Laser in situ keratomileusis (LASIK) is a refractive surgery technique that uses an excimer laser to reshape the cornea. A corneal flap is created and folded back, then the excimer laser removes tissue from the exposed stroma to reshape the cornea. LASIK can correct refractive errors up to -12 diopters of myopia, +4 diopters of hyperopia, and +5 diopters of astigmatism. A thorough examination including pachymetry and topography is required to ensure proper patient selection and avoid complications during and after the procedure.

1. Laser in situ
keratomileusis
LASIK
DR. ADEEL BAIG
RESIDENT AL-SHIFA TRUST EYE HOSPITAL

2. LASIK
Laser (or laser-assisted) in situ keratomileusis .
The excimer laser is used to reshape corneal stroma exposed by the creation of
a superficial flap; the flap remains attached by a hinge to facilitate accurate and
secure repositioning.

3. LASIK can generally be used to treat higher refractive errors :
◦ Hypermetropia up to 4 D,
◦ Astigmatism up to 5 D and
◦ Myopia up to 12 D

4. Myopia is corrected by central ablative flattening
Hypermetropia by ablation of the periphery so that the centre becomes steeper.

5. The first step to avoid complications after LASIK is proper patient selection

6. History
Age: above 18 years.
Refractive status: Stable for atleast 1 year.
H/O
oDry eyes , Keratoconus,
oRefractive surgery, keratoplasty, contact lens use

7. Examination
BCVA including Cycloplegic Refraction
Complete Slit lamp examination:
oRule out dry eyes, blephritis, pterygium, corneal scar, degenerations, limbic
vascularization, AC cells etc.
oIOP
oDilated Post segment exam.

8. Investigations
Pachymetry:
oFor central corneal thickness
oA residual corneal base at least 250 μm thick must remain after ablation.

9. Corneal Topography:
◦ Discontinue Contact lens use (Soft 2 weeks, RGP 3 weeks).
◦ To Rule out Keratoconus and other Ectasias
◦ K Readings: Post Op Limits 35D(Myopia)- 48D(Hyperopia)

10. Contraindications
Patients with collagen vascular disease
Patients with autoimmune or immunodeficiency diseases
Women who are pregnant or nursing
Patients with signs of keratoconus
 Patients taking isotretinoin or amiodarone

11. Relative contraindications
Fuchs’ corneal dystrophy
Strabismus
Ophthalmic herpes simplex or herpes zoster
Other systemic diseases likely to affect healing, such as diabetes and
atopic disease
Patients with abnormal corneal topographies or with ocular
abnormalities as well as systemic conditions
That are likely to affect wound healing.

12. Procedure
Lid Speculum
Draping
Topical Anesthesia

13. Step 1
• A suction ring centered on the cornea is applied to the globe; this raises the
intraocular pressure substantially.

14. Step 2
Once the eye is immobilized, the flap is created. This process is achieved with a
mechanical microkeratome using a metal blade, or a femtosecond laser that
creates a series of tiny closely arranged bubbles within the cornea.

15. Step 3
The corneal flap is folded back on the hinge exposing the middle portion of the
cornea.

16. Step 4
The excimer laser is then used to remove tissue and reshape the center of the
cornea.

17. Step 5:
The hinged flap is folded back into its original position.

19. Post Op care
Topical Antibiotics
Topical Steroids
Topical NSAIDS
Artificial Tears

20. Complications
Intraoperative:
o‘Buttonholing’ (penetration) of the flap,
oFlap amputation,
oIncomplete or irregular flap creation
oRarely penetration into the anterior chamber.

21. Complications
Postoperative:
oTear instability
oPersistent epithelial defects.

22. Wrinkling, distortion or dislocation of the flap.
Subepithelial haze with resultant glare, especially
at night.

23. Epithelial ingrowth under the flap
Diffuse lamellar keratitis (‘sands of the Sahara’)

24. Bacterial keratitis
Corneal Ectasia

25. THANK YOU