1. Getting rid of spectacle glasses or contact lenses. There is a slogan ‘Sight without glasses by laser’ coined by laser experts of modem times.
2. Retinopathy of diabetes that affects the retina of a diabetic person.
3. After cataract surgery.
4. Glaucoma.
5. Diseases of retina and vitreous.

Getting Rid of Spectacle Glasses by Laser

In recent times, as early as last decade, this subject has evolved to a path-breaking precision allover the world. So much so that experts now can predict 100 per cent results horn laser in getting rid of spectacle power in the following conditions where thick glasses are worn.

Myopia (Short-sightedness)

Short-sighted eyes have a minus power which may vary from as low as -0.5 to as high as -20.Laser is most commonly used for myopia between -2.5 D to 7.5 in ideal situation. The surgeon is the final authority. The average and common range is between -1.5 to -6. Less common range is -6 to -10 and least common is -10 to -20. But the common features of myopia are that they all progress with age and height (see chapter on Myopia) and one has to wear cumbersome and thick glasses.

(a) Cataract (lens sclerosis) (-15%).

(b) Lazy eye or squint correction with myopia of birth (amblyopia) (-10%).

(c) Detachment of retina (-12%).

(d) Vitreous hemorrhaged and floaters.

The incidence of these complications is not more than 20 per cent. Hence, the apprehensions of a mope person are based on flimsy grounds. About 80 per cent myopic carry on with their routine like anyone else.

Detachment of Retina and Vitreous Hemorrhage

These maladies find a solution with surgery under a very careful and planned regime in a retinal clinic. It is of utmost importance that surgery for retinal detachment in a high myopic be undertaken by a specialist of vitreous and retina. The modem treatments for retinal and vitreous problems are cryosurgery and laser therapy (photocoagulation) (see also the chapter on ‘Diseases of Retina and Vitreous’). Procedures on retina and vitreous are a super specialty under a surgeon trained for these only.

Squint and Lazy Eyes

Lazy eyes since birth and myopia with a squint need to be examined and treated in a special ‘orthoptic clinic’. Here the lazy eye is carefully assessed and attempts are made to restore vision by- exercises and visual stimulation (see also the chapter on ‘Squint or Cross-eye’).

Correction of Myopia by Laser/Lasik

The accepted therapy for myopia is by laser which is discussed in the next chapter. Besides myopia it can treat other refractive errors, e.g. astigmatism and hypermetropia.

1. When there is disparity of spectacle power correction between the two eyes, i.e. if the difference of power between the two eyes exceeds -3, ordinary spectacle glasses cannot work. If they are worn the wearer sees double (diplopic).

Contact lenses are the only way to deal with problem of diploid.

2. When cataract is removed from one eye and the other eye is quite normal (one-sided cataract removal).

3. Very high myopia with astigmatism of irregular kind (conical cornea).

It goes a step further in providing natural visual field and, above all, stops the myopia from increasing at an alarming rate. The last factor is singularly the most favorable point in contact lenses.

It is easy to understand that the placement of the lens on the surface of the cornea brings a film of tears between the lens and the cornea. This film of tear fluid, which has the same refractive index as the cornea, neutralizes any irregularity in the curvature of the cornea. The contact lens of a myopic has a minus number power ground into it from the spectacle power prescription given by the eye specialist. However, in practice, high-powered myopic with high astigmatism benefit additionally by the contact lenses.

There are two types of basic contact lenses-hard and soft contact lenses.

Hard Contact Lenses

A hard lens is made of highly inert and refined plastic material which rests on the cornea. It has no water and oxygen content and the nutrition to the cornea is supplied by the tear film and atmospheric air in and around the lens. These lenses cannot be worn for long stretches and certainly not during sleep. They rest lightly on the cornea due to surface tension. They move with lid movements. A clear area must be there between the cornea and the surrounding white sclera for free tear flow. There is a tendency for them to slip off if not properly fitted. This is perhaps their disadvantage. They correct even high astigmatism and are economical in cost. The hard contact lenses now do not find favors with eye specialists. They have been replaced by semi soft, comfortable and gas permeable lenses.

Soft and Semi-soft Contact Lenses

The soft lenses have a high water and oxygen content. They are very light, thin and collapsible, like a section of a balloon. They rest more comfortably and tightly on the cornea and the surrounding sclera and can be worn for a greater length of time. They do-not slip off or move with the lids. Their high water and oxygen content is a great advantage. They have a tendency to wear off if not carefully handled. They are delicate and require expert handling and sterilizations. Also they are more expensive. The semi-soft (gas permeable) contact lens have now replaced· the hard lenses for wearing in astigmatism. They are comfortable and have a long life.

(a) The wearer must have clean hands while inserting contact lenses. Nails must be short.

(b) The mirror should be used to wear and remove contact lenses. This prevents them from falling out and getting lost.

(c) A clean table with paper top is necessary if the contact lenses are being put on in a sitting position.

(d) The solution of care/washing must be regularly replaced on the expiry date.

(e) Enzyme tablets/boiling kit should be used under the supervision of a specialist in contact lens.

2. Polishing, sterilizing, inserting and removing contact lenses carefully and hygienically are very important to avoid source of infection.

3. The overstretching of lens wear-wearing contact lenses for more than the prescribed time accumulates mucus and infects the lens. The lenses, on an average, must be removed after eight hours of wearing and put away in cleaning lotion. A break of forty minutes or so before the next eight hours is ideal. Glasses can beworn during the break.

4. The wearing period of contact lenses, to be more practical, should be on the minimum side. Longwearing or extended-wear lenses are an exception and are recommended in a few cases only.

5. A word of caution is necessary about extended-wear contact lenses. They are ideal in conditions of pollution and dust, which are common in our environment. They require skilful fitting and careful follow-ups by the specialist.

acomplia medication small;”>6. The precise fitting and mounding of contact lenses over the cornea depend on the skill of the contact lens specialist. An excessively tight fit and loose fit on the cornea are both sources of irritation and strain. They can lead to infection in the long term. The fitting of a contact lens is a high-tech science and must be completely monitored and not left to the trader or ordinary technician. The wear and tear of contact lenses is detected by regular inspection and checking at a contact lens clinic or under the guidance of a contact lens specialist. A three-monthly check in a contact lens clinic is mandatory.

A torn, chipped or scratched lens is also a source of irritation and infection. The source of irritation and infection is not lens itself but the neglect and shortcoming in its maintenance by the user.

An expert has rightly said: Keep your contact lens as clean as you will keep your surgical instruments.

Subsequent, Bausch and Lomb Optical Co. of the USA purchased the Czechoslovakian patent and started manufacturing these lenses in the United States. Several new laboratories around the world have come out with various types of hydrophillis soft lenses.

The principal advantage of the soft lens is its initial comfort, mainly attributable to the softness of the material. The other contributing factors are the larger diameter of the lens and its very thin edges, so that when the lens is fitted, it gives the right limited movement on the eye. This fitting technique produces minimum contact between the lens and lid margins, thus reducing lid and eye sensation. The recent Bausch and Lomb soft lenses have dramatically improved the fitting of lenses by mounding the corneal curvature of average size.

Soft contact lenses are a godsend for patients with over-sensitive eyes who, in spite of all efforts of skilled practitioners, are uncomfortable with hard lenses. Such patients take to soft lenses from the first moment as there is no tearing or redness of the eye, and hardly any sensation of grit.

The period for adapting to the soft lenses passes extremely quickly in comparison with hard lenses. Patients comfortably wear these lenses through their working hours without any significant feeling of tiredness.

There are hard-lens-users who have fully adapted to their lenses to the extent that they are sometimes unaware of even the presence of the lenses in their eyes. However, they still have a noticeable narrowing of the visible fissure of the eyes, created by an unconscious effort on their part.

style=”font-family: Times New Roman; font-size: small;”>A hard-lens-user (whose lens has a smaller seeing area, Le. optic zone) may have to make a ‘squinting effort’ to help centre the lens geometrically to improve his/her vision. This effort may be conscious, but subconsciously the orbicular is muscles are continually tensed. This may also account for the complaint of some new hard-lens users that their eyes feel tired or they want to shut them near the end of their wearing schedule.

A comfort contributing factor with soft lens is its larger optic zone.

Fitting contact lenses is both an art and a science. And like the artist or the scientist, a contact lens practitioner cannot do his best work without all the tools of this trade at his disposal. In contact lens’ fitting this means, apart from being fully equipped with all the instrumentation, the practitioner must have access to all the various lens designs available, and be able to use them skillfully, judiciously and effectively as per the requirement of each individual patient in close coordination with the ophthalmologist.

Further, keratorfletry will denote rather steep corneal curvatures with or without a marked distortion of the mires depending upon the extent of progress of the cone.

The correction of vision via contact lenses is based on the principle of neutralization of the corneal irregularity by means of the fluid lens formed in the retro-Iens chamber. Contact lenses help to replace the irregular corneal surface. Hence, contact lenses are the treatment of choice despite several fitting difficulties, and the patient is usually satisfied. If contact lenses do not help a corneal graft surgery is the only choice.

In myopia, minus lenses are prescribed for its correction. This can be done by using spectacles, but the use of contact lenses has definite advantages, particularly in high errors. The advantages of contact lenses over spectacle lenses are as follows:

(a) Since contact lenses come in direct contact with the cornea, the cardinal points are least disturbed and, therefore, the extent of magnification of the retinal images as compared to spectacle correction is much less. In high myopia, spectacle correction will reduce the retinal image size to a considerable extent, thereby adversely affecting the visual acuity. However, with contact lenses the extent of magnification of retinal image size will be insignificant and will produce sharper images as compared to correctional spectacles.

(b) Contact lenses give a complete field of vision, more particularly in high numbers and the wearer is also free of prismatic effect, distortion and oblique aberration which he/she would face with conventional spectacles.

(c) It has been observed that patients in whom there is frequent change in refraction have stabilized after the regular use of contact lenses. It follows that contact lenses do have some arresting effect on the progress of myopia. It is also observed that patients who wear contact lenses need far fewer changes as compared to myopic spectacle-wearer. This may be attributed to the fact that contact lenses have restraining effect on the stretch of sclera and cornea.