Whether you think you need vision correction and are considering contact lenses, or whether you’ve been using glasses or contacts for years, you may be curious about the difference between a routine eye exam and a contact lens exam. Perhaps you’ve never thought about it, always assuming that both are one and the same. The truth is, there are some fundamental differences between these two types of exams.

The information below will give you an overview about each type of exam and explain the difference between the two so that you can ensure you are scheduling the right type of appointment with your eye care professional.

Routine Eye Exam

A routine eye exam exists for the purpose of detecting vision problems, eye disease and general eye health issues. An eye exam can help identify any of these concerns before you are even aware that they exist. It is generally recommended that everyone have a routine eye exam every 1 to 3 years, depending on age, risk factors and physical condition.

What to Expect

Eye doctors use a variety of tests and procedures to examine your eyes.  You will most likely be asked to read an eye chart.  First you will read the chart with both eyes uncovered. Then you will read the chart while you cover one eye (and then the other eye).  Your eye doctor will then perform tests which may or may not include these common tests:

Retinoscopy

For this test, the lights in the room are dimmed and you will be asked to focus your eyes on a target. While you stare at the target, a light will be shined into your eye and flip different lenses in a machine in front of your eyes.  The way the light bounces off of your eye will provide a general approximation of what your prescription (should you need one) will be.

Refraction

This test helps your eye care professional determine the exact level of augmentation that your vision requires. Refraction is done with a     machine called a phoropter. The doctor will show you a series of lens choices and ask you which of the choices looks clearer. Based on your answers, the doctor will be able to determine your level of nearsightedness, farsightedness, astigmatism and/or presbyopia.

Slit-Lamp Examination

A slit-lamp is an instrument that allows your doctor to examine the health of your eyes using a machine that highly magnifies all the structures contained therein. This way, your eye doctor can examine each part of your eye to evaluate them for infection or disease.

There are various other tests that eye doctors can choose to use during an eye exam to determine the general health and well-being of your eyes. A contact lens exam is different in that it focuses on only one aspect of your eye health.

The Contact Lens Exam

If you wear contact lenses or are considering starting, you should make sure to schedule a contact lens exam versus a regular eye exam.  Basically, your eye doctor will need to run tests that will evaluate the surface of your eye’s cornea in order to ensure a proper contact lens fit. Your doctor will also ask a series of questions about your lifestyle and preferences in order to determine the best type of contact lenses to prescribe for you.  The doctor will measure the surface and curvature of your eye using an instrument called a kerameter.  Then your pupil and iris will be measured.  Finally, your eye doctor will select contact lenses for you and instruct you in proper insertion and care.

If you are experiencing vision problems that need to be corrected, you have probably already consulted with a qualified optometrist and have begun exploring the options in order to treat these issues. From special eyewear to laser surgery, there are many different ways to correct common vision symptoms and restore most or all of your vision. You may be considering contact lenses as a possible solution; however it’s important to note that not all vision symptoms can be corrected with contact lenses. Here are some vision problems that contact lenses generally cannot correct:

Extreme Dry Eyes

This is a common problem for contact lens wearers. If you are prone to very dry eyes or have allergies, wearing contact lenses can make your eyes sore and in some cases cause a great deal of discomfort. Those with dry or itchy eyes may feel the need to rub or scratch near their eyes, and this can cause damage to their eyes, sometimes even leading to infection. Over time, this rubbing of the contact lenses can degrade the surface of your cornea making it impossible to wear contact lenses correctly, even with constant lubrication with drops. If you are someone who experiences dry eyes or has allergies that affect your eyes, then it may not be a good idea to treat your vision problems with contact lenses.

Conjunctivitis

In the vision impaired person, a malfunction of the glands that secret the fluids of the eye can cause protein build up while wearing contact lenses. This is a condition called conjunctivitis. If wearing some of the long-term lenses, such as the 30 day soft variety that have been very popular, these glands can begin to produce fluids that are too high in protein levels, and this can cause the capillaries in the eye to become congested and infected.

Conjunctivitis, if not treated right away, can cause a burning, itching redness in the eyes. If not treated, the infection can cause permanent vision problems including blindness. It’s best to seek the advice of an Optometrist before deciding on contact lenses if you are prone to eye infections or have underlying medical problems that may compromise your successful wearing of contact lenses.

Blindness

Obviously if you are partially or fully blind in one of both eyes, you will not get improvement for these vision symptoms by wearing contact lenses. Blindness is a cellular issue and a breakdown of the actual eye tissue, either congenitally or as a result of illness or injury. The only benefits of wearing contact lenses for a blind patient would be cosmetic. Unfortunately, wearing contact lenses will simply not help. One exception to this is an individual who is classified as legally blind, but still has some vision. Contact lenses may help make that vision slightly clearer.

Remember to consult with your eye doctor before making a decision to use contact lenses, always purchase high quality lenses from an eye care clinic to avoid any problems, and use them carefully to avoid any injury or infections to your most precious asset, your eyesight.

If you go to an eye care professional for all of your optical needs, then reading your eyeglass prescription is something that you may never have to worry about. However, if you ever plan on trying to order a pair of eyeglasses online without visiting the optician’s office it’s imperative that you know how to properly read your prescription it you want to get a pair of glasses that you can see out of.

You prescription will often be delivered as a pair of numbers – one number under the Latin abbreviation of OS (your left eye) and the other under the Latin abbreviation OD (your right eye). The farther away either number is from zero in either direction (plus or minus) the worse your eyesight is and the more correcting your vision will need for you to be able to see clearly.

If the numbers in your prescription are in the positive it means that you are farsighted, or that you have problems with seeing things close to you; if the numbers are in the negative it means that you are nearsighted or that you have difficulty viewing objects that are far away.

If you suffer from astigmatism you’ll see three numbers in your eye glasses prescription – the first of which will represent both of the numbers seen in a prescription of a person who doesn’t have astigmatism, the second number will represent the severity if the astigmatism – the larger the number here the greater you are effected by the astigmatism. The third number in the prescription of a person who suffers from astigmatism will be between zero and one hundred and eighty and this number reveals the location of the astigmatism. For proper corrective treatment of astigmatism, the technician making your lenses needs to know the location of the astigmatism in degrees as well as the level of severity.

Each of the numbers that you see in your eyeglass prescription is crucial to the final result, the numbers may be whole numbers or they may be fractional (like 1.25, representing one and one quarter) and the exact number is required for you to be able to see clearly. The numbers represent “diopters” which is the unit of vision correction from which your lenses will be manufactured. If you are off by even a fraction of a point when relating the information of your diopters, your glasses may not be as precise as they need to be to properly correct your vision. When relating all of the numbers and symbols of your eyeglass prescription for an order it’s imperative that you be precise or you will receive a pair of glasses that won’t properly correct your problem.

There are other considerations when contemplating ordering prescription glasses online that don’t necessarily have to do with your prescription itself, but that could seriously affect the corrective properties of your glasses. The most common number not represented in your prescription that you’ll need to know when ordering glasses online is the distance between your pupils, or your PD. There’s a good chance that your PD will be imprinted somewhere on your old glasses, if you’ve still got them – if you don’t the number isn’t all that difficult to get. You’ll need a ruler that measures in millimeters and a mirror. All you do to get you PD is to look straight ahead into the mirror and hold your ruler directly below your eyes to measure the distance between the centers of your pupils. The most common distance for a PD is between 58 and 70 mm, so if your distance is either well under 58 or well over 70, you might want to measure again.

Reading your prescription and ordering glasses without visiting the optician is certainly possible, but if you have any questions about what you’re reading it’s highly advisable to visit your eye care professional to be certain that you get it right – eyeglasses are expensive and you certainly won’t be able to return a custom pair, so make sure you get everything right before you make anything final.