Deep Anterior Lamellar Keratoplasty Procedure Research Articles

Surgical Strategies to Manage Stromal Interface Irregularity Following Deep Anterior Lamellar Keratoplasty.

The purpose of this study was to describe the various surgical approaches to manage stromal interface irregularity following deep anterior lamellar keratoplasty (DALK). This interventional case series included patients requiring repeat keratoplasty procedures for stromal interface opacity and/or irregularity following DALK. The following surgical techniques with the aim of restoring transparency and regularity of the central optical zone and improving visual acuity in eyes that underwent unsuccessful DALK were performed: 1) simple anterior lamellar graft exchange, 2) repeat DALK with pneumatic dissection, 3) repeat DALK with deepening of manual lamellar dissection, 4) small diameter stripping of the central stroma-endothelium-Descemet complex and its replacement with a new endothelial lamella, and 5) 2-piece microkeratome-assisted mushroom penetrating keratoplasty. Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), slit-lamp examination, tonometry, and anterior corneal tomography were evaluated preoperatively, as well as 3, 6, and 12 months after surgery. Intraoperative and postoperative complications were recorded. Preoperative BCVA was less than 20/200 and improved to 20/40 or better in all cases, reaching 20/20 in 1 patient. Corneal clarity was restored in all eyes, and no recurrence of underlying disease was observed. No intraoperative or postoperative complications were reported. This case series describes several successful surgical approaches to improve the transparency and regularity of stromal interface obtained after a DALK procedure; the choice of the technique should be customized for the single eyes to still maintain the advantages of lamellar or minimally invasive grafts.

Design and Evaluation of an Eye Mountable AutoDALK Robot for Deep Anterior Lamellar Keratoplasty.

Partial-thickness corneal transplants using a deep anterior lamellar keratoplasty (DALK) approach has demonstrated better patient outcomes than a full-thickness cornea transplant. However, despite better clinical outcomes from the DALK procedure, adoption of the technique has been limited because the accurate insertion of the needle into the deep stroma remains technically challenging. In this work, we present a novel hands-free eye mountable robot for automatic needle placement in the cornea, AutoDALK, that has the potential to simplify this critical step in the DALK procedure. The system integrates dual light-weight linear piezo motors, an OCT A-scan distance sensor, and a vacuum trephine-inspired design to enable the safe, consistent, and controllable insertion of a needle into the cornea for the pneumodissection of the anterior cornea from the deep posterior cornea and Descemet's membrane. AutoDALK was designed with feedback from expert corneal surgeons and performance was evaluated by finite element analysis simulation, benchtop testing, and ex vivo experiments to demonstrate the feasibility of the system for clinical applications. The mean open-loop positional deviation was 9.39 µm, while the system repeatability and accuracy were 39.48 µm and 43.18 µm, respectively. The maximum combined thrust of the system was found to be 1.72 N, which exceeds the clinical penetration force of the cornea. In a head-to-head ex vivo comparison against an expert surgeon using a freehand approach, AutoDALK achieved more consistent needle depth, which resulted in fewer perforations of Descemet's membrane and significantly deeper pneumodissection of the stromal tissue. The results of this study indicate that robotic needle insertion has the potential to simplify the most challenging task of the DALK procedure, enable more consistent surgical outcomes for patients, and standardize partial-thickness corneal transplants as the gold standard of care if demonstrated to be more safe and more effective than penetrating keratoplasty.

Trends in keratoplasty from central and northern India. Part II: Types of keratoplasty.

To report the types of keratoplasty and analyze trends over a period of two decades in central and northern India. This was a retrospective review of eye bank registries of six tertiary eye care centers located in central and north India from 2005 to 2021. The indications and various keratoplasty procedures were compared between 2005-2012 and 2013-2021 to analyze the trend. A total of 13,223 corneal grafts were performed, of which therapeutic penetrating keratoplasty (TPK) (5719, 43.3%) was the most common procedure, followed by optical penetrating keratoplasty (OPK) (5528, 41.8%), Descemet stripping endothelial keratoplasty (DSEK) (1279, 9.7%), deep anterior lamellar keratoplasty (DALK) (376, 2.8%), Descemet membrane endothelial keratoplasty (DMEK) (215, 1.6%), patch grafts (75, 0.6%), and keratoprostheses (31, 0.2%). Overall, OPK procedures decreased (-14.1%, P < 0.001), but TPK (+3.1%, P < 0.019), DSEK (+7.1%, P < 0.001), and DMEK (+1.9%, P < 0.001) procedures increased. Although there was an increasing trend in the use of DALK (+0.8%, P < 0.083) and keratoprostheses (+0.3%, P = 0.074) procedures, the trends were not statistically significant. In keeping with worldwide trends, an increasing trend in lamellar keratoplasties was observed in central and northern India during the past decade. The trend was significant for DSEK. However, as corneal ulcers and scars were the major indications for keratoplasty, TPK and OPK remained the most common procedures.

Deep Anterior Lamellar Keratoplasty-Treated Keratoconic Eyes With Descemet Membrane Rupture.

The aim of this study was to evaluate the outcomes of deep anterior lamellar keratoplasty (DALK) and compare it with penetrating keratoplasty (PKP) in keratoconic eyes with Descemet membrane (DM) rupture. In this comparative retrospective case series, 33 keratoconic eyes with a history of hydrops underwent DALK and 27 received PKP. Baseline and postoperative visual acuity, corneal astigmatism, mean keratometry, endothelial cell density, and complication rates were measured. The median follow-up of patients who underwent DALK was 45 months (range, 4-76 months) and that of patients who underwent PKP was 84 months (range, 4-136 months). Both procedures had comparable postoperative visual acuity, astigmatism, and mean keratometry. Significantly higher endothelial cell densities were observed in DALK than in PKP at 2, 3, and 5 years postsurgery (2043 ± 767 vs. 1165 ± 683 cell/mm 2 , P = 0.007, n = 12 in both groups at 2 years). Intra-DALK, 15 perforations occurred (44.12%) and 1 (2.94%) was converted to PKP. Graft rejection was diagnosed in 1 (3.03%) DALK procedure versus 8 (29.63%) PKP ( P = 0.008), and other long-term complication rates were equivalent. Kaplan-Meier survival analysis also revealed a higher rejection-free survival rate for the DALK group ( P = 0.012). Subgroup analysis within both groups based on the severity of preoperative DM rupture revealed no significant difference in any major 2-year outcomes. DALK showed similar beneficial visual outcome and safety but significantly better endothelial protection over PKP in eyes with keratoconus and previous hydrops. Therefore, DALK is recommended in posthydrops cases irrespective of the DM rupture severity.

Triple Procedure: A Stepwise Combination of Deep Anterior Lamellar Keratoplasty and Cataract Surgery.

The aim of this study was to evaluate clinical outcomes of the combined surgery (triple procedure) of deep anterior lamellar keratoplasty (DALK), phacoemulsification, and intraocular lens (IOL) implantation using a new surgical strategy. The study included 43 eyes of 43 patients who underwent a triple procedure. Twenty-six eyes with good visibility through the cornea underwent phacoemulsification before the stromal dissection. Seventeen eyes with bad visibility underwent the DALK procedure first until achieving enough visibility to perform the lensectomy. IOL power calculation was performed for a postoperative estimated flat keratometry of 43.5 and aiming to avoid hyperopic postoperative refraction. The postoperative visual examination included uncorrected and corrected distance visual acuity (CDVA) measurements and manifest refraction. The mean follow-up time after suture removal was 3.06 ± 2.14 years. Mean CDVA significantly changed from 0.86 ± 0.56 logMAR preoperatively to 0.37 ± 0.28 logMAR in the last visit ( P < 0.0001). The percentage of eyes with CDVA ≤0.3 logMAR changed from 6.9% preoperatively to 62.8%. No eyes lost lines of vision after surgery, and 80% experienced an improvement of 2 or more lines. The safety index was 2.2. The mean postoperative refractive sphere was +0.13 ± 2.04 D, and the postoperative refractive cylinder was -4.02 ± 2.24 D. Only 2 cases (4.65%) obtained postoperative hyperopic astigmatism. No intraoperative complications were found. Combined surgery of DALK, phacoemulsification, and IOL implantation is an effective and safe procedure. Depending on the corneal transparency, different surgical strategies can be established to provide more efficacy and safety.

Update on Femtosecond Laser-Enabled Keratoplasty.

The application of femtosecond lasers to corneal transplantation is an intriguing proposition with many potential benefits to patients with various corneal diseases. The customized trephination pattern for donor and host matching offers many advantages regarding wound integrity and high precision of donor and recipient match at the interface, which should lead to faster healing and visual rehabilitation. Femtosecond laser-enabled keratoplasty (FLEK) is an advancement of conventional trephination penetrating keratoplasty, and in large clinical cohorts to date, there are meaningful improvements in visual outcomes and a lower risk of graft rejection. Femtosecond laser-enabled deep anterior lamellar keratoplasty (Femto-DALK) combines the advantage of a customized trephination pattern with the deep anterior lamellar keratoplasty procedure, which eliminates the risk of endothelial rejection. Furthermore, the precision of the femtosecond laser may offer additional novel approaches to lamellar keratoplasties. In time, advancements in femtosecond laser platforms will help cornea surgeons realize the added benefits and better optimize outcomes for patients, such that the cost-benefit calculus shifts toward wider accessibility for patients. Prospective randomized-controlled trials are needed to definitively determine the impact of femtosecond laser-enabled keratoplasties on long-term outcomes.

Refractive surgery after deep anterior lamellar keratoplasty: a review of the literature.

The main objective of this work is to present an updated review of the different surgical procedures for the correction of residual refractive errors following deep anterior lamellar keratoplasty (DALK) surgery. A review of the literature was conducted using PubMed, Web of Science, and Scopus databases. The search was conducted in January 2022 and was limited to articles published in peer-reviewed journals. The information extracted from each publication included sample size, mean follow-up time, pre- and post-operative uncorrected (UDVA) and corrected distance visual acuity (CDVA), pre- and post-operative refraction and spherical equivalent (SE), safety and efficacy indexes and complications. Residual ametropias, mainly high astigmatism and myopia, and the resulting anisometropia are likely to occur following DALK. They become a limiting factor and may lead to unsatisfactory visual restoration, therefore affecting patients' quality of vision and life. Alternative surgical interventions may be required to treat this residual ametropia, such as corneal refractive surgery or intraocular lens implantation. A total of 47 relevant articles were studied in detail. Different refractive surgery techniques have been shown to be effective and safe for the correction of ametropia following the DALK procedure and to improve the patient's quality of vision, although more research is needed to confirm long-term results. The final refractive technique will depend on different factors, such as the amount of ametropia, the condition of the cornea or the patient's individual needs, economics, and occupational demands.

Deep anterior lamellar keratoplasty versus penetrating keratoplasty in the treatment of stromal corneal dystrophies

AIM: To compare the efficacy and safety of penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) in the treatment of stromal corneal dystrophy. METHODS: A systematic review and Meta-analysis was conducted for studies comparing visual acuity [best-corrected visual acuity (BCVA) (LogMAR)] and corneal endothelial cell count (ECC) as well as safety outcomes of DALK and PK surgeries, including graft-related outcomes and intraoperative and postoperative complications. Embase, PubMed, and Google Scholar were searched for eligible studies until June 2019. Continuous and dichotomous variables were expressed as weighted mean difference (WMD) and risk ratios (RRs), respectively, along with their respective 95% confidence intervals (CIs). RESULTS: Five comparative studies recruiting 350 patients with macular and/or lattice corneal dystrophy (59.71% males) were eventually included. No significant differences were noted in the mean BCVA after both types of surgeries. However, following DALK procedures, corneal ECC was significantly higher two years postoperatively (WMD=401.62 cell/mm2, 95%CI: 285.39-517.85, P&lt;0.001), and graft and endothelial rejection rates were significantly lower (RR=0.30, 95%CI: 0.14-0.64, P=0.002; RR=0.09, 95%CI: 0.02-0.46, P=0.004, respectively) when compared to patients undergoing PK procedures. However, DALK procedures were associated with increased risks of intraoperative Descemet’s membrane perforations and postoperative double anterior chamber (All P&lt;0.001). CONCLUSION: DALK procedures are relatively more efficacious over the follow up periods with better safety outcomes than PK in patients with stromal CDs, conerning rejection and better visual outcome.

Preferred practice pattern and observed outcome of deep anterior lamellar keratoplasty - A survey of Indian corneal surgeons.

Purpose:This study aimed to assess the preferred surgical technique and outcome of deep anterior lamellar keratoplasty (DALK) among corneal surgeons in India.Methods:An online questionnaire-based cross-sectional survey was conducted among members of the Cornea Society of India (CSI) with experience of performing >10 DALK procedure. The responses pertaining to their surgical experience, preferred technique, complications, and outcome of DALK were collected and analyzed.Results:A total of 156 responses were received. In total, 35.9% of participants reported annual keratoplasty of >50, and DALK constituted >25% surgeries for 25% of participants. Ectatic corneal disorder was reported as the most common indication for DALK by 71.6% of the respondents. Big-bubble (BB) DALK (WA-1.82) was the most preferred technique, along with suction trephine (50%) for partial trephination and bottom port cannula (45.5%) for BB formation. On statistical analysis, no difference was observed in the surgeon reported success rate of BB formation with or without anterior lamellar keratectomy (ALK) (χ2 (1,156) = 3.1498, P = 0.08) or paracentesis (χ2 (1,156) = 0.2737, P = 0.60) before stromal air injection, and method of stromal air injection (χ2 (1,156) = 4.7325, P = 0.09). Conversion to penetrating keratoplasty was reported by 16% of participants in >25% cases, while 66.7% reported in <10% cases. Cataract and double anterior chamber were the most common complications. 50% of participants suggested that >20 procedures are required to overcome the learning curve.Conclusion:BB DALK is the most commonly practiced DALK technique, and its success is independent of ALK and paracentesis being performed prior to air injection and method of air injection (cannula/needle).

Microbial Keratitis in Corneal Transplants: A 12-Year Analysis.

PurposeTo investigate the frequencies, trends, and in vitro drug susceptibilities of the causative pathogens in corneal transplant microbial infections in Manchester Royal Eye Hospital.MethodsCorneal scrape results recorded by the microbiology service between 2004 and 2015 were extracted from an established database. This microbiological data was matched with a separate database of all corneal transplant procedures performed in our centre over this time period. Patient records were examined to collect specific patient data and to confirm the diagnosis of microbial keratitis.ResultsA total of 1508 grafts had been performed at our centre in this period. 72 episodes of graft microbial keratitis were identified from 66 eyes that had undergone keratoplasty procedures. Mean age was 56, and 51% of subjects were male. Ninety-three percent of microbial keratitis episodes occurred in penetrating keratoplasty procedures and 6% in deep anterior lamellar keratoplasty procedures. No endothelial grafts presented with infections throughout this time period. Of the 79 organisms identified, 73% were gram positive, 23% gram negative and 4% fungi. With regard to gram-positive organisms, vancomycin and gentamicin showed 100% and 91% susceptibility, respectively. Ofloxacin had a resistance rate of 13.7%. In terms of gram-negative organisms, gentamicin and chloramphenicol showed 100% sensitivity, with cefuroxime showing 69%. Resistance rates were less than 15% in all tested gram-negative antimicrobials.ConclusionThis paper describes the largest collection of corneal transplant infections identified within the UK. This finding may aid clinicians in predicting possible causative organisms for microbial keratitis and aid antibiotic choice.

Five-year Outcomes of Converted Mushroom Keratoplasty from Intended Deep Anterior Lamellar Keratoplasty (DALK) Mandate 9-mm Diameter DALK as the Optimal Approach to Keratoconus

To compare the 5-year outcomes of 9-mm-deep anterior lamellar keratoplasty (DALK) for keratoconus with those of conversions to mushroom keratoplasty (MK). Retrospective cohort study. The setting was the Ospedali Privati Villa Igea, Department of Ophthalmology, Forlì, Italy. The study population consisted of the medical records of all attempted DALK procedures (416 eyes) for the indication of keratoconus performed between January 2012 and January 2018; 68 eyes (16.4%) were converted to MK and analyzed as a separate cohort. The mean follow-up time was 33.8 ± 15.1months. Procedure(s) consisted of 9-mm DALK and MK (9-mm anterior lamella with 6-mm posterior lamella). Outcome measurements were best-corrected visual acuity (BCVA), refractive astigmatism, and endothelial cell loss (ECL) at 5 years. Average BCVA at 5 years was 0.06 ± 0.07 in the DALK group and 0.09 ± 0.15 in the MK group (P= .88). Refractive astigmatism following suture removal (all visits later than 12months) was slightly less in the DALK cohort (5-year DALK= 2.16 ± 1.40 diopter [D]; MK= 3.02 ± 0.89 D; P= .04; mean difference= 0.86 D [95% confidence interval [CI]: 0.71-1.01]). ECL was significantly higher in the MK group than in the DALK group at all follow-up intervals (5-year DALK= 19.36 ± 21.47%; MK= 56.61 ± 15.82%; P < .001). The total all-cause graft failure rate at 5 years was 0.58% for DALK (2 of 348) cases and 5.88% for MK (4 of 68) cases. Excellent 5-year visual and clinical outcomes associated with a 2-piece MK in cases converted from intended DALK mandate large-diameter DALK (9mm) as the optimal surgical approach to keratoconus.

Management of Descemet Membrane's Folds After Deep Anterior Lamellar Keratoplasty: Descemet Membrane-Tucking Technique.

To describe a surgical maneuver that allows for correction of central Descemet membrane (DM) folds at the end of a deep anterior lamellar keratoplasty (DALK) procedure. We term the present technique "DM tucking." A blunt tip spatula is introduced vertically into the trephination cut, 90 degrees away from the main direction of the DM folds, and advanced until it touches the host layer. Gentle pressure is applied, resulting in tucking of the redundant host layer toward the periphery. The tucking maneuver is repeated at different clock hours until a regular graft-host interface is obtained. We applied the present technique to several DALK procedures performed for keratoconus, and found it to be safe and effective. DALK is the procedure of choice for the surgical treatment of corneal stromal diseases with a healthy endothelium, such as keratoconus. DM folds are a possible complication after DALK in patients with advanced corneal ectasia, arising from the compression of the redundant host DM by the donor graft, once it is sutured to the recipient. DM folds after DALK, when they involve the visual axis, cause permanent visual disturbances DM tucking allows the displacement of the central DM folds toward the graft margin, where they do not affect the patient's quality of vision.

Outcomes of a Modified Technique for Successful Pneumatic Dissection in Pediatric Eyes With Corneal Scars.

To report the outcomes of a modified deep anterior lamellar keratoplasty (DALK) procedure for the treatment of scarred corneas in otherwise healthy pediatric eyes. All pediatric eyes undergoing DALK by the same surgeon (M.B.) between July 2013 and June 2017 were enrolled. The standard DALK procedure was modified by including a large (9 mm) and deep (150 μm from the thinnest pachymetric measurement) trephination, a minimal cannula advancement from the base of the trephination, and a clearing of a central 6 mm optical zone. The success rates of pneumatic dissection, visual and refractive outcomes, and complications were reported. A complete ophthalmologic examination was performed preoperatively and a few days after suture removal (6-months post-DALK) for all patients as well as 12, 24, and 36 months postoperatively for available patients. Fourteen eyes of 13 patients with various indications were included in this study. The mean age at the time of surgery was 11.7 ± 2.5 years. Pneumatic dissection succeeded in all but one case (13/14 eyes = 92.8%), which was completed by hand dissection. All sutures were removed within 6 months of surgery. With a minimum postoperative follow-up of 6 months, best spectacle-corrected visual acuity improved from ≤20/50 to ≥20/40 in all but one eye, which was known to be amblyopic. Despite impaired corneal transparency and increased tissue consistency, a modified DALK technique allows successful pneumatic dissection in an extremely high percentage of scarred pediatric eyes. Visual results compare favorably with those obtained in children after penetrating keratoplasty, while vision threatening complications are minimized.

Refractive outcome of keratoconus treated by big-bubble deep anterior lamellar keratoplasty in pediatric patients: two-year follow-up comparison between mechanical trephine and femtosecond laser assisted techniques

BackgroundTo evaluate refractive outcome 24 months after Deep Anterior Lamellar Keratoplasty (DALK) in pediatric patients by comparing results achieved using mechanical trephine and femtosecond laser.MethodsTwenty eyes of 20 patients affected by keratoconus were evaluated. To perform big-bubble DALK, 10 eyes (Group 1; mean age 11.2 ± 2.2 years) were subjected to the Hessburg-Barron mechanical trephine and the remaining 10 eyes (Group 2; mean age 11.3 ± 3.1 years) to a 150 kHz femtosecond laser that performed mushroom incisions. Preoperative thinnest point in the corneal thickness map and K readings were measured by the Sirius Scheimpflug camera. We also evaluated corrected distance visual acuity (CDVA) as logMAR value using spectacles, spherical equivalent and refractive astigmatism.ResultsMean preoperative thinnest point and pre- and post-operative K readings did not show significant difference (P > 0.05) between the two groups. CDVA, spherical equivalent and refractive astigmatism were respectively, 0.14 ± 0.08 logMAR and 0.13 ± 0.10 logMAR (P = 0.8), − 4.2 ± 1.1 D and − 2.8 ± 1.2 D (P = 0.03), 4.4 ± 2.0 D and 3.6 ± 1.2 D (P = 0.4) in Groups 1 and 2. All DALK procedures were uneventful.ConclusionOur findings suggest that femtosecond laser compared to mechanical trephine could significantly reduce the spherical equivalent amount in pediatric big-bubble DALK.

Graft survival rate of deep anterior lamellar keratoplasty for keratoconus: A meta-analysis.

Background:Deep anterior lamellar keratoplasty (DALK) is an optional treatment for patients with keratoconus, and the associated graft survival rate varies. Herein, we aimed to explore the graft survival rate of DALK in patients with keratoconus.Methods:PubMed, Web of Science, and ProQuest databases were searched to retrieve the related articles. General data, clinical characters, and graft survival rates were obtained directly from the included studies and analyzed by meta-analysis.Results:A total of 12 articles were included. The merged 1-, 3-, and 5-year graft survival rates were 100% (99.9–100%, P < .001), 92.9% (89.8–95.9%, P < .001), and 90.4% (86.0–0.948%, P < .001), respectively. Lower heterogeneity was shown in each subgroup that was divided neither according to the sample number nor number of surgeons.Conclusion:The survival rate slightly decreases year by year, but the overall trend seems relatively stable. Ensuring that all DALK procedures are performed by a single surgeon might be helpful to improve the graft survival rate after surgery.

New trends in corneal transplants at the University of Toronto

ObjectiveTo assess trends in surgical procedures and indications for all corneal transplants performed at the University of Toronto. DesignRetrospective cross-sectional study. ParticipantsOne thousand one hundred and four consecutive corneal transplants performed at the Kensington Eye Institute (KEI). MethodsDemographic, clinical, and pathological data retrieved from the Ophthalmic Pathology Laboratory on all corneal transplants performed at the KEI from January 2014 to December 2016. ResultsOver 3 years, partial-thickness lamellar keratoplasties were performed in 880 cases (80%) while full-thickness penetrating keratoplasties (PKP) accounted for 224 cases (20%). Leading causes of corneal transplant were Fuchs’ dystrophy (42%), graft failure (17%), bullous keratopathy (15%), and keratoconus (15%). Graft failure (40%) and keratoconus (31%) were the leading causes for PKP. Descemet’s membrane endothelial keratoplasty (DMEK) accounted for 37% of cases, Descemet’s stripping automated endothelial keratoplasty (DSAEK) for 30%, and deep anterior lamellar keratoplasty (DALK) for 13%. By 2016, partial-thickness procedures had increased by 10%, accounting for 85% of all procedures. In addition, DMEK increased by 26%, DSAEK decreased by 13%, and PKP decreased by 11%. Fuchs’ dystrophy remained the leading indication for DMEK (67%) and DSAEK (42%) procedures. In 2016, 73% of DALK procedures were for the treatment of keratoconus. ConclusionsPartial-thickness corneal transplants now account for 85% of all current graft procedures, and DMEK has emerged as the procedure of choice. Graft failure continues to be the leading indication for full-thickness grafts. Longitudinal studies are needed to determine whether these new trends persist and their future impact on graft failures.

Use of a handheld slit beam intraoperatively to assist in big bubble formation during deep anterior lamellar keratoplasty

Deep anterior lamellar keratoplasty (DALK) is preferred over conventional penetrating keratoplasty (PKP) for the treatment of anterior corneal opacities or ectasias due to decreased risk of endothelial rejection. However, DALK remains surgically challenging, largely due to challenges associated with achieving consistent pneumo-dissection of posterior stroma from the underlying pre-Descemet’s or Descemet’s membrane (DM). Air must be injected at sufficient depth in the corneal stroma in order to achieve successful pneumo-dissection, but advancing a needle too deep into the cornea can lead to perforation of DM. We describe here a novel technique using a handheld slit lamp (Eidolon model 510L, Eidolon Optical LLC, Natick, MA, USA) to assist in creation of the big-bubble in DALK surgery. Use of a handheld slit beam intraoperatively is a safe, relatively inexpensive, and effective technique for increasing the success of big-bubble formation in DALK procedures.

Comparaison des résultats anatomiques et fonctionnels à 12 mois d’une série de kératoplasties lamellaires profondes assistées au laser femtoseconde Z6 versus trépanation manuelle pour kératocônes sévères

The management of severe keratoconus requires corneal transplantation, for which the gold standard is deep anterior lamellar keratoplasty (DALK), preserving the healthy Descemet's membrane and endothelium. The safety and reproducibility of corneal cuts have been improved by the evolution of femtosecond lasers in refractive surgery, and femtosecond laser in DALK would seem to provide the same advantages over the manual method. In our retrospective study, we compare functional and anatomical results of femtosecond assisted DALK versus manual trephination DALK in patients with keratoconus in stage 4of the Krumeich classification. It is a retrospective study including all patients with stage 4keratoconus who underwent femtosecond laser assisted DALK between November 2012and November 2015in Nantes hospital. We compared those patients to a group of patients who underwent manual DALK in the same period, paired by age and maximal keratometry. We assessed visual acuity, pachymetry, endothelial cell density (specular microscopy), and keratometry before surgery and at 4, 8and 12months of follow-up. Laser settings and intraoperative complications were recorded. Nineteen patients underwent surgery by femtosecond assisted DALK, 6women and 12men with average age 30.2±10.8years at transplantation. They were paired with a group of 17patients who underwent manual DALK in order to compare results. Before surgery, mean visual acuity in the femtosecond group was 0.90logMAR versus 0.89logMAR in the manual group, showing no statistically significant difference (P=0.96). Both groups were similar in terms of preoperative age, mean keratometry, pachymetry and endothelial cell density. Average visual acuity post-surgery was 0.27, 0.26; and 0.14logMAR for femtosecond DALK versus 0.27, 0.17et 0.25for manual DALK at 4, 8and 12months follow-up, respectively showing no statistically significant difference. After surgery, at 4, 8and 12months, mean pachymetry was similar in both groups, and average endothelial cell density was 2390cells/mm2in femtoDALK versus 2531cells/mm2in manual DALK at 12months of follow-up, showing no statistically significant difference (P=0.5726). The rate of Descemet's membrane microperforations during the procedure was low and similar for both groups. Our study allows for a 12month follow-up, with assessment of visual recovery, anatomical result and endothelial safety in a sample of 19femtosecond laser assisted DALK with no statistical significant difference versus the manual trephination group. Femtosecond laser allows for increased reproducibility of the DALK procedure without reducing adverse effects during surgery. Femtosecond laser seems to improve the technique of the DALK procedure, and future developments could improve the reproducibility of DALK even further. A medical economics study would be necessary to determine the cost effectiveness of femtosecond laser assisted DALK.

Comparison of 12-month anatomic and functional results between Z6 femtosecond laser-assisted and manual trephination in deep anterior lamellar keratoplasty for advanced keratoconus

The management of severe keratoconus requires corneal transplantation, for which the gold standard is deep anterior lamellar keratoplasty (DALK), preserving the healthy Descemet's membrane and endothelium. The safety and reproducibility of corneal cuts have been improved by the evolution of femtosecond lasers in refractive surgery, and femtosecond laser in DALK would seem to provide the same advantages over the manual method. In our retrospective study, we compare functional and anatomical results of femtosecond-assisted DALK versus manual trephination DALK in patients with keratoconus in stage 4 of the Krumeich classification. It is a retrospective study including all patients with stage 4 keratoconus who underwent femtosecond laser-assisted DALK between November 2012 and November 2015 in Nantes university medical center. We compared those patients to a group of patients who underwent manual DALK in the same period, paired by age and maximal keratometry. We assessed visual acuity, pachymetry, endothelial cell density (specular microscopy), and keratometry before surgery and at 4, 8 and 12months of follow-up. Laser settings and intraoperative complications were recorded. Nineteen patients underwent surgery by femtosecond-assisted DALK, 6women and 12men with average age 30.2±10.8years at transplantation. They were paired with a group of 17patients who underwent manual DALK in order to compare results. Before surgery, mean visual acuity in the femtosecond group was 0.90logMAR versus 0.89logMAR in the manual group, showing no statistically significant difference (P=0.96). Both groups were similar in terms of preoperative age, mean keratometry, pachymetry and endothelial cell density. Average visual acuity post-surgery was 0.27; 0.26; and 0.14logMAR for femtosecond DALK versus 0.27; 0.17et 0.25 for manual DALK at 4, 8 and 12months follow-up respectively, showing no statistically significant difference. After surgery, at 4, 8 and 12months, mean pachymetry was similar in both groups, and average endothelial cell density was 2390cells/mm2 for femto DALK versus 2531cells/mm2 for manual DALK at 12months of follow-up, showing no statistically significant difference (P=0.5726). The rate of Descemet's membrane microperforations during the procedure was low and similar for both groups. Our study allows for a 12-month follow-up, with assessment of visual recovery, anatomic result and endothelial safety in a series of 19femtosecond laser-assisted DALK with no statistical significant difference versus the manual trephination group. Femtosecond laser allows for increased reproducibility of the DALK procedure without reducing adverse effects during surgery. Femtosecond laser seems to improve the technique of the DALK procedure, and future developments could improve the reproducibility of DALK even further. A medical economics study would be necessary to determine the cost-effectiveness of femtosecond laser-assisted DALK.

Immunologic Rejection Episodes After Deep Anterior Lamellar Keratoplasty: Incidence and Risk Factors.

To assess the rejection episode rate after deep anterior lamellar keratoplasty (DALK) and to identify associated risk factors. This retrospective review of 251 primary DALK procedures performed by 14 surgeons at a single center between February 2008 and November 2015 evaluated the rejection episode rate and associated risk factors using Kaplan-Meier survival and proportional hazards analyses, which took the length of follow-up into consideration. Transplant indications were keratoconus or ectasia after laser refractive surgery (n = 170, 68%), corneal opacity (n = 72, 28%), and other anterior corneal disease (n = 9, 4%). The median recipient age was 46 years. The overall rejection episode rate was 14% with 18-month median follow-up and a 7-week median postoperative corticosteroid duration. In univariate analysis, increased risk of rejection episodes was associated with younger recipient age [relative risk (RR): 2.1, 95% confidence interval (CI): 1.4-5.2], African American race (RR: 2.1, 95% CI: 1.1-4.1), and use of manual trephination (compared with the femtosecond laser) for the side-cut incisions (RR: 2.7, 95% CI: 1.4-5.2). In multivariate analysis, the combined effect of patient age and race (P = 0.0012) and the side-cut method (P = 0.021) were each significant risk factors. This study demonstrates the substantial rate of rejection episodes that can be induced by corneal stroma in DALK and suggests that postoperative topical corticosteroids should be continued longer than the study's 7-week median and that young African Americans need higher-dose, longer-duration topical corticosteroids. The association between the side-cut method and rejection risk merits further investigation.