Femtosecond Laser-Assisted Keratoplasty
Ahmed Nagy Fouad;
Abstract
The advent of the femtosecond laser as an ocular surgical tool offers the potential for more finite control and precision in corneal surgery. With the use of proprietary software, femtosecond lasers are currently able to be programmed to create precise corneal incisions in almost any plane while minimally distorting corneal tissue.
The definition of a femtosecond is 10-15 seconds, Femtosecond lasers produce a tissue interaction, known as photodisruption and the effect of photodisruption on tissue varies as infrared laser energy decreases from the level of micro- to nanoJoules.
There are different commercially available femtosecond lasers (IntraLase, Femtec, VisuMax, Femto LDV).
Femtosecond laser assisted keratoplasty includes:
1. FEMTOSECOND LASER–ASSISTED PENETRATING KERATOPLASTY.
2. FEMTOSECOND LASER–ASSISTED LAMELLAR KERATOPLASTY.
The femtosecond trephination increases the precision and practicality of PK procedures because of the highly reproducible dimensions of the cuts made in donor and host tissues, such procedures result in a better fit between the donor tissue and the recipient cornea, as well as the creation of a larger contact area at the donor-host junction. These features may result in faster and better wound healing, as well as reduced suture-induced astigmatism, thereby promoting more rapid visual recovery.
Increased cost , additional time requirement , and logistical problems are the main disadvantages of femtosecond laser-assisted keratoplasty.
- 105 -
The open-sky surgical exposure like PKP leaves very little protection should an expulsive choroidal hemorrhage occur intraoperatively. Postoperatively, even years after PKP, the full-thickness graft-host junction never heals to the original corneal strength. The large circumferential wound is thus an Achilles heel that is notoriously susceptible to traumatic dehiscence, often resulting in severe loss of vision.
Lamellar keratoplasty is an alternative to PK that works to remove and replace most of the diseased stroma with a graft, leaving intact the patient's own Descemet's membrane and endothelial cells, avoiding endothelial rejection .
Anterior LKPs are done mostly for optical and tectonic purposes in corneas with healthy endothelium.
The Femto-ALK surgical technique has been realized in two surgical steps: The first step was performed in the laser room where a femtosecond laser cut was created on both donor and receiving cornea. In the second step, performed in the surgery room, the donor lamella was sutured into the receiving stromal bed.
Femtosecond laser corneal cutting may offer greater safety, reproducibility, predictability, and flexibility. Moreover, the risks of irregular cutting and microperforation are reduced.
FSALK provides many advantages over the conventional PK and DALK, with improved visual outcome and emmetropization of the manifest refraction rather than inducing ametropia and irregular astigmatism as with PK and DALK procedures.
FSLK is safer in comparison with microkeratome-assisted ALK, and, in theory, the smooth interface made by the FSLK should provide better visual quality; however, this theory needs to be proven by a future comparative prospective study.
Endothelial keratoplasty (EK) is an exciting development in the field of corneal transplantation that allows selective replacement of diseased endothelium.
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A significant advantage of the use of the femtosecond laser in DSEK is that the laser preparation of the donor tissue can be performed in an automated and standardized fashion, which reduces the technical difficulties involved in manual dissection of a posterior corneal disk. Unlike a microkeratome posterior corneal disk, which is prepared at the time of transplantation, the femtosecond-laser–prepared lamellar interface of the disk can be performed up to 3 weeks before the corneal transplantation.
The BSCVA was significantly better in the PK compared with the FS DSEK, Although astigmatism was significantly higher in the PK, the percentage of patients with symptoms of double vision or distorted vision was comparable between the FS DSEK and PK groups.
Due to lack of long term follow-up and small case number
The definition of a femtosecond is 10-15 seconds, Femtosecond lasers produce a tissue interaction, known as photodisruption and the effect of photodisruption on tissue varies as infrared laser energy decreases from the level of micro- to nanoJoules.
There are different commercially available femtosecond lasers (IntraLase, Femtec, VisuMax, Femto LDV).
Femtosecond laser assisted keratoplasty includes:
1. FEMTOSECOND LASER–ASSISTED PENETRATING KERATOPLASTY.
2. FEMTOSECOND LASER–ASSISTED LAMELLAR KERATOPLASTY.
The femtosecond trephination increases the precision and practicality of PK procedures because of the highly reproducible dimensions of the cuts made in donor and host tissues, such procedures result in a better fit between the donor tissue and the recipient cornea, as well as the creation of a larger contact area at the donor-host junction. These features may result in faster and better wound healing, as well as reduced suture-induced astigmatism, thereby promoting more rapid visual recovery.
Increased cost , additional time requirement , and logistical problems are the main disadvantages of femtosecond laser-assisted keratoplasty.
- 105 -
The open-sky surgical exposure like PKP leaves very little protection should an expulsive choroidal hemorrhage occur intraoperatively. Postoperatively, even years after PKP, the full-thickness graft-host junction never heals to the original corneal strength. The large circumferential wound is thus an Achilles heel that is notoriously susceptible to traumatic dehiscence, often resulting in severe loss of vision.
Lamellar keratoplasty is an alternative to PK that works to remove and replace most of the diseased stroma with a graft, leaving intact the patient's own Descemet's membrane and endothelial cells, avoiding endothelial rejection .
Anterior LKPs are done mostly for optical and tectonic purposes in corneas with healthy endothelium.
The Femto-ALK surgical technique has been realized in two surgical steps: The first step was performed in the laser room where a femtosecond laser cut was created on both donor and receiving cornea. In the second step, performed in the surgery room, the donor lamella was sutured into the receiving stromal bed.
Femtosecond laser corneal cutting may offer greater safety, reproducibility, predictability, and flexibility. Moreover, the risks of irregular cutting and microperforation are reduced.
FSALK provides many advantages over the conventional PK and DALK, with improved visual outcome and emmetropization of the manifest refraction rather than inducing ametropia and irregular astigmatism as with PK and DALK procedures.
FSLK is safer in comparison with microkeratome-assisted ALK, and, in theory, the smooth interface made by the FSLK should provide better visual quality; however, this theory needs to be proven by a future comparative prospective study.
Endothelial keratoplasty (EK) is an exciting development in the field of corneal transplantation that allows selective replacement of diseased endothelium.
- 106 -
A significant advantage of the use of the femtosecond laser in DSEK is that the laser preparation of the donor tissue can be performed in an automated and standardized fashion, which reduces the technical difficulties involved in manual dissection of a posterior corneal disk. Unlike a microkeratome posterior corneal disk, which is prepared at the time of transplantation, the femtosecond-laser–prepared lamellar interface of the disk can be performed up to 3 weeks before the corneal transplantation.
The BSCVA was significantly better in the PK compared with the FS DSEK, Although astigmatism was significantly higher in the PK, the percentage of patients with symptoms of double vision or distorted vision was comparable between the FS DSEK and PK groups.
Due to lack of long term follow-up and small case number
Other data
| Title | Femtosecond Laser-Assisted Keratoplasty | Other Titles | ليزر الفيمتو ثانية في جراحة ترقيع القرنيةَ | Authors | Ahmed Nagy Fouad | Issue Date | 2015 |
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