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A refraction test, also called a vision test, is usually performed as a part of a routine eye examination. The purpose of this test is to determine if a person has a refractive error which would then mean the patient would need glasses or contact lenses.
What Is The Normal Value for Refraction Test?
A value of 20/20 is normal (optimum) vision. This means that individuals who have 20/20 vision are able to read letters that are 3/8-inch (1 centimeter) tall from 20 feet (6 meters) away. The normal uncorrected vision (without glasses or contact lenses) refractive error is zero (plano). Individuals who don’t have 20/20 vision, have what is called a refractive error. A refractive error means that the light is not bending properly when it passes through the lens of the eye. The refraction test will tell the doctor what prescription lens should be used in order to have 20/20 vision.
For people over age 40 who have normal distance vision but difficulty with near vision, a refraction test with a small type size is used to determine normal near vision and the correct power of reading glasses.
How Is The Refraction Test Performed?
The test is performed by having the patient seated in a chair that has a special device (called a phoropter or refractor) attached to it. The patient looks through the device and focuses on an eye chart 20 feet (6 meters) away. The device contains lenses of different strengths that can be moved into the patient’s view. The test is performed one eye at a time. If the patient is wearing contact lenses, they should be removed before the test.
In case the final vision is less than 20/20 even with lenses, then there is probably another non-optical problem with the eye. The vision level achieved during the refraction test is called the best-corrected visual acuity (BCVA).
What Are The Causes of Abnormal Refraction Test Results?
Abnormal results may be due to:
Astigmatism (abnormally curved cornea causing blurred vision)
Hyperopia (farsightedness)
Myopia (nearsightedness)
Presbyopia (inability to focus on near objects that develop with age)
Other conditions under which the test may be performed:
Corneal ulcers and infections
Loss of sharp vision due to macular degeneration
Retinal detachment (separation of the light-sensitive membrane (retina) in the back of the eye from its supporting layers)
Retinal vessel occlusion (blockage in a small artery that carries blood to the retina)
Retinitis pigmentosa (an inherited disorder of the retina)
There is an art to refraction and the optometrist will always answer the patient’s questions and as well as discuss their findings. Based on the results of the refraction test, they can determine the amount of myopia, hyperopia or astigmatism.
The parts of a comprehensive eye examination vary according to the patient's age, date of last exam, and other factors. Not all parts of the eye exam may be needed or performed, but the first part of the eye exam will include documenting medical history. Here are some eye and vision tests that are likely to be encountered during a comprehensive eye exam:
Visual Acuity Tests
Visual acuity tests measure the sharpness of vision and are usually performed using a projected eye chart to measure the distance visual acuity and a hand-held small acuity chart to measure the near vision (for reading).
Color Blindness Test
A screening test that checks the color vision is often performed early in a comprehensive eye exam to rule out color blindness.
Cover test to check eye alignment.
A test used to assess strabismus or a more subtle binocular vision problem that could cause eye strain or amblyopia (lazy eye).
Ocular Motility (Eye Movements) Testing
Ocular motility testing is performed to determine how well eyes can follow a moving object and/or quickly move between and accurately fixate on two separate targets.
Stereopsis (Depth Perception) Test
This is used to test perception of depth and 3-dimensional structure obtained on the basis of visual information deriving from two eyes by individuals with normally developed binocular vision.
Retinoscopy
This test is used to estimate which lens powers will best correct distance vision. Based on the way the light reflects from the eye, the doctor is able to obtain an approximation of the eyeglass prescription. This test is useful for children and patients who are unable to accurately answer the doctor's questions.
Manual refraction with a phoropter.
This is the test used to determine the exact eyeglass prescription.
Macular degeneration, commonly referred to as age-related macular degeneration (AMD), is the single largest cause of sight loss in the developed world and affects more than 10 million Americans. It usually affects people over the age of 60, but has been known to affect those who are younger. It is a painless condition that usually affects both eyes with the loss being experienced in the central vision. It does not affect the peripheral vision, meaning that it does not cause total blindness.
What is the macula?
The macula is the most sensitive part of the retina and is responsible for our central vision and what allows us to see fine details with clarity.
Varieties of AMD
Wet AMD
Wet AMD is one variety of the condition in which abnormal blood vessels grow into the macula, leaking blood or fluid which then causes scarring and a rapid loss of central vision. Wet AMD can develop suddenly and rapid referral to a specialist is essential as it can be treated if caught quickly.
Dry AMD
Dry AMD is the most common variety of age-related macular degeneration and is a gradual deterioration of the retina as the cells die off over time and are not regenerated. Up to 15% of people with dry AMD go on to develop wet AMD, and so any sudden changes in your vision should be followed up with your optometrist as soon as possible.
When you were a kid, did you experience your eyes become reddish and all of a sudden, someone close to you was also suffering from it? Your eyes, as well as those who contracted it, got itchy and swollen, right? Then it must have been that you were suffering from pink eye.
Pink eye is well known as conjunctivitis and it is the infection or inflammation of the conjunctiva or the transparent membrane that serves as a covering for the white part of the eye called the sclera that lines the eyelid. In addition to inflammation, there is usually tearing in the eyes that emits a sticky discharge which develops into a crust while one is sleeping, making it difficult for the patient to open their eyes in the morning.
One thing about the pink eye, which could affect one or both eyes, is that it is highly contagious. While it is more common in children, adults can also be victims of this eye condition. Here are the 3 major causes of pink eye:
Bacteria
Streptococci and staphylococci are bacteria types that are most responsible for pink eye. However, chlamydia and gonococci can also cause pink eye. It is accompanied by serious eye pain, itching, swelling, redness, and discharge. The spread of bacterial pink eye is usually as a result of using personal items of infected parties, such as makeup or makeup tools that have been infected with bacteria or putting dirty hands in the eyes. If not treated, it can last for more than 10 days, but if treated, it should resolve in less than 3 days.
Allergies
Pink eye caused by allergies is followed by serious itching and tearing of the eyes. Pain is minimal, but it typically comes with quite a bit of discomfort. Most of the time, pink eye is accompanied by sneezing or coughing. Allergens that trigger pink eyes include grass, dust, pollen, mold, and ragweed. Allergy based pink eye is not usually contagious.
Viruses
Viruses such as the adenoviruses and herpes virus are the most common causes of pink eye. When a virus is the cause, there is usually a lot of teary discharge accompanied by nasal congestion, puffy eyelids, runny nose, and sharp pain. It is usually contracted from cough and sneeze droplets from an infected individual. It can take as long as 2 weeks to treat depending on the seriousness of the infection.
General Symptoms of Pink Eye:
Itchy eyes
Redness of the sclera
Pain
Watery discharge
Swollen eyelids
Hazy or blurry vision
Oversensitivity to light
Prevention
The best way to prevent pink eye is by practicing good hygiene which includes:
Avoid putting dirty hands in your eyes
Make it a habit to wash your hands often
Avoid sharing towels and other personal items
Do not use dirty items
Changing your pillow cover regularly
Do not leave a makeup item open for too long
Avoid sharing makeup items like eyeliners, mascara, etc.
Treatment of Pink Eye
The treatment of pink eye is dependant on its underlying cause. If it is caused by a virus, you just might have to wait for the virus to run its course which could last for about four to seven days. Virus caused pink eye could be easily contracted so it is imperative to try and prevent further spreading. Viruses cannot be cured by antibiotics, but some antiviral drugs could be helpful.
Antibiotics are most effective against pink eye caused by bacteria as they reduce the lifespan of these bacteria and could come in the form of eye drops or pills. Based on the doctor’s prescription, an eye drop should be administered about four to six times daily. It is important you finish using your drugs even after the disappearance of symptoms.
To deal with pink eyes caused by allergies, the allergy should be treated. Once treated, pink eye should disappear. It is also important to avoid allergens as much as possible so as to avoid pink eye.
Whenever the symptoms of pink eye emerge, the best preventive measure is to stay at home until the watery discharge ceases to avoid the spread of the bacteria or virus. You should also visit your doctor immediately to begin treatment. While mild pink eyes generally go away on its own, some of the more serious forms can cause a scar on the cornea.
What Is Demodex?
The Demodex mite is a type of parasite that lives on humans and can reside in hair follicles and sebaceous glands. These mites are arachnid (eight-legged) and invisible to the naked eye, varying in size from 0.1mm to 0.4 mm long. They typically live on the face and in the hair follicles of the eyebrows, eyelids, roots of the eyelashes, facial hair, and around the ears and are associated with various skin problems of the eyes and face, such as blepharitis and acne rosacea.
Demodex can affect humans at any age, but their presence increases in prevalence with increasing age. Immunity compromised patients such as diabetics, patients on long-term corticosteroids or chemotherapy, or patients who have HIV/AIDS also have increased risk and prevalence of Demodex infection. Usually, when the immune system is weakened and the parasitic population has colonized, this disease can badly damage the skin.
How Can Demodex be Transmitted?
For transmission of mites from one person to another, direct contact of hair and sebaceous glands on the nose, or dust containing eggs is required. Since the disease processes begin when there is an overpopulation of Demodex, the vast majority of cases of mites go unobserved and don't show any adverse symptoms. However, in certain cases, the mite populations migrate and multiply in the eyelashes.
What Are The Types of Demodex?
There are two existing types of Demodex mites: the longer kind, Demodex folliculorum, which live in the hair follicles and the short ones, Demodex brevis, which live in the sebaceous (oil) glands in the skin.
What Are The Symptoms of Demodex?
In the early stages, there are often no noticeable symptoms, but if left untreated Demodex can progress. Symptoms vary among patients and may include dry eye, red eyes, severe itching along the eyelid margin and eyebrow, especially in the morning, eyelid irritation, burning sensation, foreign body sensation that seems to originate beneath the eyelids, heavy lid, and blurry vision. One of the earliest signs of mite infestation is cylindrical dandruff (CD), which is the accumulation of fine, waxy, dry debris that collects at the base of the lash and extends up to 2 mm along the length of the lashes and is most noticeable on the upper lashes.
Low vision is a term for conditions that result in reduced sight and cannot entirely be corrected with eyeglasses, contact lenses, medicines or surgery. Several eye diseases or conditions can cause low vision and here we will discuss the four most common causes of low vision and their risk factors.
Macular Degeneration
Macular degeneration is a disorder that affects the retina, which is the light-sensitive tissue lining the inside of the eye. Within the retina, the area responsible for sharp central vision (called the macula) deteriorates, causing blurred vision. This can cause a blind spot in the central area of vision, which leads to low vision.
There are two types of macular degeneration – non-exudative (dry form) and exudative (wet form). The dry form usually progresses slowly, while the wet form causes more rapid and severe vision loss due to abnormal blood vessels developing under the macula and leak fluid and blood. The biggest risk factor for macular degeneration is age. Other risk factors include genetics, race, smoking, and high blood pressure.
Diabetic Retinopathy
Diabetic retinopathy is a diabetes complication that affects the eyes. High blood sugar levels cause damage to blood vessels in the retina. These blood vessels can swell and leak (called macular edema). Sometimes they close, stopping blood from passing through (called macular ischemia). At first, diabetic retinopathy may cause no symptoms or only mild vision problems. However, over time, it can severely damage the retina, leading to low vision. Anyone who has diabetes can develop diabetic retinopathy. The risk increases for those who have had diabetes longer, as well as those with poor control of blood sugar levels, high blood pressure or cholesterol as well as those who smoke.
Cataracts
A cataract is a clouding of the lens in the eye that affects vision. This clouding can block the light from reaching the retina at the back of the eye, resulting in a general loss of vision. In some cases, a cataract can be surgically removed. Cataract surgery has a high success rate in otherwise healthy eyes but it is not always possible for people who also have other eye diseases. While the risk of cataract increases as you get older, other risk factors include diabetes, smoking, alcohol use, and prolonged exposure to ultraviolet sunlight.
Glaucoma
Glaucoma is a disease that damages your eye’s optic nerve. Most commonly, this occurs when fluid builds up in the front part of your eye which increases the pressure in your eye, damaging the optic nerve. There are four types of glaucoma: open-angle, normal tension, angle-closure, and secondary.
LASIK is the number one elective surgical procedure today, and more than a million Americans have had the procedure since its inception. The main reason for its popularity is the many benefits that it offers, including minimizing or in some cases even eliminating the need for the patient to use eyeglasses or contact lenses after the procedure.
Let’s take a look at why LASIK is taking the ocular world by storm.
Better vision
Clearly, the biggest reason for choosing LASIK is improved vision. While some patients have relatively mild problems with their eyesight, others experience major disturbances in their vision that makes functioning day to day almost impossible without the use of visual aids. LASIK can dramatically improve the quality of your vision, reducing the need to wear visual aids, or in some cases, completely eliminating it.
A good investment
Eyesight is also notoriously inconsistent, with the majority of people finding that their vision marginally improves or deteriorates with each visit to their optician. When this happens, it is necessary for the optician to recommend a different prescription, and this means expense as the patient finds themselves purchasing new eyeglasses or contacts to reflect their new visual requirements.
Although there is no guarantee that you will be able to completely prescription-free after LASIK, most patients find that eyesight is so improved that any changes to their prescription are much less frequent.
Eyeglasses and contacts are known for being fiddly and fragile, and the need for maintenance and replacements are a common complaint. However, with less need for such devices, the cost of caring for them is also reduced.
A short, painless procedure
LASIK surgery can be performed in one, very short procedure. You should expect to spend around 30 minutes in the surgery suite, but the actual time it takes can be as little as 10 minutes – for both eyes! The remainder of the time will be spent preparing you and ensuring you are comfortable afterward. The entire process is carried out after anesthetic drops have been placed into your eyes, so you can rest assured you will feel absolutely no pain throughout. However, if you are particularly anxious about the process, it may be possible to be given a sedative to help you relax.
If you dislike wearing glasses and you are not a suitable candidate for laser eye surgery, then implantable contact lenses (ICL’s) may offer the permanent vision correction solution that you require.
How do implantable contact lenses work?
Implantable contact lenses basically work in exactly the same way as standard, external contact lenses do. ICL’s alter the shape of the cornea in order to correct refractive errors such as near and far-sightedness, and astigmatism. However, unlike non-permanent contact lenses, ICL’s are surgically placed inside the eye rather than over the top of it.
Implantable contact lenses are also sometimes known as phakic intraocular lenses (IOL’s). The reason for this is because the two share a number of characteristics. IOL’s are seen in cataract surgery where they take the place of the affected natural lens after it has been removed. However, when used as implantable contact lenses they work in conjunction with the natural lens of the eye in order to correct your vision.
What happens during the procedure?
The procedure requires your surgeon to make a tiny incision into the cornea to allow access to the natural lens underneath. The ICL is then inserted through the incision and placed either in front of or behind the iris which is the colored part of your eye and in front of the natural lens. The incision into the cornea is able to heal naturally without stitches, and the entire process is extremely quick.
Will it hurt?
Your surgeon will give you anesthetic, usually in the form of eye drops, ahead of the procedure and therefore you should experience very little, if any, discomfort.
Eye emergencies cover a range of incidents and conditions such as; trauma, cuts, scratches, foreign objects in the eye, burns, chemical exposure, photic retinopathy, and blunt injuries to the eye or eyelid. Since the eye is easily damaged, serious complications can occur from an eye injury thus, any of these conditions without proper treatment can lead to a partial loss of vision or even permanent blindness. Likewise, certain eye infections, other medical conditions, such as blood clots or glaucoma, and eye problems such as a painful red eye or vision loss that are not due to injury also need urgent medical attention.
Depending on the type of injury, any of the following symptoms may be present:
Bleeding or other discharge from or around the eye
Bruising
Decreased vision
Double vision
Loss of vision, total or partial, in one eye or both
Pupils of unequal size
Eye pain
New or severe headaches
Itchy eyes
Redness or bloodshot appearance
A sensation of something in the eye
Sensitivity to light
Stinging or burning in the eye
One eye is not moving like the other
One eye is sticking out or bulging
Nausea or headache occurring with eye pain (this may be a symptom of glaucoma or stroke).
A black eye is usually caused by direct trauma to the eye or face, causing a bruise resulting from bleeding under the skin. The skin around the eye turns black and blue, gradually becoming purple, green, and yellow over several days. Swelling of the eyelid and tissues around the eye may also occur. The abnormal color usually disappears within 2 weeks.
A blow to the eye can potentially damage the inside of the eye. Trauma is also a common cause of hyphemia, which is blood inside the front of the eye and is often due to a direct hit to the eye from a ball. Besides, certain types of skull fractures can cause bruising around the eyes, even without direct injury to the eye.
A chemical injury to the eye can be caused by a work-related accident, common household products such as cleaning solutions, garden chemicals, solvents, or other types of chemicals. Fumes and aerosols can also cause chemical burns. With acid burns, the haze on the cornea often clears and there is a good chance of recovery. However, alkaline substances such as lime, lye, drain cleaners, and sodium hydroxide found in refrigeration equipment may cause permanent damage to the cornea. It is important to flush out the eye with large amounts of clean water or salt water (saline).
If you’ve been diagnosed with cataracts, you may wonder if cataract surgery is right around the corner. Not to worry. There are many preventive steps you can take to slow the progression of cataracts and preserve your vision. That doesn’t mean you won’t eventually need surgery, but you can at least delay the need for quite a while.
Protect Your Eyes from the Sun
The National Eye Institute recommends protecting your eyes from the sun's harmful ultraviolet (UV) and high-energy visible (HEV) rays by always wearing good quality sunglasses while outdoors. Look for sunglasses that block 100 percent of UV rays and absorb most HEV rays with large lenses or a close-fitting wraparound style. Remember that the peak hours for sun exposure are between 10 am and 3 pm or 11 am and 4 pm during daylight savings time and that the sun’s rays are strong enough to pass through clouds, so you need your sunglasses every day.
Avoid Steroid Eye Drops
Steroid eye drops are routinely prescribed to treat dry eyes or an arthritic flare-up in the eyes. Unfortunately, they can also speed up the progression of cataracts. Talk to your Optometrist about how you can manage both conditions without inadvertently making your cataracts worse – and hastening the need for surgery.
Check Your Medications
There are over 300 commonly prescribed medications with side effects that may impact cataract progression. Since your primary care physician may not have access to your eye doctor’s medical records, be sure to ask your doctor if your current medications will affect your cataracts. If you must stay on the medication, it’s even more important to avoid sunlight during peak hours and to wear sunglasses.
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