The macula is located at the center of the retina. The retina is tissue that lies at the back of the eye and is sensitive to light. The macula is the functional center of the retina giving individuals the ability to see "20/20”.
Also Known As
- Macula lutea
- Yellow spot
The macula measures about 5mm across in diameter. It contains large quantities of photoreceptor cells. Photoreceptor cells detect light and send signals to the brain. The brain then interprets them as images.
The fovea occupies the central part of the macula. It is a critical part of the eye, the one responsible for vision. The fovea contains specialized nerve cells called cones. Cones provide color vision. They also enable an individual to perceive things in fine detail.
The macula transmits the images that fall on the cornea and lens to the brain. The brain then converts those images into vision. The macula enables the sharp, detailed vision of objects close by such as written text and faces. It also functions to provide central and color vision.
Associated symptoms & disorders
Some of the conditions associated with the macula include:
- Diabetic retinopathy or diabetic macular edema affects the macula of patients with diabetes. It is the leading cause of vision loss in diabetic patients.
- Branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO) refer to the blockage of the main retinal vein. The blockage causes blood and fluids to spill into the retina causing the macula to swell. Central vision is affected and the condition leads to blurry or vision loss due to the death of nerve cells in the eye.
- When fluids build up below the retina, central serous chorioretinopathy results. Fluid can also build up under the retina when the retinal pigment epithelium (RPE) fails to work properly. The buildup of fluids can lead to vision distortion.
- Age-related macular degeneration (AMD) occurs when there is damage to the macula. When new blood cells grow abnormally below the retina, they give rise to wet AMD. Vision loss happens faster in wet AMD than in dry AMD. AMD leads to loss of central vision.
- The fluid that builds up in the macula causes swelling leading to macular edema. The swollen macula causes vision distortion.
- Macular hole occurs when there is a tear or opening in the macula. The tear forms a hole which affects the central vision. Things look blurry, wavy or distorted. Dark or blind spots also appear in the central vision. The condition is caused by age.
- Macular pucker is a condition in which bulges, creases and wrinkles appear on the macula. The disease is due to age with the retina pulling away from its normal position. It affects central vision.
- Macular telangiectasia (MacTel) affects the macula leading to loss of central vision. The disease develops as a result of problems with the blood vessels around the fovea.
- Stargardt disease is a type of macular degeneration caused by the break down of the macula. Photoreceptors die off resulting in blurry vision as well as loss of color vision.
- Other retina-related conditions that affect the retina and consequently the macula include choroidal neovascular membranes, cytomegalovirus retinitis, histoplasmosis, retinal tear and detachment, retinal pigmentosa, retinoblastoma, retinopathy of prematurity and Usher syndrome.
Diagnosis of associated disorders
The eye care professional will conduct tests to diagnose the different diseases. They include:
- Dilating the eye using eye drops to examine the back of the eye.
- In the case of retinitis pigmentosa, genetic testing, electroretinography and visual field testing are conducted.
- An Amsler grid to check for histoplasmosis. The test establishes whether there are dark, blurry or wavy areas in one’s vision.
- A cholesterol and blood sugar test for some conditions. A test to check for BRVO will establish whether there is a problem with blood clotting.
- Optical coherence tomography (OCT) which involves scanning the retina to provide very detailed pictures of its thickness. The test reveals any swelling of the macula.
- Fluorescein angiography in which the professional injects yellow dye into an individual’s vein. As the dye moves through the blood vessels, the professional takes pictures of the retina. The tests determine if there is any leakage.
Treatment of associated disorders
Scientists are yet to find the cure for some of the diseases like Stargardt disease and dry AMD. Patients with dry AMD may take vitamin therapy or nutritional supplements. Wearing sunglasses will help Stargardt patients protect themselves against ultraviolet rays. Vitamin A palmitate may help with retinitis pigmentosa. Others like central serous chorioretinopathy require no treatment and will resolve on their own.
Medical treatment choices include eye injections such as anti-VEGF medications. The injections reduce the swelling in the macula. They help with BRVO, CNVM, etc. Sometimes steroids can be injected into the eye to help with the swelling.
Laser surgical options include focal laser surgery, panretinal photocoagulation, thermal laser treatment, photodynamic therapy, cryotherapy and photocoagulation.
Vitrectomy is a surgical procedure where the vitreous gel and blood are removed from the eye.
Scleral buckle and pneumatic retinopexy help with retinal detachment.
Strengthening the immune system and taking antiviral drugs may help in some conditions. Observing proper diet and controlling blood sugar and blood pressure can also assist.
Cancer treating therapies are administered for retinoblastoma. They include chemotherapy, radiation, laser, cryotherapy, thermotherapy and enucleation (removal of the eyeball).
There is presently no cure for Usher syndrome and retinitis pigmentosa. Patients use low-vision devices and techniques to make the most of their vision.