Hyperopic Defocus Blur
Author: Corrina McElduff
Optometrist & Advisory Committee member
What is hyperoic defocus blur and how does it help manage myopia?
Hyperopic defocus refers to deliberately introducing out-of-focus images on the peripheral retina while maintaining clear vision on the central retina. It is used as a technique in myopia management to slow down the lengthening of the eye which is also known as axial length.
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The mechanism behind how hyperopic defocus works is not yet fully understood, but there are a few proposed theories. One evidenced theory suggests that when the peripheral retina experiences defocused or blurred images, it sends signals to the eye to slow down its growth in an attempt to achieve clear vision. This feedback mechanism helps regulate the elongation of the eyeball, which is a characteristic of myopia.
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By using specific optical designs in contact lenses or spectacle lenses, hyperopic defocus or blur can be created. These lenses allow clear central vision while introducing a controlled blur in the peripheral vision. When worn consistently, this technique has shown promising results in slowing down axial length growth and managing myopia progression in children.
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It's important to note that the effectiveness of hyperopic defocus and its suitability for individuals can vary. Professional consultation with an eye care specialist is necessary to determine the most appropriate myopia management strategies for each individual.
TL;DR Key Points
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Hyperopic defocus blur is a technique in myopia management to slow down myopia progression.
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Induced blur: Peripheral vision intentionally blurred while maintaining central clarity.
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Stimulating optical signals: Blurred images trigger feedback mechanism in the peripheral retina.
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Impact on eye growth: Believed to influence eyeball elongation and myopia progression.
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Implementation and consultation: Hyperopic defocus blur is used in specialised myopia soft contact lenses and in glasses
FOCUS
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Several studies have shown a correlation between the amount of time spent outdoors and a reduced risk of developing myopia or slower progression of existing myopia. Spending more time in natural daylight and engaging in outdoor activities has been associated with a protective effect against the development and progression of myopia in children. This suggests that environmental factors may play a role in managing myopia.
What does hyperopic blur look like?
Imagine looking through a pair of glasses or contact lenses that provide clear vision in the center of your field of view and defocus in the peripheral areas. This means that objects in your peripheral vision appear slightly blurry or out of focus while maintaining clear vision in the centre, which is actually typical of how we all see. This can seem slightly strange when we describe hyperopic blur but children and young adults that wear these specific glasses and contact lenses generally have no issues with seeing and completing everyday tasks.
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The purpose of creating this intentional blur is to stimulate specific optical signals in the peripheral retina. It is believed that these signals trigger a feedback mechanism that influences the growth and elongation of the eyeball. By providing the peripheral retina with defocused images, it may help slow down the elongation of the eye and the progression of myopia.
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The actual implementation of hyperopic defocus or blur can vary and may involve specialized contact lenses, spectacle lenses, or other optical devices. These lenses are designed to manipulate the incoming light in a way that induces the desired blur in the peripheral retina while maintaining clear vision in the central retina.
