How we interact, interpret and see our environment determines who we are. This is the foundation on which developmental or behavioural optometrists operate. Vision therapy practitioners often see the refractive behaviour of an individual before it is measured because there is a strong relationship between vision and personality. For instance, people who are nearsighted are more likely to display certain personality patterns and mannerisms that are different from those who are not.

It is important to understand that a significant number of vision problems, including myopia, are the result of mal-adaptations to the stresses in our environment or improperly learned patterns that we develop in life. We are not born with poor vision. There are, of course, people who are born with congenital cataracts or distinctive visual dysfunctions but they represent only a small percentage of the population. Most people are born without vision issues. Vision is a process that develops and is learned.

So, how do people become myopic and how do they relate to their world? Everyone, admittedly, is spending more time indoors, reading and working on computers and digital devices. The increased demands in our near-centred culture cause strain in our visual system as we adapt to meet the near visual stress, often at the expense of clear distance vision. Myopia development begins at near because it is a symptom of a near-point visual dysfunction.

When nearsighted people are exposed to external pressure, their perception is always pointed internally. They respond, either by constricting their physical world closer to them, or by withdrawing from their environment for security in a flight response — without actually running away — when things get too challenging. The internal responses they demonstrate are often charged with emotion that quickly becomes their customary pattern. They are in survival mode and have developed this way of seeing to protect themselves. They are frequently introverted, socially insecure and reserved. More often than not, their behaviour is skewed toward detail and tensed eye and body musculature.

The eye problems nearsighted people present can provide insights into greater internal imbalances and skewed patterns of reality. The personality of nearsightedness transfers to how people think, how they speak, the way they see themselves, the way they interact with others, and the way they adjust their posture.

These people tend to be rational thinkers, which helps them to make sense of the modern, logic-driven society they live in. Being logical allows them to be pragmatic and more focused without becoming emotional. This allows an assigned job or task to be meticulously completed, which may facilitate job advancement or a financial reward. Clinical research papers have shown a strong association between nearsightedness and analytical and intellectual activities and high intelligence, which these individuals frequently have.

It is possible to identify the anomalous near clinical findings that drive myopia development with a functional vision assessment by a developmental or behavioural optometrist. The solution is not to prescribe compensatory lenses for distance for full-time wear, especially at near, but, rather, appropriate low plus-powered lenses at near as determined by stress retinoscopy for all near work. Another method used to intervene, prevent or reduce myopia progression is through a vision therapy program. Myopia is mirrored in the mind, in the emotions, and in the body as a whole. Nothing can be done to change myopic perceptions without working the entire body as one unit. Here, an individual at risk for developing or showing early signs of myopia is given activities to change the neurology that will bring stability and support to the visual system at near.

Other therapeutic options include low-powered BI or BD prisms, bifocals, multifocal contact lenses, orthokeratology lenses and low-dose atropine. Researchers have also recommended turning off digital devices and going outdoors. There is a very strong correlation between myopia and overusing electronic devices while not being outdoors enough. Some studies suggest that myopia might be linked to lower levels of vitamin D, the sunshine vitamin, but it is unclear why spending time outdoors benefits myopes; studies cannot prove if the primary reason is UV radiation, vitamin D concentrations, light intensity or other factors. People with myopia should also eat a diet that includes Omega-3 fatty acids, lutein, zeaxanthin, vitamin A, vitamin C and vitamin E that are found in a variety of foods.

You don’t want to be shortsighted, do you? Help your patients with nearsighted behaviours to refocus, change their perceptions and expand outward into the world. You can learn more this summer in Niagara Falls, ON at the Canadian Optometrists in Vision Therapy and Rehabilitation’s Myopia Conference, which will feature classical and behavioural international optometry lecturers. Visit www.visiontherapycanada.com for further information.

This is the second of two developmental optometry stories. The first story appeared in the March/April issue of Envision: seeing beyond magazine.

By Shirley Ha HBSc, OD, FCOVD

Developmental, aka neuro, neuro-developmental or behavioural optometry, is exploding in Canada, thanks to the passion, motivation and energy of the ALL-IN campaign, launched by the Canadian Optometrists in Vision Therapy and Rehabilitation (COVTR). These optometrists provide life-transforming vision therapy and rehabilitation services to their patients via a specialized area of optometric care that works with the eye-brain-body connection.

While a majority of eyecare professionals deal with the health of the eyes — or “hardware” — and provide compensatory prescriptions to their patients so they can see clearly, developmental optometrists describe vision, or the “software”, as a dynamic process that involves more than eyesight. They recognize that vision, as the dominant sense, is pervasive in all aspects of life. It is learned and developed through interaction with the environment and through life experiences. Vision is the entire process that gathers, assembles and integrates sensory and motor information, to and from the brain, body and environment, with what is seen through the eyes. This provides meaning in order to direct accurate, comfortable and efficient motor movements or actions.

Good visual acquisition skills (how we get information into the brain) and good processing skills (how we interpret, use and project visual information) influence human development and provide a foundation for new learning. A breakdown in eye teaming, eye movement and peripheral awareness can happen over time, as a result of visual stress, or following a head injury such as a concussion. Such breakdowns are closely linked to a reduction in depth perception and balance, inefficient processing and uncomfortable vision. When undiagnosed, vision problems can become barriers to success in academics, sports and life. In the words of the late Dr. John W. Streff of Lancaster, OH, a founding father of the developmental optometry community, “When vision is good, it leads; when it is poor, it interferes.”

Developmental optometrists use powerful tools such as lenses, prisms, tints/filters and vision training to rewire the “programming” or neural pathways and help guide vision development, rehabilitate a compromised visual system and improve visual performance.

COVTR is a three-year-old non-profit organization dedicated to enhancing optometric education and public awareness of vision therapy and rehabilitation (VTR) to improve the lives of Canadians (www.visiontherapycanada.com). It has grown from a group of seven optometrists in a vision therapy study group in 2014 to a national organization representing over 300 members, including optometrists, vision therapists and students.

This rapid growth has resulted in many sold-out continuing education events across Canada. An unprecedented eight Canadian optometrists completed post-graduate training in VTR and obtained fellowships from the College of Optometrists in Vision Development (COVD) in Jacksonville, FL in 2017. The organization is propelling VTR to the forefront of vision care nationwide across Canada and is in the midst of a movement to show that VTR success is not limited to one community or practice – it is everywhere.

Thousands of Canadians are now enrolled as patients in vision therapy and rehabilitation programs across the country. COVTR’s goal is to ensure that all Canadians are informed about VTR and given the opportunity to participate in these life-changing services. The organization’s members are remediating patients with binocular vision dysfunctions, such as convergence insufficiency, and children with learning-related vision problems and academic delays. They offer effective, non-surgical management for patients with eye turns (strabismus) and lazy eyes (amblyopia), and novel ways to alleviate concussion and head injury symptoms, such as dizziness, double vision and light sensitivity, for those with acquired and/or traumatic brain injuries. In addition, athletes who want to develop their visual abilities for optimum results are benefitting from sports vision-enhancement activities.

At COVTR’s 2nd Annual General Meeting and Conference in August, 2017, commemorating a historic 75 years of vision therapy in Montreal, the inaugural class of 2017, made up of 37 vision therapists and two optometrists, graduated from Canada’s first-ever Practical Vision Therapist Accreditation Program (PVTAP). It is an 18-month program, developed in conjunction with a licencing agreement with the Australasian College of Behavioural Optometrists (ACBO), for optometrists and their vision therapists. The goal is to facilitate the successful integration of VTR into their practices by providing participants with the relevant theory and understanding of the development of vision problems and strong practical experience for gold-standard, office-based therapy delivery and management for their patients.

COVTR is making waves, not only in Canada but around the world. And this year, for the first time, Canada will be represented at the International Congress of Behavioural Optometrists (ICBO) event in Sydney, Australia. The landscape of VTR in Canada looks very bright for optometrists who are ALL IN and want to increase their knowledge base to help their patients. Similarly, the outlook is positive for their patients, giving them hope of controlling their visual symptoms and retraining their brains to use their visual systems more effectively and efficiently.

By Shirley Ha

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This is the first of two developmental optometry stories. The second story will run in an upcoming issue of Envision: seeing beyond magazine.

By Shirley Ha, HBSc., O.D., FCOVD

Not all dry eye problems, including those related to wearing contact lenses, are the same. Typically, dry eye patients, both contact lens wearers and non-wearers, report symptoms of dryness and have signs of inadequate tear volume, decreased tear breakup time (TBUT) and corneal staining that support the dry eye diagnosis. However, there are some dry eye patients and contact lens wearers without dry eye who have normal, objective test results but continue to complain of discomfort that mimics the symptoms of dryness and grittiness. Notwithstanding the routine assessment and management of aqueous dry eye and Meibomian gland dysfunction (MGD) that disrupts tear film support, lid wiper epitheliopathy (LWE) is often an overlooked condition, one that is characterized by worldrenowned dry eye researcher Dr. Donald Korb of Boston, MA as the distinctive feature for symptoms of dry eye¹.

The lid wiper area lies behind the row of Meibomian glands on the upper lid margin. Akin to a windshield wiper blade, it moves up and down across the bulbar conjunctiva onto the corneal surface about 12,000 times a day to clear the eye of debris and replenish the pre-corneal tear film layer that protects the ocular surface from mechanical stresses during a blink.

In patients with symptoms of dry eye, decreased lubricity or increased coefficient of friction between the lid wipers and the lens surface occurs and the lid wiper surface becomes compromised. The constant friction causes a change to the epithelium of the inner-upper lid margin. Instead of a wiper blade that glides smoothly without leaving “streaks” in the tear film, clinically shown as decreased TBUT, the irregular lid wiper area now has uneven pressure over the contact lens surface, increasing its sensitivity and patient discomfort.

The causes of LWE are many and can include pre-existing dry eye conditions, secondary, but not limited to exposure keratopathy, age, cosmetic lid surgery, lagophthalmos, incomplete blinking and environmental factors. With any new contact lens fits or refits, the lid wiper area should be scrutinized for evidence of LWE, in addition to other screening tests. This should be repeated at all regular follow-ups thereafter.

Clinically, LWE is detectable with topically applied fluorescein or lissamine green or rose bengal dyes. By gently lifting and everting the upper lid, the lid wiper area can be assessed and classified for width, length and shape of the staining.

The increase in epithelial permeability in this region must be differentiated from the same dye uptake that occurs in the Line of Marx (LOM). While LWE is caused by repeated irritation between the lid wiper surface and the front surface of the lens, the LOM is a “normal” thin band of accumulated, superficial, conjunctival epithelial staining that lies directly behind the mucocutaneous junction.

LWE patients demand lubricious contact lenses that can reduce the insult to, and protect the lid wiper area and the ocular surface. Sometimes it is best to discontinue wear for a while if there has been chronic irritation of the lid wiper area. Lenses with higher surface wettability, such as the Alcon’s DAILIES TOTAL1® water-gradient contact lenses, with better oxygen permeability (SiHy material) and lower modulus may help reduce the LWE mechanical friction, as can Type I, II – lower ionicity lenses that minimize protein buildup. Also, patient compliance in the cleaning and lens replacement regime, with emphasis on rubbing and rinsing immediately after CL removal and timely replacement, is necessary to ensure that the lenses are clean and fresh for everyday wear.

Recommend contact lens solutions that remove lipids and proteins effectively while providing a more wettable lens surface to protect it from lipid and protein deposition. Sometimes the additional soak prior to lens insertion can offer improved comfort by further enhancing the beginning wettability of the lens. For incomplete blinkers, blinking exercises can be prescribed several times a day. The lids should “kiss” each other on each blink in order to modify and develop better blink habits and to forcibly express the Meibomian gland for better tear film stability. Blink training also has a very important biofeedback mechanism to prevent forced blinking, which may be very negative. By placing the index fingers on the lid margin during a blink, there should be no pulling sensation if blinking correctly.

The posterior margin of the eyelid is an important but under-assessed structure when it comes to ocular surface diseases and non-specific contact lens dropouts. LWE with staining may be an early indicator of dry eye disease and should be considered and evaluated, even when contact lens patients are asymptomatic and/or if diagnostic dry eye testing is normal. For contact lens providers, restoring the lid surface to some normalcy can increase contact lens performance and comfort for patients and decrease idiopathic contact lens dropout.

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1. KORB DR, HERMAN JP, BLACKIE CA, et al. “Prevalence of Lid Wiper Epitheliopathy in Subjects with Dry Eye Signs and Symptoms”, Cornea, vol. 29, April 2010, p. 377-83.

By Shirley Ha, HBSc, OD, FCOVD

It is a little-known fact Sir Arthur Conan Doyle was an ophthalmologist before he gave Sherlock Holmes to the world. Doyle created a hero who was very adept at gathering evidence and using deductive reasoning and science to solve his cases. Like the greatest investigator in detective fiction history, eyecare professionals (ECPs) are detectives when caring for their patients’ eye and vision care needs, from organizing clinical data to diagnosing and managing conditions ranging from retinal diseases to contact lens-related dry eye symptoms.

Not all patients can wear contact lenses and not all contact lens wearers can wear them successfully. In fact, nearly 50 per cent of contact lens wearers drop out, citing discomfort as their primary reason¹. According to Nichols et al., as many as 52 per cent of wearers encounter dry eye symptoms². At its recent symposium, the International Society for Contact Lens Research (ISCLR) proposed meibomian gland dysfunction (MGD) – both obvious and non-obvious – and lid wiper epitheliopathy (LWE) as major contributors to contact lens discomfort and discontinuance. Nevertheless, ECPs are resolved that a good diagnostic workup and early detection and management can build up wearing time and increase the biocompatibility between the contact lenses and the ocular environment.

In general, dry eye is a complex condition and diagnosing it is not as elementary as it might seem. Some patients have clinical signs without symptoms while others are symptomatic and have few or no clinical signs. Here are some key steps to follow when contact lens patients present with dry eye symptoms.

Background Check

A detailed patient history is crucial to determine whether an existing, concomitant dry eye condition that is not related to contact lens wear might be contributing to the patient’s discomfort.

The causes of dry eyes are numerous. They may include, but are not limited to, systemic diseases (acne rosacea, rheumatoid arthritis, Sjogren’s syndrome), medications (diuretics, antihistamines, oral contraceptives), the environment (humidity, sun, wind), age/gender (hormonal changes), poor diet and social habits (alcohol, smoking). Beginning or resuming contact lens wear without addressing these causative factors will exacerbate dry eye irritation and symptoms.

Formal Interviews

Use standardized dry eye questionnaires such as the Ocular Surface Disease Index (OSDI), the McMonnies questionnaire or the Standard Patient Evaluation of Eye Dryness (SPEED) to assess the severity of the symptoms when the lenses are in the eyes, taking into account LWE and MGD symptoms of itchiness and morning discharge, any reduction in the frequency of wearing the lenses and the impact on the patient’s daily life.

The Usual Suspects

Look for evidence of MGD and evert every upper palpebral conjunctiva for evidence of LWE before starting contact lens wear and during all progress checks.

Also rule out other conditions that are predictive of or can contribute to dry eye problems, such as exposure keratitis, corneal dystrophies, allergic conjunctivitis, Bitot’s spots, conjunctival parallel folds, abnormal blink pattern and rate, including allergic responses to the contact lens material, the lens care solution or lens surface biofilm.

Other contributors to dry eye problems include improper lens fit, lens design and material, poor hygiene, not adhering to the wearing schedule and non-compliance with the cleaning regime.

The Forensic Tools

All contact lenses disrupt the pre-corneal tear film and can become adverse ocular irritants, and any unstable or abnormal pre-corneal tear film can make contact lens wearing intolerable, leading to drop out.

In some patients, both the quality and quantity of this tear layer are crucial in determining whether contact lens wear will be successful or if it should be avoided altogether. Auxiliary testing procedures such as the Schirmer and the phenol red thread test measure the quantity/volume of tears produced. The quality of the tear film is assessed by observing the lipid layer, the tear break-up time (TBUT), and the amount of debris in the tear meniscus and its speed of travel.

Staining tests or strips such as sodium fluorescein, rose bengal or lissamine green provide information about the integrity of the pre-corneal, corneal and conjunctival surfaces. For moderate-to-severe dry-eye conditions, further workup such as tear film osmolarity, lysozyme activity assay and tear glucose tests can also be considered.

The Road to Comfort

Eliminating contact lens-related dry eye symptoms poses many challenges. Every contact lens wearer will encounter dry eye symptoms at some point in their wearing lifetime. This is because patients are unique individuals with constantly changing ocular surfaces, depending on their work habits, environment, intrinsic issues (such as hormones, stress and lack of sleep), varying blink rates and tear chemistry. It is important to keep abreast of new research to better understand the dry eye disease and recognize the signs and symptoms of dry eyes in wearers in order to diagnose them accurately before they express contact lens intolerance and drop out.

1. RUMPAKIS, J. “New Data on Contact Lens Dropouts: An International Perspective”, Review of Optometry, vol. 147, January 2010, p. 37-42
2. NICHOLS J.J., ZIEGLER C., MITCHELL G.L., NICHOLS K.K. “Self-Reported Dry Eye Disease across Refractive of Modalities, Investigative Ophthalmology & Visual Science, vol. 46, June 2005, p. 1911-14.

By Shirley Ha, HBSc, OD, FCOVD

Therapeutic bandage contact lenses (BCLs) have been around since the 1970s, yet emergency room doctors and nurses are still patching eyes with antibiotic ointment for non-penetrating injuries. When used appropriately, BCLs are safe and effective, and should be the first treatment option, rather than the last, for many corneal injuries, ocular surface diseases/disorders and post-operative conditions. BCLs typically do not have prescriptions in them and are available in hydrogels, silicone hydrogels, scleral lenses and collagen shields.

The main function of BCLs is to protect the compromised corneal surface from external hazards while the cornea is healing from injuries such as corneal laceration, chemical burns and epithelial defect due to mechanical trauma; from ocular surface diseases such as recurrent corneal erosion (RCE), Sjogren’s syndrome and filamentary keratopathy; and from surgeries such as pterygium removal, penetrating keratoplasty and keratectomies, including photo refractive keratectomy and biopsies.

Patients requiring BCLs have symptoms of redness, tearing, photophobia and blurred vision and they experience pain, from mild to excruciating. BCLs are part of the armamentarium, together with topical anaesthetics and topical non-steroidal anti-inflammatory drugs (NSAIDs); they are used to help manage and control pain by shielding the loose and regenerating epithelium from the constant rubbing action of the eyelids during blink, such as in RCE cases and in painful bullous keratopathy when blisters at the epithelium rupture.

For challenging cases where BCLs have failed, such as in chemical burns, neurotrophic corneas, persistent epithelial defects and Stevens-Johnson Syndrome, some eye surgeons are using the FDA-approved cryopreserved amniotic membrane products, AmnioGraft^® and PROKERA^® biologic corneal bandage that can be inserted in the clinic.  These tissue products are processed by  Bio-Tissue^® and are indicated for corneal and conjunctival healing. AmnioGraft^® is currently being distributed by Labtician Ophthalmics in Canada. PROKERA® is expected to be approved by Health Canada some time in 2015.

ECPs are choosing extended wear (EW) silicone hydrogels for their BCLs because of their high oxygen permeability, flexibility, availability, ease of fit and comfort. Their disadvantages are their lipophilic properties, decreased wettability and fixed lens diameter. For safeguarding near and/or beyond the limbus, larger-diameter scleral lenses or larger-diameter bandage soft contact lenses (BSCLs) are more suitable.

For soft BCLs, the steepest base curve that will allow minimum lens movement without it adhering to the eye should be chosen as the initial trial lens. Instilling a drop of anesthetic will help make the insertion hassle-free for the ECP and pain-free for the patient. After the analgesic effect has worn off, patient comfort should be assessed and the BCL fit re-evaluated to ensure that it is centered, has good corneal coverage, is tighter than a conventional contact lens fit and is moving just a little.

With the right training about personal hygiene, lens insertion/removal, a lens care regime that includes digital rubbing and timely replacement, accidental decentration and loss of the BCL are unlikely. If the BCL falls out, it should be cleaned thoroughly and re-inserted or thrown out and a new BCL inserted. The patient should be encouraged not to touch/rub the eye or reposition the lens, except to protect it with ocular lubricants. An aerated eye shield can be worn at night if the patient has nocturnal lagophthalmos and sunglasses can be worn during the day for light-sensitivity symptoms.

The patient should be counselled that they need to be seen frequently by their ECP because the eye that requires the BCL is already compromised and wearing a BCL is not without risk. The risk of microbial infection or even ulceration is higher than normal so consider using an initial supportive collagen shield soaked in antibiotic and steroid medication that dissolves within 12 hours, then covered by a BCL, for example. Alternatively, a stand-alone BCL that allows for adjunct therapies such as delivery of drugs and ocular lubricants is equally as effective.

Patients should use their BCLs for as long as required for the basement membrane to regenerate and for the tight junctions in the epithelium to restore adhesion. They must also use antibiotics due to the increased risk of infection with extended wear contact lenses (EWCLs) for as long as they are wearing BCLs.

In easy cases, it might take as little as one day for the cornea to completely heal, as in mild RCE. On the other hand, it might take as long as several years in complicated, chronic cases – persistent epithelial defects or bullous keratopathy, for example. Patients with longstanding BCLs can be monitored regularly, every one to three months, with a change in antibiotics every three months to prevent drug resistance.

In summary, BCLs are effective and can safely be used, with topical antibiotic coverage when necessary, to protect the ocular surface when it is healing from diseases and after injuries and surgeries. When applied early in the treatment plan, a permanent reduction in visual acuity is unlikely. Patients also benefit and appreciate the pain relief they inherently bestow. BCLs are rewarding and patients will love you for them!

By Shirley Ha, HBSc., O.D.

Coloured contact lenses are back in the limelight. Even Oprah is wearing them on the cover of the October 2014 issue of O, The Oprah Magazine. You can’t help but be drawn to the dramatic transformation effected by her Pure Hazel lenses, one of nine shades available from the newly launched line of AIR OPTIX® COLORS contact lenses from Alcon. The patented 3-in-1 Colour Technology and silicone hydrogel material have come a long way from the unnatural-looking, dot matrix-patterned, non-disposable lenses introduced in the mid-1980s by Wesley-Jessen. Hopefully, the renewed interest in coloured contact lenses will remind eyecare practitioners that there are other applications for these medical devices – as fashion and beauty products.

Prosthesis

Prosthetic contact lenses can be life changing for patients with permanent disfigurements from congenital birth defects such as aniridia and iris coloboma, diseases such as corneal dystrophies and herpetic keratoconjunctivitis, and trauma/surgery, including lacerations, chemical burns and iridectomy.

Generally, they are used cosmetically to camouflage ocular anomalies and to make the diseased or damaged eye(s) look natural to the observer. In such cases, they help to reduce social distress and boost self-confidence.

Prosthetic contact lenses can be transparently tinted, opaque or hand-painted. They can range from something as simple as a clear lens with a black pupil to an off-axis pupil for disguising a strabismus, to an array of iris imprints, colours, pupil sizes, designs and styles. If the eye is blind, a black pupil may be used; otherwise, the pupil diameter that will provide good visual field in normal-to-bright light conditions should be selected. Sometimes, the whole lens diameter may be tinted to limit or eliminate the amount of light entering the eye, especially in patients with migraines, amblyopia, diplopia and extreme photophobia.

They are fitted for corneal coverage, centration and movement, as with any other soft or scleral contact lens, and they can be fitted with or without a prescription. In monocular cases, a digital photo can be sent to the lab for matching to the colour and iris details of the non-compromised eye.

Sports Vision

Like tinted sports goggles, custom-tinted contact lenses can help to maximize contrast, reduce glare and improve depth perception, but without the decreased field of view caused by the frame apparatus, especially for athletes who want to enhance their sports experience and/or gain a competitive advantage. As a general guide, green-grey tints increase the definition/contrast of contour cues, such as the fairway in golf, the yellow ball against the blue sky in tennis, subtle terrain details in skiing, and a brown critter against green foliage in biking/hunting. In skeet shooting, yellow or brown with red-orange tints can increase both the contrast and depth perception of the reddish-orange clay against its background, and help track, brighten and sharpen the details of low-contrast objects, such as a baseball or a soccer ball in overcast, foggy, low-light conditions.

Colour Vision Deficiencies

Colour vision deficiencies affect about 8 per cent of men and 0.4 per cent of women. Most are hereditary, while a few are caused by ocular diseases such as ARMD and glaucoma. There is no known cure for the inherited form of the condition. Art Optical has a FDA-cleared lens called the X-Chrom^® lens. When worn monocularly and over the non-dominant eye, this reddish-tinted therapeutic lens can increase the perception of the red and green wavelengths of light entering the eye such that a person with dichotomous Protan and/or Deutan deficiencies can better detect or differentiate the previously ambiguous figure from the ground in pseudoisochromatic plates tests. The dominant eye without the therapeutic lens continues to have “normal” vision because the blue and yellow wavelengths are not affected.

Other Applications

Some low vision patients with significant glare/photophobic symptoms and reduced acuities from ocular diseases such as albinism, peripheral cone dystrophy and macular degeneration have benefited from red-, yellow- and green-tinted contact lenses. Blue tints have been helpful in reducing light-sensitivity symptoms in traumatic brain-injured patients and also in increasing reading speed in poor readers. Other applications include decorative/novelty or special effects contact lenses for Halloween and other special events and for the TV/movie industry.

Coloured contact lenses can be utilized in various ways, depending on the patient’s needs. Whether their intended use is as fashion accessories, for vision enhancement for recreational purposes, or as treatment for an ocular condition, they remain medical devices and require ongoing contact lens follow-ups to ensure effective lens performance and optimum corneal health.

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CASSEL, M. “Changing Lives with Prosthetic Soft Lenses”, Contact Lens Spectrum, April 2010

Ciba Vision ECP Letter: “Product Discontinuation Information”, June, 2011, p. 5

BIRCH, J. “Worldwide prevalence of red-green color deficiency”, Journal of the Optical Society of America. A, Optics, image science, and vision, vol. 29, n^o 3, March 2012, p. 313-20

ZELTZER, H. The X-Chrom Manual, Second Edition, Massachusettes, 1982, 20 p.

By Shirley Ha, HBSc., O.D.

Since they debuted as glass-blown “shells” in 1887, scleral lenses have been in and out of favour. Most recently, they have made a comeback on the contact lens scene. The success of the vault-fitting principle in rehabilitating and correcting distorted and compromised anterior surfaces is undeniable but the expanded scope of use for scleral lenses to include normal eyes is fairly recent. Today, virtually every contact lens patient is a prospective scleral lens candidate, thanks to technological advances in lens designs, higher Dk materials, better manufacturing processes and unprecedented customization.

In general, sclerals are large-diameter rigid gas permeable lenses. The Scleral Lens Education Society (www.sclerallens.org) divides the lens into three categories based on size and bearing zone: Corneal (8.0-12.5 mm), Corneoscleral (12.5-15.0 mm) and Full Scleral (15.0-25.0 mm). They can be made in a range of shapes to suit any corneal profile, from very flat corneas to complex topographies.

The basic fitting philosophy and counseling for sclerals have not changed. They are not as intimidating to fit or any more time consuming than other specialty fits. However, having diagnostic trial scleral fitting sets with different base curves, diameters and peripheral curves is crucial. Depending on the lens designs, many are available on loan from the laboratory for trial fitting purposes.

In its simplest form, there are three parts to a scleral lens: the rise, the run and the diameter. The rise is the apical radius of curvature of the lens and depends on the most important metric, the sagittal height (SAG) or the anterior chamber depth of the eye. The run is the peripheral curve or how steep (oblate) or flat (prolate) the periphery is, relative to the base curve. The diameter is directly related to the SAG and can be increased or decreased to elevate the lens off the eye or lower the lens closer to the eye.

For the best fitting relationship, the central base curve of the scleral lens must completely vault over the cornea with good clearance over the limbus to protect the area from inflammation, in-growth and neovascularization. The peripheral curves should land uniformly or parallel to the scleral profile and not have uncomfortable edge lift or conjunctival vessel impingement.

The lens should move minimally, if at all. The apical tear clearance should be adequately exchanged via capillary attraction and not exceed 200 µm for a maximum 250 µm centre thickness lens. There should not be any lens flexure that can cause conjunctival blanching from the negative pressure effect produced in blinking. If fitted properly, scleral lenses are as comfortable as soft toric lenses. If there is initial discomfort, one or more of the lens parameters should be changed.

The purpose of the pre-corneal tear reservoir or chamber is two-fold: it takes the corneal refractive power out of the picture and enhances vision by creating a new spherical refracting plane, and it supports and protects the corneal physiology and surface integrity.

Due to the minimum lens translation, scleral lenses are the ideal choice for healthy eyes with high irregular astigmatism, especially prescriptions that are outside the available parameters or cannot be fitted properly with standard RGPs. Any over-refracted astigmatism not caused by flexure can be surfaced with front, back or quadrant-specific toricity in the optic zone of the lens. If warranted, a toric flange can be ordered for scleral toricity to better align the peripheral curves onto the sclera.

For oblate corneas with steeper peripheral curves than central curves, as in post-refractive laser surgery patients, reverse geometry corneoscleral lenses work well in correcting the modified corneal surface while alleviating the often comorbid dry eyes.

For presbyopes who drop out because their current contact lenses are no longer effective at near, multifocal scleral lens options are now available. Because the lenses are immobile, most laboratories use simultaneous image designs with near centre optics.

For the novice scleral lens fitter, A Guide to Scleral Lens Fitting by Eef van der Worp is a great place to start. Online communities such as the GP Lens Institution and the Scleral Lens Education Society provide forums, educational webinars, instructional tutorials, workshops and curricula to help professionals learn more about this specialty lens modality, including fitting guides for the different proprietary lens designs and materials, lens handling and care products. Through these online communities, scleral lens experts around the world review clinical cases and help troubleshoot fitting or complication challenges, such as decentrations, air bubbles, surface/reservoir deposits, non-wetting and corneal hypoxia.

Additionally, don’t forget to work with the clinical consultants at laboratories – they have a wealth of information about scleral lenses and are more than happy to impart their knowledge and experience to you. It is a journey that both you and your patients will find rewarding.

By Shirley Ha, HBSc., O.D.

The fitting of multifocal contact lenses (MFCLs) is becoming easier and less time-consuming than in years past. Beyond the customary presbyopia they were intended to correct, MFCLs are being considered for other uses such as slowing myopia progression in children and managing deficits in accommodation and some binocular disorders, especially for those averse to wearing glasses. To successfully fit these patients, it is important to understand the intricacies of the different multifocal lens designs, so that the most favourable profile can be chosen.

Currently, two basic designs are in use: the alternating image RGP-only design with distinct distance and near vision zones, and the simultaneous image design in which the distance, near and often intermediate images are simultaneously presented and the brain chooses the better resolution image. Simultaneous image designs use concentric, aspheric or a combination of both optics. Aspheric is the most common and incorporates a centre-near or a centre-distance design.

For myopia control, the premise is to reduce the peripheral hyperopic defocus, a stimulus for axial elongation in children. A simultaneous image concentric design bifocal contact lens seems reasonable, where an outer annular ring of retinal defocus surrounds a centre circle of distance correction. One study utilizing this concept found that 28 out of 40 children, aged 11-14, who wore a dual-focus lens in one eye had their myopia progression and axial elongation reduced by about 30 per cent or more compared with their other eye, which wore a single-focus lens. It concluded that sustained myopic defocus with simultaneous image design can slow myopic progression.[i]

Similarly, a centre-distance aspheric soft MFCL, such as the “D” design Biofinity^® and Proclear^® Multifocals from Cooper Vision with a high add power, can also work. According to a two-year study by Dr. Jeffrey Walline et al, 27 myopic children, aged 8-11, wearing two “D” lenses showed an impressive 50 per cent reduction in myopia progression, compared to children wearing single vision lenses in the control group. Axial growth was also reduced by 29 per cent.[ii]

Another centre-distance design, the Acuvue^® Oasys^® for Presbyopia from Vistakon, could be considered an option; however the net plus-power in its alternating distance and near zones in the periphery may not be enough to move the image back onto the retina to arrest ocular growth. The same is true of most of the centre-near aspheric soft MFCLs currently on the market, all of which are more suitable for correcting regular presbyopia.

Another possible use of MFCLs is for patients with accommodation anomalies, such as accommodative insufficiency or ill-sustained accommodation. When used as an adjunct to primary vision therapy, they are very effective and can provide the initial short-term solution or even the kick-start necessary for vision training. The goal is the same as it is for a presbyope whose loss of accommodation naturally decreases with age: to prescribe the lowest add correction that will bring the near point of focus clearly and comfortably within the patient’s normal working distance by harmonizing the abnormal clinical findings of low amplitude of accommodation for age, high lag of accommodation, low positive relative accommodation (PRA) and inertia of accommodation. In theory, both the alternating image and simultaneous image designs can be employed to manage these dysfunctions. In the end, however, the compensatory modality chosen, either multifocal spectacles or MFCLs, should be eliminated over time through active vision therapy.

Conversely, an alternating image design can be suggested for binocular dysfunction cases, such as non-refractive accommodative esotropia and convergence excess with high accommodative convergence/accommodation (AC/A) ratios to relax accommodation and promote ocular alignment at near. It is more natural and can even help reduce the neck muscle tension that is often found in some spectacle bifocal wearers. Furthermore, it is especially beneficial for plus prescriptions because less accommodation is needed to focus at near compared to plus-lens glasses due to the difference in vertex distance. A study conducted by Rich and Glusman from the University of South Alabama’s Department of Ophthalmology cites the alternating image design (Tangent Streak^® RGP bifocal contact lens) as an acceptable alternative to bifocal glasses for patients with accommodative esotropia.[iii]

The use of simultaneous image aspheric designs in managing this group in clinical trials is limited and has mixed results. One researcher reported the added plus near periphery was dynamically useful in all fields of gaze for his 15 children[iv] while another study failed to show adequate binocular alignment.[v] Notwithstanding research results that may still be forthcoming, all patients with accommodative esotropia should still undergo optometric vision training to eliminate any amblyopia/suppression and to build on improving the fusional divergence reserves at all viewing distances.

In summary, MFCLs are only effective if applied to the correct patients. Understanding the optical properties of MFCL profiles will provide the practitioner with the outside-the-box thinking and additional arsenal needed for that prospective uncommon clinical solution.