Refractive Errors of Eye - Definition, Types, Correction, Treatment

Refractive errors (REs), like nearsightedness and farsightedness, are quite common in India. About 53% of adults have vision issues that require correction, such as glasses or contact lenses. Additionally, around 10% of adults have uncorrected vision problems. 

Nearly one in three adults struggle with uncorrected age-related vision issues, like presbyopia, which makes it hard to see things up close.

Correcting REs like nearsightedness or farsightedness in adults is usually simpler than treating other eye conditions that can lead to more severe vision loss. Read below for more information about the condition, including its types, symptoms, causes, risk factors, prevention, diagnosis, and treatment.

It is a eye disorder that cause difficulty in focusing. This happens when the refractive light rays to produce clear images on the retina due to changes in the parts of the eyes. This leads to blurry vision. If left untreated, refractive errors of the eye may lead to complete blindness. Therefore, one must not take this condition lightly. A proper eye checkup is mandatory to see clearer and live a normal life. 

It can develop at any point in time. However, different types of refractive errors may affect different age groups.

Depending on how distorted and blurry the vision is, there are four types of refractive errors, namely:

1. Nearsightedness (Myopia): In this condition, the nearby objects are easier to see, but it becomes difficult to see the distant/faraway objects. Children aged 6 to 14 are more likely to develop myopia than any other age group. 
2. Farsightedness (Hyperopia): Hyperopia is the refractive error of the eye in which the patient cannot see nearby objects properly. However, they can comfortably see objects at a distance. Most times, hyperopia affects the age group of 8 to 15 years. 
3. Age-related Farsightedness (Presbyopia): Presbyopia is one of the most common condition that affects middle-aged people and older citizens. To be more specific, it occurs in people older than 45. Presbyopia worsens over time, but it usually stops growing after 65 years of age. 
4. Astigmatism: It makes the vision distorted or blurred. It can be caused as a result of eye surgery or an eye injury. Further, it can also be a congenital eye disorder. Frequently, astigmatism has been observed to develop in children and new adults. 

Refractive error is a vision problem when light doesn't focus correctly on the retina, leading to blurred or unclear images. It causes the following symptoms:

• Blurred Vision: Trouble seeing things clearly, whether they are far away, close up, or both. This is the primary symptom of refractive error.

• Headaches: Frequent headaches, often because of squinting or straining your eyes.

• Tired Eyes: Eyes that feel tired or uncomfortable, especially after looking at screens or reading for a long time.

• Eye Irritation: Red, itchy eyes or the feeling like something is in your eye.

• Frowning and Squinting: Squinting or frowning when trying to see things clearly.

• Frequent Blinking or Rubbing Eyes: Blinking a lot or rubbing your eyes, especially in children with trouble seeing clearly.

It occur when the shape or structure of the eyes prevents light from focusing correctly on the retina, leading to blurry vision. There are three main causes, which are as follows:

1. Eyeball Length: The most common cause is an abnormal eyeball length. If the eyeball is too long, it results in nearsightedness (myopia). Conversely, if it's too short, it leads to farsightedness (hypermetropia).

2. Corneal Curvature: An irregular curvature of the cornea can also cause refractive errors. If the cornea is too steep, it leads to myopia, while a flatter cornea causes hypermetropia. Additionally, an uneven corneal surface can result in astigmatism.

3. Refractive Index: Light must pass through the cornea and lens correctly to focus on the retina. An abnormally high refractive index causes myopia, while a low refractive index leads to hypermetropia.

Risk Factors of Refractive Errors

Worldwide, over 2.2 billion people are estimated to struggle with either nearsightedness or farsightedness. Out of these, about 1 billion people have moderate to severe vision loss or blindness caused by uncorrected refractive errors, affecting around 88.4 million individuals.

It can affect anyone, but certain factors increase the likelihood of developing them. These include:

• Family History: Having parents or siblings with refractive errors increases the risk.

• Age: Children, teens, and older adults are more prone to this condition due to natural changes in the eye.

• Prolonged Near Work: Activities like reading, writing, or using digital screens for extended periods can contribute to these vision problems.

• Environmental Factors: Spending limited time outdoors and being exposed to dim lighting conditions may raise the risk.

• Eye Injuries or Surgery: Previous eye trauma or surgery can alter the shape of the eye, leading to refractive errors.

While refractive errors of the eye can be corrected with glasses, contact lenses, or surgery, it is always better to prevent them from developing in the first place. Here are some tips for preventing this condition:

1. Get regular eye exams: Regular eye exams are essential for maintaining good eye health. Eye exams can detect early signs of vision problems and allow for prompt treatment before the condition worsens.
2. Practice good eye hygiene: Good eye hygiene, such as washing your hands before touching your eyes and avoiding rubbing your eyes, can help prevent eye infections and other conditions that can contribute to refractive errors.
3. Take breaks from screen time: Prolonged screen time can lead to eye strain and fatigue, contributing to this condition.
   
   Taking regular breaks from screen time and practising the 20-20-20 rule (looking away from the screen every 20 minutes for 20 seconds at something 20 feet away) can help reduce eye strain.
4. Wear protective eyewear: Wearing protective eyewear, such as safety glasses or goggles, can help prevent eye injuries, preventing refractive error.
5. Maintain a healthy lifestyle: A healthy lifestyle, including a balanced diet and regular exercise, can help prevent eye conditions and other health problems.

Refractive errors can be easily detected through a simple eye exam.

Diagnosis in Adults

• Visual Acuity Test: This test checks how clearly you can see objects at various distances.

• Refraction Test: Determines the correct prescription for glasses or contact lenses to improve your vision.

• Slit-Lamp Exam: Allows the ophthalmologist doctor to examine the different parts of your eye, such as the cornea and lens, to detect any issues.

Diagnosis in Children

Early detection is especially important for children, as untreated vision problems can affect their learning and development.

If not caught early, it can lead to amblyopia (lazy eye). For younger children who may not be able to use standard eye charts, a doctor may use:

Retinoscopy: A test that examines how light reflects off the retina to assess vision. This may involve dilating the pupils with eye drops to get a clearer view.

How to prepare for a doctor’s consultation?

Make an early appointment to visit the doctor's clinic. Carry previous medical reports (if any). The doctor will ask questions about the undergoing treatment (in case of any eye disorders). 

The patient can also ask the eye specialist the following questions:

• Can refractive errors be treated without surgery?

• Will eyeglasses or lenses correct my refractive error?

• Do I need LASIK, or is there an alternative?

• What is the recovery period after surgery?

• Will the refractive error affect my vision permanently?

• What are the risks of refractive errors, including blindness?

I recently saw a patient who had been struggling with blurred vision for years, unaware that it was due to an uncorrected refractive error. The frustration of not seeing clearly had impacted her work and daily life, but she didn’t realize that a simple eye exam could change everything.

After diagnosing her condition and prescribing the right corrective lenses, she was amazed at the clarity and comfort she regained. Early diagnosis of refractive errors not only improves vision but also prevents potential complications down the road."

-  Dr Jaideep Dhama
Ophthalmology

Non - Surgical Options

Children who experience a rapid increase in myopia (about half a diopter per year) until their teenage years are at a higher risk of developing severe myopia and serious eye conditions, like macular myopathy.

People with myopia are also more likely to develop cataracts, and treating cataracts in those with severe myopia can be more complicated.

It can be managed effectively with various non-surgical options. An ophthalmologist may recommend:

1. Eyeglasses

• Reading Glasses: Ideal for presbyopia, helping with close-up tasks.

• Single-Vision Lenses: Suitable for clear vision at one distance but not for both near and far.

• Multifocal Lenses: Correct both myopia and hyperopia.

2. Contact Lenses

• Soft Lenses: Comfortable and widely used for general vision correction.

• Hard Lenses: Provide clearer images but require an adjustment period.

• Extended Wear Lenses: Can be worn continuously for up to 30 days, though they carry a risk of infection.

• Single-Use Lenses: Designed for one-time use per day.

• Reusable Lenses: Used for 7 to 30 days, needing daily cleaning and removal at night.

• Daily Wear Lenses: Worn during the day and removed before sleeping, requiring daily cleaning.

Surgical Options

When non-surgical methods aren't enough to correct refractive errors, surgical options may be recommended. The surgical approaches include:

1. LASIK: The advanced laser surgery reshapes the cornea to improve vision and correct refractive errors.

2. Conductive Keratoplasty (CK): It is used to treat hyperopia (farsightedness) in adults over 40 by reshaping the cornea.

3. Photorefractive Keratectomy (PRK): A laser is used to alter the shape of the cornea, helping correct myopia (nearsightedness), hyperopia, and astigmatism. It's a good option for those with active lifestyles.

If left untreated, it can lead to severe risks and complications. Some of them are as follows: 

• A higher degree of near-sightedness or myopia may cause retinal detachment requiring surgical repair 
• Lazy eye (amblyopia) in children
• Eye strain and fatigue
• Headache
• Increased risk of accidents
• Reduced quality of life

When to see a doctor? 

One must visit a eye doctor if they have trouble seeing faraway or nearby objects. Moreover, one must seek urgent medical care if they face: 

• Extreme headache or eye pain
• Eye irritation of infection
• Dry eyes
• Immediate loss of vision 
• Flashes in eyes

Diet plays a major role in the formation as well as in the treatment of refractive error. Therefore, people with this condition must pay proper attention to the foods they consume.

Given below is a list of food that people with refractive error should eat and should not eat. 

Foods to Eat:

• Carrot
• Spinach
• Almond
• Indian gooseberry
• Coconut

Foods Not to Eat:

• Food high in sugar content
• Processed meat
• Junk food
• Saturated fat

It is a significant and well-documented public health concern. Ophthalmologists can often detect refractive errors by asking about vision problems, like blurred vision, and related symptoms, such as headaches during activities like reading or studying. Regular screening is needed for the early detection and correction of refractive disorders.

At HexaHealth, we understand the impact of refractive errors on your quality of life. Don't wait; schedule a consultation with us today to explore your options in finding the right doctor and start your journey toward a better vision.

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