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Results for “Limbus Corneae”

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At least 19 recordsLinked to original sources
PubMed1978

Fluorescein angiography of the corneal limbus--drug effects on capillary blood flow.

By means of fluorescein angiography, plasma flow through the capillaries at the limbus corneae is demonstrated. The number of stained capillaries at a given time served as a measure of capillary perfusion. Even without drug the entire capillary system is perfused at least by plasma. Tolazoline enhanced the velocity of perfusion (P = 2alpha less than 0.01), epinephrine caused a marked capillary constriction (P = 2alpha less than 0.01), as well as--to a lesser extent--did dexamethasone (P = 2alpha less than 0.05). Dionine caused hyperemia, but the data varied much more than after tolazoline. In addition, dionine enhanced the dye leakage from the vessels.

Adult↗
PubMed1977

[Modification of the microsurgical closure of the incision in cryosurgery for cataract (author's transl)].

In this paper a microsurgical technique for cataract operation is discussed which displaces the whole healing process of the operation wound from the sensitive region of the limbus corneae to the easily and quickly healing connective tissue of the sclera. The modified procedure for microsurgical closure of the wound is also treated in detail, which depends on the fact scleral flaps are apposed to an appropriate fixation band formed from the scleral tissue.

Cataract Extraction↗
PubMed1979

Expression of Ia antigen-like molecules on cells in the corneal epithelium.

Ia antigens, known to be expressed preferentially on cells of the immune system, have been shown to be present on cells in the cornea. By immunofluorescence studies, it was shown that a specific rabbit anti-Ia antigen serum stained cells in the corneal epithelium. The stained cells were well integrated into the corneal epithelial architecture and displayed short dendritic processes. Their location in the cornea and corneal limbus and their morphological appearance make it reasonable to suggest that the Ia antigen-expressing cells of the cornea are equivalents of the Ia antigen-bearing Langerhans' cells of the epidermis.

Animals↗
PubMed2017

Genome-wide analysis suggests a differential microRNA signature associated with normal and diabetic human corneal limbus.

Small non-coding RNAs, in particular microRNAs (miRNAs), regulate fine-tuning of gene expression and can impact a wide range of biological processes. However, their roles in normal and diseased limbal epithelial stem cells (LESC) remain unknown. Using deep sequencing analysis, we investigated miRNA expression profiles in central and limbal regions of normal and diabetic human corneas. We identified differentially expressed miRNAs in limbus vs. central cornea in normal and diabetic (DM) corneas including both type 1 (T1DM/IDDM) and type 2 (T2DM/NIDDM) diabetes. Some miRNAs such as miR-10b that was upregulated in limbus vs. central cornea and in diabetic vs. normal limbus also showed significant increase in T1DM vs. T2DM limbus. Overexpression of miR-10b increased Ki-67 staining in human organ-cultured corneas and proliferation rate in cultured corneal epithelial cells. MiR-10b transfected human organ-cultured corneas showed downregulation of PAX6 and DKK1 and upregulation of keratin 17 protein expression levels. In summary, we report for the first time differential miRNA signatures of T1DM and T2DM corneal limbus harboring LESC and show that miR-10b could be involved in the LESC maintenance and/or their early differentiation. Furthermore, miR-10b upregulation may be an important mechanism of corneal diabetic alterations especially in the T1DM patients.

Adult↗
PubMed1979

Molluscum contagiosum of the palpebral conjunctiva. Report of a case.

A molluscum contagiosum nodule, situated at the palpebral conjunctiva of the left lower eyelid at the level of the marginal and tarsal conjunctiva, was observed in a 53-year-old male. A mild follicular conjunctivitis was present, except in a zone immediately below the molluscum. On the corresponding site of this molluscum at the bulbar conjunctiva, the limbus and the cornea, no follicles, epithelial keratitis nor erosions were seen. Clinical diagnosis in atypically situated mollusca can be difficult. Cytological studies in these cases are very helpful. Alcohol-carbowax fixated and Papanicolau stained preparations proved to be very satisfactory for cytological examination. It has never been reported that a molluscum, situated in the palpebral conjunctiva, disappeared spontaneously.

Conjunctiva↗
PubMed1978

Blood flow in rabbit eyes after keratectomy and corneal transplantation.

We used radio-labelled microspheres to study the distribution of blood flow in different regions of rabbit eyes with inflamed corneas resulting from trauma or allograft reaction. The blood flow in the cornea, the anterior uvea and the regional lymph nodes draining it was increased, but total flow in the eye did not increase. More blood went to the anterior uvea at the expense of the rest of the eye. Blood flow at the limbus was higher in the inflamed corneas than in the controls.

Animals↗
PubMed1979

Histological and electron microscopic studies of experimental herpetic keratitis in the rabbit.

Histological and electron microscopic observations, together with virus cultures, were made in the eyes of 50 New Zealand white rabbits which received bilateral intrastromal inoculation with the RE strain of herpes simplex virus. Virus cultures of whole corneas were positive for the first 2 weeks following inoculation, but were consisently negative thereafter. An inflammatory response to HSV infection, consisting of polymorphonuclear leukocytes and lymphocytes, was seen in the limbus within 7 hours after inoculation of the cornea. A massive accumulation of lymphocytes and plasma cells appeared in the limbus, suggesting that the limbus may behave as a lymphoid tissue, where differentiation and maturation of lymphoid cells occur as they acquire immunocompetence. Neovascularization of the cornea was associated with a heavy infiltration of the surrounding stroma with polymorphonuclear leukocytes, as well as numerous plasma cells and a few lymphocytes and macrophages. Numerous abnormal, pleomorphic keratocytes were found in the stroma. Lymphocytes were frequently found closely adhering to these abnormal keratocytes, suggesting a T-cell attack on a target cell. A model which describes the mechanism by which herpes virus infection leads to corneal scarring is suggested.

Animals↗
PubMed1978

Biochemical and histochemical response to a complete epithelial denudation of the rabbit cornea. Alkaline and acid phosphatase.

Activities of alkaline and acid phosphates were investigated in rabbit corneas after a complete epithelial denudation in vivo (limbus to limbus). Dynamics of enzymatic changes during corneal healing were followed quantitatively in homogenates of regenerated epithelium and stroma (denuded cornea) and in cryostate frozen sections on days 1, 4, 7, 14, and 28. Biochemical and histochemical findings at these times showed a different response in each enzyme. Acid phosphatase displayed a gradual increase of activity in epithelium as well as in stroma; on day 28 after injury its content was normal. In contrast, alkaline phosphatase showed delayed activity during the repair process, and even a month after de-epithelization was still subnormal, particularly in superficial layers of epithelium.

Acid Phosphatase↗
PubMed1979

[The artificial epithelium in chronic corneal diseases and to avoid emergency keratoplasty (author's transl)].

Report on the treatment of 41 patients in the last 10 years. In chronic corneal diseases epikeratoprosthesis is possible when every other therapy failed. With growing experience functional results are better and complications seldom. Since several years we use glued-on contact lenses in acute ulcers too in order to avoid emergency keratoplasty. When suitable donor material is missing or if plastic surgery of the eye lids is necessary the artificial epithelium prevents ulcer perforation as a mechanical collagenase inhibitor. The anterior chamber can be reinstalled in perforated ulcers by sealing with cyanoacrylate glue and covering with artificial epithelium. A corticosteroid therapy of the iritis becomes possible to avoid the frequent complication of anterior synechia in later keratoplasty. By reducing the steroid dosis vascularisation of the ulcer is reached and a corneal grafting can be evaded sometimes if the prognosis of keratoplasty is poor or the central cornea is clear such as in ulcers near the limbus.

Adrenal Cortex Hormones↗
PubMed1976

Experimental disciform edema and necrotizing keratitis in the rabbit.

The development of experimental disciform edema and necrotizing keratitis in the corneas or rabbits following intrastromal inoculation with the RE strain of herpes simplex virus is described. Following an initial episode of conjunctivitis and epithelial keratitis, a mild, centrally localized, stromal edema developed on the fifth day. Stromal edema, opcification, and neovascularization of the cornea reached maximum severity on the seventh to twenty-second day, and began to fade in most eyes thereafter. On the twenty-ninth day most corneas have attained a resolved state characterized by subepithelial granular opacities. Several eyes were observed which developed central necrotizing keratitis. Marked similarities between the animal model and human herpetic stromal keratitis were apparent. Histological observations show that early necrotizing keratitis in the rabbit is characterized by an infiltration of plasma cells and lymphocytes in the limbus, with polymorphonuclear leukocytes, lymphocytes, and macrophages in the central cornea.

Animals↗
PubMed1979

The dynamics of IgG in the cornea.

Fluoresceinated IgG was injected centrally into the rabbit's cornea and both its rate of loss from the tissue and its rate of spread in the stroma were estimated by objective fluorometry. A new technique for determining the rate of loss was established which required only the measurement of the maximum fluorescence in the tissue. The rate at which freshly formed IgG in the blood would arrive at the central regions of the cornea was estimated for the human eye. As penetration continues from the limbus and the protein is lost to the aqueous humor, a standing concentration gradient is set up with a minimum at the corneal center. Calculation suggests that this gradient should be small for IgG in the human eye.

Animals↗
PubMed1978

Pellucid marginal corneal degeneration.

Pellucid marginal degeneration of the cornea is a bilateral, clear, inferior, peripheral corneal-thinning disorder. Protrusion of the cornea occurs above a band of thinning, which is located 1 to 2 mm from the limbus and measures 1 to 2 mm in width. American ophthalmologists are generally not familiar with the condition because most of the literature concerning pellucid degeneration is European. Four cases are described. This condition is differentiated from other noninflammatory cornel-thinning disorders such as keratoconus, keratoglobus, keratotorus, and posterior keratoconus. It is also differentiated from peripheral corneal disorders associated with inflammation such as Terrien's peripheral corneal degeneration, Mooren's ulcers, and ulcers from connective tissue disease.

Adult↗
PubMed1979

Wedge resection in host cornea to correct post-keratoplasty astigmatism.

The obvious problem with surgery of this nature is that the amount of wedge to be removed is partially guess work. Doctor Troutman's keratoscope attachment to his microscope is very helpful. I have tried thermokeratoplasty in a very similar case, but the disadvantages of pain, ulceration, vascularization, and considerable return to pre-burn K readings have made me abandon this technique. If there is an obvious override, then the keratoplasty wound itself must be revised in the usual manner. However, for the present, when a graft looks perfect but the K readings reveal otherwise, a judicious wedge resection between graft and limbus (location being in the flattest meridian) would appear to be a most reasonable operation.

Astigmatism↗
PubMedDate not supplied

Immunology of herpesvirus infection: immunity to herpes simplex virus in eye infections.

A gereral, overall pattern of the temporal relationship and interaction between cell and antibody-mediated immune responses following herpes simplex virus infection of the rabbit cornea can be synthesized from our studies. Cell-mediated immunity (CMI) appears early following infection, at a time when mononuclear and lymphocytic cellular proliferation occur at the limbus. Interaction between specifically immune lymphocytes with virus antigens are detected by lymphocyte blastogenesis and migration inhabiting factor. During stromal keratitis, a second phase of CMI involves transient virus-specific cytotoxic lymphocytes, which destroy cells that display viral-induced antigens on their surface. Chemotatic factors generated by viral antigens alone or with antiviral antibody or by virus-sensitized lymphocytes play a role in attracting polymorphonuclear leukocytes to the cornea during stromal keratitis. Soluble mediators of CMI secreated by activated lymphocytes act both specifically and nonspecifically on virus-infected cells, allowing cell destruction and making intracellular virus available for neutralization by antiviral antibody. Cell-mediated immunity in the acute infection, diminishes with the appearance of significant antiviral antibody titers. The late phase of the corneal immune response results from a local antigen-antibody interaction and is characterized by cells predominantly of the plasmacytic type. The presence of complement-dependent cytotoxic antibodies capable of destroying virus-infected cells provide an additional factor in restriction of infection.

Animals↗
PubMed1979

Anterior segment fluorescein angiography in inflammatory diseases of the cornea.

To study the vascular changes in inflammatory diseases of the cornea 22 patients with various corneal inflammations were examined by means of anterior segment fluorescein angiography. Simple avascular central and marginal corneal ulcers stained with fluorescein in the late phase of angiography. An inflamed limbus and an early microscopic pannus adjacent to the ulcer were seeen in simple corneal ulcers. Progressive pannus with pronounced fluorescein leakage was observed in chronic corneal ulcer, disciform keratitis, Mooren's ulcer, and complicated acute keratoconus. In sclerokeratouveitis and in gutter associated with rheumatoid arthritis the corneal vessels showed less leakage. The iris vessels showed fluorescein leakage as a sign of irritative iritis during the active stage of simple and chronic corneal ulcers, in disciform keratitis, Mooren's ulcer, and in graft rejection. It is concluded that anterior segment fluorescein angiography gives valuable information of the vascular architecture, flow and leakage in inflammatory diseases of the cornea.

Adult↗
PubMed1978

[Corneal changes in patients on dialysis for renal failure (author's transl)].

The corneas of 100 patients on dialysis for renal failure were observed. In 52 patients follow up studies were possible. 55 patients demonstrated limbal changes. On slit lamp biomicroscopy these changes showed to be similar to the white limbus girdle described by Vogt. Small limbal biopsies from five patients on dialysis were studies histopathologically and compared to biopsies from three patients with normal renal function. Only patients on dialysis showed senile elastosis and three of them epithelial and subepithelial hyaline deposits. Calcium deposition was the same in both groups.

Adolescent↗