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Biomedical subjects

Lawrence W Hirst

Publications and source records attributed to Lawrence W Hirst.

6 recordsLinked to original sources
PubMed2006

Iris melanoma in 12-year-old boy.

A 12-year-old boy presented with an incidental finding of an iris lesion after blunt injury. Ocular examination revealed a large atypical brown vascular nodule in the nasal iris, extending to the pupillary margin. There were smaller scattered nodules scattered within the iris and anterior chamber. Ultrasound biomicroscopy examination revealed no tumour behind the iris. Fundal examination findings were normal. Sector iridectomy revealed mixed spindle and epitheliod melanoma. The eye was enucleated. Histopathologic examination confirmed malignant melanoma confined to the iridocorneal angle, iris, ciliary body and inner layer of the anterior sclera. Iris melanomas are very rare in the prepubertal age group.

Child↗
PubMed2004

Controlled trial of hyperbaric oxygen treatment for alkali corneal burn in the rabbit.

PURPOSE: To evaluate the efficacy of hyperbaric oxygen therapy in the treatment of alkali-induced corneal burns in an animal model. METHODS: Twenty-four rabbits were randomized into a control group (n = 12) and hyperbaric oxygen treatment group (n = 12). After induction of anaesthesia, the alkali burn model was established by application of 1 N sodium hydroxide to one eye of each rabbit. The hyperbaric oxygen treatment group was treated each day for 21 days with hyperbaric oxygen at 2.4 Atmospheres Absolute (ATA) for 1 h. The eyes of the animals were examined daily for 2 weeks and then weekly until the end of the trial. The principal endpoint was that of perforation of the cornea at which time the animals were killed with a lethal dose of either intravenous or intraperitoneal barbiturate and the eyes immediately enucleated and fixed in 10% neutral buffered formalin. All animals in which complete healing took placed were also killed, the eyes removed, fixed and examined histologically. Photographs were taken of the rabbit's eyes at weekly intervals and the area of vascularization and epithelial defects in the hyperbaric and control groups were compared. RESULTS: Equal numbers (seven) of the control and hyperbaric oxygen treated groups had perforated corneas and there was no statistical difference in the mean time to perforation (control 30.1 days; treated 30 days). There was also no statistical difference between the two groups with respect to epithelial defect size. CONCLUSION: Treatment with hyperbaric oxygen for 1 h daily for 21 days had no beneficial effect on alkali-induced corneal burns.

Animals↗
PubMed2003

Sun exposure as a risk factor for nuclear cataract.

BACKGROUND: Cataracts are the leading cause of blindness and visual impairment throughout the world. An association of sun exposure with cortical cataract has been well established, but the association with nuclear cataract remains unclear. METHODS: This case-control study was nested within the Nambour (Australia) Trial of Skin Cancer Prevention conducted between 1992 and 1996. We compared 195 cases who had a nuclear opacity of grade 2.0 or greater with 159 controls. Structured questionnaires were used to ascertain lifetime sun exposure history, eyeglasses and sunglasses use, and potentially confounding variables such as education and smoking. RESULTS: There was a strong positive association of occupational sun exposure between the ages of 20 and 29 years with nuclear cataract (odds ratio = 5.9; 95% confidence interval = 2.1-17.1). Exposure later in life resulted in weaker associations. Wearing sunglasses, particularly during these early years, afforded some protective effect. CONCLUSIONS: This study provides new evidence to support a link between sun exposure and nuclear cataract. Risk was highest among those with high sun exposure at younger ages.

Adolescent↗
PubMedDate not supplied

The treatment of pterygium.

The treatment of pterygium is still quite controversial, with various treatments being advocated in the scientific literature. Unfortunately, there are very few well-conducted controlled clinical trials of treatments. However, years of anecdotal and noncontrolled studies have confirmed that some methods, such as bare scleral closure, are no longer acceptable in the treatment of pterygium and that other methods are likely to be more useful. In the future it will be important to develop a grading system, and surgeons will need to be conservative in the treatment of pterygium until such time as a single treatment provides a lower recurrence rate and complication rate.

Antineoplastic Agents↗