1. CORNEAL
REFRACTIVE
SURGERY

2. Corneal Physiology
 Transparent, dome shaped, outermost layer that covers the front of the eye.
 Provides greatest amount refractive power to the eye.
 Avascular, relies on atmosphere for oxygen and aqueous humor for its
nutritional needs.
 Corneal surface is kept smooth by
constant moistening action of tears.

3. Layers of Cornea
Epithelium (55µm).
 It evenly distributes the nutrients to other layers.
 It maintains stromal dehydration.
Stroma (470µm)
 Collagen fibers arrangement are responsible
for corneal strength, optical characters.
Endothelium (5µm).
 It stretches to cover the dead cells,
which reduces the cell density and impact
on fluid regulation.
 It pumps the excess fluid from stroma.

4. Shape of Cornea
 Slightly oval
 Horizontal & vertical dimensions are 11mm & 12 mm app.
 Pupil diameter ranges from 2mm to 6mm, which reduces optical zone of
cornea to its central 6mm.
 Peripheral cornea is thicker than central cornea.

5. Pachymetry
 It is the process of measuring the thickness of the cornea.
 Corneal Pachymetry is essential prior to a LASIK procedure for ensuring
sufficient corneal thickness to prevent abnormal bulging of the cornea, a
side effect known as ectasia.
 Ultrasonic & Optical pachymetry.
 It also helps in finding the development of glaucoma when combined with
standard measurement of IOP .
 Corneal thickness is 560 microns.

6. Corneal Topography
 It is a process of mapping the surface curvature of the cornea.
 It is to produce a detailed description of the shape and power of
the cornea because shape determines the visual ability.

7. Refractive Laser Surgery

8. LASIK
Advantages:
 Pain free recovery.
 Quick restoration of eyesight.
 Better result for severe
short sight.
Disadvantages:
 Dry eyes.
 Halos, starburst.
 Loss of contrast sensitivity.
 Thick corneal flap (100-180 microns).

9. Femto LASIK

10. Photorefractive Keratectomy
Used to correct mild to moderate
 Myopia.
 Hyperopia.
 Astigmatism.
Advantages:
 Highly accurate for myopia.
 80% patients have 20/20 vision
Disadvantages:
 Mild discomfort including minor
eye irritation.
 Dry eyes.

11. LASEK
Advantages:
 No flap complications.
 Causes less dry eyes than
LASIK.
 Finer trephine blade is used
instead of microkeratome.
 Good for patient with
thin cornea.
Disadvantages:
 May cause more pain and
discomfort than LASIK.
 Dry eyes.
 Longer recovery time than
LASIK.

12. Epi-Lasik
Advantages:
 Less complications to corneal nerves.
Disadvantages:
 Dry eyes.
 Poor night vision.

13. Intrastromal Corneal Implants
Used to treat
 Myopia.
 Keratoconus.
 It has two semicircular rings made of PMMA.
Advantages:
 Easily removable.
 Small incision.
Disadvantages:
 Vision disorder.
 Problem with night vision.

14. Thank You
Prepared by
Ghose Mohamed
Medicals International
Riyadh
KSA