAs; removes 16 um/D (Conventional LASIK = 12 um/D) |
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What is active eye tracking?
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Maintains alignment of laser with eye movement
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What is iris registration?
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Helps account for cyclorotation of the eye (since eye is cyclorotated when lying down)
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What are the power ranges of LASIK and ASA (according to pg 10)?
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-11.00 sph and 6.00 cyl
+6.00 sph and 6.00 cyl Depends highly on K thickness |
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Higher Rx corrections are indicated with which procedures?
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Clear lens extraction and phakic IOLs.
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What is the typical treatment zone in conventional LASIK?
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6 mm
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How much K thickness is removed per diopter in conventional LASIK?
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1 D = 12 um
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What is the ideal flap thickness?
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125 um (intralase = 90 um)
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What is the ideal corneal bed thickness?
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250 um
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What is the ideal residual corneal thickness?
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125 um (flap thickness) + 250 um (corneal bed thickness) = 375 um
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Larger Tx zones and custom ablations will remove (less/more) tissue.
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more
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Your patient has a CCT of 475 um. His Rx is -6.00 OD, -8.50 OS. Can this pt get LASIK?
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OD: 6D x 12 = 72
72 + 375 = 447, OD is OK (447<475) OS: 8.5 x 12 = 102 102 + 375 = 477, OS not ok (477>475) |
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Your patient who is interested in LASIK has a 0.50 D increase in minus in his right eye. Should you wait it out or is it ok to proceed with LASIK?
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Wait for stability if you see a 0.50 D or greater change.
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T/F - Diabetes is an absolute CI to refractive surgery.
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False - a relative CI
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T/F - Dry eyes is an absolute CI to refractive surgery.
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True if severe
False if mild (a relative CI) |
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T/F - Irregular topography is a relative CI to refractive surgery.
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True - wait for stability
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T/F - Previous corneal surgery is an absolute CI to refractive surgery.
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False
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How soon should you wait for refractive surgery after pregnancy? Nursing?
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6 mo after birth or
3 mo after nursing |
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How long do SCL wearers must be weaned off their lenses prior to refractive surgery? RGP wearers?
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SCL = 2-4 wks or until refraction is stable
RGP = 4-20 wks or until refraction is stable |
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T/F - It is not appropriate to make recommendations for ophthalmologists.
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True - we DO NOT make recommendations!
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What is considered "stable"?
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2-3 repeatable refractions and topography, 2-3 wks apart
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T/F - ABs are indicated the day before surgery.
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True - Zymar/Vigamox QID
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How soon do you return to the surgical site after surgery?
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The next day for f/u
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Outline the routine post-op schedule.
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1 day, 1 wk, 2 wks (optional), 1 mo, 3 mos, 6 mos; after this, yearly exams and DFE are highly recommended
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What are common post-LASIK problems after 1 day?
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Dislodged flap, macro/micro-striae, dry eyes (severe w/ diffuse SPK), surgical debris
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What are common post-LASIK problems after 1 week?
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DLK, epithelial ingrowth, under/overRx, glare/halos, dry eyes
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What are common post-LASIK problems after 1 month or more?
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Regression, dry eye
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When is GAT ok to do after the surgery?
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One week after.
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If VAs are worse than 20/40 on day 1, what should you do next?
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Follow more closely
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What kind of meds should be taken post-op? Dosage/length?
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ABs and steroids qid x 1 wk, ATs q2h
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How long can you not rub your eyes after surgery?
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1 month
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How long can you not swim/get water in your eyes after surgery?
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1 week
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When can you start using eye makeup again after surgery?
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1 week
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T/F - No heavy lifting >25 lbs within one month of surgery.
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False - one week
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T/F - No running or any rigorous physical activity within one week after surgery.
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False - 3-4 days
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T/F - A dislodged flap after will resolve itself.
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False - should be sent back to MD right away; encourage pt to keep eyes closed, NO proparacaine or cycloplegics.
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How do you Tx macro-striae?
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If no visual disturbances, can be left alone. If decr BCVA, then flap must be refloated and smoothed.
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What Sx is involved w/ macro-striae?
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Irreg astig, glare/halos, decr BCVA.
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What Sx is involved w/ micro-striae?
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Usually no Sx
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What is the biggest complication post-LASIK?
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Dry eyes
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T/F - Dry eyes can cause the pt's pre-op Rx to come back.
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True - this is regression
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T/F - If surgical debris is not affecting vision or healing, you can leave them alone.
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True - otherwise, flap is lifted and interface is cleaned
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Why is it important to carefully monitor IOPs in the post-op follow-ups?
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Pt has been taking steroids.
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What is DLK?
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Diffuse Lamellar Keratitis - granular material in the interface causing inflammation; results in progressively decreased VAs
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How does DLK appear with staining?
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1+ = inferior SPK
2+ = diffuse SPK 3+ = coalesced SPK 4+ = "sands of sahara" |
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How do you Tx DLK 1+?
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Can resolve w/o Tx, but can also increase steroid gtt regimen (Pred Forte 1% q2h)
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T/F - DLK 2+ does not involve a decrease in BCVA.
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False - BCVA decreases slightly and also involves a mild hyperopic shift
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How do you Tx DLK 2+?
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Pred Forte 1% :
- q1h x 1d - q2h x 1d - q3h x 1d - ABs qid x 1wk Follow pt daily; if no improvement then refer to surgeon (float flap and clean) |
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T/F - DLK 3+ involves a further drop in BCVA and more (-)
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False - more (+)
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How do you Tx DLK 3+?
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Immediate surgical intervention - float flap, irrigate, Tx w/ steroids
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How does DLK 4+ present?
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Dense corneal haze; end stage, cornea melting or scarring (no AC rxn or hypopyon); BCVA 20/60 or worse (hyperopic irregular astig).
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How do you Tx DLK 4+?
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Immediate surgical intervention - float flap, irrigate, Tx w/ steroids (same as DLK 3+)
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What is epithelial ingrowth?
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Presence of epithelial cells in the lamellar surface post-LASIK usually within 1 wk to 3 mos; white to gray speckles, lines, strands, sheets.
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What are the three methods of how epithelium is introduced to the interface (epithelial ingrowth)?
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1) Growth of solid sheet of peripheral epith beneath flap
2) Implantation in the interface during surgery 3) LASIK over pre-existing excisional corneal surgery |
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How soon do you see epithelial ingrowth?*
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Can't detect until at least 1 week from surgery
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T/F - Epithelial ingrowth is due to poor flap adhesion or alignment.
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True
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What illumination is best for seeing epithelial ingrowth?
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Retroillumination
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T/F - Epithelial ingrowth is always aggressive.
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False - can be sedentary or aggresive
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T/F - Since the epithelium is growing over the flap in epithelial ingrowth, there is no staining.
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False - staining at the edge
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1+ epithelial ingrowth is within __mm of flap edge, while 2+ is greater than ___mm of the flap edge.
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2, 2
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T/F - 2+ epithelial ingrowth involves no demarcation line.
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True - this indicates progression
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How often should you follow up on a 2+ epithelial ingrowth?*
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q 1-2d
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T/F - 2+ epithelial ingrowth involves necrosis.
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False - 3+ involves necrosis
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T/F - 2+ epithelial ingrowth has no rolled edges, but 3+ has rolled edges.
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False - both 2+ and 3+ involves rolled edges (3+ has corneal melt and 2+ doesn't however)
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T/F - 3+ epithelial ingrowth is urgent and recurrences are common.*
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True - requires close f/u
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How do you Tx 3+ epithelial ingrowth?
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Lift the flap, scrape off epith cells, replace flap and place bandage CL; pt on ABs on steroids x1wk
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T/F - Higher likelihood of over/undercorrections with higher Rx.
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True
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T/F - over/undercorrections are usually found on the next day.*
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False - no enhancement done less than 8 wks after surgery
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Glare and halos are common within how long from the surgery?
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Common in first 3 mos
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What causes glare and halos in post-op?
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Caused by flap healing - fluid in interface ("edema"); vision improves as flap binds to cornea base
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T/F - Glare and halos can be caused by dry eyes, not only by flap healing.
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True
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What is normal UCVA at day 1 and beyond day 1?*
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Day 1 = 20/40 or better
Beyond = 20/25 or better |
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What is normal BCVA at day 1 and beyond day 1?*
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Day 1 = 20/25 or better
Beyond = 20/20 |
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How does a normal flap look like at day 1 and beyond day 1?*
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Day 1 = slight staining around edge possible
Beyond = intact & smooth |
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How does a normal epithelial surface look like post-op?*
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Clear and smooth
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How does a normal interface look like at day 1 and beyond day 1?*
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Day 1 = trace edema, debris possible, no granular WBCs
Beyond = clear |
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What is the extent of glare and halos post-op?*
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Day 1 to 2 mos = expect night Sx w/ improvement over time
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