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Frequently Asked Questions

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Contact Lens (7)

Contact Lens

For many people contact lenses are the ideal alternative to spectacles. For sport, special occasions or everyday wear, they are a versatile solution. Contact lenses, like eyeglasses or refractive surgery, can correct your nearsightedness, farsightedness, and astigmatism.

Types of Contact lenses?

Classified by material, there are three types of contact lenses:

Hard lenses

Keratitis

Hard Lens

These are made from PMMA — also known as Plexiglas or Lucite. These lenses are virtually obsolete and rarely used.

Soft lenses

These are by far the most commonly used lenses. They are usually made of a hydrogel polymer and fit snugly onto the cornea making them very comfortable to wear. Some soft lenses have silicone compounds added to allow oxygen permeability, thus permitting significantly increased wearing times, i.e. “Extended wear”.

Rigid Gas Permeable lenses (RGP)

These are smaller and are made from rigid, waterless plastics and initially less comfortable to wear but are especially good for presbyopia and high astigmatism. For some people they allow the sharpest vision, and their oxygen permeability allows them to worn all day. This type of lens should typically last at least a year before replacement is needed. A well known problem with RGP lenses is their tendency to temporarily change the shape of the cornea, so for those contemplating refractive surgery, the lenses may have to be left out for a couple of weeks for the cornea to recover.

From the introduction of soft lenses in 1971 until relatively recently, most lens brands have been made from “hydrogel” plastics. Recently, new silicone hydrogel contact lenses have been introduced. They have become the contact lenses of choice for many eye care practitioners, because they allow more oxygen to pass through the lens to the eye, and they are less prone to dehydration.

How long can I wear contact lenses?

Until 1979, everyone who wore contact lenses removed and cleaned them nightly. The introduction of “extended wear” enabled wearers to sleep in their contacts. Now, two types of lenses are classified by wearing time:

  • Daily wear — must be removed nightly
  • Extended wear — can be worn overnight, usually for seven days consecutively without removal

“Continuous wear” is a type of extended wear lens that can be worn for 30 consecutive nights.

What are the different types of contact lens designs?

Many lens designs are available to correct various types of vision problems:

Spherical

Sphericalcontact lenses are the typical, rounded design of contact lenses, which can correct myopia (nearsightedness) or hyperopia (farsightedness).

Toric Lenses for Astigmatism

Astigmatism is when the cornea is not perfectly spherical or round. Instead of one radius of curvature, it has two running at 90° to each other. Toric lenses allow greater visual clarity for those with astigmatism by correcting this irregularity. They are available in both soft and RGP form, though soft are by far the most commonly used.

Bifocal and Multifocal Lenses

Bifocal and multifocal contact lenses contain different zones for near and far vision to correct presbyopia, These are useful for those into their 40s and beginning to struggle with near tasks. They allow the wearer to achieve clear vision at a variety of distances.

Orthokeratology Lenses

This is more commonly used in the USA than in Britain. Special contact lenses are worn at night before going to bed and they gently mould the cornea whilst the wearer is asleep. Upon waking the lenses are removed, and the temporary cornea shape change allows clearer vision, however, the lenses must be worn every night, or alternate nights or the cornea reverts back to its original shape.

All of these lenses can be custom made for hard-to-fit eyes. Many other additional lens designs are available. Typically these are less common and fabricated for use in special situations, such as correcting for keratoconus

What Other features should I look out for?

Coloured Lenses. Many of the types of lenses described above also come in colors that can enhance the natural color of your eyes — that is, make your green eyes even greener, for example. Or these lenses can totally change the eye’s appearance, as in from brown to blue. They usually consist of a soft contact lens base with coloured iris pattern printed on top.

Special-Effect Lenses. Also called theatrical, novelty, or costume lenses, these take coloration one step further to make you look like a cat, a zombie, or another alter-ego of your choice.

Prosthetic Lenses. Colored contact lenses can also be used for more medically oriented purposes. People with disfigured eyes, as a result of accidents or disease, can use a custom, opaque colored lens to mask the disfigurement and match the appearance of their normal eye.

UV-Inhibiting Lenses. Today, many contacts incorporate an ultraviolet blocker in the lens material, to cut down on UV light that can eventually cause cataracts and other eye problems. You can’t see this blocker by looking at the lens. And since contacts don’t cover your entire eye, UV blockers cannot substitute for traditional sun protection like good quality sunglasses.

Hybrid Lenses. One brand of lenses features a GP center with a soft outer skirt, providing wearers with both the crisp optics of a rigid lens and the comfort of a larger, soft lens.

About Replacement Schemes?

This should be discussed with you by your eye care practitioner. Some lenses are manufactured with a specific wearing time, i.e. daily soft lenses, which are thrown away every day and some which will last a whole year. Replacement schedules may vary from one person to another, for example, a patient who suffers from persistent lens deposits may have to replace sooner.

What problems can contact lenses cause?

Problems may arise for a variety of reasons, but they are usually relatively easy to solve. Here are some of the basic problems:

  • Giant Papillary Conjunctivitis
    conjunctivitis

    Conjunctivitis

    This is characterised by general eye itching and contact lens intolerance. It is readily diagnosed by eversion of the upper eyelid and observing the “cobblestone” appearance underneath. It is generally thought to be due to an immune response to protein deposits on the lens surface. This can be remedied by more frequent lens changes or the use of mast cell stabilisers. Occasionally you may be advised to stop contact lens wear altogether.

  • Bacterial Corneal Ulceration
    This is a more serious problem associated with contact lens wear. There is typically pain, watering of the eye and occasionally blurred vision, depending upon the location. Diagnosis is usually made by taking a scrape of the corneal surface and identifying the pathogen. Treatment is most commonly in the form of eye drops or eye ointment. For more serious infections, permanent visual impairment may result depending upon the location of the ulcer.
  • Corneal Vascularisation
    Corneal vascularisation is fairly rare in RGP lenses and almost solely attributed to the long term wear of soft lenses. It is thought that the stimulus for these new vessels is mainly due to the cornea being starved of oxygen. It usually has no symptoms and is characterised by blood vessels gradually invading the cornea. These new vessels are generally thought to be permanent, so it is important to remedy the problem as soon as possible. Possible solutions are to reduce wearing time, fit a silicone hydrogel lens, or change to an RGP. If these solutions fail then you may be advised to stop contact lens wear altogether.
  • Corneal Oedema
    Corneal oedema or corneal swelling is caused by restricted oxygen supply to the cornea, creating raised lactic acid levels, and is most common with soft lenses and sleeping in lenses overnight. Symptoms are blurred vision, halos, contact lens intolerance and a generally red and watery eye, however occasionally there may be no symptoms at all. This can be alleviated by reducing wearing time, changing to a more permeable lens, or one with a higher water content.
  • Dry Eye
    Those with reduced or marginal tear film quality may experience dryness and a gritty feeling especially towards the end of the day. The wearing of any contact lens places extra demand upon the tear film, and it is not uncommon to have comfort problems. Aggravating factors include blepharitis and dry, air-conditioned environments. Using artificial tear lubricants appears to alleviate symptoms and for some, RGP lenses are more compatible.
  • Acanthamoeba Keratitis
    Keratitis

    Keratitis

    This is probably the most dreaded of all contact lens complications and can have devastating visual consequences. The Acanthamoeba protozoan can commonly be found in soil, tap water and hot tubs and swimming pools, and in its dormant form, is remarkably resistant to amoebicides. The infection may display a characteristic “ring form” on the cornea with extreme pain and redness. Brolene is commonly used as a treatment, but for some a combination of drugs may be necessary to control the infection. As is often the case, prevention is the best solution, so swimming with lenses and using tap water for rinsing is not advised.

As is the case with most things, prevention is the best cure and many problems can be avoided by following instructions and visiting your practitioner regularly.

Refractive Lens (14)

What is a refractive error?

Light enters the eye through the cornea (the curved clear window of the eye) and is focused on the retina. Ideally, the cornea should be perfectly dome-shaped. When it is out-of-shape, light bends (refracts) at the wrong angle and images are not focused properly. This causes them to appear blurry or distorted. Problems with the focusing power of the eye are called refractive errors.

There are three primary types of refractive errors: myopia, hyperopia, and astigmatism. In people with myopia (nearsightedness), the cornea is too curved, and items far away appear blurry. In those with hyperopia (farsightedness), the cornea is too flat, and items nearby and far away appear blurry. In people with astigmatism, the cornea is curved irregularly and items appear distorted. Spectacles and contact lenses are designed to compensate for visual imperfections – they bend the light before it enters the eye, helping the eye to focus.

What is presbyopia?

Presbyopia is a vision problem that is linked to the aging process. It usually begins in a person’s forties and causes items to appear blurry close-up. Presbyopia differs from refractive errors because it is unrelated to the shape of the eyeball. Instead, it is generally believed to it stem from a loss of flexibility in the lens of the eye.

Since presbyopia is not caused by a refractive error, it cannot be corrected by laser eye surgery. Likewise, laser eye surgery cannot prevent presbyopia.

Our St Helens practice offers various vision correction options for people with presbyopia. For more information, please contact Viewpoint Vision today.

What are the possible risks/side effects of LASIK eye surgery?

Although LASIK has proven to be very safe, it can occasionally cause certain side effects for our St Helens patients. Following LASIK eye surgery, some patients may experience dry eyes, flap complications, or visual disturbances (such as night vision problems, haze, halos, and glare). Occasionally, infections may occur following surgery or correction may be incomplete. Patients should understand that vision is not always perfect after surgery, though many patients do see marked improvements in their eyesight after receiving LASIK eye surgery at our St Helens centre. It is important to realize that LASIK eye surgery can’t prevent age-related vision deterioration. Finally, since LASIK eye surgery is a relatively new, there is no long-term data about the safety and effectiveness of this vision correction procedure.

Am I suitable for refractive surgery?

You may not be suitable for refractive surgery if:

  • You are in your early twenties or younger
  • You have health problems or a history of eye diseases/injuries
  • You are taking/have taken medications that affect wound healing
  • Your prescription has changed in the last year (refractive instability)
  • You are pregnant or breastfeeding
  • You have thin corneas, large pupils, or dry eyes
  • You have had previous refractive surgery

There are other factors that may make you a poor candidate for refractive surgery. Please speak to the surgeon at our St Helens practice to find out if refractive surgery is right for you.

Which is the best vision correction procedure for my eyes?

When deciding which vision correction procedure is right for you, we take many factors into consideration, including:

  • Your age
  • The nature and degree of the refractive error
  • Thickness of the cornea
  • Size of pupil
  • Thickness of the natural lens
  • Size and shape of the structures within the eye
  • Timescale of treatment effect
  • Patient inconvenience; e.g., post-operative pain, healing process, method of anesthesia, etc.
  • Time between treatment for first and second eye

Surgical experience, time scales, staging, predictability, stability, safety, adjustability, and reversibility are some of the considerations in choosing a vision correction application, whilst patient motivation, needs, and attitude/expectations govern choice as well.

No single technique is suitable for all types of refractive error. All forms of vision correction have their benefits and drawbacks. Refractive surgery involves many techniques, which are interdependent. It may not be possible to achieve a successful outcome through use of one technique in isolation.

It is important to remember that refractive surgery is a process, not merely a single operation. Therefore, treatment needs to be specific for each eye. After you come in for a consultation at our St Helens centre, we will be able to advise you on the vision correction technique(s) that is (are) most suitable for you.

Will refractive surgery allow me to “throw away” my glasses and contact lenses forever?

All refractive surgical procedures are designed to minimise your refractive error. That is to say that glasses of some description may still be necessary after vision correction surgery to provide the sharpest vision possible. However, reducing reliance on visual aids such as glasses and contact lenses is the object of the exercise. The greater the pre-operative refractive error, the more dramatic the surgical effect.

Refractive surgery is only contemplated on eyes and in patients with no other medical problems. If you are considering refractive surgery, you should bear in mind that any surgical procedure carries risks, which must be taken into account alongside potential benefits. No absolute guarantees can be given to any patient by any surgeon regarding outcome. Surgical treatment is carried out with the expectation of success by both patient and surgeon. Both parties must realise that surgery of any sort may require adjustment as well as possible management of minor or major complications.

What will my treatment cost?

This depends on the type of vision correction treatment you will be receiving. For current surgery prices, please ring the Viewpoint Clinic.

Will my treatment be covered by private medical insurance?

Normally, no. Refractive surgery is considered by most insurers to be cosmetic and thus is not normally covered. However, there are exceptions. We can discuss your payment options when you visit us for a consultation.

Can I afford refractive surgery?

Take the time to make the calculation and you will be surprised by the total cost of eyeglasses or contact lenses over a period of a few years. Our St Helens vision correction clinic may be able to help you explore financing options that will make refractive surgery affordable for you.

Why should I trust Viewpoint Vision with my eyes?

We have established a reputation as the pioneering centre for refractive surgery over many years. We have an enviable reputation and expertise in the practice of refractive surgery in the international arena, with numerous publications in peer reviewed journals and books on refractive surgery to our credit. Please read our page “why choose us”.

Vision and Refractive Errors

Normal Vision:

normal-vision

Normal Vision

The ability of an eye to focus near and far objects without the aid of corrective lenses is described as normal vision. Light is focused or refracted by the cornea, the clear window of the eye, and the lens inside the eye. Your vision is clear if the cornea and lens continue to focus near and far objects precisely on the retina. The retina is the inner layer of the eye that senses light and helps you to see.z

Young people, that are under the age of 40, have the ability to accommodate, that is to shift the focus from near to far objects automatically. Usually over the age of 40 (but with some individual variation) the ability of the eye to accommodate becomes compromised as the crystalline lens inside the eye becomes thicker and less elastic. This condition is known as Presbyopia, and means that reading spectacles are required. In normal vision, otherwise known as emmetropia, the image is focused sharply onto the fovea, the most sensitive part of the central retina that is able to discriminate fine detail.

Refractive Errors:

refractive-errors

Refractive Errors

If the image formed by the eye is not brought into sharp focus on the retina, but instead falls in front of it or behind it, this will result in a blurred image without glasses. This is caused by a mis-match, or refractive error, between the focusing ability of the cornea and lens on the one hand and the length of the eyeball on the other.

The main refracting surface of the eye is the cornea, which gives the eye approximately 44-45 dioptres of light bending or refracting power. It is in fact not the cornea itself but the tear film interface at which the rays of light are refracted. Within the eye the lens is the secondary focusing system and in a relaxed form contributes approximately 21 dioptres of focusing power. . This increases with accommodation so that near objects may be brought to focus on the retina. When this process fails with advancing years the condition is known as presbyopia.

Refractive errors are classified as MYOPIA, or short-sightedness; HYPEROPIA, or long-sightedness; and ASTIGMATISM. These disorders may be developmental and usually are so, or they can be acquired as a result of disease or injury. Normally focusing eyes (emmetropia) are approximately 23mm long from the front surface of the cornea to the retina. Their optical system (cornea and lens) focuses parallel rays of light (objects 6 metres away or more) onto the central retina.

Myopia:

In myopia, as a general rule, the eyeball is too long for the focusing system of the eye. Or, alternatively the focusing system at the front of the eye, principally the cornea, may bend rays of light too much causing the focused image to fall short of the retina.

Without their spectacles, short-sighted people can see near objects clearly, but usually objects beyond arms length are blurred or ‘out of focus’. Myopia is a very common defect affecting approximately one in five adults. It often commences in early teenage years and stabilises around 20 years of age. Myopic eyes may extend up to 30mm or 35mm in length. A near sighted or myopic eye has a far point of clear vision, which is very close to the eye depending on the degree of myopia. One dioptre of myopia (-1.00 D) would give an eye a far point of 1 metre, meaning that objects further away than that are blurred. Ten dioptres of myopia (-l0.00 D), would give a far point of just 10cm. Myopia or short-sightedness is sub-classified into two groups. In physiological myopia, the axial length of the eye as well as the cornea and the lens power are within normal limits for the population but are mis-matched so the image focus is in front of the fovea. Pathological myopia is a more serious form of myopia in which the degree of myopia is generally accepted to be more than 6 diopters with the eye having an axial length of more than 26.5mm. This is a congenital or neo-natal problem – that it to say, it stems from birth or shortly afterwards. The eyeball may be enlarged but its contents do not grow but stretch to fit the globe. This progressive problem may become apparent between the ages of 12 and 50.

If you wear myopic spectacles, then by holding them a few inches away from a printed page, you will note that they make everything smaller. Alternatively, if you have a spectacle prescription from your optometrist (Optician) your myopia will be indicated in the ‘sph’ box of the prescription with a minus (-) sign either above or in front of a number.

In high refractive errors, particularly high myopia, the edge thickness of high minus spectacle lenses is not only cosmetically unsatisfactory but the image quality is reduced by minification and optical aberrations. For example there is a ring scotoma (blank area) emanating from the periphery of the lens and the spectacle frame. Aberrations become more obvious the larger the spectacle frame. The visual freedom that beckons with refractive surgical procedures is very appealing to patients who are not only visually disadvantaged with their refractive correction but have very poor vision without it.

Hyperopia:

hyperopia

Hyperopia

Hyperopia, in contrast to myopia, is a condition wherein the image is focused behind the eye – in effect the eyeball is too short for the optical system either due to a small eyeball, that is usually 21 mm or less, or a cornea that is too flat, that is unable to bend the rays of light sufficiently to focus retina.

In hyperopia or farsightedness, contrary to popular belief, all images are blurred. Distance vision is blurred by a degree according to the degree of hyperopia but no part of the image is strictly clear and in particular near objects are difficult to bring into focus. The 1 dioptre hyperope (+1.00D ) would not be able to see at all clearly at a near point of 1 metre and a 10 dioptre hyperope would have a near point of 10 metres.

If you wear hyperopic spectacles, then your glasses will magnify if held a few inches away from a printed page. Your prescription will show a plus (+) sign in front of the ‘sph’ box.

Astigmatism:

astigmatism

Astigmatism

Astigmatism refers to a condition of the focusing system of the eye where the principle focus lies in more than one plane.

It is a physiological condition and may be of a small degree, which has little effect on the vision. The image formed within the eye may have two general points of focus between which the image is often reasonably sharp depending on the degree of astigmatism. Both images may fall short of the retina, one may be on the retina, one in front and one behind, giving rise to the terms such as compound hyperopic, compound myopic or mixed astigmatism. The usual cause of astigmatism is to be found in the cornea which is not spherical but is shaped more like the side of a barrel where it is steeper centrally and flatter at the edges. In the general population most eyes have astigmatism of a very small degree. Corneal astigmatism is due to a different radius of curvature in two meridians at right angles to each other (regular astigmatism) that causes an image to be focused on two different planes.

If you examine your prescription, you will note a second box usually marked ‘cyl’ and this represents any astigmatism you may have in your spectacle correction. The amount of astigmatism may be preceded by either a plus (+) or a minus (-) sign.

Presbyopia:

The human crystalline lens matures throughout life, doubling its weight over a 90-year life span. It also doubles in thickness, becomes increasingly yellow, and inevitably develops cataract at some point. The continuous generation of lens fibres causes increasing compression of the older fibres towards the centre of the lens. In the fifth decade of life the accumulated changes in lens anatomy reach a critical level in relation to near focusing as the lens gets less flexible. In other words, your arms become too short as you start to move reading material further away to see it more clearly! This loss of accommodation (the ability to change the shape of the crystalline lens) is known as presbyopia. Myopic eyes without their correction can of course bring close objects at some point although this might be very close. People often confuse presbyopia with short sight when in fact it is a variation of hyperopia i.e. for near vision only.

How Shortsighted or Longsighted am I?

Obtain your prescription (free from your optician if you don’t have a copy) and look at the numbers in the box labelled with ‘sph’. As we have noted above, if you are myopic then a minus (-) sign will appear above or in front of this box and if you are longsighted a (+) sign will be present.

It is generally said that minus one to minus three dioptres (-1.00 to -3.00) represents mild myopia, between minus three to minus six dioptres is moderate myopia and greater than six is considered high myopia. This also applies to hypermetropia or longsighted ness.

With regards to astigmatism (‘cyl’ box) low levels are considered to be up to 1.5 dioptres whereas high astigmatism is more than 1.6 dioptres.

Refractive Surgery

The goal of refractive surgery is to be able to correct any refractive error by surgical adjustment. Refractive surgery requires specialised knowledge from both a diagnostic and treatment point of view and is therefore clearly definable as a sub-speciality within ophthalmology. You should be advised by a surgeon who specialises in all forms of refractive surgery so that the best option in your individual case can be recommended.

From a surgical point of view the cornea is easily accessible for surgical processes to alter the shape. Altering the shape of the cornea will alter the focus of the eye. The other option is surgery to the lens. Modern micro-incision surgery of the eye and lens offers the opportunity to change the focusing power of the eye through implantation of a lens of appropriate power for the eye. It is an established, safe, predictable and fast method. You will find this method outlined in more detail in the chapter entitled ‘Lens Refractive Surgery:

Overview – Refractive Lens FAQ’s

Most people are aware that there are new developments in eye surgery intended to reduce the dependence on glasses or contact lenses. Refractive surgery includes several surgical and laser techniques designed to improve problems in focusing of the eyes. There are numerous options today for the permanent reduction of refractive errors. This commentary is not intended to be comprehensive but to give an outline view of what is possible together with some background information on ocular physiology and optics.

The goal of refractive surgery is to be able to correct any refractive error by surgical adjustment. Refractive surgery requires specialised knowledge from both a diagnostic and treatment point of view and is therefore clearly definable as a sub-speciality within ophthalmology. You should be advised by a surgeon who specialises in all forms of refractive surgery so that the best option in your individual case can be recommended.

From a surgical point of view the cornea is easily accessible for surgical processes to alter the shape. Altering the shape of the cornea will alter the focus of the eye. The other option is surgery to the lens. Modern micro-incision surgery of the eye and lens offers the opportunity to change the focusing power of the eye through implantation of a lens of appropriate power for the eye. It is an established, safe, predictable, and fast method. You will find this method outlined in more detail in the booklet entitled ‘Lens Refractive Surgery.’

Scope of Refractive Surgery

Refractive surgery today is capable of intervention in eyes from high myopia to high hyperopia. The range of say -37 dioptres of myopia to +16 dioptres of hyperopia can be treated. Treatment is also possible for astigmatism, from small degrees to gross degrees of astigmatism up to 12 dioptres and with eyeballs of short axial lengths less than 20mm to long eyes more than 26mm and up to extremes such as 35mm.

Surgical Options

Cornea (The cornea may be reshaped by:)

  1. Surface/stromal incisions – R.K. / A.K.
  2. Surface ablation – P.R.K. and LASEK
  3. Lamellar interventions – LASIK, Corneal Inlays and Intacs

Lens

  1. Cataract and Lens replacement surgery with accommodating Implants, multrifocal implants or Add On lenses
  2. Phakic Implants or a supplementary intraocular lens  (Visian ICL) for myopia and hyperopia and astigmatism

Combinations of the above

Sunglasses (8)

Sunglasses

Fashion aside, sunglasses serve an important purpose: protecting eyes from the harmful rays produced by the sun. You’re probably well aware of the need to protect your skin from the sun, but it’s equally important to protect your eyes.

About UV rays?

Ultraviolet (UV) radiation consists of invisible rays from the sun. The three bands of UV light are: UVA, UVB and UVC. UVC rays are of little concern as they are absorbed by the upper atmosphere and do not reach the earth’s surface.

UVB rays are the ones that burn the skin and can damage the eyes. Combined with cold wind and snow, UVB has the potential to cause snow blindness (photokeratitis), a temporary (lasting 12 to 48 hours) but painful problem in the cornea of the eye.

Although not all scientists agree, there is some research that suggests that daily exposure to UVB in very bright sunlight over a period of many years may cause cataracts, a gradual clouding of the lens of the eye.

Experts also suspect that the primary cause of eye growths such as pingueculae or pterygia is exposure to UVB rays.

People with cataracts (or who’ve had cataract or lens replacement surgery), macular degeneration, and retinal dystrophies should be extra careful.

Does colour matter in sunglasses?

Sunglass lens colors are really a personal preference -some change your perceptions of color, brightness and contrast, and some don’t. A neutral density gray will darken the world but not change your color perceptions. Certain lens colors can enhance your vision for certain sports; brown, for example, is popular with golfers because it provides nice contrast on those very green golf courses.

What is the most important feature to look for in a sunglasses?

The most important feature to look for in a sunglass lens is how much UV radiation it absorbs — you want 100% for maximum protection. Look for sunglasses that protect you from 99% to 100% of both UVA and UVB light. This includes those labeled as “UV 400,” which blocks all light rays with wavelengths up to 400 nanometers. (This covers all of UVA and UVB rays.)

Inferior sunglasses can be more damaging to your eyes than wearing no sunglasses at all. When one wears sunglasses the pupil widens; if the sunglasses have poor UV protection, then the eyes are damaged more by the sun’s rays.

It is also important to get lenses that are ground rather than punched, to minimize distortion. You may want to consider wraparound sunglasses to prevent harmful UV rays from entering around the frame. Polarized lenses are great for those who spend time on water, drive a lot, etc. The polarization actually cuts out the light coming from the horizontal meridian while allowing in the light coming in from the vertical meridian. In other words, it blocks the light that reflects in from water or the highway, reducing glare.

Is standing in the shade as good as wearing sunglasses?

Sunglasses reduce the UV more than if you were to stand in the shade, since the shade more or less evenly attenuates all wavelengths, visible and UV, while sunglasses preferentially attenuate shorter wavelengths (i.e., UV wavelengths).Thus, sunglasses provide more protection than shade alone.

Is it necessary to wear sunglasses in the winter?

While the sun’s rays feel less intense during wintertime, they are still strong enough to worry about eye damage, including the snow blindness mentioned above. New snow can reflect up to 80% of ultraviolet rays, according to the World Health Organization.

Should children wear sunglasses?

Children are at particular risk because they’re in the sun much more than adults, and their eyes are more sensitive as well. UV damage is cumulative over a person’s lifetime, which means you should begin protecting your child’s eyes as soon as possible.

Most parents would not allow their children to go outside without shoes, yet many seem unaware of the need to protect their children’s eyes.

When is sunlight most risky?

Most people think that they’re only at risk when they’re outside on a sunny day, but UV light can go right through clouds, so it doesn’t matter if the sky is overcast. The sun’s rays are strongest between 10 am and 2 pm.

Glare and reflections can give you trouble, so have your sunglasses ready if you’ll be around snow, water or sand, or if you’ll be driving (windshields are a big glare source).

The following put you at additional risk: sunlamps, tanning beds and parlors, photosensitizing drugs, and living at high altitudes or near the equator.

Vision and Refractive Errors (1)

Vision and Refractive Errors

Normal Vision:

normal-vision

Normal Vision

The ability of an eye to focus near and far objects without the aid of corrective lenses is described as normal vision. Light is focused or refracted by the cornea, the clear window of the eye, and the lens inside the eye. Your vision is clear if the cornea and lens continue to focus near and far objects precisely on the retina. The retina is the inner layer of the eye that senses light and helps you to see.z

Young people, that are under the age of 40, have the ability to accommodate, that is to shift the focus from near to far objects automatically. Usually over the age of 40 (but with some individual variation) the ability of the eye to accommodate becomes compromised as the crystalline lens inside the eye becomes thicker and less elastic. This condition is known as Presbyopia, and means that reading spectacles are required. In normal vision, otherwise known as emmetropia, the image is focused sharply onto the fovea, the most sensitive part of the central retina that is able to discriminate fine detail.

Refractive Errors:

refractive-errors

Refractive Errors

If the image formed by the eye is not brought into sharp focus on the retina, but instead falls in front of it or behind it, this will result in a blurred image without glasses. This is caused by a mis-match, or refractive error, between the focusing ability of the cornea and lens on the one hand and the length of the eyeball on the other.

The main refracting surface of the eye is the cornea, which gives the eye approximately 44-45 dioptres of light bending or refracting power. It is in fact not the cornea itself but the tear film interface at which the rays of light are refracted. Within the eye the lens is the secondary focusing system and in a relaxed form contributes approximately 21 dioptres of focusing power. . This increases with accommodation so that near objects may be brought to focus on the retina. When this process fails with advancing years the condition is known as presbyopia.

Refractive errors are classified as MYOPIA, or short-sightedness; HYPEROPIA, or long-sightedness; and ASTIGMATISM. These disorders may be developmental and usually are so, or they can be acquired as a result of disease or injury. Normally focusing eyes (emmetropia) are approximately 23mm long from the front surface of the cornea to the retina. Their optical system (cornea and lens) focuses parallel rays of light (objects 6 metres away or more) onto the central retina.

Myopia:

In myopia, as a general rule, the eyeball is too long for the focusing system of the eye. Or, alternatively the focusing system at the front of the eye, principally the cornea, may bend rays of light too much causing the focused image to fall short of the retina.

Without their spectacles, short-sighted people can see near objects clearly, but usually objects beyond arms length are blurred or ‘out of focus’. Myopia is a very common defect affecting approximately one in five adults. It often commences in early teenage years and stabilises around 20 years of age. Myopic eyes may extend up to 30mm or 35mm in length. A near sighted or myopic eye has a far point of clear vision, which is very close to the eye depending on the degree of myopia. One dioptre of myopia (-1.00 D) would give an eye a far point of 1 metre, meaning that objects further away than that are blurred. Ten dioptres of myopia (-l0.00 D), would give a far point of just 10cm. Myopia or short-sightedness is sub-classified into two groups. In physiological myopia, the axial length of the eye as well as the cornea and the lens power are within normal limits for the population but are mis-matched so the image focus is in front of the fovea. Pathological myopia is a more serious form of myopia in which the degree of myopia is generally accepted to be more than 6 diopters with the eye having an axial length of more than 26.5mm. This is a congenital or neo-natal problem – that it to say, it stems from birth or shortly afterwards. The eyeball may be enlarged but its contents do not grow but stretch to fit the globe. This progressive problem may become apparent between the ages of 12 and 50.

If you wear myopic spectacles, then by holding them a few inches away from a printed page, you will note that they make everything smaller. Alternatively, if you have a spectacle prescription from your optometrist (Optician) your myopia will be indicated in the ‘sph’ box of the prescription with a minus (-) sign either above or in front of a number.

In high refractive errors, particularly high myopia, the edge thickness of high minus spectacle lenses is not only cosmetically unsatisfactory but the image quality is reduced by minification and optical aberrations. For example there is a ring scotoma (blank area) emanating from the periphery of the lens and the spectacle frame. Aberrations become more obvious the larger the spectacle frame. The visual freedom that beckons with refractive surgical procedures is very appealing to patients who are not only visually disadvantaged with their refractive correction but have very poor vision without it.

Hyperopia:

hyperopia

Hyperopia

Hyperopia, in contrast to myopia, is a condition wherein the image is focused behind the eye – in effect the eyeball is too short for the optical system either due to a small eyeball, that is usually 21 mm or less, or a cornea that is too flat, that is unable to bend the rays of light sufficiently to focus retina.

In hyperopia or farsightedness, contrary to popular belief, all images are blurred. Distance vision is blurred by a degree according to the degree of hyperopia but no part of the image is strictly clear and in particular near objects are difficult to bring into focus. The 1 dioptre hyperope (+1.00D ) would not be able to see at all clearly at a near point of 1 metre and a 10 dioptre hyperope would have a near point of 10 metres.

If you wear hyperopic spectacles, then your glasses will magnify if held a few inches away from a printed page. Your prescription will show a plus (+) sign in front of the ‘sph’ box.

Astigmatism:

astigmatism

Astigmatism

Astigmatism refers to a condition of the focusing system of the eye where the principle focus lies in more than one plane.

It is a physiological condition and may be of a small degree, which has little effect on the vision. The image formed within the eye may have two general points of focus between which the image is often reasonably sharp depending on the degree of astigmatism. Both images may fall short of the retina, one may be on the retina, one in front and one behind, giving rise to the terms such as compound hyperopic, compound myopic or mixed astigmatism. The usual cause of astigmatism is to be found in the cornea which is not spherical but is shaped more like the side of a barrel where it is steeper centrally and flatter at the edges. In the general population most eyes have astigmatism of a very small degree. Corneal astigmatism is due to a different radius of curvature in two meridians at right angles to each other (regular astigmatism) that causes an image to be focused on two different planes.

If you examine your prescription, you will note a second box usually marked ‘cyl’ and this represents any astigmatism you may have in your spectacle correction. The amount of astigmatism may be preceded by either a plus (+) or a minus (-) sign.

Presbyopia:

The human crystalline lens matures throughout life, doubling its weight over a 90-year life span. It also doubles in thickness, becomes increasingly yellow, and inevitably develops cataract at some point. The continuous generation of lens fibres causes increasing compression of the older fibres towards the centre of the lens. In the fifth decade of life the accumulated changes in lens anatomy reach a critical level in relation to near focusing as the lens gets less flexible. In other words, your arms become too short as you start to move reading material further away to see it more clearly! This loss of accommodation (the ability to change the shape of the crystalline lens) is known as presbyopia. Myopic eyes without their correction can of course bring close objects at some point although this might be very close. People often confuse presbyopia with short sight when in fact it is a variation of hyperopia i.e. for near vision only.

I have worn reading glasses for years so I decided I would go for laser surgery. Read several negative reviews on high street stores and it appeared it was a case of do the procedure and that's it, no aftercare as such and not always good results. But then I came across Viewpoint. The reviews were good so I made an appointment. Although I initially thought I would be having laser surgery, Dr Chitkara recommended I had a Raindrop Implant. Although the thought of someone cutting my eye and inserting a lens, albeit tiny, terrified me I thought I would take the plunge and go for it! I can honestly say it was totally painless. Drops are administered in the eye and you cannot feel a thing. The procedure took about ten minutes and post-op Dr Chitkara suggested I take paracetamol if there was any discomfort - there wasn't. I have been for a check up every four weeks and everything is fine. I can now read without glasses unless it is very small, faint print. It can take six months to see the full benefit. I would definitely recommend Dr Chitkara and the Raindrop Implant, just wish I had had it done years ago! Beverley W –  Cheshire July 2016
Not the most pleasant surgery experience I’ve ever been subjected to but wow! What a great result! 34 years with spectacles and now 20-20 vision and given up smoking to boot! Well worth it!
Roy A  
My consultation was absolutely hospitable and enjoyable. I wish I knew this man before because I went elsewhere and did not receive adequate help even though I paid fees, causing me so much stress. The operation was easy, painless and all through the process DR Chitkara and staff were very friendly and reassuring. This has changed my life completely now my sight is restored. Dr Chitkara even phoned me after surgery at home to make sure I was doing well. I can’t say enough how I appreciate his service and kindness.
Amare G   
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