Wielding the power of OCT

By Dr Chris Murphy

A one-off, all-day workshop providing a full overview of OCT technology and its clinical uses was arranged immediately before the CCLS one-day conference on Saturday 17 March 2018.

More and more optometry practices across the country are either considering or have purchased OCT machines. OCT investigations and OCT-assisted monitoring lead to a dramatic improvement in clinical care, so the board of CCLS thought it was timely to arrange a workshop to provide an insight into OCT technology and the interpretation of results.

I opened the workshop and presented the first lecture, which discussed the basics of OCT technology: how the initial time domain technology created a relatively poor image and how technological advances have led to the newer spectral domain technology, which is now the technology of choice for nearly all OCT’s on the market. I also discussed swept-source OCT technology, the latest advancement, which is more expensive but has a number of benefits, such as greater clarity of images and greater penetration, allowing the choroidal vasculature to be visualised. While this technology is currently only available with the Topcon Atlantis OCT machine, other manufacturers are in the process of developing their own swept-source OCT machines, which should be available soon.

Dr Jesse Gale, an ophthalmologist and glaucoma subspecialist from Wellington, then provided a comprehensive overview of OCT use in the diagnosis and management of glaucoma. He gave many helpful hints about how to maximise the use of OCT in this area and interpret the glaucoma assessment printout. This allows for a much more accurate diagnosis, and thus management of the disease, rather than the simple “red is bad, green is good” guide. Jesse then went on to cover many of the pitfalls of glaucoma and ocular hypertensive monitoring techniques and reinforced appropriate referral guidelines. He discussed the benefits and weaknesses of some scans, including ganglion cell patterns, which are available with some machines such as Zeiss’ Cirrus, and the need to incorporate the information into an overall glaucoma assessment. He ended his presentation with a look at where OCT can be helpful in neuro-ophthalmology diagnosis, such as identifying papilloedema.

This was followed by an hour-long lunch with much socialising and catching up with colleagues from around the country.

I then presented another lecture, this time on the uses of OCT in the anterior segment, discussing the assessment of the angle in multiple axes, which the new swept-source OCT scans do particularly well, and providing some examples of corneal surgery where the depth and accuracy of the incisions can be easily assessed. As an aside, at the request of the CCLS President Jagrut Lallu, I also discussed the current uses of Avastin in the treatment of corneal neovascularisation, which is a very difficult condition to treat. Examples include vascularisation of the cornea from severe limbal vernal keratoconjunctivitis or vascularising hydrops. Avastin is a simple, inexpensive and effective treatment and is now available publicly from many hospital eye departments including Waikato.

The next speaker, Richard Johnson, a well-known optometrist working in the Greenlane Clinical Centre in Auckland, gave an informative and entertaining lecture on OCT uses in medical retina treatment, in particular, macular assessment. He covered many of the common conditions that optometrists are likely to encounter, explaining the “normal range”, which could not be assessed before OCT scans were available.

Complementing Richard’s talk was a presentation by Auckland-based ophthalmologist Dr Andrew Riley, who gave a comprehensive review of medical retina conditions, including macular pathology, treatment and referral guidelines. In a wide-ranging and engaging talk, Andrew also discussed OCT assessment of vitreoretinal conditions and their treatment.

On behalf of the CCLS board, I would like to take this opportunity to thank the speakers for their time and efforts, the Capital Vision Research Trust for the faculty and the 53 attendees for their participation. We hope you found it useful for your continuing clinical practice.

Dr Chris Murphy is a Hamilton-based ophthalmologist and CCLS councillor.