Pathological changes seen in glaucoma include: enlarged optic disc and disc cupping, pale discs, ragged disc rims, nerve fibre haorrhages (Drance haorrhages), and ‘wedge’ defects apparent in the nerve fibre layer. Unfortunately, many of those can be missed using an OCT.According to White, even the experts cannot agree on which imaging modalities are best for glaucoma diagnosis, even when their progression analysis features are used.{{quote-A:R-W:500-Q: It is getting more portable and cheaper all the time and also has the advantage of being able to see ‘behind’ the iris. }}He believes that the GDx scanning laser polarimeter is fading from use, the HRT scanning laser ophthalmoscope gives the best images but is not user-friendly nor especially repeatable, and the greatest advantages of OCT are its cross-sectioning and near ubiquity.Anterior segment OCT has significant utility in assessing the anterior chamber and its angle, but again White is of the opinion that you cannot beat gonioscopy in the hands of a competent practitioner.The high-frequency ultrasonic biomicroscope (UBM) is now used in a few specialised practices for anterior segment imaging but he notes that it is very operator dependent. However, it is getting more portable and cheaper all the time and also has the advantage of being able to see ‘behind’ the iris.White then posed the question – ‘Is OCT angiography (OCTA) the next big thing?’ Supporting its role is the correlation between peripapillary microvascular drop-out and glaucomatous damage, and the severity thereof (possibly better correlated than RNFL thickness loss).OCTA can also donstrate improved peripapillary microvascular perfusion when IOP is lowered, at least early in the disease. He concluded that multimodal imaging was still required currently, because no particular instrument or technology ‘does it all’ and none is better than the expert human eye.From the presentations and their reception, it was clear that Ophthalmology Updates! serves a purpose not met by any other meeting on offer.
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Clinical Associate Professor Andrew White B.Med. Sci(hons) MBBS PhD FRANZCO is a clinician scientist ophthalmologist at Westmead Hospital. His subspecialty interest is glaucoma. White was awarded First Class Honours in Medical Science in 1995 and a combined MBBS/ PhD degree in 2002 from the University of Sydney. He has research affiliations with the University of Sydney at both the Save Sight Institute and Westmead Institute for Medical Research, where he runs a laboratory developing new treatments for glaucoma. |
