Corneal pathologies are a major cause of blindness and visual impairment, especially in the developing world. However, not only is there a global shortage of donor corneal tissue, but a significant proportion of these blinding pathologies also carry an unfavourable long-term prognosis for conventional corneal transplantation. In the last few decades, there has been a spurt of research on developing alternate approaches to address corneal blindness, including stem cell therapy. After the discovery of epithelial stem cells at the limbus, successful cell-based approaches to treat severe ocular surface disease were developed and have subsequently become widely practised across the world. More recently, mesenchymal stem cells were identified near the epithelial stem cells at the limbus, providing a unique opportunity to develop regenerative therapies for both corneal epithelial and stromal pathologies. This review firstly emphasises on qualifying limbal stem cells as either epithelial or mesenchymal and then summarises all the existing knowledge on both cell types and their individual roles in corneal regeneration. The review describes the history, indications, techniques, and outcomes of the different methods of limbal epithelial stem cell transplantation and elaborates on the potential applications of limbal mesenchymal stem cell therapy. ARTICLE HISTORY

This study aimed to identify the anterior segment high-resolution optical coherence tomography (HR-OCT) and HR-OCT angiography (HR-OCTA) features suggestive of limbal stem cell deficiency (LSCD) as confirmed by both impression cytology (IC) and in vivo confocal microscopy (IVCM). This was a single-centre prospective cross-sectional study including 24 eyes of 22 patients with clinical suspicion of LSCD based on peripheral superficial corneal vascularisation and scarring. On IC and IVCM, performed and interpreted by blinded observers, 12 eyes each were diagnosed with and without LSCD. Additionally, 10 eyes of 5 healthy volunteers with no ocular pathology were also imaged. The 136 HR-OCT/A images of these 34 eyes were analysed with respect to 12 imaging parameters; the parameters most suggestive of LSCD were identified and the sensitivity and specificity were calculated. In the LSCD group, the most common aetiology was ocular chemical burns (83%), whereas in the non-LSCD group, the most common aetiology was viral keratitis (67%). Multiple logistic regression analysis revealed that mean epithelial reflectivity, mean stromal reflectivity, and mean superficial vascular density were the parameters that were diagnostic of LSCD on HR-OCT/A (p < 0.0001). A ratio of the mean epithelial reflectivity to stromal reflectivity of >1.29 corresponded with a high sensitivity (91.7%) and specificity (98.75%); while a mean superficial vascular density score of >0.38 corresponded with a sensitivity of 97.9% and specificity of 73.8%. In conclusion, HR-OCT/A as a non-invasive imaging modality could prove to be a useful tool for confirming the diagnosis of LSCD, with potential clinical and research applications.

To describe the histopathological characteristics of limbal stem cell deficiency (LSCD) due to chronic vernal keratoconjunctivitis (VKC).Methods: This retrospective study included 14 eyes of 13 patients who underwent simple limbal epithelial transplantation for total LSCD from 2017 to 2018. The histological characteristics of the excised fibrovascular pannus were compared between 2 groups of 7 eyes, each with LSCD due to VKC and chemical burns (CB). Histological characteristics and type of inflammation were studied using special stains and immunohistochemistry. Fisher exact test was used to detect the statistical significance of the histological differences between both groups.Results: Epithelial hypertrophy, epithelial downgrowth, and eosinophilic infiltration were noted in all eyes in the VKC group (7/7, 100%). Epithelial hypertrophy was noted in 3 of the 7 (42.8%) eyes in the CB group, whereas epithelial downgrowth and eosinophilic infiltrates were absent. The average chronic inflammatory score of the pannus (5.28) was higher in VKC than in CB (3.85; P = 0.1080). The presence of goblet cells was higher in the CB group (5/7, 1.4%) than in the VKC group (3/4, 2.8%), although not statistically significant. Other histological differences between the groups were not statistically significant. Conclusions:The histopathological features of LSCD in VKC reveal some distinctive characteristics. These include the presence of epithelial downgrowth, eosinophilic infiltration, and epithelial solid and cystic implants. Although this information may be used to establish the diagnostic criteria for VKC as the cause of LSCD, further studies are needed to elucidate the reasons behind these unique findings.

BACKGROUND The aim is to study and compare supratarsal triamcinolone injection efficacy in respect to conventional modes of topical steroids & cyclosporine in cases of refractory VKC. MATERIALS AND METHODS 78 patients of refractory VKC were randomly distributed in 3 groups of 26 patients each. Topical difluprednate was given in group I, 0.4 mg triamcinolone acetonide was injected in supratarsal area in group II while 0.1% cyclosporine/Tacrolimus was given in Group III. RESULTS 51 (65%) were male while 27 (35%) were female with mean age group of 12.2 ± 3.5 years (Range-7 to 21 years). In group I, large papillae resolved in only 20 (77%) patients of the group while active shield ulcer resolved in 18 (69%) patients. In group II patients, large papillae and active shield ulcer showed marked improvement in 25 (97%) patients. There was significant difference as compared to topical steroids in respect to these signs. In group III patients, symptoms and signs improvement was less when compared to others. Recurrence was seen in both topical steroids and injectable triamcinolone after 3 months in almost 20-30% patients. In cyclosporine treated group, this was as high as 50-60% after 3 months. CONCLUSION Supratarsal injection has better patient compliance and significant improvement in signs over topical steroids although recurrence is almost similar. Prompt IOP monitoring is very important. Cyclosporine can be used in maintenance therapy because of its less side effects though its efficacy is far less than other 2 modes.