Astigmatism: Types, Symptoms and Management

Overview

What is Astigmatism?

Astigmatism is a frequent eye condition in which the corneal and lens curvatures shift as a result of the eye’s transformation from a round to an oval shape. As light rays from an object strike the lens, the lens distributes these rays across several focal points of the retina rather than just one, creating a blurred image of the item. ¹What is astigmatism? | Researched based study from nih.gov

The eyes are one of the sensory organs of the body and are said to be a great gift to see and admire nature. Correct vision is the measure of healthy eyes. Any difficulty in vision comes under the category of Eye disorder. The eyes are also one of the most sensitive organs of our body and easily get affected by pollution, infection, aging, etc. Our vision is a complicated mechanism operated by the pupil, lens, ciliary muscles, and retina, majorly.

Process

Process of Vision

To knowing astigmatism, it is good to understand the process of healthy vision.

1. A healthy eye has a perfectly round shape and a sufficient distance between the lens and retina with a spherical cornea and properly curved lenses.
2. The cornea is the first point of passage for light. By shaping light into a cone form, the cornea aids in the eye’s ability to focus.
3. The pupil, an aperture in the eye, allows part of this light to enter. The pupil’s ability to allow light is controlled by a colored part called the iris.
4. The light then passes through the lens, where the cornea and lens combine to appropriately concentrate light on the retina.
5. Unique cells called photoreceptors are found in the retina, a layer of tissue at the back of the eye, and when light hits the retina, they transform it into electrical signals.
6. Following that, optical nerve fibers carry the electrical signals from the retina to the brain, where they are transformed into the visible image. ²Process of Vision | Researched based study from nih.gov

Any change in the shape of the eye, the curvature of the lens, the thickness of length, and, or distance of the retina can result in vision problems like Myopia(nearsightedness), Hyperopia (Farsightedness, Hyperopia) or Astigmatism(blurred vision).

Symptoms

Symptoms of astigmatism

Some common symptoms noticed in the patient with astigmatism are,

• Blurred vision both near and distant
• Headache
• Irritation of eyes
• Redness of eyes
• Stress of eyes
• Squinting when trying to see the object.

To rule out any other problem and to improve vision a visit to the doctor is a must.

Measurement

How to measure astigmatism?

• Healthy vision is measured in diopters which is a unit of the refractive power of the eye lens.
• A person with healthy eyes shows 0 D .
• People with a low degree of astigmatism can show 0.5 to 0.75 D of astigmatism, and any value above 1.5 D indicates a high degree of astigmatism, which may need the use of glasses, surgery, or other methods of treatment.

Classification

Types of astigmatism

Astigmatism falls into different categories based on the reason involved.

Basis of which parts of the eye involved

Corneal astigmatism

• Astigmatism occurs due to a defect in the cornea of the eyes.

Lenticular astigmatism

• When problem in lens causes astigmatism it is called lenticular astigmatism

 When the meridian of the eye changes

 Myopic

•  When the principal meridian became myopic.

Hyperopic

• When the principal meridian became hyperopic.

 Mixed

•  When myopic and hyperopic meridians are shown by both principal meridians

 Types based on the change in shape

Horizontal astigmatism 

• When the width of the eye increase than normal it results in horizontal astigmatism

Vertical astigmatism

•  When the length of the eye increases than normal it causes vertical astigmatism ³Types of astigmatism| Researched based study from Cdc.gov

Differences

How astigmatism is different from other refractive disorders

Astigmatism and Myopia

• Astigmatism and myopia both are refractive disorders of the eye but in myopia or nearsightedness distance between the lens and retina increases and the image of the object form before the retina instead of the retina. This leads to a blurred vision for far-off or distant objects.

Astigmatism and Hyperopia

• In hyperopia, the size of the eyeball reduces or the distance between the lens and retina decreases, and the image of the object forms behind the retina; therefore, any objects closer to the eye are not visible clearly.

Presbyopia 

• This refractive disorder is directly associated with aging, and in this state, people are not able to view objects farther than arm’s length without any aid.

Diagnosis

 Test to diagnose astigmatism

Astigmatism can be diagnosed by your ophthalmologist during a normal checkup or when you visit him due to some eye-related discomfort like myopia or hyperopia.

A patient with a complaint of low vision, blurred vision, or eye irritation is visited by the ophthalmologist, then the ophthalmologist performs a comprehensive eye examination on his dilated eye to determine the cause of the low vision and discomfort. Some specially designed eye exams can detect the presence of astigmatism.

Physical check-up

• To check the health of the patient’s eyes, the ophthalmologist instructs him to widen his eyes under the machine.

Reading the vision chart

• The doctor asks the patient to read the chart (which includes some letters and symbols) from a certain distance to know the health of her vision.

Keratometer

• A keratometer is used to examine the cornea of the eye. An injury, imperfection, or abnormality of the cornea can be diagnosed.

Autorefractor

• When a light ray enters the eye, it falls upon the retina and then returns. An autorefractor measures this process to find out if the eye has any refractive issues, which results in astigmatism.

Photoropter

• The phoropter resembles binoculars, which the patient uses to try to read letters through it, and the doctor evaluates the patient’s vision to rule out any possibility of astigmatism or other vision disorder.

Corneal topography scan

• In this test, a 3D geographical map-like image of the patient’s eye was obtained on a piece of paper with colorful fields. It displays the health of the cornea as well as the curvature to provide information about the eye’s health.

Slit lamp examination

• It is a routine test commonly conducted, especially when a patient is diabetic. In this test, the eyes are examined by the doctor using a specially designed microscope with a bright beam of light. It helps in the study of every layer of the eye.

An ophthalmologist will always examine the eyes to rule out any possibility of vision error or loss. If the patient is an elder or a child, then a detailed ophthalmic exam is mandatory.

Reasons

Reasons and causes of astigmatism

Genes

• Like myopia, astigmatism is also common in a person who is having a history of astigmatism in their family or near relatives.

 Eye injury

•  Any impact on the eye results in a change in the shape of the eyeball.

Disease or infection

• Disease or infection which results in change into the curvature of the eye and, or cornea causes astigmatism.

Screen time

• All factors are unknown yet, but doctors also believe that too long exposure to television or computer screens can also result in astigmatism.

Treatment

Treatment of astigmatism

Both non-surgical and surgical techniques of therapy are effective for controlling astigmatism.

Non-surgical procedures 

Eyeglasses

• The most popular method of treating vision issues is through the use of eyeglasses. The treatment of astigmatism involves the use of cylindrical lenses.
• A cylindrical lens’s curved surface helps the eye focus better and directs light to just one spot on the retina.

Use of contact lens

• According to claims, they offer a broader field of vision and sharper eyesight than spectacles. it is more valuable for an individual if he is physically active, such as an athlete. However, using contact lenses requires care, and young children and the elderly may not feel comfortable doing so.

Orthokeratology or ortho-k

• This method is used to compensate for low-grade astigmatism and low-grade myopia.

• Using a succession of carefully crafted contact lenses helps the patient to progressively restore the cornea’s normal curvature and enable light to refract in such a way that it focuses at the proper location on the retina.
• An ophthalmologist suggests using retainer lenses after this treatment because this method offers only transient comfort. ⁴Management of astigmatism | Researched based study from Nih.gov

Surgical methods

Conventional laser surgery for refractive correction

• Conventional methods like Excimer laser photoablation are widely adopted to correct cornea curvature and correct the refraction to treat mild astigmatism, myopia, and hyperopia.

Non-conventional wavefront-aided surgery

• It is a customized method to offer correction of the cornea by wavefront-driven photoablation of the cornea.

LASIK

• Laser-Assisted In Situ Keratomileusis or LASIK is a combination of two methods. first, a thin flap of tissue is made by microkeratome and excimer laser photoablation is used to correct the shape of the cornea.

LASEK

•  A modified version of LASIK where instead of making a flap on the cornea, the corneal epithelium is scrapped to perform photoablation and then rolled back after photoablation. both these methods Lasik and lasek are approved by the FDA for astigmatism treatment.

Photorefractive keratectomy

• The corneal epithelium is removed or scrapped away the shape of the cornea rectify by the computer-controlled excimer laser. ⁵Management of astigmatism | Researched based study from aao.org

SMILE 

• Small incision lenticule extraction or SMILE is a no-flap surgery introduced in the last decade and soon become a widely used surgery. this method gives better results in the correction of myopia and astigmatism with myopia with less or no postoperative difficulties.

Alternatives

Alternative methods in the management of astigmatism

Besides surgical and non-surgical procedures, astigmatism symptoms can also be alleviated by using some complementary yet established methods.

Exercise

• Eye exercises help relieve stress on the eye muscles and increase their focus.

Eye massage and palming

• Massage of the eye with normal pressure and in a clockwise then anticlockwise direction will ease out the strain of muscles. Rub the palms of both hands together and gently press the eyes with a warm palm.

Small and multiple breaks between work

• When someone continuously reads or works on a screen for a long time, it may cause astigmatism; therefore, an opthalmologist suggests taking small breaks during work to relax the eyes’ muscles.

Yoga

• A few yoga positions can also help in regaining the shape of the cornea by relieving stress, but it is strongly suggested to perform any yoga asana under the supervision of a trainer.

Diet

• A diet rich in vitamins and minerals is good for health; vitamin A and carotene are well-known supplements for healthy vision. A diet rich in vitamin A and carotene like papaya, mango, carrots, etc. helps in maintaining the health of the eye.

• Vitamin C, Vitamin E, and other antioxidants also show accountable results; they fight against free radicals to reduce inflammation and injury of the epithelium.

Herbs

Some herbs are widely used to treat eye strain, which helps treat astigmatism.

• Curcumin-Turmeric is a well-known source of curcumin and its benefits. The anti-inflammatory and antioxidant effects of curcumin help maintain health during various diseases like astigmatism, diabetic neuropathy, etc.

• Gentian roots-Roots of the plant Gentiana genus are well known for their therapeutic effects as anti-spasm and anti-inflammatory actions.

• Ginko Biloba-Extract or decoction of Ginko biloba roots aids in the regulation of blood flow and blood pressure that’s why said to be an as good herb for healthy vision

• Grape seed extract-Inhibition of muscle degeneration, oxidative stress, and regulation of blood flow is the major therapeutic effects of grape seeds that help in treating astigmatism and other eye problems.

• Rose water and pine extract are also used in aiding the therapeutic effects. ⁶Management of astigmatism | Researched based study from sciencedirect.com

Astigmatism management by physical exercise

• According to the research practicing frequent therapeutic exercises can effectively treat refractive problems like astigmatism. A few simple physical activities are proven to be highly helpful in improving vision and helping to reshape the cornea. ⁸Management of astigmatism | Researched based study from Ijop.net

Homeopathic remedies

• Homeopathy also contains drugs to improve vision while relieving refractive issues and eye strain. Elements like Apis mellifica, Ruta graveolens, and Physostigma are well known for the treatment of eye problems.

Ayurveda

Astigmatism management in Ayurveda

In Ayurveda, astigmatism is said to occur due to the following reasons:

• Anatomical reasons like changes in the curvature of the cornea or shape of the eyeball
• Improper body posture, especially when working on laptops, reading books, or watching television
• Laziness or insufficient physical activities
• Improper nutrition and processed food
• A problem in the refractive medium of the eyes (aqueous humor, lens, and vitreous humor)
• All of these contribute to an imbalance of vata and Kapha.

After understanding the reason behind the problem, the treatment will start, which contains

• Correction of the movement of the eyeball
• Correction of the refractive index of media
• Correcting the imbalance of vata and Kapha and reestablishing the health of optical tissues
• The treatment involves ayurvedic therapies like Sirodhara, Netratharpanam, etc., along with drugs like Triphala, Maha Triphala Ghrita, Yasthimadhu . ⁷Ayurvedic Management of astigmatism| Researched based study from Ijapr.in

In Children

Astigmatism management in Children

• The likelihood of astigmatism developing in children with refractive problems like myopia or hyperopia is higher. It has been discovered that neonates can heal themselves.
• About 30% of kids have one or other refractive condition which can hinder their ability to study and develop if ignored or untreated.
• Astigmatism-related concerns can occasionally be mistaken for other problems, like a lack of enthusiasm for study.
• Astigmatism is not curable, but its early detection and regular management are necessary to provide healthy vision.
• Especially in young children or toddle as they are unable to explain the problems, and it delays the treatment. If children have refractive disorders in their family tree, then the greatest care is necessary. 
• Regular consultation with an ophthalmologist, Healthy diet, regular exercise, less screen time and Correct body posture while reading, studying, or watching TV provides great help.
• An immediate response to any eye injury or infection helps reduce the chance of refractive disorders in kids.

Outlook

Outlook

According to the WHO, globally 153 million individuals suffer from untreated refractive defects like astigmatism, and myopia, which impair vision. Uncorrected presbyopia sufferers, who certainly make up a significant fraction of the population, are not included in this estimate. ⁹Outlook | Researched based study from Who.int

In order to make high-quality and reasonably priced health services widely available, all active members of the World Health Organization are working to connect with everyone in need, especially those who live in impoverished regions of the globe.