Coupon Accepted Successfully!


Refractive Surgeries



  1. Radial keratotomy
    1. It is not done now a days
    2. Procedure involves giving deep radial corneal stromal incisions in the periphery. This weakens
    3. the paracentral and peripheral cornea (causing bulging) and hence central cornea is flattened
    4. Low and moderate degrees of myopia (upto 5 D) achieve the best results
    5. Stability of refraction is lower compared to other refractive procedures
    6. Shorter incision-Mini-radial keratotomv indicates promising stability outcome
  1. Poor healing
    Irregular astigmatism
    1. KC
    2. Comeal opauties
    3. Post RK
  2. Irregular astigmatism
    Hence due to these complications, the procedure has been abandoned.
  1. Photo-refractive keratectomy (PRK)
    1. The procedure involves, removal of corneal epithelium and use of excimer laser (193 nm) to re profile the anterior curvature of the cornea which changes its refractive power. (by changing its radius of curvature)
    2. Treatment zone is 6.0 mm to 6.5 mm, this is large so as to avoid halos and edge glare
    3. It can correct myopia, hyperopia and astigmatism.
    4. Results are best for low to moderate myopia
  2. Laser-in-situ-kera tomileusis (LASIK)
    1. Procedure
    2. Pre - requisites of LASIK
      1. Age more than 18 years               
      2. Refractive stability. 
    3. Preoperative Evaluation
      1. Refraction
      2. Ultrasonic Pachymetry-It is done to evaluate the central corneal thickness to assess the safe limits of corneal stroma removal with laser ablation
        At least 200 micron of stromal bed should be left to prevent corneal ectasia.
      3. Detailed slit-lamp examination, retinal evaluation, eye dominance testing and measuring of IOP
    4. Absolute contraindications of LASIK*
      1. Keratoconus and other ectatic conditions          
    5. Relative contraindications of LASIK*
      1. Recurrent erosion syndromes           
      2. Large pupillary size             
      3. Small palpebral fissure.
    6. Complications*:
      1. Decentered ablation leading to irregular astigmatism (due to improper centered laser beam or poor    homogeneity).
      2. Central island formation*: It is a small steep area in the central cornea formed due to fluid accumulation   or delayed clearance of debris. It generally regresses over time.
      3. Irregular flap, displaced / dislodged flap.
      4. Dry eye - It is the commonest postoperative complication.
      5. DLK-Diffuse lamellar keratitis also known as "Sand of Sahara Syndrome"*.
      6. Interface contamination.
      7. Epithelial ingrowth.
      8. Interface infection.
  3. C-LASIK
    1. Also called Customized-LASIK
    2. C-LASIK or Zyoptix is the new generation of excimer laser used for the treatment of refractive disorders. This technique takes into account the patient's:
      1. Subjective refraction
      2. Ocular optical aberrations (these are higher order aberrations called "WAVE FRONT* ,­ ABERRATIONS" broadly described as "Aberropia"*).
      3. Corneal topography to design a personalized treatment based on total structure of the eye.
    3. Improving the optics of eye by removing aberration increases the contrast and spatial detail of retinal image
    4. Hence this technique is superior to LASIK.
  4. Lasek or epi-lasik
    1. It stands for Laser Sub-Epithelial Keratomileusis
    2. The procedure involves raising of a superficial epithelial flap with dilute chemical and use of excimer laser to re profile the anterior curvature of cornea. After this, the flap is draped back on the modified stromal surface.
  5. Intra-Corneal Lens Implant
    1. Also called Synthetic Keratophakia
    2. Intra corneal lenses are synthetic lenses placed in corneal stroma.
    3. It can be used to correct myopia, hyperopia, aphakia, and presbyopia.
    4. Two types of lenses are:
      1. Polysulfone
      2. Hydrogel.
      3. Polysulfone Lenses: It produces its effect due to high index of refraction. But due to its impermeability it has resulted in significant problems hence not under trial now.
      4. Hydrogel Lens: Hydrogel is a material of high water content that is permeable to corneal nutrients. Hydrogel has an index of refraction similar to that of cornea and therefore achieves its effect by transmittal of its curvature to the anterior surface of the cornea.
      5. In presbyopia, a small positive lens is inserted in the center of the cornea to create a multi focal effect.
  6. Phakic Intra Ocular Lens Implantation
    It's advantage over clear lens extraction is-preservation of patient's accommodative ability.
    1. Lenses may be implanted:
      1. In anterior chamber-Kelman Multiplex lenses
      2. Worst-Fechner iris--claw lenses.
      3. Posterior chamber plate haptic lenses-It is placed between crystalline lens and iris → ICL (implantable contact lens).
  7. Clear-Lens Extraction (CLE)
    The main disadvantage of this procedure for correction of high myopia is the risk of surgically induced retinal detachment (RD).

Test Your Skills Now!
Take a Quiz now
Reviewer Name