Eye Diseases

What are refractive errors?

Refractive errors occur when the shape of the eye prevents light from focusing directly on the retina. Refractive errors can be caused by the length of the eyeball (longer or shorter), changes in the shape of the cornea, or aging of the lens. The most common types of refractive errors are near-sightedness (myopia), far-sightedness (hyperopia), astigmatism and presbyopia.

• Near-sightedness: This is a condition where objects up close appear clearly, while objects far away appear blurry.
• Far-sightedness: This is a common type of refractive error where distant objects may be seen more clearly than objects that are near.
• Astigmatism: Astigmatism occurs when the eye does not focus light evenly onto the retina, causing images to appear blurry and stretched out.
• Presbyopia: This is an age-related condition (often occurring from age 35 upwards) in which the ability to focus up close becomes more difficult. As the eye ages, the lens can no longer change shape enough to allow the eye to focus on close objects clearly.

What are the symptoms of refractive errors?

Blurred vision is the most common symptom of refractive errors. Other symptoms may include double vision, haziness or a glare around bright lights. Squinting, headaches and eye strain can also indicate refractive errors.

How are refractive errors diagnosed?

An eye care professional can diagnose refractive errors during a comprehensive dilated eye examination.

How are refractive errors treated?

Refractive errors can be corrected with eyeglasses, contact lenses, or in some cases surgery. Eyeglasses are the simplest and safest way to fix refractive errors. Your eye care professional can prescribe appropriate lenses to correct your refractive error and give you optimal vision. Contact lenses work by becoming the first refractive surface for light rays entering the eye, causing a more precise refraction or focus. They are also a safe and effective option if fitted and used properly. However, if you have certain eye conditions you may not be able to wear contact lenses.

Surgery for refractive errors aims to change the shape of the cornea permanently. This change in eye shape improves vision by allowing the light rays to focus precisely on the retina. There are various types of refractive surgeries. Your eye care professional can help you decide if surgery is an option for you.

What is Age-Related Macular Degeneration?

Age-related macular degeneration (AMD) is a common eye condition among people as they age. In fact, Vision Australia ranks AMD the leading cause of severe vision impairment in people aged over 40 years in Australia.

This condition gradually destroys the macula, the part of the eye that provides sharp, central vision needed for seeing objects clearly. The vision loss makes it difficult to recognise faces, and to do daily tasks such as reading and driving.

There are two types of AMD, described as either dry or wet. The following is a brief description of each:

• Dry AMD: According to the Centers for Disease Control and Prevention , dry AMD is more common and accounts for 70–90% of cases of AMD. This form results in a gradual loss of central vision.
• Wet AMD: Wet AMD is rarer, more severe and leads to sudden and significant changes in vision. It happens when new blood vessels under the macula leak blood and fluid. All people who have the wet form had the dry form first.

What are the symptoms of AMD?

Dry AMD has few symptoms in the early stages. One of the most common early signs of dry AMD is drusen, tiny yellow or white deposits under the retina. In the later stages, blurred vision and a gradual decline in the ability to see objects clearly can occur. Objects also may not appear to be as bright as they used to be. An early symptom of wet AMD is that straight lines appear wavy. People with wet AMD may also develop dark or empty spaces blocking the central field of vision.

How is AMD diagnosed?

The early and intermediate stages of AMD usually start without symptoms. Only a comprehensive dilated eye exam can detect AMD.

How can AMD be treated?

There is currently no treatment for dry AMD but treatments are available for wet AMD that are aimed at maintaining the vision for as long as possible. The main treatment for wet AMD is Lucentis injections. The injections aim to reduce the progression of the disease and further loss of vision by preventing the growth of new abnormal blood vessels in the retina. Photodynamic therapy and laser surgery may also be used to treat AMD, however these treatment are less common.

What are cataracts?

A cataract is a clouding of the eye's natural lens. While cataracts most commonly occur in those who are older, they can be present at birth and develop at any age due to a variety of causes. Types of cataracts include:

• Subcapsular cataract: This occurs at the back of the lens. People with diabetes or those taking high doses of steroid medications have a greater risk of developing a subcapsular cataract.
• Nuclear cataract: This type forms deep in the central zone of the lens, called the nucleus. Nuclear cataracts are typically associated with aging.
• Cortical cataract: This type of cataract occurs in the lens cortex, which is the part of the lens that surrounds the central nucleus.

What are the symptoms of cataracts?

A cataract starts out small and at first has little effect on your vision. You may notice that your vision is blurred a little, like looking through a cloudy piece of glass. Other common symptons include weaker vision at night and colours appearing faded or yellowed. A cataract may cause light from the sun or automobile headlights to feel blinding or uncomfortable glary. When a nuclear cataract first develops, it can bring about a temporary improvement in your near vision, called ‘second sight’. Unfortunately, the improved vision is short-lived and will disappear as the cataract worsens.

How are cataracts diagnosed?

An eye care professional can diagnose cataracts during a comprehensive dilated eye examination.

Can cataracts be treated?

When symptoms begin to appear, vision may be corrected with a change in prescription eyeglasses, bifocals or contact lenses. If your vision loss cannot be corrected with new glasses and cataracts interfere with your daily life, you may be a candidate for cataract surgery, which involves removing the clouded lens and replacing it with a clear, artificial one. Cataract surgery is often very successful in restoring vision.

What is glaucoma?

Glaucoma refers to a group of eye diseases that can damage the optic nerve, which carries information from the eye to the brain. In most cases, glaucoma is associated with higher-than-normal pressure inside the eye. If untreated or uncontrolled, glaucoma first causes peripheral vision loss and eventually can lead to blindness.

There are two major categories of glaucoma, ‘open angle’ and ‘closed angle’. Open angle, is a chronic condition that progresses slowly over a long period of time without the person noticing vision loss until the disease is very advanced and has caused significant damage.  Angle closure can appear suddenly and is accompanied by severe pain. While visual loss can progress quickly with angle closure glaucoma, the pain and discomfort usually leads patients to seek medical attention before permanent damage occurs.

What are the symptoms of glaucoma?

Glaucoma is often called the "silent thief of sight", because most types typically produce no symptoms until noticeable vision loss occurs. For this reason, glaucoma often progresses undetected until the optic nerve has already been irreversibly damaged, with varying degrees of permanent vision loss.

However, with angle-closure type of glaucoma, symptoms include the sudden onset of severe throbbing eye pain, headaches, blurred vision, rainbow halos around lights, redness in the eye, nausea and vomiting. If you have these symptoms, make sure you see an eye care practitioner or visit the emergency room immediately so steps can be taken to prevent permanent vision loss.

How is glaucoma diagnosed?

Glaucoma is detected through a comprehensive dilated eye exam conducted by an eye care specialist.

Can glaucoma be treated?

Depending on the severity, glaucoma can be treated with medication, laser treatment or surgery. Eye drops with medication aimed at lowering eye pressure usually are tried first to control glaucoma. Early detection and treatment of this condition can prevent or delay vision loss.