This information page has sections on Macular Degeneration and several related diseases. Click on the following links to find out more about the condition which is of interest to you.
Macular Degeneration occurs in 2 forms. These are "involutional" (DRY) which is age related and "neovascular" (WET). Both forms affect central vision causing loss of the ability to read and recognise faces.
People with macular degeneration usually retain enough peripheral vision to care for themselves and remain active, but reading a clock, a street sign, the destination particulars on a bus even telling the difference between a bus and a truck is difficult without central vision.
Reading, driving, sewing and any tasks that demand fine visual discrimination require a healthy macula. Without it, the world is visible but only in an imprecise way. However, macular degeneration seldom leads to total blindness.
Symptoms of Macular Degeneration
Macular Degeneration is characterised by loss, blurring or distortion of central vision caused by progressive deterioration of the macula, the small central area of the light-sensitive cells making up the eye's retina. A dark grey spot may appear in the central part of vision or the size of an object may appear different for each eye. It is the visual acuity which is most affected.
Diagnosis and Treatment
Although there are no symptoms in the early stages, an ophthalmologist can detect the condition during a medical eye examination before the symptoms appear.
Use of the "Amsler grid" at home can also lead to early detection
A person with macular degeneration can be helped.
Retina Australia NSW recommends that a person with a family history of macular degeneration or any of the above symptoms contact the Macular Degeneration Foundation for the latest treatments on 1800 111 709 or www.mdfoundation.com.au
Retina Australia NSW offers peer support on 1300 900 006.
Involutional macular degeneration is the technical name for what is often more simply described as "age-related" because it is commonly associated with aging. What happens with age-related macular degeneration is that the macula progressively thins and dries that is, it progressively atrophies as part of the aging process. Consequently, this condition is also labelled "dry" macular degeneration. This involutional or age-related form is by far the most prevalent form of macular degeneration, accounting for 90 percent of all cases.
Why the macular thins and dries in some older people and not in others is yet not known, although two things appear to be fairly clear. One is that some families seem to have a predisposition to age-related macular degeneration, meaning that family members are more prone to it. If someone in a family has macular degeneration, an ophthalmologist should examine annually all family members over 40. Additionally, there is now clear evidence that smoking can contribute to the development and progress of the condition.
At this stage there is no treatment for "DRY" AMD but diet can help delay the progression. For details of helpful diets contact the Macular Degeneration Foundation as mentioned above.
Neovascular macular degeneration is also labelled "wet" macular degeneration because it is fluid from leaking blood vessels in the retina that causes the light-sensitive cells of the macula to sicken and die. This can occur at any age but is still more common as age increases.
symptoms usually accompany this process. Straight-lines look wavy and
later blank spots may appear in your vision. If untreated much of the
nerve tissue in the macula may be killed or injured within a few weeks
or months. This damage cannot be repaired because nerve cells in the
macula do not grow back once they have been destroyed.
Retina Australia NSW recommends that you contact the Macular Degeneration Foundation for the latest forms of treatment on
1800 111 709.
There are several other diseases which are clearly genetic and in which the macula is damaged.
Stargardt Disease is the most common form of Inherited Macular Degeneration in patients under the age of 20. It is usually first noticeable between the ages of 8 and 12.
Diagnosis and cause
In this condition, the cone cells (at the macula) deteriorate in function and eventually die, while the rod cells generally remain intact. The diagnosis is usually made as a result of deterioration in visual acuity and typical appearances around the macula when the ophthalmologist looks into the eye. Electrical tests - such as the electro-retinogram (ERG), electro-oculogram and dark adaption testing - can measure the progress of the disease but are not usually necessary for its diagnosis.
Patients with previously normal vision develop irregularly shaped yellowish-white flecks or spots in the macula. This causes decreased central vision, reading and fine handwork may become difficult which eventually deteriorates to 6/60 as the flecks in the macula grow. In late stages of the disease, there may also be some impairment of colour vision.
In some, this deterioration is rapid, while in others it is much slower. There is no way to detect how fast this deterioration will occur in any individual. By the age of 50, about half will have a visual acuity of 6/60 or worse (defined as "legal blindness").
People with Stargardt disease do not usually have a problem with peripheral vision, and hence usually have little problem with bumping into objects when moving around. They may however experience difficulties in adjusting to light.
This is mainly inherited as autosomal recessive.
The gene for this disease has been located to the
shortarm of Chromosome 1. The gene has recently been identified as the
ABCR gene. The protein produced by this gene is involved in the energy
transport to and from the photoreceptor cells.
There is no cure, but research on this and other related diseases may identify a form of treatment
Fundus Flavimaculatus is a condition similar to Stargardt Disease but varies in its age of onset and severity. When there is macular damage, vision can deteriorate to 20/200, although it usually remains between 20/50 and 20/80. Damage to the macula first appears in the adolescent and early adult years, and the area of damage may gradually spread.
PERIPAPILLARY (pericentral) CHOROIDAL DYSTROPHY
Peripapillary (pericentral) Choroidal Dystrophy is a condition, which causes wasting of the blood vessels that surround the optic nerve. Patients first notice symptoms in the late adult years, when the macula is affected.
Stationary cone disorders are present at birth and have symptoms decreased acuity, decreased colour vision, sensitivity to light - that do not worsen with age. There are several types of stationary cone disorders (for example, cone monochromatism, blue cone monochromatism, dichromatism, trichromatism) with differing prognoses for visual acuity.
Pigment Pattern Dystrophy, which describes a group of disorders that includes Butterfly shaped Pigment Dystrophy of the fovea, North Carolina Macular Dystrophy, Macro reticular (Spider) Dystrophy and Sjogren Reticular Pigment Epithelium Dystrophy. The macular changes in these patients can occur at any age, but usually first appear in childhood. Many patients do not experience symptoms and may have visual acuities in the 6/6 to 6/24 range. Some of the genes have been identified for these disorders and are located on chromosome 6.
X-linked Cone-Rod Dystrophy is a rare disorder, and patients present with decreased central vision, may have a bull's eye lesion in the macula, a fine nystagmus, and no or very little pigmentary change in the fundus, until advanced stages of the disease. The visual field loss is slower than in x-linked RP, the ERG shows a cone-rod pattern if the ERG is recordable, which is often the case: unlike x-linked RP, in which the ERG is severely affected early in the disease.
BEST DISEASE/VITELLIFORM DYSTROPHY
Best disease (also known as vitelliform macular dystrophy) is an inherited form of macular degeneration characterised by a reduction of central vision.
Best disease affects the macula, the central part of the retina responsible for fine visual detail and colour perception. The retina and its component photoreceptor cells are essential to vision as they convert light into electrical impulses and then transfer these impulses to the brain via the optic nerve.
Although the age of onset of Best disease can vary, it is usually diagnosed during childhood or adolescence. In the initial stages, a bright yellow cyst (fluid-filled sac) forms in the retinal pigment epithelium (RPE) beneath the macula. On examination, the cyst looks like a sunny-side-up egg. Despite the presence of the cyst, visual acuity may remain normal or near normal (between 6/9 and 6/18) for many years. Peripheral (side, upper and lower) vision usually remains unaffected.
In many individuals with Best disease, the cyst eventually ruptures. Fluid and yellow deposits from the ruptured cyst spread throughout the macula. At this point the macula has a scrambled egg appearance. Once the cyst ruptures, the macula and the underlying RPE begin to atrophy causing further vision loss. As a result, central vision tends to deteriorate to about 6/36 late in life. However, Best disease does not always affect both eyes equally. Many individuals retain useful central vision in one eye with a visual acuity of about 6/12 in the less affected eye.
In some cases, Best disease does not progress far enough to cause significant central vision loss. However, retinal specialists can still detect the disease using sophicated diagnostic tests that measure the function of the RPE and the retina. Individuals with Best disease are also often farsighted which can be corrected with glasses.
Best disease is genetically passed through families by the autosomal dominant pattern of inheritance.
Currently, there is no treatment for Best disease. Ongoing scientific research is directed at understanding the cause of Best disease. A gene for Best disease has already been mapped (located to a specific region) to a human chromosome. Next, this gene will be identified and its function in the retina determined as the first step in developing means of treatment and prevention.
Individuals with Best disease may benefit from the use of low-vision aids and, possibly, orientation and mobility training.
Juvenile retinoschisis is an inherited disease diagnosed in childhood that causes progressive loss of central and peripheral vision (side, upper and lower) due to degeneration of the retina.
Juvenile retinoschisis (also known as X-linked retinoschisis) occurs almost exclusively in males. Although the condition begins at birth, symptoms do not typically become apparent until after the age of 10. About half of all patients diagnosed with juvenile retinoschisis first experience a decline in vision. Other early symptoms of the disease include an inability of both eyes to focus on an object (strabismus) and roving, involuntary eye movements (nystagmus).
The splitting of the retina into two layers causes vision loss associated with juvenile retinoschisis. This retinal splitting most notably affects the macula, the central portion of the retina responsible for fine visual detail and colour perception. On examination, the fovea (the centre of the macula) has spoke-like streaks. The spaces created by the separated layers are often filled with blisters and ruptured blood vessels that can leak blood into the vitreous body (the transparent, colourless mass of jelly-like material filling the centre of the eye). The presence of blood in the vitreous body causes further visual impairment. The vitreous body degenerates and may eventually separate from the retina. The entire retina may also separate from underlying tissue layers causing retinal detachments.
The extent and rate of vision loss vary greatly among individuals with juvenile retinoschisis. Central vision is almost always affected. Peripheral vision loss occurs in about half of all cases. Some affected individuals retain useful vision well into adulthood; with others experience a rapid decline during childhood.
Juvenile retinoschisis can resemble other retinal degenerative diseases such as retinitis pigmentosa (RP), Goldman-Favre viteoretinal dystrophy. Wagner's vitreoretinal dystrophy, and Stickler's syndrome. A thorough eye examination, including diagnostic tests measuring retinal function and visual field, combined with an accurate documentation of family history, can distinguish between these disease.
is genetically passed through families by the X-linked pattern of
At this time, there is no treatment for juvenile retinoschisis. However, in some cases, surgery can repair retinal detachments. Ongoing scientific research is directed at identifying the gene that causes juvenile retinoschisis as the first step in developing means of treatment and prevention.
Individuals with juvenile retinoschisis may benefit from the use of low-vision aids, including electronic, computer-based and optical aids, as well as orientation and mobility training.
Genetic Conditions Associated with Macular Degeneration
Inherited conditions include:
Which are caused by the accumulation of drusen, yellow-white deposits, in the macular area. Drusen deposits usually appear in the first three decades of life, and become larger as a person ages. Decreased vision may not be noticed until the fourth decade, with vision varying between 6/9 and 6/24. If the drusen causes other complications in the retina, vision may decrease to 6/60.
Which is a rare disorder in which new blood vessels grow under the fovea, resulting in fluid build-up in the macular, haemorrhage, and general wasting of other layers of tissue in the eye. Usually symptoms do not appear until after the age of 40. Drusen may also be present. People with this disorder may experience a rapid decrease in vision. The gene for this disorder has been identified as the TIMP3 gene, which is located on the long arm of Chromosome 22.
Which describes a group of disorders that includes Butterfly shaped Pigment Dystrophy of the fovea, North Carolina Macular Dystrophy, Macro reticular (Spider) Dystrophy and Sjogren Reticular Pigment Epithelium Dystrophy. The macular changes in these patients can occur at any age, but usually first appear in childhood. Many patients do not experience symptoms and may have visual acuities in the 6/6 to 6/24 range. Some of the genes have gene identified for these disorders and are located on chromosome 6.