This document discusses various refractive surgery procedures aimed at correcting refractive errors such as myopia, hyperopia, and astigmatism by altering the cornea and/or crystalline lens. It describes procedures such as radial keratotomy, photorefractive keratectomy (PRK), laser-in-situ keratomileusis (LASIK), and phakic intraocular lens implantation. It provides details on how each procedure is performed and discusses complications that can occur. The document compares PRK and LASIK, noting that while LASIK recovery is quicker, it carries greater surgical risk due to creation of a corneal flap. Both procedures have around a 0.2-0.3% risk of losing more than
3. INTRODUCTION
• A RANGE OF PROCEDURES
AIMED AT CHANGING
REFRACTION OF THE EYE BY
ALTERING THE CORNEA AND / OR
CRYSTALLINE LENS
• REFRACTIVE ERRORS
CORRECTED INCLUDE MYOPIA,
HYPERMETROPIA AND
ASTIGMATISM
4.
5. CORRECTION OF MYOPIA
• CORNEAL SURGERY
– RADIAL KERATOTOMY
• RADIAL INCISIONS IN PERIPHERAL CORNEA
– PHOTOREFRACTIVE KERATECTOMY
– LASER-IN-SITU KERATOMILEUSIS
(LASIK)
– INTRASTROMAL PLASTIC RINGS
• CAUSE CENTRAL CORNEAL FLATTENING
9. CORRECTION OF HYPERMETROPIA
• CORNEAL SURGERY
– PRK
• CAN CORRECT LOW DEGREES OF
HYPERMETROPIA
– LASIK
• CAN CORRECT UPTO 4 D
– LASER THERMAL KERATOPLASTY
• HOLMIUM LASER
• LENS SURGERY
– PHAKIC INTRAOCULAR LENS
IMPLANTATION AT AN EARLY STAGE
10. CORRECTION OF
ASTIGMATISM
• CORNEAL SURGERY
– ARCUATE KERATOTOMY
• MAY BE COMBINED WITH COMPRESSION
SUTURE PLACED IN PERPENDICULAR MERIDIAN
– PRK
• CAN CORRECT UPTO 3 D
– LASIK
• CAN CORRECT UPTO 5 D
• LENS SURGERY
– USING A TORIC INTRAOCULAR LENS
IMPLANT
– POSTOPERATIVE ROTATION OF IMPLANT
11. PHOTOREFRACTIVE
KERATECTOMY
• PERFORMED WITH EXCIMER LASER
• MYOPIA TREATED WITH ABLATING
THE CENTRAL ANTERIOR CORNEAL
SURFACE
• 10 MICROMETER ABLATION
CORRECTS
1 D OF MYOPIA
• CAN CORRECT
– MYOPIA UPTO 6 D
13. TECHNIQUE OF PRK
• VISUAL AXIS MARKED
• PATIENT FIXATES AT AIMING
BEAM OF THE LASER
• LASER APPLIED TO ABLATE
ONLY BOWMAN LAYER AND
ANTERIOR STROMA
• TAKES USUALLY 30 – 60
SECONDS
17. Excimer Laser Epithelial
Keratomileusis(LASEK)
Corneal epithelium is loosened and set aside, or
removed, refractive procedure is performed with
the excimer laser (PRK), Finally epithelial layer is
brought back to recover the cornea again and held
in place
Indications
Myopia up to – 6.0 diopters
Hypermetropia up to + 3.0 diopters
Astigmatism up to 3.0 diopters
Advantage
Less glare problem than PRK
18. LASER IN-SITU
KERATOMILEUSIS
• CURRENTLY MOST FREQUENTLY
PERFORMED REFRACTIVE PROCEDURE
• CAN CORRECT
–
–
–
HYPERMETROPIA OF UPTO 4 D
ASTIGMATISM UPTO 5 D
MYOPIA OF UPTO 12 D
• TO PREVENT CORNEAL ECTASIA, A
RESIDUAL CORNEAL BASE OF 250
MICROMETER THICKNESS MUST REMAIN
AFTER THE FLAP HAS BEEN CUT AND
TISSUE ABLATED