Infections After Refractive Surgery

Infectious keratitis (IK) is a rare but serious complication of refractive surgery, with a reported prevalence of 0.0004%. Post-laser-assisted in-situ keratomileusis (LASIK) IK has declined, particularly with femtosecond lasers, which reduce epithelial defects and improve wound healing. The average onset of IK is reported to be 22.9 ± 38.7 days. Early-onset infections (within 1 week) are typically caused by Gram-positive bacteria, while delayed-onset infections (2–3 weeks post surgery) are often due to atypical Mycobacterium, fungi, or Acanthamoeba. Post-photorefractive keratectomy (PRK) IK, associated with larger epithelial defects, is frequently caused by Staphylococcus aureus and Streptococcus pneumoniae. Post-small incision lenticule extraction (SMILE) IK, though rare, has the shortest onset time (2.2 days) and is linked to Streptococcus pneumoniae and Aspergillus. Clinical features vary by causative organism. Common symptoms include pain, blurred vision, photophobia, redness, and irritation. Slit-lamp examination reveals corneal infiltrates, which may be solitary or multiple. Early-onset infections typically present with white, round infiltrates, suggestive of Gram-positive bacteria or Pseudomonas. Late-onset infections may show yellow, dense infiltrates with irregular margins (fungi) or grayish, linear, or ring-shaped infiltrates (Acanthamoeba, mycobacteria, or Nocardia). Risk factors include ocular comorbidities (e.g., blepharitis, dry eye), systemic conditions (e.g., diabetes, HIV), and intraoperative contamination. Early lifting of the corneal flap (in LASIK) or aggressive topical therapy (in PRK/SMILE) improves outcomes. Studies show 55.5% of IK cases are cured with medical treatment alone, while 16.7% require keratoplasty. Visual outcomes vary, with 36.1% of post-PRK and 28.2% of post-LASIK patients achieving 20/20 vision or better. Despite advancements, IK remains a challenging complication, emphasizing the need for early diagnosis, targeted treatment, and ongoing vigilance across all refractive procedures.