Learn about nearsightedness (myopia) - its causes, symptoms, and treatment options. Find valuable information at Meri Sehat.

Nearsightedness (Myopia)

Medilink Consultant clinic

Online Consultation

ZAKA CLINIC GULBERG LAHORE

Saad Ullah Siddiqui

Overview

Nearsightedness, also known as myopia, is characterized by an impaired long-distance vision. Myopia is due to a refractive error that causes far away objects to appear blurry, while near objects look clear. 
&nbsp;

Myopia is the main root of eyesight loss worldwide, with a rising prevalence<a href="#accordion">[1]</a>.&nbsp;According to the American Optometric Association, approximately 30% of Americans suffer from nearsightedness<a href="#accordion">[10]</a>. However, studies have shown East Asian and Southeast Asian countries to have the highest prevalence rates compared to the rest of the world<a href="#accordion">[3]</a>.

Although myopia can affect adults, it is more common in children aged 6 to 13 years. Asians have the highest prevalence (18.5%), followed by Hispanics (13.2%), African Americans (6.6%), and Caucasians (4.4%)<a href="#accordion">[2]</a>. In the United Kingdom, 49% of adults aged 44 and up are affected by myopia<a href="#accordion">[2]</a>.

Myopia is the most frequently occurring refractive error in children and teenagers. While a significant number of myopic children will develop only mild to moderate myopia, a few will speedily advance to severe myopia. According to ophthalmologists, &quot;near&quot; activities like reading a book or using mobile phones and laptops, increase the likelihood of children developing nearsightedness.

Myopia is a prevalent condition, generally treatable with eyeglasses, contacts, or surgical procedures. Early treatment of myopia in childhood can aid in preventing its advancement and the adverse consequences of poor eyesight. 
&nbsp;

Nearsightedness or myopia can be classified in various ways. Based on the etiology, it can be classified into axial myopia and refractive myopia.

<ul>
	<li>Axial Myopia - This results from an increase in the axial length of the eye.</li>
	<li>Refractive Myopia - This results from changes in the structure or location of the cornea and/or lens causing light rays to bend incorrectly. 
	&nbsp;</li>
</ul>

Myopia can also be classified based on clinical appearance<a href="#accordion">[12]</a>.

<ul>
	<li>Simple Myopia - Also called non-pathological myopia, it is a common type of nearsightedness. Although the refractive power of the eye is within normal limits, it does not correlate with the axial length. Both environmental and genetic factors play a role in its development. The onset of the disease usually occurs during childhood or adolescence and progresses gradually throughout the adolescent period.</li>
	<li>Degenerative Myopia - Also called pathological or malignant myopia, this type of nearsightedness results from a rapidly growing eyeball. The elongated eyeball stretches the tissues of the eyes thinner than usual. Thus, increasing the risk of macular degeneration, retinal detachment, retinal atrophy, and other retinal problems. An axial length of more than 26.5mm or refractive error of more than 6 is defined as pathologic myopia. Pathologic myopia tends to worsen over time and is the main cause of visual impairment. Gray spots in the visual field, loss of central vision, distortion of straight lines, and difficulty recognizing faces are common signs and symptoms of degenerative myopia.</li>
	<li>Nocturnal Myopia - Also known as twilight myopia or night myopia, it is characterized by difficulty seeing in low light areas. However, daytime vision is normal. This type of myopia is more common in younger people than in the elderly.</li>
	<li>Pseudomyopia - The spasm of ciliary muscle cause blurring of distance vision.</li>
	<li>Induced Myopia - Also called acquired myopia, it results from conditions such as high blood glucose levels, exposure to chemicals, nuclear sclerosis, cataracts, etc. 
	&nbsp;</li>
</ul>

Signs and Symptoms

Nearsightedness is characterized by fuzzy or blurred distant vision. It can make it difficult to watch TV from across the room or tell time from a wall clock that is a bit far. However, depending on the cause and severity, other symptoms can also appear. These include:

<ul>
	<li>Headaches</li>
	<li>Eye strain</li>
	<li>Eye fatigue</li>
	<li>Squinting</li>
	<li>Weariness when driving, participating in sports, or looking farther than a few feet away. 
	&nbsp;</li>
</ul>

<h5>In Children</h5>

Myopic children and teenagers may have difficulty reading from the board or screen projections in their classroom. Younger children are usually unable to communicate vision problems and may exhibit behaviors indicating difficulty seeing. These include: 
&nbsp;

<ul>
	<li>Squinting</li>
	<li>Unaware of distant objects</li>
	<li>Blinking frequently</li>
	<li>Rubbing eyes constantly</li>
	<li>Watching the television from a very close distance</li>
</ul>

&nbsp;

<h5>In Adults</h5>

Adults who have myopia may experience problems reading street signs or store signs. Even if some individuals see clearly in daylight, they may have a fuzzy vision in dim light, such as when driving at night. This is called night myopia.

Note: Get emergency medical attention if you have any of the symptoms given below:

<ul>
	<li>The abrupt appearance of several floaters (specks or lines that appear to drift across your field of vision).</li>
	<li>Light flashes in one or both eyes</li>
	<li>A curtain-like gray shadow that covers all or a bit of your field of vision.</li>
	<li>A shadow in your outermost or side vision (peripheral vision). 
	&nbsp;</li>
</ul>

These are warning symptoms of retinal detachment. It is a medical emergency that requires immediate treatment. Notable nearsightedness is linked to a higher risk of retinal detachment. 
&nbsp;

Causes

Each eye has two regions that focus the light and form an image:

<ul>
	<li>The cornea: The front, transparent surface of the eye that resembles a dome shape.</li>
	<li>Lens: A clear, curved structure present at the front of the eye. 
	&nbsp;</li>
</ul>

If the eye is excessively curved, then the light cannot focus accurately. As a result, images get focused in front of the retina, instead of being focused directly on the retina, leading to blurry vision. This condition is known as a refractive error.

High myopia is a serious type of nearsightedness where the eyeball becomes too long, making it hard to see far away things. It can also increase the risk of other eye problems like a detached retina, cataracts, and glaucoma.

Degenerative myopia is a rare and severe type of nearsightedness that usually runs in families. It happens when the eyeball grows too long too quickly, leading to severe nearsightedness in the teenage or early adult years. This type of myopia can get worse as one gets older and can also increase the risk of other eye problems like a detached retina, abnormal blood vessel growth, and glaucoma. 
&nbsp;

There are currently no screening tests for nearsightedness. However, the American Optometric Association (AOA) recommends conducting eye exams every two years for school-aged children. Whereas, children that need corrective lenses or eyeglasses are recommended yearly exams. A Snellen chart or a pinhole test may be used to test eyesight. 
&nbsp;

The following are the recommended vision screenings for children:

<ul>
	<li>Ages 3-5: At least once</li>
	<li>Ages 5-6: Once before kindergarten</li>
	<li>Others are recommended yearly eye exams till the end of high school 
	&nbsp;</li>
</ul>

In adults with no known vision problems or eye disease, the following schedule is recommended:

<ul>
	<li>Ages 20-29: At least once</li>
	<li>Ages 30-39: At least twice</li>
	<li>Ages 40-54: Every 2 to 4 years</li>
	<li>Ages 55-64: Every 1 to 3 years</li>
	<li>Ages 65 and above: Every 1 to 2 years 
	&nbsp;</li>
</ul>

However, adults with risk factors or myopia are advised to have more frequent eye exams. 
&nbsp;

Diagnosis

Doctors can detect myopia during a routine eye exam. These examinations track both vision and eye health. An eye specialist can perform various tests to determine whether or not an individual is myopic.

People with nearsightedness or another eye condition should undergo routine eye examinations to observe their prescription and test for severe eye conditions.

The following factors determine the frequency of eye exams: 
&nbsp;

<ul>
	<li>Age</li>
	<li>Medical history</li>
	<li>Medications used</li>
	<li>Eye health 
	&nbsp;</li>
</ul>

A comprehensive eye exam may include the tests given below:

Medical History - The eye specialist will inquire about the patient&rsquo;s medical history and any medicine they are currently taking. 
&nbsp;

Visual Acuity Test - A visual acuity test determines the sharpness of vision at a distance. While closing one eye, the person is asked to read an eye chart with different-sized alphabets or symbols. The test is repeated for the other eye. Separate charts are used for young children. 
&nbsp;

Phoropter Test - This test involves reading an eye chart while looking through a device with various lenses to assist in detecting an accurate prescription to correct eyesight issues. 
&nbsp;

Refraction Test - To determine a refraction error, the eye specialist will have the person look through a specific machine with different lenses. If necessary, this test can be used to identify the individual&rsquo;s lens prescription. 
&nbsp;

Retinoscopy - This is an important tool for determining refractive errors. In clinical practice, two kinds of retinoscopy are used - spot and streak. The test involves shining light through a retinoscope into the pupil and then observing the reflection off of the retina. A streak or spot of light is moved across the pupil as the doctor observes the focal length. This is the degree at which the retinoscope&rsquo;s light is reflected off the retina. In people with myopia greater than 1.5 D, the reflected light from the retina moves in the opposite direction as the projected light. Whereas, in people with myopia less than 1.5 D, the reflected light moves in a similar direction as the streak light.

The optometrist may also hold up lenses with varying prescriptions in front of the eye to identify which works best to correct the patient&rsquo;s refractive error. 
&nbsp;

Pupil Exam - The pupil exam tests the reaction of the patient&rsquo;s pupils to bright light. Normally, pupils shrink in response to bright light. Any other reaction is seen as a cause for concern. 
&nbsp;

Peripheral Vision Test - This involves testing the patient&rsquo;s peripheral, or side, vision to assess the patient for glaucoma. The eye disease leads to a loss of side vision and can progress to blindness if left untreated. 
&nbsp;

Eye Movement Test - The eye movement test checks the health of the eye muscles. These muscles are in charge of eye movement. 
&nbsp;

Eye Pressure Test - The eye pressure test measures the pressure within the eyes. In glaucoma, patients may have high eye pressure. 
&nbsp;

Eye Health and Structure Exam - The eye specialist will examine the cornea for any damage or signs of cataracts. 
&nbsp;

Autorefractometer (Optometer) - Myopia detection has become more convenient and straightforward since the introduction of Optometer. Due to its high accuracy, the computer-controlled machine is more commonly used for screening patients with myopia. Moreover, it is highly effective in checking for myopia in children as the test can take as short as 5 minutes. The machine directs infrared light with a wavelength of 800 to 900 nm into the eye, and doctors use reflected light to compute refractive errors. 
&nbsp;

Retina And Optic Nerve Exam - The test involves dilating the patient&#39;s eye to widen the pupil and make it easier for the doctor to assess the retina and optic nerve for damage. Patients may require help getting home after the appointment as their eyes may be sensitive to light for a few hours after the test, making it difficult to drive. 
&nbsp;

Corneal Topography - Corneal topography is essential in identifying myopia-related corneal disorders. It is critical for pointing out myopic patients who are candidates for laser refractive surgery. Corneal examination displays the biomechanical integrity of the cornea, assisting surgeons in planning accurate management and providing spectacle-free vision. 
&nbsp;

Slit-lamp Examination - A slit lamp examination of the eye gives complete information about the:

<ul>
	<li>Corneal thickness</li>
	<li>Anterior chamber depth</li>
	<li>Iridocorneal angle</li>
	<li>Lenticular thickness</li>
	<li>Optic disc</li>
	<li>Macula 
	&nbsp;</li>
</ul>

Treatment

In nearsightedness, the aim of treatment is to improve vision, either with the help of corrective lenses or refractive surgery.

With nearsightedness, the prescription for glasses or contact lenses is a negative number, for example, -2.00. The greater the number, the more powerful the lenses will be. The prescription aids the eye in focusing light on the retina, improving distance vision.

Nearsightedness management also includes routine screening for problems, for example, glaucoma, cataracts, and retinal detachment.

Doctors can use the following techniques to treat nearsightedness: 
&nbsp;

<h5>Corrective Lenses</h5>

These include eyeglasses and contact lenses. By shifting the focus of light as it enters the eye, these devices compensate for the curved corneas or increased length of the eye. Individuals of all ages can wear eyeglasses.

The strength of the prescription will be based on how far the patient can see clearly.

Doctors may advise wearing the corrective lenses all the time or only for specific activities, for example, driving.

Contact lenses are small plastic discs that are placed against the cornea. A single contact lens can correct more than one refractive error. There are various materials and maintenance requirements. They typically provide a larger field of corrected vision than glasses. However, not everyone can wear contact lenses as they can cause irritation in some people. 
&nbsp;

Some myopic children may only need glasses to play ball, watch a movie, or read the chalkboard. A few individuals may require to wear glasses all the time to see clearly. A single-vision lens will improve distance vision. People over 40 with myopia may need a bifocal or progressive lens to see objects clearly both nearby and far away. 
&nbsp;

<h5>Refractive Surgery</h5>

Refractive surgery is a permanent method of correcting nearsightedness. The procedure, also known as laser eye surgery, reshapes the cornea to direct light on the retina. Doctors only perform the procedure in adults.

Refractive surgeries have transformed myopia management by removing the need for spectacles and increasing the field of vision. However, post-surgery, eyeglasses may be required some of the time. 
&nbsp;

1. Laser-Assisted In Situ Keratomileusis (LASIK)

It is the most commonly used procedure for correcting nearsightedness. The eye surgeon will insert a thin, hinged flap into the cornea during this procedure. They then use a laser to excise corneal tissue, flattening its domed shape.

LASIK surgery generally results in faster recovery and less pain than other corneal surgical procedures. The following are the most common short-term side effects of LASIK:

&nbsp;

<ul>
	<li>Fuzzy or blurred vision.</li>
	<li>Problems with night vision.</li>
	<li>Itchy or dry eyes.</li>
	<li>Halos or glares.</li>
	<li>Sensitivity to light.</li>
	<li>Discomfort or ache.</li>
	<li>Tiny pink or red patches on the white part of the eye.</li>
</ul>

These complications usually resolve themselves within six months to a year. In rare instances, a few of these side effects may be long-lasting.

&nbsp;

2. Laser-Assisted Subepithelial Keratectomy (LASEK)

The eye specialist only makes an ultrathin flap in the outer protective cover of the cornea (epithelium). They then reshape the cornea with a laser, flattening its curve, before replacing the epithelium.

&nbsp;

3. Photorefractive Keratectomy (PRK)

It&#39;s a laser eye surgery used to treat mild to moderate myopia. PRK procedure is comparable to LASEK, except for the fact that the medical professional entirely excises the epithelium before reshaping the cornea with a laser.

A short-term, protective contact lens covers the cornea until the epithelium heals naturally and conforms to the new shape of the cornea. PRK is recommended for individuals with thinner or rougher corneas because it disrupts less corneal tissue than similar LASIK surgery.

&nbsp;

4. Small Incision Lenticule Extraction (SMILE)

In this technique, there is no flap or epithelium removal by the surgeon. Alternatively, the surgeon uses a laser to cut a tiny disk-shaped piece of the cornea (lenticule), which the doctor then excises by a tiny corneal slit.

&nbsp;

5. Phakic Intraocular Lenses 

These lenses are a viable option for individuals with high myopia or corneas that are too thin for PRK or LASIK. Doctors implant the phakic intraocular lenses inside the eye, directly in front of the natural lens.

&nbsp;

6. Intraocular Lens Implant 

It enables the ophthalmologist to surgically replace the natural eye lens with a new lens. The doctor performs the procedure before cataract forms.

&nbsp;

7. Vision Therapy 

Vision therapy is an alternative if spasms of the eye muscles are causing myopia. Eye exercises can help to strengthen the muscles and enhance one&rsquo;s focus.

&nbsp;

8. Ortho-k or CRT

Corneal reshaping therapy is also known as orthokeratology. It entails modifying the shape of the cornea with particular lenses for a short period. 
&nbsp;

&nbsp;A few individuals with mild myopia may be candidates for short-term corneal refractive contact lenses that they can wear to bed to briefly reshape the cornea, long enough to see for everyday activities. 
&nbsp;

<h5>Eye Drops</h5>

Doctors frequently use atropine drops to dilate the pupil of the eye, either as part of an eye examination or prior and post-eye surgery. Eye specialists may use low-dose atropine to aid in slowing down the advancement of myopia in children

&nbsp;

<h5>EVO Implantable Collamer Lens (ICL)</h5>

Doctors implant a contact lens made of soft, polymeric materials into the eye, between the natural lens and the iris via a microscopic incision. It aids in light refraction on the retina, resulting in clearer vision. In a few cases, the eye specialist may recommend cataract or clear lens replacement surgery. 
&nbsp;

Numerous issues, ranging in severity from minor to severe, are linked to nearsightedness, including: 
&nbsp;

<ul>
	<li>Poor School Experiences - Myopia and other vision issues can cause delays in reading development and other academic skills in children, as well as social interaction issues and low self-esteem.</li>
</ul>

<ul>
	<li>Reduced Quality Of Life - Untreated nearsightedness might make it difficult for people to enjoy activities or perform daily tasks.</li>
	<li>Eyestrain - If left untreated, nearsightedness may result in headaches and eye strain.</li>
	<li>Impaired Safety - If a person has an untreated visual issue, both their safety and that of others may be in danger, especially if using heavy machinery or driving a car.</li>
	<li>Other Eye Problems - Severe type of myopia can increase the risk of eye disorders like <a href="https://merisehat.pk/disease/cataract">cataracts</a>, <a href="https://merisehat.pk/disease/glaucoma">glaucoma</a>, and retinal detachment. 
	&nbsp;</li>
</ul>

Nearsightedness may be more likely to develop if particular risk factors exist, such as the following: 
&nbsp;

<ul>
	<li>Age - Myopia commonly develops between the ages of 6 and 24 years. It can worsen with age until the person&rsquo;s early 20s.</li>
	<li>Genetics - The tendency to be nearsighted runs through families. Children with one or both parents with nearsightedness are at a higher risk of developing myopia.&nbsp;</li>
	<li>Prolonged Close-up Activities - Long periods of reading or other close-up work are linked to a higher risk of nearsightedness.</li>
	<li>Diabetes - Certain health conditions, such as diabetes, can increase the risk of nearsightedness in adults.</li>
	<li>Screen Time - According to research, children who overuse computers or other smart gadgets for extended periods of time have a higher chance of becoming nearsighted. A study conducted in Delhi found that children who spent 7 hours or more using screens had triple the risk of developing myopia<a href="#accordion">[11]</a>.</li>
	<li>Environmental Conditions - A lack of outdoor activity may raise the chance of developing nearsightedness. 
	&nbsp;</li>
</ul>

The following is a list of potential measures to prevent or manage myopia: 
&nbsp;

<ol>
	<li>&nbsp;Visual Correction - Many parents worry that if a doctor recommends glasses to be worn most of the time, their child will become reliant on them or that the eyeglasses may increase their child&#39;s vision problems. Some parents might believe it is best to leave the condition alone. However, studies suggest that delaying treating a child&#39;s nearsightedness can potentially make it worse. Additionally, it was long believed that under correcting nearsightedness could slow growth. Currently, it is believed that under-correction is linked to a faster rate of myopia advancement. 
	&nbsp;</li>
	<li>&nbsp;Outdoor Activities - A number of significant studies have demonstrated that spending time outside can prevent the course of nearsightedness or perhaps delay its start. Although further research is needed, spending time outside seems to at least be a significant risk factor. 
	&nbsp;</li>
	<li>&nbsp;Low-Dose Atropine - Myopia progression has been demonstrated to be significantly slowed down by atropine ophthalmic solution. However, the pace at which the eyeball lengthens is not slowed. Nevertheless, numerous investigations (ranging from 0.01% to 1% doses) have demonstrated a high percentage of effectiveness<a href="#accordion">[6]</a>. Daily eye drops containing atropine are administered, typically before night. The precise mechanism is unknown. Atropine has been found in studies to be safe at low doses, but at high quantities, it can have some unpleasant side effects, like sensitivity to light (photophobia). 
	&nbsp;</li>
	<li>&nbsp;Orthokeratology - Wearing special contact lenses at night is part of orthokeratology, also known as corneal refractive treatment (CRT) or corneal reshaping. They alter the cornea&#39;s shape by flattening the center while steepening the margins, refocusing incoming peripheral light in front of the retina instead of behind it, known as peripheral myopic defocus and peripheral hyperopic defocus, respectively. This seems to slow the eyeball&#39;s elongation, which inhibits the development of myopia. Even if the lenses are only worn at night, they continue to have an impact the next day. 
	&nbsp;</li>
	<li>&nbsp;Multifocal Soft Contact Lenses - A 2014 study in Hong Kong children found that children wearing soft multifocal lenses saw 25% decrease in disease progression and 31% less axial elongation over two years than those wearing single-vision lenses<a href="#accordion">[7]</a>. According to doctors, it operates similarly to orthokeratology. The &quot;center-distance&quot; multifocal focus light directly on the central retina and in front of the peripheral retina, giving users clear vision. 
	&nbsp;</li>
	<li>&nbsp;Avoid Reading in Low Light - Reading in low light can strain the light which may result in vision problems, including nearsightedness. Therefore, it is advised to only read books, magazines, and other printed materials in well-lit, well-ventilated environments. 
	&nbsp;</li>
	<li>&nbsp;Eye Yoga&nbsp;- Exercises for eye yoga are intended to ease close-up work-related eye strain. Additionally, they can increase blood flow to the area surrounding your eyes and prevent them from being overly dry.<a href="#accordion">[8]</a> 
	&nbsp;</li>
</ol>

Other common measures that can protect one&rsquo;s vision include:

<ul>
	<li>Limiting screen time</li>
	<li>Spending more time outdoors</li>
	<li>Taking a 20-second break every 20 minutes to look at an object or something 20 feet away (20-20-20 rule).</li>
	<li>Wearing corrective lenses or eyeglasses as per the doctor&rsquo;s prescription</li>
	<li>Using protective eyewear when near toxic chemicals or playing certain sports</li>
	<li>Taking frequent breaks from staring at screens</li>
	<li>Eating a healthy diet</li>
	<li>Managing health conditions, such as diabetes</li>
	<li>Regular eye exams</li>
	<li>Quitting smoking 
	&nbsp;</li>
</ul>

Sub-chronic and chronic toxicity evaluation of 7-methylxanthine: a new molecule for the treatment of myopia.<a href="#accordion">[9]</a>

Myopia (nearsightedness) is a vision disorder with a blurring of far objects, affecting millions worldwide. 7-methylxanthine (7-MX) is a molecule that is presently under clinical investigation for the treatment of myopia.

According to OECD recommendations 408 and 452, researchers have examined the sub-chronic and chronic toxicity of 7-MX with other therapeutically utilized methylxanthines, such as caffeine and theobromine. Rats were given 7-MX orally for 90 days at three separate dosages of 250, 500, and 1000 mg/kg to assess sub-chronic toxicity and for 180 days at a maximum dose of 1000 mg/kg to assess chronic toxicity.

In sub-chronic therapy, 7-MX produced no mortality and no evidence of toxicity in either group. In contrast, caffeine and theobromine-treated groups showed 10% and 40% mortality, respectively, with symptoms of toxicity. In a 180-day chronic toxicity trial with 7-MX, a comparable safety profile was seen. 
&nbsp;

Additionally, ultrasound and X-ray studies were carried out to confirm any morphological alterations in the organs; however, no changes in the size of the organs, cyst formation, fluid retention, or crystal formation were noticed. So, the prospect of using 7-MX clinically for the safe and efficient treatment of myopia may be increased by the repeated dose research of 7-MX for 180 days. 
&nbsp;

Key Points

<ul>
	<li>Myopia is the main root of eyesight loss worldwide, with a rising prevalence.</li>
	<li>Nearsightedness, or myopia, occurs due to a refractive error that causes far-away objects to appear blurry, while near objects look clear.</li>
	<li>Reading and watching television up close can exacerbate myopia, especially in young children.</li>
	<li>Myopia can be treated with contact lenses, eyeglasses, or surgery. 
	&nbsp;</li>
</ul>

[1] Fredrick DR. Myopia. Bmj. 2002;324(7347):1195–9.

[2] Subudhi P, Agarwal P. Myopia. In: StatPearls [Internet]. StatPearls Publishing; 2022.

[3] Foster PJ, and Jiang Y. Epidemiology of myopia. Eye. 2014;28(2):202–8.

[4] Lagrèze WA, Schaeffel F. Preventing myopia. Dtsch Arztebl Int. 2017;114(35–36):575.

[5] Holden B, Sankaridurg P, Smith E, Aller T, Jong M, He M. Myopia, an underrated global challenge to vision: where the current data takes us on myopia control. Eye. 2014;28(2):142–6.

[6] Gong Q, Janowski M, Luo M, Wei H, Chen B, Yang G, et al. Efficacy and Adverse Effects of Atropine in Childhood Myopia: A Meta-analysis. JAMA Ophthalmol [Internet].

[7] Lam CSY, Tang WC, Tse DY-Y, Tang YY, To CH. Defocus Incorporated Soft Contact (DISC) lens slows myopia progression in Hong Kong Chinese schoolchildren: a 2-year randomised clinical trial. Br J Ophthalmol [Internet]. 2014;98(1):40–5.

[8] Kim S-D. Effects of yogic eye exercises on eye fatigue in undergraduate nursing students. J Phys Ther Sci. 2016 Jun;28(6):1813–5.

[9] Singh H, Singh H, Sahajpal NS, Paul S, Kaur I, Jain SK. Sub-chronic and chronic toxicity evaluation of 7-methylxanthine: a new molecule for the treatment of myopia. Drug Chem Toxicol. 2022;45(3):1383–94.

[10] Myopia. AOA.org. Accessed March 7, 2023.

[11] Saxena R, Vashist P, Tandon R, Pandey RM, Bhardawaj A, Gupta V, et al. (2017) Incidence and progression of myopia and associated factors in urban school children in Delhi: The North India Myopia Study (NIM Study). PLoS ONE 12(12): e0189774.