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Top-ten 2010 Annual Scientific Congress of the Royal Australia and New Zealand College of Ophthalmologists
Adelaide, South Australia, November 20-24
- Claude Burgoyne (Portland, Oregon; Glaucoma Update Lecture),
New Targets for SDOCT Imaging of the Optic Nerve Head in Glaucoma
This paper summarized a recent series of publications on deep optic nerve head imaging using Spectral Domain Optical Coherence Tomography (SDOCT) and suggested that these and recent publications from other groups suggest the anterior lamina cribrosa and scleral surfaces as well as optic disc margin anatomy are increasingly well visualized using enhanced depth imaging and longer wavelengths. He as well presented new data supporting age-related differences in deep ONH SDOCT parameters at the onset of Confocal Scanning Laser Tomographic surface change in the experimental glaucoma model." - Jamie Craig (Adelaide, Ida Mann Lecture), Pseudoexfoliation syndrome
and glaucoma susceptibility under the microscope
We have utilised cutting edge technologies such as genome wide association studies (GWAS) to provide new advances in the understanding of the pathology of pseudoexfoliation syndrome (PEX), and open angle glaucoma susceptibility. Data from large numbers of Australian individuals has led to the identification of important susceptibility genes for glaucoma traits. For the further study of PEX, we developed a technique to surgically isolate the material, and have used a combination of proteomics, and new imaging techniques such as atomic force microscopy (AFM) and Matrix-assisted laser desorption/ionisation (MALDI). These methods have shed new light on the complex protein interactions in PEX material and their distribution on the lens capsule. The methodology of GWAS, proteomics, AFM and MALDI will be explained in an approachable way, an interpretation of the results to date will be provided, and their potential for future impact on clinical practice considered. - Bill Morgan (Perth), Change in intraocular pressure is a major
determinant of retinal vein pulsation properties.
Following on from observations that the force required to induce retinal venous pulsation is a significant predictor of glaucoma progression, we re-examined subjects at a one year interval following an IOP change. Multivariate linear regression analysis demonstrated that change in mean ODF was significantly associated with change in intraocular pressure (coefficient = 0.66 mmHg/mmHg, p=0.001) and on univariate analysis r = 0.56, p = 0.005. This suggests that measurement of this force may be a useful index of optic nerve response to IOP lowering therapy. - Evelyn O'Neill (Melbourne), Tracking Clinician Eye Movement in
Optic Disc Examination
This study compared visual gaze behaviour of glaucoma subspecialists with ophthalmology trainees during optic disc and retinal nerve fibre layer (RNFL) diagnostic examination for glaucoma. We found glaucoma subspecialists adopt more systematic and ordered gaze behaviour patterns and spent longer time observing areas with the greatest likelihood of pathology (superior and inferior poles of the optic nerve head and adjacent RNFL) when compared to trainees. It remains to be elucidated whether incorporating systematic viewing behaviour of the optic disc and RNFL into teaching programs for trainees may expedite their acquisition of accurate and efficient glaucoma diagnosis skills. - Andreas Ebneter (Adelaide): Hyperglycaemia is Neuroprotective
in a Rat Model of Experimental Glaucoma
Two weeks after induction of ocular hypertension by laser photocoagulation of the trabecular meshwork, the amount of optic nerve damage and ganglion cell loss was compared between normoglycemic and hyperglycemic rats. Hyperglycemia significantly delayed retinal ganglion cell death and reduced the axonal loss by approximately 50% at two weeks. A bioenergetic approach to delay neurodegeneration seems promising and is worth further pursuit. - Fleur O'Hare (Melbourne): Temporal processing deficits in individuals
with primary open angle glaucoma
In a prospective study examining auditory function in 27 open angle glaucoma patients and 27 age matched controls it was found that a significant proportion of the glaucoma group had abnormal auditory temporal processing ability (p=0.012). Poor temporal processing was found to be associated with delayed neural conduction times and impaired speech recognition, exemplified under challenging listening conditions, in this glaucoma group. These data provide the first indication of auditory neuropathy in open angle glaucoma and point to neuronal susceptibility outside the visual system. - John Landers (Adelaide), The distribution and association of intraocular pressure in Indigenous Australians within Central Australia The IOP of indigenous Australians is lower than any other racial group previously published. This may relate to the low CCT readings found among this population. Clinicians will need to bear this in mind when examining indigenous Australians and make appropriate allowances for the measured IOP.
- George Kong (Melbourne): Mitochondrial impairment results in
increased susceptibility to injury in retinal neurons
Acquired mitochondrial DNA (mtDNA) mutations in neurons and other tissues are a hallmark of biological aging. Our study found that an increase in mtDNA mutations in a transgenetic mouse model significantly increased the susceptibility of retinal ganglion cells to intraocular pressure injury. This study suggests impairment of mitochondria can be a potential novel mechanism whereby increasing age can predispose to glaucoma. - George Kong (Melbourne): Why is the disc missed?
The skill of accurately assessing structural changes at the optic disc is critical for diagnosing and managing glaucoma, therefore we sought to extrapolate the factors that contribute to errors in assessing glaucoma risk. We found trainees underestimate glaucoma likelihood in 1 in 5 discs, are twice as likely to underestimate than overestimate glaucoma likelihood and errors in CDR, RNFL, rim loss and hemorrhage assessment are key factors that lead to underestimation. This study is important in guiding the development of optic disc teaching programs in the future. - John Landers (Adelaide), The prevalence pseudoexfoliation and
glaucoma in Indigenous Australians within Central Australia
The prevalence of open-angle glaucoma among indigenous Australians within central Australia was 0.52% for those aged ≥40 years. After adjustment for the age distribution of our sample, this is 1/3 the prevalence seen among the non-indigenous Australian population. This is noteworthy given the high prevalence of ocular parameters considered to be associated with glaucoma, such as PXF which was 5.9% amongst this group.
