Eye Dictionary: M
M
Macugen. An anti-VEGF injection medicine used in the treatment of wet macular degeneration. This medicine is being supplanted by other drugs in the same class such as Avastin (cheaper) and Lucentis/Eylea (possibly more effective).
macula. The macula is the part of the retina that is responsible for our fine central vision. This is the vision necessary for reading a book, watching television, or seeing distant road signs. The retina works like film in a camera, and the macula is the most sensitive part of the film, containing more rod and cone photoreceptors than elsewhere. Problems at the macula, such as diabetic retinopathy or macular degeneration, can cause severe visual changes (though the peripheral vision remains intact). The macula can be viewed through dilation. The macula can also be measured using OCT photographs to look for swelling or sub-retinal bleeding. When there are problems, such as wet macular degeneration, the circulation under and around the macula can be further imaged using fluorescein angiogram (though this type of testing is usually left to retinal specialists).
macular degeneration. Macular degeneration is premature aging of the retina. The retina is located in the back of the eye and works like "the film in a camera," detecting light and images. The macula is the central retina responsible for fine central vision. If the macular retina wears down this can cause serious problems. For most people, this results in difficulty seeing fine details such as small type in books ... though ARMD can cause serious vision loss when advanced. Most people have dry macular degeneration where the vision slowly worsens with time. Treatment for dry degeneration is limited, and revolves around using eye vitamins and vision screening with an Amsler grid at home and OCT scans at our office. Some people go on to develop wet macular degeneration where the retinal blood vessels leak fluid and this can lead to rapid vision loss. Wet degeneration causes significant vision changes, but there are also more treatment options such as anti-VEGF injections and laser. Wet degeneration can be detected with OCT scans and leaky areas further localized using fluorescein angiography.
macular edema. This is swelling of the macula, the area of the retina that is responsible for our fine central vision. The retina can be thought of like film in a camera. Just like film, the retina needs to be perfectly smooth and flat if we are going to "take a good picture" and see clearly. If there is swelling at the macula, then the "film" becomes distorted in the middle and this creates blur or distortion to the central vision as well. There are many causes of macular edema, such as leaking
vessels from wet macular degeneration, diabetic retinopathy, or traction from epiretinal membranes. Retinal edema can be detected in our office using OCT photographs to map out the retinal surface. Early retinal changes may even be detected at home using an Amsler grid. Treatment for this condition depends upon the cause, but usually involves injections of anti-inflammatory medications (such as Kenalog or Avastin) if there is active bleeding or if the edema is not resolving.
macular hole. This is a small hole that forms in the macula that creates significant vision problems. The retina is located in the back of the eye and acts like film in a camera. The macula is the most important part of the retina as it is responsible for our fine central vision. If a hole forms in this area, the central vision "goes to pot." There are several causes for a macular hole. One is an epiretinal membrane. This is a clear fibrous membrane that can form on the surface of the retina with age (and sometimes after trauma). This membrane can contract like "shrinkwrap plastic" and cause traction on the retinal surface. This creates wrinkles on the surface of the retina and if bad enough, can pull open a full-thickness hole in the macula. A hole can also form from the traction of a vitreous detachment. The vitreous is the gel that fills the rear chamber of the eye. The vitreous has a tendency to contract and collapse inwards with age, tugging on the retina. This can create retinal tears or holes and lead to a retinal detachment. If this tugging occurs at the macula, a full thickness hole can result. Macular holes, if small enough, may close on their own but often require surgical correction. This usually involves a membrane peel surgery. In this surgery, a retina specialist will enter through the back of the eye and remove the source of the traction (i.e., remove the epiretinal membrane or vitreous jelly). Then, a gas bubble is injected into the eye in order to smooth out the retina, and (hopefully) the hole will close over the next several weeks. Though a commonly performed surgery, membrane peels are not always successful. A macular hole causes central vision distortion that can be detected with an OCT scan of the retina. Amsler grid monitoring at home may pick up an early macular hole as well, but definitive diagnosis is made in the doctor's office.
macular pucker. This is a membrane that forms on the surface of the retina that causes it to wrinkle or "pucker." Other names for this are epiretinal membrane and cellophane retinopathy. See the entry on epiretinal membrane for a more detailed explanation of this common finding.
Malyugin ring. This is a small spring-like device used during cataract surgery to help dilate the pupil. Small pupils make cataract surgery difficult, as the procedure involves vacuuming out the cataract "through" the pupil. Some people have naturally small pupils (the black hole in the middle of the iris) and don't dilate well. Poor dilation may be genetic or occur from atrophy of the iris muscle that occurs with age. The smaller the pupil, the more difficult it is to work on the cataract. In these cases, many surgeons will use a Malyugin ring. It is a small spring made of plastic that is temporarily injected into the eye to keep the pupil wide open (with a mild amount of iris stretching) until the surgery is completed. At the end of the surgery, the ring is removed to allow the pupil to constrict back to its normal size. This is a simple yet elegant technique that is also useful in cases of floppy iris syndrome as the ring keeps the iris from moving around during surgery.
Maxitrol. This is a combination of neomycin/polymyxin (antibiotics) and dexamethasone (a mild steroid). This antibiotic combination comes in both drop and ointment forms and is useful for mild infection or inflammation such as blepharitis. Some people are sensitive to the neomycin and may require more expensive alternative drugs like Tobradex or Zylet. Maxitrol is generic and on the $4 generic list at Walmart.
meibomian glands. These are small glands that run along the edge of the upper and lower eyelid. Meibomian glands produce oil that is continuously excreted into the tear film. This oil keeps the tears slippery and also forms a protective "evaporation proof" barrier on the surface of the tear film. The meibomian gland pore openings are small, and can't easily be seen without a microscope. If a meibomian gland pore gets clogged, the oil can back up into the eyelid and form a chalazion. Chalazions will sometimes spontaneously drain with the use of warm compresses and massage but will sometimes require surgical drainage in the office. Blepharitis is a condition where chronic eyelid irritation makes the eyes look puffy and feel sandy. Blepharitis also tends to clog themeibomian glands, which is why warm compresses and massage are often recommended for this condition as well ... to keep the meibomian glands flowing properly.
membrane peel. This is a surgery performed by a retinal specialist to remove an epiretinal membrane from the eye. An epiretinal membrane is a clear membrane that can form on the retina. While normally innocuous, this membrane may contract and can make the retinal surface "wrinkled" leading to vision loss. With a membrane peel surgery, the retina doctor goes into the eye and gently peels this membrane off to relieve traction. Then, a gas bubble is typically injected into the eye. This gas bubble lasts for several weeks and is designed to gently press on the retina and flatten the retina back into a smooth configuration. Since gas floats, a patient may be required to keep their head in a downward position for several weeks. This positioning can be a little harsh on the body, and patients come back to our office looking a little disheveled. This inconvenience is worth it if some vision is regained. Membrane peel surgery is not always successful, so most retina doctors like to wait until the vision deteriorates to a point they feel that the "benefits outweigh the risks" for the operation.
metal foreign body. This is a piece of metal in the eye, and is commonly caused while grinding or working on machinery. Small pieces of metal can fly or fall into the eye, and for some reason, metal likes to stick to the clear cornea. When this happens, the metal will embed into the eye and rust into place (the tear film is rather salty). Metal in the eye is painful and if not removed promptly, can lead to infection and scarring with potential long-term visual consequences. Sometimes, a piece of metal can be wiped off with a cotton swab, but often it requires more aggressive debridement. Typically, we'll numb the eye with topical anesthesia drops. Then, a small metal pick (like a needle, but not sharp) is used to wipe the piece off the cornea. If there is residual rust or metal fragments, this may need to be removed with a high-speed rotary tool like a microscopic dremel tool. This is all done sitting up at the exam chair, and while most people are understandably nervous, the whole procedure is surprisingly pain-free. Afterwards, we treat with antibiotics and recheck the eye over the next week to make sure no infection occurs. If, based on history and exam findings, we are concerned about a piece of metal actually penetrating the eye ... then a more involved examination is done. This may require a CAT scan to rule out metal pieces inside the eyeball.
methazolamide. Also known by the trade name Neptazane, this is a water pill used in the treatment of glaucoma. It is a carbonic anhydrase inhibitor that works by decreasing the production of aqueous fluid inside the eye. This medicine has the same mechanism of action of Diamox (acetazolamide).
migraine aura. This is a visual distortion that can occur during or before a migraine headache. Migraines are bad headaches associated with sensitivity to light or sound (and often nausea). Like most headaches, the underlying mechanism is not entirely understood but migraines may occur because of spasm of blood vessels in the brain. With some people, the spasming vessels occur at the back of the brain near the occipital cortex. This is the part of the brain that processes our vision, and when irritated, the occipital cortex can create visual hallucinations. Most people describe an "aura" to their vision where the center of their vision (or perhaps more to the side) becomes blurry. They may see lights, sparkles, or geometric distortions like a kaleidoscope. These visual changes tend to expand and spread to one side before subsiding after 15 to 30 minutes. Afterwards, some people get the traditional migraine headache, but other people have the visual symptoms alone with no residual discomfort. Migraine auras can be scary but are rarely serious. Some people are worried when their visual symptoms "change sides" and occur on the other half of the vision. This is actually a good sign, however, as variation is typical for migraines. It's when you have the same visual phenomenon over and over, always in the same place that we have to consider other possibilities like a mass lesion that is tickling the occipital lobe in one spot. In these cases, an MRI is obtained.
monocular precautions. Many people have only one good eye. Despite this limitation, they live perfectly rich and normal lives. We recommend these fine people take extra precautionary steps to keep their good eye "healthy." For example, if a rock randomly strikes you in the eye you don't have a backup eye to rely on. Conversely, if you get in a car accident, it would be nice to have some additional protection from flying glass. Monocular precautions usually involves safety glasses or getting your prescription glasses made of polycarbonate plastic (which acts like safety glass). If you wear contacts, then good hygiene becomes especially important as you don't want to get an infection in your only eye.
monovision. With monovision, one eye is set for distance vision while the other is set for near. Many contact lens wearers use a “monovision contact prescription” to avoid reading glasses. Most will set their dominant eye for distance and their non-dominant eye set for reading. While some people tolerate this imbalance well, other people hate monovision. The disparity between their eyes makes them sick to their stomach and unsteady on their feet. The blur at distance ruins their depth perception for driving, and reading becomes a chore because one eye is doing all the work. With LASIK or cataract surgery we have the opportunity to change your eyes' prescription. Some people choose to have monovision after surgery as they have tolerated it well in the past.
Moxeza. This is the trade name for the antibiotic moxifloxacin. This is a powerful antibiotic eye drop commonly used after cataract surgery and for more serious eye infections (such as a corneal ulcer in a contact lens wearer).
moxifloxacin. This is a powerful fluoroquinolone antibiotic eye drop, commonly used after cataract surgery and more serious eye infections (especially in contact lens wearers). This antibiotic is available under the trade names Vigamox and Moxeza.
MRI. MRI stands for magnetic resonance imaging. An MRI uses a large magnet and radio fields to view the interior body. MRI is particularly good at imaging soft tissues like the brain, but has limited use for looking at the eye itself. Some scientists estimate that a third of the brain is involved with vision in some way. Therefore, we obtain an MRI in cases of unexplained visual field loss or with cranial nerve palsies to look for tumors, mass lesions, and signs of stroke.
multifocal contact. This is a contact lens that is designed to improve both distance and near vision. The contact has separate zones of focus to accomplish this, arranged in a concentric ring like a fresnel lens. The downside to multifocal contacts is that they may not work perfectly for everyone and they are not quite as clear as a regular contact or glasses. The alternative is monovision, with one eye set for distance and the other set for near.
multifocal implant. This is an implant used during cataract surgery that may eliminate the need for reading glasses. With cataract surgery, the cloudy lens inside the eye is removed and replaced with a plastic implanted lens. The standard implant most people choose is focused for distance vision. These people continue to need bifocals or reading glasses after surgery for near vision. New "premium" implants are now available that have a bifocal built into them. There are different zones built into the implant surface that focus at different distances. These "multifocal implants" have more out-of-pocket expense than a standard lens because insurance companies will not pay for the additional cost. Not everyone is a good candidate for this type of lens as there are some small tradeoffs with multifocal implants. They may not be as crisp as a traditional lens and many people see ring-halos at night. Currently, the leading multifocal implant on the market is the Restor lens. A competing product called the Crystalens gives a similar focal effect, but works by a completely different mechanism. Most surgeons have a preference on the type of implant they use.
multiple sclerosis. An inflammatory disorder of the nervous system characterized by multiple neurologic symptoms over time. Multiple sclerosis (MS) occurs because of inflammation of the nerves in the body and brain. A myelin sheath normally surrounds the nerves in the body, acting just like the "insulation" on electrical wires. With MS, inflammation causes this insulation to break down, effectively "short circuiting" the normal nerve transmission. The eye is one of the areas most often affected as the optic nerve contains over a million individual nerve fibers. Inflammation in this nerve causes vision problems - this is called optic neuritis and is often one of the first symptoms of MS.
Muro 128. This is a hyperosmotic (lots of salt) eye drop that is used in cases of corneal edema. The cornea (the clear structure that makes up the front of our eye) is clear because it is relatively dry. With certain conditions such as Fuchs' dystrophy or after cataract surgery, the cornea can become wet and cloudy. Muro drops and ointments can be used to dry the eye out. Because this drop has a high salt content, water is attracted to it and the drop literally sucks or pulls water out of the cornea. Muro isn't really a drug so you don't necessarily need a prescription for it. However, pharmacists keep it behind the counter and so a prescription is usually written anyway.
myasthenia gravis. This is a rare autoimmune disease that causes easy fatigue of muscles throughout the body. When muscle fatigue occurs in the eye, this creates intermittent double vision (diplopia) and droopy eyelids (ptosis), especially when tired later in the day. The mechanism of this disorder involves the body developing antibodies to its own muscle nerve receptors. The eye muscles seem to be especially susceptible to this fatigue and this disorder is often first diagnosed at the eye doctor's office. More definitive diagnosis is made by a neurologist who looks for certain blood markers and performs electrical muscle stimulation tests. Primary doctors are also involved to check thyroid levels and insure the thymus gland is healthy.
Mydriacyl. This is the trade name for the dilating drop tropicamide. This is a short-acting dilating drop used during an eye exam to dilate the pupil. This drop also has cycloplegia effects which means that it will cause a fair amount of blurriness (especially with reading). It is the shortest acting dilator available, but even so, the dilation/blur can last anywhere from 3-8 hours.
myopia. This is another way of saying an eye is nearsighted. See the entry of nearsightedness for more information.
macula. The macula is the part of the retina that is responsible for our fine central vision. This is the vision necessary for reading a book, watching television, or seeing distant road signs. The retina works like film in a camera, and the macula is the most sensitive part of the film, containing more rod and cone photoreceptors than elsewhere. Problems at the macula, such as diabetic retinopathy or macular degeneration, can cause severe visual changes (though the peripheral vision remains intact). The macula can be viewed through dilation. The macula can also be measured using OCT photographs to look for swelling or sub-retinal bleeding. When there are problems, such as wet macular degeneration, the circulation under and around the macula can be further imaged using fluorescein angiogram (though this type of testing is usually left to retinal specialists).
macular degeneration. Macular degeneration is premature aging of the retina. The retina is located in the back of the eye and works like "the film in a camera," detecting light and images. The macula is the central retina responsible for fine central vision. If the macular retina wears down this can cause serious problems. For most people, this results in difficulty seeing fine details such as small type in books ... though ARMD can cause serious vision loss when advanced. Most people have dry macular degeneration where the vision slowly worsens with time. Treatment for dry degeneration is limited, and revolves around using eye vitamins and vision screening with an Amsler grid at home and OCT scans at our office. Some people go on to develop wet macular degeneration where the retinal blood vessels leak fluid and this can lead to rapid vision loss. Wet degeneration causes significant vision changes, but there are also more treatment options such as anti-VEGF injections and laser. Wet degeneration can be detected with OCT scans and leaky areas further localized using fluorescein angiography.
macular edema. This is swelling of the macula, the area of the retina that is responsible for our fine central vision. The retina can be thought of like film in a camera. Just like film, the retina needs to be perfectly smooth and flat if we are going to "take a good picture" and see clearly. If there is swelling at the macula, then the "film" becomes distorted in the middle and this creates blur or distortion to the central vision as well. There are many causes of macular edema, such as leaking
vessels from wet macular degeneration, diabetic retinopathy, or traction from epiretinal membranes. Retinal edema can be detected in our office using OCT photographs to map out the retinal surface. Early retinal changes may even be detected at home using an Amsler grid. Treatment for this condition depends upon the cause, but usually involves injections of anti-inflammatory medications (such as Kenalog or Avastin) if there is active bleeding or if the edema is not resolving.
macular hole. This is a small hole that forms in the macula that creates significant vision problems. The retina is located in the back of the eye and acts like film in a camera. The macula is the most important part of the retina as it is responsible for our fine central vision. If a hole forms in this area, the central vision "goes to pot." There are several causes for a macular hole. One is an epiretinal membrane. This is a clear fibrous membrane that can form on the surface of the retina with age (and sometimes after trauma). This membrane can contract like "shrinkwrap plastic" and cause traction on the retinal surface. This creates wrinkles on the surface of the retina and if bad enough, can pull open a full-thickness hole in the macula. A hole can also form from the traction of a vitreous detachment. The vitreous is the gel that fills the rear chamber of the eye. The vitreous has a tendency to contract and collapse inwards with age, tugging on the retina. This can create retinal tears or holes and lead to a retinal detachment. If this tugging occurs at the macula, a full thickness hole can result. Macular holes, if small enough, may close on their own but often require surgical correction. This usually involves a membrane peel surgery. In this surgery, a retina specialist will enter through the back of the eye and remove the source of the traction (i.e., remove the epiretinal membrane or vitreous jelly). Then, a gas bubble is injected into the eye in order to smooth out the retina, and (hopefully) the hole will close over the next several weeks. Though a commonly performed surgery, membrane peels are not always successful. A macular hole causes central vision distortion that can be detected with an OCT scan of the retina. Amsler grid monitoring at home may pick up an early macular hole as well, but definitive diagnosis is made in the doctor's office.
macular pucker. This is a membrane that forms on the surface of the retina that causes it to wrinkle or "pucker." Other names for this are epiretinal membrane and cellophane retinopathy. See the entry on epiretinal membrane for a more detailed explanation of this common finding.
Malyugin ring. This is a small spring-like device used during cataract surgery to help dilate the pupil. Small pupils make cataract surgery difficult, as the procedure involves vacuuming out the cataract "through" the pupil. Some people have naturally small pupils (the black hole in the middle of the iris) and don't dilate well. Poor dilation may be genetic or occur from atrophy of the iris muscle that occurs with age. The smaller the pupil, the more difficult it is to work on the cataract. In these cases, many surgeons will use a Malyugin ring. It is a small spring made of plastic that is temporarily injected into the eye to keep the pupil wide open (with a mild amount of iris stretching) until the surgery is completed. At the end of the surgery, the ring is removed to allow the pupil to constrict back to its normal size. This is a simple yet elegant technique that is also useful in cases of floppy iris syndrome as the ring keeps the iris from moving around during surgery.
Maxitrol. This is a combination of neomycin/polymyxin (antibiotics) and dexamethasone (a mild steroid). This antibiotic combination comes in both drop and ointment forms and is useful for mild infection or inflammation such as blepharitis. Some people are sensitive to the neomycin and may require more expensive alternative drugs like Tobradex or Zylet. Maxitrol is generic and on the $4 generic list at Walmart.
meibomian glands. These are small glands that run along the edge of the upper and lower eyelid. Meibomian glands produce oil that is continuously excreted into the tear film. This oil keeps the tears slippery and also forms a protective "evaporation proof" barrier on the surface of the tear film. The meibomian gland pore openings are small, and can't easily be seen without a microscope. If a meibomian gland pore gets clogged, the oil can back up into the eyelid and form a chalazion. Chalazions will sometimes spontaneously drain with the use of warm compresses and massage but will sometimes require surgical drainage in the office. Blepharitis is a condition where chronic eyelid irritation makes the eyes look puffy and feel sandy. Blepharitis also tends to clog themeibomian glands, which is why warm compresses and massage are often recommended for this condition as well ... to keep the meibomian glands flowing properly.
membrane peel. This is a surgery performed by a retinal specialist to remove an epiretinal membrane from the eye. An epiretinal membrane is a clear membrane that can form on the retina. While normally innocuous, this membrane may contract and can make the retinal surface "wrinkled" leading to vision loss. With a membrane peel surgery, the retina doctor goes into the eye and gently peels this membrane off to relieve traction. Then, a gas bubble is typically injected into the eye. This gas bubble lasts for several weeks and is designed to gently press on the retina and flatten the retina back into a smooth configuration. Since gas floats, a patient may be required to keep their head in a downward position for several weeks. This positioning can be a little harsh on the body, and patients come back to our office looking a little disheveled. This inconvenience is worth it if some vision is regained. Membrane peel surgery is not always successful, so most retina doctors like to wait until the vision deteriorates to a point they feel that the "benefits outweigh the risks" for the operation.
metal foreign body. This is a piece of metal in the eye, and is commonly caused while grinding or working on machinery. Small pieces of metal can fly or fall into the eye, and for some reason, metal likes to stick to the clear cornea. When this happens, the metal will embed into the eye and rust into place (the tear film is rather salty). Metal in the eye is painful and if not removed promptly, can lead to infection and scarring with potential long-term visual consequences. Sometimes, a piece of metal can be wiped off with a cotton swab, but often it requires more aggressive debridement. Typically, we'll numb the eye with topical anesthesia drops. Then, a small metal pick (like a needle, but not sharp) is used to wipe the piece off the cornea. If there is residual rust or metal fragments, this may need to be removed with a high-speed rotary tool like a microscopic dremel tool. This is all done sitting up at the exam chair, and while most people are understandably nervous, the whole procedure is surprisingly pain-free. Afterwards, we treat with antibiotics and recheck the eye over the next week to make sure no infection occurs. If, based on history and exam findings, we are concerned about a piece of metal actually penetrating the eye ... then a more involved examination is done. This may require a CAT scan to rule out metal pieces inside the eyeball.
methazolamide. Also known by the trade name Neptazane, this is a water pill used in the treatment of glaucoma. It is a carbonic anhydrase inhibitor that works by decreasing the production of aqueous fluid inside the eye. This medicine has the same mechanism of action of Diamox (acetazolamide).
migraine aura. This is a visual distortion that can occur during or before a migraine headache. Migraines are bad headaches associated with sensitivity to light or sound (and often nausea). Like most headaches, the underlying mechanism is not entirely understood but migraines may occur because of spasm of blood vessels in the brain. With some people, the spasming vessels occur at the back of the brain near the occipital cortex. This is the part of the brain that processes our vision, and when irritated, the occipital cortex can create visual hallucinations. Most people describe an "aura" to their vision where the center of their vision (or perhaps more to the side) becomes blurry. They may see lights, sparkles, or geometric distortions like a kaleidoscope. These visual changes tend to expand and spread to one side before subsiding after 15 to 30 minutes. Afterwards, some people get the traditional migraine headache, but other people have the visual symptoms alone with no residual discomfort. Migraine auras can be scary but are rarely serious. Some people are worried when their visual symptoms "change sides" and occur on the other half of the vision. This is actually a good sign, however, as variation is typical for migraines. It's when you have the same visual phenomenon over and over, always in the same place that we have to consider other possibilities like a mass lesion that is tickling the occipital lobe in one spot. In these cases, an MRI is obtained.
monocular precautions. Many people have only one good eye. Despite this limitation, they live perfectly rich and normal lives. We recommend these fine people take extra precautionary steps to keep their good eye "healthy." For example, if a rock randomly strikes you in the eye you don't have a backup eye to rely on. Conversely, if you get in a car accident, it would be nice to have some additional protection from flying glass. Monocular precautions usually involves safety glasses or getting your prescription glasses made of polycarbonate plastic (which acts like safety glass). If you wear contacts, then good hygiene becomes especially important as you don't want to get an infection in your only eye.
monovision. With monovision, one eye is set for distance vision while the other is set for near. Many contact lens wearers use a “monovision contact prescription” to avoid reading glasses. Most will set their dominant eye for distance and their non-dominant eye set for reading. While some people tolerate this imbalance well, other people hate monovision. The disparity between their eyes makes them sick to their stomach and unsteady on their feet. The blur at distance ruins their depth perception for driving, and reading becomes a chore because one eye is doing all the work. With LASIK or cataract surgery we have the opportunity to change your eyes' prescription. Some people choose to have monovision after surgery as they have tolerated it well in the past.
Moxeza. This is the trade name for the antibiotic moxifloxacin. This is a powerful antibiotic eye drop commonly used after cataract surgery and for more serious eye infections (such as a corneal ulcer in a contact lens wearer).
moxifloxacin. This is a powerful fluoroquinolone antibiotic eye drop, commonly used after cataract surgery and more serious eye infections (especially in contact lens wearers). This antibiotic is available under the trade names Vigamox and Moxeza.
MRI. MRI stands for magnetic resonance imaging. An MRI uses a large magnet and radio fields to view the interior body. MRI is particularly good at imaging soft tissues like the brain, but has limited use for looking at the eye itself. Some scientists estimate that a third of the brain is involved with vision in some way. Therefore, we obtain an MRI in cases of unexplained visual field loss or with cranial nerve palsies to look for tumors, mass lesions, and signs of stroke.
multifocal contact. This is a contact lens that is designed to improve both distance and near vision. The contact has separate zones of focus to accomplish this, arranged in a concentric ring like a fresnel lens. The downside to multifocal contacts is that they may not work perfectly for everyone and they are not quite as clear as a regular contact or glasses. The alternative is monovision, with one eye set for distance and the other set for near.
multifocal implant. This is an implant used during cataract surgery that may eliminate the need for reading glasses. With cataract surgery, the cloudy lens inside the eye is removed and replaced with a plastic implanted lens. The standard implant most people choose is focused for distance vision. These people continue to need bifocals or reading glasses after surgery for near vision. New "premium" implants are now available that have a bifocal built into them. There are different zones built into the implant surface that focus at different distances. These "multifocal implants" have more out-of-pocket expense than a standard lens because insurance companies will not pay for the additional cost. Not everyone is a good candidate for this type of lens as there are some small tradeoffs with multifocal implants. They may not be as crisp as a traditional lens and many people see ring-halos at night. Currently, the leading multifocal implant on the market is the Restor lens. A competing product called the Crystalens gives a similar focal effect, but works by a completely different mechanism. Most surgeons have a preference on the type of implant they use.
multiple sclerosis. An inflammatory disorder of the nervous system characterized by multiple neurologic symptoms over time. Multiple sclerosis (MS) occurs because of inflammation of the nerves in the body and brain. A myelin sheath normally surrounds the nerves in the body, acting just like the "insulation" on electrical wires. With MS, inflammation causes this insulation to break down, effectively "short circuiting" the normal nerve transmission. The eye is one of the areas most often affected as the optic nerve contains over a million individual nerve fibers. Inflammation in this nerve causes vision problems - this is called optic neuritis and is often one of the first symptoms of MS.
Muro 128. This is a hyperosmotic (lots of salt) eye drop that is used in cases of corneal edema. The cornea (the clear structure that makes up the front of our eye) is clear because it is relatively dry. With certain conditions such as Fuchs' dystrophy or after cataract surgery, the cornea can become wet and cloudy. Muro drops and ointments can be used to dry the eye out. Because this drop has a high salt content, water is attracted to it and the drop literally sucks or pulls water out of the cornea. Muro isn't really a drug so you don't necessarily need a prescription for it. However, pharmacists keep it behind the counter and so a prescription is usually written anyway.
myasthenia gravis. This is a rare autoimmune disease that causes easy fatigue of muscles throughout the body. When muscle fatigue occurs in the eye, this creates intermittent double vision (diplopia) and droopy eyelids (ptosis), especially when tired later in the day. The mechanism of this disorder involves the body developing antibodies to its own muscle nerve receptors. The eye muscles seem to be especially susceptible to this fatigue and this disorder is often first diagnosed at the eye doctor's office. More definitive diagnosis is made by a neurologist who looks for certain blood markers and performs electrical muscle stimulation tests. Primary doctors are also involved to check thyroid levels and insure the thymus gland is healthy.
Mydriacyl. This is the trade name for the dilating drop tropicamide. This is a short-acting dilating drop used during an eye exam to dilate the pupil. This drop also has cycloplegia effects which means that it will cause a fair amount of blurriness (especially with reading). It is the shortest acting dilator available, but even so, the dilation/blur can last anywhere from 3-8 hours.
myopia. This is another way of saying an eye is nearsighted. See the entry of nearsightedness for more information.