By Sarah McGoldrick
EYE AILMENTS – LAZY EYE. OFTEN MISDIAGNOSED AS BAD BEHAVIOUR OR ACTING OUT IN CLASS, AMBLYOPIA (LAZY EYE) IS OFTEN DIFFICULT TO RECOGNIZE BY PARENTS AND TEACHERS. THE CAUSES OF AMBLYOPIA CAN OFTEN BE THE RESULT OF MISALIGNED EYES OR STRABISMUS AS WELL AS HEREDITARY FACTORS.
‘Lazy Eye’ is a common non-clinical term usually used to denote either strabismus, aka an eye turn, or amblyopia. Amblyopia is a condition where the eye does not see clearly even when vision is compensated with lenses and where there is no health concern,” said Dr. Charles Boulet, owner of Diamond Valley Vision Care in Alberta. “Sometimes these come as a combined problem where there are an eye turn and the turned eye becomes amblyopic because it is much less dominant.”
According to the Doctors of Optometry Canada, it is estimated that two to four per cent of children under the age of six have amblyopia. He said parents and many medical and optometric practitioners have the idea that there is a developmental window during which vision can be modi ed and after which nothing can be done, but this is not the case.
In the past, the standard treatment for Amblyopia was eyeglasses, patching, eye drops or surgery.
“It is often assumed that the only way to ‘treat’ a turned eye is surgery. Research suggests that surgery is only sometimes helpful and carries many risks while modern Optometric Vision Therapy (OVT) is much safer and provides better functional results,” he said. “OVT takes time, and it is not well understood outside of the behavioural optometric community, but it is easily the most underutilized optometric specialty.”
Boulet said the principles of treatment of strabismus and amblyopia have not changed much themselves in the last few decades in OVT – this is because human brain physiology has not changed.
Innovations in technology and increased attention in research has meant that ophthalmology and orthoptics have both begun to adopt more OVT type strategies in addressing functional vision problems like strabismus and amblyopia.
“Medically, patching was once the primary means of treating these conditions, but we now know that patching is only marginally e ective in amblyopia, and can often increase the Percentage of Time Strabismic (POTS) among those with eye turns. In cases of strabismus and amblyopia, specialty prescribing is often the best rst step, and should be given great attention,” he said.
He noted the use of aniseikonic/ isophoric lens designs, now made relatively simple through ShawLens. com, can be an easy rst step in addressing the causes.
With this type of lens, the images are equalized at the retinal level. Sensory fusion can now occur. The patient can integrate the two images more easily. We’ve found through clinical research that the time was taken to correct the amblyopia is signi cantly reduced and, best of all, vision suppression using a patch or drops may not be necessary.
“Amblyopia, commonly referred to as lazy eye, is weakness of vision in an otherwise healthy eye. It is frequently associated with a blurred image from an uncorrected refractive error in one eye or mis-alignment of the images due to strabismus,” said Peter J Shaw OD, CEO Shaw Lens and Adjunct Associate Research Professor, University of Waterloo.
He said in either case the result is that the visual cortex of the brain is unable to fuse the images together as one. In order to deal with the image di erence and resultant disruption the brain actively inhibits and ignores the less viable image from one eye and over time this behavior, if left untreated, permanently impairs the resultant vision. Research has shown that this inhibition actually occurs in the brain and not the eye, so really, perhaps it should be called lazy brain.
“The most frequent causes of amblyopia is blurred vision due to anisometropia or anisometropic astig- matism,” he said. “These are common vision conditions that even when corrected with eyeglasses fail to fully remediate the problem. This can create an obstacle to fusion in visual cortex in the form of aniseikonia (unequally sized ocular images due
to spectacle image magni cation inequality).”
He said in order to increase the success in the treatment of amblyopia many optometrist specializing in developmen- tal vision employ the use of iseikonic corrective therapies including contact lenses, refractive procedures and iseikonic eyeglass lenses. Iseikonic therapies including iseikonic eyeglass lenses ensure that the images in the brain are equally sized and provide the necessary foundation to fully remediate the amblyopic vision.
“When all barriers to eye teaming are eliminated, the vision system can function as nature intended.
The results from iseikonic therapies can be dramatic with improvement in vision from mild to moderate straight eye, refractive amblyopia seeming to occur instantly,” he said. “Sometimes vision therapy is required to achieve the fullest vision potential, new techniques in therapy often include 3D games and eye-hand coordination tasks,” he said adding experts in vision agree that patching is no longer consid- ered a primary therapy for amblyopia.
“Teaching the eyes to work together provides a lasting and less invasive approach to successfully treating am- blyopia. Iseikonic lenses such as Shaw Lens provide the foundation to enable eye teaming,” he said.
Many ECPs are not familiar with the new forms of treatment for Amblyo- pia. It is recommended that they consult with an expert in the industry to ensure proper treatment.
“The best thing an ECP who is un- trained in managing these conditions can do is to search for a developmental optometrist whose practice emphasizes this type of work. Patients need to know that there is something that can be done, and that these are less medical conditions than functional ones, and the best trained to deal with theses are developmental optometrists,” said Boulet.
“These are not permanent conditions, necessarily, and in most cases great improvements can be made within 6 months or less. These cases should be monitored more closely and require active therapies. ECPs can certainly use prism and lenses to assist una ected clients and parents to understand to some degree how these conditions feel.”
He added ECPs should also remind people that these conditions are not a simple matter of seeing blur, but that vision is multifaceted and that these conditions will consequently impact on motor skills, cognitive skills, and emotional state.
It is often di cult to keep kids engaged in Vision Therapy. It can require many hours of work on the part of the child and the parent. Boulet said a team e ort is required on the part of all involved to see success.
“First, ensure there is an appropriate Rx in place. OD’s and MD’s all too often will prescribe the cycloplegic refraction as the baseline/habitual Rx. This is almost always contraindicated in children as they will most often choose to disregard
the Rx by looking over the top of the frame,” he said.
“Strabismus treatment, in particular, requires ongoing work at home, and the treating facility needs to work with the family to ensure they are on task and motivated. The referring ECP should ensure they check up with the family to also encourage adherence to the treatment program.”
He noted traditional eye patch treatments can still be useful, however, the variety of alternatives means kids should no longer have to wear them for extended periods of time.
“Patching was traditionally used as the sole primary treatment tool, with children wearing them full time for up to several years. We know that this approach often loosens binocular function and leads to increased time strabismic. Because vision is designed to be binocular, treatment is best approached as a binocular system, or at the outset at least as a bi-ocular system (each eye viewing di erent targets but in the same visual eld),” he said. “We also know that aniseikonic/ isophoric lens designs can also be more e ective than patching in cases of refractive amblyopia and that this ap- proach is often more agreeable to patients as it serves to boost binocular vision, not suppress it.”
He noted ECPs should do their research before recommending a surgical option. He noted surgery will have no impact on amblyopia if there is no strabismus. He said surgery can be helpful in some cases of immovable strabismus, but most often, these cases are not as- sessed by developmental optometry.
“The best approach in terms of safety, cost, and outcomes is to turn to OVT rst, then surgery, if it’s still indicated, followed again by OVT to reduce the need for repeat surgeries. Surgery approaches the visual system as a mechanical entity, so very much like an automobile or computer where if a part is out of alignment or no longer working, it simply needs to be ‘ xed’ or replaced,” he said.
“Human physiology is not at all like this and therefore, treatments by surgery often require repeat procedures because the brain still has not learned operatebothvisualchannelsasateam.”