Component corneal surgery: An update

Crescentic Autograft-Graft Salvage Technique for Undersized Donor Lenticules in Superficial Anterior Lamellar Keratoplasty

PURPOSE

To describe the use of crescentic autograft as a graft salvage technique for inadvertently undersized donor lenticules in superficial anterior lamellar keratoplasty (SALK).

METHODS

A prospective interventional study included 5 eyes of 4 patients who underwent SALK and had an inadvertently undersized donor lenticule. The described technique involves the preparation of a crescent-shaped graft from the host lenticule itself that is matched to fit into the remaining bare recipient stromal bed.

RESULTS

At 6-week follow-up, the crescentic autograft was uniformly epithelized along with the donor tissue. There were no incidences of graft dehiscence, rejection, or infection.

CONCLUSIONS

Crescentic autograft from the host lenticule offers a simple, easy-to perform, and unique technique to manage cases of undersized donor lenticules in SALK with no additional risks.

Human cornea-derived extracellular matrix hydrogel for prevention of post-traumatic corneal scarring: A translational approach

Corneal scarring and opacification are a significant cause of blindness affecting millions worldwide. The current standard of care for corneal blindness is corneal transplantation, which suffers from several drawbacks. One alternative approach that has shown promise is the use of xenogeneic corneal extracellular matrix (ECM), but its clinical applicability is challenging due to safety concerns. This study reports the innovative use of human cornea-derived ECM to prevent post-traumatic corneal scarring. About 30 - 40% of corneas donated to the eye banks do not meet the standards defined for clinical use and are generally discarded, although they are completely screened for their safety. In this study, human cornea-derived decellularized ECM hydrogel was prepared from the non-transplantation grade human cadaveric corneas obtained from an accredited eye-bank. The prepared hydrogel was screened for its efficacy against corneal opacification following an injury in an animal model. Our in vivo study revealed that, the control collagen-treated group developed corneal opacification, while the prophylactic application of human cornea-derived hydrogel effectively prevented corneal scarring and opacification. The human hydrogel-treated corneas were indistinguishable from healthy corneas and comparable to those treated with the xenogeneic bovine corneal hydrogel. We also demonstrated that the application of the hydrogel retained the biological milieu including cell behavior, protein components, optical properties, curvature, and nerve regeneration by remodeling the corneal wound after injury. The hydrogel application is also sutureless, resulting in faster corneal healing. We envision that this human cornea-derived ECM-based hydrogel has potential clinical application in preventing scarring from corneal wounding. STATEMENT OF SIGNIFICANCE: There are significant challenges surrounding corneal regeneration after injury due to extensive scarring. Although there is substantial research on corneal regeneration, much of it uses synthetic materials with chemical cross-linking methods or xenogeneic tissue-based material devices which have to undergo exhaustive safety analysis before clinical trials. Herein, we demonstrate the potential application of a human corneal extracellular matrix hydrogel without any additional materials for scarless corneal tissue regeneration, and a method to reduce the wasting of donated allogenic corneal tissue from eye banks. We found no difference in efficacy between the usage of human tissues compared to xenogeneic sources. This may help ease clinical translation and can be used topically without sutures as an outpatient procedure.

Tuck In Femtosecond Laser Assisted Anterior Lamellar Keratoplasty (T-FALK) for the Management of Superficial Anterior Corneal Scars-A Modified Technique

PURPOSE

To report a modified sutureless and glue-less technique, termed tuck in femtosecond laser assisted anterior lamellar keratoplasty (T-FALK), and to achieve a good graft-host junction apposition.

METHODS

This is a prospective interventional case series of 15 eyes of 15 patients who underwent T-FALK. Depth of the anterior corneal scar was assessed using anterior segment optical coherence tomography (ASOCT). The donor and recipient lenticules were prepared using femtosecond laser. After removing the recipient anterior scarred lenticule, the transparent donor lenticule was positioned on the recipient bed and margins tucked in under the recipient cornea. A bandage contact lens was applied for 3 weeks. Postoperatively, topical antibiotic and steroid combination eye drops were given, and the assessment of healing of the graft-host junction was done using ASOCT.

RESULTS

A total of 15 patients (8 men and 7 women) underwent T-FALK. Six patients had superficial corneal opacities after healed microbial keratitis, 5 patients had spheroidal corneal degeneration, 3 patients had Salzman nodular degeneration, and 1 patient had vortex keratopathy. No intraoperative or postoperative complications were noted during T-FALK. All patients had good graft-host junction apposition postoperatively, as demonstrated by ASOCT.

CONCLUSIONS

Sutureless and glue-less T-FALK can be the best way ahead for management of superficial anterior corneal scars with good visual outcome.

Demographic and clinical profile, surgical outcome, and quality of life in patients who underwent bilateral lamellar corneal grafts

Purpose:

Lamellar corneal grafts have revolutionized the management of corneal blindness by replacing only the disease specific corneal layers. To the best of our knowledge, there is no study in literature describing the outcomes of bilateral lamellar keratoplasty in the Indian population. The aim of this work was to study the demographic profile, surgical outcomes, and quality of life in patients who underwent bilateral lamellar keratoplasty and to assess the correlation between these three.

Methods:

An observational cross-sectional study was conducted on 47 patients who underwent bilateral deep anterior lamellar keratoplasty (DALK) (n = 31) or descemet stripping automated endothelial keratoplasty (DSAEK) (n = 16) with a minimum follow-up of 6 months after the second surgery. Demographic parameters were collected by interview, surgical outcomes by clinical examination, and quality of life by a questionnaire.

Results:

A total of 47 patients were evaluated, women 42.56%, (n = 20) and men 57.44% (n = 27) with 38.3% being in 18–30 years age group and 23.4% above 60 years; 17.02% patients had a good socioeconomic status (score >60) and 61.70% had poorer socioeconomic status (score <50). Quality of life score (VR-QoL) was ≥50 in 82.9% patients and ≥70 in 14.89%. No significant association existed between VR-QoL scores and demographic factors. However, statistically significant association existed between VR-QoL and age of patient (P < 0.05), postoperative vision (P ≤ 0.05), and contrast sensitivity (P ≤ 0.01).

Conclusion:

Bilateral lamellar corneal grafts provide satisfactory visual outcomes compatible with day-to-day functioning. VR-QoL has a direct correlation to the age, visual acuity, contrast sensitivity, and inverse correlation with lenticule thickness in DSAEK and residual bed thickness in DALK.

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).

Current development of alternative treatments for endothelial decompensation: Cell-based therapy

Current treatment for corneal endothelial dysfunction consists in the replacement of corneal endothelium by keratoplasty. Owing to the scarcity of donor corneas and the increasing number of transplants, alternative treatments such as cell-based therapies are necessary. In this article, we highlight the biological aspects of the cornea and the corneal endothelium, as well as the context that surrounds the need for new alternatives to conventional keratoplasty. We then review some of those experimental treatments in more detail, focusing on the development of the in vitro and preclinical phases of two cell-based therapies: tissue-engineered endothelial keratoplasty (TE-EK) and cell injection. In the case of TE-EK graft construction, we analyse the current progress, considering all the requirements it must meet in order to be functional. Moreover, we discuss the inherent drawbacks of endothelial keratoplasties, which TE-EK grafts should overcome in order to make surgical intervention easier and to improve the outcomes of current endothelial keratoplasties. Finally, we analyse the development of preclinical trials and their limitations in terms of performing an optimal functional evaluation of cell-based therapy, and we conclude by discussing early clinical trials in humans.

Four in one: Four recepients with a single donor tissue - A novel concept for eye transplantation surgery post-COVID-19

A donor corneo-scleral button was dissected into four parts using a simple manual technique. The anterior corneal lamellae was stripped from the Descemet's Membrane (DM) and Deep Anterior Lamellar Keratoplasty (DALK) was performed in a patient with advanced keratoconus after removing the recipient's stroma using the big bubble technique. Descemet's Membrane Endothelial Keratoplasty (DMEK) was done with the stripped donor DM in a patient with Fuch's endothelial dystroph (FECD). The cadaveric limbal stem cells from the tissue were used for simple limbal epithelial transplantation (SLET) in a Steven- Johnson Syndrome (SJS) with localized limbal stem deficiency and symblepharon. The sclera was used to revise a leaking hypotonus bleb in an advanced single-eyed glaucoma patient. No intraoperative or postoperative complications were observed. At 1 year, all the 4 cases retained healthy transplanted tissues with good visual outcomes. Shortage of donor eyes is a global problem and with the present COVID-19 scenario the situation is bound to worsen. The advent of customized component corneal transplantation using simple cost-effective techniques will be the future trend in the years to come.