Accommodative Insufficiency and Convergence Excess
Convergence Excess and Accommodative Insufficiency are intricately linked, a connection that often goes unnoticed. Understanding this relationship can provide a deeper insight into the complexity of vision disorders.
What is Accommodative Insufficiency
Accommodative Insufficiency is a dysfunction of the accommodative system, which is the ability of the eye to change its focus from distant to near objects. Accommodative insufficiency is a focusing problem, particularly at near. This does not necessarily relate to an acuity or general clarity of vision problem. Accommodation dysfunction relates to difficulties maintaining accurate and comfortable focus.
Generally, accommodative dysfunction is not related to "weak muscles". Sometimes, a child may fail to establish adequate focusing skills during their early development years. In the majority of cases, accommodative dysfunction relates to fatigue from sustained near tasks, often in demanding learning environments. The effort required to maintain convergence and accommodation can lead to a breakdown in the efficiency and functionality of the accommodative convergence system.
This is also why accommodative dysfunction tends to be acquired and may exist in the background sometime before symptoms first appear.
Symptoms of Accommodative Insufficiency
Symptoms associated with accommodative dysfunction are like those reported for convergence excess and include,
Visual discomfort – red or sore eyes, transient distance or near blur and headaches, usually frontal or temporal.
Difficulty sustaining near-visual attention may result in avoidance or increased visual stress.
Glare sensitivity and dizziness
Rapid fatigue, even with small amounts of close work
Abnormal posture adoption, head tilt, and pulling work closer or further away.
What is Convergence Excess
Convergence excess is a sensorimotor anomaly of the binocular vision system, which is the brain's ability to create a single, three-dimensional image from the two separate images received from each eye. Convergence excess is characterised by a tendency for the eyes to over-converge at near. Simply put, the eyes aim too close or in front of the reading material.
Symptoms of Convergence Excess
Symptoms include:
Reduced efficiency and productivity/diminished accuracy/inconsistent work product
Diminished performance with time in task
Diplopia (double vision)/tendency to close or cover one eye
Transient blurred vision/illusory movement
Loss of place, repetition and/or omission of words and/or lines of print while reading
Transposition when copying from one source to another
Pain in or around the eye
Headaches
Difficulty sustaining near-visual function
Avoidance of visually demanding tasks
Inaccurate eye-hand coordination
Abnormal postural adaptation/abnormal working distance
Spatial disorientation
Photophobia (sensitivity to light)
Inconsistent visual attention/concentration and/or awareness
Distractibility while performing visually demanding tasks
General fatigue
Awareness of the need for volitional control of the eyes
Asthenopia (eye strain)
Difficulty changing fixation from near to far
The above range of symptoms is often abbreviated to eye strain, headaches, fatigue and blurred vision.
Convergence excess primarily affects near-work tasks, especially reading and writing. The most common symptom is eye strain, however, when the near vision system is not functioning effectively, as seen above, a wide range of symptoms can develop.
An adaptive change often observed in Convergence Excess cases is for the subject to move their near work closer to see better. In this instance, the body is seeking to resolve and relieve symptoms related to convergence excess. Another way of resolving the binocular vision mismatch is to close one eye and read with the dominant eye, thereby reducing the strain of trying to coordinate and use both eyes together.
The Link Between Accommodation and Convergence
Excess convergence is often associated with accommodative Insufficiency as the accommodative system and convergence system are linked. The eyes converge when one accommodates (to focus on a near object). Similarly, when one converges, the accommodative system is also activated.
In cases of convergence excess, the eyes often aim closer to stimulate the accommodative system and increase focusing ability. The resultant mismatch between vergence and focus falls under the umbrella term binocular vision dysfunction and can have a profound impact on visual comfort.
Treatment Options for Convergence Excess Accommodative Insufficiency
Therapeutic spectacles lenses.
These lenses are most often prescribed in a multifocal format. They are typically used for near tasks – reading, writing, computer use - where a near addition is prescribed to relax and improve near focus. The lens's multifocal format helps maintain clear distance vision, where the additional near-plus power is not required. The lenses aim to relax, focusing effort. This reduces the need to pull the eyes closer, thereby stimulating accommodation, and improves near vision comfort and focusing efficiency. In many cases, spectacles are all that is required.
Vision Therapy (in addition to therapeutic spectacles)
Vision therapy is a personalised program that uses exercises to retrain the accommodative convergence system to regain binocular vision control. The exercises may also include the use of prisms and lenses.
Vision therapy alone does not alleviate the symptoms associated with convergence excess-accommodative insufficiency, and it may take some time before fatigue and other symptoms diminish.
Visual Hygiene
Visual hygiene involves habits that reduce eye strain during near tasks, helping manage Convergence Excess and Accommodative Insufficiency. Key practices include:
Regular Breaks: Follow the 20-20-20 rule to relax focus and convergence.
Proper Distance: Maintain an elbow-to-fist distance from reading material.
Good Lighting and Posture: Minimise unnecessary visual strain.
Limit Prolonged Near Work: Take frequent pauses to prevent fatigue.
These habits reduce visual stress, easing symptoms like eye strain, headaches, and blurred vision.
Prism Adaptation
There is controversy on the benefits of prescribing corrective prism spectacles to alleviate symptoms in convergence excess.
Opinions vary on the benefit of prescribing prism in general binocular vision disorders. Prism is prescribed more commonly in the treatment of intractable diplopia cases (double vision that cannot otherwise be resolved).
The main argument against prescribing prism in cases of convergence excess is that the corrective prism allows the eyes to remain in the incorrect or "over-converged" position. Over time, the patient adapts to the prism, and progressively higher degrees of prism are required to relieve symptoms.
However, prisms are used in many beneficial ways in vision therapy, brain injury, concussion and stroke cases.
Accommodative Insufficiency and Convergence Excess can significantly affect near-vision tasks, causing discomfort and reduced productivity. Early diagnosis and treatment, such as therapeutic lenses or vision therapy, can improve visual comfort and function.
Experiencing symptoms? Contact us at For Eyes Optometrist for a comprehensive eye examination and vision therapy consultation.
