Femtosecond Laser and Microkeratome-Assisted DSAEK
Femtosecond Laser and Microkeratome-Assisted DSAEK
This prospective study comprised 25 eyes from 25 patients with Fuchs endothelial dystrophy (14 eyes) or pseudophakic bullous keratopathy (11 eyes). Exclusion criteria were coexisting non-corneal abnormalities, such as macular degeneration and advanced glaucoma, and history of previous corneal surgery or visually significant corneal scarring. There were no relevant coexisting systemic diseases. Institutional review board approval was obtained and patients were provided with informed consent after the possible consequences of participation had been explained.
Donor corneas were obtained from Fondazione Banca Degli Occhi (Venice, Italy) preserved in organ culture medium at 31°C. Each cornea was mounted on an artificial anterior chamber (ALTK, Moria SA, Antony, France) filled with balanced salt solution (BSS, Alcon, Fort Worth, Texas, USA). Central pachymetry was performed with an ultrasonic pachymeter (CorneoGage Plus 50 MHz; Sonogage, Cleveland, Ohio, USA) after removal of the epithelium. Five readings were averaged. The BSS bottle was elevated to 220 cm and the tubing clamped at 60 cm from the anterior chamber. Two cuts were made. An Intralase FS60 femtosecond laser (Abbott Medical Optics, Santa Ana, California, USA) was used for the first cut and a Moria CBm microkeratome with a 300 μm cutting head was used for the second. The thickness of the first cut was calculated as follows:
*This figure is the sum of the theoretical microkeratome cut thickness (300 μm) plus the desired final graft thickness (110 μm).
Femtosecond settings were full lamellar cut, diameter 9.5 mm, raster energy 1.5 μJ and anterior side cut at 90°. No suction ring was used and docking was straightforward. The first anterior stromal lenticule was easily removed following the femtosecond cut. In no case was manual dissection needed. The second cut was performed immediately afterwards with the 300 μm microkeratome head, keeping the manual rotation speed constant and with total duration of approximately 5 s. The tubing was unclamped from the BSS bottle at 150 cm.
Donor tissue was removed by gently pulling the scleral rim from the top of the anterior chamber and was transferred to an 8.5 mm Hessburg-Barron trephine (Katena Products, Denville, New Jersey, USA).
Recipient preparation and donor insertion were performed as previously described. In brief, the procedure consisted of stripping Descemet's membrane, performing an inferior iridectomy to prevent pupillary block, transferring the graft using a Busin glide (Moria SA) and filling the anterior chamber almost completely with air underneath the graft.
Seventeen patients were pseudophakic preoperatively. Concurrent cataract surgery was performed in eight cases, before the Descemet stripping. Surgeries were performed by one surgeon (JNM). Postoperative medication consisted of ofloxacin 3 mg/ml and dexamethasone 1 mg/ml six times a day for 2 weeks and then tapered according to clinical response.
Graft thickness was measured at 1, 3 and 6 months using anterior segment optical coherence tomography (Spectralis Anterior Segment Module, Heidelberg, Germany). The scanning line was positioned on the 180° axis into the corneal vertex and measurements were taken at the vertex and at 3 mm on either side to obtain peripheral thickness (figure 1).
(Enlarge Image)
Figure 1.
Anterior segment optical coherence tomography performed 1 month after Descemet stripping automated endothelial keratoplasty (femtosecond and microkeratome assisted) showing a posterior lamellar graft with a central thickness of 60 μm, temporal thickness of 88 μm and nasal thickness of 81 μm. Access the article online to view this figure in colour.
Corrected distance visual acuity (CDVA) with subjective refraction was recorded preoperatively and at 1, 3 and 6 months after surgery. Baseline donor endothelial cell density (ECD) was provided by the eye bank and was measured postoperatively with specular microscopy (Tomey EM-3000, Nagoya, Japan).
Statistical analysis was performed with IBM SPSS Statistics V.19 (SPSS Inc, Chicago, USA). Repeated measures analysis of variance with Bonferroni correction for multiple comparisons was used after verifying that data did not significantly deviate from normal distribution (Kolmogorov–Smirnov test). All results with p<0.05 were considered statistically significant.
Materials and Methods
Patients
This prospective study comprised 25 eyes from 25 patients with Fuchs endothelial dystrophy (14 eyes) or pseudophakic bullous keratopathy (11 eyes). Exclusion criteria were coexisting non-corneal abnormalities, such as macular degeneration and advanced glaucoma, and history of previous corneal surgery or visually significant corneal scarring. There were no relevant coexisting systemic diseases. Institutional review board approval was obtained and patients were provided with informed consent after the possible consequences of participation had been explained.
Surgical Technique
Donor corneas were obtained from Fondazione Banca Degli Occhi (Venice, Italy) preserved in organ culture medium at 31°C. Each cornea was mounted on an artificial anterior chamber (ALTK, Moria SA, Antony, France) filled with balanced salt solution (BSS, Alcon, Fort Worth, Texas, USA). Central pachymetry was performed with an ultrasonic pachymeter (CorneoGage Plus 50 MHz; Sonogage, Cleveland, Ohio, USA) after removal of the epithelium. Five readings were averaged. The BSS bottle was elevated to 220 cm and the tubing clamped at 60 cm from the anterior chamber. Two cuts were made. An Intralase FS60 femtosecond laser (Abbott Medical Optics, Santa Ana, California, USA) was used for the first cut and a Moria CBm microkeratome with a 300 μm cutting head was used for the second. The thickness of the first cut was calculated as follows:
*This figure is the sum of the theoretical microkeratome cut thickness (300 μm) plus the desired final graft thickness (110 μm).
Femtosecond settings were full lamellar cut, diameter 9.5 mm, raster energy 1.5 μJ and anterior side cut at 90°. No suction ring was used and docking was straightforward. The first anterior stromal lenticule was easily removed following the femtosecond cut. In no case was manual dissection needed. The second cut was performed immediately afterwards with the 300 μm microkeratome head, keeping the manual rotation speed constant and with total duration of approximately 5 s. The tubing was unclamped from the BSS bottle at 150 cm.
Donor tissue was removed by gently pulling the scleral rim from the top of the anterior chamber and was transferred to an 8.5 mm Hessburg-Barron trephine (Katena Products, Denville, New Jersey, USA).
Recipient preparation and donor insertion were performed as previously described. In brief, the procedure consisted of stripping Descemet's membrane, performing an inferior iridectomy to prevent pupillary block, transferring the graft using a Busin glide (Moria SA) and filling the anterior chamber almost completely with air underneath the graft.
Seventeen patients were pseudophakic preoperatively. Concurrent cataract surgery was performed in eight cases, before the Descemet stripping. Surgeries were performed by one surgeon (JNM). Postoperative medication consisted of ofloxacin 3 mg/ml and dexamethasone 1 mg/ml six times a day for 2 weeks and then tapered according to clinical response.
Outcome Analysis
Graft thickness was measured at 1, 3 and 6 months using anterior segment optical coherence tomography (Spectralis Anterior Segment Module, Heidelberg, Germany). The scanning line was positioned on the 180° axis into the corneal vertex and measurements were taken at the vertex and at 3 mm on either side to obtain peripheral thickness (figure 1).
(Enlarge Image)
Figure 1.
Anterior segment optical coherence tomography performed 1 month after Descemet stripping automated endothelial keratoplasty (femtosecond and microkeratome assisted) showing a posterior lamellar graft with a central thickness of 60 μm, temporal thickness of 88 μm and nasal thickness of 81 μm. Access the article online to view this figure in colour.
Corrected distance visual acuity (CDVA) with subjective refraction was recorded preoperatively and at 1, 3 and 6 months after surgery. Baseline donor endothelial cell density (ECD) was provided by the eye bank and was measured postoperatively with specular microscopy (Tomey EM-3000, Nagoya, Japan).
Statistical analysis was performed with IBM SPSS Statistics V.19 (SPSS Inc, Chicago, USA). Repeated measures analysis of variance with Bonferroni correction for multiple comparisons was used after verifying that data did not significantly deviate from normal distribution (Kolmogorov–Smirnov test). All results with p<0.05 were considered statistically significant.
