Sergeant Bluff Eye Care

Eye Health

By

Finding the Right Contact Lenses

Contact lenses are a great alternative to wearing eyeglasses. An often unknown fact is that not all patients wear contact lenses as their primary source of vision correction. Each patient is different, with some patients wearing contact lenses only on weekends, special occasions or just for sports. That is the beauty of contact lens wear, the flexibility it gives each individual patient and their lifestyle.

If you decide to opt for contact lens wear, it is very important that the lenses fit properly and comfortably and that you understand contact lens safety and hygiene. A contact lens exam will include both a comprehensive eye exam to check your overall eye health, your general vision prescription and then a contact lens consultation and measurement to determine the proper lens fit.

Whether or not you have vision problems, it is important to have your eyes checked regularly to ensure they are healthy and that there are no signs of a developing eye condition. A comprehensive eye exam will check the general health of your eyes as well as the quality of your vision. During this exam the eye doctor will determine your prescription for eyeglasses, however this prescription alone is not sufficient for contact lenses. The doctor may also check for any eye health issues that could interfere with the comfort and success of contact lens wear.

The Contact Lens Consultation

The contact lens industry is always developing new innovations to make contacts more comfortable, convenient and accessible. Therefore, one of the initial steps in a contact lens consultation is to discuss with your eye doctor some lifestyle and health considerations that could impact the type of contacts that suit you best.

Some of the options to consider are whether you would prefer daily disposables or monthly disposable lenses, as well as soft versus rigid gas permeable (GP) lenses. If you have any particular eye conditions, such as astigmatism or dry eye syndrome, your eye doctor might have specific recommendations for the right type or brand for your optimal comfort and vision needs.

Now is the time to tell your eye doctor if you would like to consider colored contact lenses as well. If you are over 40 and experience problems seeing small print, for which you need bifocals to see close objects, your eye doctor may recommend multifocal lenses or a combination of multifocal and monovision lenses to correct your unique vision needs.

Contact Lens Fitting

One size does not fit all when it comes to contact lenses. Your eye doctor will need to take some measurements to properly fit your contact lenses. Contact lenses that do not fit properly could cause discomfort, blurry vision or even damage the eye. Here are some of the measurements your eye doctor will take for a contact lens fitting:

Corneal Curvature

In order to assure that the fitting curve of the lens properly fits the curve of your eye, your doctor will measure the curvature of the cornea or front surface of the eye. The curvature is measured with an instrument called a keratometer to determine the appropriate curve for your contact lenses. If you have astigmatism, the curvature of your cornea is not perfectly round and therefore a “toric” lens, which is designed specifically for an eye with astigmatism, would be fit to provide the best vision and lens fit. In certain cases your eye doctor may decide to measure your cornea in greater detail with a mapping of the corneal surface called corneal topography.

Pupil or Iris Size

Your eye doctor may measure the size of your pupil or your iris (the colored area of your eye) with an instrument called a biomicroscope or slit lamp or manually with a ruler or card. This measurement is especially important if you are considering specialized lenses such as Gas Permeable (GP) contacts.

Tear Film Evaluation

One of the most common problems affecting contact lens wear is dry eyes. If the lenses are not kept adequately hydrated and moist, they will become uncomfortable and your eyes will feel dry, irritated and itchy. Particularly if you have dry eye syndrome, your doctor will want to make sure that you have a sufficient tear film to keep the lenses moist and comfortable, otherwise, contact lenses may not be a suitable vision option.

A tear film evaluation is performed by the doctor by putting a drop of liquid dye on your eye and then viewing your tears with a slit lamp or by placing a special strip of paper under the lid to absorb the tears to see how much moisture is produced. If your tear film is weak, your eye doctor may recommend certain types of contact lenses that are more successful in maintaining moisture.

Contact Lens Trial and Prescription

After deciding which pair of lenses could work best with your eyes, the eye doctor may have you try on a pair of lenses to confirm the fit and comfort before finalizing and ordering your lenses. The doctor or assistant would insert the lenses and keep them in for 15-20 minutes before the doctor exams the fit, movement and tearing in your eye. If after the fitting, the lenses appear to be a good fit, your eye doctor will order the lenses for you. Your eye doctor will also provide care and hygiene instructions including how to insert and remove your lenses, how long to wear them and how to store them if relevant.

Follow-up

Your eye doctor may request that you schedule a follow-up appointment to check that your contact lenses are fitting properly and that your eyes are adjusting properly. If you are experiencing discomfort or dryness in your eyes you should visit your eye doctor as soon as possible. Your eye doctor may decide to try a different lens, a different contact lens disinfecting solution or to try an adjustment in your wearing schedule.

If you would like to switch from glasses to contacts, please give our office a call to set up your appointment!

By

How Does the Eye Work?

To understand how the human eye works, first imagine a photographic camera—since cameras were developed very much with the human eye in mind.

How do we see what we see?

Light reflects off of objects and enters the eyeball through a transparent layer of tissue at the front of the eye called the cornea. The cornea accepts widely divergent light rays and bends them through the pupil—the dark opening in the center of the colored portion of the eye.

The pupil appears to expand or contract automatically based on the intensity of the light entering the eye. In truth, this action is controlled by the iris—a ring of muscles within the colored portion of the eye that adjusts the pupil opening based on the intensity of light. (So when a pupil appears to expand or contract, it is actually the iris doing its job.)

The adjusted light passes through the lens of the eye. Located behind the pupil, the lens automatically adjusts the path of the light and brings it into sharp focus onto the receiving area at back of the eye—the retina.

An amazing membrane full of photoreceptors (a.k.a. the “rods and cones”), the retina converts the light rays into electrical impulses. These then travel through the optic nerve at the back of the eye to the brain, where an image is finally perceived.

The main parts of the human eye include:

  • Cornea: transparent tissue covering the front of the eye that lets light travel through
  • Iris: a ring of muscles in the colored part of the eye that controls the size of the pupil
  • Pupil: an opening in the center of the iris that changes size to control how much light is entering the eye.
  • Sclera: the white part of the eye that is composed of fibrous tissue that protects the inner workings of the eye
  • Lens: located directly behind the pupil, it focuses light rays onto the retina
  • Retina: membrane at the back of the eye that changes light into nerve signals
  • Rods and cones: special cells used by the retina to process light
  • Fovea: a tiny spot in the center of the retina that contains only cone cells. It allows us to see things sharply.
  • Optic Nerve: a bundle of nerve fibers that carries messages from the eyes to the brain
  • Macula: a small and highly sensitive part of the retina responsible for central vision, which allows a person to see shapes, colors, and details clearly and sharply.

A delicate system, subject to flaws.

It’s easy to see that a slight alteration in any aspect of how the human eye works—the shape of the eyeball, the cornea’s health, lens shape and curvature, retina problems—can cause the eye to produce fuzzy or blurred vision. That is why many people need vision correction. Eyeglasses and contact lenses help the light focus images correctly on the retina and allow people to see clearly.

In effect, a lens is put in front of the eye to make up for any deficiencies in the complex vision process.

If you’d like more information about how the eye works and want a comprehensive exam to make sure your vision is top-notch, please contact us today!

By

What are Refractive Errors?

Have you ever heard of a refractive error? Refractive errors are not eye diseases; it is a result of and imperfection of the size and shape of the eye, which results in blurry or double vision. Here are some of the most common refractive errors:

Astigmatism

Many people have never heard of astigmatism, although it is an extremely common eye condition.

If left untreated, astigmatism may cause eyestrain, headaches, and blurry vision. If you have astigmatism you may not see objects in the distance or near without some form of distortion.

Symptoms of Astigmatism

Small amounts of astigmatism can go unnoticed, however, you may be suffering from eye fatigue, eyestrain, and headaches.

Astigmatism is a condition that usually can develops early in childhood. According to a study from The Ohio State University School of Optometry, 28% of school age children suffer from astigmatism. Parents should be aware that their children might not notice that their vision is blurry, not understanding that this is not normal. Nevertheless, astigmatism should be treated because vision problems can lead to learning problems and in extracurricular activities. Make sure to have your child’s eyes examined at an eye doctor’s office at least once a year.

Causes of Astigmatism

Astigmatism is generally caused by a cornea with an irregular shape. The cornea is the front, clear layer of the eye. With astigmatism, the cornea is not round and spherical and is instead irregular having two curves instead of one curve. Astigmatism in some cases could also be caused by the lens located inside the eye that is irregular in shape.

Eyes with astigmatism distort the light that comes into the eyes because the cornea is irregularly shaped. This causes the light rays entering the eye to create two images in the back of the eye (because of the two curves), instead of one image. This is what causes the distortion in sight.

Treatments for Astigmatism

For most people, their astigmatism is fully corrected using prescription glasses or contact lenses. If you select contact lenses to correct your vision, soft contact lenses are the most common option. If for whatever reason soft contact lenses are not an option, rigid gas permeable (RGP or GP) are also a great choice. Rigid gas permeable lenses usually give the clearest vision but the adaptation process will be significantly longer. Another option are hybrid contact lenses. These contacts have a center made from a rigid gas permeable (RGP) lens and an outer ring made of soft contact lens material. This type of lens provides both excellent clarity and comfort. LASIK could be another option to correct astigmatism. LASIK usually only corrects low levels of astigmatism and some patients with higher levels of astigmatism might not be candidates.

Myopia

Nearsightedness, otherwise known as Myopia, is one of the most common vision problems.

Myopia, has increased by 66 percent since 1970-1971 according to a National Eye Institute (NEI) study that compared rates of myopia in the USA with a survey conducted 1994-2004. The rate of myopia rose from 25 percent of participants to 41.6 percent.

Nearsighted people have difficulty reading signs and clearly seeing distant objects, but they can see up-close tasks such as reading or sewing, just fine.

Myopia Signs and Symptoms

Nearsighted people report headaches or eyestrain more often, and they squint or feel fatigued while driving or during sports. If the symptoms persist while wearing glasses or contact lenses, the corrective prescription may need adjustment.

What Causes Myopia?

Myopia occurs when the eyeball is slightly misshapen, longer than usual, from front to back. This causes light rays to focus at a point in front of the retina, rather than directly on the surface.

Nearsightedness runs in families and usually begins during childhood. This vision problem may stabilize at a certain point, although it also may worsen with age.

Myopia Treatment

Nearsightedness is mostly corrected with glasses, contact lenses or refractive surgery. Depending on the degree of myopia, you may need eyeglasses or lenses all the time, or only when sharper distance vision, like driving, or viewing a chalkboard, movie etc., is desired.

If your glasses or contact lens prescription begins with a minus number, e.g: -2.00, you are nearsighted.

Refractive surgery is a more “permanent” option for correcting myopia. This includes laser procedures such as LASIK and PRK, or non-laser options such as corneal inserts and implantable lenses. One advantage of the non-laser options is that, although they’re intended to be permanent, they may be removed in case of a problem or change of prescription.

Orthokeratology is a non-surgical procedure where special rigid gas permeable (GP) contact lenses are used to slowly reshape the cornea during sleep. After the lenses are removed the cornea retains the new shape. The patient can see clearly during the day without wearing glasses or contact lenses.

 

Hyperopia

Hyperopia -Farsightedness, is a common vision problem affecting about 25% of the U.S. population. Hyperopia sufferers can see distant objects well, but have difficulty seeing up close objects.

Hyperopia Symptoms

Farsighted people might have headaches or eyestrain, and find themselves squinting or fatigued doing anything which is close-range. If you still experience symptoms such as these with glasses or contact lenses, your eye prescription most likely needs to be updated.

What Causes Hyperopia?

Farsightedness is typically when the eyeball is shorter than normal so the light rays entering the eye focus behind the retina, rather than on it. Many children are born with hyperopia, and some outgrow the problem as the eyeball lengthens with normal growth.

Some confusion exists between hyperopia and presbyopia, since both conditions involve difficulty with up close vision. Presbyopia has a different cause and occurs after age 40.

Hyperopia Treatment

Eyeglasses or contact lenses almost always can correct farsightedness by changing the way light rays bend as they enter the eyes. Your glasses or contact lens prescription will begin with plus numbers, +2.50, +4, etc. when you are farsighted.

Depending on the amount of farsightedness you have, you may need to wear glasses or contact lenses all the time, or only during reading, or work.

If you work prolonged periods on a on a computer screen or do other close-up work for long periods consult with your eye doctor for special work prescription glasses.

Refractive surgery, such as LASIK or PRK, is another option for correcting hyperopia.

If you think that you show signs of one of these conditions, please call us today to schedule your appointment for an eye exam!