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Biomedical subjects

D L Easty

Publications and source records attributed to D L Easty.

At least 19 recordsLinked to original sources

Suitability for day case cataract surgery.

Areas of concern about day case surgery are highlighted. A group of 442 patients underwent cataract surgery with lens implant. They were randomly allocated to day case or inpatient groups. Questionnaires were used to assess opinions about day case cataract surgery and how patients felt they would manage. None of the areas of concern were actually a problem. Difficulties encountered by patients and clinicians in the postoperative period are discussed. Most patients appear suitable for day case surgery provided they are well informed.

Activities of Daily Living

A comparison of 141 polymacon (Iogel) and 140 poly(methyl methacrylate) intraocular lens implants.

In a prospective controlled trial 290 consecutive patients were randomly allocated a polymacon or a poly(methyl methacrylate) (PMMA) intraocular lens. Early Treatment of Diabetic Retinopathy Study (ETDRS) acuity charts gave similar results with both lenses. However Pelli-Robson contrast sensitivity charts gave a better result with PMMA lenses. Polymacon lenses appeared to remain free of any adhesions after implantation raising the question of long term stability. Four patients experienced problems related to this, three involved total lens dislocation. Seven patients developed early 'fibrin' membranes coating the polymacon lens, of which three were florid.

Aged

Non-traumatic acquisition of herpes simplex virus infection through the eye.

Primary ocular herpes is usually seen as a follicular conjunctivitis and blepharitis, with or without involvement of the cornea. It is unknown, however, to what extent asymptomatic and/or subclinical primary disease occurs, and whether primary ocular herpes follows direct droplet spread to the eye. Previous models of murine ocular herpes have used trauma (scarification) to introduce virus into the cornea, producing disease which results in significant corneal scarring. To mimic a likely route of infection in humans, a droplet containing virus was placed on the mouse eye and clinical disease recorded. At least 1 month after inoculation, serum was assayed for neutralising antibodies and the cornea, iris, and trigeminal ganglion were investigated for evidence of herpes simplex virus type 1, by cocultivation and the polymerase chain reaction. Some animals showed a severe ulcerative blepharitis with little to no involvement of the cornea, while disease was undetectable in others. The development of disease depended on the dose and strain of virus and age of the animal, with older mice appearing more resistant. Virus was isolated from the trigeminal ganglion of younger animals inoculated with higher doses of virus, after 21 days in culture, suggesting that latency had been established. Neutralising antibodies were present in most mice irrespective of the presence of recognisable clinical disease. Using primers for the thymidine kinase and glycoprotein C regions of the viral genome, herpes simplex virus type 1 DNA was found in the cornea, iris, and trigeminal ganglion of most animals and showed a good correlation with the presence of neutralising antibodies. It would thus appear that herpes simplex virus type 1 is able to accede into the cornea, iris, and trigeminal ganglion following nontraumatic application of virus onto the mouse eye. This model mimics primary ocular disease in humans and may be useful for studies on recurrent disease and the spread of ocular herpes.

Animals

Long-term survival of endothelium following transplantation of corneas stored by organ culture.

This study reports corneal graft survival, endothelial cell changes, and visual outcome in 20 patients who received some of the first corneas stored by organ culture in the Corneal Transplant Service Eye Bank in Bristol. Mean donor age was 48 years (SD 15, n = 20) and corneas were stored for an average of 21 days (SD 7, n = 20). Preoperative endothelial cell density was 2334 cells/mm2 (SD 235, n = 18) and this fell by 8% (SD 12) to 2158 cells/mm2 (SD 372) within the first 2 months following transplantation. In 13 patients, endothelial cell density thereafter declined exponentially with a half-life of 41 months (SD 17, n = 12; one patient excluded as an outlier). Corneas that suffered rejection episodes showed the highest rates of loss of endothelial cells. Endothelial cell loss 4 years after transplantation was 46% (SD 16, n = 12), which was similar to the postoperative decline in cell density reported for corneas stored for far shorter periods in McCarey-Kaufman medium at 4 degrees C.

Adult

Immunological aspects of corneal graft rejection.

Immunological graft rejection is a major cause of corneal graft failure. HLA class I and II antigens are expressed by various cells within the cornea and during sensitisation of the recipient donor antigens appear to be presented by both donor and recipient antigen presenting cells. Certain donor and host factors have been shown to influence the incidence of corneal graft rejection, and the manipulation of these factors is discussed.

Corneal Transplantation

Patient perceptions and social impact. Preliminary results of the Bristol MRC Study.

One hundred and nine inpatients were compared with 84 day cases by means of specially designed questionnaires presented at set times by staff other than the operating surgeon. The aim was to highlight patient attitudes, expectations and satisfaction with a standard method of endocapsular cataract extraction and posterior chamber lens implant under local anaesthetic as either a day case (DC) or an inpatient (IP). The results showed a high patient acceptance of whichever method of management was chosen. Both groups appeared satisfied with their treatment and the final result. The cost of DC and IP treatment was assessed.

Ambulatory Surgical Procedures

In vitro corneal pathogenicity of Acanthamoeba.

The comparative cytopathic effects of a keratitis and an environmental isolate of Acanthamoeba were studied on confluent monolayers of human and rabbit corneal cells grown in culture. The presence of cells in culture induced excystment of amoebae to the active trophozoite form. Total destruction of cell monolayers was observed to be similar for both isolates, and dependent on incubation time and amoebic concentration. The relevance of these findings to human and experimental Acanthamoeba keratitis is discussed.

Acanthamoeba

Tranexamic acid-associated ligneous conjunctivitis with gingival and peritoneal lesions.

A considerable number of agents have been proposed as causing ligneous conjunctivitis. We report the first case to arise as a side effect of tranexamic acid (Cyclokapron), an anti-fibrinolytic drug used in the treatment of menorrhagia. In addition to the typical conjunctival changes our patient had lesions affecting the gingiva and the peritoneum the last causing considerable protein loss into the peritoneal cavity.

Adult

Experimental Acanthamoeba keratitis: II. Immunohistochemical evaluation.

In a Wistar rat experimental model of Acanthamoeba keratitis immunohistochemical techniques were used to analyse the host cellular response. The inflammatory cell profile was observed to change at intervals. In tissue sections the cellular response consisted of neutrophils on the first day but predominantly macrophages on the following days. Some T lymphocytes but no B lymphocytes were observed.

Acanthamoeba

Effect of mismatches for major histocompatibility complex and minor antigens on corneal graft rejection.

The importance of minor histocompatibility genes in corneal graft rejection was investigated using a model that simulates the major histocompatibility complex (MHC) and minor mismatches of the human allograft more accurately than previous animal models. DA(RT1a) x LEW(RT1(1]F1 hybrid rats were backcrossed to LEW, and the backcross generation were used as corneal graft recipients. Female DA(RT1a) strain animals were used as donors throughout. As in humans, the MHC disparity (a to 1) between each donor-recipient pair could be controlled; minor mismatches were variable and unknown. The MHC haplotype of each backcross individual (either homozygous l/l) or heterozygous a/l) was determined. Depending on this haplotype, the transplanted DA cornea was either matched or mismatched with the recipient for MHC antigens. The average proportion of minor disparate loci was 50%, although this was variable and unknown from recipient to recipient. Some animals of each MHC type were sensitized with three subcutaneous DA strain skin grafts at intervals of 2 weeks. Prior sensitization caused more rapid corneal graft rejection in both MHC mismatched (P less than 0.001) and matched (P less than 0.01) animals. All animals in the two MHC-mismatched groups (sensitized, 26; unsensitized, 17) and most in the MHC-matched groups (sensitized, 25 of 27; unsensitized, all 13) rejected their grafts. The MHC matching resulted in a greater range of survival times, although the difference in survival in unsensitized animals between matched and mismatched groups was not significant (unsensitized, P greater than 0.05; sensitized, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals

External eye flora as a nutrient source for Acanthamoeba.

Certain bacteria cause excystment of Acanthamoeba from cyst to trophozoite form and are then ingested by migrating trophozoites. We studied the response of Acanthamoeba cysts to inoculation on agar seeded with three types of commensal eye bacteria and Escherichia coli. Amoebae excysted on all bacteria tested, and the migration rate of Acanthamoeba trophozoites on each was compared. Acanthamoeba migrated with equal speed on E. coli and Staphylococcus epidermidis. Migration was observed, but was more slow on Micrococcus and Corynebacterium. Commensal bacteria on the eyelids, conjunctiva and tear film may have a role in pathogenesis of Acanthamoeba keratitis.

Acanthamoeba

Possible latent infection with herpes simplex virus in the mouse eye.

Herpes simplex virus (HSV) was isolated from organ cultures of anterior segments of the eyes of mice inoculated with virus on the snout or directly onto the cornea at least 5 weeks previously. The frequency of isolation of the virus was not decreased by treatment of the animals with acyclovir, suggesting that the virus is latent by the criteria usually applied. Peroxidase-antiperoxidase staining of organ cultures that had shed virus showed that viral antigens were predominantly present in the anterior uvea. Inoculation of mouse eye anterior segments in vitro showed that this tissue was the most susceptible to productive infection. These results suggest the possibility that HSV can establish a latent infection in tissues of the anterior segment of the mouse eye.

Acyclovir