At our hospital we use a wide variety of tests & procedures to examine your eyes. The comprehensive eye examination provides the means to evaluate the function health of the eyes & visual system. It also provides the means to identify the presence of other ocular or systematic conditions that may exist without symptoms. Examination is a dynamic & interactive process. It involves collecting subjective data directly from the patient & obtaining objective data by observation, examination & testing. The nature of the eye examination is such that many conditions can produce the same or similar symptoms. For example blurred vision can be result from many causes including uncorrected refractive errors, systematic conditions such as diabetes mellitus or hypertension. In addition potentially blinding conditions such as glaucoma or diabetic retinopathy may cause no symptoms until they are far advanced & the ocular damage is irreparable.
The goals of the comprehensive eye & vision examination are-
a) To evaluate the functional status of the eyes & visual system taking into account special vision demands & needs.
b) Assess ocular health & related systematic health conditions.
c) Establish a diagnosis.
d) Formulate a treatment & management plan.
e) Counsel & educate the patient regarding his or her visual, ocular & related systematic health care status including recommendations for treatment, management & further care.
Some eye & vision tests that you are likely to encounter during eye exam-
Auto Refraction (AR)- We use AR to automatically estimate your eye glass prescription. A chinrest stabilizes your head while you look into the instrument at a pin point of light or a detailed image. It determines the power of your eye required to accurately focus light on your retina.
Non Contact Tonometer (NCT)- NCT is a test that helps detect glaucoma. By directing a quick puff of air onto the eye it can detect elevated eye pressure. The test begins with you putting your chin on the machine’s chin rest. While you look at a light inside the machine, a puff of air will be blown at your open eye. It is completely painless and the tonometer does not touch your eye. Based on your eye’s resistance to the puff of air, the machine calculates your intraocular pressure (IOP). If you have high eye pressure, you may be at risk for or have glaucoma.
Visual Acuity Tests- In this test our optometrists measure the sharpness of your vision. These usually are performed using a projected eye chart to measure your distance visual acuity and a small, hand-held acuity chart to measure your near vision.
Dilated Eye Exam- Dilation is an important part of a comprehensive eye exam because it enables your eye care professional to view the inside of the eye. Drops placed in each eye widen the pupil, which is the opening in the center of the iris (the colored part of the eye). Dilating the pupil allows more light to enter the eye the same way opening a door allows light into a dark room. Once dilated, each eye is examined using a special magnifying lens that provides a clear view of important tissues at the back of the eye, including the retina, the macula, and the optic nerve.
Retinoscopy- In retinoscopy, the room lights will be dimmed and your eye doctor will shine a light at your eye and flip lenses in a machine in front of your eyes. This test estimates which lens powers will best correct your distance vision. Based on the way the light reflects from your eye, your doctor is able to “ballpark” your prescription. This test is especially useful for children and patients who are unable to accurately answer the doctor’s questions.
Slit Lamp Exam- A slit lamp is a binocular microscope (or “biomicroscope”) that your eye doctor uses to examine the structures of your eye under high magnification. It looks somewhat like a large, upright version of a microscope used in a science lab. During the slit lamp exam, you will be asked to place your forehead and chin securely against the rests on the front of the instrument and your doctor will begin by examining the structures of the front of your eyes — including your eyelids, cornea, conjunctiva, iris, and lens. With the help of a hand-held lens, your doctor may also use the slit lamp to examine structures located farther back in the eye, such as the retina and optic nerve.
A wide range of eye conditions and diseases can be detected with the slit lamp exam, including cataracts, macular degeneration, corneal ulcers and diabetic retinopathy, etc.
Glaucoma Test- Apart from NCT another type of glaucoma test is performed with an instrument called an Applanation Tonometer. For this test, your eye doctor will put yellow eye drops in your eye to numb it. Your eyes will feel slightly heavy when the drops start working. This is not a dilating drop, it is a numbing agent combined with a yellow dye that glows under a blue light. Then the doctor will have you stare straight ahead into the slit lamp while he or she gently touches the surface of your eye with the tonometer to measure your IOP. Like NCT, applanation tonometry is painless. At most, you may feel the tonometer probe tickle your eyelashes. The whole test takes just a few seconds. You typically have no warning signs of glaucoma until you already have significant vision loss. For this reason, routine eye exams that include tonometry are essential to rule out early signs of glaucoma and protect your eyesight.
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Doctors TimetableHere at medicenter we have individual doctor’s lists. Click read more below to see services and current timetable for our doctors.
- Monday – Friday
8.00 – 17.00
9.30 – 17.30
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- Monday – Friday
The cornea is the eye’s outermost layer. It is the clear, dome-shaped surface that covers the front of the eye. Although the cornea is clear and seems to lack substance, it is actually a highly organized group of cells and proteins. Unlike most tissues in the body, the cornea contains no blood vessels to nourish or protect it against infection. Instead, the cornea receives its nourishment from the tears and aqueous humor (a fluid in the anterior portion of the eye) that fills the chamber behind it. The cornea must remain transparent to refract light properly, and the presence of even the tiniest blood vessels can interfere with this process. To see well, all layers of the cornea must be free of any cloudy or opaque areas.
Structure- The corneal tissue is arranged in five basic layers, each having an important function. These five layers are:-
Epithelium- The epithelium is the cornea’s outermost region, comprising about 10 percent of the tissue’s thickness. The epithelium functions primarily to: (1) block the passage of foreign material, such as dust, water, and bacteria, into the eye and other layers of the cornea; and (2) provide a smooth surface that absorbs oxygen and cell nutrients from tears, then distributes these nutrients to the rest of the cornea. The epithelium is filled with thousands of tiny nerve endings that make the cornea extremely sensitive to pain when rubbed or scratched. The part of the epithelium that serves as the foundation on which the epithelial cells anchor and organize themselves is called the basement membrane.
Bowman’s Layer- Lying directly below the basement membrane of the epithelium is a transparent sheet of tissue known as Bowman’s layer. It is composed of strong layered protein fibers called collagen. Once injured, Bowman’s layer can form a scar as it heals. If these scars are large and centrally located, some vision loss can occur.
Stroma- Beneath Bowman’s layer is the stroma, which comprises about 90 percent of the cornea’s thickness. It consists primarily of water (78 percent) and collagen (16 percent), and does not contain any blood vessels. Collagen gives the cornea its strength, elasticity, and form. The collagen’s unique shape, arrangement, and spacing are essential in producing the cornea’s light-conducting transparency.
Descemet’s Membrane- Under the stroma is Descemet’s membrane, a thin but strong sheet of tissue that serves as a protective barrier against infection and injuries. Descemet’s membrane is composed of collagen fibers (different from those of the stroma) and is made by the endothelial cells that lie below it. Descemet’s membrane is regenerated readily after injury.
Endothelium- The endothelium is the extremely thin, innermost layer of the cornea. Endothelial cells are essential in keeping the cornea clear. Normally, fluid leaks slowly from inside the eye into the middle corneal layer (stroma). The endothelium’s primary task is to pump this excess fluid out of the stroma. Without this pumping action, the stroma would swell with water, become hazy, and ultimately opaque. In a healthy eye, a perfect balance is maintained between the fluid moving into the cornea and fluid being pumped out of the cornea. Once endothelium cells are destroyed by disease or trauma, they are lost forever. If too many endothelial cells are destroyed, corneal edema and blindness ensue, with corneal transplantation the only available therapy.
Function – Because the cornea is as smooth and clear as glass, but is strong and durable, it helps the eye in two ways:
1. It helps to shield the rest of the eye from germs, dust, and other harmful matter. The cornea shares this protective task with the eyelids, the eye socket, tears, and the white part of the eye (sclera).
2. The cornea acts as the eye’s outermost lens. It functions like a window that controls and focuses the entry of light into the eye. The cornea contributes between 65-75 percent of the eye’s total focusing power.
When light strikes the cornea, it bends–or refracts–the incoming light onto the lens. The lens further refocuses that light onto the retina. For you to see clearly, light rays must be focused by the cornea and lens to fall precisely on the retina. The retina converts the light rays into impulses that are sent through the optic nerve to the brain, which interprets them as images.
Disease & Disorders- Some diseases and disorders of the cornea are:-
a) Allergies- Allergies affecting the eye are fairly common. The most common allergies are those related to pollen, particularly when the weather is warm and dry. Symptoms can include redness, itching, tearing, burning, stinging, and watery discharge
b) Conjunctivitis (Pink Eye)- This term describes a group of diseases that cause swelling, itching, burning, and redness of the conjunctiva, the protective membrane that lines the eyelids and covers exposed areas of the sclera, or white of the eye. Conjunctivitis can spread from one person to another. Conjunctivitis can be caused by a bacterial or viral infection, allergy, environmental irritants, a contact lens product, eye drops, or eye ointments. At its onset, conjunctivitis is usually painless and does not harm vision. The infection will clear in most cases without requiring medical care. But for some forms of conjunctivitis, treatment will be needed.
c) Corneal Infections- Sometimes the cornea is damaged after a foreign object has entered the tissue, such as from a poke in the eye. At other times, bacteria or fungi from a contaminated contact lens can pass into the cornea. Situations like these can cause painful inflammation and corneal infections called Keratitis. These infections can reduce visual clarity, produce corneal discharges, and perhaps erode the cornea. Corneal infections can also lead to corneal scarring, which can impair vision and may require a corneal transplant.
d) Dry Eye- The continuous production and drainage of tears is important to the eye’s health. Tears keep the eye moist, help wounds heal, and protect against eye infection. In people with dry eye, the eye produces fewer or less quality tears and is unable to keep its surface lubricated and comfortable. As we age, the eyes usually produce fewer tears. Also, in some cases, the lipid and mucin layers produced by the eye are of such poor quality that tears cannot remain in the eye long enough to keep the eye sufficiently lubricated.
e) Fuchs’ Dystrophy- Fuchs’ dystrophy is a slowly progressing disease that usually affects both eyes and is slightly more common in women than in men. Although doctors can often see early signs of Fuchs’ dystrophy in people in their 30s and 40s, the disease rarely affects vision until people reach their 50s and 60s. Fuchs’ dystrophy occurs when endothelial cells gradually deteriorate without any apparent reason. As more endothelial cells are lost over the years, the endothelium becomes less efficient at pumping water out of the stroma. This causes the cornea to swell and distort vision. Eventually, the epithelium also takes on water, resulting in pain and severe visual impairment.
f) Corneal Dystrophies- A corneal dystrophy is a condition in which one or more parts of the cornea lose their normal clarity due to a buildup of cloudy material. There are over 20 corneal dystrophies that affect all parts of the cornea. Corneal dystrophies affect vision in widely differing ways. Some cause severe visual impairment, while a few cause no vision problems and are discovered during a routine eye examination. Other dystrophies may cause repeated episodes of pain without leading to permanent loss of vision.
g) Herpes Zoster (Shingles)- This infection is produced by the varicella-zoster virus, the same virus that causes chickenpox. After an initial outbreak of chickenpox (often during childhood), the virus remains inactive within the nerve cells of the central nervous system. But in some people, the varicella-zoster virus will reactivate at another time in their lives. When this occurs, the virus travels down long nerve fibers and infects some part of the body, producing a blistering rash (shingles), fever, painful inflammations of the affected nerve fibers, and a general feeling of sluggishness. Varicella-zoster virus may travel to the head and neck, perhaps involving an eye, part of the nose, cheek, and forehead. In about 40 percent of those with shingles in these areas, the virus infects the cornea.
h) Iridocorneal Endothelial Syndrome- More common in women and usually diagnosed between ages 30-50, iridocorneal endothelial (ICE) syndrome has three main features: (1) visible changes in the iris, the colored part of the eye that regulates the amount of light entering the eye; (2) swelling of the cornea; and (3) the development of glaucoma, a disease that can cause severe vision loss when normal fluid inside the eye cannot drain properly. ICE is usually present in only one eye.ICE syndrome is actually a grouping of three closely linked conditions: iris nevus (or Cogan-Reese) syndrome; Chandler’s syndrome; and essential (progressive) iris atrophy (hence the acronym ICE).
i) Keratoconus- This disorder–a progressive thinning of the cornea–is the most common corneal dystrophy in the U.S., affecting one in every 2,000 Americans. It is more prevalent in teenagers and adults in their 20s. Keratoconus arises when the middle of the cornea thins and gradually bulges outward, forming a rounded cone shape. This abnormal curvature changes the cornea’s refractive power, producing moderate to severe distortion (astigmatism) and blurriness (nearsightedness) of vision. Keratoconus may also cause swelling and a sight-impairing scarring of the tissue.
j) Lattice Dystrophy- Lattice dystrophy gets its name from an accumulation of amyloid deposits, or abnormal protein fibers, throughout the middle and anterior stroma. During an eye examination, the doctor sees these deposits in the stroma as clear, comma-shaped overlapping dots and branching filaments, creating a lattice effect. Over time, the lattice lines will grow opaque and involve more of the stroma. They will also gradually converge, giving the cornea a cloudiness that may also reduce vision. In some people, these abnormal protein fibers can accumulate under the cornea’s outer layer–the epithelium. This can cause erosion of the epithelium. This condition is known as recurrent epithelial erosion. These erosions: (1) alter the cornea’s normal curvature, resulting in temporary vision problems; and (2) expose the nerves that line the cornea, causing severe pain. Even the involuntary act of blinking can be painful.
k) Map-Dot-Fingerprint Dystrophy- This dystrophy occurs when the epithelium’s basement membrane develops abnormally (the basement membrane serves as the foundation on which the epithelial cells, which absorb nutrients from tears, anchor and organize themselves). When the basement membrane develops abnormally, the epithelial cells cannot properly adhere to it. This, in turn, causes recurrent epithelial erosions, in which the epithelium’s outermost layer rises slightly, exposing a small gap between the outermost layer and the rest of the cornea. Epithelial erosions can be a chronic problem. They may alter the cornea’s normal curvature, causing periodic blurred vision. They may also expose the nerve endings that line the tissue, resulting in moderate to severe pain lasting as long as several days. Generally, the pain will be worse on awakening in the morning. Other symptoms include sensitivity to light, excessive tearing, and foreign body sensation in the eye.
l) Ocular Herpes- Herpes of the eye, or ocular herpes, is a recurrent viral infection that is caused by the herpes simplex virus and is the most common infectious cause of corneal blindness in the U.S. Previous studies show that once people develop ocular herpes, they have up to a 50 percent chance of having a recurrence. This second flare-up could come weeks or even years after the initial occurrence. Ocular herpes can produce a painful sore on the eyelid or surface of the eye and cause inflammation of the cornea. Prompt treatment with anti-viral drugs helps to stop the herpes virus from multiplying and destroying epithelial cells. However, the infection may spread deeper into the cornea and develop into a more severe infection called stromal keratitis, which causes the body’s immune system to attack and destroy stromal cells. Stromal keratitis is more difficult to treat than less severe ocular herpes infections. Recurrent episodes of stromal keratitis can cause scarring of the cornea, which can lead to loss of vision and possibly blindness.
m) Pterygium – A pterygium is a pinkish, triangular-shaped tissue growth on the cornea. Some pterygia grow slowly throughout a person’s life, while others stop growing after a certain point. A pterygium rarely grows so large that it begins to cover the pupil of the eye. Pterygia are more common in sunny climates and in the 20-40 age group. Scientists do not know what causes pterygia to develop. However, since people who have pterygia usually have spent a significant time outdoors, many doctors believe ultraviolet (UV) light from the sun may be a factor. In areas where sunlight is strong, wearing protective eyeglasses, sunglasses, and/or hats with brims are suggested. While some studies report a higher prevalence of pterygia in men than in women, this may reflect different rates of exposure to UV light.
n) Refractive Errors – About 120 million people in the United States wear eyeglasses or contact lenses to correct nearsightedness, farsightedness, or astigmatism. These vision disorders–called refractive errors– affect the cornea and are the most common of all vision problems in this country. Refractive errors are usually corrected by eyeglasses or contact lenses. Although eyeglasses or contact lenses are safe and effective methods for treating refractive errors, refractive surgeries are becoming an increasingly popular option. Read more about refractive errors.
o) Stevens – Johnson Syndrome. Stevens-Johnson Syndrome (SJS), also called erythema multiforme major, is a disorder of the skin that can also affect the eyes. SJS is characterized by painful, blistery lesions on the skin and the mucous membranes (the thin, moist tissues that line body cavities) of the mouth, throat, genital region, and eyelids. SJS can cause serious eye problems, such as severe conjunctivitis; iritis, an inflammation inside the eye; corneal blisters and erosions; and corneal holes. In some cases, the ocular complications from SJS can be disabling and lead to severe vision loss.
Treatment- A corneal transplant involves replacing a diseased or scarred cornea with a new one. When the cornea becomes cloudy, light cannot penetrate the eye to reach the light-sensitive retina. Poor vision or blindness may result. In corneal transplant surgery, the surgeon removes the central portion of the cloudy cornea and replaces it with a clear cornea, usually donated through an eye bank. A trephine, an instrument like a cookie cutter, is used to remove the cloudy cornea. The surgeon places the new cornea in the opening and sews it with a very fine thread. The thread stays in for months or even years until the eye heals properly (removing the thread is quite simple and can easily be done in an ophthalmologist’s office). Following surgery, eye drops to help promote healing will be needed for several months.