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Basal Cell Carcinoma

bay-sahl sell kahr-si-no'mah

The most common eyelid tumor. It is caused by excessive exposure to sunlight. The tumor has a small crusty central crater and a hard rolled edge. It may grow large but rarely ever spreads to other parts of the body. In early stages, it is treated by surgery, radiation therapy, or freezing. Extensive plastic surgery or complete removal of the eye may be necessary.

Bell's Palsy
A temporary form of paralysis of the muscles on one side of the face due to nerve damage, but can interfere with blinking and protection of the eye.

BYE-foh kal

Bifocal lenses are simply two lenses with different focal points placed into one single pair of glasses.

Purpose of Bifocals:
The eye condition known as PRESBYOPIA is frequently responsible for needing bifocals as a lens treatment program. Essentially, as an individual ages, the natural elasticity of the lens inside the eye diminishes. As a result, the range in focus for the individual is shortened. For example, at the age of 16 the usual range of focus is from infinity up to 10 inches from the face. In contrast, at the age of 70 the range of focus may start at infinity, but stop at 40 inches. Much of our life requires vision closer than 40 inches, therefore, bifocal lenses offer an additional lens with a focal point that will allow clear vision, for that same individual, up to 16 inches.

While presbyopia is frequently responsible for bifocal lenses, there are many other conditions where the bifocal is the best treatment. Some of these are listed below:

  • Accommodative Insufficiency
  • Amblyopia (Lazy Eye)
  • Aphakia
  • Asthenopia (Eye Strain)
  • Convergence Insufficiency
  • Strabismus
  • Tracking Insufficiency

Types of Bifocals:
Bifocals are found in many different designs. The most common bifocal used today is found in glasses. It has the shape of the letter "D" laying on its side. These are available in a wide variety of sizes and powers. Other types of bifocals are round, or may be straight across the entire lens. A type of bifocal that has been gaining popularity for several years is the "Progressive" bifocal. Rather than having a distinct line between the two focal points of the lens, the progressive lens has a gradual transition from the top of the lens to the bottom. Doctors may choose this for their patients in an effort to give a broader range of focus as well as diminish the abrupt change when the eyes move up and down over the lens. Your doctor is trained to help you select the best design based on your individual needs. The patients employment activities, recreational needs and reading activities are all considered. While a bifocal for one activity may be perfect, for another it is completely useless. For example, the needs of a "golfer" may be significantly different than an "accountant". Other issues to consider may include the physical characteristics of the spectacle frames. For example, a frame that is vertically narrow may not allow enough room for a progressive lens to work well.

Bifocals & Contact Lenses:
Contact lenses also are available in bifocal designs. These come in the form similar to glasses in that there is a dividing line between the top of the contact lens and the bottom. Gas Permeable lenses frequently are in this format. The lens moves up and down on the cornea, depending on the eyelid configuration and the vertical angle of the eye. When this occurs, the lens is said to be "translating" properly. Another type of contact lens bifocal has concentric circles from the center of the lens. These circles alternate between distance vision and near vision. In this way, the eye is looking through two different focal points at the same time. These type lenses are most frequently available in soft lens designs, although some gas-permeable materials are available. Additionally, this type of bifocal lens is also available in Intraocular lens implants used at the time of cataract surgery (See: Pseudophakia). The appropriateness of any of these bifocal lens designs should be carefully discussed with your doctor.



Affecting or having to do with both sides of the body.

Binocular Vision

The ability to align both eyes on a visual point and combine the visual images seen by each eye into a single multidimensional image.

The muscles of the eye are used for alignment. The following image shows the muscles of the eye used for binocularity:

eye muscles

A person with poor binocularity may have some or all of the following symptoms: unstable vision, double vision, blurring, light sensitivity, headaches, dizziness, motion sickness, eye fatigue, poor depth perception, soreness or discomfort around eyes, poor hand-eye coordination, an inability to concentrate and a high level of distractibility.


When a trabeculectomy is performed to treat glaucoma, a small piece of the wall of the eye is removed and a "flap" is created to allow excess fluid to drain. This flap, created under the conjunctiva, forms a blister-like reservoir called a Bleb. A bleb usually has a tiny suture in it to keep the flap from healing shut. The fluid seeps out under the conjunctiva and is absorbed by the body.


Additional keywords and misspellings:
blebb trabeculotomy trabeculecomy glaucoma surgery high pressure



Blepharitis is an inflammation of the edge of the eyelids. There is a scaly dryness accompanied with redness and swelling of the lid margins. Blepharitis gives the appearance of "dandruff" on the lid margins, near the eyelashes. The lashes are often few in numbers and become irregular.

Cause Of Blepharitis:
Bacteria (usually Staphylococcus aureous) are found down in the eyelash follicle and secrete toxins which cause the eyelid to become inflamed. It is not contagious, in the usual sense; however, hand rubbing of the lid margins seems to increase the inflammation and swelling. It can be chronic. Long term chronic cases may result in lid deformities from years of scar tissue formation.

Types Of Blepharitis:
Two types of Blepharitis are common;

  • Seborrheic: This type is most often caused by meibomian gland dysfunction, in which an over-production of lipids creates the blockage. It can appear as mild redness and flaking or scaling around the eyelid and base of the eyelashes. The inner lining of the eyelid, the palpebral conjunctiva, may also appear rough and inflammed (a condition known as conjunctivitis). Because sebaceous gland dysfunction often accompanies this condition, dandruff of the scalp and other skin condtions involving acne may also be present. Hormones, nutrition, general physical condition and stress contribute to this form.
  • Staphylococcal This type is caused by staphylococcal bacteria usually beginning in childhood. Once the bacteria has been transmitted, it continues throughout adulthood. Common symptoms include dilated blood vessels, chalazions, loss of lashes, styes, and crusting or scaling around the eyes.
  • Treatment Of Blepharitis:
    The best treatment is to adopt a regimen of cleansing the lid margins. Scrubbing the lid margin with "baby shampoo" and then rinsing with hot water is best. There are commercially available lid shampoos that are available also. If this treatment does not stop or control the condition, then the individual should consult with an eye doctor. In more severe cases antibiotics are required to assist in the removal of the bacteria. Additionally, mild topically applied steroids may be required to reduce the inflammation caused from the toxins.

A relaxation of the skin of the eyelid.
The narrowing of the palpebral fissure; eye cannot be opened to normal extent.
A spasm of the obicularis oculi muscle resulting in forceful closer of the eyelids.
Blind Spot
The area where the optic nerve leaves the retina. A normal eye has a blind spot where there are no photoreceptor cells.
A bleb or blister; plural is bullae.

Buphthalmos is a congenital (inherited) form of glaucoma where the increased pressure is present at birth. High pressure in an eye of a child can also make the eye grow larger than normal. A child with bigger eyes usually becomes myopic and will need spectacle lenses to see clearly. Another known side effect is the tendency to develop a squint or lazy eye.

Who can get it?
Buphthalmos is inherited but is rare.

What are the symptoms?
Symptoms include abnormally large eyes, a haze on the clear portion of the eye (cornea), excessive tearing, photophobia (light sensitivity), and blindness.

An examination by an eye doctor may reveal increased intraocular pressure and cupping of the optic disk is not uncommon.

What is the treatment?
To save sight, surgical intervention is necessary. Procedures include a Goniotomy, Trabeculotomy, or Trabeculectomy to relieve excess pressure.

Additional keywords and misspellings:
bufthalmos infantile glaucoma enlarged eye

The Eye Encyclopedia is a collection of eye care terminology created by practicing optometrists and ophthalmologists. The information provided is not intended to be a substitute for regular medical care or to diagnose or treat any medical condition, and should be used only as a supplemental source of information. Please consult your doctor if you have any questions or concerns about your eye health.