Australian Vision Convention: Awesome Learning

GLAUCOMA

The progressive neurodegenerative disorder known as glaucoma affects 1.9% of the population; 5% are bilaterally blind, 10% are partially sighted, and 14% are blind in one eye. In a presentation on Recent developments in treatment of glaucoma, Dr Frank Howes, Director and Principal Surgeon at the Eye and Laser Centre on the Gold Coast, reminded his audience that age is a major risk factor for this disease. One in 10,000 babies have glaucoma; one in 200 people have glaucoma by the age of 40; and one in eight have it by the age of 80.

He complimented the manufacturing companies involved in the spectacular nanoengineering development work in minimally invasive surgical devices

Medications can either lower pressure, which is the only proven method to reduce the rate of loss in this incurable progressive disease, or make the optic nerve more resistant to metabolic process of the disease – otherwise known as neuroprotection.

Advances in glaucoma surgery, currently in the realm of so-called “minimally invasive surgery”, have been investigated and applied in an attempt to find safer procedures than trabeculectomy.

Dr Howes pointed out that both the currently available trabecular bypass MIGS devices and the injecting systems used to position them are “pretty smart” because, as minimally traumatic surgeries they leave the natural anatomy intact, promoting the natural pressure control systems and preserving the potential for future treatment options, including drug delivery devices.

He complimented the manufacturing companies involved in the spectacular nano-engineering development work in minimally invasive surgical devices and drew attention to the latest developments from Glaukos – the ‘iStent Infinite’, expected to be available in Australia in 2022, which allows three bypass stents to be inserted into the trabecular meshwork for enhancement of aqueous outflow across five to six clock hours of Schlemm’s canal. Additionally, Glaukos has developed the iDose, a slow drug eluting device, which he said, “has great potential for the future for slow release micro-dosing of medication”. Dr Howes said blending of micro-invasive surgery with micro-dose medicine is the newest technique for managing glaucoma.

As a life-long condition, many people with glaucoma are treated over the years with topical drugs containing preservatives and active ingredients that can cause ocular surface disease (OSD). The incidence of OSD increases with time as patients require multiple, and combination therapies for management. As a result of OSD, patients become uncomfortable and are less likely to be compliant with their medications. Their glaucoma progresses and more aggressive management is required.

He explained that minimally invasive surgeries can reduce the incidence of OSD by the procedures themselves and if further drug assistance is required, by delivering these in much less concentrated form, directly into the anterior chamber and aqueous, by slowrelease pellets or drug eluting devices, either into the anterior chamber (AC) or attached to the AC angle tissues.

Allergan, PolyActiva and Glaukos all have devices in development for intracameral elution and micro-dosing, introduced into the AC, either by small gauge needle or into the angle by intra-cameral introducing devices. Prostaglandin analogs are the common drugs put into these devices – and they can last up to two years as shown by the current data from the Glaukos iDose research. Some other drugs, in particular, the newer IOP lowering and neuroprotective agents – the Rhokinase inhibitors – are under consideration for microdose elution.

“Predicted danger zones for these devices will be endothelial cell loss, iritis, peripheral anterior synechiae, granuloma formation and pupil distortion… Studies to this point show that dangers are minimal… the work so far suggests these devices are efficacious, promote tolerance, have limited side effects, and their internal nature promotes compliance,” he said.

Dr Nick Andrew (Sight Specialists, Gold Coast) presented Lessons in glaucoma management from the coalface.

“To do a really great job of glaucoma requires the right mindset – you need to find joy in attention to detail – by appreciating the nuances of management you can find the best individual treatment for your patients,” said Dr Howes.

Dr Andrew pointed to the myriad studies that can direct management but said it is vital that you look carefully at the data (not just the publication taglines), diagnose and classify patients correctly, and take into account the patient’s lifestyle – only then can you truly customise their care.

While some may be inclined to treat at all costs, he said the burden of treatment must always be less than the burden of disease – so consider the consequences and side-effects of your treatments, weighed up against your patient’s risk of glaucoma visual disability.

On the relationship between glaucoma and cataract Dr Andrew said, “we have good prospective evidence that both open and narrow angle glaucoma patients experience pressure drop from cataract surgery alone”. However, post-operative pressure spikes are common and the COMPASS study showed us that pressure control actually declines in 38% of open angle glaucoma patients who undergo cataract surgery without an adjunctive MIGS procedure, due to the inflammatory stimulus to the eye, which stresses the already brittle outflow system.

Dr Andrew said there is strong evidence that phacoemulsification combined with MIGS is superior to phacoemulsification alone, in terms of pressure lowering, duration of benefit, and medication reduction.

“If you are going to perform cataract surgery in a patient dependent on glaucoma medications, then it’s a shame not to do MIGS at the same time, in fact such management would likely be doing the patient a disservice. In this situation the question is not whether I should perform MIGS, but which MIGS procedure should I perform?”

There is no prospective evidence for phacoemulsification in primary angle closure suspects. However, there is some evidence for phacoemulsification in primary angle closure and primary angle closure glaucoma.

Narrow angle patients with early cataract are often considered for cataract surgery but these are “high stakes cataract operations” due to the increased risk of refractive surprise. This is due to a higher chance of formula error, the dramatic impact of effective lens position in the setting of a high power intraocular lens (IOL), and imperfect tolerance levels in IOL manufacturing.

“If you get a refractive surprise then a piggyback IOL is not ideal – the indication for cataract surgery was angle crowding, therefore there isn’t much room for two pseudophakic lenses.” Dr Andrew said that lens exchange or laser vision correction are usually more appropriate in this situation.

ADVANCED THERAPEUTICS FOR KERATITIS

Associate Professor Colin Chan spoke about the ‘art and craft of therapeutic management’ when treating people with unusual keratitis – ie., rare, one we’re quite familiar with that appears in unusual form, or one that does not respond therapeutically to traditional treatment.

As a rule of thumb, he said if you can’t be definitive about the keratitis you’re looking at, the next best thing is to try to group it into a ‘type’ of keratitis – this will guide your approach to management.

He presented his own self-described “bad acronyms” for categorising keratitis:

Is it microbial?

If not is it:

Dangerous/ulcerative keratitis (DUKs),

Small multi-opacity keratitis (SMOKS),

Peripheral allergic keratitius (PAKs), or

Paracentral opacity keratitis (POKs).

If in doubt about whether the keratitis you’re looking at is microbial or not, A/Prof Chan said, “Treat first, ask later”. There is minimal downside to starting the patient on intensive ciprofloxin – it’s a safer approach and it’s wiser than waiting.

Only initiate steroids if you’re sure the keratitis is not microbial. The best way to begin is gently, with a low strength steroid – dosed once or twice daily and combined with careful observation.

“Sometimes the type of keratitis will become obvious over time. You can slowly increase the steroid or increase the dosage under observation if needed.”

A/Prof Chan cautioned delegates new to therapeutics, to “take it slowly” until they feel comfortable prescribing and always refer on to an ophthalmologist if unsure.

In diagnosing, A/Prof Chan said blood tests aren’t particularly helpful although they can be useful as a process of exclusion for disease such as herpes simplex virus, syphilis, and tuberculosis (TB). However, it’s important to know that a negative PCR or swab for adenovirus doesn’t necessarily mean it’s not an adenovirus.

When diagnosing keratitis, you do need to be able to exclude DUKS, the symptoms for which can include peripheral ulcerative keratitis, rheumatoid arthritis (over 10-20 years), Moorens (PUK in the absence of rheumatoid arthritis); vernal ulcers (atrophic) and neurotrophic keratitis (patient will have past history of shingles).

He said DUKS with corneal opacity and thinning, and induced astigmatism indicates “a really bad keratitis”. The patient will either be in immense pain, or surprisingly may have no pain at all.

While normal epithelium will heal within a week, severe cases of DUKS will resist normal treatment three to four weeks after commencing.

“The whole focus is to close your epithelial defect, which will otherwise become a source for melting enzymes – and eventually the cornea melts,” he explained.

Treat intensively with preservative free lubricants, topical anti-inflammatories, steroids (be gentle with these, you don’t want to retard epithelial closure) and refer on to an ophthalmologist/corneal surgeon to treat the underlying cause.”

Treatments to prevent corneal melting/ thinning are oral tetracyclines, serum autologous tears, and conjunctival resection/recession.

Some keratitis will defy all logical treatment – recurrent HSV being the most common. A/Prof Chan recommended optometrists approach these patients holistically and manage the eye as an ecosystem. The tips he provided can be summarised as follows:

• Manage all the co-existent dry eye/ocular surface disease with medications and/or supplements that do not exacerbate the keratitis.
• Think outside the square to try different formulations of the same medication; try weird doses; try new therapies as they emerge even if they’re not specifically for that disease,
• Re-think the past – challenge previous therapeutic assumptions – they may be robbing you of a therapy you could now be using,
• In some cases you will need to accept the necessary evil of steroids, perhaps long-term – myths about the risks of steroids aren’t necessarily true, especially for low dosages in consultation with the ophthalmologist, and finally
• As much as it can take time to ask a patient how they are, you need to know about their health outside of the eye. Ask about other (new) medications, disease and environmental factors.

A/Prof Chan pointed to increasing evidence in peer reviewed published literature that the gut microbiome affects the rest of the body and eyes. “The gut and inflammatory disease may be linked. Individualisation of medicine will be the great differentiator of the 21st century,” he said in his concluding statement.

NASOLACRIMAL DISEASE AND MANAGEMENT

Dr Lindsay McGrath (Brisbane) presented Cry me a river – nasolacrimal disease and management.

There is a complex interaction of voluntary and involuntary reflexes that keep the eyes hydrated. Pathology along the pathway at any point can cause over or under production/drainage of tears. Perhaps for this reason, it is common to see patients present with a watery eye – approximately 50% of people experience mild intermittent symptoms of epiphora. Once treated, Dr McGrath said these patients can be the happiest you could ever have.

Even though logic tells us that gravity would pull more tears into the bottom canaliculus, both the top and bottom canaliculi are equally important for drainage of tears.

When patients present with epiphora, it is very important to take a thorough history and examine them comprehensively – they will require a full work up and can require surgery, depending on signs and symptoms.

Patient evaluation should consider whether the epiphora is unilateral/bilateral; any aggravating/relieving factors; how it affects the patient day-to-day; associated symptoms – pain/itch/discharge; prior medical history (cancer/automimmune disease/thyroid), and any prior surgical history around the eyes (sinus, nasal fracture/medications).

A comprehensive examination with the slit lamp followed by fluorescein dye, in conjunction with the evaluation, will help determine the cause of the watery eye and direct management. Look at the lids, check the tone, look for aberrant regeneration, tears coming up, trichiasis, blepharitis, and lacrimal sac swelling; check the nose for masses and inflammation; check for megalo-caruncle obstructing the puncta; the size and position of the globe; the volume and quality of tears, conjunctiva appearance, foreign bodies, and the cornea for punctated erosions/abrasions etc.

The more common causes of watery eye are disorders of the punctum, the canaliculi, and lacrimal sac. Among older women, one of the most common causes is the narrowing and closing of the ducts; previous surgery can also contribute. People with inflammatory disease and systemic disease are predisposed as well as people with tumours in the nose or the medial canthal area. With nasolacrimal duct obstruction, patients are at higher risk of infection so they need to be treated with antibiotics quickly, and admission to hospital is sometimes required for intravenous antibiotics. Newborns can also develop nasolacrimal duct obstruction. Be suspicious of blood coming through the punctum – this is a red flag for malignancy.

Dacryocystorhinostomy (DCR) is the gold standard treatment for nasolacrimal duct obstruction in adults. When the canaliculi is damaged by disease or trauma, a tear bypass operation with an artificial tear conduit is indicated. This may also be necessary if the lacrimal pump mechanism is ineffective in tear elimination or with multiple failed DCRs.

AVC IN 2022

Cathryn Baker, CEO of Optometry Queensland/Northern Territory said the Association was thrilled with the feedback received following this year’s AVC, and that it will return to the Gold Coast in 2022 as a hybrid event, from 9–10 April.