Richard L. Cooper

Aqueous humor catecholamines

The catecholamines norepinephrine, (NE) epinephrine (E) and dopamine (DA) were detected for the first time in the aqueous humor of humans under general anesthesia and monkeys under ketamine. The catecholamine levels in aqueous humor of 9 humans were assayed. NE was 0.796 +/- 0.457 ng./ml., E ranged between 0 and 0.132 ng./ml. in 4 out of 9 subjects, and DA was found in 2 of the 9 eyes. (0. 123ng ./ml. and 0. 318ng ./ml..) Plasma levels were measured in 8 of the human subjects at the time of aqueous sampling -NE was 0.311 +/- 0.171, E ranged between 0 and 0.097 (4 out of 8 subjects) and DA was detected in one subject- 0.037 ng./ml.. Monkey aqueous levels were NE:2.843 +/- 0.668 and DA:0.462 +/- 0.177 ng./ml., with an intact iris. (N = 8 eyes.) NE was 0.497 +/- 0.049, and DA 0.426 +/- 0.218 ng./ml. after total iridectomy. (N = 4 eyes) E was not detected in the monkey under these conditions. Whilst NE may be produced in part by the iris, DA levels were not affected by iridectomy. This implies that DA may be produced by structures unrelated to sympathetic nerve endings of the iris in the anterior segment of the non-human primate eye, perhaps by diffusion from the ciliary body or retina. Ketamine is known to inhibit catecholamine uptake, which may explain the high levels measured in the monkey. Human aqueous catecholamine levels measured under anesthesia may be affected by a variety of the drugs used. It is postulated that dopaminergic neurones and associated receptors may be present in the anterior segment of the eye. This may explain the presence of aqueous humor dopamine and the effects of dopaminergic drugs on intraocular pressure.

Trends in Registered Blindness and its Causes over 19 Years in Western Australia

Purpose: To estimate the population-based incidence rates of blindness registration and their trends over time in Western Australia. Methods: A retrospective review was performed on all cases of bilateral blindness registered with the Association for the Blind of Western Australia between 1984 and 2002. The causes and mean age at blindness registration were ascertained and incidence rates of blindness due to various causes were calculated. Results: A total of 3852 blind certificates were examined. From 1984 to 1994, the annual incidence of registered bilateral blindness decreased significantly at an average rate of 9.4% per year (p < 0.0001), but then rose at a mean rate of 4.1% per year (p < 0.0001). ARMD blindness similarly fell by 8.9% per year (p < 0.0001), but then rose after 1994 by 4.5% per year (p < 0.0001). The incidence due to glaucoma decreased at an average rate of 10.3% per year (p < 0.0001) until 1994 and then rose at 7.4% per year at borderline significance (p = 0.025). Conclusions: There has been a nonlinear decrease in the incidence of registered blindness, in particular glaucoma-related blindness, in Western Australia. Rates of total registered blindness and that due to ARMD fell from 1984 to 1994, but have risen since.

The problem of overlapping glaucoma families in the Glaucoma Inheritance Study in Tasmania (GIST)

The Glaucoma Inheritance Study in Tasmania (GIST) is a population survey of Australias island state, Tasmania (population 450,000). Its aim is to find families with autosomal dominant, adult-onset, primary open angle glaucoma (POAG) suitable for genetic linkage analysis. POAG is relatively common, affecting around 3% of the Australian population. By finding the large families with POAG and identifying all the descendants in a captive population, it is possible that there may be overlap of different glaucoma pedigrees. Three of the first thirteen families in the study were composed of overlapping pedigrees. In one GIST family, GTas3, there has been intermarriage with other pedigrees with glaucoma on five occasions. The possibility of multiple genotypes was also reinforced by the inability to determine a single glaucoma phenotype in this family. When finding large families of POAG for linkage analysis, researchers must be aware of the risk of affected individuals inheriting their gene from the alternate parent. Thus, the alternate parents or their families must be examined, especially if the phenotype is atypical for the rest of the family.

Relationship between corneal thickness and optic disc damage in glaucoma

Background: Central corneal thickness (CCT) has been found to be a powerful predictor for the development of glaucoma in patients with ocular hypertension. This study aimed to determine whether CCT was also related to glaucoma severity.

Computerised densitometry of red-free retinal photographs correlated with automatic perimetry

An image analyser installed in a 16 bit personal computer was used to measure grey levels in red free photographs of normal and glaucomatous eyes. Regional photographic image intensity and density were correlated with Humphrey Field Analyser results for corresponding areas of visual field. Two methods for standardising photographic exposure by histogram equalisation and slide were compared in two groups of eyes from 13 subjects. For histogram equalisation, r2 varied from 0.16 to 0.29 for linear fits in temporal retinal quadrants. For the histogram slide, r2 varied between 0.19 to 0.45 for linear fits. Similar results were found for mean histogram equalised image intensity versus Humphrey Field Analyser global indices: Mean Deviation, (r2 = 0.27) and Pattern Standard Deviation, (r2 = 0.37). For histogram equalised image data, resistant line analysis showed a linear goodness of fit of 0.92 and for histogram slide goodness of fit was 0.97 for upper and 0.87 for lower temporal quadrants.

Wegener's granulomatosis presenting with painless bulbar-conjunctival ulcer and central retinal artery occlusion.

Herein an unusual case of Wegeners granulomatosis with a painless, bulbar‐conjunctival ulcer in the right eye is reported. Rapid disease progression occurred with central retinal artery occlusion in the fellow eye. Biopsy of the diseased conjunctiva confirmed the clinical diagnosis. The clinical and histopathological findings are discussed.

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.

Performance of two films for densitometry of retinal photographs

The relative performance was determined of two different photographic films (Kodak Panatomic-X and Kodak Technical Pan) for densitometry readings from retinal photographs of patients who had or were suspected of having glaucoma. The raw data from the two films were significantly different. The high contrast film was particularly sensitive to external variables; however, when normalised in terms of the standardised deviation, the data from the two films were comparable (P < 0.005). We also measured the pattern of nerve fibre layer loss using digital image analysis of red-free photographs of normal, ocular-hypertensive, glaucoma-suspect and glaucomatous eyes. Several mathematical techniques were used to characterise the data from each eye and then to compare these data to the mean photographic density of the normal eyes. Results showed that it was possible to separate normal eyes from glaucomatous eyes. The highest sensitivity achieved was 100% for right and 88% for left eyes, and the highest specificity was 100% for both eyes.

Tools for cup:disc ratio measurement.

to provide flicker-free stereoscopy. These polarized images are then filtered by polarized eyewear worn by the observer. The curser depth can be adjusted to coincide with Elschnig’s rim. Although linear cup and disc diameters at the depth of Elschnig’s rim were recorded for this experiment, a separate tool allows the observer to outline the neuroretinal rim as well as the inner margin of the disc. Image magnification was corrected on the basis of: keratometry readings; refraction; and camera specifications using established methods to provide scaled estimates of disc parameters. We found that assessment of VCDR using the hand-held Screen-Vu with Adobe Photoshop was highly concordant with the Z-screen and Cardiff Stereoscopic Viewing software (Table 1). Additionally, the use of a graticule attached to a 60-D lens was better correlated to stereoscopic analysis using custom software and Z-screen technology than stereoscopic planimetry using Adobe Photoshop. The primary advantage of the Z-screen over previous digital methods of disc assessment using optic disc images is that the user is able to accurately define the neuroretinal rim by contour at the depth of the scleral rim and the observer can pan over the images, zooming in on regions of interest. It is worth noting that with systems that use a cursor displayed to one eye, the psychophysical effect of retinal rivalry may make the cursor appear to fade. The Screen-Vu system is a relatively cheap method for obtaining excellent stereopsis of digital images, while the main benefit of the graticule attached to the 60-D lens is that reproducible optic nerve head measurements can be performed at the slit lamp. Overall, Tools for cup:disc ratio measurement

Investigation of the prevalence of the myocilin Q368STOP mutation in Ugandan glaucoma patients.

Acknowledgements We would like to thank the participants for their involvement, Assoc. Prof. David Mackey for his direction and advice, and Andrew Bell for his technical assistance. This work was supported by the Perth Eye Centre Pty Ltd, the Western Australian Lions Eye Institute, Christian Blind Mission International, the Glaucoma