Complications of Refractive Surgery

Complications of Refractive Surgery

Complications of Refractive Surgery

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Early Complications - Flap Fiascos

  • Free Cap: Flap completely detached. Risk ↑ with flat corneas. Manage by replacing and suturing if needed.
  • Buttonhole: Central perforation of flap. Risk ↑ with steep corneas, poor suction. Abort procedure.
  • Irregular Flap: Uneven flap thickness or edge. Caused by blade issues or eye movement.
  • Thin/Thick Flap: Deviations from target thickness. Affects refractive outcome.
  • Decentered Flap: Flap not centered on pupil. Can cause irregular astigmatism.
  • Flap Striae: Wrinkles in the flap.
    • Microstriae: Fine, usually resolve.
    • Macrostriae: Visually significant, may need refloating/stretching.
  • Epithelial Ingrowth: Epithelial cells under flap. Peripheral, self-limiting or progressive (needs lifting & scraping).
  • Diffuse Lamellar Keratitis (DLK): "Sands of Sahara". Non-infectious interface inflammation. 📌 "Sands of Sahara" appearance.
    • Grade 1: Mild, peripheral.
    • Grade 2: Dense, central.
    • Grade 3: Clumping, stromal melt risk.
    • Grade 4: Stromal melt.
    • Treat with topical/systemic steroids.

Diffuse Lamellar Keratitis (DLK), also known as "Sands of Sahara," is a sterile inflammatory reaction at the flap interface, typically occurring 24-48 hours post-LASIK. Early, aggressive steroid treatment is crucial.

Corneal Healing & Optics - Vision Villains

  • Corneal Haze:
    • Patho: Myofibroblast activity, abnormal collagen. Commoner post-PRK.
    • Risk: ↑Ablation depth, UV exposure.
    • Rx: Topical steroids, Mitomycin C (MMC).
  • Corneal Ectasia:
    • Patho: Progressive corneal thinning & biomechanical weakening → steepening, irregular astigmatism.
    • Risk: Thin pre-op cornea (<500 µm), Residual Stromal Bed (RSB) <250-300 µm, high myopia, abnormal topography (e.g., FFKC).
    • 📌 RSB < 300 µm: Ectasia Risk!
    • Rx: CXL, Intacs, Keratoplasty.
    • ⭐ > Post-LASIK ectasia risk significantly increases if the residual stromal bed (RSB) is less than 250-300 µm.
  • Refractive Surprises:
    • Under/Overcorrection: Nomogram issues, healing response.
    • Irregular Astigmatism: Decentered ablation, small optical zone, uneven healing.
    • Rx: Glasses/contacts, enhancement.
  • Visual Quality Issues:
    • Glare, halos, starbursts, ↓contrast.
    • Causes: Large pupils, HOAs (spherical aberration), small/decentered optical zone.
    • Rx: Brimonidine, wavefront-guided ablation.
  • Epithelial Ingrowth (LASIK):
    • Epithelial cells under flap margin.
    • Risk: Flap re-lifts, poor adhesion, epithelial defects.
    • Rx: Observation; flap lift & scrape if significant/progressive.

Post-LASIK Ectasia Topography and Pachymetry

Inflammation & Late Issues - Pathogen Parade

  • Diffuse Lamellar Keratitis (DLK) 📌 "Sands of Sahara"
    • Sterile, non-infectious interface inflammation; "sands" appearance.
    • Stages: 1 (peripheral), 2 (central, granular), 3 (clumped, dense), 4 (stromal melt).
    • Rx: Intensive topical steroids (e.g., Prednisolone acetate $1%$ q1h); interface irrigation for Stage 3/4.
  • Infections (Pathogen Parade):
    • Early onset (<72 hrs): Bacterial (Staph aureus, Strep pneumoniae). Gram +ve cocci common.
    • Late onset (>72 hrs): Fungal (Candida, Aspergillus), Atypical Mycobacteria (M. chelonae), HSV reactivation.
    • Signs: Infiltrate, AC reaction, hypopyon.
    • Rx: Corneal scraping/culture, fortified antibiotics, antifungals. Corneal infiltrate post-LASIK
  • Other Late Issues:
    • Dry Eye Syndrome: Very common. Rx: Lubricants, punctal plugs.
    • Epithelial Ingrowth: Cells under flap. Grade 1 (minimal), 2 (advancing), 3 (visually significant/flap melt). Rx: Flap lift & scrape for Grade 3 or symptomatic.
    • Corneal Ectasia: Progressive thinning & steepening. Risk: thin pre-op CCT (<500µm), high myopia, abnormal topography.
    • Flap Striae: Microstriae (common) vs. Macrostriae (visual disturbance, needs refloat/stretch).

⭐ Infectious keratitis after LASIK is a sight-threatening emergency; Pseudomonas aeruginosa can cause rapid corneal melt within 24-48 hours.

High-Yield Points - ⚡ Biggest Takeaways

  • Dry eye syndrome is the most common complication after refractive surgery.
  • LASIK flap issues: Striae, dislocation, epithelial ingrowth, and Diffuse Lamellar Keratitis (DLK).
  • Post-LASIK ectasia, a severe corneal thinning, is a major concern; screen for keratoconus.
  • Infectious keratitis: Rare but sight-threatening, requiring prompt treatment.
  • Corneal haze after PRK/surface ablations is reduced by Mitomycin C.
  • Glare, halos, starbursts: Common night vision issues, usually improve over time.
  • Steroid-induced glaucoma: Risk from post-operative steroid drops, monitor IOP_._

Practice Questions: Complications of Refractive Surgery

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Flashcards: Complications of Refractive Surgery

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Hyperopic photorefractive keratotomy is used for treatment of _____

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Hyperopic photorefractive keratotomy is used for treatment of _____

hypermetropia (hypermetropia/myopia)

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