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Therapeutics > Refractive Surgery > Flashcards

Refractive Surgery Flashcards

1
Q

Advise for patient prior to consult for eligibility for refractive surgery?

A
  1. Discontinue CL use – 3 weeks for hard CL and 3 days for soft CL
  2. Refractive stability over the last year (<0.5D change)
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2
Q

Work up to assess eligibility for refractive surgery

A
  1. Vision → Distance, near, aided, and unaided
  2. Refraction →subjective and cycloplegic
  3. Slit lamp Biomicroscopy →fluorescein staining when indicated.
  4. IOP
  5. Pupil measurement →esp. in scotopic conditions
  6. Keratometry
  7. Corneal pachymetry (CRITICAL)
  8. Corneal topography → identify any forme fruste, early keratoconus or irregular astigmatism.
  9. Dilated fundus examination →exclude retinal disease (limited visual prognosis)
  10. Schimers → check for aqueous defiency
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3
Q

Advise to give px follow refractive surgery eligibiyt consult

A

Consent: discuss all risk and benefits and potential alternatives
* Expected refractive outcomes and residual refractive error.
* Limitations due to presbyopia
* Monovision (pros and cons)
* Changes in vision (myopes losing near vision)
* Post surgical care.

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4
Q

Contraindications for refractive surgery

A
  • Unstable refractive
  • Thin cornea
  • Corneal abnormalities
  • Significant cataracts
  • Uncontrolled glaucoma
  • Uncontrolled autoimmune disorders
  • Unrealistic patient expectations
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5
Q
A
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6
Q

What is RK?

A

radial – like corneal incisions (85% of corneal depth) around the optical zone → causing corneal flattening. 4 or 8 incisions and can correct up to 6D of myopia (works best on 1 – 4 D). Tangential smaller cuts are used to correct astigmatism.

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7
Q

Cons of RK

A
  • Hard to predict final rx (final rx range of 4.42D)
  • Glare and halo side effects post op due to changes corneal topography.
  • Increased dry eye post op.
  • Contraindicated for CL post due to risk of NVC.
  • Make cataract surgery more complicated later on
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8
Q

READ PRK laser steps

A

READ PRK laser steps

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9
Q

Correction range for PRK

A

Corrective range -12D to +5D, astigmatism up to 6D. Better result on lower rx

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10
Q

Cons for PRK laser

A

High rx = high risk of regression

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11
Q

patients that my benefit from PRK

A
  • Abnormal corneal topography / irregular astigmatism
  • Corneal disease (e.g. RCES and epithelial basement membrane disease or scars)
  • Thinner corneas
  • Dry eye disease of Glaucoma patients
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12
Q

Management follow PRK

A
  1. Bandage CL and topical NSAIDs until re – epithelised. NSAIDs may slow healing.
  2. Topical antibiotics: fluoroquinolone 4 – 5x daily for 5 -7 days or until re – epithelised.
  3. Topical anaesthetic every 30 mins for first 24 hours as required.
  4. Chilled PF artificial tears
  5. Topical steroids (e.g.,) to help avoid refractive regression and post operative corneal haze.
    a. prednisolone acetate QID for 1 week then taper.
    b. Fluorometholone – 5 x a day for 1 week then taper.
  6. Manage expectations: vision is blurred until cornea is healed.
  7. Day 1 post op: ensure bandage CL is in place.
  8. Day 5 -7 post op: remove CL once re-epithelisation is complete.
    a. Ensure IOP is well controlled, and inflammation is reducing.
  9. 1 month post op: corneal topography to ensure ablation is in place.
  10. Review regularly.
    a. Return sooner if RCES, photophobia or pain.
    b. Retreatment can occur 6 months later.
    c. Vision can change especially 4 years after op – regular eye test to check rx.
  11. Complications:
    a. Poor night vision, residual refractive error, decentred ablation zone, corneal haze, cornea ectasia
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13
Q

READ LASEK steps

A

READ LASEK steps

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14
Q

Pros of LASEK

A

Lower pain and corneal haze post op than PRK.

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15
Q

Cons of LASEK

A

No difference in healing, VA or rx compared to other techniques.

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16
Q

READ LASIK steps

A

READ LASIK steps

17
Q

Cons of LASIK

A
  • Increased risk of HSV reactivation
  • Increased post op high order aberrations
  • Contraindicated: risk of corneal ectasia or irregular corneal topography
18
Q

Pros of LASIK

A
  • More rapid restoration to vision
  • More predictive final rx outcome
  • Better quality of life after
19
Q

management for LASIK/LASEK

A

Management
1. Antibiotic QID for 1 week → prevent infection.
2. Topical steroid QID for 1 week then weekly wean (or NSAIDs)
3. PF lubricating eyedrops: avoid eye rubbing and contact sport, consider appropriate protection.
4. Day 1 post op:
a. May has mild discomfort, dryness.
b. VA should be 6/6 or better.
c. Check for corneal changes (i.e. wrinkles, epithelial ingrowth, oedema, haze)
d. Contact surgeon if there any abnormalities.
5. 1 month post op: refraction - should be stable.
a. LASIK is repeatable.
6. Complications
a. Flap complications: risk factors – highly steep/flat corneas, deep set eyes, head movement or lid squeezing.
b. Diffuse lamellar keratitis → sterile infiltrates at stromal interface. Treat with topical steroids hourly to 2 hourly (consider oral steroids in steroids)
c. Epithelial ingrowth → usually self-limiting. May require surgical discussion. Infectious keratitis (SIGHT THREATENING) – microbial sampling to confirm diagnosis. Intensive antibiotic therapy promptly + topical steroids. Consider flap irrigation!

20
Q

Read SMILE steps

A

Read SMILE steps

21
Q

SMILE pros

A

Correct up -10D, astigmatism up to 5D.
* 95% of px will have +/-1.00D post op rx.
* Good refractive stability – regression <0.1D
* Expected VA: 6/6 better.
* Less higher order aberrations induced.
* Better corneal sensitivity and TBUT than LASIK

22
Q

SMILE cons

A
  • Px with stromal scars - increased risk of inadvertent perforation of anterior stromal cap during surgery
  • Poor outcome in px with >2.50 DC
  • Day 1 vision not as clear as LASIK
23
Q

Complication from SMILE (refractive surgery)

A
  • Epithelial defect, minor tear, bleeding, cap perforation, microdistortion at bowman’s membrane, trace haze, keratitis
24
Q

SMILE enhancements?

A
  1. Repeat SMILE at a different corneal plane.
  2. Surface ablation
  3. Converse SMILE cap to LASIK flap
25
Q

What are cornea inlays?

A

Implant in the anterior stroma to correct presbyopia. Increases curvature. Using similar principle to pinhole

26
Q

pros of corneal inlays

A
  • Good vision at a distance
  • Can be extracted if required.
  • May be performed in combination with cataract surgery.
  • No disruption to future examination or imaging
27
Q

Cons of corneal inlays

A
  • Glare / halo / NV symptoms.
  • Contrast sensitivity loss.
  • Small pupil: may limit distance vision.
  • Corneal haze
  • If combined with LASIK: longer recovery.
28
Q

procedure for corneal inlays

A

Procedure (performed on non-dominant):
1. Femtosecond laser used to create stromal flaps/pocket.
2. Implant placed under flap onto the stromal bed.
3. Antibiotic drops QID for 1 weeks + steroid drops: minimise wound healing, haze formation, opacification and avoid refractive shift.

29
Q

Corneal inlay complications

A
  1. Lens decentration, epithelial ingrowth, dry eyes, corneal melting / vascularisation / opacification, unrealistic patient expectations.
30
Q

keratoconus facts

A

Keratoconus – thinning of the corneal stroma:
* Usually bilateral (severity may be asymmetrical)
* Associated with sleep apnoea, down syndrome, floppy eyelid syndrome.
* Onset: teens to early 50s
* Presentation: central/paracentral stromal thinning with inferior apical protrusion causing progressive irregular astigmatism → abnormal topography

31
Q

keratoconus management

A
  1. Correct astigmatism: Hard RGP CL or scleral CL
  2. Consider corneal cross linking.
  3. Penetrating keratoplasty
  4. Deep anterior keratoplasty
32
Q

What is fleishers ring?

A

Pigmented rings resulted from iron deposition in basal epithelial cells.

33
Q

What is vogts striae

A
  • Vertical lines in the posterior stroma of Desment’s membrane
  • Caused by undulation of the continuous collagen lamellae of the stroma.
  • Can also be found in healthy eyes.
34
Q

Lens base refractive surgery eligibiltiy?

A
  1. Stable Refraction (cycloplegic) – a high degree of ametropia, or dislike glasses / CL use
  2. 21 years or older
  3. Comprehensive ocular exam – pupil <5 -6 mm
  4. back vertex distance
  5. Corneal topography, CCT, endothelial cell count >2500 cell /mm2 or >2000 cells /mm¬¬2 in px over 40
  6. Biometry (AL, ACD, corneal diameter) – AC angle 30 degree or more
  7. IOP
35
Q

Expectation of lens based refractive surgery?

A
  • Better VA and refractive predictability than LASIK and PRK
  • High patient satisfaction
  • Less risk of corneal ectasia and retinal detachment
  • Available for hyperopes
36
Q

management for lens based refractive surgery

A
  1. Topical antibiotics
  2. Topical steroids/NSAIDs for 4 weeks
  3. Measure IOP immediately post op
  4. Day 1 post op: VA, IOP, check would and vault of lens
  5. 1 week post op: VA, IOP, vault of lens
  6. Review 1, 3, 6 , 12 months post op
37
Q

Possible complications for lens based refractive surgery

A

Complication: Cataracts, ocular hypotension, risk of inflammation, infection and bleeding, risk of pupillary block and angle scarring. Endothelial cell damage may lead to corneal decompensation.

Therapeutics (10 decks)

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