FAQ on EyE CARE

Why Does My Eye Twitch?

Mild twitching of the eyelid is a common phenomenon. Although these involuntary contractions of muscles are annoying, they are almost always temporary and completely harmless. The medical name for this kind of twitching is ocular myokymia. It is quite common and most often associated with fatigue. When your eye is twitching, it is not visible to anyone else. Ophthalmologists often are asked what causes the twitching and what can be done to stop it. Lack of sleep, too much caffeine or increased stress seem to be root causes. Often, gently massaging your eye will relieve the symptoms. Usually, the twitch will disappear after catching up on your sleep.

Back to Top

General Vision

What is the difference between an ophthalmologist, an optometrist and an optician?

* An Ophthalmologist (MD) has a medical degree and is licensed to practice medicine and perform eye surgery.
* An ophthalmologist has had at least 12 years of education and training beyond high school and is qualified to diagnose and treat all eye diseases; perform surgery; prescribe and fit glasses and contact lenses.
* An Optometrist (OD) has a degree in optometry and is licensed to practice optometry. An optometrist has had at least six years of education and training beyond high school and is qualified to determine the need for glasses and contact lenses; prescribe optical correction; and screen for some eye conditions.
* An Optician usually has a combination of college (or two years of opticianry school) and on-the-job training. An optician is trained to fit and dispense eyeglasses or contact lenses based upon a prescription from a licensed ophthalmologist or optometrist.

How does normal vision develop?

Newborn infants are able to see, but as they use their eyes during the first months of life, vision improves. During early childhood years, the visual system changes quickly and vision continues to develop. If a child cannot use his or her eyes normally, vision does not develop properly and may even decrease. After the first nine years of life, the visual system is usually fully developed and usually cannot be changed.

The development of equal vision in both eyes is necessary for normal vision. Many occupations are not open to people who have good vision in one eye only. If the vision in one eye should be lost later in life from an accident or illness, it is essential that the other eye have normal vision. Without normal vision in at least one eye, a person is visually impaired.

How does the eye work?

When you take a picture, the lens in the front of the camera allows light through and focuses that light on the film that covers the back inside wall of the camera. When the light hits the film, a picture is taken. The eye works in much the same way. The front parts of the eye (the cornea, pupil and lens) are clear and allow light to pass through. The light also passes through the large space in the center of the eye called the vitreous cavity. The vitreous cavity is filled with a clear, jelly-like substance called the vitreous or vitreous gel. The light is focused by the cornea and the lens onto a thin layer of tissue called the retina, which covers the back inside wall of the eye. The retina is like the film in a camera. It is the seeing tissue of the eye. When the focused light hits the retina, a picture is taken. Messages about this picture are sent to the brain through the optic nerve. This is how we see.

Further information on this topic, visit anatomy of the eye.

Back to Top

Eye Examinations

When should my child's eyes be examined?

Most physicians test vision as part of a child's medical examination. They may refer a child to an ophthalmologist (a medical eye doctor) if there is any sign of an eye condition. The American Academy of Ophthalmology and the American Academy of Pediatrics recommend the first vision screening occur in the hospital as part of a newborn baby's discharge examination. Visual function (including ocular alignment, etc.) also should be checked by the pediatrician or family physician during routine well-child exams (typically at two, four and six months of age). Later amblyopia and alignment screenings should take place at three years of age and then yearly after school age.

If you suspect your child suffers from decreased vision - amblyopia (poor vision in an otherwise normal appearing eye), refractive error (nearsightedness or farsightedness) or strabismus (misalignment of the eye in any direction) - or if there are hereditary factors that might predispose your child to eye disease, please make an appointment with an ophthalmologist as soon as possible. New techniques make it possible to test vision in infants and young children. If there is a family history of misaligned eyes, childhood cataracts or a serious eye disease, an ophthalmologist can begin checking your child's vision at a very early age.

When should an adult's eyes be examined?

Adult examinations of the eyes should be performed on a regular basis.
o Young adults (ages 20 - 39) should have their eyes examined every three-five years.
o Adults ages (ages 40 - 64) should have their eyes examined every two-four years.
o Seniors (over 65 years of age) should have their eyes examined every one-two years.
High risk adults include:
o People with diabetes
o People with glaucoma or strong family history of glaucoma
o People with AIDS/HIV

For more information about this topic, visit eye exams

Back to Top

Visual Acuity, Vision Impairments and Low Vision

What are the medical terms for nearsightedness and farsightedness?

* The medical term for nearsightedness is myopia, correctable with glasses, contact lenses or, in some cases, refractive surgery (LASIK or Corneal Ring Implants).
* The medical term for farsightedness is hyperopia, correctable with glasses, contact lenses or, in some cases, refractive surgery.
* Related conditions (also correctable with glasses or contact lenses) include astigmatism and presbyopia.

What is visual acuity?

Acuity is the measure of the eye's ability to distinguish the smallest identifiable letter or symbol, its details and shape, usually at a distance of 20 feet. This measurement is usually given in a fraction. The top number refers to the testing distance measured in feet and the bottom number is the distance from which a normal eye should see the letter or shape. So, perfect vision is 20/20. If your vision is 20/60, that means what you can see at a distance of 20 feet, someone with perfect vision can see at a distance of 60 feet.

What is legal blindness?

You are legally blind when the best corrected central acuity is less than 20/200 (perfect visual acuity is 20/20) in your better eye, or your side vision is narrowed to 20 degrees or less in your better eye. Even if you are legally blind, you may still have some useful vision. If you are legally blind, you may qualify for certain government benefits.

What is visual impairment?

If neither of your eyes can see better than 20/60 without improvement from glasses or contacts, you may be defined as visually impaired. In addition, poor night vision, limited side vision, double vision and loss of vision in one eye may also determine visual impairment.

What is low vision?

Low vision is a term describing a level of vision below normal (20/70 or worse) that cannot be corrected with conventional glasses. Low vision is not the same as blindness. People with low vision can use their sight. However, low vision may interfere with the performance of daily activities, such as reading or driving.

Can eyes be transplanted?

No. Currently, there is no way to transplant a whole eye. However, corneas have been successfully transplanted for many years.

Back to Top

Genetic Research

What is human genetic research?

The basis for many, if not most, diseases can be found in our genes. Genes and their protein products determine how we look and develop, how efficiently we process foods, how effectively we detoxify poisons and how vigorously we respond to infections. It is thought that more than 4,000 diseases arise from changed or mutated genes that are inherited from one's mother and/or father. Common disorders such as age-related macular degeneration, diabetes, heart disease and most cancers arise from a complex communication between multiple genes and between genes and factors in our environment. Genetic research studies are aimed at identifying these genes and understanding how changes in these genes lead to disease.

The benefits of human genetic research include medical breakthroughs made possible because of the combined commitment of participants and researchers. Identifying a gene opens many new diagnostic and treatment possibilities including earlier diagnosis of inherited eye diseases. Researchers also work to determine exactly what causes a particular eye disease and why the same disease does not effect everyone in the same way. As a result, researchers hope to develop improved treatment for specific eye diseases such as glaucoma and inherited retinal diseases including AMD. These discoveries will lead to improved eye care for future patients.

What is genetic testing?

Genetic tests, also called DNA-based tests, are some of the newest and most sophisticated techniques that we can use to test for genetic diseases. Most tests involve looking directly at the DNA in a specific disease-associated gene. The actual information of each gene is carried within the DNA itself. The DNA can be taken from cells in a sample of blood or, occasionally, from other body fluids or tissues.

The UM Kellogg Eye Center offers state-of-the-art genetic testing services through its Ophthalmic Molecular Diagnostic Laboratory. Testing allows ophthalmologists to confirm diagnoses and help patients understand their risks for certain inherited eye diseases. Kellogg is unique in its ability to offer this genetic testing service, which also provides patients with an exceptional genetic counseling program.

Are genetic study participants all patients at Kellogg?

Not necessarily. Enrollment involves donating a blood sample one time only and providing medical and family history information. This can all be done long distance. There is no cost to the participant.

What is genetic counseling?

Genetic counseling is a communication process which deals with the human problems associated with the occurrence, or the risk of occurrence, of a genetic disorder or birth defect in a family. As part of this process, the patient obtains information regarding diagnosis, treatment, prognosis and inheritance of the genetic condition or birth defect of concern to the family. In some cases genetic testing is available for specific genetic diseases.

Back to Top
Contact Lenses

Can my child wear contact lenses during sports activities?

Yes, contact lenses provide excellent vision for most sports. However, they do not protect the eyes from injury. Therefore, contact lens wearers should use polycarbonate sports safety goggles or glasses when participating in sports. Also see information about preventing eye injuries.

Do contact lenses prevent nearsightedness (myopia) from getting worse?

No, there is no evidence that wearing contact lenses improves vision or prevents myopia from getting worse. Also see information about contact lenses.

Can I use my eyeglass prescription to buy over-the-counter contact lenses?

No, because it does not provide the specifications for lens diameter, thickness and base curve. A new prescription must be carefully fitted by an eye care specialist to avoid serious adverse reactions.

Is it safe for me to clean my contact lenses with a homemade solution?

Using commercial saline solutions is the safest method of cleaning lenses. Some studies have shown that homemade solutions may lead to corneal infections. Also see information about contact lenses.

Back to Top

Computers, TVs, Lighting and Glasses

Will working at a computer screen hurt my eyes?

No, there is no evidence that working at a computer damages the eyes. However, long hours of work can be fatiguing to the eyes, neck and back. Monitor glare from various light sources can also be a problem. It is often helpful to take periodic breaks, looking off in the distance and adjusting your work station (angle of the monitor, height of the chair, changing the lighting, etc.).

Is pink-eye contagious?

Yes, viral conjunctivitis (pink-eye) is very common and is extremely contagious. Avoid touching eyes with your hands, wash hands frequently, do not share towels, and avoid work, school or daycare activities for a least five days or as long as discharge is present.

Will sitting too close to the television set hurt my child's eyes?

No, there is no scientific evidence that TV sets emit rays that are harmful to the eyes.

Why have I gradually found it harder to read without glasses?

The ability to focus on near objects decreases steadily with age and is referred to as presbyopia. Presbyopia is a natural aging of the lens. It is usually near the age of 40, when glasses or bifocals are prescribed to correct this condition.

Are sunglasses good for my eyes?

There is a benefit to wearing UV protective lenses--wearing them may protect against cataract formation. Clear lenses with UV protection may offer greater protection than dark lenses because they allow the eyes to be exposed to more light. This causes greater constriction of the pupil which lets less light enter the eyes.

Is my child likely to inherit my need for glasses?

Possibly. If both the biological parents wear glasses, your children are likely to need them as well.

Will reading in dim light hurt my eyes?

No, but most people are more comfortable reading with proper lighting which is bright enough to provide good illumination but not so bright as to cause glare.

How often do I need to get my prescription changed?

There is no predetermined schedule for changing glasses or contacts. It is necessary to change your prescription only when it no longer provide adequate correction. However, it is still a good idea to have regular eye examinations.

What materials are available for glasses?

Some of the newest materials for frames include titanium (virtually indestructible) and polycarbonate materials (recommended for high impact sports). Lenses are also made from polycarbonate materials, other types of light weight plastics and glass. Coatings include UV protection (recommended for all types of lenses), scratch-resistant protection, polarization, anti-glare and others. See the Kellogg Optical Shop for more information about glasses.





-1.1: What is Myopia ?
Myopia is often referred to as short-sightedness or near-sighted. ...

-1.2 What is Hyperopia ?
Hyperopia is often referred to as long-sightedness or far-sighted....

-1.3 What is Emmetropia ?
Emmetropia is just another name for an eye that has no optical defects and ...

-1.4 What is Astigmatism ?
An astigmatic eye generally has two different meridians, at 90degrees to ...

-1.5 What is Presbyopia ?
Presbyopia describes the condition whereby the amplitude of accommodation, ...

-1.6 How is Visual Acuity Measured
Visual acuity is the measure of the sensitivity of the visual system. ...

-2.0 Terminology of Spectacles
Lenses commonly used for spectacles are either spherical powered ...

-2.1 How to read a glasses prescription
A prescription for spectacles will generally contain the powers for lenses ...

-2.2 Why the difference between the way Optometrists and Ophthalmologists write the prescription ?
There are two ways of writing the prescription; referred to as plus-cyl ...

-2.3 How to convert between the two forms
To convert from plus-cyl form to minus-cyl form use the following steps:...

-2.4 Eyeglass Lens materials
Spectacle lenses are made of two main types of materials - plastic or glass....

-2.5 Types of Spectacle Lenses
+ Single Vision ...

-2.6 Ultra Violet absorption and Lenses
Spectacle lenses, depending on the type of material will absorb varying ...

-2.7 Standards Requirements for Spectacle Lenses
International and local standards define the properties of lenses that ...

-2.8 Cost of frames
Varies depending on the type of material, eg plastic frame to titanium metal....

-2.9 Cost of lenses
Like frames varies with the type of the material. Also depends if the ...

-2.10 Reducing the edge thickness of the lens
Since edge thickness is a function of lens power, centre thickness ...

-2.11 Internet Ordering of Prescriptions and Sunglasses
The are a wide variety of companies that advertise on the internet ...

-3.0 WWW Sites on Contact Lenses
URL: http: //www.sna.com/etonline/...

-3.1 Difference between soft and hard contact lenses
Soft lenses are manufactured from a plastic hydrogel polymer, ...

-3.2 How to Read a Contact Lens Description:

-3.2 Types of Soft Contact Lenses
Soft contact lenses vary depending on either the refractive correction that ...

-3.2.1 Spherical
Single prescription power 360 degrees around the lens....

-3.2.2 Toric
Contains both a spherical and cylinder component to correct prescriptions ...

-3.2.3 Disposable
Spherical or toric contact lenses which are designed to be worn for a ...

-3.2.4 Extended Wear
Lens manufactured from a high-water content material and/or with a very ...

-3.2.5 Bifocal Lenses
There are a variety of designs in bifocals, essentially all ...

-3.3 Types of Rigid Contact Lenses
Rigid contact lenses also vary depending on the material and the design of ...

-3.3.1 PMMA
Original material used in the construction of hard contact lenses....

-3.3.2 RGP
Combination of PMMA and other polymers to increase the oxygen permeability ...

-3.3.3 Spherical
same as for soft contact ...

-3.3.4 Toric
Can be either toric periphery, which is used for fitting reasons, ...

-3.3.5 Bifocal
The different types include;...

-3.4 Costs of Contact Lenses
Varies depending on the type of contact ...

-3.5 Solutions required for CL maintenance
In general all contact lenses, whether soft of rigid type, will ...

-3.6.1 Why do I have to clean my Contact Lenses ?
Cleaning removes surface debris and bacteria that may adhere to the ...

-3.6.2 Why is there a limit to the length of wearing time ?
The cornea the clear part of the eye, is avascular or without a blood supply....

-3.6.3 Can I lose the lens behind my eye ?
Short answer is no. The conjunctiva, the tissue that covers the white ...

-3.6.4 How do I tell if I've lost the lens from my eye?
Cover the other eye to determine if vision is still clear from the eye where ...

-3.6.5 How can I tell if I've put them in the wrong eye ?
Check the vision of each eye by covering alternate eyes with your hand....

-3.6.6 How to tell if the lenses are inside out ?
Soft lenses will appear as a smooth dish shape when placed on the end of ...

-3.6.7 How do I know when to dispose of my disposable lenses ?
The lenses will not automatically self-destruct at the end of the wearing ...

-3.6.8 Can I store my lenses in tap water ?
Short answer - No !. There are a number of nasty micro- organisms,...

-3.6.9 Can I store my lenses dry ?
Soft lenses - definitely not !. Soft lenses stored dry will turn into ...

-3.6.10 How long does it take to adapt to new lenses ?
Soft lenses are generally worn for 2-4hrs on the first day and the wearing ...

-3.6.11 Why do I have to use protein cleaner ?
Contact lenses are exposed to a complex environment whilst on the eye. ...

-3.6.12 Can I use eyedrops with my contact lenses ?
In general eyedrops shouldn't be used with contact lenses because the lens ...

-3.6.13 How do I get around dryness with contact lenses ?
Try using an in-eye lubricant. There can be some dryness if you work in ...

-3.7 Risks and Benefits of Contact Lenses

-3.8 Mail order contact lenses
Easiest method to locate the contact lens suppliers on the internet ...

-3.9 Making your own saline - risks
Greatest risk in manufacturing your own saline is the acanthamoeba. ...

-4.1 Introduction
This section, and the subsequent section, are only an overview of some ...

-4.2 Conjunctivitis
Conjunctivitis is an inflammation of a mucous membrane and therefore in ...

-4.3 Dry Eyes
- Causes [Details to be added ]...

-4.4 Eyelid Problems
Styes are common eyelid problems and are a type of boil involving an ...

-4.5 Keratoconus
Keratoconus (conical cornea) is an recessive inherited condition usually ...

-4.6 Herpes Zoster ("Shingles")
Affects the eye by encroaching from a skin lesion or starts ...

-4.7.1 General Effects of Radiation on the eye
UV radiation is classified ...

-4.7.2 Visual Displays and Radiation

-4.8 Iridology
This is postulated as a means of determining general health by ...

-5.1 Floaters and Spots in the Field of View
Floaters (muscae volitantes - flying flies) are spots before the eyes ...

-5.2 Macular Degeneration
The macular is the innermost part of the central retina; an area where ...

-5.3 Retinal Detachments
The retina is one of the three layers of the human eye. The innermost ...

-5.4 Diabetes and The Retina
Diabetes causes a number of retinal changes which can include haemorrhages,...

-5.5 Retinitis Pigmentosa
Retinitis Pigmentosa is a degeneration of the retinal pigment epithelium....

-5.6 Glaucoma
Glaucoma is a symptomatic condition and not a disease sui generis. It ...

-5.7 Cataracts
Cataracts are opacifications of the crystalline lens of the eye, causing ...

-5.8 Uveitis:
[ TBD - details to be added ]...

-5.9 Ocular Migraines:

-5.9.1 Introduction:
The following is an attempt to give an_introduction_only to this vast ...

-5.9.2 Classification of migraine:
I. Common migraine. The comprises about 80% of those with migraines. It is ...

-5.10 Chorioditis:
Choroiditis is an inflammation of the choroid, the second coat of ...

-6.1 Strabismus (Turned Eye)
A squint or strabismus is a failure of the two eyes to look at the same ...

-6.2 Amblyopia ("Lazy Eye")
Amblyopia is defined by Schapero et al. as the condition of reduced ...

-6.3 Problem(s) When Wearing Glasses
- Reflections....

-6.4.1 Vision Therapy Introduction
Common problems that require vision therapy ...

-6.4.2 Vision Therapy: Bates Method
Vision therapy, especially people claiming improvement of vision ...

-7.1 Defective Colour Vision:
Defects in colour vision, often incorrectly referred to as colour ...

-7.2 Classification of Congenital Colour Vision Defects

-7.3 Classification of Acquired Colour Vision Defects

-7.4 WWW Resources on Colour

-8.0 WWW Resources on Refractive Surgery:
URL: http://www.eyenet.org/public/faq/refractive_surgery_faq....

-8.1 Types of Refractive Surgery
There are basically 4 main operations performed for correction of ...

-8.2 Description of the Procedures:

-8.2.1 Suitability for each procedure

-8.3 Comparison of RK, PRK and ALK and LASIK:
PRK: involves less than 5% the depth of the cornea, typically. ...

-8.4 Complications of the Procedures
PRK Side Effects -...

-8.6 Criteria for Suitability of Procedures
PRK: The following guidelines are suggested for those individuals suitable ...

-8.7 Personal Experiences of Refractive Surgery
The following information details the personal experiences that some ...

-8.7 Personal Experiences of Refractive Surgery #2
The following information is details of experiences of patients ...

-8.7 Personal Experiences of Refractive Surgery #3
The following information was kindly contributed by Dr Robert Maloney M....

-8.7 Personal Experiences of Refractive Surgery #4
ALK:

-8.7 Costs of Surgery:

-8.8 Further information on Procedures:
The supplement to volume 9 No. 2 (March - April 1993) of the Journal ...

-8.9 Location of Places Performing Surgery
URL: http://www-or.stanford.edu/~mob/...

-8.10 OrthoKeratology
Fitting RGP contact lenses to change shape of cornea....

-10.0 Internet Vision/Health Resources
A large number of resources specific for ophthalmology/optometry ...

-10.1 Guide to On-Line Medical Resources
An extensive list of Internet Medical resources are listed in the ...

-10.2 Images of Eye Conditions/Diseases
Images of retinal and eye conditions as GIF/TIFF files ...

-11.0 Mailing Lists
A number of mailing lists are located on the Internet which deal with ...

-11.1 RPList

-11.2 CVNet
This list deals with colour and vision research. ...

-11.3 ColorCat
This list deals with Color ...

-11.4 HMatrix
[ Details to be added ]...

-11.5 BlindFam
This list is for the discussion of all aspects of family life as affected ...

-11.6 BlindNews
This list deals with issues of the visually handicapped. ...

-11.7 MedNet
[ Details to be added ]...

-11.8 EyeMove
This list is for scientists and clinicians interested in all aspects of ...

-11.9 LiveEye
This list also deals with colour and vision research. ...

-11.9a National Marfan Foundation

-11.10 PupilNet
From the announcement page......

-11.11 Sjogren's Syndrome List (SS-List)
This list is for the discussion of sjogren's syndrome....

-11.12 Ophthalmic Photography and Imaging Mailing List (OPTIMAL)
This list is for the discussion of ophthalmic photography ...

-11.13 Ophthalmogenetics Mail List
This list is for the discussion of Ophthalmogenetics (genetics ...

-11.14 Myopia Research mailing List:

-12.0 World Wide Web (WWW)
Other related Web servers include :...

-13.0 Email for Optoms/Ophthals & Net Resources
Currently the national board for USA is on the internet ...

-13.1 Commercial Interests on the Net: