**2.3 Surgical procedure**

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(Figure 2). In the second step, performed in the surgery room, the donor lamella was sutured into the receiving stromal bed with 16 radial 10/0 nylon stitches.

To realize the donor lamella, the cut was performed on an entire donor cornea, analyzed and delivered by an ocular tissue bank, positioned on an artificial anterior chamber (Moria, France). Mean lamellar diameter was 8.34mm ± 0.28 SD (range: 8.2 - 8.7mm), and mean lamellar thickness was 353.91µm ± 38.82SD (range: 220 - 400µm). The donor button has been planned thicker than the amount of receiving cornea removed, in way to restore a normal corneal thickness (at least 550 micron), and 0.2 mm larger, in way to avoid too much corneal compression with the sutures and to evade the risk of anterior chamber (AC) reduction after surgery.

Fig. 2. Femtosecond laser cut on recipient bed after docking on the cornea of the patient.

Femtosecond Laser Assisted Lamellar Keratoplasties 81

Analyzing all our cases with the confocal microscopy analysis (Confoscan4), we found that this unsatisfactory visual results were mostly related to the excessive thickness of residual stromal bed (150 microns or more), resulting in a irregular stromal interface (Fig. 4) with dark folds before suture removal (published on "Cornea 2008 Jul; 27(6): 668-72"); few months after suture removal, these findings disappeared gradually with a parallel increase of the BSCVA, setting to 0.64 Snellen at 12 months of follow-up. At two years of follow up the mean BSCVA resulted increased to 0.74 ± 0.18SD. After a three years of follow-up, these visual results resulted quite similar (mean UCVA of 0.48 ± 0.13SD and mean BSCVA of 0.78 ± 0.13SD), confirming the stability of the outcomes during time and the validity of the Femto-ALK technique (Figure 3) and confirming that, comparing to penetrating

keratoplasty (PK), lamellar keratoplasty need more time to stabilize the results.

Fig. 4. Femto-ALK results: a. slit lamp examination 3 months after surgery shows a clear graft with sutures still on; b. Confoscan 4 confocal microscopy analysis at three months shows dark folds of the residual bed stroma related to the slow visual recovery; c. Six months postoperatively slit lamp shows a clear graft and confocal analysis (d) shows

After the quite unsatisfactory results obtained with the Femto-ALK technique, in keratoconic cases, We designed a new surgical technique trying to duplicate the superior results obtained with the descemetic and pre-descemetic DALK techniques: the femtolaser-assisted DALK. Deep Anterior Lamellar Keratoplasty (DALK) has the target of removing all the pathological stromal tissue, maintaining only the Descemet/endothelium layers in the recipient bed,

disappearance of the stromal folds and a healthy endothelium.

**3. Deep Anterior Lamellar Keratoplasty (DALK)** 

Under topical anaesthesia (Ossibuprocaine 4% drops for 4 times), a disposable suction ring was positioned at the sclero-limbal margin to stabilize the eye. After the docking, the femtosecond laser cut (Figure 2) on receiving corneal stroma was performed to leave at least 200µm residual stromal bed (mean stromal cut deepness of 243.91µm ±51.59SD, with a mean diameter of 8.13mm ±0.37 SD, and mean residual stromal bed of 181.61µm ± 57.78SD).

After stromal laser cut execution, the patient was carried in the surgery room where the corneal button was removed with a blunt spatula leaving the clear stromal residual bed. Then, the donor lamella was first secured in the recipient bed with four 10/0 nylon cardinal sutures at the 6, 12, 9 and 3 o'clock positions, and subsequently it was sutured with twelve more 10/0 nylon radial stitches. Intraoperatively, corneal astigmatism was evaluated with a corneal disposable keratometer, (Janach, Como, Italy) and suture adjustment, if required, was performed. At the end of surgery, a soft contact lens was placed on the eye surface to help restoring of corneal epithelium. Topical antibiotics (Nethylmicine), steroids (Desamethasone 0.18%) and artificial tear drops (Hyaluronate sodium 0.2%) were applied several times a day, and then tapered and titrated, basing on the corneal transparency and scarring of the surgical wound.

The surgical plannings have been realized in all cases basing on the accurate preoperative pachymetric values found with optical pachymetry (Confoscan 4, Nidek technologies, Tokyo, Japan; and Orbscan II, Bausch & Lomb, CA, USA).

In all the cases performed, the surgery restored a clear cornea from the first week after surgery with an interface hard to detect at the slit lamp examination.

The postoperative corneal thickness (mean corneal pachymetry: 542.48µm ± 33.20SD), curvature (mean K reading: 44.32D ± 13.50SD) and shape resulted nearer to physiologic values. Nevertheless, the results in visual acuity obtained with the Femto-ALK were not so brilliant as planned, especially in the keratoconic eyes, with a very slow recovery time. Three months after surgery, mean BSCVA was 0.30, increasing to 0.40 after complete suture removal six months later, and stabilizing 12 months postoperatively to 0.64 (the Figure 3 showed the BSCVA during follow-up).

Fig. 3. Visual acuity results three years after Femto-ALK. The yellow star marks the mean removal suture period.

Under topical anaesthesia (Ossibuprocaine 4% drops for 4 times), a disposable suction ring was positioned at the sclero-limbal margin to stabilize the eye. After the docking, the femtosecond laser cut (Figure 2) on receiving corneal stroma was performed to leave at least 200µm residual stromal bed (mean stromal cut deepness of 243.91µm ±51.59SD, with a mean diameter of 8.13mm ±0.37 SD, and mean residual stromal bed of 181.61µm ± 57.78SD). After stromal laser cut execution, the patient was carried in the surgery room where the corneal button was removed with a blunt spatula leaving the clear stromal residual bed. Then, the donor lamella was first secured in the recipient bed with four 10/0 nylon cardinal sutures at the 6, 12, 9 and 3 o'clock positions, and subsequently it was sutured with twelve more 10/0 nylon radial stitches. Intraoperatively, corneal astigmatism was evaluated with a corneal disposable keratometer, (Janach, Como, Italy) and suture adjustment, if required, was performed. At the end of surgery, a soft contact lens was placed on the eye surface to help restoring of corneal epithelium. Topical antibiotics (Nethylmicine), steroids (Desamethasone 0.18%) and artificial tear drops (Hyaluronate sodium 0.2%) were applied several times a day, and then tapered and titrated, basing on the corneal transparency and

The surgical plannings have been realized in all cases basing on the accurate preoperative pachymetric values found with optical pachymetry (Confoscan 4, Nidek technologies,

In all the cases performed, the surgery restored a clear cornea from the first week after

The postoperative corneal thickness (mean corneal pachymetry: 542.48µm ± 33.20SD), curvature (mean K reading: 44.32D ± 13.50SD) and shape resulted nearer to physiologic values. Nevertheless, the results in visual acuity obtained with the Femto-ALK were not so brilliant as planned, especially in the keratoconic eyes, with a very slow recovery time. Three months after surgery, mean BSCVA was 0.30, increasing to 0.40 after complete suture removal six months later, and stabilizing 12 months postoperatively to 0.64 (the Figure 3

**Mean Visual Acuity** 

**0,08**

**0,05 0,09**

**0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1**

**Snellen**

removal suture period.

**0,13**

**0,29 0,25**

**0,18**

**Preop 1 3 6 9 12 24 36**

Fig. 3. Visual acuity results three years after Femto-ALK. The yellow star marks the mean

**0,35**

**0,23**

**0,45**

**0,45**

**0,65**

**0,46 0,48**

**0,74 0,78**

**UCVA BCVA**

scarring of the surgical wound.

showed the BSCVA during follow-up).

Tokyo, Japan; and Orbscan II, Bausch & Lomb, CA, USA).

surgery with an interface hard to detect at the slit lamp examination.

Analyzing all our cases with the confocal microscopy analysis (Confoscan4), we found that this unsatisfactory visual results were mostly related to the excessive thickness of residual stromal bed (150 microns or more), resulting in a irregular stromal interface (Fig. 4) with dark folds before suture removal (published on "Cornea 2008 Jul; 27(6): 668-72"); few months after suture removal, these findings disappeared gradually with a parallel increase of the BSCVA, setting to 0.64 Snellen at 12 months of follow-up. At two years of follow up the mean BSCVA resulted increased to 0.74 ± 0.18SD. After a three years of follow-up, these visual results resulted quite similar (mean UCVA of 0.48 ± 0.13SD and mean BSCVA of 0.78 ± 0.13SD), confirming the stability of the outcomes during time and the validity of the Femto-ALK technique (Figure 3) and confirming that, comparing to penetrating keratoplasty (PK), lamellar keratoplasty need more time to stabilize the results.

Fig. 4. Femto-ALK results: a. slit lamp examination 3 months after surgery shows a clear graft with sutures still on; b. Confoscan 4 confocal microscopy analysis at three months shows dark folds of the residual bed stroma related to the slow visual recovery; c. Six months postoperatively slit lamp shows a clear graft and confocal analysis (d) shows disappearance of the stromal folds and a healthy endothelium.
