Deep anterior lamellar keratoplasty as an alternative to penetrating keratoplasty a report by the american academy of ophthalmology. Ophthalmology. 2011;118:209-218. [PMID: 21199711 DOI: 10.1016/j.ophtha.2010.11.002]

A Novel Wax Based Piezo Actuator for Autonomous Deep Anterior Lamellar Keratoplasty (Piezo-DALK)

This paper reports the design and evaluation of a novel piezo based actuator for needle drive in autonomous Deep Anterior Lamellar Keratoplasty (piezo-DALK). The actuator weighs less than 8g and is 20mm × 20mm × 10.5mm in size, making it ideal for eye-mounted applications. Mean open loop positional deviation was 1.17 ± 3.15um, and system repeatability and accuracy were 17.16um and 18.33um, respectively. Stall force was found to vary linearly with the cooling cycle and the actuator achieved a maximum drive force of 3.98N. When simulating the DALK procedure in synthetic corneal tissue, the piezo-DALK achieved a penetration depth of 643.56um which was equivalent to 92.1% of the total corneal thickness. This correlated closely with our desired depth of 90% ± 5% and took 2.5 hours to achieve. This work represents the first eye mountable actuator capable of "Big Bubble" needle drive for autonomous DALK procedures.

Management of Corneal Clouding in Patients with Mucopolysaccharidosis

Mucopolysaccharidoses (MPS) are a rare group of lysosomal storage disorders characterized by the accumulation of incompletely degraded glycosaminoglycans (GAGs) in multiple organ systems including the eye. Visual loss occurs in MPS predominantly due to corneal clouding and retinopathy, but the sclera, trabecular meshwork and optic nerve may all be affected. Despite the success of therapies such as enzyme replacement therapy (ERT) and hematopoietic stem-cell transplantation (HSCT) in improving many of the systemic manifestations of MPS, their effect on corneal clouding is minimal. The only current definitive treatment for corneal clouding is corneal transplantation, usually in the form of a penetrating keratoplasty or a deep anterior lamellar keratoplasty. This article aims to provide an overview of corneal clouding, its current clinical and surgical management, and significant research progress.

Post-keratoplasty Infectious Keratitis: Epidemiology, Risk Factors, Management, and Outcomes

Post-keratoplasty infectious keratitis (PKIK) represents a unique clinical entity that often poses significant diagnostic and therapeutic challenges. It carries a high risk of serious complications such as graft rejection and failure, and less commonly endophthalmitis. Topical corticosteroids are often required to reduce the risk of graft rejection but their use in PKIK may act as a double-edged sword, particularly in fungal infection. The increased uptake in lamellar keratoplasty in the recent years has also led to complications such as graft-host interface infectious keratitis (IIK), which is particularly difficult to manage. The reported incidence of PKIK differs considerably across different countries, with a higher incidence observed in developing countries (9.2-11.9%) than developed countries (0.02-7.9%). Common risk factors for PKIK include the use of topical corticosteroids, suture-related problems, ocular surface diseases and previous corneal infection. PKIK after penetrating keratoplasty or (deep) anterior lamellar keratoplasty is most commonly caused by ocular surface commensals, particularly Gramme-positive bacteria, whereas PKIK after endothelial keratoplasty is usually caused by Candida spp. Empirical broad-spectrum antimicrobial treatment is the mainstay of treatment for both PKIK, though surgical interventions are required in medically refractory cases (during the acute phase) and those affected by visually significant scarring (during the late phase). In this paper, we aim to provide a comprehensive overview on PKIK, encompassing the epidemiology, risk factors, causes, management and outcomes, and to propose a treatment algorithm for systematically managing this challenging condition.

Prospective Clinical Study of Keratoconus Progression in Patients Awaiting Corneal Cross-linking

PURPOSE

Keratoconus progression should be treated with corneal cross-linking (CXL) in a timely manner. This study aimed to investigate patient factors associated with keratoconus progression between time of listing and at time of CXL.

METHODS

Prospective observational study at a tertiary center. Ninety-six eyes of 96 patients with keratoconus. Demographic, clinical, and tomographic parameters were analyzed to determine the risk factors for keratoconus progression. Analyzed tomographic indices included steepest keratometry, average keratometry, cornea thinnest point, index of surface variance, index of vertical asymmetry, keratoconus index, center keratoconus index, index of height asymmetry, and index of height decentration.

RESULTS

A total of 38 eyes (39.6%) were found to have keratoconus progression during an average waiting time of 153 ± 101 days. There were significant differences in preoperative tomographic parameters such as index of surface variance (111.3 ± 36.6 vs. 88.3 ± 31.8; P = 0.002), index of vertical asymmetry (1.1 ± 0.4 vs. 0.9 ± 0.4; P = 0.005), keratoconus index (1.31 ± 0.12 vs. 1.22 ± 0.11; P < 0.001), and index of height decentration (0.16 ± 0.07 vs. 0.11 ± 0.06; P = 0.015) between eyes that progressed and those that remained stable. There were no significant differences in steepest keratometry, average keratometry, cornea thinnest point, and center keratoconus index. Multivariate analysis did not reveal age, presence of atopy/atopic keratoconjunctivitis, eye rubbing, or waiting time to be a significant risk factor for progression; however, Maori ethnicity was a risk factor (odds ratio = 3.89; P = 0.02).

CONCLUSIONS

A significant proportion of eyes were found to be progressing while waiting for CXL. A risk stratification score for patients awaiting CXL may reduce the risk of progression.

Practice patterns of corneal transplantation in Europe: first report by the European Cornea and Cell Transplantation Registry

PURPOSE

To report practice patterns of corneal transplantation in Europe.

SETTING

Corneal clinics in 10 European member states (MS), the United Kingdom, and Switzerland.

DESIGN

Multinational registry study.

METHODS

Corneal transplant procedures registered in the European Cornea and Cell Transplantation Registry were identified. Preoperative donor and recipient characteristics, indication and reason for transplantation, and surgical techniques were analyzed.

RESULTS

A total of 12 913 corneal transplants were identified from 10 European Union MS, the United Kingdom, and Switzerland. Most countries were self-sufficient with regard to donor tissue. Fuchs endothelial corneal dystrophy was the most common indication (41%, n = 5325), followed by regraft (16%, n = 2108), pseudophakic bullous keratopathy (12%, n = 1594), and keratoconus (12%, n = 1506). Descemet stripping automated endothelial keratoplasty (DSAEK, 46%, n = 5918) was the most commonly performed technique, followed by penetrating keratoplasty (30%, n = 3886) and Descemet membrane endothelial keratoplasty (9%, n = 1838). Vision improvement was the main reason for corneal transplantation (90%, n = 11 591). Surgical technique and reason for transplantation differed between indications.

CONCLUSIONS

This report provides the most comprehensive overview of corneal transplantation practice patterns in Europe to date. Fuchs endothelial dystrophy is the most common indication, vision improvement the leading reason, and DSAEK the predominant technique for corneal transplantation.

Comparison of complications and visual outcomes between big-bubble deep anterior lamellar keratoplasty and penetrating keratoplasty for fungal keratitis

BACKGROUND

To compare the postoperative complications and visual outcomes of big-bubble deep anterior lamellar keratoplasty (BB-DALK) and penetrating keratoplasty (PK) for fungal keratitis (FK).

METHODS

This retrospective study included 94 cases of BB-DALK for FK and 161 cases of PK for FK from a tertiary ophthalmology care centre.

RESULTS

The most common FK pathogens were Fusarium (n = 84, 32.9%) and Aspergillus (n = 67, 26.3%). The recurrence rates after BB-DALK and PK were 3.2 and 5%, respectively (p = 0.723). The follow-up duration was 31.9 ± 15.8 months in the BB-DALK group and 33.9 ± 15.0 months in the PK group. The immune rejection rate was significantly lower in the BB-DALK group than in the PK group (1.1 vs. 18.6%, p < 0.001), as was the incidence of secondary glaucoma (p = 0.018). Endothelial cell density in the BB-DALK group tended to be stable at postoperative month 6, whereas the PK group still attenuated at a hyper-physiological rate. Postoperative best-corrected visual acuity (BCVA) significantly improved in both groups (p < 0.001). No significant difference between-group was observed in BCVA, refractive cylinder, and spherical equivalent postoperatively.

CONCLUSION

Big-bubble DALK is a useful and safe alternative to PK for medically uncontrolled FK.

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).

Acute interface infectious keratitis with multidrug resistant Klebsiella and Escherichia Coli following deep anterior lamellar keratoplasty

Acute interface infectious keratitis (AIIK) is a rare and devastating complication following lamellar keratoplasty. Here, we report a case of AIIK following deep anterior lamellar keratoplasty (DALK) caused by double gram-negative bacilli and required urgent therapeutic penetrating keratoplasty (TPK). Microbiology revealed co-infection with Klebsiella and E. Coli sensitive only to colistin. Donor rim culture also grew Klebsiella. TPK was successful in controlling the infection and the patient responded to topical fortified amikacin and ciprofloxacin. Since optical quality tissue was used, the patient regained 20/40 vision postoperatively. This report highlights that immediate TPK and intense antimicrobial therapy can salvage these eyes with good visual outcome.

Corneal neovascularisation following deep anterior lamellar keratoplasty for corneal ectasia: incidence, timing and risk factors

BACKGROUND

The purpose of this study was to evaluate the incidence, timing and risk factors of corneal neovascularisation (NV) after deep anterior lamellar keratoplasty (DALK) for corneal ectasia.

METHODS

This study included 616 eyes who underwent DALK between 2012 and 2020 in two tertiary referral centres. In one centre topical corticosteroids were discontinued after complete suture removal 1 year after surgery, whereas in the other they were discontinued 3-4 months after surgery. The presence and severity of corneal NV was ascertained based on slit lamp photographs. Potential risk factors for corneal NV were evaluated using the Cox proportional hazards model.

RESULTS

The cumulative incidence of corneal NV was 8.7% at 1 year after surgery and 13.2% at 5 years. Mean time interval from surgery to development of corneal NV was 12.8±16.2 months, with 68.9% of cases occurring before complete suture removal. Early discontinuation of topical steroids, older age and ocular allergy were associated with an increased risk of developing corneal NV (respectively, HR=2.625, HR=1.019, HR=3.726, all p<0.05).

CONCLUSIONS

The risk of corneal NV is higher in the first year following DALK. Early discontinuation of topical steroids, ocular allergy and older age are significant predictors of corneal NV.

Deep anterior lamellar keratoplasty for corneal penetrating wounds

PURPOSE

To report our surgical experience of deep anterior lamellar keratoplasty (DALK) performed in eyes with scarring resulting from a corneal penetrating wound without tissue loss.

METHODS

Case series of three eyes of three patients that underwent DALK for poor vision due to a scar resulting from a previous corneal penetrating wound. Surgery was performed at least 1 year after the initial injury. Manual dissection technique was used in all cases. Preoperative and postoperative best correct visual acuity (BCVA), postoperative residual bed thickness, and postoperative endothelial cell count (ECC) were evaluated.

RESULTS

Preoperative BCVA ranged from 1.3 to 1.0 LogMAR. Two eyes were pseudophakic and one eye had a traumatic cataract. Manual DALK was successfully accomplished in all three cases. The mean residual recipient bed thickness was 103 µm (range 68-130 µm). The mean endothelial cell loss at the 6th month of follow-up was 6% (range 3%-11%) with a further 1% decrease at 4 years. One of the patients underwent cataract surgery and limbal relaxing incisions 1 year after DALK having a total endothelial cell loss of 4.8% at 2 years of follow-up. BCVA at 2 years of follow-up was 0.1 LogMAR (range 0.22-0.0 LogMAR). No episode of rejection was recorded, and all grafts remained clear at last follow-up (5 years, range 4-6 years).

CONCLUSIONS

Manual DALK should be considered in cases of corneal scars in optical zone resulting from penetrating wound.

Manual DALK in Keratoconus: An Ex Vivo Light and Transmission Electron Microscopy Analysis 2 Years After Surgery

PURPOSE

The aim of this study was to evaluate the microscopic structure of a human cornea 2 years after manual deep anterior lamellar keratoplasty (DALK) for keratoconus with a recipient residual stromal bed thickness of 100 μm, using light and transmission electron microscopy.

METHODS

A human cornea treated with manual DALK for keratoconus 2 years before was removed during penetrating keratoplasty because of stromal opacity of unknown origin, involving about half of the sample. The transparent half of the specimen was processed for light and transmission electron microscopy.

RESULTS

Light microscopy examination performed with different staining techniques (hematoxylin and eosin, Picrosirius red, and Masson trichrome) revealed a homogeneous stroma. No interface was detected. Electron microscopy confirmed these findings.

CONCLUSIONS

This study confirmed the available clinical and confocal studies that show progressive stromal remodeling after manual DALK. Two years after surgery, no posterior stromal interface was detected.

Comparative Study of Long-term Graft Survival Between Penetrating Keratoplasty and Deep Anterior Lamellar Keratoplasty

PURPOSE

Endothelial failure and immunological graft rejection remain long-term complications leading to late graft failure in penetrating keratoplasty (PK). Deep anterior lamellar keratoplasty (DALK) has emerged as a viable alternative that enables preservation of the host's endothelial cells to eliminate risks of endothelial rejection and failure. The aim of this study was to compare long-term graft survival between PK and DALK.

DESIGN

Retrospective clinical cohort study.

METHODS

All consecutive primary grafts of DALKs (n = 362) and PKs (n = 307) performed for optical indications in a tertiary eye center from the ongoing, prospective Singapore Corneal Transplant Study. Ten-year graft survival outcomes were compared. Cases in which endothelial pathologies were diagnosed were excluded, as DALK was not performed for such cases. Main outcome measurements were mean graft survival rate.

RESULTS

The survival rate for PK was 94.4%, 80.4%, and 72.0% at 1, 5, and 10 years, respectively; and 95.8%, 93.9%, and 93.9% at 1, 5, and 10 years, respectively, for DALK (P = .001). Patients who underwent PK developed more complications of glaucoma (29.3% vs. 11.6%, respectively; P < .001), allograft rejection (16.6% vs. 1.7%, respectively; P < .001), epithelial problems (10.4% vs. 5.5%, respectively; P = .018), and nonimmunological failure (7.8% vs. 1.9%, respectively; P < .001), compared to DALK. Rates of graft failure attributable to rejection (36.7% vs. 5.9%, respectively; P = .015) and endothelial failure (36.7% vs. 5.9%, respectively; P = .015) were lower in DALK.

CONCLUSIONS

The 10-year graft survival for primary DALK was superior to that for PK for corneal pathologies with functional endothelium. Primary DALK resulted in fewer post-operative complications and lower rates of graft rejection and failure. This study strengthens the case in favor of performing DALK over PK when possible.

Indications of Keratoplasty and Outcomes of Deep Anterior Lamellar Keratoplasty Compared to Penetrating Keratoplasty

Background

Corneal diseases are a significant cause of visual impairment and blindness. Despite the treatable nature of many corneal diseases before visual demise, many cases of advanced disease necessitating keratoplasty for visual rehabilitation are encountered. A mismatch between the number of corneal donors and potential recipients also exists worldwide, with underutilization of certain types of keratoplasty techniques that may allow more efficient use of this limited resource.

Methodology

A retrospective cohort study of all cases of optical corneal transplantations performed from January 1, 2015 to October 31, 2020 was performed. Indications for keratoplasty, type of keratoplasty, complications, intraocular pressure elevation, and best corrected visual acuity (BCVA) by category and range at different time intervals were collected and analyzed. Findings were compared between penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) for all indications, specifically for keratoconus (KCN).

Results

A total of 58 corneal transplants meeting our criteria were performed during the study period. PK was performed for 29 eyes, DALK for 28 eyes, and endothelial keratoplasty for one eye. The most frequently encountered indication was KCN (62.1%). The number of eyes with BCVA of 20/100 or better increased from preoperative BCVA, 37/58 eyes had BCVA worse than 20/100 before keratoplasty (63.8%), while at the time of last follow-up 45/58 eyes had BCVA of 20/100 or better (77.6%). At the time of last follow-up 16/58 had BCVA in the range of 20/20 to 20/40 (27.6%) and 29/58 eyes had BCVA in the range of 20/50 to 20/100 (50%). Comparison of all cases of PK to DALK for all indications showed significantly better BCVA by category at one year, at last follow-up, and BCVA range at last follow-up (p = 0.032, 0.001, and 0.014, respectively). Although better visual acuity results by category and range at one year and last follow-up, respectively, were observed in more patients undergoing DALK than PK, for KCN the results were not statistically significant (p = 1.00, 1.00, 0.417, and 0.374, respectively). Overall, 70% of recorded complications, intraocular pressure (IOP) elevations, and graft rejections were seen in eyes that underwent PK; however, these findings were not statistically significant (p = 0.297). Graft failures occurred more frequently with PK than deep anterior keratoplasty when analyzed for all indications of keratoplasty (p = 0.010).

Conclusions

Despite advancement and improvements in surgical techniques, statistics continue to show underutilization of the invaluable resource of donor corneas, with PK still being performed more than DALK for diseases that do not affect the endothelium. Our study found superior visual acuity outcomes of DALK as well as the advantages of less frequent complications, IOP elevations, graft rejections, and graft failures. We encourage ophthalmologists to utilize DALK in appropriate candidates to more fully utilize the scarce and potentially vision-restoring resource of donor corneal tissue.

Femtosecond Laser-Assisted Big-Bubble Deep Anterior Lamellar Keratoplasty

Purpose

To determine whether type 1 big-bubble (BB) formation is influenced by the sequence of incisions created with the Victus femtosecond laser (FSL) enabled with software version 3.4 (SV 3.4) during deep anterior lamellar keratoplasty (DALK).

Materials and Methods

Consecutive FSL-assisted DALK BB procedures were performed on 20 human donor corneas: 10 shaped by tunnel incision followed by lamellar incision (tunnel-lamellar group, TL) and 10 in the reverse order (lamellar-tunnel group, LT). The BB type was assessed by evaluating dynamic air movement during air inflation; bubble diameter and floor thickness were measured by anterior segment optical coherence tomography.

Results

Overall, a type 1 BB formed in 85% of eyes: 100% in the TL group and 70% in the LT group. In the LT group, a type 2 BB formed in 2 corneas and one cornea was perforated during cannula insertion. Type 1 BB was achieved after one attempt in 90% of eyes in the TL group and in 57% in the LT group.

Conclusion

Shaping the tunnel before rather than after lamellar incision may be more effective for obtaining a type 1 BB by air injection.

Femtosecond laser-assisted implantation of corneal stroma lenticule for keratoconus

Purpose

To review recent progress, challenges, and future perspectives of stromal keratophakia for the treatment of advanced keratoconus.

Methods

We systematically reviewed the literature in the PubMed database, last update June 30, 2020. No language restriction was applied. The authors checked the reference lists of the retrieved articles to identify any additional study of interest.

Results

Several techniques have been proposed for the treatment of keratoconus in order to avoid or delay keratoplasty. This was primarily due to the lack of accessibility to donor corneas in many countries. The ease and predictability of the more advanced femtosecond lasers used to correct ametropias by stromal lenticule extraction lead to hypothesize that generated refractive lenticules could be implanted into corneal stromal layers to restore volume and alter the refractive properties of the cornea in patients with corneal ectasias. At the same time, new techniques for preservation, customization, and cellular therapy of the corneal stromal have been developed, directing to the valorization of otherwise discarded byproducts such as donor corneas unsuitable for either lamellar of penetrating keratoplasty.

Conclusions

Femtosecond laser-assisted stromal keratophakia could be a suitable therapeutic option for the treatment of corneal ectasias, especially in patients with advanced keratoconus, providing biomechanical support recovering the pachimetry to nearly normal value at the same time. The accuracy and predictability of the refractive outcome are yet a critical issue and the patient eligible for the procedure still has to be characterized.

[Excimer laser in keratoconus management]

Visual rehabilitation in keratoconus is a challenge, notably because of the significant irregular astigmatism and optical aberrations that it induces. Many surgical techniques have been developed in addition to, or in the case of failure of, spectacles and rigid gas permeable contact lenses: intracorneal ring segments, intraocular lenses, excimer laser and, as a last resort, keratoplasty. Excimer laser photoablates the cornea, allowing remodeling of its surface. There are various treatment modes (wavefront-optimized, wavefront-guided and topography-guided), allowing performance of a customized treatment if needed. Its use in keratoconus has been described since the 2000s, alone or in combination with other procedures. For example, the combination of photoablation and corneal cross linking, a technique that increases corneal rigidity and in so doing can slow or even stop the progression of keratoconus, proved its efficacy and safety in many studies, and various protocols have been described. A triple procedure, including intracorneal ring segments, excimer laser and cross linking, has also given some very promising results in progressive keratoconus, providing a significative improvement in visual acuity and topographic data. The combination of excimer laser and intraocular lenses remains a poorly explored lead that might provide some satisfactory results. The objective of this review is to summarize the recent data on excimer laser in keratoconus management.

Femtosecond-Laser Assisted Surgery of the Eye: Overview and Impact of the Low-Energy Concept

This article provides an overview of both established and innovative applications of femtosecond (fs)-laser-assisted surgical techniques in ophthalmology. Fs-laser technology is unique because it allows cutting tissue at very high precision inside the eye. Fs lasers are mainly used for surgery of the human cornea and lens. New areas of application in ophthalmology are on the horizon. The latest improvement is the high pulse frequency, low-energy concept; by enlarging the numerical aperture of the focusing optics, the pulse energy threshold for optical breakdown decreases, and cutting with practically no side effects is enabled.

Outcomes of Gel Stent Implantation for Glaucoma in Patients With Previous Corneal Graft Surgery: A Case Series

PURPOSE

To report a series of 5 cases with successful placement of a minimally invasive glaucoma surgery (MIGS) device for glaucoma refractory to medical management in patients with previous corneal grafts.

METHODS

This is a retrospective analysis of all cases with a Xen45 Gel Stent (Allergan plc, Dublin, Ireland) for ocular hypertension and glaucoma refractory to medical treatment after corneal graft surgery between 2016 and 2019 at the Rothschild Foundation, Paris. We did the imaging studies and studied the intraocular pressure (IOP) and the endothelial cell count preimplantation and postimplantation with a MIGS device.

RESULTS

Five cases were included in this study, demonstrating a well-tolerated, highly effective, and sustained method for controlling the IOP, which was refractory to previous treatment. An average IOP reduction of 70.5% was noted with a needling rate of 20%, and no adverse events were noted except 1 IOP spike day 7 post-op with no long-term effects.

CONCLUSIONS

Glaucoma after graft surgery is a well-known and devastating complication, and as numbers of graft surgery performed increases, so will the incidence of glaucoma. MIGS devices such as the Xen45 Gel Stent (Allergan plc) should become a part of our accepted armory to treat raised IOP refractory to medical treatment without delay.

Corneal Graft Success Rates in HSV Keratitis: A Systematic Review

Herpes Simplex Virus (HSV) has worldwide prevalence. The primary objective of this systematic review was to compare penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) regarding the efficacy and complications of the treatment of corneal scarring caused by herpes simplex keratitis. Out of the 469 articles identified during the combined search of the literature based on the PubMed and Cochrane libraries, 10 retrospective and 2 prospective studies published from January 2010 to December 2019 were included. The study outcomes indicated that both surgical approaches resulted in a comparable improvement of visual acuity (VA). However, DALK demonstrated fewer complications in the majority of studies. Higher graft survival rates were associated with higher acyclovir (ACV) doses (above 800 mg/day), topical steroid and antibiotic drops. In conclusion, in terms of postoperative VA, both PK and DALK demonstrate comparable efficacy. However, DALK, which is applied in less severe HSK cases, is associated with fewer complications and better graft survival rates. High dosages of ACV, topical steroids and antibiotics contribute significantly to improved postoperative outcomes.

Surgeon Preference for Keratoplasty Techniques and Barriers to Performing Deep Anterior Lamellar Keratoplasty

PURPOSE

To identify barriers and facilitators to adopting deep anterior lamellar keratoplasty (DALK) for nonendothelial corneal pathology.

METHODS

An anonymous survey consisting of 22 multiple choice and free text questions was designed to gather information on demographic factors of surgeons and DALK surgical practices. The survey was emailed to members of the kera-net, a global online corneal surgeon/surgery platform.

RESULTS

A total of 100 surgeons completed the survey, most of whom practice in the United States (73%). Most surgeons (89%) reported performing DALK. Surgeons who did not learn DALK during fellowship (34%) tended to be in practice for higher numbers of years (P < 0.001). Surgeons in private practice are more likely to perform DALK versus those in other settings (92.7% vs. 80.8%, P = 0.087). Surgeons performing more corneal surgeries (at least 100 per year) are more likely to perform DALK than those who perform fewer than 100 per year (52% vs. 14%, P = 0.01). Surgeons who perform Descemet membrane endothelial keratoplasty are more likely to perform DALK than those who do not (81.7% vs. 18.3%, P = 0.014). There was also a positive correlation between PK and DALK surgical volumes (Spearman rank correlation coefficient = 0.57, P < 0.001). The main reasons for surgeon preference for DALK over PK were a desire to preserve the endothelium, intraoperative safety, and decreased complications. Longer surgical time and low patient volume were cited as barriers to adoption of DALK.

CONCLUSIONS

Alterations in DALK technique that reduce surgical time and providing more learning opportunities for DALK might improve adoption.

Pneumatic Dissection for Large-Diameter (9-mm) Deep Anterior Lamellar Keratoplasty in Eyes With Previous Anterior Lamellar Keratoplasty

PURPOSE

To evaluate the surgical and 3-year clinical outcomes of modified big-bubble 9-mm deep anterior lamellar keratoplasty (DALK) in eyes with previous ALK (ALK).

METHODS

In this interventional case series, 21 consecutive eyes with unsatisfactory vision after ALK (superficial ALK n = 9; laser-assisted ALK n = 7; and epikeratophakia n = 5) underwent large-diameter (9-mm) DALK. The surgery involved deep trephination based on the anterior segment optical coherence tomography pachymetry measurement at 9-mm diameter, pneumatic dissection from the base of the trephination and limited stromal clearance of the optical zone (6 mm). Main outcome measures were success rates of pneumatic dissection, best spectacle-corrected visual acuity, and complication rates.

RESULTS

Pneumatic dissection with type 1 bubble formation succeeded in 19 (90%) eyes. In the 2 remaining cases, the 6-mm optical zone was cleared by manual dissection. Perforation occurred in one of the latter cases; no procedure was converted to penetrating keratoplasty. One month after complete suture removal, the preoperative mean best spectacle-corrected visual acuity (0.75 ± 0.23 logMAR) improved to 0.09 ± 0.10 logMAR (P < 0.001) and remained stable up to 3 years after surgery. At the final follow-up, refractive astigmatism was ≤4.5 and <6 D in 20 (95%) and 21 (100%) eyes, respectively. Stromal rejection was observed in 2 eyes (10%) and was treated successfully with steroids.

CONCLUSIONS

Even in eyes with previous ALK, pneumatic dissection can be achieved through a modified DALK technique with a low risk of complications and excellent visual and refractive outcomes.

Femtosecond Laser-Assisted Deep Anterior Lamellar Keratoplasty for Keratoconus: Multi-surgeon Results

PURPOSE

To compare the clinical outcomes in femtosecond laser-assisted deep anterior lamellar keratoplasty (F-DALK) to manual non-laser deep anterior lamellar keratoplasty (M-DALK) for keratoconus in a multi-surgeon public healthcare setting.

DESIGN

Single-center, comparative, retrospective interventional case series.

METHODS

Population: Consecutive cases of keratoconus treated with big-bubble F-DALK from August 1, 2015, to September 1, 2018 and big-bubble M-DALK from September 1, 2012, to September 30, 2016.

SETTING

Moorfields Eye Hospital, London.

OBSERVATIONS

Data on preoperative status, operative details, intraoperative and postoperative complications, secondary interventions, and visual outcomes were archived on a customized spreadsheet for analysis. MainOutcomeMeasures: Rate of intraoperative perforation and conversion to penetrating keratoplasty (PK) and the percentage of patients, post removal of sutures (ROS), with corrected distance visual acuity (CDVA) ≥20/40.

RESULTS

We analyzed 58 eyes of 55 patients who underwent F-DALK and 326 eyes of 309 patients who underwent M-DALK. Intraoperative perforation of Descemet membrane occurred in 15 of 58 (25.9%) F-DALK cases compared to 148 of 326 (45.4%) M-DALK cases (P = .006). Intraoperative conversion to PK was carried out in 2 of 58 (3.4%) F-DALK cases compared to 80 of 326 (24.5%) M-DALK cases (P = .001). Post ROS, 86.5% of F-DALK eyes had a CDVA of ≥20/40 (15 ± 7.3 months after surgery) compared to 83.7% of M-DALK eyes (24.9 ± 10.6 months) (P = .825).

CONCLUSION

Laser automation of some steps in DALK for keratoconus may reduce the rate of intraoperative Descemet perforation and the conversion to PK in a multi-surgeon setting.

Stromal peeling for deep anterior lamellar keratoplasty in post-penetrating keratoplasty eyes

Background/aims

To evaluate the clinical outcomes of deep anterior lamellar keratoplasty performed by stromal peeling in eyes that have previously undergone penetrating keratoplasty (PK) for keratoconus.

Methods

Standardised stromal exchange included (1) 9 mm trephination of the recipient bed outside the old PK wound, (2) creation of a partial anterior corneal flap through lamellar dissection across the PK wound, (3) opening the stromal component of the old PK wound using blunt-tipped Vannas scissors until a plane of separation is reached, (4) severing the attachment of the PK surgical scar from the recipient host, (5) peeling the stroma of the PK graft from the underlying tissue and (6) suturing the donor anterior corneal lamella prepared by microkeratome dissection (450 µm depth, 9 mm diameter). Main outcome measures were success rate, best spectacle-corrected visual acuity (BSCVA) and endothelial cell loss (ECL).

Results

Of 21 post-PK eyes, stromal exchange succeeded in all but three cases, which were converted to a two-piece mushroom PK. After complete suture removal, mean BSCVA significantly improved from 0.95±0.39 logMAR preoperatively to 0.23±0.17 logMAR (p<0.001). Mean ECL was 5.4±23.2%. Double anterior chamber formation occurred in eight cases (44%), which all resolved after a single re-bubbling.

Conclusion

In post-PK eyes, stromal exchange can be performed by means of simple peeling without deep anterior lamellar dissection of the previous PK graft. Large-diameter (9 mm) repeat keratoplasty through stromal peeling yields excellent visual outcomes and minimal ECL. Double anterior chamber formation may complicate the postoperative course, but prompt intervention allows successful management.

Comparison of Endothelial Cell Loss following the Big Bubble versus the Microbubble Incision Technique during Deep Anterior Lamellar Keratoplasty in Eyes with Keratoconus

Introduction. Deep anterior lamellar keratoplasty (DALK) is now becoming an increasingly popular surgical technique in treating corneal stromal pathologies with healthy endothelium. Several advantages of DALK over penetrating keratoplasty (PKP) have been described such as maintenance of globe integrity, absence of endothelial rejection, and a low rate of chronic endothelial cell loss (ECL). ECL following PKP results in 50% cell loss after 2 years from the estimated graft endothelial cell density (ECD). Although there are several reports confirming that ECL following DALK is similar to the physiologic cell loss 2 years after surgery, few reports discussed the surgically induced ECL due to difficulty in preoperative imaging of ECD. Materials and Methods. This prospective, interventional study included 20 eyes of 20 patients, who underwent DALK surgery. 11 eyes underwent DALK using the big bubble technique, while 9 eyes underwent the microbubble technique. Postoperative evaluation was done 3 months after surgery and included best spectacle corrected visual acuity (BSCVA), keratometric readings, and refraction measured using an autokeratorefractometer (Topcon KR800, Japan) and endothelial cell density (ECD) using noncontact specular microscopy (Nidek CEM-530, Japan). Results. Regarding postoperative parameters such as postoperative logMAR visual acuity, postoperative mean K, and postoperative K max, there was no statistical difference found between both groups ( $P=0.754$ , $P=0.119$ , and $P=0.970$ , respectively). Regarding change in specular endothelial cell density and percent change in the specular endothelial cell density, again there was no statistical difference between both groups with $P=0.057$ and $P=0.126$ , respectively (significance defined as $P<0.05$ ). Conclusion. ECD is not affected by failure of the big bubble to form and continuing DALK via the microbubble technique.

A new storage medium containing amphotericin B versus Optisol-GS for preservation of human donor corneas

BACKGROUND/AIM

We compared the quality of human donor corneas stored in a cold storage medium containing 2.5 μg/ml of amphotericin B (Kerasave, AL.CHI.MI.A. S.R.L., Ponte San Nicolò, Italy) and Optisol-GS (Bausch & Lomb Inc., Bridgewater, NJ, USA) for 14 days.

METHODS

Sixteen pairs of human donor corneas were collected in Eusol-C (AL.CHI.MI.A. S.R.L., Ponte San Nicolò, Italy). Next, all tissues underwent the first evaluation that included the assessments of central corneal thickness (CCT), endothelial cell density (ECD) measured using both trypan blue staining and specular microscopy, endothelial cell (EC) mortality and morphology, and corneal transparency within 24 hours from recovery (Day 1). Afterwards, one cornea of each pair was transferred into Kerasave or Optisol-GS. ECD and CCT were also assessed at Day 7, and all the metrics were evaluated again at the end of the storage period (Day 14).

RESULTS

At all tested time points, no differences were found in the qualitative (corneal transparency, EC morphology) and quantitative metrics (ECD, CCT, EC mortality) between the Kerasave and the Optisol-GS storage groups. At Day 14, the corneas stored in Kerasave and Optisol-GS showed ECD of 2312±98 and 2335±128 cells/mm² (p=0.886), CCT of 717±17 and 697±19 μm (p=0.454) and central EC mortality of 0.54%±0.40% and 0.14%±0.14% (p=0.719), respectively.

CONCLUSIONS

The new amphotericin B-containing medium Kerasave was comparable to Optisol-GS in terms of preservation of corneal characteristics at 2-8°C for 14 days.

A Foldable Nonpenetrating Keratoprosthesis: Medium to Long-Term Clinical Results in Patients with Corneal Blindness due to Noninflammatory Anterior Cornea Disease

PURPOSE:

To report the medium to long-term safety and performance outcomes of the KeraKlear nonpenetrating artificial cornea (KeraKlear) as the primary procedure in patients with corneal blindness due to noninflammatory anterior cornea disease.

METHODS:

Fifteen patients with corneal blindness (preoperative visual acuity [VA] of ≥20/200) due to a non-inflammatory anterior corneal condition were included in this prospective, single-center study. Preoperative diagnoses included corneal scars, keratoconus, and corneal dystrophies. Diseased corneas were implanted with the KeraKlear (KeraMed Inc., Irvine, California, USA) by a single surgeon (JMV) using a femtosecond laser to create all incisions. Participants were followed up with for as long as 64 months. Uncorrected Snellen VA and postoperative complications were recorded.

RESULTS:

The average age at the time of surgery was 49.6 years old and 67% of patients were female. The patients experienced an average improvement in uncorrected Snellen VA of 7.6 lines (−1.17 logMAR). Average uncorrected vision at the last visit was 20/100 (0.73 logMAR), and median uncorrected vision at the last visit was 20/70 (0.54 logMAR). One patient experienced extrusion of the KeraKlear due to infection. There were no cases of glaucoma, retroprosthetic membrane, or endophthalmitis, the three most common complications of penetrating keratoprostheses (KPro).

CONCLUSIONS:

Medium and long-term outcomes of the KeraKlear indicate that this device is a viable alternative to corneal transplantation as a primary procedure in patients with non-inflammatory causes of corneal blindness, especially when corneal tissue is not available. The KeraKlear does not penetrate into the anterior chamber, and therefore, is less susceptible to the most common complications of penetrating KPro including endophthalmitis, glaucoma, and retroprosthetic membrane. The KeraKlear also has a comparable or improved adverse event rate compared to penetrating keratoplasty.

Construction of bioengineered corneal stromal implants using an allogeneic cornea-derived matrix

The bioengineering of corneal scaffolds that mimic native human cornea has attracted interest owing to the scarcity of donor corneas for the transplantation-based treatment of corneal blindness. However, an optimally engineered corneal tissue for clinical use has yet to emerge. Herein, human corneal tissues discarded during allogeneic corneal transplantation surgery were used to construct allogeneic cornea-derived matrix (ACM) scaffolds with favorable optical properties and structural strength. During scaffold fabrication, collagen and glycosaminoglycan levels were well preserved, while DNA decreased significantly. Scanning electron microscopy revealed the presence of fiber-like structures on the scaffold surface and specific structures featuring multiple interlaced lamellae in cross-sections. Moreover, corneal epithelial cells grown on the ACM formed a continuous multi-stratified epithelium with a strong expression of the corneal epithelial differentiation marker CK3/12, gap junction marker Connexin43, and stem-cell-specific marker p63α, while corneal stromal cells expressed the keratocyte-specific marker KERA and the adhesion marker integrin β1. When the ACM was implanted into rabbit corneal stromal pockets, the rabbit cornea remained transparent throughout the follow-up period. These results indicate that the construction of corneal stromal implants from discarded human corneal tissues may pave the way for the generation of high-quality corneal tissue for transplantation.

[Methods of surgical treatment of keratectasia and analysis of postsurgical quality of vision]

Keratectasias are non-inflammatory dystrophic diseases of the cornea characterized by progressive bilateral thinning of the cornea that lead to deterioration in the quantitative and qualitative characteristics of vision reducing patient's quality of life. The changes can be asymmetrical and destructive. A number of surgeries have been proposed to reduce the negative effects of keratectasia including penetrating keratoplasty and its modifications, implantation of corneal ring segments, corneal cross-linking - alone and in combination with other methods, intrastromal keratoplasty. These methods can improve visual acuity to a certain degree and help slow the progression of keratectasia. This article studies various surgical methods used for treating keratectasia and analyses possible assessment of the quality of vision before and after the treatment.

Corneal transplantation after failed grafts: Options and outcomes

Corneal transplantation is the most commonly performed human tissue transplantation procedure worldwide. Because of the large number of transplants, corneal graft failure has become one of the most common indications for corneal transplantation. The relatively recently developed lamellar transplant techniques have brought about specific potential complications leading to graft failure that may require different approaches to repeat transplantation other than penetrating keratoplasty. On the other hand, these new lamellar techniques also provide novel ways of rescuing failed penetrating grafts, with potential advantages over successive penetrating keratoplasties, such as reduced intraoperative risks and faster visual rehabilitation. We summarize the incidence and risk factors of graft failure for penetrating and lamellar (stromal and endothelial) corneal transplants and discuss the various surgical alternatives currently available to rescue such failed grafts, with a focus on the reported outcomes and limitations.

A porous collagen-based hydrogel and implantation method for corneal stromal regeneration and sustained local drug delivery

Biomaterials designed to replace the diseased cornea could be used to treat corneal blindness where human donor tissue is in short supply, but challenges are the integration of biomaterials with host tissue and cells, avoiding a rapid material degradation and maintaining corneal transparency. Additionally, implantation surgery often triggers an aggressive wound healing response that can lead to corneal thinning and opacity. Here, we report a collagen-based hydrogel with transparency and mechanical properties suitable for replacing a substantial portion of a damaged or diseased corneal stroma. The porous hydrogel permitted migration and population by host cells while maintaining transparency and thickness six months after surgical implantation in an in vivo model of human corneal surgery. With a novel hybrid surgical implantation technique inspired by LASIK refractive surgery, rapid wound healing occurred around implants to maintain biomaterial integrity, transparency and function. Host stromal cell repopulation and regeneration of host epithelium and nerves were observed, as necessary steps towards corneal regeneration. Finally, as a proof-of-principle, the hydrogel loaded with a neuroregenerative drug achieved sustained slow-release drug delivery in vitro. The proposed hydrogel and novel implantation technique together represent a therapeutic approach with translational potential for replacing and regenerating diseased corneal stromal tissue.

Deep Anterior Lamellar Keratoplasty After Previous Anterior Lamellar Keratoplasty to Improve the Visual Outcomes

PURPOSE

To describe a series of patients who underwent deep anterior lamellar keratoplasty (DALK) after previous anterior lamellar keratoplasty (ALK) to improve their visual outcomes.

METHODS

This is a retrospective case series of 9 DALK eyes (9 patients) with a history of previous ALK and an unsatisfactory visual outcome. Surgery was performed in all cases at least 3 years after ALK. Cannula big bubble, air viscobubble, and manual dissection techniques were performed. Preoperative and postoperative best-corrected visual acuity, residual recipient bed thickness, and endothelial cell count were evaluated. Follow-up was at least 24 months for all eyes.

RESULTS

Two subtotal anterior lamellar keratoplasties (through 1 type 1 big bubble and 1 air viscobubble) and 7 manual dissection DALKs were achieved. A small rupture of the residual recipient bed occurred during 1 case, and it was managed without penetrating keratoplasty conversion. Mean best-corrected visual acuity improved from 0.64 to 0.09 logMAR. Postoperative residual recipient central bed thickness was less than 80 μm in all cases. No postoperative complications were recorded at the last follow-up (24-36 months postoperatively).

CONCLUSIONS

Different DALK techniques can be successfully used to improve visual acuity in previous ALK eyes with an unsatisfactory visual outcome.

Effect of Corneal Transplantation on Patient-Reported Outcomes and Potential Predictors: A Systematic Review

PURPOSE

To investigate the effect and potential predictors of corneal transplantation on patient-reported outcomes such as quality of life, visual functioning, and mental health by systematically reviewing the literature.

METHODS

Studies with 1 preoperative and at least 1 postoperative measurement were searched for in relevant literature databases. Methodological quality was assessed using the Quality Assessment Tool for Quantitative Studies, and effect sizes were calculated.

RESULTS

Of 1445 unique publications, 14 studies, including 15 study designs, were described in 16 publications. Four randomized controlled trials, 1 controlled clinical trial, 1 cohort study, and 1 before-after study (BA) were of good quality; 6 BAs were of moderate quality; and 2 BAs were of weak quality. Patients generally improved 12 months after transplantation on health-related quality of life (effect size between 0.08 and -3.06), vision-related quality of life (-0.67 and -6.65), visual functioning (-0.55 and -0.63), and subjective visual symptoms (-0.31 and -0.86). Patient satisfaction was high (-0.95). Patients improved on depression (-0.31) but remained stable on anxiety (-0.05) 4 months after transplantation. Predictors of positive outcomes were lower preoperative visual acuity and visual functioning, better postoperative visual factors, younger age, and male sex.

CONCLUSIONS

Corneal transplantation showed overall beneficial effects on patient-reported outcomes. Knowledge of these effects and predictors might result in better treatment, more patient-centered care, and more realistic expectations on the part of patients and ophthalmologists. Future studies should focus on not only health- and vision-related quality of life but also mental health and labor participation using longitudinal study designs.

Ten-year outcomes of microkeratome-assisted lamellar keratoplasty for keratoconus

BACKGROUND/AIMS

To report the 10-year outcomes of modified microkeratome-assisted lamellar keratoplasty (LK) for keratoconus.

METHODS

In this single-centre interventional case series, 151 consecutive eyes with keratoconus underwent modified microkeratome-assisted LK. Eyes with scars extending beyond the posterior half of the corneal stroma and preoperative thinnest-point pachymetry value of less than 300 μm were excluded. Outcome measures were best spectacle-corrected visual acuity (BSCVA), refractive astigmatism (RA), endothelial cell density, immunological rejection, ectasia recurrence and graft failure rates.

RESULTS

Baseline BSCVA (0.89±0.31 logarithm of the minimum angle of resolution (logMAR)) significantly improved to 0.10±0.12 logMAR at year 3 (p<0.001), and remained stable up to 10 years. At 10 years, 94% of eyes saw ≥20/40, 61% saw ≥20/25 and 24% saw ≥20/20 Snellen BSCVA. At final follow-up, RA exceeding 4.5 dioptres was observed in 5 cases (4%). Endothelial cell loss was 25±17% at 1 year with an annual decline of 2% over 10 years. The 10-year cumulative risk for immunological rejection and graft failure was 8.5%, and 2.4%, respectively. No case developed recurrent ectasia at 10 years.

CONCLUSION

Modified microkeratome-assisted LK results in stable visual and refractive outcomes with low rates of immunological rejection and graft failure in the absence of recurrence of ectasia for at least 10 years.

Pars plana vitrectomy combined with penetrating keratoplasty and transscleral-sutured intraocular lens implantation in complex eyes: a case series

BACKGROUND

The aim of this study was to evaluate the clinical outcomes of pars plana vitrectomy (PPV) combined with penetrating keratoplasty (PKP) and transscleral-sutured intraocular lens (IOL) implantation (IOL-suture) in complex eyes.

METHODS

In this prospective, consecutive interventional case series, patients who underwent PKP combined with PPV and IOL implantation from July 2014 to March 2018 at Yokohama Minami Kyosai Hospital were enrolled. The postoperative best corrected visual acuity (BCVA) (converted to logarithm of the minimal angle of resolution [logMAR] units), intraocular pressure (IOP, mmHg), endothelial cell density (ECD, cells/mm²), graft survival, complications, astigmatism, and spherical equivalent (dioptres [D]) were evaluated.

RESULTS

This study included 11 eyes of 11 patients (three females and eight males; mean age, 61.8 ± 13.9 years) with an injury (n = 6) or bullous keratopathy (n = 5). The BCVA significantly improved from 1.50 ± 0.66 logMAR preoperatively to 0.78 ± 0.59 logMAR (p < 0.001) postoperatively. The baseline ECD significantly decreased from 2396 ± 238 cells/mm² preoperatively to 1132 ± 323 cells/mm² (p < 0.001) postoperatively. Despite two rejection episodes, graft survival rates were 100%. The mean follow-up period was 38.0 ± 20.5 months. Two patients required combined glaucoma surgery, and three patients underwent subsequent glaucoma surgery. Postoperative astigmatism and spherical equivalent were 3.9 ± 3.2 D and 0.29 ± 2.18 D, respectively.

CONCLUSION

The combination of PKP, PPV, and IOL-suture implantation could be a safe and effective approach for eyes requiring anterior segment surgery; however, these eyes are associated with a higher incidence of glaucoma surgery.

Automated digital analysis of intraoperative keratoscopy and its correlation with postoperative astigmatism after big-bubble deep anterior lamellar keratoplasty

PURPOSE

To investigate the correlation between postoperative corneal astigmatism (PCA) and values of intraoperative keratoscopy analyzed with a newly developed automated technique in patients undergoing big-bubble (BB) deep anterior lamellar keratoplasty (DALK).

METHODS

Photographs of keratoscope rings taken at the end of BB-DALK were analyzed using ImageJ for the calculation of "roundness" (R): values = 1 indicate a perfect circle. Pearson's correlation was used to evaluate the relationship between R and PCA that measured 1 week (V1), 3 months (V2), and 18 months (V3), postoperatively. The area under the curve (AUC) of receiver operating characteristic (ROC) curve was used to evaluate the accuracy of R for identifying patients with PCA < 3 diopters (D). The point on the ROC curve nearest to the coordinate (0,100) was used as a cutoff to determine sensitivity and specificity.

RESULTS

Data from 121 patients were included. The mean value of R*was 0.93 ± 0.04 (range 0.76-0.99). R showed a significant correlation with PA at V3 (R = - 0.42, P < 0.01). The ROC curve had an AUC of 0.69 (95% CI 0.59-0.79). A cutoff value of R = 0.93 had a sensitivity of 70.3% and specificity of 61.0% for identifying patients with PA < 3D at V3.

CONCLUSIONS

This new digital analysis of keratoscope rings allows to identify with reasonably good diagnostic accuracy patients with low values of post-DALK astigmatism correctable with spectacles.

Changing trends in corneal transplantation: a national review of current practices in the Republic of Ireland

BACKGROUND

First Irish National Corneal Transplant Registry report.

AIM

To report about current corneal transplantation practices in Ireland including patient demographics, indications and types of transplant performed and to compare the findings with other developed countries.

METHODS

Nationwide retrospective review of the corneal transplants performed in Ireland between 2016 and 2019.

RESULTS

Overall, 536 keratoplasties were carried out: 256 (47.8%) Penetrating Keratoplasties (PK), 212 (39.6%) Descemet Stripping Automated Endothelial Keratoplasties (DSAEK), 30 (5.6%) Descemet Membrane Endothelial Keratoplasties (DMEK), and 25 (4.7%) Deep Anterior Lamellar Keratoplasties (DALK). The most common indication was Keratoconus (KC, 19%), followed by Fuchs endothelial dystrophy (FED, 18.8%), and Pseudophakic bullous keratopathy (PBK, 17%). KC (34%) and re-grafting (17%) were the leading indications for PK, whereas FED and PBK were the major indications for DSAEK (38% and 33%) and DMEK (67% and 20%), respectively. During the period studied, the number of transplants increased from 11.3 to 14 grafts per month. The number of PKs remained stable, whereas Endothelial Keratoplasties, DSAEK and DMEK, increased (3.8 to 5.6 and 0.2 to 1.6 per month, respectively), becoming the most commonly performed grafts since 2018. Only a small number of DALK were performed.

CONCLUSIONS

Corneal transplantation in Ireland is following international trends as endothelial procedures have become the most common approach since 2018. However, a low overall number of transplants is performed in Ireland compared with other countries suggesting that care pathways should be implemented to improve access to corneal transplantation.

Preliminary Results of a Novel Standardized Technique of Femtosecond Laser-Assisted Deep Anterior Lamellar Keratoplasty for Keratoconus

Purpose

To evaluate the feasibility and the initial outcomes of a novel standardized surgical technique of femtosecond laser- (FSL-) assisted big-bubble deep anterior lamellar keratoplasty (BBDALK) for eyes with keratoconus.

Methods

This prospective interventional case series included 11 consecutive FSL-assisted BBDALK procedures performed for the eyes with keratoconus from September 2019 to December 2019. The FSL was used to create (i) an intrastromal channel incision (1.7 mm in length, 4.6 mm in width, 80% depth, and cut energy of 1.70 μJ) and (ii) a 9.0 mm diameter circular lamellar side cut 65 μm above the endothelium (cut energy of 0.90 μJ) intersecting the intrastromal incision. In the operating room, a blunt dissector was used to open the intrastromal channel incision, through which a blunt spatula was inserted, tangentially advanced towards the center of the cornea, and replaced with a blunt cannula for pneumatic dissection. The subsequent surgical steps did not differ from the conventional technique. Main outcome measures were the success rate of pneumatic dissection and the percentage of intraoperative complications.

Results

Eleven eyes of 11 patients (6 males and 5 females; mean age: 34.54 ± 13.23 years) underwent FSL-assisted DALK. Using the FSL, both corneal incisions (lamellar side cut and intrastromal channel incision) were successfully created in all cases without the need for repeat docking or additional dissection. Pneumatic dissection with type 1 bubble formation succeeded in all 11 eyes (100%). DALK surgery was completed uneventfully in all cases. Descemet membrane perforation did not occur in any case, and no procedure was converted to penetrating keratoplasty.

Conclusion

Using standardized FSL parameters for both incision design and cut energy in BBDALK surgery, pneumatic dissection can be achieved in a very high rate of cases with minimal risk of intraoperative complications.

Modified deep anterior lamellar dissection for corneal opacity during vitrectomy: case reports

Background

To introduce a modified deep anterior lamellar dissection technique to improve visibility during surgery for vitreoretinal diseases with coexisting corneal opacity.

Case presentation

Two patients with retinal detachment and coexisting corneal blood staining or corneal decompensation underwent modified deep anterior lamellar dissections followed by vitrectomy. The modified deep anterior lamellar dissection techniques, unlike the dissection and removal of corneal lamellar in a typical deep anterior lamellar keratoplasty, included the creation and preservation of a deep lamellar corneal flap, the retroillumination to visualize and easily remove the remaining opaque stroma on the Descemet membrane, and the big air bubble technique in the eye with endothelial decompensation. The patient’s own cornea flap was sutured back after vitrectomy was done. The modified dissection techniques provided adequate fundus view during vitrectomy while removing as less corneal tissue as possible and decreasing the surgical complications and the requirement of a fresh cornea. Postoperatively, in case 1, the corneal blood staining was gradually absorbed and the vision improved from light perception to counting fingers. In case 2, even though the cornea remained cloudy and the vision was poor, the cornea endothelial decompensation was stable and asymptomatic. Both retinas were attached after silicone oil removal at 6-month follow-up.

Conclusions

This modified and limited deep anterior lamellar corneal dissection procedure appears to be a useful alternative to penetrating keratoplasty, ophthalmic endoscope and temporary keratoprosthesis during the vitrectomy with coexisting corneal opacity.

Total or subtotal full thickness recipient bed cut to repair donor-recipient curvature disparity in cases of DM rupture with manual DALK

PURPOSE

To report how to manage a specific type of Descemet's membrane (DM) rupture during manual DALK with a concurrent donor-recipient disparity of curvature.

METHODS

Case report of two patients that had DM rupture during manual DALK with a concurrent donor-recipient disparity of curvature; the recipient bed was flatter (post-infectious scar, case 1) and steeper (keratoglobus, case 2) than the donor. Preoperative diagnosis, clinical exam, and best spectacle correct visual acuity (BSCVA) have been reported. A subtotal full-thickness circular cut of the recipient bed was performed to resolve a persistent double AC in case 1 (recipient flatter than donor). A total full-thickness circular cut of the recipient bed, creating a graft made by a DALK allograft and a "DSEK autograft," was performed to avoid a refractory double AC in case 2 (recipient steeper than donor). Evaluated outcomes included postoperative BSCVA, endothelial cell count (ECC), graft clarity, rejection, and presence/absence of double AC.

RESULTS

Surgery was successful in resolving/avoiding double AC. VA improved in both cases. No episodes of rejection were recorded. Graft remained clear at the last follow-up (6 years for case 1 and 4 years for case 2).

CONCLUSION

The existence of a donor-recipient curvature disparity should be investigated as a possible underlying mechanism of refractory double AC. Total or subtotal full thickness recipient bed cut may be considered to repair donor-recipient curvature disparity in cases of DM rupture occurring during manual DALK. Repairing the DM rupture and avoiding a conversion to PK in high-risk transplant cases are crucial.

Manual deep anterior lamellar keratoplasty after partial unintentional full-thickness trephination

PURPOSE

The aim of this study was to describe a surgical technique to perform deep anterior lamellar keratoplasty (DALK) despite inadvertent full thickness trephination in one quadrant.

METHODS

Case report of a 19-year-old boy who underwent DALK for visually significant post-infectious stromal scar in his left eye. An unintentional full thickness trephination occurred in the upper-nasal quadrant at the beginning of the surgery. After suturing the perforated area, manual DALK was performed, and an air bubble was left in the anterior chamber. Evaluated outcomes included best spectacle corrected visual acuity (BSCVA), residual recipient bed thickness, endothelial cell count (ECC), graft clarity, rejection, and presence/absence of double anterior chamber.

RESULTS

The surgery was completed without any further complications. No double anterior chamber or Urrets-Zavalia syndrome was observed on the first postoperative day. Mean residual recipient bed thickness was 72 μm and regular. ECC was 2446 cell/mm². BSCVA at 18 months of follow-up was 0.9. There were no episodes of rejection, and the graft remained clear at the last follow-up (4 years).

CONCLUSION

Inadvertent partial full thickness trephination of the recipient cornea is a largely preventable but possible complication during DALK. Penetrating keratoplasty conversion can be avoided by performing a manual dissection DALK.

Corneoscleral contact lenses for visual rehabilitation after keratoplasty surgery

PURPOSE

To report the use of corneoscleral lenses (CSL) in keratoconus patients who were unsatisfied with their visual outcomes after keratoplasty surgery.

METHODS

Eleven consecutive cases with unsatisfactory vision with spectacles, due to irregular astigmatism, preferred to try CSL before SL due to handling or economic issues. An eye examination included refraction and visual acuity assessment, anterior eye biomicroscopy, ocular fundus examination, corneal topographic analysis, endothelial-cell count (ECC) and evaluation of corneal biomechanical parameters (corneal resistance factor, CRF; corneal hysteresis, CH; corneal-compensated intraocular pressure, IOPcc). The fitting process was performed using a diagnostic fitting set. Subjective visual quality and comfort, and CSL usage time were also recorded. Patients were monitored for 1 year.

RESULTS

Two patients presented intolerance to CSL. Therefore, nine patients (6 males and 3 females; the mean±SD age, 44.56 ± 17.33 years, range 27-82) were fitted with CSL. The log MAR visual acuity of these eyes improved significantly with CSL in relation to the best spectacle-corrected vision (0.02 ± 0.06 vs 0.22 ± 0.15, respectively; p = 0.007). Patients reported prolonged usage times (an average of 9.78 ± 1.99 h; range, 8-14). No significant adverse ocular effects or clinically relevant changes in ocular parameters (ECC, CH, IOPcc, central corneal thickness and keratometry; all p > 0.05), visual quality, comfort rating or usage time were found during the 1-year follow-up.

CONCLUSION

Corneoscleral lenses could be fitted in non-severe cases after keratoplasty surgery with optimal visual results as they can be a safe and healthy alternative option.

Deep anterior lamellar keratoplasty outcomes in macular and granular corneal dystrophy - A comparative cross-sectional study

Purpose

To compare the functional and anatomical outcomes (in terms of graft uptake and rejection/failure) of deep anterior lamellar keratoplasty (DALK) in stromal corneal dystrophy (macular and granular).

Methods

Sixteen eyes with macular corneal dystrophy (MCD; group A) and 10 eyes with granular corneal dystrophy (GCD; group B) underwent successful DALK by big bubble technique or layer-by-layer dissection.

Results

Both groups showed significant improvement in their best-corrected visual acuity postoperatively (postoperative P value in MCD and GCD was 0.00001 and 0.0008, respectively) with no statistically significant differences between the two groups (P = 0.77) at 1 year. Postoperative endothelial count did not drop significantly in group A (MCD, P= 0.1553). Only in seven eyes preoperative endothelial count could be obtained (due to dense stromal corneal opacity), but there was a significant endothelial count difference between preoperative and postoperative count in group B (GCD, P= 0.0405) at the end of 1 year postoperatively which could be because of age and stage of disease (advanced granular dystrophy) and also because of small sample size of GCD compared with MCD. Intergroup comparison between the two groups showed no statistically significant difference (P = 0.6353) with good postoperative outcome in both groups.

Conclusion

DALK can be successfully done in both groups and results are comparable. However, long-term outcomes on a large scale need to be further evaluated.

Burr-Assisted Anterior Lamellar Keratoplasty (DALK) in Patients with Corneal Stromal Scarring: A Case Series

Purpose

To describe a modified technique of deep anterior lamellar keratoplasty (DALK) assisted by diamond ophthalmic burr (DOB) in two patients with corneal stromal scarring.

Methods

Two patients with corneal stromal scarring underwent a modified DALK technique with corneal stromal polishing assisted by a DOB until the level of the Descemet membrane.

Results

There were no intra- or postoperative complications. Six months postoperatively, the corneal graft was clear, while corrected distance visual acuity improved in both cases.

Conclusions

Burr-assisted DALK seems to represent an alternative surgical technique in patients with corneal stromal scarring.

Electronic supplementary material

The online version of this article (10.1007/s40123-020-00248-8) contains supplementary material, which is available to authorized users.

Predictors of Bubble Formation and Type Obtained With Pneumatic Dissection During Deep Anterior Lamellar Keratoplasty in Keratoconus

PURPOSE

To identify predictors of bubble formation and type during big-bubble deep anterior lamellar keratoplasty (BB-DALK) performed in keratoconus at different stages of severity.

DESIGN

Retrospective Cohort Study.

METHODS

Setting: University Magna Græcia (Catanzaro, Italy); Study Population: Consecutive keratoconus patients undergoing BB-DALK from September 2014 to February 2019.

OBSERVATION PROCEDURE

Keratometric astigmatism, mean keratometry value (K-mean), highest keratometry value (K-max), thinnest point, anterior segment optical coherence tomography (AS-OCT)-based stage of ectasia.

MAIN OUTCOME MEASURES

Rate of bubble formation and type; number and fate of micro-/macroperforation; conversion to mushroom keratoplasty (MK); comparison of parameters in patients with bubble formation vs failure and in type 1 vs type 2 bubble; areas under the curves (AUC) of preoperative parameters for distinguishing between bubble types.

RESULTS

Pneumatic dissection succeeded in 113 of 155 eyes (72.9%), with 100 type 1 bubbles (88.4%), 11 type 2 (9.8%), and 2 mixed-type (1.8%). Microperforations were managed conservatively in type 1 bubbles; macroperforations occurring in both types of bubbles required conversion to MK. Preoperative K-mean and K-max values were significantly higher in eyes in which bubble formation succeeded (respectively, P = .006 and P < .013). Type 1 bubbles formed in eyes with significantly lower age, K-mean, and AS-OCT stages and higher pachymetric values (always P < .029). Age had the highest diagnostic power for discrimination between bubble types, followed by AS-OCT stage, pachymetry, K-mean, and astigmatism (respectively, AUC = 0.861, 0.779, 0.748, 0.700, 0.670).

CONCLUSIONS

Older age and advanced stages of keratoconus were predictors of type 2 bubble formation during BB-DALK that was associated with an increased risk of complications.

A retrospective study comparing DALK and PKP in the treatment of necrotizing stromal keratitis

PURPOSE

To compare the clinical outcomes of deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP) in the treatment of necrotizing stromal keratitis (NSK).

METHODS

A retrospective study of NSK patients who underwent keratoplasty between January 2015 and December 2017 in the Third Xiangya Hospital was carried out. Data including preoperative and postoperative best corrected visual acuity (BCVA), intraocular pressure, graft survival rates, corneal endothelial cell density, corneal topography and thickness were reviewed and analyzed by SPSS 23.0 software.

RESULTS

Fifty patients were involved. Twenty-five patients received DALK, and the other half received PKP. The average follow-up period was 10.28 ± 5.92 months. At the end of the follow-up period, there were no significant differences in postoperative BCVA, recurrence of virus, graft rejection or graft failure between the two groups. There were also no significant differences in average central corneal thickness postoperatively at 3 months. However, the average corneal endothelial cell density at 3 months was significantly higher in the DALK group (2121.12 ± 450.80 cell/mm² in the DALK group versus 1812.16 ± 340.38 cell/mm² in the PKP group, P = 0.009).

CONCLUSION

Both DALK and PKP could increase visual acuity and prevent the progression of NSK. There were no significant differences between DALK and PKP in postoperative BCVA, rate of rejection, graft failure or recurrence rate. DALK significantly reduced the loss of corneal endothelial cells.

Outcomes of big-bubble deep anterior lamellar keratoplasty for pediatric keratoconus

PURPOSE

To evaluate the outcomes and complications of deep anterior lamellar keratoplasty (DALK) performed for pediatric keratoconus.

METHODS

This retrospective study enrolled 44 consecutive eyes of 39 keratoconus-affected children (≤ 18 years of age). All patients underwent big-bubble DALK from March 2004 to June 2016. The outcome measures included postoperative best spectacle-corrected visual acuity (BSCVA), manifest refraction, keratometry readings, and complications.

RESULTS

The mean participant age was 16.8 ± 1.4 years, and the mean follow-up period was 68.5 ± 39.9 months. Successful big bubble was achieved in 33 eyes (75.0%), while the surgical technique was predescemetic DALK in 11 (25.0%). The mean BSCVA changed from 1.34 ± 0.49 LogMAR preoperatively to 0.24 ± 0.10 LogMAR postoperatively (P < 0.001). The mean keratometry decreased from 59.54 ± 5.17 D preoperatively to 46.23 ± 2.17 D postoperatively (P < 0.001). The complications encountered during the study period were intraoperative Descemet's membrane perforation (n = 5, 11.4%), the Urrets Zavalia syndrome (n = 1, 2.3%), graft epithelial problems (n = 3, 6.8%), subepithelial graft rejection (n = 5, 11.4%), high intraocular pressure (n = 8, 18.2%), and traumatic wound dehiscence (n = 2, 4.6%). Suture-related complications included premature loosening (n = 13, 29.6%), broken sutures (n = 12, 27.3%), suture-tract vascularization (n = 6, 13.6%), suture-associated abscesses (n = 5, 11.4%), and suture cheese wiring (n = 2, 4.6%). A clear graft was found in 40 eyes (90.9%) at the last follow-up examination.

CONCLUSION

This study showed promising results with big-bubble DALK in keratoconus-affected children. A frequent and close follow-up with dedicated parental involvement is essential for the early recognition and management of postoperative complications.