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

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,

Femtosecond Laser Assisted Lamellar Keratoplasties 83

In the second surgical phase, performed in the operatory room, the donor button is cut from an entire cornea delivered by an Italian Corneal Bank with a corneal trephine (Hanna suction system, Moria, France) 0.25mm wider than the receiving bed (Fig. 6); then, after Descemet/endothelium layers manual stripping, the donor button is sutured on receiving

Fig. 6. Second step of Femto-DALK technique in operatory room: Suturing of the donor lamella after Descemet/endothelium layer manual stripping on recipient bed with 16 radial

receiving bed cut with the femtolaser, that required a conversion to PK.

During the surgical procedure, two patients experienced a perforation performing the

In another case, a microperforation occurred during the PTK ablation, that was managed with air injection in AC, and then the procedure was carried out without any further

One week after surgery a clear graft is shown in all cases, with an interface very hard to detect at slit lamp examination (Fig. 7). In all patients, one month after surgery the mean BSCVA was 0.40, three months later was 0.60, and at the one-year follow-up mark a clear graft and a regular astigmatism was reached (Figure 8), and BSCVA resulted 0.74. Two years after surgery, all patients experience stable results in both UCVA (0.43 ± 0.25SD) and BSCVA (0.84 ± 0.13SD), showing the validity of this femtolaser assisted DALK technique

Fig. 7. Slit lamp examination (on left) at first week shows a clear graft with 16 radial nylon

stitches; the topography analysis shows a regular "with the rule" astigmatism.

stromal bed using 16 radial 10/0 nylon stitches.

nylon stitches.

(Figure 9).

complication in operatory room.

replacing it with a healthy stromal tissue, and restoring in that way a normal corneal thickness and shape 11-13. However, there are some drawbacks to DALK, including the great difficulty of the manual intrastromal dissection and the fact that the procedure rarely achieves precision, resulting in low visual acuity and poor optical quality, especially if Descemet's membrane is not reached with the Big Bubble technique. There is also a high risk of micro- or macro-perforation 13-15, often requiring a conversion to Penetrating Keratoplasty. Many of these problems could be focused by the femtosecond laser assisted deep anterior lamellar keratoplasty (femto-DALK) procedure created to open this difficult surgery to every surgical skills.

In keratoconus patients, the goal is to utilise a surgical option that could be compared in results to manual descemetic DALK, preserving the health and integrity of the corneal endothelium layer.

#### **3.1 Clinical experience with Femto-DALK**

This technique was performed on 21 eyes of 21 patients, with advanced keratoconus with a mean corneal power of 53.2D ± 6.08SD and a mean corneal topographic astigmatism of 4.3D ± 2.82SD. Mean UCVA was 0.1 ± 0.05SD, and mean BSCVA was 0.33 ± 0.15SD; mean SE was -3.73 ± 2.65SD, and mean preoperative pachymetry was 361.19μm ±46.85SD.

#### **3.2 Surgical procedure**

The new technique of DALK assisted by a femtosecond laser has been planned in two surgical phases.

During the first phase, performed in the laser room, a deep 8.2mm wide stromal cut on receiving bed is performed with a 60 kHz femtosecond laser (IntraLase, AMO, USA), leaving at least 100µm of residual stromal bed, on the base of the pachymetric parameters of the patient (optical pachymetry evaluated by Orbscan II). Then, a +4 D spherical hyperopic PRK ablation with an optical zone of 6.5 mm (8.5 mm of maximum ablation diameter), to reduce the peripheral bed thickness in the way to reach a more uniform stromal bed thickness, followed by a 40-60 µm, 7.0mm wide, PTK ablation with fluid mask to reach as much as possible the Descemet's layer, is carried out with an excimer laser (Technolas 217C, B&L, USA) on the residual stromal bed (Fig. 5).

Fig. 5. First step of Femto-DALK technique: preparation of recipient bed in the laser room: ("----") Femtosecond laser cut as deep as possible, leaving at least 100microns of stromal residual bed; ("….") Excimer laser ablation +3/4 sph PRK to reduce peripheral bed thickness; ("….") Excimer laser 40-60 microns PTK to reach Descemet/epithelium layer as near as possible.

replacing it with a healthy stromal tissue, and restoring in that way a normal corneal thickness and shape 11-13. However, there are some drawbacks to DALK, including the great difficulty of the manual intrastromal dissection and the fact that the procedure rarely achieves precision, resulting in low visual acuity and poor optical quality, especially if Descemet's membrane is not reached with the Big Bubble technique. There is also a high risk of micro- or macro-perforation 13-15, often requiring a conversion to Penetrating Keratoplasty. Many of these problems could be focused by the femtosecond laser assisted deep anterior lamellar keratoplasty (femto-DALK)

In keratoconus patients, the goal is to utilise a surgical option that could be compared in results to manual descemetic DALK, preserving the health and integrity of the corneal

This technique was performed on 21 eyes of 21 patients, with advanced keratoconus with a mean corneal power of 53.2D ± 6.08SD and a mean corneal topographic astigmatism of 4.3D ± 2.82SD. Mean UCVA was 0.1 ± 0.05SD, and mean BSCVA was 0.33 ± 0.15SD; mean SE was

The new technique of DALK assisted by a femtosecond laser has been planned in two

During the first phase, performed in the laser room, a deep 8.2mm wide stromal cut on receiving bed is performed with a 60 kHz femtosecond laser (IntraLase, AMO, USA), leaving at least 100µm of residual stromal bed, on the base of the pachymetric parameters of the patient (optical pachymetry evaluated by Orbscan II). Then, a +4 D spherical hyperopic PRK ablation with an optical zone of 6.5 mm (8.5 mm of maximum ablation diameter), to reduce the peripheral bed thickness in the way to reach a more uniform stromal bed thickness, followed by a 40-60 µm, 7.0mm wide, PTK ablation with fluid mask to reach as much as possible the Descemet's layer, is carried out with an excimer laser (Technolas 217C,

Fig. 5. First step of Femto-DALK technique: preparation of recipient bed in the laser room: ("----") Femtosecond laser cut as deep as possible, leaving at least 100microns of stromal residual bed; ("….") Excimer laser ablation +3/4 sph PRK to reduce peripheral bed thickness; ("….") Excimer laser 40-60 microns PTK to reach Descemet/epithelium layer as

procedure created to open this difficult surgery to every surgical skills.


endothelium layer.

**3.2 Surgical procedure** 

surgical phases.

near as possible.

**3.1 Clinical experience with Femto-DALK** 

B&L, USA) on the residual stromal bed (Fig. 5).

In the second surgical phase, performed in the operatory room, the donor button is cut from an entire cornea delivered by an Italian Corneal Bank with a corneal trephine (Hanna suction system, Moria, France) 0.25mm wider than the receiving bed (Fig. 6); then, after Descemet/endothelium layers manual stripping, the donor button is sutured on receiving stromal bed using 16 radial 10/0 nylon stitches.

Fig. 6. Second step of Femto-DALK technique in operatory room: Suturing of the donor lamella after Descemet/endothelium layer manual stripping on recipient bed with 16 radial nylon stitches.

During the surgical procedure, two patients experienced a perforation performing the receiving bed cut with the femtolaser, that required a conversion to PK.

In another case, a microperforation occurred during the PTK ablation, that was managed with air injection in AC, and then the procedure was carried out without any further complication in operatory room.

One week after surgery a clear graft is shown in all cases, with an interface very hard to detect at slit lamp examination (Fig. 7). In all patients, one month after surgery the mean BSCVA was 0.40, three months later was 0.60, and at the one-year follow-up mark a clear graft and a regular astigmatism was reached (Figure 8), and BSCVA resulted 0.74. Two years after surgery, all patients experience stable results in both UCVA (0.43 ± 0.25SD) and BSCVA (0.84 ± 0.13SD), showing the validity of this femtolaser assisted DALK technique (Figure 9).

Fig. 7. Slit lamp examination (on left) at first week shows a clear graft with 16 radial nylon stitches; the topography analysis shows a regular "with the rule" astigmatism.

Femtosecond Laser Assisted Lamellar Keratoplasties 85

Fig. 10. Optical Coherence Tomography of a Femto-DALK shows a regular residual bed thickness 1 month after surgery (the yellow arrows mark the residual stromal bed).

a b

Fig. 11. Case of stromal reject 15 months after surgery: a. Clear graft two weeks after surgery; b. Clear graft before all suture removal nine months after surgery; c. Stromal rejection 15 months postoperatively with neovessels and massive stromal oedema; d. Complete resolution of the stromal rejection after two weeks of massive topical steroid

c d

therapy.

Fig. 8. Slit lamp examination (on the left) at 12 months shows a clear graft after all sutures removal. The topography analysis (on the right) shows a regular bow-tie "against the rule" astigmatism.

(the yellow star marks the mean suture removal period)

Fig. 9. Visual acuity results of Femto-DALK after 2 years (Mean follow-up : 32.94 months ±11,50SD)

Postoperative optical pachymetry evaluation with Optical Coherence Tomography (Visante, Carl Zeiss, Jena, Germany) and Confoscan4 showed a mean residual stromal bed thickness of 67.19µm ± 13.19 SD (range: 50 to 85 micron), three months after surgery (Fig.10).

In three cases of our case series, a stromal rejection of the donor lamella occurred at 5, 16 and 18 months after surgery. The stromal reject was resolved in all cases only with topical steroid therapy (Fig. 11). Confocal microscopy analysis with Confoscan4 showed no recipient endothelium involvement, oedema of deep donor lamellar stroma, immunological infiltrates of the anterior stroma of donor lamella, and inflammatory infiltrates and oedema of epithelium of the graft (Fig. 12).

The case observed 5 months after surgery developed four months later an herpetic keratitis of the donor lamella and was removed from the study after nine months of follow-up.

Fig. 8. Slit lamp examination (on the left) at 12 months shows a clear graft after all sutures removal. The topography analysis (on the right) shows a regular bow-tie "against the rule"

Fig. 9. Visual acuity results of Femto-DALK after 2 years (Mean follow-up : 32.94 months

of 67.19µm ± 13.19 SD (range: 50 to 85 micron), three months after surgery (Fig.10).

Postoperative optical pachymetry evaluation with Optical Coherence Tomography (Visante, Carl Zeiss, Jena, Germany) and Confoscan4 showed a mean residual stromal bed thickness

In three cases of our case series, a stromal rejection of the donor lamella occurred at 5, 16 and 18 months after surgery. The stromal reject was resolved in all cases only with topical steroid therapy (Fig. 11). Confocal microscopy analysis with Confoscan4 showed no recipient endothelium involvement, oedema of deep donor lamellar stroma, immunological infiltrates of the anterior stroma of donor lamella, and inflammatory infiltrates and oedema

The case observed 5 months after surgery developed four months later an herpetic keratitis of the donor lamella and was removed from the study after nine months of follow-up.

astigmatism.

±11,50SD)

(the yellow star marks the mean suture removal period)

of epithelium of the graft (Fig. 12).

Fig. 10. Optical Coherence Tomography of a Femto-DALK shows a regular residual bed thickness 1 month after surgery (the yellow arrows mark the residual stromal bed).

Fig. 11. Case of stromal reject 15 months after surgery: a. Clear graft two weeks after surgery; b. Clear graft before all suture removal nine months after surgery; c. Stromal rejection 15 months postoperatively with neovessels and massive stromal oedema; d. Complete resolution of the stromal rejection after two weeks of massive topical steroid therapy.

Femtosecond Laser Assisted Lamellar Keratoplasties 87

Fig. 13. Preparing the donor lamella: division the two lamellae with forceps after donor

a b

c d

Fig. 14. Clinical case of Femto-DSEK (with "taco" technique): Preoperative slit lamp examination shows massive corneal oedema (a); One week postoperative shows corneal oedema, endothelial lamella centred with air in AC (b); one month postoperatively the corneal oedema is reduced (c) and three months postoperatively a clear graft is shown (d) One day postoperatively, the donor lamella resulted in place in 9 cases (Figure 14). In three cases, the donor lamella resulted dislocated (Fig. 15), requiring a second air injection in AC

One month after surgery the BSCVA resulted not so good (mean BSCVA 0.5 ± 0.15 SD) and increased slowly during the follow-up, resulting a little bit higher six months after surgery (

corneal punch.

to reposition it back.

0.58 ± 0.23SD).

Fig. 12. Confoscan 4 confocal microscopy analysis of graft rejection of Femto-DALK: a. no recipient endothelium involvement, b. oedema of deep donor lamellar stroma; c. immunological infiltrates of the anterior stroma of donor lamella; d. inflammatory infiltrates and oedema of epithelium of the graft
