Convergence insufficiency
Encyclopedia
Convergence insufficiency or Convergence Disorder is a sensory and neuromuscular anomaly of the binocular vision
system, characterized by an inability of the eyes to turn towards each other, or sustain convergence
.
(double vision), asthenopia
(eye strain), transient blurred vision, difficulty sustaining near-visual function, abnormal fatigue,
headache
, and abnormal postural adaptation, among others.
Note that some Internet resources confuse convergence and divergence dysfunction, reversing them.
dysfunctions to rule out any organic disease. Convergence insufficiency characterized by one or more of the following diagnostic findings: High exophoria
at near, reduced accommodative convergence
/accommodation
ratio, receded near point of convergence, low fusional vergence ranges and/or facility.
and/or lenses
in addition to the therapy regime.
In 2005, the Convergence Insufficiency Treatment Trial (CITT) published two randomized clinical studies. The first, published in Archives of Ophthalmology
demonstrated that computer exercises when combined with in-office based vision therapy was more effective than "pencil pushups" or computer exercises alone for convergency insufficiency in 9 to 18 year old children. The second found similar results for adults 19 to 30 years of age.
Surgical correction options are also available, but the decision to proceed with surgery should be made with caution and only after all orthoptic efforts have failed.
Bilateral medial rectus resection is usually the most effective operation for convergence insufficiency. However, the patient should be warned about the possibility of uncrossed diplopia at distance fixation after surgery. This typically resolves within 1-3 months postoperatively. The exophoria at near often recurs after several years, although most patients remain asymptomatic.
s had convergence insufficiency and a Spanish study found that nearly 1 in 100 (0.8%) of symptomatic patients in an optometric clinic had CI. In contrast, studies conducted by the Southern California College of Optometry
found that approximately 1 in 8 (13%) of fifth and six grade children examined during visual screenings had the disorder as did nearly 1 in 5 (17.6%) of 8 to 12 year olds receiving examinations at optometry clinics. A recent Romanian study revealed that roughly 3 in 5 (60.4%) of young adult patients complaining of blurred vision at near work suffered from convergence insufficiency.
Binocular vision
Binocular vision is vision in which both eyes are used together. The word binocular comes from two Latin roots, bini for double, and oculus for eye. Having two eyes confers at least four advantages over having one. First, it gives a creature a spare eye in case one is damaged. Second, it gives a...
system, characterized by an inability of the eyes to turn towards each other, or sustain convergence
Convergence (eye)
In ophthalmology, convergence is the simultaneous inward movement of both eyes toward each other, usually in an effort to maintain single binocular vision when viewing an object. This action is mediated by the medial rectus muscle, which is innervated by Cranial nerve III...
.
Symptoms
The symptoms and signs associated with convergence insufficiency are related to prolonged, visually demanding, near-centered tasks. They may include, but are not limited to, diplopiaDiplopia
Diplopia, commonly known as double vision, is the simultaneous perception of two images of a single object that may be displaced horizontally, vertically, or diagonally in relation to each other...
(double vision), asthenopia
Asthenopia
Asthenopia or eye strain is an ophthalmological condition that manifests itself through nonspecific symptoms such as fatigue, pain in or around the eyes, blurred vision, headache and occasional double vision...
(eye strain), transient blurred vision, difficulty sustaining near-visual function, abnormal fatigue,
headache
Headache
A headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...
, and abnormal postural adaptation, among others.
Note that some Internet resources confuse convergence and divergence dysfunction, reversing them.
Diagnosis
Diagnosis of convergence insufficiency is made by an eye care professional skilled in binocular visionBinocular vision
Binocular vision is vision in which both eyes are used together. The word binocular comes from two Latin roots, bini for double, and oculus for eye. Having two eyes confers at least four advantages over having one. First, it gives a creature a spare eye in case one is damaged. Second, it gives a...
dysfunctions to rule out any organic disease. Convergence insufficiency characterized by one or more of the following diagnostic findings: High exophoria
Exophoria
Exophoria is a form of heterophoria in which there is a tendency of the eyes to deviate outward. During examination, when the eyes are dissociated by prisms, the visual axes will appear to diverge away from one another.-Prevalence:...
at near, reduced accommodative convergence
Accommodative convergence
Accommodative convergence is that portion of the range of inward rotation of both eyes that occurs in response to an increase in optical power for focusing by the crystalline lens .-See also:*Convergence insufficiency...
/accommodation
Accommodation (eye)
Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image on an object as its distance changes....
ratio, receded near point of convergence, low fusional vergence ranges and/or facility.
Treatment
Convergence insufficiency may be treated with convergence exercises prescribed by an eyecare specialist trained in vision therapy, orthoptics, and binocular vision anomalies. Some cases of convergence insufficiency are successfully managed by prescription of eyeglasses with therapeutic prismsPrism (optics)
In optics, a prism is a transparent optical element with flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use...
and/or lenses
Lens (optics)
A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element...
in addition to the therapy regime.
In 2005, the Convergence Insufficiency Treatment Trial (CITT) published two randomized clinical studies. The first, published in Archives of Ophthalmology
Archives of Ophthalmology
The Archives of Ophthalmology is a monthly professional medical journal published by the American Medical Association. Archives of Ophthalmology publishes peer-reviewed, original articles on such topics as epidemiology and biostatistics, mechanisms of ophthalmic disease, ophthalmic molecular...
demonstrated that computer exercises when combined with in-office based vision therapy was more effective than "pencil pushups" or computer exercises alone for convergency insufficiency in 9 to 18 year old children. The second found similar results for adults 19 to 30 years of age.
Surgical correction options are also available, but the decision to proceed with surgery should be made with caution and only after all orthoptic efforts have failed.
Bilateral medial rectus resection is usually the most effective operation for convergence insufficiency. However, the patient should be warned about the possibility of uncrossed diplopia at distance fixation after surgery. This typically resolves within 1-3 months postoperatively. The exophoria at near often recurs after several years, although most patients remain asymptomatic.
Prevalence
A British survey found that less than 1 in 300 patients receiving optometric eye examinationEye examination
An eye examination is a battery of tests performed by an ophthalmologist, optometrist, or orthoptist assessing vision and ability to focus on and discern objects, as well as other tests and examinations pertaining to the eyes....
s had convergence insufficiency and a Spanish study found that nearly 1 in 100 (0.8%) of symptomatic patients in an optometric clinic had CI. In contrast, studies conducted by the Southern California College of Optometry
Southern California College of Optometry
Southern California College of Optometry is a private, 4-year university, founded in 1904 and is located in Fullerton, California. The college offers a post-baccalaureate program leading to the degree, Doctor of Optometry ....
found that approximately 1 in 8 (13%) of fifth and six grade children examined during visual screenings had the disorder as did nearly 1 in 5 (17.6%) of 8 to 12 year olds receiving examinations at optometry clinics. A recent Romanian study revealed that roughly 3 in 5 (60.4%) of young adult patients complaining of blurred vision at near work suffered from convergence insufficiency.
See also
- AmblyopiaAmblyopiaAmblyopia, also known as lazy eye, is a disorder of the visual system that is characterized by a vision deficiency in an eye that is otherwise physically normal, or out of proportion to associated structural abnormalities of the eye...
- Negative relative accommodationNegative relative accommodationNegative relative accommodation was proposed by Prof. Joseph Kearney of Oxford University in 1967, is a measure of the maximum ability to relax accommodation while maintaining clear, single binocular vision. This measurement is typically obtained by an orthoptist, ophthalmologist or optometrist...
- Positive relative accommodationPositive relative accommodationPositive relative accommodation is a measure of the maximum ability to stimulate accommodation while maintaining clear, single binocular vision. This measurement is typically obtained by an orthoptist, ophthalmologist or optometrist during an eye examination using a phoropter...
- StrabismusStrabismusStrabismus is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles, which prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely...
- Orthoptics
- OphthalmologyOphthalmologyOphthalmology is the branch of medicine that deals with the anatomy, physiology and diseases of the eye. An ophthalmologist is a specialist in medical and surgical eye problems...
- OptometryOptometryOptometry is a health care profession concerned with eyes and related structures, as well as vision, visual systems, and vision information processing in humans. Optometrists, or Doctors of Optometry, are state licensed medical professionals trained to prescribe and fit lenses to improve vision,...
External links
- www.convergenceinsufficiency.org
- College of Optometrists in Vision Development
- International Orthoptic Association
- New York Times article on convergence insufficiency
- Vision Disorder Responds Best to Office-Based Therapy Combined with Home-Based Computer Therapy peer-reviewed article from MedPage TodayMedPage TodayMedPage Today is an online medical news service for physicians and healthcare professionals and is based out of Little Falls, New Jersey. The site provides breaking medical news, professional medical analysis and continuing medical education credit for reading articles and answering a short series...