Femtosecond Laser Assisted Keratoplasty
| Status: | Recruiting |
|---|---|
| Healthy: | No |
| Age Range: | 18 - 60 |
| Updated: | 7/11/2015 |
| Start Date: | October 2007 |
| Contact: | Shahzad Mian, MD |
| Email: | smian@umich.edu |
| Phone: | 734-615-5476 |
Penetrating keratoplasty (PKP) or full-thickness corneal transplantation is a common and
highly successful method to restore vision decreased by corneal opacification. Surgery is
performed by using round trephine blades to create matched circumferential incisions in both
the diseased cornea and the donor cornea. Several types of blades are currently available to
create uniform corneal cuts. The donor tissue graft is then secured in place with sutures
which are usually removed postoperatively after one to two years. The primary surgical goals
are the preservation of a clear graft and improvement of vision. Surgical outcomes are
limited by donor-recipient junction mismatch, astigmatism, rejection, infection and wound
dehiscence.
The femtosecond laser is a focusable, infrared laser capable of cutting tissue at various
depths and in a range of patterns, and is currently being used to create corneal lamellar
flaps in LASIK surgery. The laser parameters can be adjusted for submicron precision in
cutting desired diameters, depths and shapes in the cornea, with minimal collateral injury.
This technology is now capable of creating full-thickness corneal trephinations with
customized locking edges at the graft-host junction between the donor and recipient corneas
in Femtosecond Laser-Assisted Keratoplasty (FLAK). This approach may allow for better wound
junction of the donor and recipient corneas, which in turn may also significantly reduce
astigmatism, improve wound healing and visual recovery.
Although the femtosecond laser has been approved by the FDA for use in corneal transplants,
it has not been compared to standard corneal transplant techniques. This pilot study will
help us determine optimal femtosecond laser spot size, separation, fluence, and energy which
result in the best graft-host fit. Surgical eligibility criteria, including preoperative
diagnoses, as well as possible associated medical and ophthalmic conditions for the eventual
multi-center study will be defined. Primary outcome measures, which include corneal
refractive power measurements, serial endothelial-cell counts to assess endothelial survival
and vision-specific quality of life surveys, will be evaluated. The specific aim is to
investigate postoperative physiology and biomechanics after FLAK in human eyes. The
significance is that FLAK presents corneal surgeons with an opportunity to avoid some
problems of PKP and offers a safer and more precise approach to treating visually disabling
diseases secondary to corneal opacification.
highly successful method to restore vision decreased by corneal opacification. Surgery is
performed by using round trephine blades to create matched circumferential incisions in both
the diseased cornea and the donor cornea. Several types of blades are currently available to
create uniform corneal cuts. The donor tissue graft is then secured in place with sutures
which are usually removed postoperatively after one to two years. The primary surgical goals
are the preservation of a clear graft and improvement of vision. Surgical outcomes are
limited by donor-recipient junction mismatch, astigmatism, rejection, infection and wound
dehiscence.
The femtosecond laser is a focusable, infrared laser capable of cutting tissue at various
depths and in a range of patterns, and is currently being used to create corneal lamellar
flaps in LASIK surgery. The laser parameters can be adjusted for submicron precision in
cutting desired diameters, depths and shapes in the cornea, with minimal collateral injury.
This technology is now capable of creating full-thickness corneal trephinations with
customized locking edges at the graft-host junction between the donor and recipient corneas
in Femtosecond Laser-Assisted Keratoplasty (FLAK). This approach may allow for better wound
junction of the donor and recipient corneas, which in turn may also significantly reduce
astigmatism, improve wound healing and visual recovery.
Although the femtosecond laser has been approved by the FDA for use in corneal transplants,
it has not been compared to standard corneal transplant techniques. This pilot study will
help us determine optimal femtosecond laser spot size, separation, fluence, and energy which
result in the best graft-host fit. Surgical eligibility criteria, including preoperative
diagnoses, as well as possible associated medical and ophthalmic conditions for the eventual
multi-center study will be defined. Primary outcome measures, which include corneal
refractive power measurements, serial endothelial-cell counts to assess endothelial survival
and vision-specific quality of life surveys, will be evaluated. The specific aim is to
investigate postoperative physiology and biomechanics after FLAK in human eyes. The
significance is that FLAK presents corneal surgeons with an opportunity to avoid some
problems of PKP and offers a safer and more precise approach to treating visually disabling
diseases secondary to corneal opacification.
Inclusion Criteria:
1. Corneal opacification.
2. Reduced ETDRS-measured, best corrected, distance visual acuity to 20/40 or worse.
3. Ability to participate in follow-up visits.
4. Signed, informed consent.
Exclusion Criteria:
1. Corneal opacification adequately dense to obscure visualization of iris.
2. ETDRS-measured, best-corrected, distance visual acuity of 20/30 or better.
3. Corneal thickness greater than 1200 µm at the 9 mm peripheral zone.
4. Severe corneal thinning including descemetocoele with impending corneal rupture.
5. Prior PKP or incisional surgery that may provide a potential space into which the gas
produced by the procedure can escape.
6. Poor visual potential in the non-study eye (VA of 20/100 or less, without potential
for improvement by the examining ophthalmologist's judgment).
7. History of glaucoma, including steroid response rise in intraocular pressure.
8. Active intraocular inflammation or infection.
9. Age 18 or younger.
10. Unable to return for scheduled follow-up examinations.
11. Other medical condition(s) that will likely prevent long term follow-up.
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