Macular Vision
The macula is a vital part of the retina that is responsible for our central vision. It is involved in processing the light rays entering the central vision field. It is rich in cells called cones that convert light rays into impulses that travel through the optic nerve to the brain. Macular vision is about fine details, color and reading. Macular vision is intrinsic to our good vision. Problems in macular vision are usually due to drying out of certain areas of the macula or wet patches. Macular degeneration happens largely due to aging. Dry Macular degeneration or non-exudative macular degeneration is what is mostly noticed. It does not cause as much damage as wet macular degeneration. Symptoms of dry macular degeneration appear gradually and there is no treatment for this. Wet macular degeneration happens rather rapidly due to abnormal blood vessels in the retina. Photo dynamic therapy (laser) and anti-VEGF inhibitors are used to treat wet macular degeneration. Retinal photographs, visual acuity test, Amsler Grid and Fluorescein Angiography are tests that help determine macular vision problems.
Fluorescein angiography
Fluorescein angiography is a diagnostic test that aids visualization of the blood circulation in the retina and choroid. Fluorescein is a water-soluble dye that is injected into a vein in the patient's arm. It travels through the blood vessels of the body thereby aiding multiple photographing of the retina. The images obtained help in detecting any swelling or leakage in the blood vessels. The patient's eyes are dilated with mydriatic eye drops so that photographs of the inside of the eye can be taken.
Some patients may notice skin rash, itching or allergic reaction to the dye. Nausea or vomiting may be noticed. But this non-invasive test can usually be safely repeated. Abnormal results of fluorescein angiography test may indicate diabetic retinopathy, macular degeneration, or cancer. Ischaemia or oedema in the retina circulation can be detected with the help of fluorescein angiography
Opthalmoscope
An opthalmoscope 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 opthalmoscope 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.
Opthalmoscopy 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 opthalmoscope.
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 opthalmoscopy procedure may take just about 5 - 10 minutes.
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