(IGR: 13-4) | International Glaucoma Review #

Top-ten Annual Scientific Congress of the RANZCO
November 19-22, 2011 Canberra, Australia

Over the last few decades, ophthalmology has witnessed an explosion of new imaging and diagnostic devices that are touted as being able to detect glaucoma at its earliest, 'most treatable' stage. Other fields in medicine are also pursuing parallel approaches, most notably in oncology, where high-resolution CT scanning is touted as detecting lung cancer at its earliest 'most treatable' stage. Unfortunately the evidence that such an approach actually saves lives (in the case of lung cancer) or prevents blindness (in the case of glaucoma) is lacking. Indeed, after 40 years of screening studies in lung cancer, it is only this year that a large decade-long study has begun to show convincing evidence that screening CT scans save lives. The paradox of early detection strategies is that we frequently detect artifact or slowly-progressive disease that will never affect our patients. Ophthalmology should draw lessons from other fields of medicine and recognize that technologies like OCT are poorly-suited for widespread glaucoma screening and are likely to over-diagnose patients with optic nerve or RNFL changes that will never lead to visual impairment. (James Brandt, Davis, California, USA)

MAST is a clinical audit to assess patient self-declared convenience and tolerability when medications were switched to a fixed dose combination. This audit represents real life: 819 patients were followed for a mean of 179 days. Convenience improved in 69% and tolerability in 32% of patients. Having excluded regression to the mean, mean IOP fell from 17.5 (± 0.2) to 15.5 (± 0.1) mmHg. The number and severity of co-morbidities did not influence the result. (Ivan Goldberg, Sydney, Australia)

The PhNR amplitude (the photopic negative response) of the ERG is significantly reduced in patients with elevated intraocular pressures, particularly above 30 mmHg. This observation warrants further investigation. (Nuwan Niyadurupola, Melbourne, Australia)

Ten years ago, the Ocular Hypertension Treatment Study (OHTS) demonstrated that central corneal thickness (CCT) is a potent predictive factor for the development of primary open-angle glaucoma (POAG). Was this finding purely the result of CCT's influence on intraocular pressure measurement, or is something more going on? There is increasing evidence that CCT is a surrogate (a biomarker) for other aspects of glaucoma susceptibility. At this point physicians should not 'correct' IOP measurements for CCT but rather interpret the patient's global risk for glaucoma or disease progression taking into consideration CCT. Stratifying CCT into 'thin' (<520 microns), 'average' (520-580) and 'thick' (>580) but not correcting tonometry measurements is probably the best clinical approach until we understand more. The next decade of research into the biomechanics of the eye itself, alongside molecular genetics of CCT should provide further insight into the underlying pathophysiology of POAG. (James Brandt, Davis, California, USA)

Long term use of topical prostaglandin analogues results in some thinning of the central cornea. An average reduction in corneal thickness of 17 microns over several years was noted. This may have implications regarding interpretation of clinical trials. (Deepak Viswanathan, Sydney, Australia)

This update on the Australian and New Zealand's registry of advanced glaucoma described the genes TMCO1 and CDKN2B as having high association with advanced glaucoma on genome-wide association studies. (Jamie Craig, Adelaide, Australia)

Thinning of the nerve fibre layer and structural optic disc changes after acute angle-closure similar to those seen in chronic glaucoma were noted in this case series. (Colin Clement, Sydney, Australia and London, UK)

This study looked at the CSF pressure pulse, intraocular pressure pulse and vein pulsation pulsation timing in a group of neurosurgical patients with continuous intracranial pressure monitors. Venous collapse was found to be in time with intraocular pressure diastole and CSF pressure diastole demonstrating that CSF pressure pulsation is driving venous pulsation through enhancement of the translamina pressure gradient. (William Morgan, Perth, Australia)

In a genome wide association study (GWAS) on an Australian population with angle closure glaucoma no statistically significant single nucleotide polymorphisms (SNPs) were identified; however, in a larger Nepalese GWAS, several significant SNPs were detected. A significant Gino Myod association was found in the Nepalese patients only for a gene DDX43 and not in the Australian subjects with Primary Angle Closure Glaucoma. (Mona Awadalla, Adelaide, Australia)

Glucose is a powerful neuroprotectant against ischaemic retinal injury. The neuroprotective effect is partly due to ATP production via anaerobic glycolysis, and partly due to reducing agent production via the pentose phosphate pathway. (Guoge Han, Adelaide, Australia)