This document discusses various corneal laser surgeries and procedures. It describes corneal cross-linking, which uses UV light and riboflavin to increase corneal stiffness and halt keratoconus progression. It is less invasive than corneal transplantation. Intrastromal corneal rings are also discussed, which are implanted in the corneal stroma to decrease steepening and astigmatism in keratoconus. Refractive surgeries like PRK, LASIK, and SMILE are outlined that use lasers to reshape the cornea. Preoperative evaluation, cryotherapy, and potential complications of procedures are summarized as well.

1. Corneal Laser Surgery
Bayh Alfaidy

2. Keratoconus
Management
Eyeglasses/Soft contact lenses.
Rigid gas permeable (RGP) contact lenses.
Intracorneal rings.
Corneal cross-linking.
Corneal transplant.

3. Corneal Cross-
linking

4. Corneal Cross-linking
A relatively new treatment using ultraviolet A (UVA) with
photosensitizer riboflavin(vitamin B2) to rise corneal stiffness.
FDA approved to the corneal cross-linking system to treat
patients with progressive keratoconus and post-LASIK ectasia.
Glasses or contact lenses may
still be needed.
Not a treatment but prevents
progression of KC.

5. Corneal Cross-linking methods
epi-on epi-off
Less-invasive Invasive
The cornea's epithelial layer is left intact. The epithelium is removed to get a quicker, deeper
saturation of the riboflavin
Patients experience less pain Pain
recover faster recovery delayed

6. What is the best method epi-off or epi-on?
• There are some people who believe you get a better cross-linking
effect from “epi-off” why
• Because you have a higher concentration of riboflavin and the light can
reach deeper.

7. Treatment Procedure
Sterile conditions in the operating room.
Local anesthesia.
Remove central 7mm of the corneal epithelium.
Riboflavin 0.1% solution applied for 5 minutes.
After allowing riboflavin to permeate through the cornea for at least 5 minutes.
The UVA irradiation.

8. Procedure video

9. Study (1))Wollensak, Spoerl, & Seiler, 2003).
• A significant increase in corneal rigidity by approximately 70% in
untreated VS treated corneas. (porcine cornea)

10. Study (2)(Wollensak, Spoerl, & Seiler,
2003).
• Most studies report a greater
than 90% success rate in a
stabilization of keratoconus
progression after CXL
application.

11. Complications of Corneal Collagen Cross-Linking
• Postoperative Infection/Ulcer.
• Corneal Haze.
• Endothelial Damage.
• Treatment Failure (progression occur following treatment).

12. Intracorneal
rings

13. Intrastromal Corneal Rings
• Small rings made of synthetic material.
• Implanted within the corneal stroma.
• Implantation is a safe and reversible technique.
• The rings will decrease the corneal steepening and astigmatism
associated with keratoconus.

14. Intrastromal Corneal Rings
Definition Small rings made of synthetic material.
Implanted within the corneal stroma.
The rings will decrease the corneal steepening and
astigmatism associated with keratoconus.
Implantation is a safe and reversible technique.

15. Procedure
• The procedure does not involve corneal tissue nor does it invade the
central optical zone.
• Implanting the ring deep into the cornea, we need to perform
channels in the stroma where the segments will be inserted.
• The creation of channels deep into the cornea,, can be achieved
either by the mechanical technique or the use of femtosecond laser.

16. Procedure video

17. Complications
Intraoperative complications
• Incomplete tunnel creation
• Misdirection of ring segment
into stroma
• Perforation into anterior
chamber
• Broken body of rings
Postoperative complications
• Opacification
• Infective keratitis
• Segment migration
• glaucoma

18. Refractive
Surgery

19. Refractive Surgery
• There are two basic types of corrective refractive surgery:
1. Changes the curvature of the cornea.
2. Changes the internal optics of the eye (the natural lens of the eye).

20. Photorefractive keratectomy (PRK)
• In PRK, the epithelium is physically scraped away and an excimer laser
reshapes tissues situated under the epithelium.
• The epithelium layer grows back.
• PRK is an option for those with a thin cornea.
Disadvantages:
oLonger recovery days.
oMore discomfort through healing than with LASIK.

21. PRK Procedure video

22. Laser in situ keratomileusis (LASIK)
• The most general category of photorefractive surgery
the Procedure
A thin layer of the cornea is sliced off to create a flap.
The laser beam to hit the stroma directly.
The flap is then replaced into its original position.

23. Laser
Epithelial
Keratomileusis
(LASEK)
• Similar to LASIK but a flap in the
epithelial layer only.
• LASEK is used mostly for patients with
a thin cornea.

24. Laser Epithelial Keratomileusis (LASEK)
Similar to LASIK but a flap in the epithelial
layer only.
LASEK is used mostly for patients with a thin
cornea.

25. SMILE
• SMILE is the 3rd generation of corneal refractive procedures.
• Without a flap.
• Can correct high diopters up to 10 D
• The procedure divided into two steps: the femtosecond laser
application and the manual removal of the lenticule.
• Advantages: no flap complications, preservation of the corneal
nerves, less dry eye syndrome, greater integrity of the upper corneal
layers

26. SMILE Procedure video

27. Preoperative
Evaluation

28. Preoperative Evaluation
Involves
• Screening
• History taking
• Preoperative examination
• counselling

29. Ophthalmic Examination
• Visual acuity
• Refraction
• Tear secretion rate test
• Topographic analysis
• Pachymetry

30. Systemic Contraindications
• Diabetes mellitus
• Pregnancy
• Autoimmune / connective tissue disorders
• Abnormal wound healing
• Systemic Infection (HIV,TB)

31. Ophthalmic Contraindications
• Disorders that may be exacerbated by PRK (Herpes Zoster &
Glaucoma
• Dry eye
• Abnormal corneal shape (High irregular astigmatism & Keratoconus)

32. Cryotherapy

33. Cryotherapy
• The term "cryotherapy" comes from the Greek Cryo-
meaning cold.
• For Ophthalmological uses the liquid nitrogen (Boiling point
−195.6 ̊C), it the most effective in cell destruction.
• Is a technique that uses an extreme cold produced by an
instrument to freeze and destroy abnormal tissue.
• The cold probe is applied to the tissue.

34. Cryotherapy indication
• Chronic trichiasis.
• Basal cell carcinoma of eyelids.
• Retinoblastoma.
• Vernal keratoconjunctivitis.
• Pterygium.
• Retinopathy of prematurity.

35. Complications of Cryotherapy
• Most complications are related to surgeon inexperience.
• Prolonged contact with surface tissue, leading to an over-freeze.
Corneal endothelial damage
Uveitis
Temporary chemosis
Subconjunctival hemorrhage
Paralysis of extra ocular muscles

36. References
• Wollensak, G., Spoerl, E., & Seiler, T. (2003). Riboflavin/ultraviolet-A–induced collagen crosslinking for the treatment of
keratoconus. American journal of ophthalmology, 135(5), 620-627.
• Andreanos, K. D., Hashemi, K., Petrelli, M., Droutsas, K., Georgalas, I., & Kymionis, G. D. (2017). Keratoconus treatment
algorithm. Ophthalmology and therapy, 6(2), 245-262.
• web site: www.aoa.org/news/clinical-eye-care/fda-approves-first-corneal-cross-linking-system-for-treatment.
• Dhawan, S., Rao, K., & Natrajan, S. (2011). Complications of corneal collagen cross-linking. Journal of ophthalmology, 2011.
• Mounir, A., Radwan, G., Farouk, M. M., & Mostafa, E. M. (2018). Femtosecond-assisted intracorneal ring segment complications in
keratoconus: from novelty to expertise. Clinical Ophthalmology (Auckland, NZ), 12, 957.
• Miruna, N., Andrei, F., Vasile, F. M., & Eugen, R. (2016). Smile–the next generation of laser vision correction. Romanian journal of
ophthalmology, 60(1), 6.
• Vega-Estrada, A., & Alio, J. L. (2016). The use of intracorneal ring segments in keratoconus. Eye and Vision, 3(1), 8.
• Tehrani, S., & Fraunfelder, F. W. (2013). Cryotherapy in ophthalmology. Open Journal of Ophthalmology, 3(04), 103.

37. Thank you