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Binocular Functions
· What are Binocular Functions? · Problems with Binocular Functions · Improving Binocular Functions · Causes · Types · Options · Tips
"Binocular functions refer to the ability of the eyes to coordinate their activity so that we can merge the visual fields of both eyes into one distinct image. The most commonly observed aspects of binocular functions include convergence (the ability of the two eyes to team and focus on the same object), and accommodations (the ability of the eyes to shift their focus from near point to far point or vice versa). Each eye can have normal acuity (20/20 vision) but unless the eyes team, visual functions are impaired."
Problems with Binocular Functions "The following are issues that may occur in a person experiencing difficulties with binocular functions:
∙ Difficulty going down stairs
∙ Poor eye-hand coordination
∙ Pain, watering, discomfort when required to perform visual work
∙ Inability to read without losing place
∙ Rubbing eyes after use
∙ Frequent headaches after visual work
∙ Frequent stomach aches after visual work
∙ Difficulty copying from the board
∙ Generalised light sensitivity (photophobia)
∙ Poor three-dimensional perception
∙ Difficulty in sustaining eye contact"
By improving the binocular functions of your eyes, such as convergence and divergence, you can improve your peripheral and central vision. Some methods for improving binocular functions are:
· Vision Suggestions: Three-Dimensional Stereo Images · Bates Method Exercises · Palming · Swinging · Sunning · Fusion · Suggestions listed in the table of contents on the 'Vision Suggestions' page under the 'Binocular Functions' heading (e.g. Accommodative Insufficiency).
"Amblyopia, which usually begins in infancy or childhood, is a condition of poor vision in an otherwise healthy eye because the brain has learned to favor the other eye. Although the eye with amblyopia often looks normal, there is interference with normal visual processing that limits the development of a portion of the brain responsible for vision." EyeMDLink.com: Reduced Daily Eye Patching Effectively Treats Childhood's Most Common Eye Disorder
· Laterality: Determining Laterality: Determining Eye Dominance
“Since amblyopia usually occurs in one eye only, many parents and children may be unaware of the condition. Far too many parents fail to take their infants and toddlers in for an early comprehensive vision examination and many children go undiagnosed until they have their eyes examined at the eye doctor's office at a later age.” Optometrists Network: About Amblyopia (Lazy Eye)
“The most important diagnostic tools are the special visual acuity tests other than the standard 20/20 letter charts currently used by schools, pediatricians and eye doctors. Examination with cycloplegic drops can be necessary to detect this condition in the young.” Optometrists Network: About Amblyopia (Lazy Eye)
"The most common causes of amblyopia are · Crossed or wandering eyes or · Significant differences in refractive error, such as farsightedness or nearsightedness, between the two eyes." EyeMDLink.com: Reduced Daily Eye Patching Effectively Treats Childhood's Most Common Eye Disorder
Different Treatments "Research has shown that amblyopia associated with anisometropia [a condition of unequal refractive state for the two eyes] has different characteristics than amblyopia associated with strabismus [cross eyes]. Therefore the occlusion and treatment modes are slightly different for the two types of amblyopia." Indiana University School of Optometry: Course V755-Basic Vision Therapy
Amblyopia with Strabismus · "Patients with strabismic amblyopia may be treated at any age, however, the clinician must consider eccentric fixation. · The preferred type of occlusion to be used in strabismic patients with NRC is constant direct occlusion [occluding the non-amblyopic eye]. · If the patient has eccentric fixation, some clinicians occlude the amblyopic eye to keep them from using the eccentric point. · The length of occlusion is determined by the age of the patient. Occlusion sustained too long in a preschool aged child may be detrimental to the vision in the non- amblyopic eye (so-called ‘occlusion amblyopia’). · The method commonly used is 1 day per week for each year of age, on successive days. · Treatment is continuous until 6-8 weeks after last measured improvement." Indiana University School of Optometry: Course V755-Basic Vision Therapy
· "Full-time occlusion in anisometropic amblyopia is contraindicated [meaning inadvisable] because these patients often have partial binocular vision. Constant occlusion may precipitate strabismus and loss of fusion. · Part-time direct occlusion is the preferred method. · Combined with binocular enhancement procedures, 2 to 6 hours per day [2 to 6 hours per day for occlusion-not for binocular enhancement procedures], every day, is sufficient. Treatment continues for 6-8 weeks after last measured improvement." Indiana University School of Optometry: Course V755-Basic Vision Therapy
· Vision: Binocular Functions: Convergence Insufficiency · Vision: Binocular Functions: Accommodative Insufficiency · Vision: Binocular Functions: Anisometropia
"Amblyopia therapy may consist of one or more of the following: · Optical Correction [lenses] · Passive Therapy [blocking one eye] · Active Therapy [e.g. hand-eye coordination exercises] · "Cam" therapy [not proven] · Pleoptics [not proven]" Indiana University School of Optometry: Course V755-Basic Vision Therapy
"Patching the unaffected eye of children with moderate amblyopia for two hours daily works as well as patching the eye for six hours. This research finding should lead to better compliance with treatment and improved quality of life for children with amblyopia, or 'lazy eye,' the most common cause of visual impairment in childhood." EyeMDLink.com: Reduced Daily Eye Patching Effectively Treats Childhood's Most Common Eye Disorder
"Dr. Sieving said it is crucial for young children to comply with the recommended treatment because visual impairment can persist into adulthood if amblyopia is not successfully treated in early childhood. Amblyopia is the most common cause of monocular (one eye) visual impairment among children and young and middle-aged adults." EyeMDLink.com: Reduced Daily Eye Patching Effectively Treats Childhood's Most Common Eye Disorder
"Patching the unaffected eye has been the mainstay of amblyopia treatment for decades. In March 2002, the same researchers reported the effectiveness of a second treatment, which involved using atropine eye drops that dilated the unaffected eye, temporarily blurring vision. Both treatments force the child to use the eye with amblyopia, stimulating vision improvement in that eye by helping the part of the brain that manages vision to develop more completely." EyeMDLink.com: Reduced Daily Eye Patching Effectively Treats Childhood's Most Common Eye Disorder
"Parents in both groups were advised that the daily hours of patching should be continuous when possible. In addition to patching, parents were instructed to have the child spend at least one of the hours of patching time each day doing 'near' visual activities, such as · reading, · writing homework assignments, · making crafts, · coloring, · tracing, · cutting out objects, · connecting dots, · doing hidden pictures and word finds, · playing computerized video games, or other activities requiring eye-hand coordination. Instructions of one hour of near activities were identical in both the two-hour and six-hour patching groups." EyeMDLink.com: Reduced Daily Eye Patching Effectively Treats Childhood's Most Common Eye Disorder
"Vision in the unaffected eye decreased by either one or two lines on the standard eye chart in about 21 percent of patients in the two-hour group, and about 24 percent of patients in the six-hour group. However, this is normal for patients with amblyopia, and vision in the unaffected eye is expected to return to normal when treatment is completed." EyeMDLink.com: Reduced Daily Eye Patching Effectively Treats Childhood's Most Common Eye Disorder
"Researchers note that the amount of vision improvement after four months in the eye with amblyopia should not be considered to be the maximum amount of improvement that can occur with patching. Instead, four months represented the maximum length of time they believed the treatments could be maintained in the study before either increasing the prescribed number of hours of patching or switching to an alternate treatment for amblyopia might be necessary." EyeMDLink.com: Reduced Daily Eye Patching Effectively Treats Childhood's Most Common Eye Disorder
“Passive therapy means only using occlusion. · Methods of occlusion · Schedule for occlusion Indiana University School of Optometry: Course V755-Basic Vision Therapy: Passive Therapy
“NeuroVision is the only treatment for Amblyopia or ‘Lazy Eye’ in older children and adults which is approved by the US FDA and the European CE Mark. Have a clearer and sharper vision in your ‘Lazy Eye’ and enjoy a better quality of vision – as experienced by hundreds of NeuroVision customers.” http://www.neuro-vision.com/amblyopia/amb_treatment.html
“Since NeuroVision received FDA approval for amblyopia treatment in 2001 and the European CE Mark for low myopia and amblyopia treatment in 2002, the company has garnered several significant milestones. In 2003, NeuroVision successfully completed a Myopia Study with the Singapore Eye Research Institute and in 2004, began commercial operations in Singapore, opening three NeuroVision centres within six months. This year NeuroVision began regional expansion in the Asia-Pacific and will begin expansion into Europe and the United States in 2006.” Business Wire: 'NeuroVision to Present at Medtech Insight's ''Investment In Innovation'' Conference'
“We are currently exploring the utility of visual deprivation to enhance the cortical response to reverse occlusion [the nondeprived eye is occluded]. Visual deprivation also induces a significant decrease in the level of GABAARs relative to AMPARs, and a return to the juvenile form of NMDARs in the visual cortex, two molecular changes that we propose enable the reactivation of ocular dominance plasticity in the adult visual cortex.” University of Maryland: Department of Biology: Faculty: Elizabeth M. Quinlan, Ph.D.
· Other Suggestions: Mirror Work: Things to Consider: Amblyopia
Passive Therapy: Staying Up Late If you're using passive therapy (blocking one eye) to treat your amblyopia, it might be a good idea to block one eye if you're up late and reading or watching TV. When the eyes are tired we tend to depend more on the other eye.
"Dr. Repka said having the child perform one hour of ‘near,’ or close-up, work per day [such as coloring, tracing, reading, and crafts] while patched was an important part of the prescribed treatment. He said it remains unclear if the same amount of visual improvement would occur with patching alone. 'We are planning a clinical trial to address the importance of near work in the treatment of amblyopia,' he said." EyeMDLink.com: Reduced Daily Eye Patching Effectively Treats Childhood's Most Common Eye Disorder
· Research Topics: Hypervigilence
Warning: Looking too far to either the left or to the right for even short durations of time can temporarily impact your hemispheric dominance. For more information please see the section on the ‘Laterality’ page concerning lateralized goggles and the dual-brain psychology research topic. Note: If you have amblyopia that is caused by anisometropia you may find it necessary to take steps to improve your convergence and accommodation. “’Ocular dominance reverses as a function of horizontal gaze angle.’ [I’m assuming that this means that looking to the left stimulates the right eye, if the right eye is uncovered, and vice versa (e.g. dual-brain psychology)] Ocular dominance is the tendency to prefer visual input from one eye to the other [e.g. Porac, C. & Coren, S. (1976). The dominant eye. Psychological Bulletin 83(5), 880-897]. In standard sighting tests, most people consistently fall into either the left- or right eye-dominant category [Miles, W. R. (1930). Ocular dominance in human adults. Journal of General Psychology 3, 412-420]. Here we show this static concept to be flawed, being based on the limited results of sighting with gaze pointed straight ahead. In a reach-grasp task for targets within the binocular visual field, subjects switched between left and right eye dominance depending on horizontal gaze angle. On average, ocular dominance switched at gaze angles of only [at least] 15.5 degrees off center.” Vision Reseach (Journal): 'Ocular dominance reverses as a function of horizontal gaze angle'
Some computer programs are oriented in a way that may force you to spend most of your time looking at one part of the screen. If your monitor is positioned directly in front of you, and you are using a computer program, you may be spending much of your time looking either to the left or to the right. This can exacerbate amblyopia. For example, if you are right hand dominant, and you spend much of your time looking to the left, this can increase your left-eye dominance because the left eye would be closer to the object on the screen. To prevent this you may need to reposition your monitor so it is further to the right if you are right handed, or further to the left if you are left handed.
The palming exercise may be helpful for resting the eyes before or after amblyopia therapy.
"Unfortunately many clinicians are still prescribing black 'pirate' patches. These are rarely required. New methods of occlusion are now available." The Low Vision Gateway: Diplopia
· Vision: Nutritional Optometry: Functional Photophobia · Laterality: Problems with Dominance: Developmental Causes · Laterality: Determining Laterality: Determining Eye Dominance · Laterality: Correcting Laterality: Correcting Eye Dominance · Laterality: Binocular Convergence and Photophobia · Sleep: Sleep on Your Back: Don't Sleep on Your Side or Stomach
What is Anisometropia? "Anisometropia is a condition where there is a significant difference in the refractive errors of the two eyes." Dr. William Stacy : Anisometropia
Effects Amblyopia, Lazy Eye "If this condition is present in infancy and is undetected or untreated, it often results in the development of lazy eye or amblyopia in the more hyperopic (far-sighted) eye. The greater the amount of the difference, the more likely the development of lazy eye will be." Dr. William Stacy : Anisometropia
Glasses "Another problem can occur when glasses are made for an anisometropic individual. The difference in the powers of the lenses induce a prismatic difference that can cause double vision in off-center areas of the lens, which can be compensated for by the use of slab-off prism." Dr. William Stacy : Anisometropia
Related Topics Amblyopia · Binocular Functions: Amblyopia: Types
Light Sensitivity · Binocular Functions: Light Sensitivity: Functional Photophobia, Covering One Eye
Accommodation · Binocular Functions: Accommodative Insufficiency · Vision: Bates Method: Accommodation: Changing Focus, Room Lighting · Vision: Bates Method: Accommodation
Conscious and Subconscious Vision MedicineNet.com: Peripheral Vision
Unconscious Vision Bates Method: Unconscious Vision
Central and Peripheral Vision "If you divide our brain into the conscious and subconscious, you could say that cone (central) vision is processed consciously, whereas rod (peripheral) vision is processed subconsciously. At most times, your subconscious mind functions in the background, sifting through huge streams of information for your conscious mind to consider."
"Components of Vision. There are two components of the visual system, focal (fovea) visionand ambient (peripheral) vision. Focal vision is primarily responsible for object recognition, and ambient vision is primarily responsible for spatial orientation.
· Ambient Vision. Ambient vision is often referred to as peripheral vision. It is a subconscious function independent of focal vision whose primary role is to orient an individual in the environment. For example, one can fully occupy focal vision by reading (a conscious action), while simultaneously obtaining sufficient orientation cues with peripheral vision to walk (a subconscious function). The same can happen when flying an aircraft and performing a task such as interpreting radar contact information on a HUD. Focal vision is used to consciously decipher task-oriented information while peripheral information is subconsciously used to maintain spatial orientation." USAF: Night Vision Goggles (Word Document, 1.47 MB)
Improving Peripheral and Central Vision · Binocular Functions: Improving Binocular Functions · Other Suggestions: Distractions
· Vision: Binocular Functions: Convergence Insufficiency · Vestibular System: Auditory (Inner Ear): Problems Caused by Virtual Reality?
What is Diplopia? "Double vision (diplopia) is one of the most troublesome visual disorders a patient can experience. The ability to read, walk and perform common activities is suddenly disrupted."
Management "The management of double vision may include prisms, orthoptics, therapy, eye muscle surgery and occlusion."
Double Vision that is Unresponsive to Orthoptics, Prism and Surgery "When diplopia causes significant discomfort, and is not responsive to other therapies, occlusion may be used."
Alternatives to Eye Patches "Unfortunately many clinicians are still prescribing black 'pirate' patches. These are rarely required. New methods of occlusion are now available." The Low Vision Gateway: Diplopia
What is Strabismus? Note: Some cases of strabismus are not noticeable to the naked eye. “Strabismus is a condition where your eyes don't look toward the same object together. One eye moves normally, while the other points · In (esotropia or ‘crossed eyes’), · Out (exotropia), up (hypertropia) or · Down (hypotropia). Strabismus can lead to amblyopia. Strabismus is the physical disorder, and amblyopia is the visual consequence.” All About Vision: Problems and Diseases: Strabismus
Symptoms and Signs · “Newborns often appear to have crossed eyes due to a lack of developed vision, but this disappears as the infant grows. · True strabismus does not disappear as the child grows. · Visit your eyecare practitioner if you're unsure if your child is demonstrating true strabismus. · The earlier the diagnosis and treatment, the better the visual results.” All About Vision: Problems and Diseases: Strabismus
Causes “Strabismus may be caused by unequal pulling of muscles on one side of the eye or a paralysis of the ocular muscles.” All About Vision: Problems and Diseases: Strabismus
“Occasionally, when a farsighted child tries to focus to compensate for the farsightedness, he or she will develop accommodative strabismus. This condition usually appears before two years of age, and can occur as late as six.” All About Vision: Problems and Diseases: Strabismus
Treatment “Treatment for strabismus is similar to amblyopia treatment: · Vision therapy including patching or visual exercises, · Glasses with the correct prescription or bifocal or prism correction to aid in proper focusing, · Eyedrops to help focus, · Or surgery. Surgery will correct the misaligned eyes but cannot resolve amblyopia caused by strabismus.” All About Vision: Problems and Diseases: Strabismus
“Before scheduling a child for surgery, some eyecare practitioners inject the ocular muscles with Botox (botulinum), which temporarily relaxes the muscles. In some cases, strabismus is permanently corrected in this way.” All About Vision: Problems and Diseases: Strabismus
What is Suppression? “Q: My right eye is much weaker than my left eye. Is it very important for me to wear glasses? — N.D.P., Canada A: I tell my patients that it is probable · The weak eye will allow the stronger eye to take control of the vision system. · This may cause the weak eye to begin shutting itself off in the brain — we call this suppression. If you believe that two eyes are better than one, you don't want this to happen. Although small, there is a risk that the weaker eye will develop · An amblyopia (lazy eye) or · A strabismus (turned eye). · And, if the weaker eye loses its ability to see clearly and the stronger eye develops a problem, you could be stuck with an eye that doesn't see well [anisometropia]. My recommendation to my patients is to try to make both eyes see as well as they can both individually and together. — Dr. Dubow” All About Vision: Q & A on Miscellaneous Eye Problems
Related Topics · Vision: Binocular Functions: Amblyopia: Types · Vision: Binocular Functions: Anisometropia · Vision: Nutritional Optometry (includes information about photophobia) · Vision: Binocular Functions: Convergence Insufficiency
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