(301) 281-6831

facebook-square twitter-square instagram chevron-right chevron-left chevron-down x phone location share chevron-thin-right calendar left-quote right-quote black-star-glasses-png eye book-appointment-maroon-icon-(1) types-of-services-white-icon-(1) location-white-icon next2 previous2 forward3 backward2

Rockville, MD
(301) 670-1212

Eye and Vision Care Glossary

When your eyes look at objects up close, such as a newspaper or a PDA, each eye must focus for the distance at which the object is held. The closer an object is, more focusing power is necessary to see it clearly.
Physiologically the lens of the eye changes its shape and that shape change results in focus, or “accommodation”. The two eyes must also simultaneously point to the object, also called “converging”. Although convergence and accommodation are separate functions, they are tied together. Challenges with one create challenges with the other.

Difficulty focusing your eyes can result in blur, eye strain, headaches, reduced vision, double vision, trouble seeing at near, intermittent focusing difficulties and eyestrain and fatigue.

The causes of accommodative problems include over or under focusing, over or under convergence of the eyes, eye muscle imbalnances and a host of other things. Also, the ability to change focus for near is reduced with age. Presbyopia (as the aging change that historically is know to result in a need for bifocals is called), affects all people, usually after the age of 42, however this is an age related change and not technically an “accommodative” dysfunction, which plagues people of younger ages generally. Other things that can cause focusing problems include neurological diseases, emotional disorders, incorrect eyeglass or contact lens prescriptions, stress or side effects of certain medications.

Treatment for focusing issues can include specially prescribed lenses, which supplement the focusing power necessary to see clearly. In many cases, specially prescribed visual therapy may be needed to teach the eyes to change focus comfortably. Frequently, both therapy and glasses are necessary.

In order to look at near (reading, hobbies etc) each eye must change focus using a process called accommodation. Accommodative insufficiency means the eyes lack the ability to sustain this focus or to change focus efficiently from near to far and back.

Accommodative insufficiency causes of blurred vision, headaches, and eyestrain. It also can cause difficulties in transitioning clear vision from distance focus to near and back (fluctuating vision). Treatment for accommodative difficulties may include specially prescribed lenses, and in some, cases vision therapy training.

Accommodation is the ability of the eye to change focus when shifting vision from far to near objects. Disaccommodation, or unaccomodation is the act of changing focus when shifting from near to far objects. Accommodative spasm is when the eye “overfocuses”, or “locks in” when looking at near and has difficulty releasing to see far vision clear when attempting to transition back.

Symptoms can include trouble performing near vision tasks, blurred vision at varying distances, the holding of reading material or other work closer than expected, headaches, eye strain and possible double vision. People with these spasms frequently will have rapidly advancing prescriptions in their eyeglasses.

Treatment might involve the prescription of lenses to reduce the overstimulation and/or specifically prescribed visual therapy procedures. If this condition is left unresolved, increases in nearsightedness may occur.

Allergic conjunctivitis is when allergens, either in the air or through contact, inflame the conjunctiva, or clear surface of the white part of the eye or the pink part of the inner eyelid. Symptoms include itching, tearing, and swelling.

Treatment of allergic conjunctivitis may include anti-inflammatory, antihistamine and decongestant eye drops. Doctors might recommend cool compresses and, of course if an option, removal of the offending allergen. There are many effective mast cell stabilizer/antihistamine combination medications that can help resolve symptoms with as few as one drop per day, so be sure to see your doctor if you suffer from seasonal allergies and/or seasonal allergic conjunctivitis. The contact form of allergic conjunctivitis usually affects only one eye while the non-contact form affects both.

Also called “Lazy Eye”, amblyopia indicates as less-than-perfect connection between the eye and the brain. Eyes with amblyopia cannot be corrected to better than 20/25 with any type of lens. In other words, an eye with amblyopia has a limit to what it can see regardless of lenses or surgery.

The most common causes of amblyopia due to conditions like strabismus (the eyes not pointing in the same direction) where they never develop the ability to see together and by favoring one eye cause the other to wither in a manner analogous to a leg in a cast. They can be congenital, meaning it is the way someone is born, or it can develop for many reasons where one eye is deprived of vision while the other eye continues to be used.

A young child has a much better chance at gaining normal vision than that of an older child, adolescent or adult. Treatment includes eyeglasses, patching or occluding the normal eye to force the amblyopic eye to work, and sometimes vision therapy. Eye doctors used to think amblyopia treatment had little benefit after the visual system matures, but recent research has shown even adults can benefit from amblyopia therapy to some extent. Amblyopia is best treated before age 8, although treatment can help in older children and adolescents

When you have a significant difference in prescriptions between both eyes. These significant differences in power between the two eyes (usually more than -1.25 difference in prescription between the two) may cause symptoms of strain, double vision, poor depth perception or blurry vision. Anisometropia may also create a differential in the thickness between eyeglass lenses in terms of their thickness. In many cases, your brain will adjust to these differences. Sometimes it won’t and people can experience suppression of vision in one eye or double vision because of the steep differential. Occasionally, contact lenses or refractive surgery may be helpful if you cannot adapt to your eyeglasses. The latest treatment for anisometropia is a lens called the Shaw Lens, which enables the different eyes to receive similar sized images, increasing comfort of “two eyed” (binocular) vision.

Arcus is an accumulation of lipids in the periphery of the cornea (front surface) of the eye. It is common and may have an association with elevated blood cholesterol. Should one be diagnosed with Arcus a physical and blood lipid profile is in order.

Astigmatism can occur when simply the front surface of the eye (cornea) or it’s internal lens has more than one curvature, rather than a perfectly round shape. With astigmatism, the shape of the optical elements of the eye are asymmetrical, or somewhat “football” shaped, rather than uniformly round like a sphere. Focusing for astigmatism requires a different power at each angle, or axis – one axis a nearsighted powered lens and one a farsighted lens. This is achieved by placing a cylindrical or aspheric lens in front of the eye.

Uncorrected or incorrect prescriptions for astigmatism cause blurred and tilted vision, and may lead to eyestrain, headaches, fatigue, sensitivity to light, and trouble concentrating

When one is diagnosed with astigmatism and gets new eyeglasses, objects can appear tilted and/or distorted. This perception of distortion will decrease steadily with time as one adapts, unless the prescription is inaccurate. It may take up to two weeks in some cases to adapt. Astigmatism prescriptions change over time, so regular eye examinations are important to monitor these changes and correct eyewear appropriately. Eyeglasses, and/or, special astigmatic (toric) contact lenses are available to correct astigmatism. LASIK can correct astigmatism as well. Around 87% of all eyeglass prescriptions contain some correction for astigmatism.

When the clear lining above the white part of the eye, called the conjunctiva, is infected by bacteria, it is called bacterial conjunctivitis.

Symptoms of bacterial conjunctivitis include redness, irritation and a discharge (mucous) that may build up along the eyelashes. Eyes with bacterial conjunctivitis have a tendency to stick together, especially in the morning, and there is rarely any pain. Bacterial conjunctivitis is highly contagious, yet easily treated. Most bacterial infections are treated with antibiotic eye drops. Contact lenses cannot be worn until the treatment has successfully completed.

Corneal ulcers occur when a pathogen (fungus, amoebae or bacteria) takes advantage of a weakened corneal surface and creates an infection. Most corneal ulcers are the result of bacterial infection, but some more serious ones are caused by fungus or amoebae. Symptoms of corneal ulcers are often mistaken for eye scratches and abrasions and include pain, sensitivity to light, foreign body sensation, decreased vision among others.

All corneal ulcers require immediate treatment and monitoring and have the potential to permanently reduce sight. Treatment usually involves antibiotics, and sometimes anti-inflammatory medications. Scarring to the cornea may result despite treatment. Frequent examination by an eye doctor is necessary until the ulcer is completely healed. Contact lenses must be discontinued in most cases and treatment can take 2 weeks or more.

Freckle-like pigmented spots on the outer eye surface (conjunctiva) are called nevi or melanosis. Like freckles, these are some of the most common benign tumors and pigmentations of the eye surface. Nevi are considered to be congenital lesions that are generally first identified in early adulthood. Both conjunctival nevi and melanosis, like freckles, are caused by excess skin pigmentation (melanin) but on occasion can form because of something else.

Your eye doctor will monitor these pigmentations to ensure they don’t change in shape, size or coloration. If they are stable, they are of as much concern as a freckle. However, a change in any of these features should be observed as soon as possible by a doctor and can indicate a serious condition generally successfully treated if caught early.

Our eyes maintain a “position” when viewing objects at different distances. When one is asleep, the eyes go to their resting position, and when one awakes and looks at an object of regard, let’s say at 20 feet away, the eyes “converge” on that object. Objects 20 feet and greater have minimal convergence; in other words, the eyes are aligned somewhat parallel, and as we go to view nearer objects, the eyes converge together.

Eyes that are turned slightly inward and require a small muscle tension to keep the distance parallel alignment are said to have an “eso” posture. Eso postured eyes that turn in too much might converge too much when looking at near objects and this is termed convergence excess.

Eyes with convergence excess might experience eyestrain, difficulty focusing on distance objects and/or rapidly increasing nearsightedness. Convergence excess is generally treated by prescribing reading glasses or bifocals, which help to align the eyes and reduce symptoms and in some cases worsening nearsightedness.

Our eyes maintain a “position” when viewing objects at different distances. When one is asleep, the eyes go to their resting position, and when one awakes and looks at an object of regard, let’s say at 20 feet away, the eyes “converge” on that object. Objects 20 feet and greater have minimal convergence; in other words, the eyes are aligned somewhat parallel, and as we go to view nearer objects, the eyes converge together.

Eyes that are turned slightly outward and require a small muscle tension to keep the distance parallel alignment are said to have an “exo” posture. Exo postured eyes that turn out too much might have trouble turning in to view near objects and this is termed convergence insufficiency. It is a type of eye muscle imbalance.

Convergence insufficients can have eyestrain when attempting to sustain near vision in activities like reading and studying. Some are prone to headaches from near point activities and others may experience intermittent blurry vision when trying to read. Some convergent insufficients must cover one eye to read as both eyes won’t efficiently turn in together, or they will find other ways of compensating so they reduce eyestrain and double vision.

Treatment of convergence insufficiency generally takes the form of vision therapy to strengthen the muscles that “turn in” the eyes.

Corneal abrasions are “scratches” to the clear, domed shape surface of the eye called the cornea. Symptoms of corneal abrasions include pain, sensitivity to light (photophobia), foreign body sensation, tearing and possibly vision decrease or a combination of these symptoms.

Corneal abrasions are treated with bedrest, non-steroidal anti-inflammatories (for pain), patching of the eye or a contact lens that is used like a bandaid (bandage contact lens). Some abrasions are treated with antibiotics as well to prevent infection. The cornea heals rapidly and most symptoms are resolved within a 24 hour period of obtaining the scratch.

A dellen is an area of thinning of the peripheral cornea. The cornea is the clear outer window of the eye. Dellen usually occur secondary to chronic eye dryness.

Treatment of dellen includes moisturing eye drops, anti-inflammatories and gels that keep the eye moist while one sleeps.

The cornea is the clear front “shield” of the eye and comprised of 5 or 6 layers of tissue. The cornea must remain transparent for good vision – There is a gradient of water that is maintained throughout the cornea by the layer of cells most posterior to it, the endothelium. If the endothelium is disrupted, or the outer layer, the epithelium is compromised, swelling of the tissue might occur and it is called corneal edema.

Causes of corneal edema include but are not limited to infections, surgery, injury and insult, contact lens over-wear, poor fitting contact lenses, old contact lenses or contact lens complications, increased eye pressure and exposure to toxins.

Early symptoms of corneal edema may be distorted or blurred vision, halos around light, eye discomfort and sensitivity to light.

Treatment varies based on the cause of the condition. When contact lenses are the culprit, reduced wear time, discontinuation of wear or change in lens type may be required. Corneal edema caused by increased eye pressure is an emergency and must be treated by lowering the eye pressure.

If corneal swelling is restricted to the outer layer of the cornea, it can be treated by using a saline eye drop or gel (Muro, Bausch & Lomb) which helps to remove excess fluid accumulation in the cornea.

Emmetropia indicates someone has perfect eyesight when viewing objects at 20 feet (6 Meters) or further. Eyes that are “emmetropic” still must be evaluated annually by an eye doctor. Many eye diseases don’t change the visual status of the eye until it is too late, so regular eye examinations are recommended to ensure eye health even if vision is emmetropic.

Our eyes maintain a “position” when viewing objects at different distances. When one is asleep, the eyes go to their resting position, and when one awakes and looks at an object of regard, let’s say at 20 feet away, the eyes “converge” on that object. Objects 20 feet and greater have minimal convergence; in other words, the eyes are aligned somewhat parallel, and as we go to view nearer objects, the eyes converge together.

Eyes that are turned slightly inward and require a small muscle tension to keep the distance parallel alignment are said to have an “esophoric” posture. Eyes with esophoria which turn in too much might converge too much when looking at near objects and this is termed convergence excess.

Eyes with esophoria might experience eyestrain, difficulty focusing on distance objects and/or rapidly increasing nearsightedness. Esophoria is generally treated by prescribing reading glasses or bifocals, which help to align the eyes and reduce symptoms and in some cases worsening nearsightedness.

Our eyes maintain a “position” when viewing objects at different distances. When one is asleep, the eyes go to their resting position, and when one awakes and looks at an object of regard, let’s say at 20 feet away, the eyes “converge” on that object. Objects 20 feet and greater have minimal convergence; in other words, the eyes are aligned somewhat parallel, and as we go to view nearer objects, the eyes converge together.

Eyes that are turned slightly outward and require a small muscle tension to keep the distance parallel alignment are said to have exophoria. Exophoric eyes that turn out too much might have trouble turning in to view near objects; extreme exophoria is termed convergence insufficiency.

Fuch’s Dystrophy is a loss of the corneal endothelium; the layer of cells of the cornea. The role of the endothelium is to keep this “window of the eye”, the cornea, clear. As cells are lost, swelling of the cornea occurs resulting in blurry vision, glare and trouble seeing at night time as well as shifting vision.

Fuch’s is a hereditary disorder which is chronic in nature. There is no totally effective cure, but certain eyedrops and now some surgeries can help some people with Fuchs . Advanced cases may need corneal surgeries involving new donor corneas and grafts.

The latin term for farsightedness is hyperopia, and this term is used by eye doctors to refer to vision where in some cases near vision is worse than far vision. Many young people with hyperopia can see well at near as well as at far and, with age, the ability to see both diminishes. Farsightedness and nearsightedness are both caused by the length of the eye. Farsighted eyes are generally shorter in axial length – the length from the front to back of the eye. An uncorrected farsighted eye actively has to focus to see near ranges and relaxes when viewing distance ranges. This can be comfortable and unnoticed for some and may lead to eyestrain, fatigue and other symptoms in others.

How well one sees at varying ranges depends on the degree of farsightedness a person has. Farsighted people’s ability to see near gradually diminishes as they move past the age of 40, a condition called Presbyopia.

Eyeglasses, contact lenses and laser vision correction such as PRK and LASIK are available to correct vision in farsighted people.

When the entire surface of the eye is infected we call it keratoconjunctivitis. The two tissues that make up the surface of the eye are the cornea (the clear domed shape surface of the front of the eye) and the conjunctiva (the thin, transparent layer of tissue over the white part of the eye. Keratoconjunctivitis is caused by infections, toxic chemicals, environmental irritants or allergies.

Symptoms include redness, swelling, light sensitivity, mucous and pain. Treatment of this condition varies depending on the cause but may involve antibiotics, antivirals and/or steroid eye drops.

Also known as Epithelial basement membrane dystrophy, map dot dystrophy is an inherited disorder of the outer layers of the clear front shield of the eye, the cornea. Areas of tissue disruption underneath the surface layer of the cornea migrate to the surface, causing blurred vision, light sensitivity, foreign body sensation, and sometimes sudden pain upon awakening. Treatment is aimed at relieving the symptoms by using special lubricating ointments, drops, gels, and sometimes, bandage contact lenses which protect the surface of the eye.

The latin term, and the term used by eye doctors for nearsightedness is myopia. Nearsighted people see better at near and worse at far. Nearsighted eyes are nearsighted because they are longer from front to back then farsighted eyes; they have a longer “axial length”. These eyes also may be nearsighted because they have a front surface (cornea) or lens that is too powerful, focusing light in front of the retina of an otherwise averaged sized eye. Myopia tends to change with time and methods have been identified to control the progression of myopia (Visit MyopiaInstitute.com for information on scientific methods proven or disproven in myopia control).

Nearsightedness is correctable with eyeglasses, contact lenses and refractive surgery such as PRK or LASIK. Most nearsightedness can also be corrected by reshaping the surface of the eye with special medical devices worn only during sleep, a method called Orthokeratology. For adults, refractive surgery such as LASIK, or lens replacements are additional options.

The eye can be thought of like a sink, with a drain and a faucet. The eyes “faucet” (ciliary body) creates water based fluid that fills up the eye and a structure known as the “angle” is the drain. If too much fluid is entering the eye or not enough leaving through the drain, the pressure in the eye can increase leading to one type of primary open angle glaucoma. Narrow angle glaucoma is when the angle is too narrow to let enough fluid leave the eye, causing the pressure inside to mount.

Treatment of narrow angle glaucoma is directed at lowering the pressure inside the eye using medications, but generally, laser treatment, a procedure known as an iridotomy or iridectomy (laser procedure) or surgery is required as well.

In order to read and see near and far objects clearly and move the eyes back and forth between objects of regard the eyes use what are called pursuit movements. The ability and necessity of the eyes to jump quickly between objects they are viewing is achieved through saccadic eye movements. An “oculo-motor dysfunction” defines a difficulty in the smooth movement of the eyes using one or both of these skills.

Symptoms of ocular-motor dysfunction include losing place while reading, leaving out letters and words when reading or writing and even word reversal. Sometimes poor readers and learners are diagnosed with attention problems when in fact they have an oculomotor dysfunction. OM Dysfunction can cause headaches, blurred vision, double vision, dizziness and eye fatigue. Neurological conditions such as stroke can also affect eye movement skills.

Treatment includes visual therapy techniques to help control the eye movements.

Presbyopia is the decline in the ability of our eyes to focus at near as we age. Our eyes have maximum focusing ability in our teens, less around age 40, and the gradual decline in this ability causes people to need reading glasses, bifocals or multifocal lenses (progressive lenses) by the time they are in their mid to late 40’s. Everyone who lives past the age of 45ish will experience presbyopia.

Presbyopia is a result of the loss of elasticity of the natural lens of the eye. The natural lens hardens over time, causing the muscles that focus the lens not to be able to change it’s shape for near vision more and more as we age. Wearing eyeglasses to correct the condition does not weaken the eye; it is necessary to maintain comfortable clear vision as a mature adult.

Presbyopia can be corrected with bifocals eyeglass lenses, multifocal eyeglass lenses, progressive eyeglass lenses and contact lenses. There are some surgeries that claim to offer relief from presbyopia but at this writing the only surgery that might help significantly is monovision treatment (one eye “set” by the laser for near and one eye for far) with LASIK or PRK.

Glaucoma is a condition wherein the nerve fibers that transmit vision from the eye to the brain start to die. There are many reasons this may occur including increased pressure in the eye and genetic predisposition, to name just two.

Primary open angle glaucoma (POAG) is the most common form of glaucoma. The eye can be thought of like a sink, with a drain and a faucet. The eyes “faucet” (ciliary body) creates water based fluid that fills up the eye and a structure known as the “angle” is the drain. If too much fluid is entering the eye or not enough leaving through the drain, the pressure in the eye can increase leading to one type of primary open angle glaucoma. Primary open angle glaucoma is a slowly progressive disease that must be diagnosed and treated early to avoid irreversible loss of vision. Treatment usually includes eye drops in the early stages, but can progress to require laser treatment and possible other surgeries. . Glaucoma is a silently blinding eye disease and people often report excellent vision close to end stage. For this reason, and because other eye diseases have a slow and insidious onset as well, regular eye exams are recommended to rule out silently blinding eye conditions like glaucoma so effective, preventive care can be administered by your eye doctor.

The surface of the white part of the eye has a thin clear film overlying it called the conjunctiva. In between this thin film and the white “sclera” below there are thin blood vessles. When one of these blood vessels break, a subconjunctival hemorrhage can occur. It is analogous to a bruise under the skin, but since the top layer is transparent, it looks red instead of purple.

Subconj hemes may be brought on by coughing, sneezing or lifting something heavy. It can also be caused by getting poked in the eye. High blood pressure and blood thinner-medications can contribute to the condition.

There is no specific treatment for this condition, but some people advocate cold compresses on the eyes. Aspirin can exacerbate the situation. It may take one to two weeks to completely clear. During this time the hemorrhage may spread and may change color from red, to brown, to yellow.

Strabismus is the latin name eye doctors use to describe an eye turn. When the eyes aren’t aligned, they can’t see together, and depth perception is lost. Strabismus can be “exo”, meaning one eye turns out while the other eye does the viewing, or “eso”, where the eyes cross in and one eye is turned in while the other does the viewing. Strabismus may also be the result of more serious conditions affecting the mid-brain including stroke and or space-occupying lesions like tumors or swelling of the brain or spinal cord.

Treatment may include glasses, prism lenses, eye muscle exercises (vision therapy), steroids or surgery.

A vertical eye muscle imbalance means the eyes don’t line up on the same plane. The direction of one eye is aimed “up” while the direction of the other eye is aimed straight ahead or vice versa. Uncorrected vertical deviations commonly cause headaches, neck pain, eyestrain, reading problems, and in some cases, double vision. Many people seeking treatment for neck and upper back problems are experiencing the problems because they tilt their head to align the two eyes, so the neck and upper back are strained so vision can remain clear and single.

Treatment of this condition may include special prismatic eyeglass lenses, eye muscle exercises (vision therapy), and in rare cases, surgery.

The vitreous is the clear gel that fills the eye and helps maintain its shape. The vitreous is composed of ultra-thin strands of collagen and other proteins that are less than one wavelength of light thick. This enables light to travel to the back of the eye unimpeded. On the end of the protein strands are sulfur molecules, spaced apart evenly so they don’t “stick” together. Should two sulfur molecules come in contact, they join together forming a disulfide bond. This bond causes the thin strands to wind up and spring together, creating strands that are thicker than one wavelength of light. These strands then cast a shadow on the retina which can be observed to shift and move when the eye shifts and move.

These “strands” or floaters as they are commonly called tend to come and go or increase with time. They may be easier viewed against a clear field like the sky or a wall painted one color. Floaters that have been present over a long period of time, or have increased very gradually, are generally harmless. However, new floaters, a sudden increase in the number of floaters, and/or, flashes of light which occur should be examined immediately by an eye doctor to rule out complications of the retina that can lead to a retinal tear or detachment.

Finding Our Location

We are located between Rockville and Gaithersburg, near the Adventist HealthCare Shady Grove Medical Center and the Johns Hopkins University Montgomery County Campus off West Montgomery Ave on Shady Grove Road. For more detailed driving instructions, see below.

Address

15200 Shady Grove Road, Suite 100
Rockville, MD, 20850

Contact Information

Phone: (301) 670-1212
Email: [email protected]

Shady Grove Care Hours

In addition to our office hours, we offer a 24-hour emergency answering service available to all established patients.

Monday: 9 AM - 1 PM, 2 PM - 7 PM
Tuesday: 9 AM - 12:30 PM, 2 PM - 7 PM
Wednesday: 9 AM - 1 PM, 2 PM - 7 PM
Thursday: 9 AM - 1 PM, 2 PM - 7 PM
Friday: 9 AM - 1 PM, 2 PM - 7 PM
Saturday: 9 AM - 2 PM
Sunday: Closed