What is the process of LASIK (Laser-Assisted In Situ Keratomileusis) and why is there post-operative pain?

LASIK Process and Post-Operative Pain

The LASIK Procedure

LASIK involves creating a hinged corneal flap (consisting of epithelium, Bowman layer, and superficial stroma), reflecting it, reshaping the exposed stromal bed with an excimer laser, and repositioning the flap—a process that preserves the central corneal epithelium, which is the primary reason LASIK causes significantly less pain than surface ablation procedures. 1

Step-by-Step Surgical Process

• Flap Creation: Either a mechanical microkeratome or femtosecond laser creates a hinged flap approximately 160 micrometers thick with a 300-degree circumference, leaving a portion of tissue attached to create a corneal hinge 2, 1

• Laser Ablation: The flap is manually reflected, exposing the stromal bed where the excimer laser reshapes the cornea to correct refractive error 1

• Flap Repositioning: The flap is replaced without sutures, allowing for rapid anatomical healing 2

• Anesthesia: The procedure is performed under topical anesthesia only in an outpatient setting 2, 3

Why Post-Operative Pain Occurs (and Why It's Minimal)

Mild to moderate discomfort can be expected during the first postoperative day after LASIK, but pain is significantly less than with PRK because the central corneal epithelium remains intact. 1

Pain Mechanisms in LASIK

• Corneal Nerve Disruption: The flap creation cuts corneal nerves, leading to decreased corneal sensitivity and potential corneal neuralgia in some patients 1, 4

• Inflammatory Response: Mild interface inflammation can occur, though severe diffuse lamellar keratitis (DLK) is uncommon 1

• Dry Eye Development: LASIK commonly causes or exacerbates dry eye symptoms due to nerve disruption affecting tear production, which can cause discomfort and eye strain 1, 4

Why LASIK Pain Is Less Than PRK

• Epithelial Preservation: The main advantage of LASIK over PRK is maintaining the central corneal epithelium, which dramatically increases comfort during the early post-operative period 5

• Reduced Wound Healing Response: Keeping the epithelium intact reduces the wound healing response that causes significant pain in surface ablation procedures 5

• Rapid Recovery: The procedure is described as "painless" with rapid functional recovery 2, 6

Common Post-Operative Symptoms (Not True Pain)

• Visual Aberrations: Glare, halos, and starburst effects (especially at night) can cause eye strain and secondary headaches through sustained accommodation effort 1, 4

• Dry Eye Symptoms: Development or exacerbation of dry eye is common and can persist for months to years, causing discomfort rather than acute pain 1, 7

Pain Management Approach

• Topical Antibiotics and Corticosteroids: Administered postoperatively for a short time 1

• Lubrication: Typically used in the postoperative period to address dry eye symptoms 1

• Protective Eye Shield: Recommended for short-term use 1

• Oral Analgesics: Variable use among practitioners based on surgeon preference 1

• Judicious Topical Anesthetics: Short-term use of dilute topical anesthetics can help control postoperative pain, though prolonged use should be avoided as it delays corneal epithelialization 1, 3

Red Flags Indicating Complications (Not Normal Post-Op Discomfort)

• Severe Pain with Redness and Photophobia: Suggests microbial keratitis rather than normal post-operative discomfort 1

• Persistent or Worsening Pain: May indicate DLK, central toxic keratopathy, or corneal neuralgia requiring specialized treatment 1, 4