EI panellists (L-R) Drs Shanu Subbiah (chair), Sophie Hill, Hannah Kersten, Narme Deva and Adam Watson with Prof Charles McGhee (speaking) and Dr William Cunningham

If one must give up a sunny Sunday in pursuit of education, the Auckland Museum offers a spectacular spot to absorb breakfast and information, fuelled by plenty of coffee. Using this bait, 10 of the Eye Institute’s 17 surgeons lured a large group of knowledge-hungry optometrists, many bleary eyed from the previous night of rugby excitement.

First up was Professor Helen Danesh-Meyer, eager to regale us with the perils of space travel’s impact on the fragile balance between intraocular pressure (IOP) and intracranial pressure (ICP). Astronauts returning from longer space missions experienced blurred distance and near vision. Despite being young and healthy, they were found to have optic disc swelling and hyperopic shift, accompanied by mild to moderately raised ICP. This led to further work on the role of translaminar pressure in glaucoma. Since an OCT machine was installed on the International Space Station (ISS) in 2013, disc swelling has been monitored in situ as well as cerebrospinal fluid by MRI upon return*.

This led to the Killer hypothesis, named after Dr Killer, who hypothesised there is a bottleneck of fluid in intracranial spaces. The translaminar pressure gradient between the eye and the brain may be responsible for some forms of glaucoma, particularly low pressure open-angle glaucoma in myopes. Perhaps the take-home message here is that myopes and those prone to headaches should avoid space travel!

Dr Graham Reeves looked at developing cataract in glaucoma and how the outcome of removing the lens may be different in different forms of glaucoma. In primary open-angle glaucoma (POAG), for example, removing the lens may not change the IOP but sometimes the decision of glaucoma surgery or removing the cataract first may come down to whether the cataract is obscuring the view of the retina or even how much the patient is suffering from glare sensitivity and loss of contrast.

Although minimally invasive glaucoma surgery (MIGS) has been around for a while now and caused a paradigm shift in thinking in glaucoma treatment, no single device has cornered the market because each has a profile appropriate to a specific type of glaucoma.

Delegates at the 2022 EI conference at the Auckland Museum conference venue

Flashing, one-night stands and consecutive cataract surgery

Dr Peter Hadden took a break from cataract surgery on penguins and tuatara to describe his experience of flashing. First, the answer to the age-old question of whether photopsia is singular or plural? It’s both, said Dr Hadden. He reminded us of benign entopic images such as Purkinje figures being shadows of vessels or Haidinger’s brushes (those yellow streaks best seen in low light) being a good test of the fovea that none of us managed to find in optometry school – though phosphenes from mechanical pressure in the dark was always a good measure of optometry students’ activity. The Stiles-Crawford effect (where light entering near the edge of the pupil appears less intense than through the centre) experienced when driving at night was generally regarded by students as being due to rather more unnatural causes.

On a more serious note, Dr Hadden said eye rubbing in babies may sometimes be a sign of blinding congenital conditions, where the phosphenes produced give visual stimulation that is otherwise lacking. Photopsia in ocular pathology can be indicative of carcinoma associated with retinopathy or a uveal melanoma, not forgetting that Moore’s lightning streaks are more often from a vitreous detachment. These are more like lightning at the temporal periphery and more obvious in the dark or with sudden movement of the eyes.

Dr Hadden also pointed out not all flashes are in the eye of the beholder – they can also be in the brain as psychotic visual hallucinations or zig-zag migraine streaks. Retinal migraines are characterised by repeat attacks, macular scotoma or blindness, usually lasting less than an hour and often associated with headache. It is important to rule out other ocular or structural vascular issues, he said.

Dr Shanu Subbiah temporarily set aside his MC duties to focus on the troubling question of sequential versus consecutive cataract surgery. While delaying surgery has been the standard practice, operating on both eyes together is becoming more popular, mainly because of the more efficient use of hospital resources. In Finland, 40-60% of patients have bilateral cataract surgery. The benefits to the patient are faster visual rehabilitation, reduced or no anisometropia (resulting in better stereopsis and reduced risk of falls) and fewer clinical visits post-surgery. However, risks do remain and if the surgery is difficult in one eye it is likely to be difficult in the other. The list of patient exclusion criteria includes previous laser vision correction, very dense cataract and shallow anterior chamber. In these circumstances, each eye requires a separate procedure.

Applying common stents

Dr Divya Perumal gave us the surgeon’s view of what is new in glaucoma surgery, noting that, “With more optometrists involved in co-management, you need to know this.” The glaucoma surgery videos that followed were enlightening for anyone engaged in co-management and whose breakfast was quite secure in their stomach.

Dr Divya Perumal presenting

In the panel discussion that followed, it was pointed out there is still a place for trabeculectomy, even with all the different MIGS options – different tools suit different tasks, according to the target pressures needed to stop glaucoma progression. It depends also on the amount of post-operative care required and how well the patient will cope.

Intriguingly Dr Subbiah contributed that surgeons regard cataract surgery as being like a one-night stand, whereas glaucoma surgeons know they are going to grow old with their patient!

Guttae, guttata, fritter or frittata?

What’s in a name? A vexing question, according to Dr Adam Watson, who revealed his pet hate is incorrect nomenclature. According to Dr Watson, gutta is a drop, guttae is more than one drop and guttata is not related to frittata but is an adjective used to describe, for example, a ‘guttate cornea’, which segued into his topic of Fuchs’ dystrophy. Although 3-4% of the population over 40 years old have some guttae in their cornea (particularly if they are smokers), those who progress to Fuchs’ dystrophy are likely to have an interaction of multiple genes which leads to cell dysfunction. Onset before 40 is likely to be a different disease or mutation.

Ultimately, the patient’s perception of how much of an issue it is will determine how much intervention is required, while urgency is determined by their age as well as corneal thickness changes. Dr Watson said medical treatment is often disappointing but surgical treatment is showing good results and still developing.

Dr Sophie Hill, the newest member of the Eye Institute team, was given the opportunity to discuss macular degeneration, after which Dr Narme Deva took over to inform us of the latest drugs and the anticipated increase in their accessibility. Faricimab (Vabysmo) gained FDA approval in January 2022 (and will be funded via the Pharmaceutical Benefits Scheme in Australia from Jan 2023). As usual, New Zealand lags a bit behind in approving this drug, which is anticipated will greatly extend the interval between injections, particularly for diabetic macular oedema. This is particularly prevalent in the working-age population, where the burden of frequent time off for medical treatment is greatest, with treatment fatigue commonly reducing compliance.

Dr Narme Deva discussing the latest medications available (sadly not necessarily in New Zealand)

Treatment for GA

With the holy grail of macular degeneration treatment being a medical response to geographic atrophy (GA), it was exciting to hear Eye Institute research manager Dr Hannah Kersten describe ONL1204-GA-001, one of the multicentre phase 1b clinical trials underway, with both Eye Institute in Auckland (led by Dr Deva) and Southern Eye in Christchurch among the study sites.

ONL1204 is peptide which blocks the Fas death receptor signalling pathway that leads to photoreceptor death and GA. The study is assessing the safety and tolerability, as well as efficacy measures, of two intravitreal injections of ONL1204, given three months apart. It requires motivated patients over 55 years old, who will be split into two treatment groups (lower dose and higher dose ONL1204) and a sham injection control group. Patients must have bilateral GA, secondary to dry age-related macular degeneration (with no history of wet AMD), of approximately one disc diameter in area.

Eye surgeons with heart

Dr Will Cunningham explained he was raised on corneal surgery by Professor Charles McGhee but “went to the dark side” of specialising in refractive and vitreoretinal surgery. He restored our faith by assuring us that while anterior surgeons regard themselves as movie stars and vitreoretinal surgeons as ‘backroom boys’, the new breed of vitreoretinal surgeons “have feelings and will listen”. Good to know!

Dr Cunningham then came out of the backroom to bust myths such as there being no evidence to suggest myopes who indulge in bungee jumping are at greater risk of retinal detachment. This is also good to know, as bungee jumping terrifies guide dogs! Retinoschisis, more commonly observed in hypermetropia, rarely causes vision loss and is generally not as progressive as a detachment. However, eye rubbing in keratoconics can increase risk of retinal detachment.

Refractive vitreoretinal surgery is a good solution for a patient who needs vitreoretinal surgery and cataract surgery since those not already developing a cataract will likely do so soon. It makes sense to do one operation with one recovery, which takes longer with dual pathology.

Corneal transplants in the 2020s is the domain of Prof McGhee, who specialises in grafting without actually using a graft. Handy when there is such a shortage of graft material around! The main change is the increase in the number of procedures, which have more than doubled in New Zealand in the last 30 years, although we also have only half the number of donors as grafts required. With the increase in population growth and more cataract surgery, there is an increased risk of endothelial decomposition. (Maybe cataract surgeons need to change their thinking on growing old with their patients.)

Keratoconus still demands the lion’s share of surgeries, but Fuchs’ endothelial dystrophy is becoming more common in the statistics, as well as regrafts. Prof McGhee pointed out the first graft is the most successful, with decreasing success rates with subsequent regrafts.

Closing the conference, Prof McGhee appealed to us to remind potential donors that just having it on their driver’s licence is not sufficient – they must advise their nearest and dearest of their wishes as family members must still consent to the deceased’s donation**.

*For more on the effects of space travel on the eye, see www.nzoptics.co.nz/articles/archive/orbits-in-orbit-the-weightless-eye

**For more on cornea donations, see www.nzoptics.co.nz/articles/archive/glazing-the-windows-to-the-soul

Naomi Meltzer has worked in optometry for more than 30 years and runs an independent practice in Auckland specialising in low-vision consultancy. She is a regular contributor to NZ Optics.