If you are planning to visit your optometrist or eye specialist, you may wonder just what some of the procedures that take place are and what is involved.Here is a guide to some of these processes.

What is the Snellen chart?

This is the name for the eye chart that your optometrist will use in order to judge how well you can see in the distance.Most versions of the Snellen chart consist of 11 rows of capital letters. These get progressively smaller as you read down the chart. If you can read the bottom row of letters it means that your visual acuity is very good and you have 20/20 vision.

What is the Near Point of Convergence?

This test is used to calculate the distance from where your eyes can work together to focus without double vision.To find out where this point is, your optometrist will hold a small target in front of you and move it closer until you have double vision or your optometrist calculates that your eyes are not focussing.

Why do I have a positive SPH correction for distance?

As people age, their long distance vision deteriorates, this is known as presbyopia.This process continues and as a result you may find you also need a positive prescription to see in the distance. Negative SPH corrections are for people with shortsightedness from a younger age.

What surgery is available for astigmatism?

Astigmatism is a refractive error where the eyeball is elongated so the light cannot be focused properly on the retina in order to form a clear vision.It can be treated with corrective glasses even if you have corneal grafts. Contact lenses are also available and refractive surgery is another option. This is known as astigmatic keratotomy surgery although it has been largely replaced by LASIK. If this is something you are interested in, it is a good idea to talk to your optometrist, as eligibility may depend on your individual circumstances.

What are the procedures for glaucoma?

If your optometrist suspects you have glaucoma during your eye examination, they may run some tests. There are five factors that need to be checked before a diagnosis is made. Your inner eye pressure may be tested using a tonometry test, the shape and colour of the optic nerve using an ophthalmoscopy, or dilated eye exam. They form part of the basis of an eye examination as they check the health of your eyes. These are a regular part of testing for glaucoma. However, if they reveal anything unusual, further tests may be run. A perimetry may be used to examine your complete field of vision, gonioscopy to determine the angle where your iris meets your cornea and pachymetry to determine the thickness of the cornea.

What are the procedures to treat early background retinopathy?

Diabetics may develop retinopathy, a disease of the retina. It can lead to poor vision and in some cases, blindness.If you have been diagnosed with early background retinopathy it is essential that you undertake regular eye examinations to monitor the condition. Retionpathy can be stable for many years, provided that your diabetes is well controlled.If retinopathy does progress there are many treatments you can have to prevent loss of vision. Talk to your optometrist for more information.

What is the treatment for a corneal scar?

A corneal scar can be caused from injury, disease or from an infection.The resulting scars can interfere with vision and distort or block light from entering the eye.A corneal transplant is the best way to treat scars that affect vision. This is successful in the majority of cases.

What is eneucleation?

Essentially this procedure is removal of the eye. It is normally done by an eye specialist to remove a tumour from your body, or to remove a blind and painful eye. With this type of surgery there is no chance that vision can be restored, but most people find they can see using ocular prosthetics and still do all the things they used to do before having surgery. The implant will move in the same way as the eye would have as it will be attached to the eye muscles.

What options are available if I need distance and near correction?

If you are suffering from age related presbyopia, or longsightedness, it can be corrected using multifocal lenses. Monovision can also be used where one eye is corrected for distance and the other for near vision so that they can work together to give you perfect vision. Surgery can also be used for the same purpose, but you will need to discuss this with your optometrist as this is not suitable for everyone. Alternatively, clarivu surgery can be used. This is a lens removal and implant surgery. A multifocal transplant will be added into your eye, helping you to see in the distance and read without glasses to some extent.

However, this is not widely available so you will need to consult with your optometrist about this.Is there a way to prove that I cannot see out of one eye?

While an eye test will indicate whether you can see out of both your eyes, there are other ways to test how your eyes function.An electroretinograph can use electrodes and stimuli to see if your nerves are connected properly. However, you will need a referral to an eye specialist for this procedure.

What are the procedures for removing a small chalazion?

A chalazion is also known as a meibomian cyst and is a lump that develops on the eyelids as a result of a blocked oil gland. While sometimes they disappear on their own or by using a hot compress treatment, other times require an excision. This will drain the cyst, without altering the shape of the eyelid or leaving a visible scar. This procedure will need to be carried out by an eye surgeon and you will need to get a referral from your optometrist first.

How is stereoscopic acuity measured?

This is measured by using the Titmus Fly Test, where two polarised images are shown at right angles to each other and viewed through polarising filters.This can measure how well your eyes see in three dimensions.

How can I improve my depth perception?

There are a few exercises you can complete to improve the way you see objects far away from you.An optometrist can show you how to do these, and explain which will work best for you.