Myopia (Nearsightedness) is a refractive error where distant object comes into focus in front of the retina of the eye as a result of longer than normal eye-ball, so the distant object appears blur to the myopic eye.

A bent concave lens is used to bring the focus on the retina to restore clear distance vision.

However, the myopic eye can still see near objects clearly without any correction depending on the distance of the near objects in relation to the degree of myopia.

It's important to detect and correct young children (under 6 years old) with moderate to high monocular myopia to prevent Amblyopia (lazy eye).

Hyperopia (Farsightedness) is a refractive error where distant object comes into focus behind the retina when the eyes is relaxed.

In adults, this condition will cause deterioration of distance vision and near visual problem due to the gradual loss of focusing ability of the eye. A bent convex lens is used to bring the focus back onto the retina.

In children, distance vision is often not affected because of the active and strong focusing mechanism, the eyes have ability to bring the focus back onto the retina. However, for higher degrees of hyperopia, it may cause blurred vision, headache, and even converging squints. These problems will be aggravated when doing near works which required greater focusing power.

It's important to detect and correct the medium to high degrees of hyperopia for children under 6 years old. If uncorrected, it can lead to Amblyopia.

Astigmatism is a refractive error where distant object comes into two focal lines perpendicular to one another. These lines may lie in any orientation and any position in relation to the retina. This is primarily due to the aspherical (toroidal) corneal shape.

A bent lens with a toric surface is used to correct this condition.

Astigmatism may occur by itself or may occur with one of the refractive errors. Although for a similar degree of defect, astigmatic eyes suffer less blur than the other refractive errors, uncorrected astigmatism often leads to eyestrain and headache due to the focal lines formed in the eye cause the eye's focusing mechanism under strain as it constantly exert effort for best possible focus.

Uncorrected astigmatism on young children can also lead to Amblyopia.

Presbyopia is the condition where one reaches early forties, his crystalline lens starts to lose its elasticity and gradually hardening hence its focusing power diminishes, the eye finds focusing on near objects difficult.

If the presbyope has good distance vision, he will naturally hold the reading material progressively further away for clear vision. Correction is in the form of single vision "reading glasses" or bifocal lenses or progressive power lenses.

Amblyopia (Lazy eye) is a condition where the eye's visual acuity remains poor despite best optical correction and the eye has no structural abnormality.

A child's visual development continues till he reaches the age of about 6 years old. If there is a lack of proper stimulation to any eye during this critical period from the conditions of refractive errors, squints or cataract, the visual development of that eye will be halted, and he will also not be able to develop stereoscopic vision.

Early detection and treatment is important to prevent amblyopia. Once amblyopia is established after the critical period, sub-normal vision cannot be corrected.

Strabismus (Heterotropia, Squint or Crossed eyes) is a condition of any abnormal alignment of the two eyes and is most commonly horizontal - when one eye is looking at an object, the other eye turning horizontally to another direction.

This condition can occur at any age.

The intact co-ordination of the neural pathway from the brain to the external eye muscles provides us the normal binocularity and stereoscopic vision. When this neural pathway or the external eye muscles are disrupted, strabismus results and the sufferer sees double images.

In children, the brain will learn to suppress the more deviated image thus eliminate the double vision, although the squint remains. This will lead to amblyopia of the deviating eye due to disuse, as a result of the continuing mental suppression.

Glaucoma is an eye disease in which the internal pressure in your eyes increases enough to damage the nerve fibers in your optic nerve and cause vision loss. The increase in pressure happens when the passages that normally allow fluid in your eyes to drain become clogged or blocked. The reasons that the passages become blocked are not known.

Glaucoma is one of the leading causes of blindness in the U.S. It most often occurs in people over age 40. People with a family history of glaucoma, African Americans, and those who are very nearsighted or diabetic are at a higher risk of developing the disease.

The most common type of glaucoma develops gradually and painlessly, without symptoms. A rarer type occurs rapidly and its symptoms may include blurred vision, loss of side vision, seeing colored rings around lights and pain or redness in the eyes.

Glaucoma cannot be prevented, but if diagnosed and treated early, it can be controlled. Vision lost to glaucoma cannot be restored. That is why the American Optometric Association recommends annual eye examinations for people at risk for glaucoma (your doctor may, depending on your condition, recommend more frequent examinations). A comprehensive optometric examination will include a tonometry test to measure the pressure in your eyes; an examination of the inside of your eyes and optic nerves; and a visual field test to check for changes in central and side vision.

The treatment for glaucoma includes prescription eye drops and medicines to lower the pressure in your eyes. In some cases, laser treatment or surgery may be effective in reducing pressure.

Cataracts

What is a cataract?

A cataract is a clouding of the lens in the eye that affects vision. Most cataracts are found in persons over age 55, but they are also occasionally found in younger people. By age 80, more than half of all Americans either have a cataract or have had cataract surgery.

The lens of the eye is made mostly of water and protein. Clouding of the lens occurs due to changes in the proteins and lens fibers. Age-related cataracts tend to form gradually.

Classification of Cataracts

Cataracts may be described in a number of ways including their location and their cause:

Location in the lens:

• Cortical cataract. These opacities affect the cortex of the lens, and are identified by their unique wedge or spoke appearance. This type has been shown to be related to exposure to UltraViolet radiation.
• Nuclear cataract. The nucleus is the center of the lens. As the lens ages, the nucleus tends to darken, changing from its intial clear appearance to yellow, then sometimes brown. When this darkening begins to affect vision, it is termed a nuclear cataract.
• Posterior capsular cataract. This often-dense cataract is located on the posterior of the lens. Due to its location, it often affects near vision more than it affects distance. This type of cataract can result from long-term use of steroid medications.

Cause of the cataract:

Most cataracts are age related. However, here are a few other causes of cataract:

• Secondary cataract. Cataracts can form after surgery for other eye problems, such as glaucoma. Cataracts also can develop in people who have other health problems, such as diabetes. Cataracts are sometimes linked to steroid use.
• Traumatic cataract. Cataracts can develop after an eye injury, sometimes years later.
• Congenital cataract. Some babies are born with cataracts or develop them in childhood, often in both eyes. These cataracts may be so small that they do not affect vision. If they do, the lenses may need to be removed.
• Radiation cataract. Cataracts can develop after exposure to some types of radiation.

How cataracts affect vision

When vision is clear, the lens of the eye focuses light on the back of the eye, or the retina, which transmits the image through the optic nerve to the brain. When the lens is clouded by a cataract, light scatters so the lens can no longer focus it properly, causing vision problems.

Especially in age-related cataracts, vision disruption can be very gradual. As cataracts worsen, visual symptoms tend to increase in severity. However, some patients may not recognize the change in symptoms because of a cataract’s slow progression.

Cataracts—especially nuclear cataracts—can also affect one’s ability to accurately differentiate color. As proteins in the eye age, they can develop a yellow or brown tint, causing vision to appear slightly tungsten. While this tinting may not affect the sharpness of one’s vision, it can lead to trouble with reading or determining the difference between darker colors.

Symptoms

Cataracts form without pain or discomfort. However, there are several key factors which might signal the formation of a cataract:

• blurred or hazy vision
• the appearance of spots in front of the eyes
• colors in vision seem faded or muted, or you may have difficulty distinguishing between dark colors like navy and black
• increased sensitivity to glare or the feeling of having a film over the eyes
• Double vision or multiple images (this might clear as the cataract grows larger)
• a temporary improvement in near vision

NOTE: These symptoms can be related to other vision conditions and eye diseases. If you experience any of the symptoms, it is important to see an eye care professional to determine the cause of these symptoms.

Risk Factors

Age is the primary risk factor for developing cataracts. However, there are other factors that can affect cataract development:

• Diabetes mellitus. Persons with diabetes mellitus are at higher risk for cataracts, and persons with diabetes who have cataracts have a higher morbidity than those without cataracts.
• Drugs. Certain medications have been found to be associated with the development of a cataract and vision loss. These drugs include:
  • corticosteroids
  • phenothiazine or other thiazines
  • chlorpromazine
  • Antihypertensive agents

• Ultraviolet radiation. Studies have shown that there is an increased chance of cataract formation with unprotected exposure to ultraviolet (UV) radiation.
• Smoking. An association between smoking and increased nuclear opacities has been reported.
• Alcohol. Several studies have shown increased cataract formation in patients with higher alcohol consumption compared with patients who have lower or no alcohol consumption.
• Nutrition. Although the results are inconclusive, studies have suggested an association between cataract formation and low levels of antioxidants (e.g., vitamin C, vitamin E, carotenoids). Further study may show that antioxidants have a significant effect on decreasing the incidence of cataract.

Preventive Actions

The biological processes of cataract formation are becoming more clearly understood, but there is still no clinically established treatment to prevent or slow the progression of cataract. Research on the prevention of cataract has centered on risk factors and the control of diseases, such as diabetes, which are associated with some types of cataracts.

Cataract is a multifactorial disease; different factors are associated with the development of different types of opacities. Nevertheless, a simple, low-cost and low-risk preventive strategy is to reduce exposure to sunlight, decrease or discontinue smoking, and possibly increase antioxidant vitamin intake through consumption of leafy green vegetables and/or supplements.

Diagnosis and Treatment

Cataracts can be diagnosed through a comprehensive eye examination. This examination can include procedures including:

• Patient history
• Refraction to determine a change in eyeglass prescription
• Dilated eye evaluation that allows a better view of the lens, as well as the retina
• Supplemental testing, like Visual Fields, Amsler Grid, Corneal Pachymetry/Endothelial Cell Count, B-Scan Ultrasonography, Color Vision Testing, Electrophysiology, Contrast Sensitivity and/or Glare Testing, and Potential Acuity Testing

Non-surgical treatment

The treatment of cataracts is based on the level of visual impairment they cause. Patients with little visual symptoms may be advised to monitor for increased visual disruption and follow a regular check-up schedule. It is important to remember that cataracts develop slowly, and regular examinations are key to maintaining healthy vision.

Changes in one’s eyeglass or contact lens prescription can improve many of the mild or moderate visual symptoms of cataracts. Other non-surgical treatments include:

• Lens tints and coatings to decrease glare
• Sunglasses
• Artificial tears

Surgical treatment

However, patients with greater visual disruption or related ocular diseases or conditions may require further treatment, including cataract surgery. Candidates for cataract surgery are typically those whose cataracts have decreased visual acuity to a point where there is a disruption to everyday tasks like driving.

The standard for cataract surgery today is the replacement of the clouded lens with a plastic intraocular lens (IOL). The artificial lens requires no care, and should dramatically improve vision for the patient. New IOL options include those that simulate the natural focusing ability of a young healthy lens.

It is important to discuss the benefits and risks of cataract surgery with your eye care providers. Other ocular conditions may increase the need for cataract surgery or prevent one from being a cataract surgery candidate. In some cases, alternatives to surgery may be available.

Cataract surgery is one of the safest and most effective types of surgery performed in the United States today. Approximately 90 percent of cataract surgery patients report better vision following the surgery.

The healing process for most cataract surgery patients is completed in 8 weeks

Age Related Macular Degeneration

Macular degeneration is the leading cause of blindness in America. It results from changes to the macula, a portion of the retina that is responsible for clear, sharp vision, and is located at the back of the eye.

Most people with macular degeneration have the dry form, for which there is no known treatment. The less common wet form may respond to laser procedures, if diagnosed and treated early.

Some common symptoms are a gradual loss of ability to see objects clearly, distorted vision, a gradual loss of color vision and a dark or empty area appearing in the center of vision.

If you experience any of these, contact your doctor of optometry immediately for a comprehensive examination.

Central vision that is lost to macular degeneration cannot be restored. However, low vision devices such as telescopic and microscopic lenses can be prescribed to make the most out of remaining vision.

Recent research indicates certain vitamins and minerals may help prevent or slow the progression of macular degeneration. Ask your doctor of optometry about these. After age 60, an annual, comprehensive eye examination is important to maintain eye health.

Diabetes

Diabetes is a disease that interferes with the body's ability to use and store sugar and can cause many health problems. One, called diabetic retinopathy, can weaken and cause changes in the small blood vessels that nourish your eye's retina, the delicate, light sensitive lining of the back of the eye. These blood vessels may begin to leak, swell or develop brush-like branches.

The early stages of diabetic retinopathy may cause blurred vision, or they may produce no visual symptoms at all. As the disease progresses, you may notice a cloudiness of vision, blind spots or floaters.

If left untreated, diabetic retinopathy can cause blindness, which is one reason why it is important to have your eyes examined regularly by your doctor of optometry. This is especially true if you are a diabetic or if you have a family history of diabetes.

To detect diabetic retinopathy, your optometrist can look inside your eyes with an instrument called an ophthalmoscope that lights and magnifies the blood vessels in your eyes. If you have diabetic retinopathy, laser and other surgical treatments can be used to reduce its progression and decrease the risk of vision loss. Early treatment is important because once damage has occurred, the effects are usually permanent.

If you are a diabetic, you can help prevent diabetic retinopathy by taking your prescribed medication as instructed, sticking to your diet, exercising regularly, controlling high blood pressure and avoiding alcohol and smoking.

Dry Eyes

The tears your eyes produce are necessary for overall eye health and clear vision. Dry eye means that your eyes do not produce enough tears or that you produce tears that do not have the proper chemical composition. Often, dry eye is part of the natural aging process. It can also be caused by blinking or eyelid problems, medications like antihistamines, oral contraceptives and antidepressants, a dry climate, wind and dust, general health problems like arthritis or Sjogren's syndrome and chemical or thermal burns to your eyes.

If you have dry eye, your symptoms may include irritated, scratchy, dry, uncomfortable or red eyes, a burning sensation or feeling of something foreign in your eyes and blurred vision. Excessive dry eyes may damage eye tissue, scar your cornea (the front covering of your eyes) and impair vision and make contact lens wear difficult.

If you have symptoms of dry eye, see your optometrist for a comprehensive examination. Dry eye cannot be cured, but your optometrist can help to manage the symptoms.

Blepharitis

Blepharitis is a chronic or long-term inflammation of the eyelids and eyelashes. It affects people of all ages. Among the most common causes of blepharitis are poor eyelid hygiene; excessive oil produced by the glands in the eyelid; a bacterial infection (often staphylococcal); or an allergic reaction.

Seborrheic blepharitis is often associated with dandruff of the scalp or skin conditions like acne. It can appear as greasy flakes or scales around the base of the eyelashes and a mild redness of the eyelid. It may also result in a roughness of the normally smooth tissue that lines the inside of the eyelid.

Ulcerative blepharitis is less common, but more serious. It is characterized by matted, hard crusts around the eyelashes, which when removed, leave small sores that ooze or bleed. There may also be a loss of eyelashes, distortion of the front edges of the eyelids and chronic tearing. In severe cases, the cornea, the transparent front covering of the eyeball, may also become inflamed.

In many cases, good eyelid hygiene and a regular cleaning routine may control blepharitis. This includes frequent scalp and face washing; warm soaks of the eyelids; and eyelid scrubs. In cases where bacterial infection is a cause, eyelid hygiene may be combined with various antibiotics and other medications. Eyelid hygiene is especially important upon awakening because debris can build up during sleep.

If you experience symptoms of blepharitis, your doctor of optometry can determine the cause and recommend the right combination of treatments specifically for you.

Directions For A Warm Soak Of The Eyelids

• Wash your hands thoroughly.
• Moisten a clean washcloth with warm water.
• Close eyes and place washcloth on eyelids for about 5 minutes.
• Repeat several times daily.

Directions For An Eyelid Scrub

• Wash your hands thoroughly.
• Mix warm water and a small amount of shampoo that does not irritate the eye (baby shampoo) or use a commercially prepared lid scrub solution recommended by your optometrist.
• Close one eye and using a clean wash cloth (a different one for each eye), rub the solution back and forth across the eyelashes and the edge of the eyelid.
• Rinse with clear, cool water.
• Repeat with the other eye.

Conjunctivitis

Conjunctivitis is an inflammation of the conjunctiva, the thin, transparent layer that lines the inner eyelid and covers the white part of the eye.

The three main types of conjunctivitis are infectious, allergic and chemical. The infectious type, commonly called "pink eye," is caused by a contagious virus or bacteria. Your body's allergies to pollen, cosmetics, animals or fabrics often bring on allergic conjunctivitis. And, irritants like air pollution, noxious fumes and chlorine in swimming pools may produce the chemical form.

Common symptoms of conjunctivitis are red watery eyes, inflamed inner eyelids, blurred vision, a scratchy feeling in the eyes and, sometimes, a puslike or watery discharge. Conjunctivitis can sometimes develop into something that can harm vision so you should see your optometrist promptly for diagnosis and treatment.

A good way to treat allergic or chemical conjunctivitis is to avoid the cause. If that does not work, prescription or over-the-counter eye drops may relieve discomfort. Infectious conjunctivitis, caused by bacteria, can be treated with antibiotic eye drops. Other forms, caused by viruses, cannot be treated with antibiotics. They must be fought off by your body's immune system.

To control the spread of infectious conjunctivitis, you should keep your hands away from your eyes, thoroughly wash your hands before applying eye medications and do not share towels, washcloths, cosmetics or eye drops with others.