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OSTEO-ODONTO-KERATOPROSTHESIS
Contents
Introduction
Cornea
Corneal transplantation
Penetrating keratoplasty
Lamellar keratoplasty
What is OOKP?
When is it done?
Procedure
Advantages
Conclusion
Reference
Cornea
Transparent front part of the eye that covers iris, pupil and anterior chamber.
Refractive power =43 diopters
Has unmyelinated nerve endings sensitive to touch, temperature and chemicals
Doesn t contain blood vessels so as to maintain the transparency.
Diameter of about 11.5 mm and a thickness of 0.5 0.6 mm in the center and 0.6 0.8 mm at the periphery.
cornea contd.
Main features-transparency, avascularity, the presence of immature resident immune cells
5 layers
1- Corneal epithelium
2-Bowman s layer
3-Corneal stroma
4-Descemet's membrane
5-Corneal endothellium
Corneal transplantation
Also known as corneal grafting
It is a surgical procedure where damaged or diseased cornea is replaced by donated corneal tissue.
Can be replaced entirely(penetrating keratoplasty) or in part(lamellar keratoplasty)
Corneal transplantation
The graft has been removed from a recently deceased individual with no known diseases or other factors that may affect the viability of the donated tissue or the health of the recipient
Penetrating keratoplasty
A trephine is then placed over the cornea to cut the host cornea, which removes a circular disc of the patient cornea.
The trephine is then removed a circular graft is cut from the donor cornea.
Once this is done, the surgeon returns to the patient's eye and removes the host cornea.
Penetrating keratoplasty contd.
The donor cornea is then brought into the surgical field and maneuvered into place with forceps.
Once in place, the surgeon will fasten the cornea to the eye with a stitch.
Lamellar keratoplasty
Only 90% of the cornea is transplanted
The patient s endothelium and descement membrane is not removed
Visual acuity is not as sharp as that of penetrating keratoplasty.
Chances of corneal rejection are less here.
What is OOKP?
Also known as "Tooth in eye" surgery
originated by Prof. Benedetto Strampelli in Italy in 1960s .
Prof. Giancarlo Falcinelli of Italy has refined and improved the procedure.
It is a procedure which aims at sight restoration for patients with the most severe type of corneal and ocular surface diseases, for whom other treatments would not be useful.
OOKP
It involves creating a support for an artificial cornea from the patient s own tooth and the surrounding bone .
The results have been encouraging and many patients have been able to maintain their vision since their operations more than 20 years ago.
OOKP
Includes removal of a tooth from the patient or a donor
Then, a lamina of tissue cut from the tooth is drilled and the hole is fitted with optics.
The lamina is grown in the patients' cheek for a period of months and then is implanted upon the eye.
OOKP
The artificial cornea is made of hard plastic.
For the plastic prosthesis to retain in the eye, tissues from the patient s own body are used.
The tooth is ideal because it has a hard part to which the cylinder can be fixed and also it resides in the mouth where it co-exists with soft tissues, as in the eye.

When is it done?
Pemphigoid
Chemical burns
Stevens-Johnson syndrome
Lyell syndrome
Trachoma
Corneal graft failure
Procedure
OOKP is a complex two stage Operation
Stage 1 of the surgery involves 5 separate procedures:
The eye is opened up and the entire inner surface of the eyelids, corneal surface and all scar tissue is removed
Inner mucosal lining of the cheek is transplanted onto the new surface of the eye
A canine or premolar tooth and part of the adjacent bone and ligaments are removed
A bolt-shaped structure is fashioned from the tooth-bone complex which is fitted with a plastic optical cylinder
The tooth-bone-cylinder complex is implanted into the patient's cheek to grow a new blood supply
Procedure (contd.)
Stage 2 (about 4 months later) involves 2 separate procedures:
The cheek mucosal lining over the eye is opened and the inner contents of the eye are removed
The tooth-bone-cylinder complex is removed from the cheek and inserted into the eye, the mucosal cheek lining is replaced over the implant.
At the end of the procedure, light can now enter through the plastic cylinder, and the patient is able to see through this cylinder with good vision
Removal of iris and lens and the preparation of the osteo-dental lamina complex.
Preparation of buccal mucosal surface
Implantation of complex.
Advantages
Permanent fixation of an acrylic lens
Long-term retention of the prosthesis due to its complete biological compatibility as far as other pathological conditions do not occur.
Conclusion
Despite the complex nature of the operation and possible complications OOKP offers the hope of visual improvement for patients with severe anterior segment disease. Future studies with longer follow-ups to evaluate its efficacy and safety are warranted.
Reference
http://spingerlinkcontent/f6823p005481210q
http://vision-institutetechniques/ptk.html
http://science.howstuffworksnews-item94.htm
wihrd.soton.ac.uk/projx/signpost/steers/STEER_2001(6).pdf
http://dro.hs.columbia.edu/icrs.html
Essentials in ophthalmology, G.K Krieglstein & R.N Weinreb
A text book of Medical physiology, Guyton and Hall, 10th edition