Keratoconus

"Keratoconus is a vision disorder that occurs when the normally round cornea becomes thin and irregularly cone shaped. This abnormal shape prevents the light entering the eye from being focused correctly on the retina and causes distortion/blurring of vision.

In its earliest stages, keratoconus causes slight blurring and distortion of vision and increased sensitivity to glare and light. These symptoms usually appear in the late teens or late twenties. Keratoconus may progress for 10-20 years and then slow in its progression. Each eye may be affected differently. As keratoconus progresses, the cornea bulges more and vision may become more distorted. In a small number of cases, the cornea will swell and cause a sudden and significant decrease in vision. The swelling occurs when the strain of the cornea's protruding cone-like shape causes a tiny crack to develop. The swelling may last for weeks or months as the crack heals and is gradually replaced by scar tissue. If this sudden swelling does occur, your doctor can prescribe eyedrops for temporary relief, but there are no medicines that can prevent the disorder from progressing.

Eyeglasses or soft contact lenses may be used to correct the mild near sightedness and astigmatism that is caused by the early stages for keratoconus. As the disorder progresses and cornea continues to thin and change shape, rigid gas permeable contact lenses can be prescribed to correct vision adequately. In most cases, this is adequate. The contact lenses must be carefully fitted, and frequent check-ups and lens changes may be needed to achieve and maintain good vision.

In a few cases, a corneal transplant is necessary. However, even after a corneal transplant, eyeglasses or contact lenses are often still needed to correct vision."

Why wear Photochromic Lenses ?

"Photochromic lenses offer great flexibility to anyone needing prescription eye wear, protecting the eyes indoors and out at all times. They are made in your normal prescription so your spectacles will correct your vision and give UV protection. Photochromic lenses meet all your various needs by combining the benefits of prescription spectacles / and sunglasses."

Photochromic Lenses

"Photchromic lenses are sometimes referred to as transition lenses, reactalite lenses or sunsensor lenses.
Photochromic lenses darken on exposure to sunlight and protect the eyes from ultraviolet radiation. Excessive exposure can cause permanent damage to the cornea and conjunctiva. Good photochromic lenses block out 100% of the most harmful rays of the sun, 100% of the time, adapting to changes in light and darkening in seconds.

Whilst sunglasses give comfort in very bright conditions by reducing the total amount of light and glare reaching the eye, they are not always convenient in changing light conditions and care must be taken that they meet Standard BS 2724 otherwise they won’t protect the eye from the sun’s damaging ultraviolet rays. In fact, non-UV absorbing lenses can do more harm than not wearing any protection at all because, behind a dark tint, the pupil increases in size allowing the harmful rays through."

Treatment For Squint

"Treatment varies accordingly to the type of squint. An operation is not always needed. The main forms of treatment are:

• Spectacles - to correct any sight problems, especially long sight.
• Occlusion - patching the good eye to encourage the weaker eye to be used. This is usually done under the supervision of an orthoptist.
• Eye drops - certain types of squint can be treated with the use of special eye drops.
• Surgery - this is used with congenital squints, together with other forms of treatment in older children, if needed. Surgery can be performed as early as a few months of age."

What Causes A Squint

"There are several types of squint. The cause is not always known, but some children are more likely to develop it than others. Among the possible causes are the following:


Congenital squint
Sometimes a baby is born with a squint, although it may not be obvious for a few weeks. In about half of such cases, there is a family history of squint or the need for spectacles. The eye muscles are usually at fault. If squint is suspected, it is important that the baby be referred for accurate assessment at the earliest opportunity. Sometimes a baby has what is known as ‘pseudo squint’ which is related to the shape of the face and this does not require any treatment, but a baby with a true squint will not grow out of it and requires careful assessment and due treatment.

Long sight (hypermetropia)
Long sightedness can sometimes lead to a squint developing as the eyes ‘over-focus’ in order to see clearly. In an attempt to avoid double vision, the brain may automatically respond by ‘switching off’ the image from one eye and turning the eye to avoid using it. If left untreated, a ‘lazy eye’ (amblyopia) may result. The most common age for this type of squint to start is between ten months and two years, but it can occur up to the age of five years. It is usually first noticed when a baby is looking at a toy, or at a later age when a child is is concentrating on close work, such as reading.

Childhood illnesses
Squint may develop following an illness such as measles or chickenpox. This may mean that a tendency to squint has been present but, prior to the illness, the child was able to keep his or her eye straight.

Nerve damage
In some cases a difficult delivery of a baby or illness damaging a nerve can lead to a squint."

Squint

"A squint (also known as a strabismus) is a condition that arises because of an incorrect balance of the muscles that move the eyes, faulty nerve signals to the eye muscles and focusing faults (usually long sight). If these are out of balance, the eye may turn in (converge), turn out (diverge) or sometimes turn up or down, preventing the eyes from working properly together.
Squint can occur at any age. A baby can be born with a squint or develop one soon after birth. Around 5 - 8% of children are affected by a squint or a squint-related condition, which means one or two in every group of 30 children. If a child appears to have a squint at any age from six weeks onwards, it is important to seek professional advice quickly. Many children with squints have poor vision in the affected eye. If treatment is needed, the sooner it is started the better the results.
Squint can be a complex condition and not every situation is covered here. Your optometrist will be pleased to give further advice, if needed. Children will benefit from support and encouragement during treatment and you should not be afraid to ask questions which will help you understand the condition. The successful outcome of treatment depends upon everyone co-operating."

High-index and aspheric lenses

"If you need high-powered lenses you can improve the weight or appearance of your glasses with special lens materials and designs. High-index lens materials and aspheric designs mean that lenses can now be made thinner, lighter and better looking than traditional lens types. High-index materials and aspheric lens design make lenses for short sight and long sight thinner and allows more optimal vision through the lens area away from the centre of the lens"

Prescription Sunglasses

"Whatever your prescription, it is important to protect the eyes against excessive ultraviolet (UV) radiation. Protection is needed to avoid reflected light from sand and snow or if you spend long periods outdoors, particularly in the summer. Prescription sunglasses can be made with single-vision, bifocal or varifocal designs to offer the same standard of protection as non-prescription sunglasses. Only costs an extra £10 (online price, may cost a lot more on the high street) for having the sunglass tint put on the glasses, worth while in the long term"

Scratch-resistant / hard coating

"Plastic lenses are lighter than traditional glass lenses but they scratch more easily. Scratched lenses can be irritating for the wearer and look unsightly. Scratch-resistant coatings are available to protect against damage and prolong lens life."

Anti-Reflection Coating

"Spectacle lenses can be provided with anti-reflection coatings which virtually eliminate distracting reflections off the lens surfaces. Reducing reflected light is particularly helpful for computer users and for night driving. Anti-reflection coatings also improve the cosmetic appearance of your glasses and can make thick lenses look thinner."

Varifocal Lenses

"Varifocal lenses, also known as progressive lenses, are used for correcting presbyopia but unlike bifocal lenses, varifocals have no visible dividing lines between the different corrections. Instead they have a graduated section in which the power of the lens progresses smoothly from one prescription to the other, allowing the wearer to see clearly at all distances. These lenses also have the benefit of looking better - they don't draw attention to the ageing process. A range of varifocal designs is available depending on your lifestyle and occupation. Modern lens technology means that there are many different designs and materials to choose from. Your optometrists or dispensing optician will be able to advise you on the best lenses to suit your individual requirements."

Bifocal Lenses

"Bifocal lenses contain two optical corrections with a distinct dividing line between the two parts. The most common use of bifocals is for people who have become presbyopic and need a different prescription for close work. The upper part of the lens corrects distance vision and the lower half is for near vision. Trifocals are also available that have three sections and incorporate a correction for intermediate vision. Bifocals and trifocals come in a range of designs. Bifocals or varifocals are more commonly prescribed than trifocals"

Single Vision Lenses

"The simplest form of spectacle or contact lens is the single-vision lens, made to a single prescription to correct a particular eyesight problem. Concave lenses are used to correct short sight and convex lenses to correct long sight. Concave lenses are generally thinner in the centre than they are at the edge and convex lenses are usually thinner at the edge than at the centre. The curvature of the lens, its thickness and weight will depend on the amount of long or short sight it is designed to correct. The lens material will also influence the thickness and weight of your lenses, as will the size and shape of the spectacle frames you choose. Traditionally, spectacle lenses were made of glass but most lenses are now lightweight plastic (1.5 cr39) and there is a wide range of materials available to suit your prescription and lifestyle."

Protection From UV radiation

"Ultraviolet radiation reaches the eyes not only from the sky above but also by reflection from the ground, especially water, snow, sand and other bright surfaces. Protection from sunlight can be obtained by using both a brimmed hat or cap and UV absorbing eyewear.

A wide-brimmed hat or cap will block roughly 50 per cent of UV radiation and reduces UV that may enter above or around the glasses. Ultraviolet absorbing eyewear provides the greatest measure of UV protection.

It is prudent to protect the eyes of children against UV radiation by wearing a brimmed hat or cap and sunglasses. Sunglasses for children should have lenses made of plastic rather than glass for added impact protection.

Ideally, all types of eyewear including prescription spectacles, contact lenses and intraocular lens implants should absorb the entire UV spectrum (UV-A and UV-B). UV absorption can be incorporated into nearly all optical materials currently in use, its inexpensive, and does not interfere with vision. The degree of UV protection is not related to price. Polarisation or photosensitive darkening are additional sunglass features that are useful for certain visual situations, at the same time providing UV protection.

For outdoor use in the bright sun, sunglasses that absorb 99-100 per cent of the full UV spectrum to 400 nm are recommended. Additional protection for the retina can be provided by lenses that reduce the transmission of violet/blue light.

Such lenses should not be so coloured as to affect perception of the colour of objects, such as traffic signals. The visible spectrum should be reduced to a comfortable level to eliminate glare and squinting. Individuals who also wear clear prescription eyewear outdoors should consider using lenses which absorb 99-100 per cent of the UV radiation to 380-400 nm."

Ultraviolet & the eye

"Ultraviolet (UV) radiation comprises invisible high energy rays from the sun that lie just beyond the blue end of the visible spectrum.

More than 99% of UV radiation is absorbed by the anterior structures of the eye, although some of it does reach the light-sensitive retina (back of the eye). The UV radiation present in sunlight is not useful for vision. There are good scientific reasons to be concerned that UV absorption by the eye may contribute to age-related changes in the eye and a number of serious eye diseases.

Protection can be achieved by simple, safe and inexpensive methods such as wearing a brimmed hat and using eyewear that absorbs UV radiation (sunglasses, including prescription sunglasses/reactolite lenses)."

Opticians 'seeing 1,000pc profit on glasses'

An interesting piece found in the daily mail..................

"High Street opticians are making profits of more than 1,000 per cent on glasses, it has been claimed.

A recent Government study found that the sale of spectacles is the one area where deregulation and the supposed introduction of greater competition has failed to drive down prices. In fact, the average price paid for a pair is now put at £148.50 - up by around 40 per cent since 1999.

The industry is dominated by four major chains, Boots, Vision Express, Specsavers and Dollond & Aitchison, which are responsible for more than 70 per cent of sales.

It is claimed there is little evidence of price competition - except around promotional periods such as January.

The public is largely kept in the dark about the true cost of frames and lenses, which means they are unable to challenge charges. And there is little or no value in shopping around because prices across the major High Street names, and even small independent opticians, are about the same."

Presbyopia - Cause / Treatment

"Presbyopia is caused by an age-related process. This is different from astigmatism, myopia and hypermetropia, which are related to the shape of the eyeball and caused by genetic factors, disease, or trauma. Presbyopia is generally believed to stem from a gradual loss of flexibility in the natural lens inside your eye.
These age-related changes occur within the proteins in the lens, making the lens harder and less elastic with the years. Age-related changes also take place in the muscle fibers surrounding the lens. With less elasticity, the eye has a harder time focusing up close. Other, less popular theories exist as well.

Presbyopia is commonly corrected via prescription glasses (single vision reading glasses, bifocals or varifocals), contact lenses (not a common approach with presbyopia)

Consult your Optometrist for the best suited option"

Presbyopia - Reading Difficulties

"During middle age, usually beginning in the 40s, people experience blurred vision at near points, such as when reading, sewing or working at the computer. There's no getting around it — this happens to everyone at some point in life, even those who have never had a vision problem before.

When people develop presbyopia, they find they need to hold books, magazines, newspapers, menus and other reading materials further away or at arm's length in order to focus properly. When they perform near work, such as embroidery or handwriting, they may have headaches or eyestrain, or feel fatigued."

VDU's and Your Eyes - Prescription Glasses

"Only a small proportion of users will need spectacles specifically for working at a VDU and the majority of these will be what is known as presbyopic. Presbyopia affects us all as we get older. Around the age of 45 people begin to find they lose the ability to focus on objects that are close up.

Spectacles with single vision, bifocal or varifocal lenses can all be used successfully for VDU work. Contact lenses are also suitable, but wearers should try to blink regularly which keeps the lenses comfortable.

When you concentrate on the screen for long periods, your normal blinking rate slows down. Presbyopic contact lens wearers may need additional reading glasses.


Reflection-free lenses
Reflection-free lenses are well worth considering for VDU users. Because they eliminate almost all reflections VDU glare is considerably reduced, providing clearer and sharper vision."

Coloured Overlays / Coloured Glasses - Meares–Irlen syndrome

There are many factors involved. First, are the overlays obviously beneficial? If so, only a short trial period, say six weeks, is necessary, particularly if headaches have been reduced but not eliminated, and if untidy writing continues to be a problem. Under these circumstances glasses may further reduce the headaches and may well improve the handwriting.

If, on the other hand, the response to overlays is less marked, it seems sensible to see whether the child continues to use overlays without prompting for, say, a school term or longer, before considering coloured glasses. Coloured glasses are more expensive than overlays, and it may be wise to wait before incurring the cost.

Another factor to consider is the age of the child. It is often difficult to assess a child for coloured glasses below the age of 8."