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Biomedical subjects

D J Coster

Publications and source records attributed to D J Coster.

At least 55 records · Page 3Linked to original sources
PubMed1996

Day ophthalmic surgery: aspects of perioperative care.

At Flinders Medical Centre in Adelaide, eye surgery under local anaesthesia (peribulbar block) has been carried out in the day ophthalmic surgery unit since 1987. In a subset of 536 patients, 112 patients required additional anaesthesia (supplementary retrobulbar block or regional muscle infiltration) to achieve full ocular paresis, and 10 patients required intraoperative supplementation of anaesthesia because of discomfort. Six patients had their surgery postponed (one had a retrobulbar haemorrhage and five became anxious after the procedure commenced). Sedation was rarely required and there were no adverse effects of the anaesthetic on surgical procedures or patients' vision. The authors conclude that peribulbar block provides satisfactory anaesthesia and that day ophthalmic surgery is safe and effective.

Adult↗
PubMed1996

Survival of rabbit limbal stem cell allografts.

Failure of a specialized population of corneal epithelial stem cells found in the peripheral cornea and limbus results in ocular surface disease, which may be amenable to treatment by transplantation of limbal tissue. This study was designed to investigate donor limbal stem cell allograft survival in rabbits with ocular surface disease. Rabbits underwent corneal epithelial debridement and limbal ablation to induce ocular surface disease and were then treated by limbal stem cell allotransplantation, by allotransplantation plus topical steroid, or by topical steroid only (n = 7 for each group). Donors and recipients were sex mismatched. Recipients were followed for up to 5 months. Outcome was assessed by daily slit-lamp examination, weekly impression cytology and photographic record, end-point sex chromatin and fluorescent cell tracer analyses, histology, and immunohistochemistry. In no case was a completely normal ocular surface regained, but some animals that received grafts plus corticosteroids fared best by all criteria used. In the absence of immunosuppression, graft hemorrhagia (believed to be a manifestation of graft rejection) occurred within the first month, the cornea became resurfaced with conjunctiva-derived cells, and no donor cells survived centrally in the long term. Topical corticosteroids reduced the number and severity of these episodes significantly, and were associated with survival of some donor-derived cells in the central cornea of some grafted animals. Thus, rabbit limbal stem cell allografts appeared to undergo rejection, which could be modified by immunosuppression, but useful regeneration of the ocular surface occurred only where rejection was circumvented.

Animals↗
PubMed1996

Cost effectiveness of cataract surgery. A comparison of conventional extracapsular surgery and phacoemulsification at Flinders Medical Centre.

PURPOSE: To compare the cost of conventional extracapsular cataract surgery and phacoemulsification at Flinders Medical Centre. METHODS: The costs of the two forms of cataract surgery were assessed over a 12-month period. During this period 410 cataract operations were performed. SETTING: The cataract surgery was carried out in a dedicated day surgery unit in a teaching hospital. OUTCOME MEASURE: The direct, indirect and tangible costs were measured. RESULTS: Conventional extracapsular cataract surgery with posterior chamber lens implant costs $1000.85 and phacoemulsification with lens implantation costs $1231.00. CONCLUSIONS: Although conventional extracapsular surgery generates slightly lower costs than phacoemulsification, the cost difference is small. In generating these figures, some assumptions must be made and the real difference may prove to be less than this.

Cataract Extraction↗
PubMed1996

Factors affecting bovine corneal endothelial cell density in vitro.

AIMS: To examine factors influencing the density and contact inhibition of bovine corneal endothelial cells cultured in vitro. METHODS: Cell counts were performed on bovine corneal endothelial cells cultured for various times in the presence of 10% fetal calf serum, with or without varying concentrations of growth factors, 5% dextran T-500, or 2% chondroitin sulphate, at 32 degrees C or 37 degrees C, and after treatment with beta galactosidase. RESULTS: Both basic fibroblast growth factor (FGFb) and retinal crude extract (RCE), but neither epidermal growth factor (EGF) nor acidic fibroblast growth factor (FGFa), increased endothelial cell density in vitro (p < 0.05). Continuous exposure to RCE resulted in a higher cell density than did a 24 hour pulse (p < 0.01), and higher cell densities were achieved at 37 degrees C than at 32 degrees C (p < 0.0001). In the absence of RCE, dextran T-500 increased cell density modestly (p < 0.05); in the presence of RCE, the addition of dextran T-500 had no effect on final cell density, whereas chondroitin sulphate significantly decreased final cell density (p < 0.01). In the absence of exogenous growth factors, beta galactosidase treatment resulted in a 50% increase in final cell density compared with controls (p < 0.0001). CONCLUSIONS: Bovine corneal endothelial cell growth can be augmented under conditions different from those used in corneal preservation systems. The final cell density in a confluent monolayer can be increased by treatment with beta galactosidase, suggesting that corneal endothelial cells may be contact inhibited through a beta galactosidase sensitive receptor system.

Animals↗
PubMed1995

Corneal virulence, cytopathic effect on human keratocytes and genetic characterization of Acanthamoeba.

Acanthamoeba keratitis is a sight-threatening complication of corneal trauma or contact lens wear. Although the majority of corneal isolates of Acanthamoeba belong to Group II in the Pussard-Pons classification based on cyst morphology, they have been placed in at least six species and their genetic relatedness is uncertain. The aim of this study was to determine the virulence of, and the relationship among, strains derived from the cornea, the nasal mucosa, and other environmental sources. To assess virulence, 10(4) trophozoites of each strain were incubated with monolayers of human corneal fibroblasts. By day 7, 12 of 29 strains tested had induced significant cytopathic changes. In addition, inocula of 10(4) cysts or trophozoites with 10(6) Corynebacterium xerosis were injected into the corneas of Porton rats; 11 amoebic strains induced infection within 7 days. The correlation between the virulence of trophozoites in vitro and in vivo was 86%. Using allozyme electrophoresis, 23 Acanthamoeba strains clustered into 5 major phylogenic divisions. Three divisions contained one or more strains that were virulent in the rat cornea. Virulent Pussard-Pons Group II strains clustered tightly to a fixed allelic difference of 13.6%. The eight corneal isolates clustered to 33%, dividing into three lineages. Five avirulent nasal isolates were strongly differentiated from other Group II strains. The results were not in accord with species designations based primarily on morphological criteria. These data suggest that particular subsets of Acanthamoeba strains are virulent in the human cornea.

Acanthamoeba↗
PubMed1995

Use of DNA polymorphisms and the polymerase chain reaction to examine the survival of a human limbal stem cell allograft.

PURPOSE: The extent to which limbal epithelial stem cell allografts will repopulate the human corneal ocular surface, and the time frame over which such cells survive, are uncertain. We investigated the survival of donor-derived epithelial cells after limbal stem cell allotransplantation in a patient with bilateral limbal stem cell failure by using short tandem-repeat DNA polymorphisms to distinguish donor and recipient cells. METHODS: Epithelial cells were harvested by impression cytology from the grafted eye before and at various times after transplantation. DNA was extracted and amplified by the polymerase chain reaction at an informative locus, D8S264. RESULTS: Cells of donor genotype were present over the grafted areas at the time of surgery but were not detected in the central cornea until 12 weeks postoperatively, indicating that repopulation of the epithelial surface from transplanted limbal stem cells took considerable time. However, by the 20th postoperative week, only recipient-type cells were detected in the grafted eye, despite systemic immunosuppression of the recipient with azathioprine and cyclosporine. CONCLUSIONS: Discrimination between donor and recipient cells on the ocular surface after limbal allotransplantation was possible using genotypic variation at DNA polymorphic sites (microsatellites). Long-term survival of donor cells after limbal transplantation did not occur in this patient. Detection of DNA polymorphisms amplified by the polymerase chain reaction is a simple, rapid, and noninvasive method of following the course of transplanted cells at the ocular surface.

Adult↗
PubMed1995

How successful is corneal transplantation? A report from the Australian Corneal Graft Register.

Corneal graft outcome was assessed within a large, prospectively collected database of 4499 records. Penetrating corneal graft survival was 91% at 1 year, 72% at 5 years and 69% at 7 years. The three most common indications for graft were keratoconus (30%), bullous keratopathy (25%) and failed previous graft (18%); the three most common causes of graft failure were rejection (34%), infection (18%) and glaucoma (9%). The vast majority of grafts were performed for improved visual acuity. About four-fifths of recipients achieved at least one line of better acuity on the Snellen chart post-operatively; of the remainder with unchanged or worse acuity, only 21% had failed grafts. Overall, 43% of recipients achieved a best corrected Snellen acuity of 6/12 or better, 52% achieved 6/18 or better, and 20% had acuitities of less than 6/60. Reasons for poor post-operative acuity (recorded as less than 6/60) included graft failure (41%) and comorbidities in the grafted eye (43%). A number of risk factors for graft failure were examined: in most instances, there was little room for decision-making or expert intervention.

Astigmatism↗
PubMed1995

Surgical management of ocular surface disorders using conjunctival and stem cell allografts.

AIMS: The aim of this work was to investigate different surgical options for the repair of the ocular surface, using various extensions of the procedure of limbal stem cell allotransplantation. METHODS/RESULTS: Straightforward lamellar limbal transplantation was performed in one patient with contact lens induced limbal stem cell failure. A second patient with a neoplastic corneal lesion underwent limbal allotransplantation, followed later by a second procedure in which 360 degrees of limbus and the entire ocular surface was transplanted. A third patient who had suffered extensive chemical burns was treated by penetrating keratoplasty to restore central corneal clarity, followed later by a lamellar allograft comprising a 360 degrees annulus of peripheral cornea to repair the ocular surface. A fourth patient with long standing, chronic trachomatous eye disease underwent allotransplantation of the upper lid tarsal plate and conjunctiva, with reconstruction of the fornix. Finally, a child with Goldenhar's syndrome underwent reconstruction of the medial fornix with autologous buccal mucosa, followed by a lamellar corneal and conjunctival allograft. A stable ocular surface has been achieved in each case and there have been no obvious rejection episodes. CONCLUSION: Limbal allotransplantation can be extended to engraftment of the entire superficial cornea, limbus, conjunctiva, and tarsal plate in patients with a range of pathologies. We have described the surgical management of five cases which demonstrate the potential of the technique, but which raise questions which still need to be explored.

Adult↗
PubMed1994

Doyne Lecture. Influences on the development of corneal transplantation.

The current status of corneal transplantation is determined by historical events and current research findings. Many of the important historical events occurred in and around Oxford: the beginning of visual science, corneal transplantation and transplantation in immunology. Contemporary research yields data from a number of different sources: clinical trials, registries, surveys, animal experiments and in vitro studies. This information has been used by clinicians to bring about a steady improvement in the outcome of corneal transplantation.

Animals↗
PubMed1994

The Australian Corneal Graft Registry (ACGR).

The value of a register of corneal grafts is that it can provide new data about the long-term outcome of corneal transplantation and may allow a more reasoned distribution of scarce donor corneas. The large numbers of cases and events can accommodate wide variations in practice patterns without losing statistical power. The Australian Corneal Graft Register follows over 6000 cases; univariate and multivariate analyses are performed every two years. Amongst the interesting recent findings of the analyses are that a past history of elevated intraocular pressure and early graft suture removal are associated with graft failure, as are the more well-established factors of inflammation, neovascularization, formation of synechiae and recurrence of herpetic eye disease. Donor corneas harvested from relatively elderly donors, however, do not appear to be associated with graft failure. Best-corrected visual acuity achieved post-operatively is very variable, but depends to some extent on the original indication for graft.

Adult↗
PubMed1994

Arthrogryposis multiplex congenita: a report of two cases.

Arthrogryposis multiplex congenita refers to a group of birth defects characterised by multiple joint contractures. The syndrome is caused by neuropathic disease, myopathic disease, or any other cause of decreased fetal joint mobility. Multiple and usually symmetric joint abnormalities with associated muscular and soft tissue hypoplasia are noted at birth. A variety of associated congenital anomalies affecting many organ systems are frequently found. Ocular and orbital findings have been described in patients with arthrogryposis but corneal disease has only rarely been reported. We present corneal findings in two patients with arthrogryposis and discuss the implications for disease pathogenesis. Previous ophthalmologic reports are also reviewed.

Adolescent↗
PubMed1994

Acanthamoeba keratitis. Resolution after epithelial debridement.

Two patients presented with dendritiform epithelial irregularities of the cornea that were unresponsive to topical acyclovir. Both were soft contact lens wearers who had practiced inadequate lens hygiene. Acanthamoeba was cultured from a shallow corneal biopsy of one patient and from the contact lens of the other. Epithelial debridement resolved the condition in both patients without concomitant treatment with antiamoebic agents.

Acanthamoeba↗
PubMed1993

Storage, surgery, outcome, and complications of corneal and conjunctival grafts.

Corneal transplantation is still limited by a shortage of donor material, but the type of storage medium used once a cornea has been acquired is probably irrelevant to graft outcome. Vancomycin HCl shows promise as a supplement to gentamicin sulfate in storage media. New methods of HLA typing using donor ocular tissue have largely helped to overcome the problems associated with typing of cadaveric blood, but the value of HLA typing in improving corneal graft survival is now in doubt. Alternative regimens of immunosuppression are being tested in animal models, but there is still no consensus on the best ways to use existing agents such as corticosteroids. Rejection remains the most common cause of unsuccessful corneal grafting in large cohorts, but glaucoma and astigmatism also limit postoperative graft function. Limbal stem cell grafts are promising for the management of many ocular surface diseases and conjunctival limbal autografts for pterygia may be the most successful surgical method for preventing recurrence.

Anti-Bacterial Agents↗