Severe ocular surface disease can result in limbal stem cell deficiency (LSCD), a condition leading to decreased visual acuity, photophobia, and ocular pain. To restore the ocular surface in advanced stem cell deficient corneas, an autologous or allogenic limbal stem cell transplantation is performed. In recent years, the risk of secondary LSCD due to removal of large limbal grafts has been significantly reduced by the optimization of cultivated limbal epithelial transplantation (CLET). Despite the great successes of CLET, there still is room for improvement as overall success rate is 70% and visual acuity often remains suboptimal after successful transplantation. Simple limbal epithelial transplantation reports higher success rates but has not been performed in as many patients yet. This review focuses on limbal epithelial stem cells and the pathophysiology of LSCD. State-of-the-art therapeutic management of LSCD is described, and new and evolving techniques in ocular surface regeneration are being discussed, in particular, advantages and disadvantages of alternative cell scaffolds and cell sources for cell based ocular surface reconstruction.

/pdf/limbal-stem-cell-deficiency-current-treatment-options-and-2st51oytyc.pdf

Limbal Stem Cell Deficiency: Current Treatment Options and Emerging Therapies

Bacterial contamination of tissue allografts obtained from cadaveric donors has been a serious cause of morbidity and mortality in recipients. Recent cases of fatal and nonfatal bacterial infections in recipients of contaminated articular cartilage (distal femur) and tendon allografts have called attention to the importance of avoiding tissue donors suspected of carrying infectious disease, of not processing donated tissue carrying virulent bacteria, the occurrence of falsely negative final sterility tests, and the need to sterilize tissues. These cases demonstrated that contamination can arise from an infected donor, during tissue removal from cadaveric donors, from the processing environment, and from contaminated supplies and reagents used during processing. Final sterility testing can be unreliable, especially when antibiotics remain on tissues. There is an increasing need for control of microbial contamination in tissue banks, and sterilization of tissue allografts should be recommended whenever possible.

Bacterial infection transmitted by human tissue allograft transplantation.

Simple limbal epithelial transplantation (SLET) is an innovative limbal stem cell transplantation technique that has gained increasing popularity over the last few years. Different groups from across the world have published the clinical results of SLET in large case series with varying types and severities of limbal stem cell deficiency (LSCD). This review attempts to place all the available knowledge on SLET together in one place for the benefit of not only cornea specialists and trainees but also for residents and general ophthalmologists. It follows a balanced approach of blending evidence with experience by providing an objective analysis of published results along with helpful insights from subject experts, starting from preoperative considerations including the role of newer imaging modalities to the technical aspects of the surgery itself and the management of possible complications. Original data and novel insights on allogeneic SLET for bilateral LSCD are included in the review to address the few remaining lacunae in the existing literature on this topic. This review intends to inform, educate, and empower all aspiring and practicing SLET surgeons to optimize their clinical outcomes and to have maximal positive impact on the lives of the individuals affected by unilateral or bilateral chronic LSCD.

Simple limbal epithelial transplantation (SLET): Review of indications, surgical technique, mechanism, outcomes, limitations, and impact.

Purpose To conduct a systematic review on outcomes of three different techniques of autologous limbal stem cell transplantation (LSCT): conjunctival-limbal autografting (CLAu), cultivated limbal epithelial transplantation (CLET) and simple limbal epithelial transplantation (SLET), in unilateral limbal stem cell deficiency (LSCD). Methods Literature searches were conducted in MEDLINE (Ovid), Embase, Web of Science and Cochrane Central Register. Standard systematic review methodology was followed using Meta-analysis of Observational Studies in Epidemiology guidelines. Studies with a sample size of more than 10 eyes were included. The primary outcome measure of efficacy was restoration of a completely epithelised, stable and avascular corneal surface (anatomical success). The secondary outcome measure of efficacy was improvement in best-corrected visual acuity of two-lines or greater (functional success). Results The review identified 22 non-comparative case series, which included 1023 eyes. Ocular burns were the major (88%) indication for surgery. Overall, at a median postoperative follow-up of 1.75 years, autologous LSCT for unilateral LSCD showed anatomical and functional success rates of 69% and 60%, respectively, without any serious adverse events in the donor eye. The follow-up duration and indications for surgery were comparable across all groups (p>0.05). The anatomical and functional success rates of SLET (78%; 68.6%) and CLAu (81%; 74.4%) were comparable, and significantly better than those of CLET (61.4%; 53%; p=0.0048). Conclusion Autologous LSCT is a safe and effective treatment for unilateral LSCD. In the absence of randomised controlled trials, existing evidence clearly suggests that clinical outcomes are better with SLET and CLAu as compared with CLET.

https://bjo.bmj.com/content/bjophthalmol/104/2/247.full.pdf

Autologous limbal stem cell transplantation: a systematic review of clinical outcomes with different surgical techniques.

The corneal epithelium consists of stratified epithelial cells, sparsely interspersed with dendritic cells (DCs) and a dense layer of sensory axons. We sought to assess the structural and functional correlation of DCs and sensory nerves. Two morphologically different DCs, dendriform and round-shaped, were detected in the corneal epithelium. The dendriform DCs were located at the sub-basal space where the nerve plexus resides, with DC dendrites crossing several nerve endings. The round-shaped DCs were closely associated with nerve fiber branching points, penetrating the basement membrane and reaching into the stroma. Phenotypically, the round-shaped DCs were CD86 positive. Trigeminal denervation resulted in epithelial defects with or without total tarsorrhaphy, decreased tear secretion, and the loss of dendriform DCs at the ocular surface. Local DC depletion resulted in a significant decrease in corneal sensitivity, an increase in epithelial defects, and a reduced density of nerve endings at the center of the cornea. Post-wound nerve regeneration was also delayed in the DC-depleted corneas. Taken together, our data show that DCs and sensory nerves are located in close proximity. DCs may play a role in epithelium innervation by accompanying the sensory nerve fibers in crossing the basement membrane and branching into nerve endings.

/pdf/intraepithelial-dendritic-cells-and-sensory-nerves-are-1ji3wdngri.pdf

Intraepithelial dendritic cells and sensory nerves are structurally associated and functional interdependent in the cornea.

Purpose To standardize the technique of ex vivo culture of limbal epithelial stem cells (LESCs) using locally available adapted methods and evaluate the outcome of transplantation in patients with limbal stem cell deficiency. Methods Limbal tissue specimens were isolated from cadaveric corneoscleral rims, living related donors, or contralateral eye of the patients. Harvested tissue was cultured on denuded human amniotic membrane (dHAM) using various techniques to stabilize dHAM. The optimization of in vitro culture conditions was achieved by modifications in culture media (culture media 1 and 2). The LESCs were cultured in both types of media for 2 weeks, and growth patterns were observed. Expanded cells were further characterized by immunocytochemistry (K3/12, K19, and ABCG2) and reverse transcriptase polymerase chain reaction (K12, Cx43, Pax6, ABCG2, p63, and K19). The cultivated epithelium was transplanted in 50 patients with total and partial limbal stem cell deficiencies. Results Stabilization of dHAM was successfully achieved using coverslips. The outgrowth was observed within 1-3 days of culture using both types of culture media (P = 0.20), but cultures in culture medium 1 reached confluency faster than cultures in culture medium 2 (P = 0.0004). Histopathological analysis showed multilayer formation and immunostaining, and reverse transcriptase polymerase chain reaction data confirmed the expression of both stem cell markers (K19, p63, and ABCG2) and differentiation markers (K3, K12, and Cx43). Patients who had undergone limbal stem cell transplantation showed a stable ocular surface with improved visual acuity over a long-term follow-up period. Conclusions LESCs were successfully cultured using locally available adapted methods, and their clinical benefits verified by transplantation.

Culture of corneal limbal epithelial stem cells: experience from benchtop to bedside in a tertiary care hospital in India

We describe a technique of in-the-bag phacoemulsification of large, hard, leathery brown nuclear cataracts. A large crater approximately 6.0 mm diameter is created by down-slope sculpting up to 90% of nuclear thickness, leaving the outer nuclear rim intact. The edge of the crater is held with the phaco probe using high vacuum, and small wedge-shaped pieces are created with a chopper. These small pieces are emulsified in the space created by the crater. This technique permits in-the-bag phacoemulsification of large brown cataracts without complications.

Crater-and-chop technique for phacoemulsification of hard cataracts

Aims: To evaluate outcomes of deep anterior lamellar keratoplasty (DALK) in pediatric eyes with unilateral severe chemical injury which have undergone autologous simple limbal epithelial transplant (SLET). Settings and Design: The study design was a retrospective case series. Materials and Methods: This retrospective, case series of all children <16 years of age that have undergone DALK following autologous SLET procedure in unilateral severe chemical injury evaluates the outcomes and complications in the setting of a tertiary care center in North India. Statistical Analysis Used: Nonparametric data have been expressed as median (range), parametric qualitative data as percentage, and quantitative data as a mean ± standard deviation. Spearman's correlation coefficient is used for finding a correlation between variables. Results: Eleven eyes of 11 children (5 male and 6 female) with a mean age of 8.9 ± 4.7 years underwent DALK following ocular surface reconstruction with autologous SLET earlier for unilateral severe chemical injury with limbal stem cell deficiency. Follow-up ranged from 6 to 18 months (13.00 ± 4.58 months) following DALK procedure. All patients with a minimal follow-up of 6 months were evaluated for visual outcomes. Visual acuity ranged from 0.3 to 3 logMAR units (0.6 ± 0.2 logMAR units). Complications were encountered in three patients. Anatomical success was seen in 72.72% patients and visual success was noted in 54.54% patients. Conclusions: DALK is a feasible option in children with severe unilateral chemical injury who have undergone ocular surface reconstruction with autologous SLET procedures.

Outcomes of deep anterior lamellar keratoplasty following autologous simple limbal epithelial transplant in pediatric unilateral severe chemical injury.

Laboratory confirmation of chlamydial antigen in clinically suspected cases of chlamydial eye infections is important, as similar clinical picture can be presented by different infective or noninfective causes. We retrospectively analyzed the presence of Chlamydia trachomatis antigen in 690 clinically suspected patients over the last 8 years (2009–2016). The chlamydial antigen was detected using direct immunofluorescence assay. Overall, Chlamydia-specific antigen positivity was 45.5%. The highest positivity was seen in 2014 (68.6%) and the least in 2016 (9.4%). The antigen positivity in years 2015 (13.4%) and 2016 (9.4%) was significantly less than in all the previous study years (P

Chlamydia trachomatis Antigen Positivity in Patients with Different Ocular Manifestations over 8 Years.

Removal of "acrylic pearls" from acrylic lenses.

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