Astigmatism is a disorder in which the surface of the eye, or cornea, is not normally curved, resulting in blurred vision.
The irregular curve of the cornea means it is not correctly centered on the retina when light enters the eye, resulting in an ambiguous image.
An irregularly shaped lens, situated behind the cornea, can also cause astigmatism.
Children and adults may be affected. It is normally congenital, or present at birth, but can develop after an eye surgery or an eye injury.
It is one of a group of disorders in the eye called refractive errors. This arise when the cornea or lens isn’t completely smooth and curved evenly.
Other refractive errors include near- or far-sightedness and presbyopia, which happens with aging.
Refractive errors affect approximately half of all adults aged 20 years and over in the United States ( U.S.).
Important facts about astigmatism
Here are some key points about astigmatism. More information is in the main article.
- Astigmatism is a type of refractive error.
- It is a common condition.
- It is caused by an abnormal curve of the cornea or lens.
- Laser surgery can often correct astigmatism.
What is astigmatism?
Astigmatism is a term used to describe the irregular shape of the surface of the eye called the cornea.
The abnormal curve of the cornea means that when the light enters the eye, it is not correctly focused on the retina, resulting in a blurred image.
A cornea without astigmatism has a perfectly round shape, much like a ball ‘s surface.
With astigmatism, the surface of the eye is shaped more like soccer.
It focuses light on the back of the eye in two places, and this causes blur.
Astigmatism may also be caused by an irregularly shaped lens, which is located behind the cornea inside the eye.
Many children born with astigmatism will not realize that they have it until they have an eye test.
Reading and concentrating at school can be affected if the child has undiagnosed astigmatism, so regular eye tests are important.
An eye specialist may use the following tools to examine the eye:
- Visual acuity test: This involves reading letters on a chart. The letters become progressively smaller on each line.
- Astigmatic dial: A chart showing a series of lines that make up a semi-circle. People with perfect vision will see the lines clearly, while those with astigmatism will see some more clearly than others.
- Keratometer, or ophthalmometer: This device measures the reflected light from the surface of the cornea. It measures the radius of the curvature of the cornea and can assess the degree of abnormal curvature.
- Corneal topography: This process gives more information about the shape and curve of the cornea.
For children, the American Optometric Association (AOA) recommends eye tests:
- at 6 months
- at 3 years
- before first grade
- every 2 years after that
For high-risk children, an eye exam is recommended every year.
The following are common signs and symptoms of astigmatism:
- blurred or distorted vision at all distances
- excessive squinting
- eye strain, especially when the eye has to focus for long periods, as in reading from paper or a computer monitor
- difficulty driving at night
Astigmatism may not be present in a person with these symptoms, but it is a good idea to get an eye test.
Astigmatism occurs when the cornea, lens, or both are irregularly curvatured.
A translucent layer of tissue that protects the front of the eye is the cornea. It transmits light into the back of the eye and focuses it while shielding the eye from infection and injury.
A perfectly curved cornea as it reaches the eye will bend, or refract, light properly.
In an individual with astigmatism, the cornea is always egg-shaped rather than completely round, with two distinct curves. Often this is called corneal astigmatism.
The light rays will concentrate on two points on the retina instead of one because of the two different curves. This causes fuzzy vision and, if the astigmatism is serious, sometimes double vision.
Exactly why certain people are born with a cornea that does not curve properly, is unknown, but a genetic component could be present.
Compared with those born prior to their due date, a larger percentage of babies who are born preterm have astigmatism.
Some forms of surgery or damage to the eyes that cause corneal scarring can cause astigmatism.
Keratoconus is a degenerative eye disease in which the cornea slowly diminishes and changes to a more conical form. This can trigger a disorder referred to as irregular astigmatism.
The doctor may recommend no treatment at all if the astigmatism is mild.
Otherwise, the normal solution is the corrective lenses and certain people can benefit from laser surgery.
For astigmatism, corrective lenses
Corrective lenses bend the incoming light rays in such a way that the error caused by defective refraction is compensated for. Thus images are correctly projected onto the retina.
It may be in the form of contact lenses or glasses. To correct the vision, a standard prescription for near- or far-sightedness requires spherical control.
Lenses for astigmatism will need:
- a spherical power, to correct the near or far-sightedness
- a “cylinder” lens power, to correct the astigmatism
- an axis designation that describes the positioning of the cylinder correction
For children under the age of 12 years, glasses might be safer.
To of the risk of eye infection, anyone using contact lenses must be conscious of good lens hygiene.
Orthokeratology, or corneal refractive therapy
This requires, for example, wearing a specially fitted, rigid contact lens overnight to reshape the cornea. This does not permanently improve vision, but after wearing these, the person can find they can see better the whole day after.
There is a huge selection of spectacles to choose from.
Aside from the most common type of corneal astigmatism, there are other types that astigmatism can take.
This is similar to corneal astigmatism but it affects not the cornea but the lens.
The lens has variations that allow images to imperfectly hit the back of the eye, or retina, instead of a smooth curve. The majority of patients with lenticular astigmatism have a normal-shaped cornea.
Other ways of classifying astigmatism
Astigmatism can also be classified according to other established refractive errors.
Myopic astigmatism happens when astigmatism is combined with near-sightedness and the two curves are focused in front of the retina.
Hyperopic astigmatism is when astigmatism is associated with distance-sightedness and the two curves are concentrated behind the retina.
Mixed astigmatism is when one curve is far-sighted and the other is near-sighted.
Even astigmatism may be regular or irregular.
The two curves are at a 90-degree angle to each other if they are normal, but the angle is not 90 degrees if they are irregular.
Trauma, surgery, or an eye condition known as keratoconus, where the cornea gradually becomes thinner, may result in irregular astigmatism.
Laser eye surgery, the most common of which is laser in situ keratomileusis (LASIK), can treat certain people with astigmatism.
LASIK: The doctor makes a small, round hinged cut into the cornea using a device called a keratome.
The surgeon raises the flap, and under the flap, an excimer laser sculpts the shape of the cornea.
LASIK induces less discomfort than most treatments, and after a few days, the patient will regain his or her vision.
Some choices for lasers are:
Photorefractive keratectomy (PRK): This eliminates some of the cornea ‘s outer protective layer. By removing tissue an excimer laser changes the appearance of the cornea.
It typically has a more regular and spherical curve as the cornea heals. This can cause pain that is mild to extreme.
Laser epithelial keratomileusis (LASEK): The surgeon removes a thin corneal layer and uses a laser to alter the form of the cornea. It then removes the corneal tissue.
Compared with PRK, a much thinner layer is affected, making the eye less vulnerable to damage or injury. When anyone has a thin cornea and is unable to have Lasik, this surgery is often preferred. Usually it is more painful though than LASIK.
Who should avoid laser surgery?
Laser eye surgery may not be suitable if:
- the patient is aged under 18 years.
- the patient’s vision is still changing, for example, in older people. Vision should be stable for at least one year before laser surgery.
- the patient has diabetes, as surgery may worsen abnormalities in the eye caused by diabetes.
- a woman is pregnant or breast-feeding, because fluctuating hormones may cause the result to be inaccurate.
- the person has an immune condition, such as rheumatoid arthritis, lupus, or HIV, because it may be harder to recover after surgery.
- the person has another existing eye condition, such as cataracts and glaucoma, as these will need treating first.
- the person is taking certain medications such as Accutane or oral prednisone.
The risks of surgery can include:
- Refractive errors: The surgeon removes the wrong amount of tissue, and the patient’s vision worsens.
- Regression: Vision defects recur after surgery
- Visual loss: Some people’s vision might worsen after surgery
- Dry eyes: This is a common problem after laser eye surgery.
The risk of complications is low in most countries.
Patients should ensure that their surgeon is trained and knowledgeable and that an accurate examination is conducted in advance.
Allergic conjunctivitis: What to know
When a person’s eyes come into touch with an allergen, a chemical that causes the body’s immune system to respond, allergic conjunctivitis develops.
The eye gets inflamed and painful. The overactive immune system causes the body to produce histamine and other active compounds through mast cells, resulting in symptoms. The nerve terminals are irritated when blood vessels dilate or expand. As a result, the amount of tears secreted increases.
Infectious conjunctivitis differs from allergic conjunctivitis. The causes are not the same.
When the immune system overreacts to a substance, an allergic response occurs. The majority of people do not react to dust, pollen, or other substances in this way, but other people are more sensitive.
Allergens that typically cause allergic conjunctivitis include:
- eye drops
- pollen, as in hay fever
- animal fur
- dust mites.
There are different types of allergic conjunctivitis.
1) Seasonal allergic conjunctivitis or allergic rhinoconjunctivitis
In regions with cold winters, pollen is the most prevalent allergen that causes conjunctivitis.
Other symptoms of pollen-induced conjunctivitis include sneezing, an itchy, clogged, or runny nose, and itchy, watery eyes.
Hay fever is also known as seasonal allergic conjunctivitis or allergic rhinoconjunctivitis.
It generally takes place in the spring and summer. Plants, particularly grass, trees, and flowers, are in pollen during this time. Some people get symptoms in the early autumn.
2) Contact conjunctivitis
Cosmetics, eyedrops, or other chemicals that irritate the conjunctiva in people who are vulnerable induce symptoms known as contact dermatoconjunctivitis. An allergic reaction occurs when these compounds come into contact with the body. Some people are hypersensitive to certain chemicals.
After the substance comes into contact with the eyes, symptoms generally appear 2 to 4 days later.
3) Papillary conjunctivitis (giant papillary conjunctivitis)
This is a common side effect of wearing contact lenses. Contact lenses can be uncomfortable for some people. This might grow worse and more unpleasant with time, causing the eyes to become red.
When a person wears hard contact lenses following eye surgery, giant papillary conjunctivitis (GPC) can develop.
Infections of the eye can be caused by poor hygiene when handling contact lenses, solutions, and cases.
4) Perennial conjunctivitis
Perennial conjunctivitis is a kind of conjunctivitis that lasts all year. It is mostly caused by an allergy to home dust mites. These tiny insect-like critters like to reside in bedding, upholstered furniture, and carpets.
Dust mites feed on human skin cells and like warm, damp people.
An allergic reaction to a particular dust mite protein is known as dust-mite allergy. Conjunctivitis, a clogged or runny nose, sneezing, and airway tightness, as seen in asthma, are all symptoms of this.
Animal dander, minute scales from animal skins or hair, and bird feathers are among the other causes. Some people may experience an allergic response to them.
The following suggestions may help:
- Cold compresses: The eyes can be soothed by placing a wad of cotton wool soaked in cold water on the eyelid.
- Avoiding the allergen: Staying indoors while the pollen count is high, keeping the house clean, and limiting soft furnishings can all help.
- Contact lenses should be avoided at all costs: These should not be used until all symptoms have vanished. After using any eye medicine, wait at least 24 hours before putting contact lenses back on.
- Artificial tears: These eye drops dilute the allergen and help remove it.
- Refraining from rubbing the eyes: Rubbing might aggravate the irritation. It’s tempting to touch inflamed eyes, so this might be challenging.
Antihistamines, mast cell stabilizers, and corticosteroids are used to treat the condition.
Antihistamines, taken orally or as eye drops, may provide quick relief from symptoms. Histamines are blocked by antihistamines. When the immune system responds to a foreign substance, histamines are produced.
Cetirizine, fexofenadine, and loratadine are oral antihistamines used to treat allergic conjunctivitis. Once a day is generally plenty. Alaway and Zaditor are antihistamine eye drops. The eye drops will aid with eye problems, but the oral dose will help with a runny nose and other symptoms as well.
Azelastine, emedastine, and ketotifen are the most regularly prescribed antihistamine eye drops. They’re used twice or three times a day on the eyes.
Some antihistamines might make you sleepy. People who are taking them for the first time should avoid driving or using heavy machinery until they know how they will react to the drug.
Mast cell stabilizers
Mast cell stabilizers take longer to operate than antihistamines, but their effects stay longer once they do.
Lodoxamide and nedocromil are the most often used mast cell stabilizers. They are available as eye drops.
Antihistamines and mast cell stabilizers are used by certain patients. Before the mast cell stabilizers start acting, the antihistamines give some relief from symptoms.
These are only used in extreme cases and are rarely prescribed. The adrenal cortex produces corticoid, a steroid hormone. Synthetic corticosteroids are a type of drug that can reduce swelling and suppress the immune system.
Corticosteroids are effective, but they should be taken with caution and only for a short period of time due to the risk of adverse effects.
The majority of people who suffer from allergic conjunctivitis have issues with both eyes.
Symptoms may occur rapidly after coming into touch with the allergen in the eyes. Symptoms may develop after 2 to 4 days in other circumstances, such as when eye drops cause a response.
The following are some of the signs and symptoms of allergic conjunctivitis:
- Eyelids swollen: When the conjunctiva becomes inflamed or if the person rubs their eyes a lot, the eyelids may puff up.
- Soreness: The inflammation may cause pain and tenderness throughout the affected area. Some people describe the pain as burning.
- Red or pink eyes: As the capillaries, or small blood vessels, in the conjunctiva widen, the eyes become irritated.
- Pain: One or both eyes may be affected. If a person has painful, red eyes, is light sensitive, or has vision problems, they should see a doctor right away.
- Itchiness: Itching may occur as the eyes become irritated. Rubbing can aggravate the itching.
Seasonal allergic conjunctivitis affects people at specific seasons of the year, generally from early spring to summer and occasionally into fall.
Perennial allergic conjunctivitis patients are vulnerable at any time of year. They could notice that their symptoms are more severe at some times of the day than at others.
Contact conjunctivitis can be identified by red, cracked, or dry eyelids. The symptoms of contact conjunctivitis and giant papillary conjunctivitis are not seasonal, and they can appear at any time of year.
A doctor will examine the patient and inquire about signs and symptoms such as sneezing and a runny nose to diagnose allergic conjunctivitis.
Other conditions with comparable symptoms may need to be ruled out as well.
Anyone experiencing the following symptoms should contact a doctor right once, since they might be signs of a more serious problem:
- vision problems
- very red eyes
- painful eyes
- sensitivity to light, or photophobia
Aside from allergic conjunctivitis, the following disorders can cause redness in the eyes:
- Keratitis: The cornea gets irritated and ulcerated on occasion. It can sometimes lead to corneal scarring, resulting in irreversible vision loss.
- Iritis: Iris inflammation is a condition in which the iris becomes inflamed. The iris may cling to the lens if left untreated, limiting critical fluid outflow from the pupil. It’s possible that irreparable eye damage will develop.
- Infective conjunctivitis: This is caused by bacteria or virus. It’s possible that it’s caused by the herpes virus, and it might signify a sexually transmitted infection (STI).
- Acute glaucoma: In the eye, pressure builds up. Symptoms might emerge quickly. Acute glaucoma, if left untreated, can result in irreversible visual loss.
The doctor will also look to see if the discomfort is caused by an item or substance, such as an eyelash.
If the patient’s symptoms are severe or worsening, the doctor may recommend them to an ophthalmologist, or eye specialist.
After recent eye surgery, anyone who gets papillary conjunctivitis will be sent to an ophthalmologist. To ensure that therapy is effective, the eye or eyes must be closely monitored.
Complications of allergic conjunctivitis, whether chronic or seasonal, are uncommon.
Allergic conjunctivitis can have a negative influence on a person’s quality of life, although it seldom has a long-term effect on health.
Dermatoconjunctivitis and large papillary conjunctivitis can also cause complications.
It’s possible that the cornea will get inflamed. Keratitis is a condition that causes ulcers to grow on the cornea. This raises the danger of scarring and the chance of vision loss for the rest of one’s life.
Keratitis symptoms include:
- blurred vision
- a feeling that there is something in the eye
- watery eyes
- intense pain in the eye
- sensitivity to light
If any of these symptoms appear, the person should seek medical attention.
Finding out what causes allergic rhinitis and avoiding the allergen is the best method to prevent it.
Pet fur and pollen are two common allergies.
If your pet is the source of your allergy, try the following:
- wash their bedding regularly
- brush them regularly and wash them every 2 weeks
- keep pets out of the bedroom
If you’re going to a residence with a pet, taking an antihistamine one hour ahead of time may help alleviate symptoms.
If pollen causes an allergic response, do the following:
- use wraparound sunglasses to protect your eyes
- bathe and change your clothes after being outside
- try to get someone else to cut the lawn for you
- stay inside and keep doors and windows closed when the pollen count is high
- avoid areas with a lot of grass, flowers, or trees
Pollen counts are greatest in the mid-morning and early-evening hours.
If you have an allergic reaction to home dust mites, you should:
- choose anti-allergenic matresses and bedding
- vacuum often, and dust with a clean, damp cloth
- avoid soft furnishings, such as carpets and drapes
- use a vacuum cleaner with a HEPA filter
What you need to know about blepharitis
Blepharitis is a condition that affects the upper and lower eyelids. Around the eyelashes, it can cause clumping and stickiness.
Inflammation near the base of the eyelashes causes it. There are a variety of therapies available, including home remedies, that can help to alleviate symptoms.
We’ll go over what causes blepharitis, how to remedy it, and how to avoid it in this post.
Blepharitis can affect people of all ages and can be acute or chronic in nature; chronic adult blepharitis is the most frequent kind. Blepharitis is a term that refers to a persistent inflammation of the eyelids.
The symptoms of blepharitis are depicted in the images below.
Blepharitis can be caused by a variety of causes.
They are as follows:
- parasites: Demodex eyelash mites
- infection with the herpes simplex virus (HSV)
- an inflammatory reaction to bacteria that normally live on eyelids
- seborrhoeic dermatitis or rosacea
Blepharitis is more common in people who have dandruff. Controlling the dandruff might assist to ease the symptoms.
Dysfunction of the Meibomian glands on the rim of the eyelids is another probable reason. These glands secrete an oily material that keeps the tear film from evaporating in the eye.
Some clinicians feel that blepharitis is a prelude to Meibomian gland malfunction rather than blepharitis being caused by gland dysfunction.
Blepharitis can be anterior or posterior.
Anterior: This affects the eyelid’s front edge, where the eyelashes contact it.
Posterior: This affects the inner edge of the eyelid, where it meets the eyeball.
The following are the key signs and symptoms:
- burning or stinging eyes.
- oversensitivity to light (photophobia).
- gritty feeling in eyes and the sensation of having something in the eye.
- itchy eyelids.
- red eyes.
- irritated and watery eyes.
- flaking and crusting at the base of the eyelashes, similar to dandruff.
Symptoms are usually more noticeable in the mornings.
Although blepharitis is not a sight-threatening condition, it can cause temporary vision loss.
Chronic blepharitis symptoms come and go, with periods of remission (a break in the symptoms) followed by exacerbations (a flare-up). It frequently affects both eyes at the same time.
Blepharitis is usually treated with a combination of medical and home remedies.
A doctor will likely prescribe home therapy, such as the ones listed below, but they can also do the following process:
Electrochemical lid margin debridement (BlephEx): This clears the eyelids of any mites, bacteria, and the biofilm that they produce. Any congested Meibomian glands are also opened.
Thermal pulsation treatment (Lipiflow): This dissolves any clogging debris in the Meibomian glands.
Intense pulse light therapy (IPL): This helps to unclog congested eyelid glands.
Severe instances of blepharitis may necessitate the use of antibiotics, either topical or oral.
In order to treat both forms of blepharitis, it’s important to keep your eyelids clean. Even if your symptoms have improved, you should keep doing it.
The most important aspect of therapy is self-care. Blepharitis symptoms might reappear if self-care is not maintained.
Although blepharitis cannot be cured, it can be effectively managed with medication.
People with eyelid inflammation should avoid wearing cosmetics around their eyes, such as eyeliner, mascara, and other eye makeup, in addition to home therapy.
Blepharitis treatment entails:
- massage, to express the small oil glands of the eyelids
- lid cleansing, to remove crusts
- warm compresses, to loosen crusts
What is the best way to apply a warm compress?
Placing a warm compress over closed eyelids, warming the compress with warm water when it cools, and reapplying for up to 10 minutes is all it takes to use a warm compress.
The following are some suggestions:
- Using a soft cloth only: Scrubbing too vigorously or using a rough cloth can damage the skin and eyes.
- Dipping the cloth in warm water: Some patients have suffered facial burns by using a microwave to heat up the wet cloth.
Cleanse the eyelids after using a warm compress for up to 10 minutes.
Warming eye masks: These may have the same effect as warm cloth compresses while being more convenient. There are additional eyelid cleansers (Ocusoft, Thera Tears Sterilid) that can be used instead of dilute baby shampoo.
How do you clean your eyelids?
To do so, use a cotton swab soaked in a mild solution of baby shampoo to gently rub the eyelid margin—at the base of the eyelashes and where the glands are located. In roughly half a cup of warm water, drop 2 to 3 drops.
This lid hygiene must be done twice a day, every day as a self-care routine. This is a significant lifelong commitment, but without it, the symptoms will return.
How do you massage your eyes?
Massaging helps express the oily contents of the glands after applying the heated compress to release the sebum.
Massage the eyelid margin, where the eyelashes and glands are, with a finger or a cotton-tipped applicator or swab in tiny circular strokes.
These non-prescription eye drops will assist to alleviate the dryness of the eyes caused by blepharitis during the day. Artificial tears that are free of preservatives are the finest to use.
Artificial tears may be purchased over the counter, but you should first consult your doctor to ensure that they are appropriate.
Symptoms will be discussed, a medical history will be taken, and the patient’s eyelids and eyes will be examined.
The doctor will search for indicators that will help them figure out which sort of blepharitis you have. A slit lamp may be used.
This is a low-power microscope with an intense thin-beam light source that has been particularly constructed.
The doctor may examine the exterior of the eyes and the eyelids with the lamp while the patient’s head is held still by the chin and forehead resting on supports.
The doctor will next provide a therapy recommendation. This may or may not be the case, depending on the cause. A acceptable alternative will be picked if blepharitis looks to be caused by a skin condition, such as rosacea, or if it is caused by mites.
A novel laser treatment for macular degeneration may be effective
A novel form of laser treatment has the potential to reduce the course of age-related macular degeneration (AMD), a leading cause of visual loss, without causing retinal damage.
This was the finding of a research published in The FASEB Journal by the University of Melbourne in Australia.
The effectiveness of a new low-impact, low-energy laser therapy for individuals with early age-related macular degeneration (AMD) was investigated by Erica Fletcher, an associate professor at Melbourne’s Department of Anatomy and Neuroscience, and colleagues.
They discovered that, unlike previous laser therapies, the “nanosecond laser” they examined did not harm the retina, which is the light-detecting tissue at the back of the eye.
Prof. Fletcher claims that theirs is the first study to show how the novel laser treatment can help people with AMD improve their eye health.
AMD is a painless eye condition that causes central vision loss over time. It is the main cause of irreversible impairment of fine or close-up vision – such as that required for reading – among people aged 65 and older, according to the Centers for Disease Control and Prevention (CDC) (resource no longer accessible at www.cdc.gov).
According to estimates, roughly 1.8 million Americans aged 40 and over have AMD, with another 7.3 million at risk.
AMD is responsible for 48 percent of severe vision loss in Australia, where the study took conducted, with an estimated 17,700 new cases per year.
New laser treatment reduced drusen and thickness of Bruch’s membrane
In the early stages of AMD, examination of the back of the eye reveals the development of microscopic fatty deposits known as drusen, as well as a thickening of a thin layer of tissue known as Bruch’s membrane. As these symptoms increase, the core section of the retina is slowly destroyed.
According to the findings, the nanosecond laser can diminish drusen and thin the Bruch’s membrane without causing damage to the retina’s structure.
The researchers conducted a number of tests and experiments as part of the study. One study included 50 AMD patients who had a single session of nanosecond laser therapy and were followed up on two years later. Their drusen burden was lowered in comparison to a similar group of untreated individuals, according to eye tests.
The membrane was thinner three months after treatment in mice with thicker Bruch’s membrane who underwent the laser therapy.
New laser treatment did not damage the retina
The researchers used human and animal eyes to assess the new laser’s effect on the retina, for example, using a procedure called “immunohistochemistry,” which can detect minute changes in tissue structure.
The researchers state this about their research:
“Nanosecond laser resolved drusen independent of retinal damage and improved BM [Bruch’s membrane] structure, suggesting this treatment has the potential to reduce AMD progression.”
The findings “indicate that treating people with AMD with our new nanosecond laser lowers indications of the disease,” according to Prof. Fletcher.
“Most importantly,” she continues, “the nanosecond laser does not cause harm to the delicate retina, unlike other lasers now used to treat eye disease.”
The researchers also discovered evidence that using the nanosecond laser to treat one eye can have beneficial benefits on the other eye, raising the prospect that one therapy could be enough to correct disease in both eyes.
Glaucoma, in which fluid builds up in the eye and puts pressure on the optic nerve, is another main cause of blindness. The condition is treatable, but there is no treatment at this time.