Complications of Refractive Surgery

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.

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.
• 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_._