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Biomedical subjects

C J Barry

Publications and source records attributed to C J Barry.

33 records · Page 2Linked to original sources
PubMed1998

Expression of cell adhesion molecules and vascular endothelial growth factor in experimental choroidal neovascularisation in the rat.

AIMS: To investigate the longevity and reproducibility of choroidal neovascularisation (CNV) induced by krypton laser photocoagulation in the rat. The presence of cell adhesion molecules (CAMs) and vascular endothelial growth factor (VEGF) during the development of CNV was also studied. METHODS: 67 pigmented rats underwent retinal photocoagulation by krypton laser. The eyes were examined by either single or serial fluorescein angiography at 3 days, 1, 2-3, 4-5, 7-8, and 12 weeks post photocoagulation. The expression of CAMs (ICAM-1, E-selectin, and CD44) and VEGF post photocoagulation was studied by immunohistochemistry. RESULTS: CNV related fluorescein leakage appeared in 46.4% of 766 laser spots delivered to the 58 eyes that were tested at 2-3 weeks post treatment. The ratio of hyperfluorescent laser sites did not change significantly at 8 weeks post laser. The number of leaky spots was independent of the total number of lesions delivered to each eye (at 2-3 weeks post laser 10-15 spots/eye: 44% and 25-30 spots/eye: 49%; t = 0.7673; p = 0.3903). Nine eyes were followed by serial angiography between 2 and 12 weeks. The laser spots with fluorescein leakage at 2 weeks (51.5%) remained leaky at 12 weeks (51.5%). Histopathologically, macrophage accumulation peaked at 5 days and CNV was firstly observed at 1 week post photocoagulation. ICAM-1, E-selectin, CD44, and VEGF were maximally induced at 3-5 days post laser photocoagulation, and were localised to RPE, choroidal vascular endothelial, and inflammatory cells. VEGF was also detected in intravascular leucocytes at the sites of laser lesions. CONCLUSIONS: These studies demonstrated that krypton laser photocoagulation can be successfully used to produce lesions similar to those of human CNV. The response induced remained present for an extended period of time (12 weeks), thus offering a potential model to screen candidate CNV inhibitory agents. In addition, it is proposed that the expression of ICAM-1, E-selectin, CD44, and VEGF before new vessel formation might be linked to the initiation of CNV.

Animals↗
PubMed1997

Optic disc haemorrhages and vascular abnormalities in a glaucoma population.

PURPOSE: To retrospectively examine the optic disc photographs of a glaucoma population for optic disc haemorrhages, vascular occlusions and vascular abnormalities. METHODS: The optic disc photographs of 906 eyes of glaucoma and suspect glaucoma patients were examined. Optic disc photographs were taken annually, where possible, with the follow-up period varying between 1 and 14 years duration (mean, 2.89). Glaucoma patients are regularly reviewed every 4-6 months and glaucoma suspects every 1-2 years, depending on the ophthalmologist. Low-tension glaucoma patients were reviewed more frequently (mean, every 2.6 months). The results of the findings were compared to a control group of 39 subjects with a mean follow-up period of 7 years, using Fisher's exact test. RESULTS: It was found that during the period under review, 7.4% (n = 67) of eyes had optic disc haemorrhages. The highest frequency of optic disc haemorrhages (37.5%) was found in the low tension glaucoma group (P = 0.0001) followed by 11% of primary open-angle glaucoma eyes (P = 0.03). In the normal group there were three eyes with optic disc haemorrhages and one with a disc collateral, which constitutes 5.1% vascular changes in this sub-group. Of the study eyes 2.8% had central retinal vein occlusions, 1.3% branch vein occlusion, 1.2% disc vessel abnormalities (loops) and 1.1% disc collaterals. Discrete nerve fibre layer haemorrhages and microaneurysms were found in 0.8% and 1.8% of eyes, respectively. CONCLUSIONS: A total of 16.8% of the eyes observed in this study had either disc haemorrhages or vascular changes. The underlying trend of vascular and haemorrhagic changes in glaucoma are demonstrated in this sample, which is in general agreement with previous studies. The high percentage of optic disc haemorrhages in low tension glaucoma is highlighted. The presence of microaneurysms and nerve fibre layer haemorrhages is interesting but of unknown significance.

Aneurysm↗
PubMed1995

Comparison of stereo optic disc photographs from the Nidek 3-Dx and Zeiss retinal cameras.

OBJECTIVE: To compare the Zeiss retinal camera with the Nidek 3-Dx camera for photographic quality and stereo separation. SUBJECTS: Eleven subjects (22 eyes) were selected from patients referred for optic disc photography. METHODS: The subjects were photographed using the Nidek 3-Dx camera for simultaneous stereo photographs, and the 30 degrees field and 15 degrees field settings on the Zeiss retinal camera for sequential stereo photographs. Four ophthalmologists qualitatively scored the photographs on a five-point scale for stereo separation and photographic resolution and sharpness. The results from the four observers were averaged and the Friedman two-way analysis of variance used to analyse the results. CONCLUSIONS: It was found that the stereo separation is significantly better using the Nidek camera when compared with both the 30 degrees and 15 degrees Zeiss results. There was no significant difference in photographic quality between the Nidek and Zeiss 30 degrees photographs. It was also found that the Zeiss 30 degrees images had a significantly higher quality than the Zeiss 15 degrees, which contradicted previous results.

Analysis of Variance↗
PubMed1994

Symptoms and signs of retinal disease.

Of all the diseases of the eye, the retinal disorders are perhaps the most frequently misdiagnosed by the general medical community. The content of this article is restricted to retinal diseases and the importance of symptoms and signs in their accurate diagnosis.

Fluorescein Angiography↗
PubMed1993

An improved method of densitometry of red-free retinal nerve fibre layer photographs.

The red-free negatives of 53 right eyes (30 normal eyes and 23 glaucomatous eyes) and 51 left eyes (32 normal eyes and 19 glaucomatous eyes) were analysed using two different image densitometry techniques. The first technique measured the density from rectangular sample areas, while the second measured density from sector-shaped sample areas which more closely follow the course of the nerve fibres in the retina. Indices which measured the deviation of the data from a clinically determined normal 'gold standard' were calculated, and were used to determine the optimum sensitivity and specificity in separating normal from glaucomatous eyes. There is a significant difference between the data from the normal and glaucomatous groups of eyes, when measured from the sector sample areas. The relative efficacy of this technique is also shown by the improved values of sensitivity (from 42%-70% to 70%-91%), although specificity remained fairly constant (from 66%-83% to 62%-88%).

Densitometry↗
PubMed1992

Correlations between densitometry of red-free photographs and reflectometry with the scanning laser ophthalmoscope in normal subjects and glaucoma patients.

OBJECTIVE: To compare image measurements of the retina produced by scanning laser ophthalmoscopy with those from red-free photographs (RFP) of the nerve fibre layer. SUBJECTS: The left eyes of 23 subjects (10 normal, 7 glaucoma suspect and 6 glaucomatous) were included in this study. METHOD: All the eyes were photographed using standard red-free photography, and images of the retina were digitised directly from the SLO. RESULTS: The correlation coefficient for all except three subjects was > 0.45, and the probability (p) that R = 0 was < 0.05 in all but 5 eyes. CONCLUSIONS: The data indicate that variations in retinal surface reflectivity as measured by the SLO are similar to those recorded on negative film during RFP. This further suggests that the SLO can be useful for making objective measurements of the RNFL, without the intermediate and variable steps of photography.

Densitometry↗
PubMed1992

Use of unsharp masks with high-contrast retinal nerve fibre layer photographs.

Retinal nerve fibre layer (RNFL) photography is an established and integral tool in the management of ocular hypertensives and glaucoma suspects, and in assessing the management of glaucoma in an ophthalmic practice. When RNFL negatives are viewed for analysis, high-contrast negatives yield the most information. When positive prints are subsequently requested, the RNFL negatives are difficult to print. The use of an unsharp mask facilitates the transfer of all the high-contrast negative density range to the print. The use of an unsharp mask has been simplified so that it is quick and efficient and can be adapted for high-contrast negatives other than RNFL images.

Glaucoma↗
PubMed1992

Variable angle retinal nerve fibre layer photography: a review.

Optic disc and retinal nerve fibre layer (RNFL) photography have been an integral part of the routine screening of glaucoma patients, ocular hypertensives and glaucoma suspects in Perth since 1979. During this period 60 degrees, 40 degrees, 30 degrees and 8 degrees angles of view were examined for potential use in RNFL photography. The degree of dilation and media opacity is highly variable in glaucoma patients because of the age group involved and the miotic therapy. It was found that the 30 degree angle of view gave the most consistent results for routine RNFL photography. Ocular hypertensives tended to be of a lower mean age and 40 degrees wide angle photography was possible but required two different photographic techniques and was not continued. Both 60 degrees and high-magnification RNFL photography are currently used only with selected patients for teaching and demonstration. A modified Hasselblad 120 roll film camera was used for high-resolution RNFL photography. The Hasselblad adaptors, high-resolution results and comparisons with wide-angle RNFL photographs are illustrated in this paper.

Fundus Oculi↗
PubMed1990

Simplification of unsharp masking in retinal nerve fibre layer photography.

Fundus photography is now an established tool for showing early changes in the retinal nerve fibre layer (RNFL). RNFL defects may precede glaucomatous visual field defects by up to five years and any improvement in photography should aid RNFL defect analysis. We have found that the use of an unsharp mask has helped to visualise the RNFL and by using readily available darkroom materials the process of unsharp mask preparation has been simplified.

Densitometry↗
PubMed1990

A study of variance in densitometry of retinal nerve fiber layer photographs in normals and glaucoma suspects.

The main object of this research was to develop a reliable method of screening glaucoma suspects and patients for early loss of or changes in the retinal nerve fiber layer (RNFL). This study quantifies the variances due to photography, digitizing, and analysis of red-free photographs of the RNFL. The influence of pupil size, optic disc position and eye movements, film processing, digitizing, and intra- and interphotographic-session and intra- and interoperator variances were established. It was found that pupils needed to be dilated to at least 6 mm, that the optic disc had to be positioned in a standardized area in the negative, that the head of the subject had to remain still during photography, and that film processing and digitizing of the negative needed to be strictly controlled to minimize the variance in collection of densitometry data from RNFL red-free photographs. It was established that focusing of the negatives during digitization was not crucial. Criteria were defined for acceptable negatives. Interphotographic-session and intraoperator variances were not significant in most cases when negatives were digitized to these criteria. Analysis of interphotographic-session variance showed that there were still some factors in photography, film processing, and/or image digitizing that were not sufficiently controlled for long-term follow-up without normalization of the data. Densitometry data gathered using the established protocol, from negatives of 71 subjects were analyzed; best sensitivity and specificity rates of 80% and 100%, respectively, were achieved for the diagnosis of glaucoma.

Adult↗