General Ophthalmology Questions
FAQs about LASIK Surgery, Macular Degeneration, Contact Lenses and More at Our Laser Eye Practice in London
What is a refractive error?
Rays of light need to be focused sharply on the retina for us to see clearly. We can adjust our focus from near to far by changing the shape of the lens in the eye. The lens gets harder as we get older, making it more difficult to change our focus, which is why we usually need reading glasses later in life. The effect on vision of the lens getting harder is called 'presbyopia.'
The optical power of corrective lenses is measured in 'dioptres.'
Short-sight (myopia) occurs when the eye is longer than usual. Rays of light from distant objects are brought to a focus in front of the retina, making objects in the distance blurred. A 'minus power' lens is needed to move the focus back onto the retina. A spectacle prescription to correct three dioptres of short-sight would be written '-3·00'.
Correction of Short Sight
Long-sight (hyperopia) occurs when the eye is shorter than usual. Rays of light from the distance are brought to a focus behind the retina. Young people may be able to make distance objects clear by a focussing effort, but near objects in particular will become more blurred as age advances. Eventually, even distant objects will be blurred. A 'plus power' lens is used to bring the out of focus image forward onto the retina. A spectacle prescription to correct three dioptres of long-sight would be written '+3·00'.
Correction of Long Sight
Astigmatism (meaning 'without a point' of focus) usually occurs when the surface of the cornea has asymmetric curves, more like a rugby ball than a football. Part of the image will be focussed in one plane, and the other part will be focussed in another plane. For example, the eye might be effectively short-sighted for some rays of light, which will be focussed in front of the retina, but long-sighted for other rays that will be focussed behind the retina. A spectacle prescription to correct three dioptres of short-sight and one dioptre of astigmatism might be written '-3·00/-1·00 x 10°', where 10° is the angle of astigmatism.
The lens inside the eye has to change shape in order to focus on objects close to. As the eye ages, the lens becomes stiffer and the plane of closest focus moves away into the distance. This is called presbyopia. An additional plus power lens is needed to correct the problem. This additional prescription for reading glasses is recorded as an 'add'. So the spectacle prescription for an eye with long-sight and presbyopia might be recorded as +1·00, add +2·00. The 'add' might then be built into a bifocal or progressive multifocal lens thus:
Short-sight, long-sight and astigmatism can all be treated by laser. Presbyopia cannot be reversed by laser but the need for reading glasses can still be removed or reduced by carefully designing the laser treatment.
What is presbyopia?
Presbyopia is a vision problem that occurs due to aging. It typically begins in the forties and causes nearby items to appear blurry. Presbyopia is unrelated to the shape of the eyeball. Rather, it is believed to stem from a loss of flexibility in the lens of the eye. Because presbyopia is not caused by a refractive error, it cannot be prevented by laser eye surgery. Contact lenses and laser eye surgery can, however, help compensate for the loss of near focus.
What types of contact lenses do you offer at your London practice?
We offer almost every type of contact lenses at our London practice. Disposable contact lenses are soft contacts that can be thrown away either daily, weekly or monthly. For patients with astigmatism, we offer both hard and soft Toric contact lenses. Gas Permeable (GP) contact lenses can be harder to get used to than soft lenses, but often offer London patients a crisper, better quality of vision than other contacts. Bifocal Contact Lenses can improve both distance and near vision for people who also need reading glasses. For patients looking to alter the colour of their eyes, we offer coloured contact lenses. In addition we specialise in fitting complex lenses for medical indications.
What is radial keratotomy (RK)?
Radial keratotomy was an eye surgery method that involved making cuts into the surface of the eye to change its shape. RK was used for the treatment of short sight and astigmatism. Those who have had radial keratotomy can suffer difficulty with nighttime vision, and most have fluctuations in vision. RK was mostly abandoned around 1990, but is still available in one clinic in the London area. We have never recommended or performed RK treatment, which is now widely considered obsolete.
What are thermal techniques for treating vision problems?
Thermal techniques (radio frequency thermokeratoplasty, diode laser thermokeratoplasty, holmium-YAG thermokeratoplasty) have been used to treat low degrees of hyperopia and astigmatism in people over the age of 40. The effects depend on age. The maximum correction that can be expected in a 40 year old is about 1.5 dioptres, rising to about three dioptres for a seventy-five year old. The main disadvantages with all thermal techniques is that they are relatively inaccurate, the eyes can take a year or more to reach reasonable stability, and there may be a tendency for the effects to continue to wear off with time.
Laser Eye Surgery Questions
Am I suitable for refractive surgery?
You may be suitable for refractive surgery if:
- Your spectacle or contact lens prescription is stable
- You do not have any major health problems or a history of eye disease/injury
- You have a prescription that is within the recommended range for the procedure you are undergoing [for LASIK: up to around -12.00 (short sight) or +4.00 (long sight)]
You may not be suitable for refractive surgery if:
- You are taking or have taken medications that affect wound healing
- You are pregnant or breastfeeding or are within six months of pregnancy or breast feeding
- There are various other factors that may determine if you are suitable for laser eye surgery. Please visit our laser eye practice in Central London to find out if refractive surgery is right for you.
What are the possible risks and side effects of LASIK surgery?
Although LASIK has proven to be very safe, it can occasionally cause side effects such as visual disturbances (such as night vision problems, haze, haloes and glare) or temporary dry eye. As with any surgery, there is the possibility of surgical complications, or infections or inflammations. It is important for patients to be aware that LASIK surgery does not always result in "perfect" vision. Although there is now two decades of experience with laser eye surgery, data about its safety and effectiveness continues to be collected.
Will LASIK surgery completely eliminate my need for glasses or contact lenses?
After receiving LASIK surgery at our laser eye practice in London, patients usually find that they no longer need spectacles or contact lenses for most day to day distance vision purposes. However, they may still need to wear glasses or contact lenses for some purposes. Patients who undergo LASIK will also usually need to wear reading glasses when they reach their forties.
What is the difference between PRK, LASEK, and Epi-LASIK surgery?
The three refractive procedures differ only slightly - with PRK, Mr Bailey uses an excimer laser to reshape the surface of the cornea after removing the thin superficial skin of the eye. When performing LASEK or epi-LASIK surgery, however, the superficial skin is removed, set aside and is replaced at the end of the procedure. Either way, a new superficial skin regenerates in a few days.
What are "floaters"?
Most of the volume of the inside of the eye is filled with a jelly-like material called the 'vitreous' (meaning 'glassy'). The vitreous is tethered to a structure near the front of the eye called the 'ciliary body', to the retina along the line of the retinal blood vessels and to the optic nerve head at the back of the eye (figure 1).
Early on in life the vitreous is quite solid and rather immobile, but as the eye ages the vitreous develops splits in its structure that fill with fluid. This allows part of the vitreous to become more mobile. In most people, the vitreous eventually separates from its moorings to the optic nerve head and the retina allowing the back surface of the gel to float forwards. This event, called posterior vitreous detachment' (figure 2) can be precipitated by trauma, such as a blow to the head or to the eye, or can be a natural accompaniment of aging.
Floaters are particles embedded in the vitreous. Most are harmless remnants of a primitive blood vessel system that supplies the developing front of the eye during embryonic life. Whilst the vitreous is solidly in place the particles are immobile. They cast shadows on the retina but, because the shadows are always in the same place, the visual system adapts to their presence and they are rarely visible to their owner.
As the vitreous becomes more mobile the floaters start to move around more and their shadows move. This is when they become noticeable.
New floaters can arise and in the case of any sudden or rapid onset of floaters the person should seek the advice of an ophthalmologist (a doctor specialising in eye problems) without delay. If the vitreous detaches from the retina, the retina can be torn and bleed. A sudden shower of tiny black floaters may result. Inflammation in the eye can also produce an increase in floaters. When the vitreous detaches from the retina it can pull an arc or a ring of pigment from around the optic nerve head. This 'Weiss ring' floats forward almost directly into the line of sight. It is not dangerous at all but it can be particularly annoying. Sometimes people adapt to the presence of a Weiss ring over two or three months. Actually the term 'ring' is erroneous as less than a third of these floaters are complete rings!
The further forward the floaters are in the eye, the bigger the shadow they cast. A floater that looks small to the observer but that is near the front of the vitreous may seem very big to the subject, and vice versa.
How are floaters treated?
Treatment of floaters depends somewhat on their cause. Obviously, any underlying eye disease must be managed appropriately if present. For the floaters themselves there are three options:
1) Do nothing and put up with them;
2) YAG laser vitreolysis;
3) Surgical vitrectomy.
Laser treatment works best for fairly large, dense, central floaters. The large floater(s) are broken up into very small ones the annoyance value of which is usually much less. The Weiss ring floaters are often particularly good ones to treat by this method because of their size and their position in the field of vision, and thus their annoyance value, and because they are usually well clear of both the retina behind and the lens of the eye in front. Very diffuse, cloud-like, floaters and very tiny, fast moving, floaters are usually not suitable for laser treatment.
The success rate rather depends on the size, density and location of the floaters in the eyes, but if they can be lasered then there nearly always will be an improvement.
Is the surgical treatment of floaters safe?
The procedure is very safe, but not totally safe! There is an outside chance of incidentally damaging other structures in the eye due to the acoustic shock waves that are generated by the impact of the laser energy on the floaters. Both retinal detachment and cataract have rarely been reported. Retinal detachment is, of course, potentially sight threatening but can usually be repaired successfully. Cataract is eminently treatable although there is still a very small risk of sight-threatening complications in cataract surgery. Cataract following laser treatment occurs immediately.
If the floaters are unsuitable for laser treatment then the only other management option is surgical vitrectomy. This involves cutting the vitreous up inside the eye and sucking it out. It is very invasive and carries significant risk to sight, including infection inside the eye, which is potentially blinding, irreversible damage to the retina, and the inevitability of premature cataract that develops over months or a few years. It is rarely performed for floaters and only then if they are visually disabling.
BOTOX ® Cosmetic Injections
What are the possible side effects of BOTOX ® Cosmetic?
Many patients experience no side effects from BOTOX® Cosmetic. Bruising at the injection site occasionally occurs and can usually be covered by make-up. Temporary alteration of the position of the eye-brows or temporary drooping of the eyelids can occur with some treatments. Very rarely reported associations have included headache, respiratory infection, flu syndrome, nausea, pain in the face, redness at an injection site, and muscle weakness.
How long do the effects of BOTOX ® last?
The effects of BOTOX ® usually last about three to four months, but can sometimes last longer. Once patients receive BOTOX ® injections regularly, there is often a longer lasting effect.
Will I still be able to make facial expressions after receiving BOTOX ® Cosmetic injections?
Through BOTOX ® Cosmetic will improve the appearance of facial creases, it will not dramatically alter your appearance. After receiving the treatment, you will still be able to frown or look surprised - only without the wrinkles between your brows.
To make the most of your skin, in our consulting rooms in Harley Street, Jennie will advise you on the latest, the best and most effective cosmeceuticals and makeup on the market to make the most of your appearance; from vitamin C to repair your skin, Revitalash to stimulate lash growth to foundations that protect your skin, making you look radiant and healthy. Some makes we stock, others Jennie will advise you where to buy.
In the practice we have the well-known, tried and trusted Cellex-C range of vitamin C with their vitamin B complex containing hyaluronic acid; the Advanced Revitalash to stimulate eyelash growth; Susan Posnick's range of mineral make-up, no fillers or talc, just pure minerals, which has its own natural SPF of 26; Retinol A; Cellex-C sun protection SPF 32 and many others.
Jennie will advise you on the best products for you and at prices which are more economical that many high street brands.
Call Jennie on 07973 691727 or come in and see us in our consulting rooms in Harley Street, Central London, W1 where we've picked out the best for you.
Mr Bailey with questions about BOTOX ® Cosmetic, laser eye surgery, contact lenses, or the other types of vision correction offered at his ophthalmology and laser eye practice in London.