Eye Care Blog

Good vision such as 20/20 does not mean satisfying contrast sensitivity. Common vision tests using black letters or numbers displayed against white backgrounds can not reflect your exact contrast sensitivity, since the real world is filled with grey shades. So that special contrast sensitivity testing is necessary.

May eye diseases or conditions may cause poor contrast sensitivity, such as cataracts, glaucoma, and diabetic retinopathy, as well as the side effects from LASIK and PRK. People with low contrast sensitivity may have difficulty in some conditions, such as seeing traffic lights, spot other cars and pedestrians during night driving. Since these people have poor perception of objects that do not stand out from their backgrounds, they may even stumble when they fail to see similarly colored pavements.

The term “contrast sensitivity function” (CSF) is used to describe people’s low contrast seeing ability. A contrast sensitivity test may be included in a routine screening after the visual acuity test, which measures the ability of seeing detailed letters or numbers. With your eyeglasses or contacts lenses wearing on, your eyes will be tested in together by a low-contrast test chart, which consists of bars and dots in different colored contrasts that are used to evaluate the patient’s exact CSF. Your CSF will certainly be affected by the sizes of objects: the larger the objects are, the higher CSF you can achieve.

By testing your eyes using bar and dot patterns displayed against varying contacts or intensities, your highest and lowest contrast sensitivity can be determined and plotted into a curve, which shows your contrast sensitivity readings. Tests under both bright and dark conditions can provide more detailed information about your images process capability.

As a volunteer, you can get a contrast sensitivity test as a necessary part of the evaluation of new ophthalmic devices such as LASIK excimer lasers and new intraocular lenses required by FDA. Once you are diagnosed with low contrast sensitivity, some remedies are available, depending on the source of the problem. Usually, artificial lenses with a yellow filter can improve contrast. If the low contrast sensitivity is caused by higher-order aberrations, wavefront lenses or LASIK are the right choices. Another option is intraocular lenses with yellow tints, which can also offset low contrast sensitivity.

Eyes are the windows of human’s hearts. It’s very important to have eye exams every year or six months, because many eye problems such as cataracts, retinal problems and glaucoma offer no telltale symptoms.

Routine eye exams mainly contain several steps. The first step of an eye exam is a measure of visual acuity. Eye doctors usually use a specially designed pocket eye exam card holding at about 14 inches before patient, or a standard eye exam wall chart with a distance of 20 feet. Each eye is tested independently while the other one is covered, to confirm the smallest characters patients can read. The letters at the last column of the eye exam card provide the patient’s acuity compared with normal subjects. For example 20/200 means the patient can see at 20feet when a normal one can see at 200 feet, what indicates that the patient’s vision is very lousy. The patient can also wear his glasses to finish the same eye exams, the result are called “best corrected vision”. The second step of an eye exam is pinhole testing to determine if the eye problem is a result of refractive error. Then the observation of external structures and testing extra-ocular movements are carried out for eye exams. After that, eye doctors will use the ophthalmoscope to do closer eye exam of the outer structures of the eye and view the retina and associated structures. If needed, the eye doctor will also measure the fluid pressure in the patient’s eyes. High pressure may be a symptom of glaucoma.

Besides routine eye exams, you may also visit your eye doctor for the information of eye fashion trends or choosing eyeglasses.

Two kinds of astigmatism are widely known: corneal astigmatism and lenticular astigmatism, both of which can be corrected by eyeglasses, contacts or refractive surgeries.  While the former type results from irregular shaped cornea, the latter type is caused by irregular lens shape.

Both adults and children can suffer from astigmatism. Common symptoms of astigmatism include blurry vision, headache, eye strain and distorted distance vision. Eye exams are critical to detect underlying astigmatism on children. The Ohio State University School of Optometry has ever found that 28% out of 2,523 children had astigmatism, which surely affected their school performance. What’s worse, most children are less self-aware about their vision problems,so ,they need regular eye exams.

Most of the astigmatism patients are born with that, which may get worse over time. Eye injuries, improper eye surgeries and keratoconus can also damage the corneal shape. The corneal shape of astigmatism patients is not perfectly spherical. Instead, it likes an oblong football, which causes light rays to focus on two points in the eye back. For regular astigmatism, its two meridians are located 90 degrees apart, so that it is easy to correct. However, irregular astigmatism has meridians that are other than 90 degrees apart, which brings more complexity for correction.

Prescriptions of eyeglasses or contact lenses for astigmatism correction usually have three parts. The first part is designed to provide common visual clarity. For example, convex lenses are used to correct hyperopia. A second part is particularly for astigmatism. And the third part is prescribed to bend certain light rays as a compensation for the cornea’s oval shape.

Nowadays, both rigid gas permeable contacts and soft toric lenses are available for astigmatism patients. Soft toric lenses can provide most comfort for most of people, while RGP contact are more competent for heavy astigmatism. If you can not get enough vision satisfaction from eyeglasses or contacts, refractive surgeries such as LASIK are the best choice.

Also called side vision, one people’s full horizontal and vertical vision range can be determined by a visual field test, which also detects potential blind spots in the visual field. Some eye and brain disorders are responsible for these visual field defects. Glaucoma, toxic exposure and retina damage can cause optic nerve damage and blind spots. Brain strokes and tumors may also affect the visual field.

A confrontation visual field testing can detect potential eye diseases and suggest for a further test. This test requires the patient to fixate on the doctor’s eye and describe the different numbers of fingers, which are within your peripheral viewing field but on the far edges.

Automated perimetry tests can evaluate your vision field by flashing random lights of different strength (generated by computer) in your peripheral vision field while your eyes are staring on a source light straight ahead. The patient uses a button to indicate the presence of objects. There may be a blind spot, if you fail to see objects in certain portion of the visual field.

Doubled contrasting colored (such as black and white) bars that are flickering at different frequencies are used to test the response of photoreceptors within the retina. Optic nerve damage or certain areas vision loss of the visual field can be detected if the patient fails to see bars at certain frequencies.

The fourth method will be like this: based on the anatomical relationship between the retinal images and the visual field, a device will be placed on your cornea to detect its electrical impulses, which are in turn used to detect your retina’s responses. This method is called electroretinogram. The patient’s cornea should be treated with a topical anesthetic to ease any discomfort.

Different people should receive complete eye exams at different intervals. Children’s eyes should be examined at six months of age, three years of age, and six or seven years of age and every two years during school days, since high vision problem rates are reported among both preschool and school-aged children. For children with risk factors of vision problems such as prematurity, developmental delays, turned eyes, family history of eye diseases and history of eye injury, more frequent eye exams are necessary.

Adults at different ages need eye exams in different frequencies. Based on American Optometric Association (AOA), among people less than 40 years old, one exam every two or three years is enough for those with normal vision, while an annual exam is required for those wearing eyeglasses or contacts. People with diabetes, high blood pressure and other disorders may also require more frequent eye exams. People above 40 need eye exams every one to two years and people over 60 need annual exams, in case of age-related problems such as presbyopia, cataracts and macular degeneration.

In the United States, ophthalmologists, optometrists, as well as opticians can conduct regular eye exams. Ophthalmologists are the most professional since they are exclusively licensed to perform eye surgeries. Optometrists can prescribe certain medications and minor surgical procedures, while opticians are only entitled to adjust and repair glasses, or fit your contacts.

A basic complete eye exam should contain several items: family eye history review, distance and near vision evaluation, current eye prescription determination, eye coordination evaluation and internal and external eye healthy examination. You should be clear of all these items as well as the exact charge at the time you make an appointment with your doctor. Exam fees for contact lens fitting, laser-surgery evaluation and pediatric testing are higher than that of regular exams. You should check your vision insurance benefits for potential discount, since exam fees vary widely from discount outlets to surgical offices.

For better exam results, you need to take necessary documents and cards of yourself and your family members. Your vision insurance card is needed if you want to get any discount. For your eyes full evaluation, your major medical health care cards and recent prescription glasses or contacts may be useful to provide additional eye exam aspects. A list of your prescription medications can help the doctor learn your complete health history. Of course, you can bring your interested questions.

article source:http://www.visioncarehome.com/

Regular comprehensive eye exams are crucial for both adults and children to maintain eye health. An eye exam can help adults not only formulate and update their eyewear prescription, but also search for any sign of common eye diseases. For children, eye exams are even more important since vision is so closely related to their study. If they have poor vision or image interpretation, they are most likely to have a poor performance in their study. Parents should take children to a related professional doctor for an eye examination as soon as they get a reading or learning difficulty, in order to find out the potential vision root.

Eyewear prescription is just a small portion of an eye exam. Its more significant role is to detect initial signs of eye diseases, preventing them from developing into more severe vision problems. The following two paragraphs is a description of some items for detection.

The first eye condition is refraction error, including myopia, hyperopic and astigmatism, all of which can be corrected using eyewear or refractive surgery. The second item that may be examined is amblyopia, which refers to the uneven development of the two eyes. Once found, amblyopia can be treated by covering the disabled eye, otherwise it will lead to permanent vision loss. A third search may be given to strabismus, which is also known as crossed or turned eyes in brief. People with this disease may have an unperfect eyes alignment, which may affect their depth perception and lead to amblyopia. Properly aligned eyes do not mean healthy eyes. So, the forth item may be teaming problems of the eyes. Signs of uncoordinated eyes (also named binocular vision problems) include headaches and eyestrain. An eye doctor should also pay attention to eye focusing problems during an eye exam. These problems may bother both children (resulted from incomplete focusing skills development) and aged people due natural decline, such as presbyopia.

Another part of examination items is related to more severe eye diseases. Early detection and subsequent treatment of eye diseases are essential to minimize the risk of lifelong vision impairment. Diabetic eye diseases are common and probably cause small blood vessel leaks or bleeding eye and macula swelling. Other eye diseases or health problems include glaucoma, high blood pressure, high cholesterol and so on. During eye exams, your doctor may check signs of these diseases using instruments or just by staring at your eye’s blood vessels and retina.

Vision screenings can never get the same effects from complete eye exams. A vision screening may test blur, muscle coordination and common eye diseases. These brief tests can only perform as an indicator for further eye exam, rather than replacing it. A driver’s license renewal just requires such a vision screening. Vision screenings can be conducted simply by school nurses, pediatricians, health care providers and volunteers. In contrast, a complete eye exam including all vision aspects testing must be carried out by an eye doctor, rather than incompetent family physicians and pediatricians. Only professional doctors can ensure all testing items and work out a proper personal treatment plan on the basis of the exam results.

If your doctor can not determine you eye problems, you may need to take a second exam after a period of time. For assured problems, a subsequent treatment plan will be made. Your eye doctor will prescribe different solutions for different eye problems. Corrective eyewear is commonly used for refractive errors. Binocular vision problems always require a vision therapy or strabismus surgery. For vision health maintenance or dry eyes relief, eye vitamins or vision nurture may be the right choice.

They came away with little more than pocket change, but the thieves who broke into Michelle Swainston’s car last June robbed of her of something even more precious.

They nabbed her eyeglasses.

“I couldn’t see,” recalled Swainston, who could not afford to replace them. Laid off from her job as an auto-parts inspector, she had recently learned she would not be called back to work.

With her income slashed by more than half, she and her husband had just enough left for the mortgage, car payment and necessities.

Then she learned an area eye practice was offering free eye exams to people hit hardest by tough economic times in Michigan.

She called Advanced Eyecare Professionals and signed up for one of its three annual Community Eyecare Days. An eye exam at the Hastings office revealed Swainston, 49, had glaucoma.

The practice provided corrective laser surgery and what Swainston called “the best pair of eyeglasses I’ve ever owned” at no charge.

“These people are so helpful,” she said. “If it wasn’t for them, I wouldn’t have glasses, and I probably would have lost my eyesight.”

Swainston is one of 300 people who have benefited from Community Eyecare Days. Advanced Eyecare Professionals sets aside three Saturdays per year to offer free eye exams and glasses, one day each at its offices in Hastings, Ionia and Lowell.

They are accepting patients for appointments at their next event, Oct. 10, in Lowell.

The eyecare days have been spearheaded by ophthalmic technician Joy Fountain, 25. Growing up poor meant she and her siblings had to be “very, very sick in order to see a doctor.” Her mother would put her own health issues on the back burner.

Fountain, a straight-A student at Godwin Heights High School, attended Grand Valley State University on a scholarship and says in touch with her mentor through the Big Brothers/Big Sisters program.

“This was kind of a personal thing for me,” Fountain said. “I received help through several organizations, and I (wanted) to give back.”

She has had the full backing of Dr. Michael Flohr, owner of the practice. Flohr has made four Lions International Mission Trips to Central America, providing medical care and cataract surgery to people there.

He said he wanted to help people close to home, as well.

“We have always felt we had a commitment to help people in our community,” he wrote in an e-mail. “And with the current economic situation, we felt there was an increased need for help.”

In 2008, the practice gave eye exams to 160 patients ranging in age from 2 to 81 at the community eyecare days.

Of those, 152 needed new glasses. Other medical diagnoses included glaucoma, cataracts, diabetes, retinopathy and macular degeneration.

So far this year, the practice has seen 40 patients at its Ionia community eyecare day and 64 in Hastings. Staff provided more than 100 pairs of glasses and more than $15,000 in services. Others who had recent prescriptions received glasses only.

The practice also offers information on state aid programs, such as Medicaid, and other health plans.

Flohr and other staff volunteer on the Saturdays eyecare clinics are scheduled.

Kelli Worth, who handles marketing and advertising for the practice, said they are happy to do it.

“It really means a lot to everybody who participates,” Worth said.

“They also receive a feeling of doing something for their fellow neighbor.”

Fountain recalls a woman who came in wearing her son’s taped-together glasses. Worse, his glasses were for a nearsighted person, and she was farsighted.

“She couldn’t believe she got new glasses,” Fountain said.

“One person who tells their story and says thanks and is in tears just makes the whole three months of planning worth it,” she added.

Fountain would like to see other practices — particularly dentists — adopt her idea.

“My hope is to take this a little bigger than Advanced Eyecare,” she said.

Worth agreed: “The impact could be huge. There is a lot of dental need out there,” she said.

Children always need basic visual skills for good learning, such as near vision, distance vision, binocular coordination, eye movement skills, focusing skills, peripheral skills and eye coordination. It is estimated that 5% of pre-schoolers and 25% of school-aged children suffer from various vision problems. The American Optometric Association recommends that children should receive comprehensive eye exams at six months of age, three years of age and six years of age. After they entering school, eye exams should be taken every two years for any vision problems and needs for eyewear. Early detection and treatment of vision problems are crucial for children.

Most of the children may receive their first eye exam from a family doctor or pediatrician. Once suspected problems are found, parents should take their children to professional ophthalmologist or optometrist for further examination with specific instruments. Items of children’s eye exams include vision testing, eyeglasses determination, eye alignment testing and probably, a parent education. Parents should fill in a case history form about their children after making an appointment with the doctor. The form may ask for children’s birth weight, full-term issue, pregnancy or delivery complications, current medications and present allergies. Parents should feel free to tell the doctor all of their children’s eye conditions, such as frequent eye rubbing, excessive blinks, eye contact failure, poor eye tracking skills, as well as previous ocular diagnosis and treatments, family eye problems history etc…

Infants at three or four months old should receive several eye tests to assess whether they have developed required focusing skills, color vision and depth perception. Pupil response tests can show that whether the children’s eye pupil opens and closes properly in the presence or absence of light. Children may also be tested that whether they can focus and follow moving objectives. Blank and stripe cards can be used to evaluate infants’ preferential looking skills.

Eye tests for pre-school children involve some non-verbal symbols. The first type is LEA symbols, including apples, houses, squares and circles. Retinoscopy is used to test the eye’s response to light, and random dot stereopis is used to test the two eyes’ relation. The assessment of amblyopia for children requires some skills since there is no detectable anatomic damage. Amblyopia can be corrected using eye patching, which may strengthen the weaker eye. Also called strabismus, misalignment eyes may be caused by disabled muscle control in the affected eye or eyes. Some other testing items including correct focusing, depth perception, distance gauge ability and color vision are also important. Furthermore, children’s eyelids and lid margins may be examined to find potential abnormal eyelash follicles, bumps, discharge and swelling. And cornea, iris and lens examinations may discover cloudiness or other irregularities.

Eye problems on children such as lazy eye must be detected and treated as early as possible, since good vision is critical for school performance.