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Feature

Inaugural conference brings clinicians together

30/08/2019By Lewis Williams PhD
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Alongside O=MEGA19’s trade fair, masterclasses and industry sponsored sessions, the Clinical Conference was held to support optometrists at all stages of their career. LEWIS WILLIAMS details some of the presentations delivered during the event.

Hosted by the newly merged Optometry Victoria South Australia, the inaugural O=MEGA Clinical Conference was designed to replace the long-established Southern Regional Congress (SRC). It was held at the Melbourne Convention and Exhibition Centre from 19-21 July 2019, alongside the trade show, dispensing master classes, a student careers expo and the remainder of the event.

The program was scheduled in a dual-stream format designed to meet the needs of optometrists, and featured both local and international presenters.

Glaucoma and age

Associate Professor Bang Bui from the University of Melbourne’s Department of Optometry and Vision Sciences delivered an erudite and detailed presentation on why older eyes are at greater risk of developing glaucoma.

To underline the importance of the topic, he gave the prevalence of glaucoma as 2-6%, subject to racial variations. This makes it the second largest cause of blindness worldwide.

He described glaucoma as a multifactorial condition that leads to progressive retinal ganglion cell (RGC) loss, gradual optic disc cupping and vision loss. The optic disc is the site of mechanical and vascular injury, especially in the disc’s inferotemporal quadrant. Research suggests that visual field changes were most likely in the area of the retina served by the beta-zone of the optic disc in which peripapillary atrophy (PPA) was greatest.

The numerous risk factors for glaucoma include: older age, thin central corneas, high intraocular pressure (IOP), optic nerve cupping and low ocular perfusion pressure (OPP). Glaucoma progression was related to age, IOP treatment, bilateral disease, exfoliation, and optic disc haemorrhages. Contributing factors include a history of cardiovascular disease, diabetes, myopia, hypertension, reduced corneal hysteresis and pseudoexfoliation.

It is known that lowering IOP, which remains the only modifiable factor, reduces the risk of development and progression of the disease. However, according to a 2008 study the contribution of IOP to the risk of glaucoma in some eyes might be small. It is now considered that IOP is only a small part of the story, but tonometers are not yet headed for the bin.

With advancing age the number of RGCs and axons declines, an effect confirmed by spectral domain optical coherence tomography (SD-OCT). Furthermore, with age the RGCs change shape, have fewer synapses and smaller dendritic arbors. While RGC function declines with age, the retinal function declines more. In other words, the RGCs may function better than expected.

It is thought that the better functioning of the inner retina reflects some sort of compensation. It might also be that the retina’s ability to compensate for ‘injury’ has reached capacity.

Unfortunately, there is also evidence that RGCs in older eyes are more sensitive to IOP elevation. They also show greater dysfunction and slower recovery. Age changes include: impaired vascular supply, poorer mitochondrial production along with increased oxidative stress, impaired endogenous (in-body or in-retina) protection, and increased stiffness of the extracellular matrix and tissue.



"The numerous risk factors for glaucoma include: older age, thin central corneas, high IOP, optic nerve cupping and low ocular perfusion pressure"
Bang Bui, associate professor, University of Melbourne

Low OPP, the difference between blood pressure and IOP, is a risk factor for glaucoma. Paradoxically, age-related vascular hypertension increases the risk of glaucoma, though not via IOP elevation. Generally, vascular hypertension impairs ocular blood supply. This means that despite the pressure elevation, less blood is actually delivered to the eye.

Chronic hypertension has also been shown to impair autoregulation: the ability of vessels to change calibre to maintain blood flow as pressure varies. Importantly, BP, IOP, and intracranial pressure affect ocular nutrition.

On short time scales, blinking and eye movement both produce measurable IOP changes. Unfortunately for retinal neurology, IOP elevation reduces the blood supply, and therefore oxygenation, to the nerve fibres and the RGCs, pushing blood into the deeper layers. The severe vascular changes due to unrelenting chronic systemic hypertension outweigh any supposed benefits from increased OPP.

Sleep apnoea adds another factor to the impairment of blood supply and oxygenation, so questions about it should be raised.

At the optic nerve head, a third pressure factor warrants consideration – cerebro-spinal fluid pressure (CSFp) in the subarachnoid space surrounding the optic nerve itself.

Low CSFp is also associated with increased glaucoma risk. Another pressure, translaminar pressure (IOP – CSF pressure), is thought to be responsible for optic disc cupping. The foregoing means that the optic disc, optic nerve head and optic nerve is a complex system with interrelated factors constantly in play. At least with age, none of them seem to be working for the patient’s benefit.

While elevated IOP deforms and compresses the optic nerve, a higher CSFp counters that deformation. In fact, there is less retinal dysfunction with higher CSFps. Unfortunately, CSFp declines by about 3 mm Hg between the 5th and 9th decades of life, largely due to a lower CSF turnover. Although seemingly small, that 3 mm Hg change is sufficient to alter the topography of the optic nerve and is capable of a 4x increase in glaucoma risk.

Age-related tissue stiffness in older eyes (40-50 years of age) is associated with less optic nerve surface deformation but greater RNFL compression, and is believed to be a contributing factor to greater RGC susceptibility to IOP elevation. Furthermore, function is poorer than that predicted by blood flow, possibly due to poorer oxygen extraction and usage.

Exercise is beneficial, and 5 weeks of regular exercise has been shown to be neuroprotective, probably due to improved levels of BDNF (brain-derived neurotrophic factor). Supplementary vitamin B3 (niacin) has been shown to improve energy production during the ageing process.

The complexity of the issues involved, as well as the generally adverse effects of ageing, adds weight to the old adage: “Whatever you do, don’t get old!”

What can be done about dry eye?

Associate Professor Jennifer Craig heads the University of Auckland Department of Ophthalmology’s Ocular Surface Laboratory, in which she pursues her main interests of dry eye (DE) and tear film abnormalities. She was also a member of multiple committees that contributed to the TFOS DEWS II 2017 series of reports.

Her presentation explored the issues surrounding the efficacies of novel approaches to DE treatment. After detailing the revised definition of DE, and aptly describing it as a ‘vicious circle’, she highlighted the DEWS II feature showing the subdivision of DE by aetiological subtype and disease severity. It is divided into four stages, of which the evaporative form remains the most common at 86% of cases.

She described the main aim of any treatment as being the restoration of tear film homeostasis.

Significant contributors to evaporative DE are an increased bacterial load and the role played by Demodex spp. mites in the aetiology of anterior blepharitis, a factor is meibomian gland dysfunction (MGD). In Australia, first line therapy for DE is patient education, in-eye drops, warm compresses, and lid hygiene. Novel treatments include IPL (intense pulsed light) for MGD and Manuka honey for blepharitis.

The prevalence of MGD is known to increase with age and also cause diffuse inflammation of the lid margins, telangiectasia and changes to the MG orifices. Such changes include pouting, obstruction displacement and even a reduction in gland numbers. MGD can be graded from 0 (clear expressed fluid) to 4 (waxy or no expressed meibum). Other features include tear film foaming at the lid margins, tear film debris, lid-margin notching, scarring, and entropion.

IPL is derived from a broadband light source (not a laser) delivering wavelengths between 580 and 1,200 nm. The core technology has been used in the cosmetic industry for hair removal and facial melasma, as well as acne rosacea and ocular rosacea.



"An ongoing issue is the difficulty in explaining just how intense pulsed light benefits dry eye"
Jennifer Craig, associate professor, University of Auckland

Craig commenced IPL studies in 2014 and found positive results initially, including increased lipid layer stability and a decrease in symptoms and their severity. Subsequent studies also showed a decrease in inflammatory markers and an improvement in tear composition. Later studies employed true RCTs with suitable masking. Several studies by others over the same interim period used methods less rigorous than an RCT with masking, leaving their results open to challenge.

An ongoing issue is the difficulty in explaining just how IPL benefits DE. In acne cases, blood is coagulated in superficial vessels, thereby decreasing the presence of inflammatory mediators locally. Those effects mean that the globe itself has to be protected from direct light during therapeutic exposure.

Although IPL generally produced greater responses in those with the worst signs and symptoms, no significant association was shown with aqueous tear production, Staphylococcal lash crusting, or Demodex counts. Benefits proved to be cumulative, but the greatest improvements were noted after four or five treatments.

The next topic Craig tackled was blepharitis treatment using Manuka honey.

Manuka honey is the product of bee activity involving the NZ tea tree and is claimed to have superior anti-bacterial properties. Part of that superiority has been attributed to a unique factor, methylglyoxal (MGO), that can range from 38 to >750 mg/kg of bulk product. It has been shown to be particularly effective against MRSA, Staphlococcus. spp., Pseudomonas aeruginosa, Helicobacter pylori, and the ever-present Escherichia coli. It is known to be a beneficial treatment for leg ulcers, diabetic foot ulcers, and maxillofacial wounds.

In blepharitis, Manuka honey reduces the bacterial load, thereby reducing the presence of bacterial exotoxins that contain lipases known to disrupt the tear film. A UAck formulation of Manuka honey (freeze-dried) complexed with alpha-cyclodextrin (for stability) has been tried successfully in rabbits and subjected to a tolerability trial in healthy humans.

A Manuka honey microemulsion (MHME) has also been compared with tea tree oil in combating Demodex mites. The honey was found to have an efficacy equivalent to 50% tea tree oil. For comparison, 100% tea tree oil is almost immediately effective against the mites, but cannot be tolerated in or around the eye in almost any concentration. The MHME was applied as a cream to the closed eye overnight.

Significantly, uncomplexed Manuka honey exhibited low efficacy against the mites. The MHME trial demonstrated improved ocular surface scores, improved lipid layer characteristics, reduced lid wiper epitheliopathy, a reduced Demodex count, and longer non-invasive break-up times.

Craig’s parting advice was to review critically the claims made in the literature, and to uncover the origin of unknown authors to ascertain the possible existence of any bias or vested interests.

Psychological benefits of contact lenses

Brisbane CL specialist Mr David Foresto opened his presentation on the psychological aspects of CL wear with a brief summary of what visual activity changes can accompany getting older, and what activities can be affected.

Responses included swimming at the beach, taking kids to the beach, watching TV late at night, reading in bed, having children, driving, working and finding a significant other.

His first case report involved a thirty-something female keratoconic expecting her first child, but without a partner. She suffered from anxiety and was concerned about how she would handle a night time emergency with or without her child, given her poor unaided vision.

She was totally dependent (6/60, 6/48) on her CLs during waking hours, but proved to be intolerant of minisclerals during sleep. However, it was noted that sealed minisclerals were totally unsuited to overnight wear and just two nights in such CLs can result in permanent corneal opacities and neovascularisation.

Foresto advised practitioners to consider EW CLs, especially GP CLs, for all high Rx patients, selecting different daytime and nighttime CLs if necessary. Such a step reduces concerns about attending to children at night, responding to emergencies, or falling asleep while watching TV.

To allay fears about MK rates in EW, he showed published MK rates in Australia related to GP CL wear, noting that at one case per 10,000 wearers per annum, perhaps the risk was manageable.

His second case was related to a more recent issue: post-LASIK corneal ectasia. It is an increasingly uncommon issue now that the aetiology is better understood and improved measuring instrumentation more widely available.

The patient’s motivation was simply a serious dislike of spectacles. Unfortunately for Foresto, the patient had already consulted, and been fitted unsuccessfully by, three CL practitioners. CL trialled already included keratoconic and specialised post-surgical designs.

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To complicate matters, front-surface toric CLs were required because of residual cyl issues. No previous CLs proved comfortable enough. Various CL care systems and single-purpose cleaners had also been tried, and at one stage punctal plugs had also been added to the treatment mix.

Despite the previous practitioners’ focus on GP CLs and the patient’s astigmatism, he decided to try toric SiHy SCLs (AirOptix). He was able to provide adequate VA (the astigmatism was irregular and the higher cyl was oblique [X 140]) and all day comfort at relatively low cost, without the need for glasses, further laser surgery, or other ‘enhancements’.

Addressing the so-called Athens protocol, corneal cross-linking (CXL) and PRK combined, he noted that Rx reductions of the order of 1.50 to 2.50 D had been reported in keratoconus, but he was not a supporter of the protocol. One reason is the ability of some of the higher modulus SiHy CLs to mask up to 1.00 to 2.00 D of refractive error.

Addressing patients waking in pain from bullous keratopathy, he saw the choices as therapeutic (Maxidex, Hylo-Forte, etc.) or a bandage CL. He suggested that corneal sensitivity was about 40x that of a tooth root canal. Bandage CLs decreased pain and enhanced both wound healing and corneal re-epithelialisation. For painful corneal conditions, he recommended soft scleral bandage CLs.

Discussing prosthetic and cosmetic CLs, Foresto advised that hand-painted and computer printed SCLs could be created in TDs up to 24 mm. He also advised that CLs beyond those listed in EyeTalk were available, and those listed should be considered as a guide only.

In cases of trabeculectomy bleb ruptures, vitrectomy port ruptures, large lacerations, and some trauma cases, the answer might be a 20 mm TD SiHy or a 24 mm hydrogel bandage SCL.



"He advised practitioners to set realistic goals very early in the fitting cycle to head off problems of unmet expectations"
David Foresto, Brisbane CL

While he claimed that an opportunity existed to enhance quality of life for patients with special CL needs, he advised practitioners to set realistic goals very early in the fitting cycle to head off problems of unmet expectations. When cosmetic colour matching is required, he recommended that the fitter also pay attention to the size of the matching artwork, not just its colour, if a good match is to be achieved.

Other tips based on his experiences include: use high plus in any over-specs if it is advantageous to make the eye look bigger, conversely, high minus to make smaller, use a high cyl X 180 to make the eyes look closer together, employ prismatic power to ‘move’ eyes up or down, and specify an axis of a prism (don’t just stick with 90 or 180) if there is a need to make the eye look rotated for cosmetic benefit.

He also offered some advice on CLs for sport. Tinted CLs, such as yellow or amber, have been shown to enhance recognition speed in some sports, as well as reducing glare. There is also psychological benefit in the ‘belief’ that a competitive edge has been imparted. For astigmatism, consideration should be given to hybrids, sclerals, or minisclerals rather than toric SCLs. He also noted that elite athletes tend to have a high propensity for superstition and also wish to see their fans when competing, so good VA at all distances should be a fitting goal.

He summarised his presentation by suggesting that patients be asked what they have stopped doing, consider an overnight CL option in suitable cases, don’t be blinded by VA absolutely, CL can offer very effective pain relief in some ocular conditions, consider contrast-enhancing tints, and somewhat surprisingly, modern CL options can now help evade the enucleation option in those cases in which a cosmetic CL can hide a disfigured eye. He also expressed some expectation that wavefront-corrected CLs might feature in the future.

The H Barry Collin Research Award Lecture

Melbourne academic and 2019 Collin Medal recipient ProfessorErica Fletcher is deputy head of the University of Melbourne’s Department of Anatomy and Neuroscience, and head of its Visual Neuroscience Laboratory.

Her current positions and research into retinal degenerations, especially age-related macular degeneration (AMD), confirms that she has come a long way since her original graduation as an optometrist. After an MScOptom and PhD at the University of Melbourne, she undertook post-doctoral research at the prestigious Max Planck Institute for Brain Research in Germany, funded by an Australian National Health and Medical Research Council award.

Her work is world class and she has collaborations with some of Australia’s and the world’s best ophthalmological, anatomical, neurological, and optometrical minds.

Her lecture was titled: What’s new in the diagnosis and management of age-related macular degeneration?

Using a particular case report for reference, she detailed the early changes in AMD. She focused on drusen, the characteristic thickenings of Bruch’s membrane, that over the years, along with pigmentary changes, can be followed by either geographic atrophy (GA) or CNV in about one in seven patients.

Predicting progression can be fraught, but it is known that age and genetics are factors. Other factors are lifestyle issues, such as smoking and diet. Patient management includes: assessing risk, monitoring progression, understanding disease mechanism, and the possibility of laser or retinal therapy.

Fletcher, as well as collaborator Professor Robyn Guymer, a CERA ophthalmologist and world authority on AMD, had input into the current classification scheme. It is as follows:

  • Druplets only (<63 microns diamener) – Normal aging changes

  • Medium drusen only (<125 microns) – Early AMD

  • Large drusen &/or pigmentary changes (>125 microns) – Intermediate AMD

  • Neovascular or geographic atrophy – Late AMD

Druplets are the ‘segments’ of the aggregated fruits such as raspberry, blackberry, and mulberry; that terminology is now applied to small drusen. The dimensions are conveniences based on an ophthalmoscopic or OCT imaging of the central retinal vein diameter where it crosses into the optic nerve head – 125 microns.

A druplet has a diameter less than half that measure. For example, < 62.5 microns – 63 microns given the inexactness of such estimations. Drusen are classified as small (druplet, <63), medium (63-125), and large (>125). The risk of AMD progression can be ascertained by a scoring system based on the sum of the scores from each eye. Called the Beckman Classification, it is named after the funder of the international collaboration that created it – Beckman Instruments. The scores are 0 (none), 1, or 2 per eye, where large drusen and/or some pigmentary changes are scored at 1 each.

Should both eyes have large drusen and pigmentary changes, their score is 4 (1,1 and 1,1). The 5-year risk of developing advanced AMD based on that scoring system was presented graphically as: 0 (none), 1 (6%), 2 (12%), 3 (25%), 4 (47%). Using SD-OCT in pre-clinical GA cases, some drusen can be observed to enlarge and then collapse, leading to transmission defects in the choroid. Nascent GA precedes manifest GA by up to three years.

Fletcher then moved onto the related topic of reticular pseudo-drusen (RPD), which she described as an important new risk factor for late AMD.

She advised the use of red-free light in an ophthalmoscope to view them – they appear as small donut-like features. In OCT, they show up as little ‘haystacks’ all over the retina.

Importantly, RPD is in the retina, not under it. It is important because those exhibiting RPD had a 61% chance of developing late AMD, versus 33.4% for those without evidence of RPD. Significantly, GA developed in 22.4% of cases with RPD, whereas only 2.4% of those without RPD advanced to GA.

Fletcher gave the differences between drusen and RPD as follows:


It is believed that genetic mutations can affect waste disposal mechanisms, which can increase the risk of any form of AMD. Anything that can improve disposal is a possible target of therapy development using haematological and immunological approaches.

She then posed the question “Can we treat early signs of AMD?”

Circa 2006, lasers were used to sublimate drusen in an attempt to excise them and head-off AMD/CNV. The result was the opposite; laser treatment hastened the onset of CNV. The lasers used were continuous-wave devices. Local heating and the resulting tissue destruction were blamed for the poorer outcome.

Subsequently, nanosecond, pulsed lasers were tried and proved to be beneficial, as drusen were decreased or eliminated. Additionally, Bruch’s membrane thinned without significant collateral damage. Beneficial effects also followed the use of a nanosecond laser on the RPE, thereby reducing the signs of ageing within the RPE.

Those favourable results lead to the multicentre LEAD clinical trial carried out in Australia and the UK. Subjects received either laser treatment or a matching sham treatment every 6 months for a total of 36 months (Ellex 2RT system). The study measure was progression to advanced AMD. Some 15.4% of the group overall developed late AMD, 13.6%, in the laser group and only slightly more, 17.2%, of the sham group.

However, the presence of RPD made a significant difference. In the drusen cases, the laser treatment gave a 4x reduction in progression rate, whereas the presence of RPD resulted in a 2.5x increased progression, meaning laser therapy of those exhibiting RPD is deleterious. Currently, there is no treatment for RPD cases.

Nanosecond laser therapy is RPE-selective and the retina remains untouched by design. It changes the gene expression in the RPE and repairs it, as well as stimulating the RPE cells to divide producing daughter cells. Lasering also decreases the number of aging genes present, as well as thinning the RPE.

Fletcher’s conclusions were: use the Beckman classification to assess risk of progression in all patients using drusen size as the criterion, identify the presence of RPD and nascent GA, and follow progress in the use of nanosecond laser therapy which is yet to enter mainstream use.

The biggest surprise of the show

Easily the biggest surprise of the show was the exhibition of a prototype Australian-made OCT instrument. Developed by Cylite, their device uses what they call a hyperparallel design (HP-OCT) that produces 1,000 A-scans per frame at up to 300 frames per second, resulting in 300,000 A-scans per second, with an axial resolution of 9.4 microns.

The device started life as an anterior segment instrument, but that has since changed to be more universal, using interchangeable objectives. When fitted with the Anterior Imaging Lens, the device images a large volume, W: 16.6, H: 14, D: 11 mm (17 mm extended), with a resolution of 9.4 microns axially and 33 microns laterally. That means that the anterior segment can be rendered in 3D well beyond corneal dimensions (nominally 11.7 mm).

Alternative lenses are the Retinal Imaging Lens (covering a 8.4 x 8.4 x 8.3 ‘cube’, resolution 9.4 x 19 microns) and High Resolution Imaging Lens (covering a 5.5 x 3.2 x 11 mm ‘block’, resolution 9.4 x 11 microns). The light source is a pulsed superluminescent LED operating at 840 nm with a bandwidth of 32 nm.

A fine-pitched lenslet array forms a grid of up to 1,000 simultaneous ‘beamlets’ that are directed towards the object to be imaged. Up to 300 of those grids, or sets of ‘beamlets’, are scanned per second.

The aim of the technology is to render it almost insensitive to eye and instrument movement, thereby overcoming one of the drawbacks inherent in current technology. It is also claimed to have greatly enhanced frame registration due to multiple, simultaneous surface measurements acting as frame ‘locks’. Dense B-scans and volumetric imaging are employed using a very fine, lateral grid.

The developers are targeting both the clinical community and ophthalmic researchers. Some of the team behind the project have long-term experience in optics and photonics; one is the software engineer behind the interface and computation engine of the internationally-popular Australian Medmont E300 corneal topographer.

 

O=MEGA Clinical Conference gallery










Best stand winner: Proper Goods
Best stand winner: Proper Goods
Best stand winner: Maui Jim
Best stand winner: Maui Jim



 

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