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Biomedical subjects

L D Ormerod

Publications and source records attributed to L D Ormerod.

At least 37 records · Page 2Linked to original sources
PubMed1991

Infectious crystalline keratopathy. Role of nutritionally variant streptococci and other bacterial factors.

Infectious crystalline keratopathy (ICK) is a chronic corneal infection characterized by interlamellar plaques of gram-positive coccal bacteria in the absence of inflammatory cells. It generally occurs within a corneal graft. Viridans streptococci are usually isolated, but the clinical response to antibiotics is poor and disparate with the in vitro antimicrobial sensitivities. These features suggest the possibility of unusual bacterial factors in pathogenesis. Four cases caused by nutritionally variant viridans streptococci are described. The organisms were fully characterized. They have a rare nutritional requirement for pyridoxal and require defined culture conditions and specific identification. Nutritional variant streptococci (NVS) are principally described as causing endocarditis, another infection involving an avascular collagenous tissue, and exhibiting similar biologic behavior. Electronmicrographic evidence is also adduced that suggests the possible importance of intracorneal glycocalyx deposition. Such factors might explain the anomalous clinical characteristics of this condition.

Adult↗
PubMed1990

Anterior segment fluorescein videoangiography with a scanning angiographic microscope.

The scanning laser ophthalmoscope can be modified to operate as a scanning laser biomicroscope for use in anterior segment fluorescein angiography. The substantial depth of focus, large field of view, co-axial illumination, low light levels, real-time television operation, and videorecording with immediate recall provide advantages not available with conventional photographic methods. Video techniques give a resolution slightly inferior to photography, but this is unlikely to be significant in clinical practice. A technique of traversing the entire anterior episcleral vasculature has been developed to give a comprehensive and reproducible angiographic record. Previous fluorescein studies suggesting the primary importance of retrograde (centrifugal) flow in the perforating anterior ciliary arteries were not supported; methodologic explanations are advanced. Several principles are proposed to improve techniques of anterior segment angiography.

Adult↗
PubMed1990

Effects of altering the eicosanoid precursor pool on neovascularization and inflammation in the alkali-burned rabbit cornea.

The effects of altering the eicosanoid precursor pool on several aspects of the nonimmunologically mediated inflammatory and angiogenic processes that follow 1N and 4N NaOH alkali burning of the rabbit cornea were compared with controls. Diets were supplemented with several dosages of oils containing either gamma-linolenic acid (GLA) (borage oil), eicosapentaenoic acid (EPA) (sardine oil), or a combination of the two in a dose-response protocol. Significant changes in serum fatty acid composition were demonstrated. Gamma-linolenic acid proved consistently superior to EPA in modulating the neovascular response judged by three neovascular indices. At 14 days, GLA significantly reduced the polymorphonuclear leukocyte and macrophage inflammatory infiltrate and EPA reduced the macrophage component, both with high dose; EPA also reduced keratocyte proliferation. Wound-healing parameters were unaffected. Evidence for GLA-EPA synergism was modest. Prolonged neovascular responses and chronic inflammation occurring in the clinically relevant context of severe structural damage can be modulated by nutritional alteration of the eicosanoid precursor pool.

Animals↗
PubMed1989

Severe group B streptococcal eye infections in adults.

Group B beta-haemolytic streptococci have not been described as causing invasive eye infection in adults. Our observation of 10 such infections in nine patients indicates that persons with damaged ocular surfaces are especially vulnerable.

Aged↗
PubMed1989

Prospective, randomized trial of oral piroxicam in the prophylaxis of postoperative cystoid macular edema.

One hundred and seventy-eight patients undergoing uncomplicated cataract extraction with posterior chamber intraocular lens insertion completed a prospective, randomized, controlled trial of oral piroxicam in the prophylaxis of postoperative cystoid macular edema (CME), with a 1-year follow up. The incidence of "visually significant" CME, the mean interval to onset following surgery, clinical severity, recurrence rate, and the time to achieve best corrected visual result were unaffected by a 17-day piroxicam course. Oral steroid CME treatment produced a rapid response, but could not be shown to change the ultimate visual results. High-performance liquid chromatography analysis of aqueous humor obtained at cataract surgery suggested that piroxicam's pharmacokinetics might be a factor in this lack of response; the large number of potential inflammatory mediators uninfluenced by cyclo-oxygenase inhibition also may implicate piroxicam pharmacodynamics.

Administration, Oral↗
PubMed1989

Standard models of corneal injury using alkali-immersed filter discs.

Central corneal alkali burn injuries were induced in rabbits by applying five NaOH concentrations on uniformly soaked 7 mm filter paper discs. Clinical parameters were evaluated daily by microscopic examination and photography, and corneal myeloperoxidase levels were measured periodically. Satisfactory alkali burn models of corneal inflammation, vascularization and ulceration were developed by manipulating the alkali concentration.

Alkalies↗
PubMed1989

Factors influencing predilection and outcome in bacterial keratitis.

Complete records from 175 patients with 176 episodes of culture-proven bacterial keratitis treated over a 4-year period at the Massachusetts Eye and Ear Infirmary in Boston were analyzed. Sixty-three percent of the infections involved gram-positive organisms, and 40% involved gram-negative organisms; 15% were polymicrobial. There was a high incidence of infection with Staphylococcus aureus (28%), coagulase-negative staphylococci (14%), diphtheroids (14%), Pseudomonas aeruginosa (14%), and Streptococcus pneumoniae (12%). Gram stain correlation was achieved in 55%. Potential predisposing factors, usually multiple, were identified in 97% of the patients. Fifty percent of the ulcers were associated with such iatrogenic factors as prior topical corticosteroid therapy, penetrating keratoplasty, and contact lens use. Trauma occurred in only 16%. Several statistically significant associations of epidemiologic factors and outcome variables were revealed. Ninety-five percent of the ulcers resolved with therapy, but only 44% of the patients had visual acuity better than the level at admission, and 13% developed major complications.

Adolescent↗
PubMed1989

Causes and management of bacterial keratitis in the elderly.

The author evaluated 142 patients aged 65 years or older with microbial keratitis. There were relatively high rates of Pseudomonas aeruginosa infection unassociated with contact lens wear and of Streptococcus pneumoniae infection. The rates of quasicommensal and enteric infections were not proportionately elevated. Corneal disease, use of topical corticosteroids and use of contact lenses were the main predisposing factors. Patients with diabetes mellitus, dementia or chronic alcoholism appeared to be at higher risk. Trauma was rarely a factor. Complications requiring surgery were common. Corneal perforation developed in 20% of the patients, and endophthalmitis developed in 6%. The elderly often do not tolerate intensive topical antibiotic treatment well. Supplementary subconjunctival antibiotic injections under local anesthesia may be necessary. Corneal tissue glue, tarsorrhaphy and conjunctival flaps are probably underused in this age group.

Adrenal Cortex Hormones↗
PubMed1989

Standardized recording of acute corneal disease.

A simple form for standardized recording of acute corneal disease has been designed. It focuses on the discriminative features that are useful in the management of such disorders.

Corneal Diseases↗
PubMed1989

Dynamics of corneal epithelial healing after an alkali burn. A statistical analysis.

A precise definition of epithelial healing kinetics following chemical injury is necessary to aid the investigation of control mechanisms, potential therapeutic intervention and ophthalmic drug toxicity. Wound healing was studied photographically at frequent intervals in rabbits following 1N or 4N alkali burns. Planar wound areas were determined by computerized planimetry and transformed mathematically to curved surface data. The decrease in equivalent wound radius with time was computer-modelled using two linear and three nonlinear regressions. A periodic function was also investigated. Serial photographs showed that intermittent attrition of small areas of the migrating wound edge was a common confounding variable. Although excellent coefficients of determination were found for all models, the addition of nonlinear factors gave a small advantage. A mean lag phase of 3.96 and 6.52 hr occurred after 1N and 4N alkali burns, respectively; wound edge attrition was notably prevalent in early healing. Epithelial healing in the rabbit had a fundamental linear component, with mean epithelial migration rates of 76 and 80 microns/hr after 1N and 4N alkali burns, respectively, and which continued to closure. A quadratic nonlinear component was also suggested. No significant circadian component was detected.

Alkalies↗
PubMed1989

Gentamicin-resistant pseudomonal infection. Rationale for a redefinition of ophthalmic antimicrobial sensitivities.

Eight pseudomonal species were involved in 106 invasive infections of the eye; all were community acquired. Eighteen percent of the total and 9% of the Pseudomonas aeruginosa strains were gentamicin resistant, as defined using conventional criteria. All 10 cases of "resistant" pseudomonal (nine P. aeruginosa) keratitis responded satisfactorily to treatment with gentamicin. The resistance breakpoint (defined by safe serum levels in parenteral therapy) for most P. aeruginosa is much lower than ocular gentamicin levels achievable by optimal local application. We argue for a specific ophthalmologic definition of antibiotic resistance in infections of the cornea and external eye. MIC quantitative determinations of ocular isolates would provide more useful information to ophthalmologists than conventional qualitative disc sensitivity testing.

Adult↗
PubMed1989

Microbiology of contact lens-related keratitis.

We reviewed 397 cases of microbial keratitis examined at the Massachusetts Eye and Ear Infirmary, Boston, MA, U.S.A., from January 1982 through December 1985. Of these, 136 cases (34%) were related to contact lens use. Extended-wear contact lenses were used by 107 (79%) of these patients. Cosmetic contact lenses accounted for 59 (44%) of lens-related cases, aphakic contact lenses 44 (32%), and therapeutic (bandage) contact lenses 33 (24%). Fifty-three microbial keratitis cases associated with contact lens wear were culture-positive: 28 (52%) were gram-positive, and 19 (36%) were gram-negative. Mixed cultures, fungi, and Acanthamoeba accounted for two cases (4%) each. Pseudomonas aeruginosa was specifically associated with cosmetic soft contact lens use.

Adult↗
PubMed1988

Corneal infection in mucosal scarring disorders and Sjögren's syndrome.

We reviewed 69 episodes of microbial keratitis occurring over an 11-year period in 56 patients with a mucosal scarring disorder or Sjögren's syndrome. Gram-positive bacterial isolates were the most common cause of infection, and accounted for almost all cases in patients with Sjögren's syndrome. Trichiasis (cicatricial pemphigoid), topical corticosteroids, bandage contact lenses, and corneal surgery were the main predisposing factors in the development of the corneal infection. In patients with ocular cicatricial pemphigoid, infection was much less common after chemotherapeutic control had been achieved. Recurrent infections were relatively frequent. There was a high rate of major complications, particularly in microbial keratitis complicating Sjögren's syndrome.

Adolescent↗
PubMed1988

Microbial keratitis complicating penetrating keratoplasty.

A retrospective review of 68 consecutive episodes of microbial keratitis complicating 66 penetrating keratoplasties (PKs) showed major risk associations: suture-related problems (50%), contact lens wear (26%), previous herpes simplex infection (15%), graft failure (15%), and persistent epithelial defects (15%). Topical steroid (85%) and antibiotic (59%) usage were common iatrogenic factors. Half the infections occurred more than 1 year after grafting. Bacterial infections involving gram-positive organisms (59%) predominated, except for patients with extended-wear hydrophilic contact lenses, which usually involved gram-negative bacilli. The incidence of fungal infections (6%) was relatively low. Recommendations to minimize microbial keratitis include prompt attention to exposed, broken, or loose sutures, and preventive and therapeutic management of epithelial defects. The inadequacy of low-dose antibiotics in precluding microbial infection in many cases and the propensity to develop infections with resistant organisms suggest that guidelines for using postoperative and prophylactic topical antibiotics require reevaluation.

Corneal Transplantation↗
PubMed1988

Paraproteinemic crystalline keratopathy.

Paraproteinemic crystalline keratopathy is an uncommon complication of multiple myeloma and other plasma cell dyscrasias. A case of 16 years' duration was associated with an IgG kappa monoclonal gammopathy and recurrent uveitis. The corneal changes were unusually extensive and distributed throughout all corneal layers. The deposits consisted of diffuse, small, polymorphic aggregates, which were iridescent in the superficial cornea, mat elsewhere, and associated with a diffuse stromal haze; specular microscopy showed additional features. Both corneas were thickened. The deposits failed to stain histochemically, except patchily with Masson Trichrome. There was extensive immunohistochemical labeling for IgG, kappa, and surprisingly, lambda. Ultrastructurally, pleomorphic deposits were found in every corneal cell; paracrystalline deposits with internal banding were seen only in the basal epithelium. Keratocytes and endothelial cells were damaged and reduced in number. Disease recurred in a corneal graft. Three main types of paraproteinemic keratopathy can be distinguished. The deposits probably represent various metabolic products of the monoclonal protein. This is not necessarily a benign condition; hematologic control may be necessary on purely ophthalmological criteria.

Corneal Opacity↗
PubMed1988

Evidence for a feline reservoir for dysgonic fermenter 2 keratitis.

A 78-year-old female developed microbial keratitis from which corneal scrapings grew dysgonic fermenter 2. The infection initially responded poorly to a combination of topical antibiotics and corticosteroids but healed with intensive antibiotic therapy. There was no systemic predisposition to infection, and only feline exposure had occurred. Close association with a cat probably contaminated the eye.

Aged↗
PubMed1988

Chronic alcoholism and microbial keratitis.

In a series of 227 consecutive, non-referred patients with microbial keratitis an analysis of the accumulated hospital records showed that one-third were associated with chronic alcoholism. The diagnosis of alcoholism was usually unsuspected on admission to hospital. The microbial pathogenesis in these patients was distinctive; coagulase-negative staphylococci, alpha- and beta-streptococci, moraxellae, enteric Gram-negative bacilli, and polymicrobial infections were unusually prominent. Pseudomonas aeruginosa was uncommon. Trauma, exposure, bullous keratopathy, other external ocular diseases, and self-neglect were the major recognised predisposing causes. The nutritional, toxic and immunological sequelae of alcoholism may also have been contributory. Ophthalmologists should be alert to the diagnosis of chronic alcoholism in their patients. Chronic alcoholism may be an important and underrated risk factor for microbial keratitis.

Alcoholism↗