An ophthalmoscope is used to examine the retina and vitreous. Ophthalmoscopy aids visualization of the inside of the back of the eye including the retina, optic disc, choroid and blood vessels. It is often part of a routine eye examination. A direct ophthalmoscope is used for viewing the central retina. It is hand-held and powered with a light source. The instrument has to be adjusted constantly to focus on different structures within the eye. The light can be intense and disturbing. An indirect ophthalmoscope aids in examining the entire retina. This instrument is attached to the doctor's head and allows a clear view of the retina with a special lens. The patient may feel uncomfortable due to the intense light and pressure from the instrument.
Ophthalmoscopy is useful in detecting any changes in the retina due to diseases such as eye disease, diabetes, arteriosclerosis, high blood pressure or macular degeneration. Cataracts and other eye problems can be detected with an ophthalmoscope.
The patient's eyes are dilated so as to allow a good view of the insides of the eye. Some patients develop allergic reaction, vomiting, nausea and dizziness. This test is conducted in a darkened room where the patient is asked to look ahead at a distant spot. The eyes must be held steady without blinking. The ophthalmoscopy procedure may take just about 5 - 10 minutes.
Macular degeneration is the predominant cause of vision loss in the elderly. However, the word senile macular degeneration is often misinterpreted with respect to age-related macular degeneration (AMD or ARMD). The macula of the eye enables the central vision process. Macular degeneration occurs in dry and wet forms respectively. The dry form is the non-exudative form where as the wet form is the exudative form. In some instances, the advance of AMD is so slow that people may even fail to notice a little change in their vision. Whereas, in others the disease spreads faster and may lead to loss of vision in both the eyes.
Non-exudative Macular degeneration
The extra cellular deposits which are called drusen accumulate under the retinal pigment lead to the dry form. Although they appear pleomorphic, under ophthalmoscopy they generally tend to appear as discrete yellow lesions which are clustered in the macula referred to as pseudo papilledema. The symptoms of macular degeneration include difficulty in reading, recognizing faces etc. The peripheral vision remains but deteriorates gradually.
These lesions gradually become larger leading to multiple conditions such as retinal epithelial atrophy and also loss of photoreceptor function which causes vision loss. The enlargement of these lesions also results in retinal vein occlusion. Treatment with vitamins such as beta carotene, vitamin C and also zinc may slow down the process of dry macular degeneration.
Exudative Macular degeneration
The wet form or the exudative macular degeneration is a rare form of the disease. It occurs when the neovascular vessels arising from the choroid grow through defects in Bruch's membrane into the potential space of the retinal pigment epithelium. When these blood vessels leak, the retina is elevated along with the pigment epithelium leading to distorted or blurred form of vision. The symptoms resulting are generally gradual. However bleeding resulting from the sub retinal choroidal neovascular membranes may lead to acute vision loss. The exudative changes in the eye include hemorrhages, hard exudates, sub retinal / intraretinal fluid. Atrophy caused may be both incipient and geographic in nature. In addition to this, there is also a condition called central scotomas which is generally noticed as the missing areas of vision.
The neovascular membrane is difficult to locate by fundus examination since the locus of the membrane is beneath the retina. Angiography pertaining to the use of fluorescein or indocyanine may yield good diagnostic results. Laser ablation followed by the Angiography may prevent the onset of exudative macular degeneration.
Signs and symptoms of Macular degeneration
In gradual muscular degeneration, vision change is noticed slowly. The symptoms usually developed are:
Treatment of Macular degeneration
The wet from of macular degeneration is more likely to cause significant vision loss than the dry from and therefore different treatments for wet forms are available. These could help decrease the amount of vision lost. Laser treatment may stop or lesson vision loss in early stages of the disease. This is performed with specific wavelength designed to cauterize the abnormal blood vessels. A laser beam destroys blood vessels and may stop the growth of new ones. A scar forms after the treatment and this produces a permanent vision loss in that area of retina sacrificed to preserve the rest of the eye layer. Only a small number of people qualify for laser treatment and for many, vision may not improve after laser treatment. Photo dynamic therapy uses a light activated drug called verteportin given intravenously to the patient. A special laser is used to close the abnormal vessels while the retina is left intact. As closed blood vessels can reopen within a treated area, this may be necessary for one or two years. Exposure to light/sunlight should be avoided for five days after treatment. There are a number of drugs that block vascular endothelial growth factor and thus used as a treatment option. These have shown improvement in vision and not just delay or arrest the loss of vision due to macular degeneration.
Although macular degeneration is associated with age, genes related to the degeneration process of the macula have much significance. Factors such as obesity, hypertension, and oxidative stress may cause macular degeneration. Cardiovascular disease may increase the risk of macular degeneration. Among all the risk factors, smoking is considered as the most potent cause of macular degeneration. The risk of this disease in smokers is three times more than the other factors.
Optic neuritis is a condition where the optic nerve gets inflamed. Due to the inflammation, light and visual images are not clearly transmitted to the brain. Optic neuritis can be caused by autoimmune diseases such as multiple sclerosis or viral infections such as chicken pox or measles. Optic neuritis is usually the first sign of multiple sclerosis. This condition tends to affect more women than men.
Patients suffering from optic neuritis notice reduced vision. This is more so when the body temperature is elevated. The eyes are sore and painful when moved. There is reduced color perception and diminished peripheral vision. Persons suffering from optic neuritis may have headache and fever. The vision diminishes for about a week and then gradual improvement is noticed. Typically most patients suffering from optic neuritis tend to recover most of their vision within about 6 months.
The ophthalmologist will test the patient's color vision and visual field. Eye pressure and pupillary function will be examined. The optic disc is viewed with indirect ophthalmoscopy. Brain MRI may be taken for testing for multiple sclerosis. Intravenous steroid medication has shown results on those suffering from initial occurrence of optic neuritis.
Bibliography / Reference
Collection of Pages - Last revised Date: March 23, 2019