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R Casson

Publications and source records attributed to R Casson.

13 recordsLinked to original sources
PubMed2006

Comparison of the ICare rebound tonometer with the Goldmann applanation tonometer by experienced and inexperienced tonometrists.

PURPOSE: To assess the agreement between ICare rebound tonometer and Goldmann applanation tonometer in the hands of experienced and inexperienced tonometrists. PATIENTS AND METHODS: Two tonometrists, experienced with both Goldmann applanation tonometry (GAT) and ICare Tonometry (ICT) measured intraocular pressure (IOP), in a masked fashion, in 100 patients. In another series of 58 patients, ICT was performed by an inexperienced tonometrist and GAT by an experienced tonometrist. RESULTS: In approximately 80% of patients, the difference in IOP between GAT and ICT was <or=2 mmHg in group 1 and <or=3 mmHg in group 2. The 95% limits of agreement were -4.0-4.4 mmHg in group 1 and -6.0-5.0 mmHg in group 2. CONCLUSION: ICT compares reasonably with GAT, in both experienced and inexperienced hands. Its ease of use, portability, and sterility make it an attractive tonometer. Its degree of accuracy in inexperienced hands would make it a useful instrument for health care workers with limited ophthalmic experience.

Aged↗
PubMed2006

South Australian adolescent ophthalmic sun protective behaviours.

AIMS: To study student's knowledge of the effects of sunlight on the eyes, as well as their sun protective behaviours. METHODS: In total, 640 [corrected] students aged 13-18 years were surveyed in South Australia, during August-September 2004, using a standardized previously used survey. Scores were calculated regarding knowledge about ultraviolet light, sunlight effects on eyes, as well as eye and body protection. Risk factor scores were produced for each student. The data were analysed by the analysis of variance (ANOVA), as well as the Cochran-Mantel-Haenszel methods. Results were compared to the same survey conducted in 1995 in Queensland Australia. RESULTS: This group demonstrated a moderate level of knowledge, similar to the 1995 survey. Students in the older age groups demonstrated significantly higher knowledge. The majority of students (74%) owned a pair of sunglasses; however, 44.5% almost never wore their glasses. The reported frequency of wearing sunglasses was significantly related to advertising, believing sunglasses protect the eyes, as well as personal, family, and peer attitudes towards wearing sunglasses. CONCLUSION: The results of our survey suggest no significant change in knowledge and behaviours of students, compared to the 1995 survey. We feel it is imperative that adolescents be made more aware of the damaging effects of sunlight and the benefits of eye protection. Health promotion campaigns should target the youth and consider that as a group, they are significantly influenced by the media, peers, and family attitudes.

Adolescent↗
PubMed2004

Effectiveness of levobetaxolol and timolol at blunting retinal ischaemia is related to their calcium and sodium blocking activities: relevance to glaucoma.

Glaucoma is a chronic optic neuropathy in which retinal ganglion cells die over a number of years. The initiation of the disease and its progression may involve an ischaemic-like insult to the ganglion cell axons caused by an alteration in the quality of blood flow. Thus, to effectively treat glaucoma it may be necessary to counteract the ischaemic-like insult to the region of the optic nerve head. Studies on the isolated optic nerve suggest that substances that reduce the influx of sodium would be particularly effective neuroprotectants. Significantly, of the presently used antiglaucoma substances, only beta-blockers can reduce sodium influx into cells. Moreover, they also reduce the influx of calcium and this would be expected to benefit the survival of insulted neurones. Betaxolol is the most effective antiglaucoma drug at reducing sodium/calcium influx. Our electroretinographic data indicated that topical application of levobetaxolol to rats attenuated the effects of ischaemia/reperfusion injury. Timolol was also effective but to a lesser extent. Based on these data we conclude that beta-blockers may be able to blunt ganglion cell death in glaucoma, and that levobetaxolol may be a more effective neuroprotectant than timolol because of its greater capacity to block sodium and calcium influx.

Animals↗
PubMed2004

Normal tension glaucoma is not associated with the common apolipoprotein E gene polymorphisms.

BACKGROUND: /aims: In normal tension glaucoma (NTG) factors other than raised intraocular pressure have a role in the pathogenesis of the optic neuropathy. Because particular apolipoprotein E (ApoE) gene polymorphisms have been associated with cell death and survival in neurological degenerative diseases, the purpose of this study was to determine the ApoE allele frequencies in patients with normal tension glaucoma. METHODS: The apolipoprotein E genotype of 155 patients with normal tension glaucoma was compared to that of 349 non-affected, control subjects from the same geographical area. A similar comparison was made between 53 patients with normal tension glaucoma who demonstrated progressive visual field loss, and control subjects. The frequencies of genotypes was compared with the chi(2) test and Mantel-Haenszel coefficent. RESULTS: There was no significant difference in the frequency of ApoE alleles or genotypes in the normal tension glaucoma population compared to the control group. The ApoE alleles and genotypes in NTG patients with progressive disease were not different from the control group. CONCLUSION: ApoE gene polymorphisms are not linked to normal tension glaucoma, suggesting that this gene does not have a role in the pathogenesis of optic neuropathy in this disease.

Adult↗
PubMed2003

Some current ideas on the pathogenesis and the role of neuroprotection in glaucomatous optic neuropathy.

The primary features of glaucomatous optic neuropathy are characteristic changes in the optic nerve head, a decrease in number of surviving ganglion cells and a reduction in vision. It is now generally accepted that a number of factors, including elevated intraocular pressure, could lead to the changes seen in the optic nerve head and to obtain a pharmacological means to treat the causes will vary from patient to patient. In contrast, a cascade of events have been proposed to explain how the changes in the optic nerve head may lead to the slow and differential death of ganglion cells in the disease. It is also proposed that drugs (neuroprotectants) influencing this cascade of events can attenuate ganglion cell death and lead to the treatment of all glaucoma patients.

Animals↗
PubMed2002

Phacoemulsification with intraocular lens implantation after trabeculectomy.

PURPOSE: To determine the effect of phacoemulsification with intraocular lens (IOL) implantation, using a superior clear-corneal incision, on the long-term intraocular pressure (IOP) control in patients who have undergone previous trabeculectomy. METHODS: Twenty-eight consecutive patients who underwent phacoemulsification with IOL implantation (phaco group) at least 3 months after trabeculectomy were identified and matched to 28 patients who underwent trabeculectomy only (trabeculectomy-only group) with respect to age, gender, IOP, and duration of follow-up. The mean IOP was compared 1 and 2 years after phacoemulsification, and the surgical success rate in each group was determined by Kaplan-Meier survival analysis. RESULTS: The mean IOP 1 year after cataract surgery was significantly higher ( = 0.025) in the phaco group (15.6 +/- 3.5 mm Hg) than in the trabeculectomy-only group (13.4 +/- 2.5 mm Hg), but at 2 years the difference was not statistically significant (15.3 +/- 3.1 mm Hg in the phaco group compared with 14.3 +/- 3.2 mm Hg in the trabeculectomy-only group; = 0.35). Two years after surgery, 5 of 28 patients in the phaco group and 1 of 28 patients in the trabeculectomy-only group had commenced or were using additional topical medication ( = 0.089). If the introduction of glaucoma medication was considered a "failure," then the IOP control was significantly better in the trabeculectomy-only group using two different criteria for surgical failure. CONCLUSION: Although phacoemulsification and IOL implantation through a superior clear-corneal incision have little effect on mean IOP in a group of patients who have undergone previous trabeculectomy, this procedure may jeopardize the long-term IOP control in individual patients.

Aged↗
PubMed2001

Clinical comparison of frequency doubling technology perimetry and Humphrey perimetry.

AIM: To determine the number of missed points on frequency doubling technology (FDT) perimetry that optimise the sensitivity and specificity of the test and to determine the topographical accuracy of the test in a clinical setting. METHODS: In a prospective study, the perimetric data from 99 patients who underwent both FDT perimetry in the screening mode and Humphrey 24-2 (H24-2) were used to determine the sensitivity and specificity of the FDT perimetry compared with the full threshold H24-2 as the gold standard. RESULTS: Missed points on the FDT perimetry correlated with both the mean deviation and the corrected pattern standard deviation on the Humphrey perimetry. A score assigned to abnormal points on the FDT perimetry and the Humphrey total deviation plot showed a significant correlation for both the location and the depth of the defect. In comparing the Humphrey hemifield test with the FDT perimetry results, if at least one missed point on the frequency doubling test was considered as abnormal then the overall sensitivity of the test was 78.1% and the specificity was 89.1%. CONCLUSION: FDT perimetry in the screening mode performed in a clinical setting was highly specific, exhibited reasonable sensitivity, and accurately determined the location and depth of scotomas when compared with the full threshold Humphrey 24-2.

Aged↗
PubMed2001

Long term results and complications of trabeculectomy augmented with low dose mitomycin C in patients at risk for filtration failure.

AIM: To determine the results and complications up to 5 years after trabeculectomy with 0.02% mitomycin C (MMC) in glaucoma patients at risk for failure of filtration surgery. METHODS: A consecutive series of 21 eyes from 20 patients who underwent trabeculectomy with MMC 0.02%, with an exposure time of 2 minutes, was retrospectively analysed and the results were compared with previously published data. RESULTS: The mean preoperative intraocular pressure (IOP) was 28 mm Hg on an average of 2.8 glaucoma medications, and the mean postoperative IOP after 3 years was 14 mm Hg on an average of 0.4 medications. Three years after trabeculectomy, 17 of 21 (80.9%) eyes had an IOP of less than 21 mm Hg without medical treatment. Using Kaplan-Meier life table analysis the 5 year probability of an IOP less than 21 mm Hg without medication was 67% and with medication was 90%. Two patients required further glaucoma surgery during the first postoperative year, and another developed hypotonous maculopathy which was reversed after bleb revision. Seven patients developed visually significant cataract as a late consequence of the surgery. There were no bleb related infections. CONCLUSION: In the long term MMC 0.02% used for 2 minutes intraoperatively is an effective adjunctive treatment in glaucoma patients at risk for bleb failure and in this dose is associated with few complications.

Aged↗
PubMed2000

Evaluation of environmental levels and biological impact of TBT in Malta (central Mediterranean).

Chemical monitoring for butyltins in bulk seawater, surface microlayer and superficial sediments determined that the two main local sources of marine contamination by tributyltin (TBT) compounds in Malta are ship-repairing dockyards and marinas. In bulk seawater, TBT values ranged from below the detection limit of 5 ng Sn l(-1) to 300 ng Sn l(-1); in sediments derived from the most polluted areas, TBT concentrations as high as 1500 ng Sn g(-1) were measured. At TBT levels found in local harbours, several sublethal biological responses are possible and were observed, including a significant reduction in MFO enzyme system activities of fish; digestive cell atrophy in the oyster Ostrea edulis; and induction of imposex in the snail Hexaplex trunculus. The latter two responses are evident at TBT concentrations below the environmental quality standard (20 ng TBT l(-1)). The ecological implications of these results are discussed and it is concluded that exposure of marine organisms to TBT in local harbours may be expected to lead to a reduction in the long-term survival of a number of such organisms. For these reasons, both the use of TBT-based antifouling paints for pleasure boats as well as drydock practices need to be controlled by appropriate regulations and their enforcement.

Animals↗
PubMed1996

Prevalence of blindness and visual impairment in an elderly urban population.

BACKGROUND: Accurate data on the prevalence of blindness in urban populations is not readily available. The Australian Longitudinal Study of Ageing is a prospective multidimensional study examining a broad range of age-related health issues, including visual function. METHODS: A population-based sample of 1466 persons, 70 years of age and over, from the Adelaide metropolitan area underwent visual acuity measurement. RESULTS: Approximately 1% were legally blind by Australian definitions. CONCLUSIONS: This percentage is low by world standards, however projections indicate that the absolute number of blind elderly people is rapidly increasing. Data such as this are crucial for the planning of adequate ophthalmic care.

Age Distribution↗