Sometimes vision impairments only affect one eye and there are many reasons why this might be the case. Here are a several issues that may affect only one eye.

Why do I see patterns in one eye?

There are a few reasons why this could happen, but it is usually nothing to worry about, particularly if it resolves itself after you wake up. However, if you are concerned about this, you should have your eyes examined by an optometrist and see your GP for a general check up.

What are vitreous floaters?

If you notice any dark specks, spots, clumps, threads, or dots in your vision they could be vitreous floaters. These are mostly harmless, and are part of the vitreous humour. This is a jelly-like substance in the eyeball and as we age, tiny clumps form and appear in your vision. As this moves with your eye, it explains why the floaters often seem to disappear. However, if you begin to notice a sudden increase of these floaters in your vision, it may indicate damage or disease, so it is best to visit your optometrist for a check up.

Why is one eye stronger than the other?

If there is a huge difference in your prescriptions, it could mean that one of your eyes is 'lazy' and was not able to develop properly when you were a child. The scientific term for this is amblyopia. This can be resolved somewhat by the use of corrective lenses as an adult, but you may find that vision in your lazy eye is never as good as in your other eye.If the condition is picked up in children, it can be reversed with early treatment including using an eye patch so that the weaker eye can be encouraged to develop properly. However, if you think the problem is getting worse it could indicate a refractive problem, rather than being a problem with the health of your eyes. This means it is important to have regular eye tests and keep up with any prescription changes.

Why have I lost sight in one eye?

If you experience sudden blindness whether it is in one eye or both, it is important to seek immediate medical assistance as this is a medical emergency.It doesn't necessarily mean that you will lose your sight for good, but most underlying problems are serious and could even be life threatening. Sudden blindness could mean your retina is damaged or indicate a vitreous haemorrhage or brain tumour. It is essential to seek immediate help.

Why does it take longer for one eye to open in the morning than the other?

If one eye opens much more slowly, it could be that you have a weakness in one of the muscles in your eyelid. This is not uncommon. However, it could also be the result of trapping the nerve controlling the muscle in your sleep. It is advisable that you visit your optometrist for a referral to an eye specialist if you think this could be the case. Another explanation could be that it is the result of a condition called blepharitis, which can cause the eyelids to stick together. Try to keep your eyelids clean and try warm compresses on the closed eye twice a day. Lubricating eye drops could also be used in the evening to help resolve this problem. These can be purchased over the counter.

Why does one eye lose control when I focus close up and my head slant?

If you find your head slanting when you look at something close up, it could meant that you have a long standing vertical muscle imbalance between your eyes. The head slanting is a subconscious attempt to bring the eyes closer together in order to prevent double vision. If this has become worse, it is important to visit your optometrist as you may need an optical prescription or eye specialists referral to correct this condition.

Why am I having trouble seeing out of one eye and tooth problems?

The only time you would have problems with one eye and tooth problems is if one of the nerves near the side of the face has been affected. However, it you are finding it hard to see out of one eye, you should visit your optometrist for a check up.

Why is one eye worse after mild trauma?

If you experience mild trauma, it is unlikely that one eye will be affected more than the other, or that this will cause long term problems.

Could a bleed in my brain result in loss of visual fields on right side?

A bleed in your brain should not impact your prescription or corrected visual acuity needs, but could cause damage to your visual fields. Your optometrist may be able to provide more information about this and detect even smaller visual field defects using specialised equipment such as the Humphrey Vision Analyser, which is the most sensitive tool available.

Why am I having a visual field defect in one eye without any other symptoms?

The visual field is the portion of your surroundings that can be seen at one time. A visual field defect means you cannot see as much out of the corners or sides of your eyes, or from the top or bottom. There are many reasons why this occurs, from macular degeneration, cone dystrophies, macular holes and other rare conditions to glaucoma, retinal detachment, Leber's optic atrophy and retinitis pigmentosa. However, if there are no other symptoms and your eyes are otherwise healthy it may not be something serious. It is still best to visit your optometrist as soon as possible so that anything more concerning can be eliminated.