Glossary

We try very hard to avoid using too much jargon but looking after your eyes is a complicated business. You can always ask us what a word means and we’re always delighted to explain what we’re looking for and why but for the rare occasion you need to look up an optically related term we’ve included this handy glossary.

Anisometropia

Where the two eyes do not focus well together because of a difference between them, for example one being much more long-sighted or short-sighted than the other. Anisometropia can be corrected with some spectacle lenses, although contact lenses are even better at balancing the images seen by the two eyes so they can work together properly.

Anti-glare/anti-reflection/MAR coatings

Anti-reflection coatings stop light reflecting off a lens surface, so the wearer is not bothered by glare coming through the lens, or from light bouncing off the back surface and into the eye. MAR assists vision in all sorts of tasks including computer work, reading and driving. MAR coatings also make glasses much better cosmetically as you can see the person’s eyes rather than the lenses, and they don’t look as thick!

Astigmatism

Astigmatism means the sight is less clear than it could be at all distances. It is basically a distortion in the eye’s focus caused by an irregular cornea or crystalline lens; often described as having ‘rugby ball’ shaped eyes rather than round ones. Most of us have a little bit of astigmatism but glasses or contact lenses help when there is enough to cause strain. You can have astigmatism with long-sight, short-sight or on its own!

Bifocal lenses

Bifocal lenses are divided into two sections – usually a ‘distance’ focussed section at the top and a ‘reading’ segment at the bottom. Reading segments can come in all shapes and sizes and we can incorporate different prescriptions into bifocals such as ‘work-specific’ computer and reading lenses. They can be very useful but are limited to two focal lengths, and aren’t advisable if you’re unsteady on your feet or if you have a large difference between the two eyes (anisometropia).

Blepharitis

Blepharitis is a very common problem and causes (sometimes microscopic) sticky or flaky deposits to build up in the eyelashes, irritating the eye surface and making you more prone to eye infections. It often goes hand-in-hand with Meibomian Gland Dysfunction: a blockage of the tiny oil glands along the edge of the eyelid. Simple bathing and cleansing treatments can help a lot, but it is important they are done regularly to keep the condition at bay. Blepharitis can feel very uncomfortable and similar to a dry eye, or sometimes gives no symptoms at all! With assessment we can fully advise on what preventative treatments may be suitable for you and work out whether it definitely is blepharitis you’re experiencing or whether there are other underlying issues.

Cataract

As the eye ages the focussing lens inside becomes thicker, and eventually starts to become cloudy – this is known as a cataract. Cataract causes your vision to become more misty and less detailed and glare can be a problem, so often driving in difficult conditions can be unpleasant (such as facing oncoming headlights).

Cataracts can be quite slow to progress so sometimes people don’t really notice the changes happening and their sense of colour can change quite dramatically; Monet’s paintings, for example, became much yellower in later years! Cataract can be treated very successfully in most cases – in fact it is now the most commonly performed operation in the UK.

Gone are the days of waiting for the cataract to become ‘ripe’ – modern keyhole surgical techniques allow the operation to be performed much earlier, so as soon as your vision starts to become adversely affected by cataract we can refer you to assess whether an operation may be beneficial. Most people who have had cataract surgery see well straight away and don’t
even require stitches, just drops for a few weeks to help the eye settle. Although it happens to most of us, the onset of cataract can be slowed using well-fitting good quality UV protective sunglasses, eating and exercising well, and not smoking. Certain medications and medical conditions can cause cataract to form more rapidly; we may monitor you more closely if we feel it is necessary.

Colour vision & Colour-blind

Red/green colour vision deficiencies are the most common type of ‘colour-blindness’. To be completely colour-blind (monochromatic) is extremely rare and usually accompanies other vision and medical problems. Usually it is just a case of finding subtle shades of colour hard to distinguish, such as browns and purples. Testing colour vision can help us advise whether certain careers might be a problem (e.g. electricians and pilots). Interestingly, boys are much more likely to have a red/green colour deficiency than girls! If you suspect your perception of colours has changed this could be an indication of cataract or problems with the optic nerve, so it’s worth getting tested as soon as possible.

Coloured overlays, Irlen lenses and dyslexia

Some people with dyslexia are thought to suffer from what is known as ‘pattern glare’ – reading black words on a white background can confuse the brain making letters difficult to distinguish. Coloured overlays and spectacles have been found to help in a small minority of cases, but proper assessment with a trained professional is essential to make sure the right colour is prescribed. We are hoping to introduce dyslexic vision assessments in the near future but are not offering this service at present, however a thorough eye examination is the best place to start as even small uncorrected prescriptions can really help with reading.

Computer Vision Syndrome, DSE & VDU

It is important to have regular eye examinations if you use a computer screen a lot of the time. Whilst computers don’t damage the eyes they can cause strain and fatigue, as well as dry-eyes. Employers are required to pay for your eye examination if you are defined as a VDU user. The Display Screen Equipment regulations provide more detail on this, and your company’s HR department can also advise you as to what they will cover.

Conjunctivitis

There are many types of conjunctivitis: viral, bacterial and allergic are the most common types and can range from a mild pinkness and watering through to very puffy, sticky, bright red eyes! If you have red eyes that are not painful or light sensitive, and your vision is normal, the chances are it will clear up by itself in a few days. If you have any other symptoms at all or if it doesn’t clear within 5 days, it is very important that you seek a professional opinion from your Optometrist, as more serious & potentially sight-threatening conditions such as Iritis and corneal ulcers can look very similar. We don’t recommend using antibiotic eyedrops without consulting an eyecare professional first (they are ineffective for many red-eye conditions including a lot of cases of conjunctivitis). We are happy to offer advice but prefer to see you in person.

Cornea

The cornea is a clear dome that covers the iris and pupil, and is responsible for most of the eye’s ability to focus light on the retina. In laser surgery, the shape of the cornea is changed to alter how the eye focuses. The cornea can become damaged through injuries and eye diseases, causing very hazy vision. One of our main priorities with contact lens wear is to keep your corneas healthy and perfectly transparent (a contact lens sits over the cornea), so we always take a good look at them when you come for a contact lens check to make sure it all looks ok! Your corneas can reveal quite a lot about your general health, becoming inflamed with certain illnesses, dry with some medical conditions, building up deposits with various drugs and even pointing to excessive cholesterol levels!

Crystalline lens

This is the focussing lens inside the eye, which gradually loses elasticity with age causing presbyopia (a loss of near focus). As we get older, cataracts can form – a cataract is basically a thickened and hazy lens. Sometimes certain medical conditions and drugs can cause changes in the lens, so we take a look through the lens during your eye examination to see if there are signs of any changes.

Daily disposables

These are single-use contact lenses which must be thrown away after a day’s wear. They should be comfortable and provide a low risk of infection because they’re only used once; however they tend to be made in a more limited range of prescriptions especially if you have high astigmatism.

Diabetic Eye Disease & Retinopathy

There is, unfortunately, no such thing as ‘mild’ diabetes – all diabetics are at risk of eye complications. Diabetes can cause changes in the blood vessels at the back of the eye, leading to bleeds and fluid leakage which can go on to blur and distort sight if not kept in check. Good diabetic control is essential to keeping eyes healthy, and with regular eye examinations we can pick up these changes in the earliest stages and arrange for your GP to review your control, or arrange for hospital assessment and preventative treatment if necessary. Most diabetics do have an annual retinal screening examination, however we also monitor for any other changes in the eye (for example diabetic screening does not look for glaucoma) and signs of complications not found during the standard screening. As screening is usually carried out by taking a photograph of the central retina, we can pick up much more detail using our OCT scanner, so this is highly recommended for diabetics.

Double Vision ‘Diplopia’

Double vision can be caused by a cataract but is more commonly due to the eye muscles failing to work together properly. Some people wear corrective ‘prism’ lenses to help control double vision; these are slightly thicker on one side but this is usually invisible except with very powerful prisms. If ever you suddenly develop double vision you must see an eye care professional immediately as this can sometimes be a sign of serious underlying health problems, such as stroke and aneurysm.

Dispensing Optician

Registered Dispensing Opticians study for a minimum of 3 years to obtain their qualification and register with F.O.D.O. or A.B.D.O. They are fully trained in Ophthalmic Lenses and the ‘science of vision’ so know exactly what they are talking about when discussing your prescription and the implications of various lenses. We always recommend your spectacle dispensing is with a registered D.O. to ensure an accurate fit, optically correct lenses and to avoid problems that can be caused by ill-fitting or ill-measured frames and lenses.

Drivewear lenses

Drivewear lenses adapt to different light conditions by altering the depth of tint on the lens making them perfect for – you guessed it – drivers. This can increase comfort and visual performance when driving.

Dry Eye

Oddly enough, one of the main symptoms of dry eye is watery eyes! They can also feel gritty, tired, or ‘like there is something in’ the eye. Many of us experience dry eye for a variety of reasons, and can go through phases of it improving and worsening. Lots of screen work and reading causes dry eye through lack of blinking, and modern environments can be very drying (think of air conditioning and car ventilation). Lubricant drops can be used to help but it is important to work out whether it is just dry eye causing your symptoms, or anything else. Our Optometrists can examine the surface of the eye very closely to work out what’s causing your symptoms and what might help!

Glaucoma

It is a sad fact that even today, there are people unknowingly losing their eyesight when in many cases this could be prevented by having regular Eye Examinations.

Glaucoma is commonly the cause: because glaucoma is slow, progressive damage to the optic nerve, and usually has no symptoms, glaucoma patients often don’t realise they have a problem with their sight until about 50% of their useful field of vision has been irreversibly lost. Glaucoma is not always due to high pressure in the eyes but sometimes this is a factor. There is currently no way of predicting who will develop glaucoma, although we do know that a family history of the disease makes it more likely. Regular Eye Examinations can detect it in the very early stages and now OCT can help pick it up even earlier.

The good news is that Glaucoma is preventable if caught early – it is usually treated by using drops to lower the pressure in the eye to protect the nerve.

Very occasionally people experience what is known as ‘Closed Angle’ or ‘Acute’ Glaucoma. This is intensely painful and causes the eye to become very red, often causing blurred vision and ‘halos’ around lights. It is an emergency as sight loss can result very quickly if untreated, so if you suspect you may have it please attend the nearest hospital emergency department immediately.

High-Index

High-index lenses are made of special, denser materials that make them thinner and lighter than standard spectacle lenses. They’re tougher too so we often use them in rimless and supra frames. The are great for higher prescriptions and make glasses much more attractive and comfortable!

Keratoconus

Keratoconus is a progressive condition that causes the cornea to steepen and become ‘cone’ shaped rather than round; it causes high levels of astigmatism and distortion in the vision. It is more common in males and those who suffer with ‘atopic’ conditions such as asthma, eczema, hayfever and allergies. It can be detected during a normal eye examination and our Optometrists can advise on the best course of action; often contact lenses can be very helpful.

Laser surgery

Laser surgery is very successful for a lot of people with myopia, astigmatism, and some long-sighted prescriptions. If you are considering laser surgery our Optometrists are happy to advise on the basic pros and cons, but we do recommend visiting several laser clinics to make sure you have all the facts and feel comfortable with your treatment, rather than looking at headline ‘deals’. We can give you an idea of your likely standard of vision post-laser by fitting you with contact lenses to try for a few months before you take the plunge!

Lazy Eye (Amblyopia)

Some people are unable to see as well with one eye as the other, even with glasses. This can happen because of damage to the optic nerve or retina, or because one eye simply hasn’t ‘learned’ to see as well as the other. People with a lazy eye don’t often have any outward signs, as the other eye copes very well, but they don’t have good 3D vision ‘stereopsis’ so can struggle with certain tasks like catching a ball and judging distances. Lazy eye can be prevented in childhood in many cases, if it’s caught early enough. Glasses and sometimes temporary patching of the good eye are used to encourage the weaker eye to work better. We think for most children it’s difficult (but not impossible) to improve a lazy eye beyond about the age of 7; the earlier it’s found the better the chances of restoring ‘normal’ sight.

Leukocoria

Leukocoria is a white appearance to the pupil. This can happen for several reasons but the most concerning of these is a condition called Retinoblastoma, a childhood cancer which affects infants and young children. If ever you notice your child has a white pupil (sometimes this shows best in photographs) please get them seen urgently by an eyecare professional.

Macular Degeneration (AMD)

The macula is the central part of the retina. Although it is extremely small it is responsible for all detailed ‘direct line of sight’ vision, whereas the rest of the retina deals with peripheral ‘navigational’ vision. Wear and tear in the macular area is known as macular degeneration and can happen for a variety of reasons, but very often is a consequence of the eye ageing (age-related macular degeneration or AMD). Tasks such as reading and recognising features become increasingly more difficult with macular degeneration, to varying degrees.

Most people with AMD have what is known as ‘dry AMD’, where the central retina gradually becomes damaged. Eating a diet rich in lutein-containing foods can help prevent the damage, as can using good quality UV eye protection to slow the ageing of the retina. Lutein is an antioxidant pigment found in certain foods and can be taken in supplement form.

Smoking is known to increase the risk of getting AMD enormously, so we suggest you avoid it if you want to maintain good sight in later years! We are keen to monitor people with dry AMD as it can progress to the ‘wet’ form, where vision rapidly declines due to sudden changes in the blood vessels at the back of the eye. Caught early enough, wet AMD can be prevented, so it is vital that anyone noticing sudden blurring or distortion seeks professional attention immediately. OCT can help us monitor macular degeneration much more accurately than ever before.

Monovision

People with presbyopia need two different prescriptions to allow them to see in the distance as well as seeing near things. Monovision is where we use contact lenses to focus one eye in the distance and one eye close up! It sounds very odd but works really well for a lot of our presbyopic clients.

Multifocal

Multifocals or Varifocals give a range of focus through several different distances. Multifocal contact lenses can be very useful for presbyopes who want to be largely free from glasses, but we tend to find they need extra lighting and sometimes glasses for detailed tasks as they provide good but not ‘perfect’ crystal clear vision.

Multiple Sclerosis

One of the first signs of M.S. is usually damage to the optic nerve, which can cause blurring, changes to colour vision and things generally feeling ‘not right’. Optic nerve damage can be picked up during a routine eye examination and is much more easily detected with OCT scans. Anybody suffering with M.S. is advised to have their eyes examined regularly to monitor any changes to the optic nerve.

OCT

OCT takes detailed scans of the Optic Nerve and Macula, to look for signs of abnormalities below the surface of the retina and accurately measure changes in the nerve tissue at the back of the eye.

Ophthalmologist

Ophthalmologists are medically trained ‘eye doctors’ – they qualify as a Doctor and then train to specialise in eye surgery and medicine. If we find anything unusual during your eye examination we can refer you to an Ophthalmologist for a specialist opinion and treatment if necessary.

Optic Nerve

The optic nerve is the ‘wiring’ of the eye, transferring everything the eye detects to the brain so we can see it!

Damage to the optic nerve causes loss of vision, and this can happen due to inflammation, injury or diseases such as glaucoma and M.S.

Photochromic

Photochromic lenses change colour with UV light and heat. Traditionally they stay clear indoors and darken outdoors, but we can now supply lenses which have the ability to darken behind a windscreen too!

Polarised

Polarised lenses cut out glare to provide exceptionally clear & dazzle-free vision. This makes driving in the sun much safer and can even help you see ‘through’ water, so they’re perfect for fishing and sailing!

Polycarbonate

Polycarbonate lenses are tougher than normal plastic lenses and ‘shatterproof’, so are ideal for safety glasses and glasses that may take a lot of rough & tumble! We often use them in rimless and supra frames to stop the lenses chipping on the edge.

Red eye

A red eye can occur for a variety of reasons, some very serious and some very minor. The degree of redness doesn’t always tell you how serious it is! If your eye is also painful, blurred or light-sensitive (photophobic) seek a professional opinion straight away. It is red with no other symptoms and not clearing by itself in a few days, again see your Optometrist to get to the bottom of the problem.

Retina

The retina is the light-sensitive layer of tissue, lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera.

Retinoblastoma

Leukocoria is a white appearance to the pupil. This can happen for several reasons but the most concerning of these is a condition called Retinoblastoma, a childhood cancer which affects infants and young children. If ever you notice your child has a white pupil (sometimes this shows best in photographs) please get them seen urgently by an eyecare professional.

RGP (rigid gas permeable)

These are small, rigid contact lenses which give very good vision and a low risk of infection (although they still need to be looked after properly). They can feel a bit uncomfortable when they are first tried but this settles down within a few hours as the eye gets used to wearing the lens.

Rimless

Rimless frames are super-light and comfortable to wear. We have a large range and the great thing about them is because they have no frame round the lenses, we can alter the lens size or shape to suit you!

S Series

These are just-launched ‘new-generation’ varifocals which we’re promised are the easiest varifocals to get on with, ever! They eliminate the problems experienced by varifocal wearers in the past, so there’s no ‘swimming’ feeling and they give great clarity of vision across the lens. If you’ve ever been put off trying varifocals through a bad experience, give them a go – we can exchange them if you don’t like them so there’s nothing to lose!

Silicone hydrogel

We choose to fit silicone hydrogel contact lenses for most of our soft contact lens clients these days. We think they’re far better than standard soft contact lenses, and we want to keep your eyes healthy and comfortable for as long as possible! They are extremely breathable, so don’t deprive the cornea of vital oxygen needed to protect and repair itself. They’re very comfortable, great for people with dry eyes (even some who have been told they can’t wear contact lenses because of dry eye!), and have even been known to make eyes look whiter! Some are safe for extended or overnight wear; we don’t usually recommend this but are happy to consider it and discuss the pros and cons with you if you’re really keen!

Stereopsis or 3D vision

Good 3D vision comes from having two eyes that work well together – so people with a lazy eye are usually unable to do ‘magic eye’ optical illusions or see 3D TV screens well because they’re using only one eye to its full potential. If for any reason the eye muscles aren’t working properly, even people with two ‘good’ eyes will lose some depth perception – glasses help to balance all the eye muscles to make your 3D vision as good as possible!

Supra

Supra frames are ‘semi-rimless’, usually with a frame at the top and an ‘invisible’ nylon cord holding the lens below. There are all sorts of newer designs now creating some stunning-looking frames!

Titanium

Titanium is extremely light yet flexible and strong, meaning we can make very thin and lightweight frames that are (almost!) indestructible! Titanium is hypoallergenic so is also perfect for anyone who is sensitive to other metals.

Transitions

See ‘photochromic’.

Varifocal lenses

Varifocals allow you to see at a full range of distances, so with no visible line on the lens (unlike a bifocal) you can see clearly all the way through from driving to TV, computers, reading and fine close work. They had a reputation in the past for being difficult to get on with, but now with modern Varifocals such as the revolutionary S-Series, most people have no problems whatsoever! Varifocals must fit very precisely so the Dispensing Optician performs several measurements and fits them carefully to make sure the lens sits in the right place.