Microkeratome Head Research Articles

A New Technique for Harvesting Limbal Stem Cell Tissue for Transplantation Using an Automated Microkeratome and a Novel Globe-Fixation System.

To introduce an unprecedented technique, instrumentation, and setup for the superficial limbus harvest from the human cadaver donor whole globe. We studied several superficial limbus harvest alternatives, developed a preferred approach with our available instruments, and optimized it on a handful of (seropositive) cadaver donors of whole globes. The globe was pressurized to about normal intraocular pressure by viscoelastic injection through the optic nerve stump. The globe was then mounted on a dynamic globe fixator that maintained a negative pressure in its stabilizing socket. Exertion of the negative pressure effectively elevated globe intraocular pressure (to over 40 mm Hg) and made the corneoscleral wall tight. The socket was then held tilted to the left side for about 35 to 40 degrees to put the limbal zone horizontally and mildly "chin-up." Next, the microkeratome was put on the uppermost and exposed limbus of the globe and activated, and the socket was rotated clockwise under the microkeratome head and its oscillating blade, allowing an effective 360-degree revolution of the microkeratome head around the limbal belt (for a right-handed operator and a counterclockwise cut). We consistently succeeded in peeling intact 360-degree strips of the smooth superficial limbus by using blades with varying depths. Our method can be further equipped and optimized and be used by the eye banks and the surgeons for keratolimbal grafting as a more efficient limbal stem cell tissue harvest technique.

Intraoperative optical coherence tomography-guided donor corneal tissue assessment and preparation.

To evaluate the role of intraoperative optical coherence tomography (i-OCT) in donor grading, selection, and preparation during different types of keratoplasty. Seventy-one consecutive donor corneas collected over 6 months, after clinical grading, were observed by an experienced corneal surgeon under an i-OCT equipped microscope. The donor preparation (manual/automated) for different types of keratoplasty procedures was also undertaken under i-OCT. The mean central corneal thickness of optical and nonoptical grade tissues was 533 ± 19 and 662 ± 52 μm, respectively. The i-OCT-based grading matched with clinical grading in 98.5% cases. Irregular thickness, anterior stromal hyperreflectivity, and previous scars were appreciated in 1.4, 1.4, and 7.04% donors, respectively. During Descemet stripping automated endothelial keratoplasty, i-OCT facilitated selection of appropriate microkeratome head for automated donor preparation in all cases, besides allowing manual dissection of partially dissected lenticule, identification of site of inadvertent perforation, and eccentric trephination in one case each. During Descemet membrane endothelial keratoplasty, i-OCT-based assessment of preexisting scar (five cases) guided careful tissue selection (2/5) and preparation. During predescemetic endothelial keratoplasty, precise needle advancement allowed successful type-1 bubble formation in all cases. All manually punched donors demonstrated an extra endothelial ledge, while those with automated preparation showed tapering donor margins. i-OCT might serve as a useful imaging tool for objective assessment of donor characteristics. The modality may complement clinical evaluation for donor grading, selection, and preparation.

Nomogram for single-pass automated microkeratome graft preparation for ultrathin Descemet stripping automated endothelial keratoplasty.

To create a nomogram including the translational speed of the microkeratome blade, microkeratome head size and precut tissue thickness to predict the postcut thickness for Descemet stripping automated endothelial keratoplasty to obtain the thinnest possible graft. This prospective study incorporated 48 grafts for DSAEK from March 2017 to June 2020. Corneal tissue for DSAEK was prepared by 3 experienced physicians using the Moria Evolution 3E (Moria Inc, Antony, France) microkeratome with 400, 450 and 500μm head sizes. Precut central corneal thickness was measured with a DGH 550 handheld pachymeter (Pachette 2), taking an average of 3 readings. The microkeratome head was selected according to precut tissue thickness. The selected microkeratome head size was 150μm less than the donor cornea thickness. Two translational speeds were used for the microkeratome cuts. One month after surgery, the central lenticular thickness was measured with a Visante® Optical Coherence Tomography caliper (Carl Zeiss Meditec Inc, Germany). A descriptive analysis was performed. Forty-eight donor grafts were prepared. Mean graft thickness was 97.58 ± 29.84μm (range 39-176μm). Of the 48 samples, central graft thickness was < 120µm (81.3%) in 39, < 100µm (58.3%) in 28 and < 80µm (37.5%) in 18 at 1-month follow-up. There were no statically significant differences between translational speeds. A nomogram with an automated microkeratome to obtain thin grafts for DSAEK provided good graft thickness results without donor waste.

Risk factors for early flap misalignment following microkeratome-assisted laser in situ keratomileusis: A retrospective large database analysis.

To determine factors associated with early flap misalignment following microkeratome-assisted laser in situ keratomileusis. This retrospective study included the right eyes of consecutive patients who underwent laser in situ keratomileusis procedure between 2005 and 2016 at Care-Vision Laser Centers, Tel-Aviv, Israel. Patients were divided into two groups according to whether or not they subsequently developed early flap misalignment. A total of 14,582 eyes (mean age of patients: 32.4 ± 10.3 years) were included. Post-laser in situ keratomileusis early flap misalignment developed in 158 eyes (1.1%). Misalignment was more frequent during the spring (32.3% vs 22.8%, p = 0.003) and in a higher operating room temperature (23.34 ± 1.06 vs 22.98 ± 1.26, p < 0.001). In addition, in the misalignment group, there was a higher rate with the of use of the a Moria M2 microkeratome (rather than sub-Bowman's keratomileusis microkeratome) head (55.2% vs 40.5%, respectively, p < 0.001). In a multivariable analysis adjusted for surgeon and year of surgery, high operating room temperature (odds ratio = 1.22, p = 0.006), treatment zone of 9.0 mm (as opposed to smaller treatment zones, odds ratio = 1.54, p = 0.04), and springtime (odds ratio = 1.58, p = 0.02) were associated with flap misalignment. There was a significant difference in misalignment rates between surgeons (p = 0.02). This study found that larger treatment zones, higher operating room temperature, operating during the spring, and the use of Moria M2 microkeratome were associated with increased flap misalignment rates. The association with operating room temperature and seasonal variation is of interest and merits further research.

Nomogram to Predict Graft Thickness in Descemet Stripping Automated Endothelial Keratoplasty: An Eye Bank Study.

The purpose of this study was to develop a nomogram to predict postcut thickness of corneal grafts prepared at an eye bank for Descemet stripping automated endothelial keratoplasty (DSAEK). Retrospective chart review was performed of DSAEK graft preparations by 3 experienced technicians from April 2012 to May 2017 at the Eye Bank of Canada-Ontario Division. Variables collected included the following: donor demographics, death-to-preservation time, death-to-processing time, precut tissue thickness, postcut tissue thickness, microkeratome head size, endothelial cell count, cut technician, and rate of perforation. Linear regression models were generated for each microkeratome head size (300 and 350 μm). A total of 780 grafts were processed during the study period. Twelve preparation attempts resulted in perforation (1.5%) and were excluded. Mean precut tissue thickness was 510 ± 49 μm (range: 363-670 μm). Mean postcut tissue thickness was 114 ± 22 μm (range: 57-193 μm). Seventy-nine percent (608/768) of grafts were ≤130 μm. The linear regression models included precut thickness and donor age, which were able to predict the thickness to within 25 μm 80% of the time. We report a nomogram to predict thickness of DSAEK corneal grafts prepared in an eye bank setting, which was accurate to within 25 μm 80% of the time. Other eye banks could consider performing similar analyses.

Technique for Preparing Ultrathin and Nanothin Descemet Stripping Automated Endothelial Keratoplasty Tissue

To describe and report outcomes of our single-pass microkeratome technique for preparation of ultrathin (UT, ≤100 μm) and nanothin (NT, ≤50 μm) Descemet stripping automated endothelial keratoplasty (DSAEK) grafts. To prepare NT-DSAEK grafts, a pachymetry nomogram specific to each technician and individual microkeratome head was developed based on accumulated precut and postcut pachymetry data from previous DSAEK grafts. Mean graft thickness as well as precut and postcut endothelial cell counts (ECCs) of NT-DSAEK, UT-DSAEK, and Descemet membrane endothelial keratoplasty (DMEK) grafts between July 2015 and July 2017 were calculated and compared statistically. Endothelial cell loss was evaluated using calcein AM stains and ImageJ analysis. Postcut graft thickness and rates of perforation/tissue loss for NT-DSAEK grafts between May and July 2017 were calculated to determine overall graft preparation success rates. Mean postcut graft thickness for all grafts within the NT range was 41.0 ± 6.4 μm (range 26-50 μm). Mean ECC did not differ between NT-DSAEK, UT-DSAEK, and DMEK grafts (P = 0.759 and 0.633, respectively). The overall tissue loss rate from attempted NT-DSAEK was 4.8%. Excluding cases of perforation, the chance of achieving NT thickness was 60% and within the traditional UT range was 100%. We propose the term "NT-DSAEK" for grafts ≤50 μm. The described nomogram allows for standardized creation of NT grafts with a low tissue loss rate. This technique is safe and does not result in significant ECC loss compared with UT-DSAEK and DMEK grafts. Further studies are necessary to corroborate the postsurgical results of NT grafts.

Temporal and Spatial Flap Variability in Laser In-Situ Keratomileusis by Optical Coherence Tomography.

Purpose:To study changes in flap thickness made with two different microkeratome heads across different corneal locations using anterior segment optical coherence tomography (OCT).Methods:In this prospective, non-randomized, consecutive case series, subjects who had their laser in-situ keratomileusis (LASIK) flaps made using 90 μm (MSU90) or 130 μm (MSU130) disposable M2 microkeratome heads were examined using OCT. The measurements were performed at three locations (central and 2.5 mm to either side) at 1 day, 1 week, and 1 month postoperatively.Results:The central flap thickness was 123 ± 15, 130 ± 14, and 127 ± 13 μm, respectively, at 1 day, 1 week, and 1 month postoperatively in the MSU90 group (41 eyes) and 142 ± 20, 147 ± 19, and 143 ± 15 μm, respectively, in the MSU130 group (47 eyes). At 1 month, peripheral flap thickness was 161 ± 17 and 159 ± 13 μm, respectively, at 2.5 mm to the right and left of corneal center in the MSU90 group. The corresponding figures were 170 ± 14 and 167 ± 13 μm, respectively, in the MSU130 group. There was a statistically significant difference between the two groups at all locations (P < 0.001). No statistically significant change in flap thickness was detected in either group at any assessment time. There was a partial positive correlation (after controlling for preoperative manifest refractive spherical equivalent) between central flap thickness and preoperative ultrasound central pachymetry (r = 0.739, P = 0.036) in the MSU90 group but not in the MSU130 group.Conclusion:Using OCT, changes in flap thickness were minimal in the first month after LASIK. Flap thickness correlated strongly with central corneal thickness if a 90 μm head was used.

Preparation of ultrathin grafts for Descemet-stripping endothelial keratoplasty with a single microkeratome pass

We present a technique to achieve ultrathin Descemet-stripping automated endothelial keratoplasty (DSAEK). Using a simple method of controlling artificial anterior chamber pressure and drying the corneal surface, it was possible to thin the donor cornea at a rate of 11μm a minute. When the donor cornea was between 500μm and 510μm, a single pass was madeusinga 350μm microkeratomehead followed by a peripheral dissection. The resultingmean graft thickness was 83.2μm±14.9 (SD) (range 50 to 98μm) with a mean peripheral graft edge thickness of 106.8±10.9μm (range 90 to 120μm). There were no surgical complications, and all grafts remained attached. This is a reliable method for preparing ultrathin donor corneal lenticules for DSAEK in the operating room or eye bank without using multiple microkeratome heads or risking double passes.

Reproducibility of single-pass donor DSAEK tissue preparation with the MORIA single-use microkeratome

To assess the reproducibility of single-pass cutting for preparation of ultra-thin (≤120μm) donor cornea grafts in Descemet stripping automated endothelial keratoplasty (DSAEK). All consecutive patients of DSAEK performed using the MORIA One Use microkeratome (MORIA, Antony, France) in between June 2014 and August 2015. Patient and donor central corneal thickness (CTT), microkeratome head, remaining stromal bed thickness (RSBT), number of cut and graft thickness at 1 month and 6 months postoperatively were recorded in this single-center prospective study. The mean preoperative donor graft CCT was 569.0±45.1μm and the mean donor endothelial graft CCT immediately after the cut was 116.5±28.7μm. At 1 month postoperatively, the mean CCT was 102.8±35.9μm. At 6 months, the mean CCT was 89.4±26.2μm. In all eyes, the mean CCT decreased from the post-cut (116.5±28.7μm) to the last visit (89.4±26.2μm) (P<0.01) due to in vivo deturgesence of the graft. We obtained 77.5% ultra-thin DSAEK immediately after the cut, 77.5% at 1 month and 89.8% after 6 months. Single-pass technique with the MORIA One Use microkeratome offers safe and reproducible DSAEK tissue preparation and allows achieving ultra-thin DSAEK in 89.8% of cases.

Factors affecting laser in situ keratomileusis flap thickness: Comparison of 2 microkeratome heads

To identify the potential factors affect that affect the thickness of corneal flaps created using 2 different microkeratome heads. Care-Vision Laser Centers, Tel-Aviv, Israel. Retrospective comparative study. The study included eyes in which bilateral laser in situ keratomileusis (LASIK) was performed from January 1, 2005, to December 31, 2012, using an SBK-90 microkeratome head (Group 1) or an M2-90 microkeratome head (Group 2). Inclusion criteria were at least 18 years of age, a stable refraction for 12 months, an intraocular pressure of less than 21 mm Hg, and no history of autoimmune disease, diabetes, ocular surgery, or eye disease. In addition, patients had to cease wearing contact lenses for 2 weeks (rigid lenses) or 4 days (soft lenses) before the preoperative evaluation and before surgery. The disposable blade was used in the right eye first and then reused in the left eye. The study evaluated 6242 eyes of 3121 patients with a mean age of 32.2 years ± 9.8 (SD). Group 1 comprised 2560 eyes (41%), and Group 2 comprised 3682 eyes (59%). The eyes in Group 1 had thinner flaps (P < .001). The right eyes had thicker flaps (P < .001). Flap thickness had a positive correlation with precutting central corneal thickness (CCT) and operating room humidity and a negative correlation with patient age, preoperative sphere and cylinder, and operating room temperature. Statistically significant differences were found in flap thickness between surgeons (P < .001). Larger suction rings created thicker flaps (P < .001). Stepwise regression models accounted for up to 28.1% of the variation in flap thickness. Factors that were significantly correlated with flap thickness included the precutting CCT, whether the right or the left eye, the microkeratome head used, the surgeon performing the procedure, and the preoperative sphere. These findings might help prevent post-LASIK corneal ectasia. No author has a financial or proprietary interest in any material or method mentioned.

Thin lenticule Descemet's stripping automated endothelial keratoplasty: single, slow pass technique

To evaluate the outcomes of single pass thin lenticule sutureless Descemet's stripping automated endothelial keratoplasty with donor lenticules prepared using a 400 μm microkeratome head. Interventional case series. Cases with corneal endothelial dysfunction. Fifteen cases with corneal endothelial dysfunction (eight pseudophakic bullous keratopathy, three Fuchs' endothelial dystrophy, three congenital hereditary endothelial dystrophy and one failed graft) underwent thin lenticule Descemet's stripping automated endothelial keratoplasty at a tertiary care hospital. Donor lenticule was prepared with a single pass 400 μm Carriazo Barraquer microkeratome (Moria, Antony, France) head. Sutureless Descemet's stripping automated endothelial keratoplasty was performed in all the cases through a 3.5 mm corneoscleral tunnel using a Busin glide for graft insertion. Main parameters evaluated were postoperative donor lenticule thickness and best-corrected visual acuity. Donor lenticules were harvested successfully for all 15 cases without any complications. At 6-months follow up, the mean logMAR best-corrected visual acuity improved from 1.87 ± 0.52 to 0.109 ± 0.11 (P = < 0.0001). The mean donor lenticule thickness was 111 ± 17.62 μm (range 70-134 μm) at the last follow up. The mean endothelial cell loss was 26.33 ± 1.34%. Thin donor lenticules for Descemet's stripping automated endothelial keratoplasty can be safely harvested using a single pass technique with 400 μm microkeratome head and can be used for a successful Descemet's stripping automated endothelial keratoplasty surgery.

Preconditioned Donor Corneal Thickness for Microthin Endothelial Keratoplasty

To describe a novel surgical technique to produce thin endothelial grafts for Descemet stripping automated endothelial keratoplasty (DSAEK). Thirteen human cadaveric corneas in organ culture were randomized into conventional (n = 7) and microthin (n = 6) DSAEK groups. Grafts in the conventional DSAEK group were prepared using the conventional DSAEK technique of a single microkeratome pass with a 350-μm cutting head. Corneas in the microthin group were preconditioned to achieve a target central thickness of 530 μm before graft dissection with a 350-μm microkeratome head. Preconditioning involved stromal dehydration under pachymetric control using sterile airflow for 15-second increments. Donor and graft thicknesses were assessed with optical coherence tomography, and endothelial viability with trypan blue and alizarin red staining. Mean endothelial graft thickness obtained using the microthin DSAEK technique was 106 μm (SD, 32 μm) compared with 177 μm (SD, 33 μm) obtained using conventional DSAEK technique (P = 0.0024). Donor preconditioning yielded a predicted reduction of 100 μm in graft stromal thickness at a rate of 1.5 μm/s and mean duration of 72 seconds. The average anterior lamella thickness (cut depth) obtained in microthin and conventional DSAEK groups were 424 and 431 μm, respectively (P = 0.84). There was no difference in endothelial viability between the 2 groups. There were no corneal perforations during graft preparation in this study. Donor preconditioning by pachymetry-controlled stromal dehydration achieved significantly thinner endothelial grafts compared with the conventional DSAEK technique without compromise to endothelial viability or graft wastage.

Femtosecond laser and microkeratome-assisted Descemet stripping endothelial keratoplasty: first clinical results

AimTo perform Descemet stripping automated endothelial keratoplasty (DSAEK) using a novel technique to obtain very thin (<100 µm) posterior corneal disks.MethodsTwenty five DSAEK grafts were prepared with two sequential cuts:...

Combined Use of a Femtosecond Laser and a Microkeratome in Obtaining Thin Grafts for Descemet Stripping Automated Endothelial Keratoplasty: An Eye Bank Study

To evaluate the use of a femtosecond laser combined with a microkeratome in the preparation of posterior corneal disks for Descemet stripping automated endothelial keratoplasty (DSAEK). This experimental study involved ultrathin DSAEK tissue preparation of 22 donor corneas unsuitable for transplantation. The first cut was performed with an Intralase® FS60 laser and the second cut with a Moria CBm 300-µm microkeratome. The thickness of the first cut was modified for each cornea to obtain a final graft thickness of less than 110 µm. Precut and postcut central pachymetry were performed with an ultrasonic pachymeter. Central endothelial cell density (ECD) was calculated before and 24 hours after tissue preparation. Final graft thickness was 105.0 ± 26.1 (SD) µm (range 65-117). The mean microkeratome head cut thickness was 324.5 ± 10.9 µm (range 310-345). Precut and postcut ECDs averaged 2250 ± 222 and 2093 ± 286 cells/mm2, respectively, representing 6.9% of cell loss. No corneas were perforated. Femtosecond FS60 lasers and Moria CBm 300-µm microkeratomes can be used sequentially to prepare consistently thin DSAEK grafts with no irregular cuts or cornea perforations.

Microkeratome-Assisted Preparation of Ultrathin Grafts for Descemet Stripping Automated Endothelial Keratoplasty

To compare three microkeratome-assisted techniques for the preparation of ultrathin (UT) grafts for Descemet stripping automated endothelial keratoplasty. After dissection with a 300-μm microkeratome head in 40 donor tissues, a second cut was performed with a 130-μm head either after manual stromal hydration (group A, n = 10) or osmotic hydration at the eye bank (group B, n = 10) or with a 50- or 90-μm head, depending on residual bed thickness (group C, n = 10); no further dissection was performed in the control group (group D, n = 10). Corneal thickness and endothelial cell (EC) count were determined at all appropriate stages. Statistical analysis was performed using a Fisher exact test. Final graft thicknesses in groups A (89.1 ± 34.1μm), B (84.1 ± 18.6 μm), and C (72.1 ± 10.1 μm) were significantly lower than in group D (201.9 ± 25.3 μm) (P < 0.001). EC loss did not differ significantly among the groups. Multiple areas of Descemet detachment were seen in 4 of 10 corneas of group A. All methods proved equally efficient in producing UT grafts, but stromal hydration induced tissue structural changes. EC loss was unaffected by the additional manipulation required to prepare UT grafts.

Descemet Stripping Automated Endothelial Keratoplasty: Effect of Intraoperative Lenticule Thickness on Visual Outcome and Endothelial Cell Density

To determine the correlation between the intraoperative donor lenticule thickness in Descemet stripping automated endothelial keratoplasty (DSAEK) and both the best-corrected visual acuity (BCVA) and endothelial cell density (ECD) at 6 months. To describe relevant surgical considerations with regard to the choice of microkeratome head. Prospective case series. Thirty-five patients (37 eyes) undergoing DSAEK were included in this prospective case series. Intraoperative donor lenticule thickness, assessed by ultrasound pachymetry, was compared with BCVA and ECD 6 months postoperatively. Mean BCVA logarithm of the minimal angle of resolution (logMAR) was 0.58 preoperatively and 0.29 6 months postoperatively. Three eyes were excluded from BCVA analysis. The average donor lamellae thickness was 175 μm. Mean ECD loss was 39% 6 months postoperatively compared with that preoperatively. There was no correlation between donor lamella pachymetry and BCVA logMAR and ECD at 6 months in this series (P = 0.13 and P = 0.09, respectively). Analogous to our findings, a review of published reports on donor pachymetry in DSAEK did not provide data to suggest a correlation between donor corneal thickness and postoperative BCVA or ECD. Donor lenticule thickness does not have a direct effect on 6-month postoperative visual acuity or endothelial cells. Efforts should be made to reduce surgical trauma to the lenticule rather than adhering to a strict depth when cutting the graft. We propose using the Moria 350 μm microkeratome head for corneal thickness more than 600 μm and the 300 footplate for corneal thickness less than 600 μm.

Flap thickness variation with 3 types of microkeratome heads

To determine flap thickness variation with 3 types of microkeratome heads and identify the potential factors that affect flap thickness. Ruijin Hospital, Department of Ophthalmology, Shanghai, China. Comparative case series. Laser in situ keratomileusis was performed using the Moria microkeratome with the One Use-Plus SBK, M2 90, or M2 110 head. Flap thickness was calculated by subtraction pachymetry. Age, central corneal thickness (CCT), spherical equivalent refraction, mean keratometry, and horizontal corneal diameter were recorded preoperatively. The study comprised 180 eyes of 90 patients; 60 eyes were treated with each head. The difference in mean flap thickness between right and left eyes was not significant in the SBK group (97.50 μm ± 11.39 [SD] versus 96.73 ± 10.45 μm; P = .44) but was significant in the M2 90 group (128.03 ± 12.03 μm versus 123.40 ± 12.38 μm; P = .0071) and the M2 110 group (140.53 ± 15.14 μm versus 135.23 ± 18.03 μm, P = .0035). The difference from the intended flap thickness (right eyes and left eyes) was 2.50 ± 11.39 μm and 3.27 ± 10.45 μm, respectively, in the SBK group; -8.03 ± 12.03 μm and -3.40 ± 12.38 μm, respectively, in the M2 90 group; and -0.53 ± 15.14 μm and 4.77 ± 18.03 μm, respectively, in the M2 110 group. Flap thickness was positively correlated with baseline CCT in each group. Flap thickness was positively correlated with the preoperative CCT using the Moria microkeratome. The SBK head demonstrated the most accurate flap thickness, followed by the M290 head and the 110 head. No author has a financial or proprietary interest in any material or method mentioned.

Pneumatic Dissection and Storage of Donor Endothelial Tissue for Descemet's Membrane Endothelial Keratoplasty: A Novel Technique

To investigate the feasibility of pneumatic dissection of donor endothelium and the effect of 7 days of storage in tissue culture medium on the endothelial cell count. Experimental study. We used 20 human donor corneoscleral tissues deemed unsuitable for transplantation. Donor corneas were mounted on an artificial anterior chamber and the anterior stroma removed with a 300-micron microkeratome head. Air was injected into the residual donor tissue with a 30-G needle from the endothelial side to detach Descemet's membrane. The "bubble" was expanded as far as possible into the periphery. A silicone weight was attached to the scleral ring and the prepared tissue was stored in tissue culture medium for 7 days. Complete detachment of Descemet's membrane, size of detachment, pre- and post-storage endothelial cell counts. Complete detachment of Descemet's membrane was achieved in 19 of 20 (95%) cases. In 12 (60%) cases, this was achieved with a single injection; 7 (35%) cases required repeat injections. In 1 case, Descemet's membrane could not be detached despite repeat air injections. The average size of detachment was 8.11+/-2.0 mm. Endothelial cell loss after 7 days of tissue culture medium storage was 4.44+/-4.3%. Descemet's membrane and endothelium can be separated from the overlying stroma with a simple technique using air dissection. An adequate size of graft tissue is obtained without the need to manually handle the tissue. The technique allows storage of the tissue in tissue culture medium with low endothelial cell loss.

Repositioning free laser in situ keratomileusis flaps

We describe a protocol for adequate repositioning of free laser in situ keratomileusis (LASIK) corneal flaps created by a Moria M2 microkeratome even in the absence of fiduciary marks. In an enucleated porcine globe, a free flap was created by initially placing a longitudinal incision at the proposed hinge site followed by activating the forward pass of the automated microkeratome. A protocol was devised based on placement of a positioning dot on the free flap before the flap is retrieved from the microkeratome head. Preplaced surgical landmarks were used as a guide to determine the correct alignment of the free flap. Adequate orientation of the free flap to the stromal bed was achieved in 9 porcine eyes using the positioning dot method. The technique is applicable to the Moria M2 microkeratome only and must be validated for other types of keratomes.

Suture-Assisted vs Forceps-Assisted Insertion of the Donor Lenticula during Descemet Stripping Automated Endothelial Keratoplasty

To compare a new insertion method using a suture with the standard forceps-assisted insertion of the lamellar corneal graft in Descemet stripping automated endothelial keratoplasty (DSAEK). Interventional, comparative case series. DSAEK was performed on 28 consecutive eyes of 28 patients (mean age +/- standard deviation, 72.5 +/- 9.7 years; 12 males). The donor tissue was prepared using the Moria automated lamellar therapeutic keratectomy microkeratome head with a 300-mm blade depth on a Moria artificial anterior chamber (Moria, Antony, France). The central 9 mm of the recipient's Descemet membrane were stripped through a superior limbal incision. In eight consecutive unselected patients, a 10-0 monofilament suture on a long straight needle was used to insert the folded donor lenticula into the recipient's eye, whereas in the other 20 patients, a standard insertion forceps was used. During the suture insertion, an anterior chamber maintainer was used to fill the anterior chamber continuously with balanced salt solution to prevent its collapse. Suture-assisted DSAEK did not differ significantly from forceps-assisted DSAEK in any of the preoperative parameters. No significant differences were noted in the intraoperative or postoperative complications. Six months after surgery, there were no significant differences in endothelial cell counts (1804 vs 1935 cells/mm(2), respectively), visual acuity (20/40 vs 20/36, respectively), or refraction (spherical equivalent, 0.93 vs 1.05 diopters, respectively). Suture-assisted DSAEK is a valid alternative to forceps insertion; however, it does not seem to offer a significant advantage.