Limbal epithelial stem-microenvironmental alteration leads to pterygium development.

Maintenance of tissue homeostasis relies on the accurate regulation of tissue specific stem cell activity which is governed by the dynamic interaction between the positive and negative feedback modulating mechanism of stem cell microenvironmental niche. Alteration or deregulation of the "stem-microenvironmental networking" provokes disease development. Limbal epithelial stem cells (LESC) are the initiator hierarchy that maintains corneal integrity. Compartmentalization of LESC within the limbal vicinity provides an opportunity to understand the stem-microenvironmental relationship. The purpose of this study was to determine the microenvironmental alteration associated with LESCs fate in pterygium condition in comparison with healthy state. Clinical observations evaluated the ocular surface disorder with respect to corneal vascularization, tear film abnormality, and thickening of limbal area in pterygium patients. Structural alteration of limbal stem/progenitor cells and its neighboring niche components were observed using histology and scanning electron microscopy. Receptor overexpression of TGFß-R1, EGF-R1, and IL6-Rα and alteration of IL2-Rα expression pointed toward aberration of "stem-microenvironmental networking" in the limbal vicinity during disease development. Increased cell proliferation index along with TERT, Cyclin-D1, and PCNA over-expression in limbal part of pterygium epithelial cells indicated increased cellular proliferation and disturbed homeostatic equilibrium. We postulate that pterygium is associated with limbal microenvironmental anomaly where the resident epithelial cells became hyperproliferative.

Phenotypic alteration of limbal niche-associated limbal epithelial stem cell deficiency by ultraviolet-B exposure-induced phototoxicity in mice.

Good vision requires a healthy cornea, and a healthy cornea needs healthy stem cells. Limbal epithelial stem cells (LESCs) are a traditional source of corneal epithelial cells and are recruited for the continuous production of epithelium without seizing throughout an animal's life, which maintains corneal transparency. Like the maintenance of other adult somatic stem cells, the maintenance of LESCs depends on the specific microenvironmental niche in which they reside. The purpose of this study was to determine the microenvironmental damage associated with LESCs fate due to ultraviolet (UV)-B exposure in a mouse model. Structural alteration and deregulation of the stem cell and its neighboring niche components were observed by using clinical, morphological, explant culture study, and flowcytometric analysis, which demonstrated that the limbal microenvironment plays an important role in cornea-related disease development. In UV-exposed mice, overexpression of vascular endothelial growth factor receptor 2 indicated neovascularization, decreased CD38 expression signified the alteration of limbal epithelial superficial cells, and the loss of limbal stem cell marker p63 indicated limbal stem cell deficiency in the limbal vicinity. We concluded that LESC deficiency diseases (LESCDDs) are associated with pathophysiological changes in the LESC niche, with some inhibitory interception such as UV-B irradiation, which results in corneal defects.

Congenital distichiasis treated by a time-based cryosurgical technique--a case report.

Congenital distichiasis is a rare eyelid anomaly usually running in a family with some systemic disorders. Isolated congenital distichiasis is very rare. A very rare case of sporadic congenital distichiasis with symmetrical four-lid involvement is reported here. Detailed ophthalmic and systemic examinations failed to reveal any other abnormality. Various modalities of surgical techniques are tried to treat this difficult condition. It was treated by eyelid splitting and double freeze-thaw cryotherapy with anterior lamellar recession but no thermocouple was used. This simple modified technique, ensured excellent functional and cosmetic result with no recurrence in a one year follow-up.

Ocular surface disorder in pterygium: role of conjunctival impression cytology.

OBJECTIVE: To study ocular surface abnormalities in patients with pterygium, conjunctival impression cytology was explored as a tool for the assessment of the cytological changes. MATERIALS AND METHODS: A comparative case control study was undertaken to evaluate the ocular surface disorders in pterygium. Fifty cases of pterygium and 50 age and sex-matched controls were analyzed for the presence of local tear film abnormalities as assessed by the tear film break up time and Schirmer test. The spectrum of changes in cytomorphology was studied in detail using conjunctival imprint cytology. RESULTS: Tear film break-up time and Schirmer's strip wetting were found to be significantly different in study and control groups. Studying the cytomorphology of the conjunctival imprint smears, reduced cellularity and squamous metaplasia of different grades was observed more frequently in patients compared to controls. On overall grading of cytological changes, statistically significant difference was noted between the study and control groups (P value 0.00172). CONCLUSION: From the present study we can suggest that aqueous tear film deficiency leading to ocular surface disorder brings about a change at the cytological level, and ocular surface disorders found in pterygium can be interpreted by conjunctival impression cytology.

Sca-1 expression pattern in the mouse limbal epithelium and its association with cell cycle.

Stem Cell Antigen-1 or Sca-1 is a cell surface receptor protein commonly used to detect adult murine haematopoietic stem cell population. Outside the haematopoietic system Sca-1 is similarly expressed in stem and progenitor cells in a wide variety of tissues and organs such as skeletal muscle, mammary gland, prostate, heart, liver and dermis. Thus Sca-1 has become a candidate marker in the search of tissue specific stem cells. The maintenance of a healthy corneal epithelium is achieved by a unique population of stem cell located in the limbal epithelial region. This limbal epithelium mainly contains limbal epithelial stem cells and its immediate progenitor early transient amplifying cells (e-TAC) which have self renewal capacity. As stem cells in other organs have been identified by their expression of Sca-1, in our study we wanted to determine whether this antigen could be present in the limbal epithelial region which contains stem cell population by using immunofluorescence through flow cytometric analysis of Sca-1 and its association with the cell cycle.

Fine needle aspiration biopsy in the diagnosis of intraocular and extra-ocular mass lesions.

In a 3-year study with mass lesions related to ophthalmology 30 cases arising from ocular tissue, ocular adenaxae and orbit were subjected to fine needle aspiration biopsy. Of these 27 cases were further subjected to detailed histopathological examination. Fine needle aspiration biopsy revealed definitive cytological character in 23 cases consistent with histopathological and clinical diagnosis.

Vision screening programme among school children--evaluation of the outcome in a selected urban locality.

To determine the profile of the visual acuity status, refractive error and other ocular morbidities and to asses the performance at different stages following a vision screening programme in school a retrospective analysis of the data obtained from the programme register for school vision screening programme conducted from April 2003 to March 2006 was done. The data was plotted age and genderwise. Statistical analysis was done to find out disease prevalence with 95% confidence Interval and Z-test was applied for comparison. There were 45,087 students for 239 primary and secondary schools who were examined; 1856 students (4.11%) found having visual acuity .5 or less in either or both eyes. Refractive error was evident in 4.03% students and was the aetiology of compromised vision in 98%. Myopia topped the list with the prevalence of 2.85%; 1733 students (3.84%) were provided with spectacles. Correction of refractive error improved the visual disability in 3.93% of students while amblyopia was found in 0.10%. Average student load per teacher for initial screening was 229. The vision screening programme in school helps to detect refractive error and other causes of compromised vision among large section of children between 5 and 15 years age group. Use of correct spectacles prevents amblyopia considerably. Constraints arising in the programme can be removed by proper planning.

The profile of visual loss in children--a retrospective study in a referral hospital in India.

A retrospective study of 8772 children's records at the department of ophthalmology, North Bengal Medical College, Sushrutanagar, Darjeeling, West Bengal, India was conducted to collect the data on visual loss relating age, gender, degree and aetiology with an object of delineation of the profile of visual loss in children of particular area encircling that referral centre. Out of 8772 children, 126 children were detected to be suffering from visual loss. Of these 126 children, 88(69.84%) were males, 38(30.16%) were females, 75 children (59.52%) had low vision, 51(40.48%) had blindness. The causes of visual loss were cataract in 42 cases (33.33%), corneal pathology in 30(23.80%), high refractive error in 15(11.90%), glaucoma in 14(11.11%), retinal disease in 12(9.52%), global anomalies in 10 (7.94%) and lesion in the higher visual pathway in 3 cases (2.38%). Information obtained from the study possesses a definite role in understanding the background of visual loss in children of a particular area and planning the strategy to control childhood blindness by identification of preventable and treatable causes of blindness.