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Biomedical subjects

R A Hyndiuk

Publications and source records attributed to R A Hyndiuk.

At least 19 recordsLinked to original sources
PubMed1992

Blastomycosis of the eyelid and conjunctiva.

A 37-year-old man with a recurrent papillomatous lesion of the upper eyelid and four separate bulbar conjunctival ulcers was found to have North American blastomycosis. This represents the first reported case with conjunctival lesions that were not simply contiguous with eyelid involvement. This case underscores the importance of considering blastomycosis in the differential diagnosis of granulomatous conjunctivitis and when examining a lesion of the eyelid resembling a squamous cell carcinoma or atypical papilloma.

Adult↗
PubMed1992

Overview of the corneal toxicity of surgical solutions and drugs: and clinical concepts in corneal edema.

Surgical solutions and drugs are important in ocular surgery. These include irrigating solutions, viscoelastic substances, mydriatics and miotics, and a growing number of other agents designed to enhance intraocular surgery and its outcome. Potential for damage to the corneal endothelium and other tissues is related to the chemical composition, pH, and osmolality of the irrigating solutions that bathe tissues. Quality balanced salt solutions (BSS) are usually safe for use as an intraocular solution in patients with normal corneal endothelium. If prolonged irrigation times are expected, or the patient already has decompensated endothelium, i.e., primary or secondary endotheliopathy, the use of a "complete" BSS solution is indicated to minimize damage. Intraocular sulfite-containing epinephrine may cause severe corneal edema and should be avoided, or if used, be well diluted. Sulfite-free epinephrine solution is now available and does not cause the endothelial toxicity that one may see with sulfite-containing epinephrine solutions. Current formulations of acetylcholine and carbachol used as miotics in surgery have been evaluated in humans and caution is recommended in using acetylcholine solutions intracamerally in patients with already decompensated endothelium. Chondroitin sulfate, hydroxypropyl methylcellulose, and sodium hyaluronate are non-toxic to animal endothelial cells under conditions analogous to cataract extraction in humans but can be toxic to endothelium if there is continued contact with endothelium for hours. Chondroitin sulfate has been shown to have more of a protective effect in mechanical pseudophakos trauma probably because of its cohesiveness and tendency to coat the endothelium. Viscoelastics cause a significant rise in intraocular pressure of > 30 mm Hg in 3-10% of patients. Very high intraocular pressures are often seen postoperatively after viscoelastic use surgically in patients who preoperatively have a history of ocular hypertension or glaucoma.

Cell Count↗
PubMed1992

The role of viscoelastics, cannulas, and irrigating solution additives in post-cataract surgery corneal edema: a brief review.

Corneal clarity is dependent upon maintenance of the corneal endothelial barrier and pump. Mechanical trauma is usually considered to be the most significant factor in corneal endothelial damage during cataract surgery resulting in postoperative corneal edema. However, corneal decompensation out of proportion to the degree of trauma seen during surgery does occur. These cases of unexpected corneal edema can often be traced to unrecognized preoperative endothelial dysfunction or to toxicity of intraocular medications used during surgery. This paper reviews the role of viscoelastics in reducing surgical trauma, their toxicity, and the risks of toxicity inherent in the use of re-usable cannulas and irrigating solution additives. Disposable cannulas should be used whenever possible. The use of re-usable cannulas with viscoelastics is highly likely to result in toxic residues being introduced onto the eye, and must be avoided. Irrigating solution additives should be tested with in-vitro human donor cornea perfusions prior to clinical use.

Cataract Extraction↗
PubMed1992

Infectious conjunctivitis.

This article is designed to aid the clinician in the diagnosis of bacterial and viral conjunctivitis by evaluating a wide variety of infectious causes of conjunctivitis. The work-up, including techniques of examination and pertinent laboratory studies, is discussed. Clinical features of each type are covered at length and specific therapy for each is included.

AIDS-Related Opportunistic Infections↗
PubMed1991

Insights from experimental data on ciprofloxacin in the treatment of bacterial keratitis and ocular infections.

Ciprofloxacin is a potent fluoroquinolone antibiotic with in vitro activity against many significant gram-positive and gram-negative ocular pathogens. A review of the experimental studies of this antibiotic shows bactericidal activity, a broad antimicrobial spectrum, and a low incidence of resistance. The growing body of experimental data supports the effectiveness of ciprofloxacin in the treatment of experimental keratitis and suggest that it be evaluated further in ocular infections.

Bacterial Infections↗
PubMed1990

Efficacy and safety of mercuric oxide in the treatment of bacterial blepharitis.

A double-masked, placebo-controlled, randomized study was done to assess the safety and clinical and quantitative microbiologic efficacy of 1% mercuric oxide (yellow) ophthalmic ointment in the treatment of eyelid infections, i.e., bacterial blepharitis. A total of 39 patients with bacterial counts and clinical signs indicative of eyelid infection were treated twice daily for 7 days. Clinical biomicroscopic examination and quantitative microbiologic cultures were done just prior to initiation of treatment and again on days 3 and 7. Statistical analysis revealed a significant improvement in the clinical signs, bacterial count, cure rate, and improvement rate for subjects taking the active medication, compared with those taking the placebo on days 3 and 7. In addition, the medication was well tolerated.

Adult↗
PubMed1989

Penetrating keratoplasty and intraocular lens exchange for pseudophakic bullous keratopathy associated with a closed-loop anterior chamber intraocular lens.

We reviewed the records of 20 consecutive eyes with pseudophakic bullous keratopathy associated with a closed-loop anterior chamber lens that underwent penetrating keratoplasty, total anterior vitrectomy, and anterior chamber intraocular lens exchange. On reexamination, all corneal grafts had remained clear during an average follow-up period of 15 months (range, four to 45 months). Seven eyes (35%) attained a visual acuity of 20/40 or better with spectacle correction; however, 15 of 20 eyes (75%) attained a best-corrected visual acuity of 20/40 or better using a pinhole and a gas-permeable contact lens. In five eyes visual acuity was 20/400 or poorer because of cystoid macular edema, as documented by fluorescein angiography, age-related macular degeneration, or optic atrophy. Localized, minimal peripheral anterior synechiae were present on gonioscopy in seven eyes. The one-piece flexible anterior chamber lens implants used for exchange appeared to be well tolerated in this series of patients.

Aged↗
PubMed1989

Filter-culture technique using amoeba saline transport medium for the noninvasive diagnosis of Acanthamoeba keratitis.

Acanthamoeba, a common free-living amoeba, is increasingly incriminated as a cause of keratitis and corneal ulceration. Between March 1986 and July 1988, specimens from seven patients submitted by ophthalmologists to the City of Milwaukee Health Department's Bureau of Laboratories were culture positive for Acanthamoeba. All patients were contact lens wearers. The specimens were transported at ambient temperature in amoebasaline (5.0 mL) and filtered through 13 mm 0.22 microns cellulose filters. The filters were then plated in cocultivation with Escherichia coli on nonnutrient agar and had positive results for Acanthamoeba in two to five days. Contact lens cases were culture positive for Acanthamoeba in three instances. These results indicate that corneal scraping in amoeba saline transport medium can provide an effective way to diagnose Acanthamoeba keratitis when direct culture of such specimens is not possible.

Acanthamoeba↗
PubMed1988

Fortified antibiotic ointment in bacterial keratitis.

We conducted experiments to determine the effectiveness of fortified antibiotic ointment in the treatment of Pseudomonas keratitis in rabbits. We evaluated gentamicin ointment (3, 10, 20, and 40 mg/g), gentamicin solution (3 and 10 mg/ml), and placebo, each given every 30 minutes. We also examined the effectiveness of fortified ointment given in extended treatment intervals. In short-term trials, commercial-strength gentamicin solution (3 mg/ml) was therapeutically superior (P less than .001) to commercial-strength gentamicin ointment (3 mg/g) in reducing corneal bacterial colony counts. No significant difference in antimicrobial effect was noted between fortified gentamicin ointment and fortified gentamicin solution at 30-minute treatment intervals. Fortified gentamicin ointment reduced colony counts even at extended treatment intervals of up to four hours in a severe keratitis model.

Animals↗
PubMed1986

Relationship between proteases and descemetocele formation in experimental Pseudomonas keratitis.

Proteases are involved in the pathogenesis of Pseudomonas aeruginosa infections of the cornea. Although there are many potential roles for these enzymes, involvement in corneal stroma destruction with subsequent descemetocele formation and/or corneal perforation is an important example. This study examined the relationship of elastase and alkaline protease to corneal destruction as indicated by descemetocele formation. The protease content of the overnight Mueller-Hinton broth cultures of various strains of P. aeruginosa correlated with the production of descemetoceles both in the rabbit trauma model of Pseudomonas keratitis and upon intrastromal injection of filtrates of the overnight culture media. The levels of alkaline protease correlated better with descemetocele formation than those of elastase. The influx of inflammatory cells was not correlated with descemetocele formation within 24 to 48 hrs.

Animals↗
PubMed1986

Role of leukocytes in ocular inflammation of tyrosinemia II.

In the animal model of tyrosinemia II only corneas from tyrosine(tyr)-fed rats produce chemoattractants in organ culture. To study the role of neutrophils (PMNs) in production of these chemoattractants, leukocytes (WBCs) were depleted using i.p. cyclophosphamide (CP). Saline (SAL)-treated rats maintained 18,375 +/- 894 WBC/mm3 (mean +/- SEM) with 4168 +/- 424 PMNs. Rats receiving CP (150 mg/kg day 0, 75 mg/kg day 4) has 1565 +/- 170 WBC (565 +/- 129 PMN) on day 3, and 398 +/- 68 WBC (19 +/- 5 PMN) on day 8. Rats ate a low-protein +/- 5% tyr diet on days 4-8. Only SAL-treated tyr-fed rats developed plaque-like gray epithelial lesions; histopathology showed corneal epithelial necrosis, stromal edema, and epithelial and stromal PMN infiltration. Control and CP-treated tyr-fed rat corneas showed no inflammation. On day 8 corneas were cultured in RPMI 1640 + 5% heat-inactivated fetal bovine serum. After 3 days, supernatants were assayed for chemotactic activity (leading front method); data were expressed as the percentage of peritoneal PMN migration relative to 5% zymosan-activated rat serum. The mean total migration toward 75% supernatant from SAL-treated, tyr-fed rat corneas was 79%, whereas migration toward corneal supernatants from controls and CP-treated tyr-fed rats ranged from 42-48%. Corneal extracts were assayed for proteolytic activity. WBC depletion prevented the increase in cathepsin B- and D-like activities present in tyr-fed corneas, suggesting that PMNs were a major source of these enzymes. The data suggest that WBC depletion reduces both corneal inflammation in vivo and the production of chemotactic activity by tyr-fed corneas in culture.

Animals↗
PubMed1985

Corneal organ cultures in tyrosinemia release chemotactic factors.

Corneal inflammation with subsequent scarring and blindness occurs in the inherited human metabolic disease tyrosinemia type II, yet putative inflammatory mediators in this disorder and in the avascular cornea in general are poorly defined. In a Tyr-fed rat model of tyrosinemia type II, intracellular crystals, presumably Tyr, are hypothesized to be responsible for the increased lysosomal activity observed in corneal epithelial lesions. Because polymorphonuclear leukocytes (PMNs) are seen only at the site of these lesions, we used this model to study humoral mediators released from Tyr-fed rat corneal organ cultures. Only Tyr-fed rats developed stromal edema and linear granular opacities in gray edematous corneal epithelium, compatible with a noninfectious keratitis. Electron micrographs confirmed epithelial edema and showed focal epithelial necrosis with PMN invasion of the stroma. Only Tyr-fed rat corneal culture supernatants contained chemotactic activity that was heat labile and moderately trypsin sensitive. Four peaks with varying amounts of chemotactic activity were found on Sephadex G-75 chromatography. Although the identity of these peaks of activity has not yet been established, we suggest that they may be responsible for the PMN infiltration observed in this model of corneal inflammation.

Amino Acid Metabolism, Inborn Errors↗
PubMed1985

Acid proteases and histologic correlations in experimental ulceration in vitamin A deficient rabbit corneas.

Although xerophthalmia due to severe vitamin A deficiency is the leading cause of childhood blindness in the underdeveloped countries, little is known about the proteases (other than collagenase) that are involved in the degradative mechanism. The degree of cellular autolysis and stromal degradation observed histologically in early stages of xerophthalmia and in ulcerating corneas in vitamin A deficient rabbits in this study were, in general, proportional to the levels of the proteases studied. The only major histologic and ultrastructural alteration observed in early xerophthalmic corneas was autolysis of superficial epithelial and stromal cells. In contrast, in the ulcerating corneas the stroma was infiltrated heavily with inflammatory cells and extensive stromal degradation was observed in the central necrotic region of the lesions. Maximal proteolytic activity toward hemoglobin was observed at pH 3.3 for corneal extracts from normal (N) and pair-fed control (C) rabbits and rabbits with early xerophthalmia (X) and ulcerating xerophthalmia (U) corneas. This activity was a cathepsin D-like enzyme per cornea that had a ratio of 1:1:3:16 in the N, C, X, and U corneas. The ratio of cathepsin B-like activity per cornea for N, C, X, and U corneas was 1:2:2:10.

Animals↗
PubMed1984

Fluorometholone acetate: clinical evaluation in the treatment of external ocular inflammation.

Separate, randomized, double-masked clinical studies were conducted to determine the therapeutic efficacy of fluorometholone acetate, a new ophthalmic corticosteroid formulation, in suppressing external ocular inflammation (conjunctivitis, episcleritis, scleritis). Fluorometholone acetate 0.1% was compared to fluorometholone 0.1%, and the acetate formulation was found to be significantly (p = 0.03) more effective. Fluorometholone acetate 0.1% also was compared to prednisolone acetate 1.0%; there was no significant difference (p = 0.49) between these two corticosteroids in their ability to suppress external ocular inflammation. It appears that alteration of fluorometholone from its alcohol base to its acetate derivative changes the drug from a moderately effective to a highly effective anti-inflammatory agent.

Adult↗