top of page

Refractive Errors


The most common vision problems are refractive errors, which means that the image of an object you are looking at is not focussed properly on the retina (the light sensitive tissue in the back of the eye). If you suffer from blurry or uncomfortable vision, you should see a Sieff Optometrist as soon as possible. Refractive errors can usually be corrected using spectacles. The following are the four main types of refractive errors.


Commonly known as short-sightedness. This condition happens as a result your eye focussing light your eye focussing light in front of the retina, resulting in blurred vision. Short-sighted people can often see reasonably clearly at short distances, but will struggle to see distant objects clearly. Take the online eye test to see if you may be short-sighted.


Hyperopia or long-sightedness is a condition in which the optical components of the eye are not strong enough, and so light is not focussed onto the retina. This results in blurred vision that is usually worse at shorter distances. People with hyperopia often have reasonable vision in the distance, but may find that their vision is blurred or that they experience feelings of eyestrain or headaches when doing near work, such as reading. Take the online eye test to see if you may be long- sighted.



Astigmatism is a condition where the optical power of the eye varies depending on the angle of light passing through it. Astigmatism may cause blurry vision, eye strain and even headaches. It is usually due to the shape of the cornea (the front surface of the eye). If the curvature of the cornea is not the same in all directions (like the side of a rugby ball) it will bend the light passing through it by different amounts depending on the direction of the light, producing astigmatism. Take the online eye test to see if you may have astigmatism.


Presbyopia is the gradual reduction in the amount that the eye can change its focus. The changes are the result of the continued ageing of the lens and is a normal part of ageing. Presbyopia usually becomes noticeable between the ages of 40 and 50 as an inability to focus on near objects. People in this age group often find that they have to hold things further away to see them clearly. Presbyopia can be corrected by using spectacles designed for close work, such as reading glasses, bi-, tri- and multifocal lenses. Take the online eye test to see if you may need reading glasses.



About 4% of South Africans have diabetes. Of these, more than 70% will develop some changes in their eyes within 15 years of diagnosis. Optometrists play a fundamental role in diagnosing these conditions in their early stages which is also the time that your eyes will respond best to treatment.


Diabetes sometimes causes the focusing ability of the eye to weaken or to fluctuate from day to day. This characteristic has often led to optometrists detecting potential diabetes in their patients.


The problem eases when blood sugar levels are controlled. Diabetes can also cause more dangerous changes in the eyes, primarily through its effects on the blood vessels in the retina.

Eye Disorders


Eye diseases are relatively rare, although they become more common as we get older. All eye diseases should be regarded as serious – even diseases that appear to be mild can have the potential to cause serious damage if they are not treated appropriately. If you suspect that you have an eye disease see a Sieff Optometrist urgently.


Cataracts are cloudy areas that form in the lens of the eye. The lens is normally clear. Poor vision results because the cloudiness interferes with light entering the eye. The opacities in the lens scatter the light, causing hazy vision, in the same way that a dirty window scatters light. Most cataracts are a result of ageing and long-term exposure to UV light. Some are caused by injury and certain diseases and in rare cases by exposure to toxic materials. Occasionally cataracts are present at birth. Cataracts get worse if untreated and can cause blindness, so make sure you see a Sieff Optometrist if you are experiencing any of these symptoms.



Glaucoma occurs when the pressure inside the eye increases and causes nerve cells in the retina to be damaged. This, if left untreated can eventually lead to blindness. Ensure that you see a Sieff Optometrist at least once a year, especially if you’re over 40 years.

Macular Degeneration 

Predominantly found in the elderly, this disorder occurs when the centre of the inner lining of the eye, known as the macula area of the retina, suffers thinning, atrophy and in some cases, bleeding. This can result in loss of central vision, which inhibits the ability to see fine details, to read, or to recognize faces. Ensure you see a Sieff Optometrist at least once a year, if you’re over 40 years.


Also called Strabismus or lazy eye, this condition involves a lack of coordination between the extra ocular muscles that prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely affect depth perception. Strabismus can be either a disorder of the brain coordinating the eyes or a disorder of one or more muscles. Your Sieff Optometrist can assist you with this problem.

Retinitis Pigmentosa 

This is a group of inherited disorders in which abnormalities of the photoreceptors (rods and cones) or the retinal pigment epithelium (RPE) of the retina lead to progressive visual loss. Affected individuals first experience defective dark adaptation or nyctalopia (night blindness), followed by constriction of the peripheral visual field and eventually loss of central vision. If you are noticing a change in your vision at night, be sure to make an appointment with to see a Sieff optometrist.

bottom of page