In a world where screens dictate our lives, headaches have become all too common. They are most often attributed to stress or digital strain. In this blog, we discover often-overlooked relationship between headaches and refractive errors.
What is Refractive Error?
Refractive error is a common vision problem that occurs when the eye is unable to focus light properly onto the retina, leading to blurred or distorted vision. This happens because the shape of the eye or the eye’s focusing ability is not ideal, causing light to be improperly focused in front of or behind the retina, rather than directly on it. The retina is the light-sensitive tissue at the back of the eye that sends visual signals to the brain.
Types of Refractive Errors
There are several types of refractive errors:
1. Myopia (Nearsightedness): In myopia, distant objects appear blurry, while close-up objects can be seen more clearly. This occurs when the eyeball is too long or the cornea (the clear front surface of the eye) is too curved. Light entering the eye focuses in front of the retina instead of on it.
2. Hyperopia (Farsightedness): Hyperopia is the opposite of myopia. In hyperopia, close-up objects may be blurry, while distant objects are seen more clearly. It happens when the eyeball is too short or the cornea has too little curvature, causing light to focus behind the retina.
3. Astigmatism: Astigmatism occurs when the cornea or lens of the eye is unevenly curved, causing blurred vision at both near and far distances. It can accompany myopia or hyperopia.
4. Presbyopia: Presbyopia is an age-related condition that affects near vision. As people age, the natural lens of the eye becomes less flexible, making it harder to focus on close-up objects. It is not a refractive error in the traditional sense, but it is a common vision problem that usually begins around the age of 40.
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Connection Between Refractive Errors and Headaches
Refractive errors and headaches have not been proven to be causally related. Due to the high incidence of both disorders in the general population (12.5% of the general population would have both at the same time), several writers assumed a coincidental correlation rather than a cause-and-effect relationship.
In individuals with untreated refractive problems, headaches are more frequent, according to other studies. Researchers in this article examined the traits of headaches associated with refractive errors and looked for relationship between those characteristics and specific risk variables.
Risk factors Contributing to Headache
According to analysis, HARE (Headache Associated with Refractive Errors) was statistically significant with:
- Extended screen time,
- prolonged reading,
- the combined nature of ametropia,
- as well as several specific forms of ametropia, including moderate myopia, moderate and severe hyperopia, moderate astigmatism, convergence insufficiency, and esophoria.
The complex nature of ametropia, moderate hyperopia, moderate astigmatism, and prolonged exposure to the screen were found to be four independent risk factors that are associated with the presence of headaches.
Researchers discovered that the headaches in their patients were primarily chronic, progressive, daily, and predominately in the second part of the day. They were accompanied by additional ophthalmological symptoms including tearing and tingling (36% of cases).
Asthenopia – Headache due to Eye Strain
Asthenopia, a word for headache brought on by eye strain, is included in HARE. Ametropia, extraocular muscle imbalance, poor reading or working habits, and surroundings all contribute to asthenopia.
Numerous symptoms are included, such as lacrimation, itchiness, redness, eye pain, orbital pain, headache (particularly frontal), fluctuating vision, impaired vision, or discomfort when reading.
The diseases may be infrequent and minor, but they can also be seriously incapacitating and have an adverse impact on professional performance due to sluggish knowledge integration, poor memorization, reading and comprehending problems, and a deterioration in intellectual ability.
Astigmatism, Anisometropia, and Hyperopia
Numerous risk factors are considered to contribute to HARE.
Most studies agree that astigmatism and mild anisometropia are the most problematic, perhaps because of the visual blur they generate.
Hyperopia could also cause headaches by means of sustained accommodative effort. Myopia induces contraction of the scalp and periorbital muscles to obtain the pinhole effect by squinting and narrowing the palpebral fissures.
Treatment of Headache
More than 50% of ophthalmologists are motivated to provide an optical correction when there is a headache. In fact, both primary headaches and HARE are greatly improved by adequate refractive error correction.
If mild heterophoria, accommodative asthenopia, or convergence insufficiency are present, orthoptic treatment is required to sustain the functional improvement.
Along with sufficient eye correction, a healthy lifestyle is also essential. It is focused on limiting the amount of time spent working in close proximity, distributing and varying the tasks, respecting scheduled breaks (five minutes every hour), blinking frequently to prevent eye dryness, and maintaining proper posture to prevent generalized muscle tension by adjusting workstation ergonomics and screen lighting.
According to a research by Mehboob et al., 62.5% of patients reported relief from their headaches following optical correction in four weeks, 75 percent in eight weeks, and in 25 percent of instances, the headache remained after the correction. In this article, researches found that headaches improved in every single case. It occurred in 43 individuals and after one month, there was no factor affecting its development.
A thorough ophthalmological examination and an orthoptic evaluation are necessary for a valid evaluation of HARE. Patients with this illness may experience a reduction in their quality of life. Thus it is important to find an effective therapy that is focused on risk factor management, such as leading a healthy lifestyle and receiving proper refractive error correction. If there are oculomotor problems, therapy can enhance the long-term outcomes.
Risk factors include extended screen time, prolonged reading, the combined nature of ametropia, as well as several specific forms of ametropia, including moderate myopia, moderate and severe hyperopia, moderate astigmatism, convergence insufficiency, and esophoria.
Firstly, it can be greatly improved by adequate refractive error correction. If mild heterophoria, accommodative asthenopia, or convergence insufficiency are present, orthoptic treatment is required to sustain the functional improvement.
Source: Lajmi, H., Choura, R., ben Achour, B., Doukh, M., Amin, Z., & Hmaied, W. (2021). Headache associated with refractive errors: Characteristics and risk factors. Revue Neurologique, 177(8), 947–954. https://doi.org/10.1016/j.neurol.2020.10.008