The Cornea and Contact Lens Society of Australia’s 17th International Cornea & Contact Lens Congress delivered an array of entertaining and informative presentations. LEWIS WILLIAMS completes his report on the proceedings.
RGPs, toric SCLs, and the grey areas in between
Mr David Foresto, Brisbane optometrist with a contact lens (CL)-focused specialty practice, was in peak form with an engaging and entertaining presentation. Despite dealing regularly with difficult cases he still accepts the importance of patient satisfaction, although reaching the standard that can be achieved in more straightforward cases is not always possible.
He also reminded his relatively young audience to not be fooled by high sphere-low cyl Rxs when correcting for vertex distance. Commonly, the effective cyl power also changes even when the ‘magic’ 4 D limit is nowhere near being exceeded by the amount of cyl.
Lamenting the low availability of disposable CLs with high cyl Rxs, he stated that some patients do not like their best meridians being blurred by the use of Rxs offering less than a full astigmatic correction, spherical equivalents, or spherical compensations for less than the full cyl.
On the topic of spare spectacles, particularly for keratoconics, he posed the question – best sphere or a full correction for the best meridian?
When compensation is required for the rotational mislocation of a particular toric CL design (clockwise you add, or the more obtuse LARS [left you add, right you subtract]), Foresto suggested trying a different toric CL design rather than chasing mislocation. This is in the hope that little or no compensation will be required with the alternative design.
While not all would agree with him, his suggestion was to avoid making compensations of more than 10 °. Others, including this writer, would be prepared to consider 15 to 20 ° compensation but the fact remains that with such a large change pending, the next CL ordered is a different entity to the original, and predicting its on-eye behaviour is fraught.
He also pointed out that when prescribing prism-ballast or periballast CLs, vertical prism is introduced which can lead to a vertical imbalance. He mentioned that the Johnson & Johnson toric SCL is not ballasted. Rather, it is a variation of the double slab-off, dynamic stabilisation concept.
In his experience with keratoconics, Foresto has also identified a shift in CL practice brought about by the wider adoption of corneal cross linking (CXL), especially the adoption of the so-called Athens Procedure (CXL and either phototherapeutic keratectomy [PTK] or photorefractive keratectomy [PRK] in the same treatment session). The number of cases with aided vision worse than 6/12 has decreased, as have the number of cases exhibiting large Rxs. Regardless, he still believes that CLs are better than laser procedures overall.
Supporting that belief is his rejection of the description of CXL (Athens procedure or otherwise) as being a ‘stabilising’ procedure, because CXL actually results in a progressive flattening of Ks over time. In his experience, that flattening can be extreme (4 to 9 D). Furthermore, corneal topography is altered significantly by CXL and can appear to be Ortho-K-like. Because of this, Foresto stated that CXL was not a refractive procedure. He reserved CXL referral to only those who were CL intolerant or for whom CL or spectacle vision was inadequate after all avenues were explored.
If a cornea needs to be regularised to improve aided vision, he saw the choice as being between laser or a CL (rigid or soft). Even daily disposable (DD) SCLs can mask up to 2 D of corneal astigmatism. He reported that the Kerasoft specialty keratoconic SCL was always a useful consideration, as well as the combination of a DD SCL worn under spectacles.
On the topic of toric SCLs versus rigid gas permeable (GP) CLs, he noted that in cases of residual astigmatism, any posterior toricity or irregularity is difficult to deal with regardless of CL type because the posterior cornea is inaccessible optically.
As with many types of CLs fittings, the management of patient expectations is of paramount importance, especially in challenging cases in which 6/6 or better vision is difficult, if not impossible, to achieve. Obviously, lower expectations are easier to meet.
An approach he uses early in his interactions with difficult cases includes, ‘If I can get you five (or slightly better) out of 10 vision, will you be happy?’. Excessive expectations either needs to be lowered by education, or the patient referred to another practitioner who might be able to meet their desires. Unfortunately for Foresto, he is often the ‘end of the line’ and left with an insoluble problem.
Vision stability is dependent on CL rotation, CL movement, CL surface dryness, and CL dehydration (that is water content inside the CL, not just its surfaces). Although relatively uncommon, there were still applications for toric periphery/spherical optic zone, bi and quad asymmetric periphery CLs, and true bitoric CLs.
In cases of early bilateral keratoconus, Foresto does consider CXL early, on the basis that 6/6 vision can often be achieved with CLs, albeit CL with changing Rxs to track CXL-induced topography changes. When optical path difference (OPD) aberrations are corrected (in the context of wave-front-guided aberration corrections) he reported reductions of 32% in coma, 6% in trefoil, and 60% in spherical aberrations.
Myopia – the evergreen topic
Dr Kate Gifford and Dr Paul Gifford shared the stage for a presentation on some of the finer points of myopia, myopia progression, and axial length (AL), as well as treatment options.
Seemingly unrelated elements, such as pupil size, have been shown to be a factor. A large pupil affects the magnitude of the eye’s peripheral refraction, which has been shown to be a significant factor in myopia development and progression. Pupil size can also impact myopia interventions. For example, it can alter any induced peripheral refraction, thereby affecting the treatment’s efficacy. Similarly, a CL’s treatment zone diameter can affect peripheral refraction, as can CL decentration or anatomical pupil decentration.
Pupil diameter also affects paraxial aberrations. The loss of beneficial peripheral refraction effects can be marked when pupils are >5 mm in diameter. In addition to atropine studies undertaken in East Asia, there is now increasing acceptance of a combination of MF CLs and atropine treatment. Other studies have shown that hyperopic peripheral refraction (HPR) leads to choroidal thinning, which results in a small increase in apparent axial length and therefore myopia. However, the combination of HPR and atropine showed no change in choroidal thickness.
Kate Gifford spoke on the topic of accommodation, efficacy of myopia control, and visual discomfort. She found that when the patient’s accommodative lag was >1 D, a factor in 48% of her study group, CL discomfort (CLD) was experienced, but not dry eye. When the accommodative response was enhanced, so too was the efficacy of any concurrent myopia treatment. When MF CLs are used as a part of myopia treatment, the peripheral myopic defocus they induce is desirable. However, if a centre-distance MF design is deployed at near, hyperopic defocus results can be neutral or even disadvantageous.
The same can result from the off-axis optics, including centrally, provided by a CL that routinely decentres. Generally, she found that a decreased accommodative response also resulted in a decreased anti-myopia effect. Accommodative lag was also found to decrease when aspheric CL designs were used. Interestingly, the CooperVision MiSight anti-myopia CL has been found to have little effect on accommodative lag, whereas Ortho-K decreases (by about 0.75 D) accommodative lag, as does MF CLs (by about 1.25 D). Ortho-K is often better in cases exhibiting a lower baseline accommodative amplitude.
The ideal myopia control CL was described as one that increased positive spherical aberration and relative peripheral myopia, while decreaseing esophoria and accommodative lag. Such a CL would probably work best when used in combination with low-dose atropine. Possible CLs that can assist myopia control were given as: CooperVision MiSight (+2 D dual-focus zones), CooperVision centre-distance MF, Visioneering Natural Vue (MF, single high add), mark’ennovy MYLO (EDOF), Menicon Bloom, and virtually any Ortho-K system.
Team Gifford is looking forward to a time when CL prescribing and CL design will be based on the accommodation status of the wearer and whole-of-eye optical modelling will show what is really going on with and without treatments.
Managing the ocular surface
Melbourne optometrist Mr Jason Teh, whose practice has a dry eye (DE) and ocular surface disease focus, arrived at the lectern wearing sealed goggles that promptly fogged (Blephasteam), a helmet labelled Thirst Aid to which was attached pair of plumbed beer cans (implying hydration), and a raincoat.
He is part of the Melbourne-based Dry Eye Group of practices, which offer DE care services and screening. Unsurprising given his costume, Teh stated that Blephasteam goggles were still relevant. He described DE care as being 50% about communicating with the patient and rejected claims that clinical ‘toys’ are required to pursue DE patients. However, the usual problem of patient compliance remains.
Quoting DEWS II figures, he estimated DE prevalence as being between 5% and 30% depending on sex, ethnicity, and geography, especially in the over 50 age group. Up to 70% of those affected have meibomian gland dysfunction (MGD). Other data suggests that aqueous deficiency accounts for about 20% of DE cases, 30% to 68% have MGD, and about 10% have a mixed condition.
The affected group are also more likely to have glaucoma, myopia, and age-related macular degeneration (AMD). The age factor, as well as diet and lifestyle, are probably confounding factors. Aetiology and associations might not be as clear-cut as the data above implies.
Teh described the DE patient group broadly as being undiagnosed, uneducated, and untreated. MGD can take 18 months or longer to resolve even with ongoing care. Denial of the condition is not unknown and quality of life is known to be affected. DE treatment has elements of the ‘Gift of Healing’ intermingled with ongoing care, but compliance and appropriate treatment are obviously also key.
His group check for MGD in all patients, and they have found the biggest group fall into the 25 to 40 years age group. Lid wipes are prescribed for use each morning and evening. Asymptomatic MGD can be expected to eventually move to symptomatic MGD, and therefore cannot be ignored. While not essential, complex instruments like OCTs can be used to measure tear prism height to differentiate aqueous deficiency from other variants. A transilluminator applied to the lower eye lid can aid an assessment of the Meibomian glands in vivo. The group’s preferred questionnaire is the DEQ5.
The Blephasteam goggles were described as the cheapest and easiest entry into DE treatment. The 3-in-one Oculus Keratograph 5M (topographer, keratometer, and colour camera) represents the other end of DE assessment. Desirable tests include tear film break-up time (TF BUT), tear osmolality, ocular surface vital stains, and MMP-9 assays.
In his opinion, invasive TF BUT techniques involving the instillation of sodium fluorescein should be the first dropped from routine use. He also suggested that redundant conjunctival folds that lie parallel to the lower lid margin should be noted as a suspicious sign.
Teh stated that steroid therapy does not solve all problems, IOP management can be an issue, and Manuka honey does have a therapeutic role. A preservative-free non-steroidal anti-inflammatory drug can also be useful.
Using some case studies as a vehicle for further discussion, Teh noted that chemotherapy, especially for breast cancer, can have ocular manifestations or exacerbate existing surface problems. Systemic problems, such as Sjögren’s syndrome, have several manifestations.
In cases of peripheral nerve damage, including diabetes, decreased tear production can be experienced. However, the more general nature of the condition necessitates the involvement of other health professionals. Irregular or inadequate sleep is also detrimental.
In his experience, Teh often finds that other professionals have ignored important aspects of care. His advice was to spend time with patients.
On the topic of Omega-3 fatty acid supplementation, he referred to a Cochrane Review that found if the patient’s dietary intake was adequate there is no justification for supplementation. In some cases, a reduction in Omega-6 intake is more appropriate, as excessive intake is known to be pro-inflammatory.
As to treatments, the complex LipiFlow system has evidence supporting its use, and debridement with regular forceps gland expression is also effective. Blephasteam can be used daily and is flexible enough to allow most exercise routines to be carried out while the treatment is being applied.
The possibilities of presbyopia
Brisbane-based optometrist Mr David Stephensen, who shares a focus on specialty CLs with Foresto, chose the thorny topic of presbyopia correction.
He estimates that when a multifocal CL (MF CL) is fitted and there is adequate adaptation, as well as an element of ‘faith’, success can be achieved. In his hands, there is a high success rate with presbyopic CL options, so long as the manufacturer’s fitting guide and protocols are closely followed.
He finds that six out of 10 patients will meet with adequate success. However, he did admit that rarely did CL vision better what is provided by optimum presbyopic spectacles. He went further and advised his audience to not warn or explain the issues to the prospective presbyopic CL wearer. Rather, insert the CLs and go from there. Of course, if the patient’s expectations are excessively high, success is unlikely. Realistic expectations, which probably include 6/Happy rather than 6/6 or 6/4.5, are conducive to success.
Common CL performance issues, such as visual acuity, contrast sensitivity, and comfort, are not predictors of success. It is worth remembering that spectacles also have limitations, and Stephensen raised the issues arising from the use of multi-monitor computer configurations and progressive power spectacles or, worse, bifocals or reading glasses. Such work environments are better catered for with CLs because they have fewer field-of-view limitations.
Perhaps surprising some in the audience, he described MF CLs as a non-scientific concept that works adequately for most wearers. Remember, CL practice has an element of art as well. Overall, he views MF CLs as a suitable first-line treatment of presbyopia that in many ways are better than spectacles.
Rapid Fire academic papers session
Several established young CL researchers delivered presentations on their special areas of interest. Dr Nicole Carnt, a UNSW Scientia Fellow and Senior Lecturer in SOVS, reinforced the message that tap water has no role in CL care due to the risk of infection, most especially Acanthamoeba keratitis (AK) which is initially misdiagnosed in about 50% of all cases.
While rare, the condition is devastating, the outcomes almost universally poor, and in about 70% of cases patients suffer the disease for more than 12 months. In a UK-based study that Carnt was involved in, poor CL hygiene was responsible for more that 35% of cases, showering while wearing CLs a further 32%, using the OxiPol CL disinfectant (not available in Australia), deficient hand hygiene 19%, and the use of Group IV SCLs about 4%.
Prompted by her own misfortune with an AK infection, one UK CL wearer designed a ‘No Tap Water’ icon and later the British Contact Lens Association adopted the icon as a stick-on label that practitioners could apply to their CL deliveries. In a study of 200 wearers, a significant improvement in wearer behaviour accompanied the use of the sticker. The CCLSA is pursuing a similar strategy.
Associate Professor Stephen Vincent from QUT’s School of Optometry and Vision Science undertook research on the decentration of scleral CLs. The issue is known to affect wearer comfort, ocular health, and vision quality. The latter is particularly affected when the CL has a wavefront-guided front surface design, because any decentration negates aspects of the complex design’s aims.
Factors affecting decentration range from the simple (gravity and the shape of the anterior eye) to the more dynamic (the lids and blinking behaviour). Methods range from simple CL marking to the more complex image analysis of the actual CL on the eye. Vincent used an OCT for this, although he admitted that the method had little relevance to routine private practice. Alternatively, a videokeratoscope/topographer can be used in either standard tangential power map or normalised tangential power map mode. A Medmont E300 instrument provided good agreement between the standard tangential power map and other methods.
He has found the increased decentration can often be traced to an increased horizontal asymmetry of the anterior eye. A CL fitted with or exhibiting apical clearance can increase vertical decentration. A combination of a more anterior CL centre of gravity and apical clearance is likely to enhance downward decentration
Long-time clinical CL researcher Mr Daniel Tilia is undertaking a PhD at SOVS, UNSW into the role of binocular vision disorders (BVDs) in CL wearer dissatisfaction.
While about 60% of dissatisfaction can be traced to discomfort and a further 15% to vision problems, especially in toric CLs, the actual contribution attributable to BVDs remains unknown. On average, myopes are known to have reduced amplitudes of accommodation, increased accommodative lags, and less
Using various questionnaire instruments, he has traced about 22.4% of wearer dissatisfaction to BVDs. The Ocular Surface Disease Index (OSDI) reveals significant differences between BVD and discomfort, strongly suggesting that BVD is a separate entity that has probably confounded previous investigations of ‘dissatisfaction’.
Dr Maria Markoulli a senior lecturer in SOVS, UNSW, the recipient of several teaching awards, and deputy editor of the Australian journal Clinical and Experimental Optometry, spoke about MMP-9 and scleral CL wear.
She defined a scleral CL as one whose TD is 16 mm or greater. Despite the increasing popularity of scleral CLs, their effects on the ocular surface are not well understood and her research is hoping to provide some further answers. MMPs (matrix metalloproteinases) are a group of enzymes that collectively act in the extracellular environment that degrade matrix and non-matrix proteins in the contexts of tissue development, tissue repair/wound healing, tissue remodelling, and morphogenesis.
MMPs 2 and 9 specifically are present in the tears and the cornea. They are involved in wound healing and ocular surface diseases including DE and KC. They are involved in the stroma’s basement membrane anchoring fibrils made of Type VII collagen. The latter is a known substrate of MMP. It is thought that excessive MMP activity can play a role in epithelial, stromal, and endothelial dystrophies.
It now appears that the balance between MMP-9 and TIMP-1 (tissue inhibitor of metalloproteinases or TIMP metallopeptidase inhibitor 1, a glycoprotein) has a role in corneal homeostasis, and imbalances have been implicated in pterygium, corneal ulcers, corneal erosions, and sequelae of CL EW. TIMPs are also capable of promoting proliferation of a wide range of cell types, as well as having an anti-apoptotic function.
Using Visionary-Optics Jupiter scleral CLs fabricated in Boston XO GP material for a five-hour wearing trial, no significant difference in tear film MMP-9 was found, but an increased range of the data was noted. Conversely, while again no significant difference in TIMP-1 was found, its data range decreased.
Markoulli concluded that there was no general trend of an increase in MMP-9 in scleral CL wear, but there were differences in some study subjects. She concluded that a larger study
was required before further conclusions can be drawn.
Dr Laura Downie, senior lecturer in the Department of Optometry and Vision Sciences, University of Melbourne, gave a presentation on inflammatory biomarkers in the tear film and their possible association with CL wearer discomfort. The latter is known to be a major trigger of the discontinuation of CL wear, but the cause is also believed to be multifactorial. Inflammation is a normal pathological process to physical, chemical, or biological injury that results in the signs of rubor, dolor, tumor, calor, and functio laesa.
Often sub-clinical mediators are involved in the mobilisation of cellular processes and the upregulation of relevant pathways. Biomarkers originating from dendritic cells, which are responsible for initiating immune responses, are part of a system that is dynamic but non-invasive. Laser confocal microscopy is one way of visualising the eye’s response to a threat.
Although SCL wear is capable of inducing an inflammatory response, it is small and sub-clinical. Regardless, an increase in corneal dendritic cell density can be detected in as little as two hours, but the increase is a function of CL type and the care system that has been used to maintain it. An increase in lid wiper dendritic cell density has also been found.
Tear film biomarkers include signalling lipid mediators derived from arachidonic acid that control cell proliferation, apoptosis, metabolism, and migration. One mediator can be a metabolic by-product of Omega-6 metabolism. Another biomarker can be cytokine activity in both symptomatic and asymptomatic cases. The protein interleukin-17A (IL17A) has also been shown to be upregulated in patients complaining of CL discomfort.
Anti-inflammatory interventions, such as the application of cyclosporin, have been shown to decrease discomfort and increase wearing time. The use of the Omega-3 supplements EPA 900 and DHA 600 for 12 weeks has also demonstrated decreases in wearer discomfort suggesting anti-inflammatory therapy might be a useful intervention