Eye Accommodation

Eye Accommodation

Accommodation of the eye, or eye accommodation, is the eye’s extraordinary ability to modify the focal length of the lens by changing the curvature of the eye lens. Accommodation allows the eye to adjust focus from seeing things at a distance and “tune” itself to seeing nearer objects.

Similar to breathing or blinking, this process is a reflex action. It brings near objects into focus in three parts — thickening the lens, constricting the pupil and automatic inward rotation of the eyes (known as eye convergence).


What is Accommodation of the Eye?

To define accommodation of eye, we need to uncover the function of the eye’s lens and the action of the ciliary muscles (muscles that support the ligaments around your eye’s lens).

In resting state: The ciliary muscles are usually relaxed. During this time, the aqueous humour (spaced between the lens and the cornea) and vitreous humour (spaced between the lens and the retina) push outward on the sclerotic coat (the outermost membrane surrounding the eye), and the ligaments become tensed. This causes the lens to pull itself into a thin shape, resulting in a short focal length for distance vision.

Definition of accommodation of eye: When we need to see objects nearby, like a book or a smartphone screen, the ciliary muscles contract, so the ligaments pulling your lens taught relax, causing the lens to become more rounded and thicker. This adjustment enables your lens to refract light more powerfully and bring nearby objects into clear focus.


Process of Accommodation of Eye

The cornea (the transparent front part of the eye covering the iris and pupil), provides only 2/3 of the refractive power and the lens, 1/3 of it. However, it is our eye that changes the curvature of the lens during the accommodation process, and not the cornea.

Put simply, the cornea doesn’t naturally change shape. It is the changing of the thickness of the lens which lets you see longer or shorter distances.

But how does the eye accommodate? Here’s a breakdown of the process of visual accommodation:

1) Initial State: Resting Muscles
  1. In its resting state, the eye’s ciliary muscles are relaxed, and the eye is naturally set for focusing on distant objects. In this scenario, incoming parallel light rays from far-off objects converge accurately onto the retina.
  2. The crystalline lens, a crucial optical component of the eye, maintains a relatively flattened shape when the ciliary muscles are at rest. This configuration results in an extended focal length, aligning with the requirements of distant vision.
2) Encountering a Nearby Object

When your gaze shifts to a closer object, such as a book or smartphone screen, the magic of accommodation begins. Here’s how it unfolds:

  1. Your brain, through a process known as sensory feedback, recognises the need for closer focus. In response, it sends signals to the ciliary muscles, instructing them to tighten.
  2. As the ciliary muscles contract, a series of remarkable transformations occur within the eye. One of the most crucial changes involves the crystalline lens.
  3. The crystalline lens, which is typically pliable, becomes thicker and more rounded as the ciliary muscles tighten. This alteration in lens shape leads to a decrease in its focal length.
  4. With the lens now having a shorter focal length, it can converge incoming light rays more effectively. This focused convergence ensures that the image of the nearby object lands precisely on the retina, creating a sharp and clear image.
        3) Seamless Adjustment

        The entire process of visual accommodation happens seamlessly and almost instantaneously. Your eyes adapt effortlessly to the varying distances of objects, allowing you to navigate the visual world without conscious effort.

        4) Release of Accommodation

        When you shift your focus back to a distant object, the ciliary muscles relax, causing the lens to revert to its flatter shape. This restores the extended focal length required for distant vision.

        5) Role of the Cornea

        It’s important to note that while the crystalline lens contributes significantly to accommodation, the cornea also plays a vital role. However, unlike the lens, the cornea’s curvature remains constant during this process.

        The process of accommodation in the eye is a finely orchestrated dance between the ciliary muscles and the crystalline lens. Together, they ensure that you can shift your focus from distant vistas to up-close details, allowing clear and adaptable vision.

        When we grow old, our lens will turn hard. Our accommodation ability will decrease and it will get more and more difficult to focus. This defect is called presbyopia.


        Why Does the Eye Need to Accommodate?

        The ciliary muscles, responsible for accommodation of the eye, are usually at rest. When at rest, parallel light rays that form distant objects converge onto the retina, giving you a sharp and clear view of the object.

        If the eye were to remain in such a state of rest and an object placed nearer to it, the light rays would converge behind the retina. But then, since the sharp image is behind the retina, our brain will only detect a blurry image of the closer object.

        Therefore, in order to bring that image of the closer object back into focus, the eye performs the process of accommodation.


        Types of Accommodative Dysfunctions

        A group of eye conditions collectively known as accommodative dysfunctions, can lead to challenges in focusing, eye strain, and discomfort.

        Explore the types of accommodative dysfunctions, their distinct characteristics, and the impact they can have on vision:

        1) Accommodative Infacility

        Infacility is characterised by difficulties in smoothly transitioning between near and far vision. This condition can lead to eye strain, blurred vision, and reduced focus flexibility.

        2) Accommodative Insufficiency

        In cases of accommodative insufficiency, the eyes struggle to maintain focus, especially when looking at near objects for extended periods. Individuals may experience difficulty reading or working on tasks that require sustained close-up vision.

        3) Accommodative Excess

        Accommodative excess occurs when the eyes over-focus on near objects, making it challenging to shift focus to distant objects. This can lead to eye strain, blurred vision, and discomfort when trying to see things at a distance.

        4) Accommodative Spasm (Accommodative Cramp)

        Accommodative spasm involves a sudden, involuntary contraction of the ciliary muscles, which control the shape of the eye’s lens. This can result in blurred vision and difficulty adjusting focus. It may be temporary or chronic.

        5) Accommodative Paresis (Accommodative Insufficiency)

        Accommodative paresis is defined as a total loss of accommodation, in either one, or both eyes. The affected eye is unable to focus properly on an object.

        6) Accommodative Vergence

        This condition involves issues with the coordination of eye movements when adjusting focus. Individuals with accommodative vergence may experience double vision or eye strain.

        Each type of accommodative dysfunction has its own set of symptoms and challenges, but they all involve difficulties in the eye’s ability to adjust focus effectively.

        If you suspect you may have an accommodative dysfunction, consulting with an eye care professional is essential. They can diagnose the specific issue and recommend suitable treatments, which may include vision therapy, prescription lenses, or lifestyle adjustments.


        Symptoms of Accommodative Infacility

        Symptoms of accommodative infacility can vary from person to person, but they typically involve difficulties with focusing the eyes on near objects and transitioning between near and distant vision. Some common symptoms include:

        Blurry Vision

        Individuals with accommodative infacility often experience blurred vision, especially when trying to read or view objects up close.

        Eye Strain

        Prolonged periods of reading or performing tasks that require near vision can lead to eye strain. This can manifest as discomfort, fatigue, or aching around the eyes.


        Eye strain associated with accommodative infacility can sometimes lead to headaches, particularly around the forehead or temples.

        Difficulty Shifting Focus

        People with this condition may find it challenging to quickly shift their focus from near to distant objects or vice versa. This can impact activities like driving, where rapid changes in focus are necessary.

        Loss of Concentration

        Accommodative infacility can make it challenging to concentrate on tasks that involve frequent changes in focus, such as reading and computer work.

        Slow Reading Speed

        Some individuals may notice that their reading speed is slower than expected due to the need for extra time to adjust focus.

        Double Vision

        In some cases, accommodative infacility can lead to double vision or seeing multiple images of the same object.

        It’s important to note that these symptoms may not always be exclusive to accommodative infacility and can overlap with other vision-related issues.

        If you experience persistent vision problems or any of these symptoms, it’s advisable to consult an eye care professional as soon as possible for a comprehensive evaluation and diagnosis. They can provide personalised guidance and recommend appropriate treatments or vision therapies to address these symptoms sooner rather than later, before symptoms get worse or complications arise.


        Treatment for Accommodative Infacility

        Accommodative Infacility Exercises

        Accommodative infacility exercises are vision therapy techniques designed to enhance the eye’s ability to adjust focus smoothly and efficiently. These exercises are often recommended for individuals experiencing eye strain or difficulties with tasks like reading or computer work.

        1) One common exercise involves focusing on a near object and then quickly shifting focus to a distant one, repeating this process to improve the speed of accommodation.

        2) Another technique may involve tracking moving objects to enhance convergence and divergence abilities.

        Vision therapy, often administered by optometrists specialising in binocular vision, is tailored to an individual’s specific needs. To determine the most suitable treatment approach, a consultation with an eye care professional is essential.

        Relation to Laser Eye Surgery

        For individuals with accommodative infacility, LASIK (Laser-Assisted In Situ Keratomileusis), a type of refractive surgery, can provide an immediate and long lasting solution. Refractive surgery is used to correct eyesight and restore near-perfect vision. LASIK is a surgical technique that corrects a person’s vision, reducing the need for spectacles or contact lenses. Known as Laser Assisted in Situ Keratomileusis or LASIK, the surgery involves changing the shape of the cornea.

        Refractive surgery primarily targets refractive errors and may not directly treat accommodative infacility. However, by improving visual clarity, it can reduce eye strain associated with accommodative difficulties, especially during close-up tasks.

        Refractive surgery can also be used to treat presbyopia. Monovision or laser blended vision is used to provide the patient with good vision for both near and distance. It is a very effective way of combating the loss of accommodation in later life.



        To sum up the main points on this page:

        • Accommodation occurs when the eye automatically adjusts its focus for short vision.
        • During accommodation, the ciliary muscles contract, the supporting ligaments relax, and crystalline lens of your eye becomes thicker — focusing your vision for nearby objects.
        • Several types of accommodative dysfunction can be remedied through at-home vision therapy designed to improve the overall accommodative function of the eyes.
        • LASIK can be a lasting solution for those with refractive errors contributing to accommodative dysfunction.
        • Consult with an eye care specialist for a comprehensive assessment to guide you toward the most effective treatment plan for your specific condition.

        If you’d like to know more about your visual condition or what treatment options are available for you, call and speak to our specialist team here. They will provide you with personalised advice to best manage your vision.



        What is accommodation of the eye?
        Accommodation of the eye refers to the eye’s ability to adjust its focus to see objects clearly at different distances. This is achieved by changing the shape and curvature of the eye’s natural lens to bring images into sharp focus on the retina.
        What is the accommodation range of the human eye?
        The human eye typically has an accommodation range of approximately 4 diopters, allowing it to focus on objects as close as about 25 centimeters (10 inches) to objects in the distance, such as faraway landscapes or stars in the night sky.
        What is accommodation eye lens?
        The accommodation eye lens, often simply referred to as the eye’s lens, is a flexible, transparent structure located behind the iris. It plays a crucial role in the eye’s accommodation process by changing its shape to adjust the focal point, allowing us to see objects at varying distances with clarity.
        Book a Consultation
        The AccuVision team is not call centre based. We will use the information you provide here to direct your enquiry appropriately and your information is not used for unsolicited marketing or shared with third parties.

          Our dedicated and friendly staff is here to assist you with any questions to ensure you're on the fast track to visual freedom.

          Fill out the form below so we know the best time to reach you or simply call us on0330 123 2020WhatsApp

          The information you have provided may be held on our database. It will not be sold to any third party. Our privacy policy which we are obliged to give you under the GDPR is available here.

          Invest in your visual future
          Wavefront LASIK Vision Correction
          Summer Offer!
          JUST£1200*per eye
          *Usual price £1800 per eye | *T’s & C’s apply
          Fill in the contact form or call us today to arrange a complimentary screening consultation. Quote “Summer Offer!” when making your enquiry.
          *See T’s & C’s below.

            I agree with terms of use and privacy policy

            The information you have provided may be held on our database. It will not be sold to any third party. Our privacy policy which we are obliged to give you under the GDPR is available here.

            Terms & Conditions
            Offer price of £1200 per eye is valid for:
            • WaveFront Optimised Surgery for both eyes. Offer does not apply to a single eye treatment.
            • Myopic prescriptions under -3.50 dioptres only. Prescriptions with other additional conditions/variations may not be eligible and are subject to a detailed evaluation.
            • Prescriptions outside the eligible range are always competitively priced.
            • This offer cannot be used in conjunction with any other offer.
            • There are no cash alternatives to this offer.
            • All eye surgical procedures carry a level of risk including not obtaining the desired outcomes through to varying levels of visual loss. Your eye surgeon will discuss the risks and benefits including ones specific to your circumstances at the time of your preoperative consultation.
            • AccuVision reserve the right to change or withdraw this offer.