Convergence insufficiency is a common binocular vision disorder where the eyes struggle to work together when focusing on objects up close. This sensory and neuromuscular issue impacts the visual system, affecting the ability of both eyes to turn inward, or converge, properly. It can affect both children and adults.
Understanding Convergence Insufficiency
Normal vision involves the eyes making coordinated adjustments to form a single, clear image. When shifting focus from a distant object to one nearby, the eye’s lens changes shape, the pupil constricts, and both eyes move inward toward the midline. This inward movement is called convergence. With convergence insufficiency, the brain and eyes may have difficulty coordinating these changes, sometimes causing one eye to turn outward instead of converging. This makes it difficult for the eyes to maintain a single, focused image for near tasks.
Everyday Examples of How It Affects Vision
Convergence insufficiency can manifest in various ways, particularly during close-up visual work like reading. Individuals might experience words appearing blurry or doubled, or they may lose their place frequently while reading. This can lead to re-reading sentences or paragraphs to grasp the content.
Physical symptoms often accompany these visual difficulties, including eye strain, headaches, and eye fatigue. Some people report a pulling sensation around their eyes or that print seems to move, jump, or float on the page. Children may exhibit behaviors such as rubbing their eyelids, shaking their head, squinting, or closing one eye to alleviate symptoms. Adults might notice increased sleepiness when performing prolonged near tasks or experience motion sickness or vertigo. Symptoms often worsen with fatigue or extended periods of close visual work.
Diagnosing Convergence Insufficiency
Diagnosing convergence insufficiency involves a comprehensive eye exam performed by an eye care professional. The examination includes a detailed history of the patient’s symptoms. Eye doctors assess how well the eyes work together and measure convergence ability.
Specific tests include the near point of convergence (NPC) test, which measures the closest point to the face where the eyes can maintain focus without double vision. For individuals with convergence insufficiency, the near point of convergence is receded, usually more than 6 centimeters from the face. Other assessments, like positive fusional vergence tests, determine the eyes’ ability to converge inward. Eye movement assessments, including vergence facility testing, also help evaluate the speed and ease with which the eyes can converge and diverge.
Effective Treatment Options
Several treatment approaches are available for convergence insufficiency, with the goal of improving the eyes’ ability to converge accurately and comfortably. Vision therapy, which includes specific eye exercises, is a primary treatment. This therapy trains the eye muscles and the brain-eye connection to improve convergence and eye teaming. Many patients experience improvements within about 12 weeks.
Another treatment option involves the use of prism lenses in glasses. These special lenses redirect light, reducing the amount of inward turning the eyes need to perform. While prism lenses can alleviate symptoms, they do not correct the underlying issue and require continuous wear. In rare circumstances, surgical intervention may be considered, though it is less common due to the effectiveness of vision therapy.