Age-Related Maculopathy PDF

Age related maculopathy (ARM) is the leading cause of blindness in the western world and is likely to be the commonest eye disorder affecting the patients of a General Practitioner. Smoking, diet and ultraviolet light exposure appear to be modifiable risk factors. Included in this document Type...

Age related maculopathy (ARM) is the leading cause of blindness in the western world and is likely to be the commonest eye disorder affecting the patients of a General Practitioner. Smoking, diet and ultraviolet light exposure appear to be modifiable risk factors. Included in this document Types of ARM Symptoms Examination Management Treatment Key Points Types of ARM ARM occurs in two forms, the so-called ‘dry’ or non exudative type and the ‘wet’ or exudative variety. Dry ARM (Figs 1 & 2) is the most common and usually less severe of the two forms. Dry ARM is essentially a wearing out or degeneration of the retina. It is characterised by loss of retinal tissue, drusen (collections of retinal wastes) and pigment clumping. Typically the patient with dry ARM suffers slow progressive visual loss over many years. Wet ARM is a more devastating disease in which neovascular membranes form beneath the retina. These membranes elevate the macular area causing distortion, and like all new vessels in the eye have a tendency to bleed (Fig. 3). Subretinal haemorrhage causes sudden and profound visual loss and patients usually end up with an area of fibrosis beneath the central retina, which is known as a disciform scar (Fig. 4). Occasionally wet ARM responds to treatment with laser. Fig. 1. Dry ARM: Drusen. Drusen are Fig. 2. Dry ARM: Geographic atrophy Fig. 3. Wet ARM: Haemorrhagic Fig. 4. Wet ARM: Disciform (scar) accumulations of retinal debris. The and pigment clumping. As the retina phase. Sudden visual loss stage. Subretinal blood organises are usually associated with mild visual atrophies large areas of central accompanies such large sub retinal into a fibrous scar which distorts and loss. (Courtesy Assoc. Prof. R.S. retinal ‘melt away’ and retina bleeding. further damages the overlying retina. Clemett) pigment coalesces into clumps. Symptoms Patients with dry ARM usually notice a slow decrease in their vision; the visual loss is relatively symmetrical. Both distance and near vision are affected. Many patients are aware that their peripheral vision is normal and that they can improve their vision for some tasks by viewing eccentrically. Low contrast vision tasks such as reading newsprint become very difficult and in severe cases patients find it difficult to recognise faces and negotiate uneven terrain. Patients with wet ARM present with distortion and sudden visual loss. Distortion is a sinister symptom. Ask the patient whether straight lines such as the road markings or the edges of doors appear bent or wavy. Distortion indicates that there is elevation of the central retina due to either a neovascular membrane or subretinal haemorrhage. It is an ophthalmic emergency which requires urgent referral. Examination  Fig 5. The Amsler Grid. Patients view the grid with one eye at a time, concentrating on the central spot. They then report any distortion in the lines surrounding the central area. The test pattern falls only on the central macular area. The grids are available in tear-off pads, as illustrated. Vision Check the vision with and without a pinhole. Any improvement with a pinhole suggests that a change in spectacles will improve the vision. Check for distortion. The ideal tool is a device called the Amsler grid (Fig. 5) but you can simply show the patient a series of horizontal and vertical lines drawn on a piece of paper and ask whether the lines are distorted or wavy rather than merely blurred. Many patients with ARM are given an Amsler grid by their optometrist or ophthalmologist so that they can check for distortion on a weekly basis. Ophthalmoscopy Ophthalmoscopy is a very useful way of determining why an elderly patient can’t see. Elderly patients usually lose central vision from either cataract or ARM. If the red reflex is normal then it is most likely that the patient has ARM and would most benefit from referral to an optometrist in the first instance. However if the red reflex is attenuated by cataract, referral should be to an ophthalmologist unless there is also a clear improvement in the vision with a pinhole. The commonest findings seen with the ophthalmoscope are those in Figs 1 & 2. Patients can appear to have relatively severe disease and yet retain good vision and vice versa but in general those with marked macular changes will have poor vision. Management Referral Patients with spectacles more than two years old or whose vision improves with a pinhole should see their optometrist. Patients with cataract should see an ophthalmologist. Anyone with distortion or sudden visual loss should be seen urgently by an ophthalmologist. Occasionally laser can limit the visual loss caused by subretinal neovascularisation. Reassurance General practitioners play a vital role in helping patients come to terms with ARM. It is very important to reassure patients that that they will not go blind from ARM and that using their eyes will not hasten the progression of the disease. Even if the patient develops the most severe forms of ARM they will still have normal peripheral vision and should be able to care for themselves relatively independently. Advice Patients with ARM need to have the best possible spectacles and lighting. Recommend patients see their optometrist two yearly at least. In most main centres there are optometrists who specialise in helping patients with low vision and they usually stock and sell a variety of low vision aids such as magnifiers. Many low vision clinics have close relationships with occupational therapists who can be very helpful in liaising with the Blind Foundation and accessing other aid for patients. Patients with ARM often benefit greatly from magnification. To a certain extent magnification can be achieved with spectacles but this requires that objects are held quite close. A selection of simple hand magnifiers can be very helpful, left near the telephone book and at hand to check small print text. The best magnification is achieved by making objects larger or bringing them closer. Suggest a telephone with large numbers and remind patients that most libraries have a ‘big print’ section. Encourage patients to try simple things like enlarging crosswords on a photocopier and reassure them that sitting close to the TV is harmless. Lighting is also very important. Remind patients that light bulbs use very little electricity and that they should have the brightest bulbs that can be safely fitted in their room and angle-poise lights. Standard lamps and angle-poise lights are ideal devices that illuminate near tasks well. They should be placed so that the light comes from over the patient’s shoulder. When possible, natural light should also come from behind the patient, which may mean that chairs need to be repositioned in front of a well lit window. Televisions should be sited so that they are neither beside a window nor directly opposite or blinds pulled as necessary so that glare and reflection are minimised. Registration with RNZBF Many patients with ARM are quite resistant to registration with the Blind Foundation and require some gentle persuasion to avail themselves of its help. The Foundation provides a wide range of services from support and counselling to travel subsidies and access to large print and talking books. Patients with vision less than 6/18 are eligible for registration. Treatment There is increasing evidence that diet and pharmacological agents can alter the course of ARM. Diets rich in antioxidants and Omega III appear to slow progression of the disease. Megadose vitamin treatments such as Ocuvite PreserVision reduce the risk of sight threatening disease by 20% but are expensive. Ocuvite is contraindicated in smokers and patients taking warfarin. There is no evidence that low dose vitamin supplements help at all. All patients should be encouraged to  cease smoking and wear good quality sunglasses. Inexpensive, but good quality sunglasses are available from the Cancer Society. Key points ARM is likely to be the most common eye disorder affecting the patients of a General Practitioner. Most patients will retain vision sufficient for independent living but they do require reassurance, encouragement and practical suggestions. Visual distortion is a sinister sign which requires urgent referral. Smoking and a poor diet are the most common preventable causes. © GP Eyes - Dr Malcolm McKellar 2011