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Biomedical subjects

R C Arffa

Publications and source records attributed to R C Arffa.

27 records · Page 2Linked to original sources
PubMed1986

Rapid visualization of three common fungi using fluorescein-conjugated lectins.

The feasibility of using fluorescein-conjugated lectins to visualize and differentiate three fungi commonly involved in ophthalmic mycoses was evaluated. Using a panel of fluorescein-conjugated lectins, Candida albicans, Aspergillus fumigatus, and Fusarium solani were rapidly and reproducibly visualized in in vitro culture isolates, as well as in tissue samples and fixed histopathologic specimens taken from experimental mycoses. Additionally, Aspergillus and Fusarium were consistently differentiated from Candida. The binding affinities of the different lectins corresponded well with the individual sugar composition of the fungal cell walls.

Animals↗
PubMed1985

Calcofluor and ink-potassium hydroxide preparations for identifying fungi.

Calcofluor and ink-potassium hydroxide preparations identified Fusarium solani, Aspergillus fumigatus, and Candida albicans, the three most common ocular fungal pathogens, in scrapings, biopsy specimens, and tissue sections of corneal mycotic infections in rabbits. These stains also identified fungal organisms in specimens from four human patients with keratomycoses. Neither procedure requires more than a few minutes to perform or extensive training or experience to interpret. The specimen stained with calcofluor can be examined immediately, but may not identify all fungi. The more sensitive ink-potassium hydroxide preparation should be examined after 18 to 24 hours, and is less likely to provide false-positive results than the calcofluor method.

Animals↗
PubMed1985

Keratometric and refractive results of pediatric epikeratophakia.

Keratometric and refractive results of pediatric epikeratophakia showed that patients under 1 year of age had steeper corneas preoperatively and required more correction, as estimated by the Sanders-Retzlaff-Kraff regression formula. The average spherical equivalent of refractive error six months postoperatively was +6.92 +/- 4.67 diopters in patients under 1 year, and -0.72 +/- 4.22 D in patients over 1 year. Three of 14 younger patients and 35 of 54 older patients were within 3 D of emmetropia. Since March 1982, significant undercorrection has occurred only in patients 6 months old or younger. Younger children achieved an average of 46% of the predicted change in corneal curvature, while older children achieved 85%. Also, the Sanders-Retzlaff-Kraff formula may be inaccurate in estimating powers for younger children. Therefore, we recommend at this time that epikeratophakia be used as a secondary procedure in neonates with congenital cataracts.

Age Factors↗
PubMed1984

Chorioretinal scars in Fuchs' heterochromic iridocyclitis.

To determine the incidence of chorioretinal lesions in patients with Fuchs' heterochromic iridocyclitis, we reviewed the records of all patients with this disease seen at the Indiana University Uveitis Service, Indianapolis, since 1963. For comparison the records of age- and sex-matched patients with HLA-B27-positive iritis were also reviewed. The incidence of chorioretinal lesions in one or both eyes of patients with Fuchs' heterochromic iridocyclitis was significantly higher than in the patients with HLA-B27-positive iritis or than expected in the general population. Among the types of lesions manifested, the most notable increase was in toxoplasmosislike lesions. However, two of the five patients with these lesions had negative indirect hemagglutination assays for toxoplasmosis, down to undiluted serum. The reason for the high incidence of chorioretinal lesions in patients with Fuchs' heterochromic iridocyclitis is unclear and may be related to immunologic changes in these patients.

Adolescent↗
PubMedDate not supplied

Peripheral corneal disorders.

The peripheral cornea is anatomically and physiologically distinct from its central counterpart. The major differences relate to the gradual transition of corneal tissues to those of the conjunctiva, episclera, and sclera; furthermore, the vascular structures, lymphatics, and inflammatory cells from these neighboring structures are intimately associated with the limbus and periphery of the cornea. The peripheral cornea is thereby predisposed to three main classes of disorders which do not normally involve the central cornea. First, local conditions affecting the sclera and conjunctiva may secondarily spread to involve the limbus and peripheral cornea. These include several infectious diseases, as well as hypersensitivity conditions, mass lesions, and degenerations. Second, due to the associated blood vessels and lymphatics, the peripheral cornea may be involved in a variety of systemic diseases, including vasculitides, autoimmune disorders, and abnormal metabolic conditions. Finally, there are several conditions, such as the noninflammatory peripheral degenerations, which primarily affect the peripheral cornea without associated ocular or systemic changes. In this review, we present a classification and discussion of the various disorders which may involve the peripheral cornea.

Aging↗
PubMedDate not supplied

Epikeratophakia in children with traumatic cataracts.

Epikeratophakia provides a permanent optical correction for aphakia in children with congenital or traumatic cataracts; suturing the epikeratophakia graft onto the cornea eliminates the problems of contact lens or spectacle non-compliance in these young and generally uncooperative patients and provides tectonic support to scarred and irregular corneas. Eighteen children under the age of six years underwent epikeratophakia for the correction of aphakia after the removal of trauma-induced cataracts. Graft success rate was 88%; the average change in keratometry in the patients with successful grafts was 14.82 +/- 2.0 diopters. In the 13 patients eligible for visual acuity tabulation, preoperative acuities ranged from light perception to 20/200, and postoperative acuities ranged from hand motions to 20/30. Ten (77%) had acuities of 20/80 or better. Poor results in three patients with less than 20/200 acuities were likely the results of non-compliance with amblyopia therapy. Present work indicates that in cases of traumatic cataract, the epikeratophakia procedure facilitates amblyopia therapy and decreases the astigmatism in scarred and irregular corneas.

Cataract↗
PubMedDate not supplied

Attachment of cultured corneal epithelial sheets to epikeratophakia lenticules.

Tissue lenses for epikeratophakia are currently prepared by one of three different methods: cryolathing and storage in corneal preservation media; cryolathing and lyophilization; or non-freeze microkeratome cutting. It has been proposed that avoidance of the damage caused by freezing or lyophilization will speed healing and recovery of vision. We examined the ability of epithelium to attach to lenses produced in each of the three ways. Human donor corneal epithelium was cultured, and multiple continuous sheets were obtained from each donor eye. Eighteen lenses were prepared by one of the three methods above, and a cultured epithelial sheet was placed on each lens. The percentage of the surface area covered with epithelium and the number of cell layers were determined 24 or 72 hours later. An average of 92% of the lens surface was epithelialized at 24 hours, and 89% was epithelialized at 72 hours. The average number of cell layers was 1.6 at 24 hours and 2.5 at 72 hours, a significant difference. The cryolathed, non-lyophilized lenses showed the lowest percentage of surface area covered, and this was statistically significant at 72 hours.

Cell Adhesion↗
PubMedDate not supplied

Corneal topography using rasterstereography.

Rasterstereography is a new method of determining the topography of the cornea. Unlike Placido disc types of systems it does not depend on the reflectivity of the corneal surface, and it can provide information about the entire corneal, limbal and interpalpebral conjunctival surfaces. Since a smooth reflective surface is not required, images can be obtained with epithelial irregularity or defects, sutures, or stromal ulceration. A grid of horizontal and vertical bars of light is projected onto the cornea, and the pattern of the grid on the ocular surface is determined by its topography. The image is obtained by a video camera, and digitized, stored, and analyzed by an image processor. A three dimensional image of the corneal surface, contour maps of corneal elevation, and corneal curvature can be displayed.

Cornea↗