15 June 2022
Martin Long encouraged optometrists to look for imbalance within the eye as part of a session devoted to optical coherence tomography (OCT) interpretation at 100% Optical (London ExCel, 23-25 April).
The director of professional education at Heidelberg Engineering discussed his approach to utilising the imaging device during his presentation OCT interpretation uncovered – glaucoma and beyond.
Long noted that in a patient with glaucoma, the neuroretinal rim thins, while in early cases of glaucoma, a superior nasal step is visible.
“I am always looking for imbalance within the eye,” Long shared.
When assessing a scan for signs of glaucoma, there are three areas that Long focuses on: the shape of the neuroretinal rim, the nerve fibre layer and the posterior pole.
Long noted that within the ganglion cell layer of a normal eye, there is a red ring of parafoveal ganglion cells.
A notch or asymmetry on the parafoveal ring may be an early sign of glaucoma, he added.
Long observed that there is a correlation between visual field findings and ocular structure revealed by an OCT scan.
However, it may be possible to notice earlier changes in an OCT image than in visual fields.
On the question of whether visual fields are necessary, Long emphasised the importance of understanding what the patient is seeing.
“We can’t get rid of visual fields. We’ve got to know what the patient’s visual function is,” he said.
Long shared that he is cautious about relying solely on normative data when interpreting OCT scans.
He noted there is a wide range of ‘normal’ retinal nerve fibre layers, and some patients can lose a third of their nerve fibre layer while still within green levels.
“It’s really a good idea to look at the profile of the nerve fibre layer to find the earlier stages of defect,” Long emphasised.
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