At one time almost all intraocular surgery was performed under a local anaesthetic. For two reasons local anaesthesia is used much less commonly today. First, the whole science of general anaesthesia has greatly advanced and the likelihood of coughing has been considerably reduced. Second, methods of repairing the cataract wound are now better than they used to be. Coughing and sneezing after the operation consequently constitute less of a threat than formerly. Read the rest of this entry »
There is a popular misconception that cataract surgery cannot be undertaken until the cataract has reached a particular ripeness. This was the case many years ago, when the only method of removing the cataract was by the extracapsular method, which involved opening the capsular bag and washing away its contents. If the cataract was very ‘immature’, it was technically rather difficult to do this. Read the rest of this entry »
When examining you an ophthalmologist will test eye-pressure through the simple expedient of placing his fingers on your closed eyelids. The experienced physician will know immediately whether the pressure is unusually high, but even so he is unlikely to be able to distinguish, using this technique, between more than four grades: namely soft, normal, suspicious and high. Accurate measurement requires instruments. Such instruments have to touch the cornea, which is therefore suitably anaesthetized beforehand, using a special kind of drop. Several types of local anaesthetic drop exist, e.g. amethocaine, pentocaine and xylocaine. One instrument blows a puff of air on to the cornea and then measures the degree of corneal flattening that results. This does not require a local anaesthetic. Read the rest of this entry »
Until the advent of contact lenses or intraocular lens implants spectacles were the only means of achieving a finely focused image on the retina after a cataract operation. Although in many cases this is most satisfactory, there are limitations to such correction. At first some patients find that wearing thick cataract glasses causes a number of problems which arise from magnification of the image, distortion in the peripheral part of vision, and some limitation of the field of clear vision.
These all result from the spectacle lens itself rather than from the operation. Read the rest of this entry »
For the first two weeks or so of the immediate postoperative period vigorous activity is discouraged. Stooping, lifting heavy objects, sneezing or coughing, and any very violent physical effort should be avoided. Any activity that makes the patient feel that his collar is too tight or that his neck is swelling should be stopped because movements which cause congestion in the head also provoke an increase in pressure within the eye. Until the wound is properly healed this could lead to its leaking, to haemorrhage, to poor healing, and, in the worst event, to loss of the eye. After two weeks, however, the surgical wound should be well healed. At the routine outpatient visit which should be made at this time, the state of healing will be assessed by the surgeon, who will tell the patient what physical activities may be undertaken. Read the rest of this entry »
These then are the common errors of vision which may cause eye-strain. They are short- and long-sightedness, near-vision deficiency and astigmatism. Most commonly astigmatism is present with one of the other three conditions. They may all be measured by both objective and subjective methods. Objective measurement means the use of instruments, while subjective measurement requires you to state an opinion. In ordinary practice the practitioner will use both methods, and thereby establish a pattern which enables him to prescribe the right optical correction. If you repeatedly give a wrong answer to a subjective inquiry the experienced occulist will proceed to further objective (optometrical) tests. Read the rest of this entry »
Strabismic disorders in the adult may also be associated with certain diseases and drugs affecting the nervous system. In the child, however, the chief causes are congenital. Treatment of squint can be generalized as follows. The first step must always be to establish why the eyes are not working together, and this necessitates a full ophthalmic examination. Special (orthoptic) tests to measure the degree of weakness in the affected eye and to clarify whether the defect is sensory or motor, using electronic equipment, may be required, especially if the patient is a child. Read the rest of this entry »
As regards lens-implant surgery the benefits are very great. To be able to have normal sight again without the need for thick spectacles or the bother of wearing contact lenses is surely the preferred treatment. Where contact lenses are used subsequent to a cataract operation, they differ from ordinary contact lenses in certain ways. The condition of an eye that has had its crystalline lens removed is known as aphakia, and aphakia almost invariably demands a contact lens that is much thicker in its centre than the lens worn by the ordinary short-sighted person. Read the rest of this entry »
A plastic lens placed in the eye where the original crystalline lens used to be seems the ideal method of correcting the vision of a patient who has undergone cataract removal. Normally the crystalline lens has an optic power of nearly 20 dioptres, equal to a strong magnifying glass, and obviously an eye of normal size requires this power to be replaced. An implanted artificial lens is one way to achieve the necessary correction. It is wrong, however, to suppose that once the operation has been performed the patient will be able to see clearly immediately. This can only occur if the implant has been expertly placed in the eye, and if the right adjustments to the optic power, using spectacles, have been made. It is sometimes necessary to perform a second, less difficult operation after a few weeks have gone by. Read the rest of this entry »
As we get older, all our blood vessels acquire harder walls, making it more difficult for the heart to pump blood through the whole system, especially the smaller vessels. Resistance to the flow of blood results in increased, or ‘higher’, blood pressure. The heart simply has to work harder in order to meet and overcome the developing resistance. The small vessels of the retina, or arterioles, can be examined minutely with an ophthalmoscope and changes of hardness in their walls easily seen. Because they are so small and fine they are sometimes the first to break down, so that if the blood pressure becomes very high they may leak blood and serum. When this happens the results can easily be seen on the surface of the retina between the vessels. Read the rest of this entry »
