How do I decide what refractive correction is appropriate for me?

A variety of refractive options are now available that will fulfill the needs of all patients. It would be best to discuss your needs and requirements with your ophthalmologist – after a detailed evaluation of your eyes, he would help you decide the most suitable option for your eyes.

What are the different types of spectacles and what are their advantages?

In general spectacles form a safe and effective form of correction for most visual needs. A variety of options exist for this – both in the form of frames which can be light and hardy – shell frames; rimless and semi-rimless for a more stylish appearance; metal frames in various colors and designs; and designer wear for the fashionable. Lenses for refractive correction can be single vision – and with the advent of the high refractive index lenses, these can be made quite thin, both in glass and plastic to allow an acceptable cosmetic appearance.

What are ‘progressive’ lenses and when are they indicated?

For older persons, who need bifocal corrections, the advent of the progressive lenses has proved a boon, and not only are these cosmetically better in appearance, they also provide enhanced functionality. The absence of a separately powered inferior segment – as in the traditional bifocal – allows a seamless change in power from that for distance vision, to that for near vision – and this also incorporates the effective correction for intermediate distance – which is especially useful for those who work with computers for their daily activities. These glasses are also more suitable for those who spend time outdoors and indoors as the lack of a bifocal segment enables them to adjust easily to all activities.

Where can I get these spectacles made?

Darshan eye clinic has an in-house optical service for the needs of its patients. Spectacle frames and a variety of lens choices are available to ensure that patients have their needs met in a scientific and cost effective manner.

When should I consider contact lenses?

If glasses are considered unacceptable for cosmetic or occupational or recreational needs, then contact lenses can help. A contact lens is a transparent lens which is positioned on the center of the black portion of the eye (the cornea). Contact lenses are basically of two types – soft and rigid. Soft lenses are usually preferred as they provide greater wearing comfort. For ‘simple’ myopic and hyperopic errors, without much astigmatism, regular soft lenses are adequate. These are now available as ‘disposable’ lenses – usually changed once in 2 weeks, once a month, or once in 3 or 6 months. The advantage of disposable lenses is that the protein buildup that occurs with long-term use, can be avoided. If however, the eye has a significant amount of astigmatism, then the regular soft lens designs will not provide clear vision. To correct this astigmatism, a special type of soft lens, called the toric lens must be used. In general, these lenses are more costly than the regular lenses, although these are also now available in disposable designs. If soft lens use results in an allergic condition in the eye, as happens rarely, then the patient may need to consider the use of rigid lenses, usually the semisoft design. These lenses are made of a different material compared to soft lenses, and can often be used when allergy develops to soft lenses. Another important indication for the use of these semisoft lenses is when the cornea is abnormal. This may be due to the presence of corneal scarring from previous injury or infection, or due to a loss of the regular shape seen in some genetic conditions – the commonest of which is keratoconus. In other eyes that have been fitted previously with very tight soft lenses, the corneal periphery called the limbus and the delicate cells on the back of the cornea – called the endothelium, may suffer from the lack of a proper oxygen supply and in these eyes, the use of a semisoft lens (also called a rigid gas permeable lens or RGP lens) is a better design, as it promotes a better oxygen supply to the cornea and limits further corneal damage.

What does the contact lens fitting process involve?

The optometrist will measure the corneal curvature in your eyes using an instrument called a keratometer. Using these values as a guide, an appropriate ‘trail lens’ from a set available in the clinic is fitted to your eye. The fit of the lens on the eye is assessed, and if required modified. Vision is tested and the correct power required for the lens is determined. In the case of regular soft contact lenses – they can be directly made available from the inventory available at Darshan Eye Clinic. For toric soft contact lenses and for the RGP lens, the appropriate lens is ordered from the laboratory and delivered to the patient in 24 to 72 hours. The Contact Lens Clinic will also provide the patient with detailed instructions on the use and care of the lens and the necessary solutions that are needed to maintain the contact lens. In order to help fit patients with distorted corneas, the clinic has a special set of contact lenses that have allowed patients with difficult problems – due to shape distortion or after corneal surgery, to be fitted with comfortable lenses that allow clear vision.

Are there other types of ‘special’ contact lenses?

Yes. Apart from the lenses described above which are for providing the patient with good vision, there are other types of lenses as well.

TIPS FOR CHOOSING THE RIGHT SPECTACLES

Although nature ensures that most people see well, in some eyes a mismatch between the “power” and “length” of the eyeball, results in poor vision – this is termed a refractive error. These can be classified as myopia, hyperopia, or astigmatism – depending on whether the power is too high, too low, or different in different axes. Presbyopia is the term used to describe the need for reading glasses. Traditionally, refractive errors have been treated with spectacles, and while these work well in the majority of patients, some simple rules have to be followed when selecting them. These include –

1.Choose the right frame – Since spectacles are usually worn throughout the day, having a comfortable frame is very important. A good fit is as important as a trendy look. The most important aspect of a frame is that the eyes should see through the center of the lens. Hence, please wear he frame and look at yourself in the mirror to ensure this. Since the shape of each face is different, this can sometimes be a challenge. Once this is done, make sure that the length of the side stem is appropriate – the loop of the stem should fit securely around your ear – if it is too long, the frame will tend to slide forwards when the head is tilted. However, if too short or too tight, the pressure exerted by the frame will result in a headache. A shell frame distributes the weight of the spectacles on the bridge of the nose and is less likely to leave unsightly pressure marks on the nose, unlike frames with nose pads. Rimless frames look nice, but are quite delicate and should be chosen only if proper care will be exercised, as they tend to get bent and distorted quite easily.

2.Pictures – Face with correct frame centration and poor centration; Side view of face with correct stem length, too long, and too short; Shell frame and frame with nose pads; Rimless frame.

3.Choose the correct lens – The optician will ensure that the power and centration of the lens are appropriate. However, there are other choices that you can make when choosing your spectacles and it is important to be aware of them. In general, glass lenses are heavier than plastic lenses and this is especially true for higher refractive errors. Plastic lenses are also the best choice when choosing spectacles for children, as they do not break and are hence safer. Similarly, when choosing a delicate frame, be sure to use a plastic lens to lessen the weight of the spectacles. To reduce the thickness of the lens – in higher refractive errors, choose a high index material – both in glass and plastic. Choosing a frame with a smaller eye segment will also help in achieving a better cosmetic appearance in such cases. Tints in the lens help reduce glare, and do not interfere with vision in indoor lighting conditions. For those who spend a lot of time outdoors, a photochromatic lens, which darkens on exposure to sunlight, can be helpful. Antireflective coatings help to reduce glare at night. Scratch resistant coatings will reduce the risk of damage to the lens surface.

4.Pictures – High power with standard and high refractive index lens; With small frame; Tint; Photochromatic with change.

5.Reading glasses – For those who do prolonged reading, a separate pair of glasses in a regular frame, will provide greater reading comfort. However, for those who are mostly outdoors, with only occasional reading requirements, using half segment readers are more convenient as they can carry these small frames more easily. For those whose work requires the constant use of both distance and near vision, as in an office environment, the use of bifocals is recommended. These lenses consist of two distinct segments – an upper portion for distance viewing and a lower portion for near viewing. If the person has predominantly distance viewing requirements, a kryptok bifocal, with a smaller reading segment is helpful; while for those with more reading requirements, an executive bifocal, with a larger reading segment is helpful. The presence of two distinct segments with a dividing line can be disturbing in some individuals, due to the image jump when the eye traverses this line. In these individuals, and also in those who use computers a lot, the use of a progressive or transition lens – in which there is no distinct separation of the distance and near segments of the lens, is helpful.

6.Pictures – Regular frame and half segment readers; Kryptok and Executive bifocals; Progressive lens.

Looking after your spectacles is as important as making the right choice when ordering them. Carry the spectacles in the provided box to ensure that they do not get damaged. Clean the lens with soap and running water, and then shake them dry, before gently cleaning the surface of the lens with the provided cloth. Do not clean them when there is dust and grime on the surface – as this can result in scratches. Be sure to regularly clean the hinges of the frame to ensure that they open and close smoothly. We hope the above information has been helpful in making your use of spectacles a safe, comfortable, and rewarding experience. If you have any suggestions or comments, please do let us know at darshaneye@gmail.com.

Please note that refractive errors can also be treated by contact lenses and by excimer laser corneal surgery (PRK and LASIK), if you desire not to wear spectacles. To check if these options are suitable and advisable for you, please consult your ophthalmologist, who will help you decide.

CONTACT LENSES – YOUR CHOICES

Although nature ensures that most people see well, in some eyes a mismatch between the “power” and “length” of the eyeball, results in poor vision – this is termed a refractive error. These can be classified as myopia, hyperopia, or astigmatism – depending on whether the power is too high, too low, or different in different axes. Presbyopia is the term used to describe the need for reading glasses. Traditionally, refractive errors have been treated with spectacles, and while these work well in the majority of patients, some patients find these inconvenient. These are usually due to work environments, sporting, or cosmetic requirements. To help such people see well, without using glasses, contact lenses are often used. Apart from the fact that these devices allow clear vision without glasses, they also provide better quality of vision and larger field of view in those with high refractive errors. In some patients, your doctor may suggest the use of these devices for medical reasons – these include patients with irregular corneas, in whom clear vision cannot be achieved by the use of glasses; and those in whom corneal problems result in significant pain, in whom these lenses are used to provide comfort and promote corneal healing. Lastly, contact lenses can also be used to change the color and appearance of the eye, for cosmetic reasons.

Types of Contact Lenses – Contact lenses are available in two basic material designs – soft lenses, which as the name implies, have no shape of their own; and rigid gas-permeable lenses, which can maintain their shape. Hard lenses are seldom used today, as they tend to cause too much corneal damage over time.

Soft lenses – Soft lenses are large lenses (diameter more than that of the cornea), and are very stable when worn on the eye. These are usually very comfortable, and are ideal for those interested in pursuing sporting activities. They come in a wide range of powers, and for those with low astigmatism, can be obtained on the same day. With daily use, these lenses tend to accumulate debris from the tears and ocular surface, and this can sometimes result in an increased risk of allergies, and more rarely – infections. To overcome this, manufacturers now offer “disposable” lens packs – which can be biweekly, monthly, 3 monthly or 6 monthly packs. The lenses in the monthly packs for instance, are used daily, and once the month of use is completed, they are discarded and fresh lenses are used. This reduces the risk of allergies and infections with long-term use. One of the main disadvantages of regular soft lenses is that they do not have an inherent shape of their own, and thus, tend to assume the shape of the cornea. They thus, cannot correct astigmatism – a condition in which the cornea has a different curvature in the two meridians. To overcome this problem, one can use a special variety of soft lens – termed the toric lens, in which the design allows correction of the astigmatic error as well. These usually have to be ordered specifically for each patient, depending on the axis and power of the astigmatism. For those who also need glasses for reading, bifocal lenses are now available, which allow the patient to see well for both distance and near, without glasses.

Rigid lenses – Since these lenses can maintain their shape, they are ideal for treating astigmatism, and other corneal irregularities. They are smaller in diameter than the underlying cornea, and hence tend to move more than soft lenses. They are thus, not very suitable for those who like to use lenses when playing sports. However, the greater movement allows for more tear exchange under the lens, resulting in better delivery of oxygen to the cornea. Since they are made of a different material compared to soft lenses, they can be used in patients who have developed an allergy to the soft lens.

WHAT’S NEW ?

ROSE K LENSES – While the two lens systems described above, can correct the majority of patients with standard refractive errors, they are inadequate in those with special corneas – these include those with a corneal problem called keratoconus, those who have undergone corneal transplant surgery, LASIK or other refractive surgery, and in those who have corneal scarring or irregularities resulting from injury or infection. In these patients, special lens designs which have computer aided posterior lens curves, or a reverse geometry design – are required to provide the patient with wearing comfort and clear vision. The Rose K lens set helps us provide such patients with clear vision in even the most difficult corneal conditions, by individually customizing the contact lens for each patient’s requirements.

Looking after your contact lenses is as important as making the right choice when ordering them. Carry them in the provided cases to ensure that they do not get damaged. Clean the lens according to the instructions given to you and ensure that you thoroughly wash your hands with soap and water before you handle the lenses. Be sure to regularly clean the lens case, following the instructions given to you. We hope the above information has been helpful in making your use of contact lenses a safe, comfortable, and rewarding experience. If you have any suggestions or comments, please do let us know at darshaneye@gmail.com.

Please note that refractive errors can also be treated by spectacles and by excimer laser corneal surgery (PRK and LASIK), if you desire not to wear contact lenses. To check if these options are suitable and advisable for you, please consult your ophthalmologist, who will help you decide.