Prescription and centering: the first step to get the perfect glasses
Do you notice that you have lost vision quality? Do you suffer from eye irritation, headaches or visual fatigue?
All these symptoms could respond to an incorrect vision. If so, an eye exam could give you the answers that will help you solve the problem, whether you wear glasses or contact lenses or not. Our visual ability changes over time almost without us noticing, so it is worth checking that we have not undergone changes in our prescription, especially if you are thinking about buying new glasses.
But what are the steps to follow?
- Visit your ophthalmologist or your optometrist optician.
- Ask for an eye exam.
- Centering of the lenses.
- Check up periodically.
These are the basic steps to follow to keep our eye health under control and achieve a better visual quality. Do you want to know more about it?
Optician or Ophthalmologist? Is there any difference?
Probably your first question is: What is the best place to have my eye exam? If so, you should know that you have two equally valid options: in the ophthalmologist's office or in the optician's office. But what are the differences between one and the other?
Ophthalmologist: They will not only check your visual ability. Being a health professional, they can diagnose and treat pathologies or diseases of the eyes. If your problem goes beyond a simple lack of clarity, you should go to their office.
Optometrist Optician: They will perform the exam in the optician’s shop without a prior appointment (although it is recommended), so it can be considered a more dynamic procedure. Also, as soon as you have your recipe, you can choose your new frame in the same establishment, which will avoid having to move twice.
Regardless of the decision you make, there are several things you should keep in mind before submitting to the test:
- If you are taking medication, you have a chronic illness or you are pregnant, you must notify the professional who is going to examine you beforehand since all these circumstances can affect the visual capacity and cause deviations in the results.
- It is preferable that you do not use contact lenses in the 24 hours prior to the exam.
- Ideally, you have eaten and drunk properly and are relaxed during the exam.
- Take your time during the tests, it is important that you are sure of your answers; after all they will determine the glasses or lenses that you will wear later.
Vision test. What does it consist of?
Once you have decided between visiting the ophthalmologist's office or going to the optician’s shop and you are sure to meet the optimal conditions to examine yourself, the qualified professional will examine your eyes using different tools and devices designed for this purpose. The steps to follow are those:
- Preliminary measurement: They will do it in case you do not have any previous reference of your prescription (a previous recipe or some glasses that you were already using, for example). With the help of an autorefractometer, the optical power of both eyes will be measured to evaluate your visual capacity. If you used glasses before, you will be tested in order to assess any possible change in your prescription.
- Measurement of visual acuity: With this test it will be determined to what extent you are able to perceive contrasts, details or contours at a certain distance. To carry out this measurement a phoropter or the typical test glasses are used. In both cases, the optician or ophthalmologist will be placing different lenses while you read the classic boards with letters that go from larger to smaller. This way you can check which lenses allow you to see more clearly.
Since visual acuity varies by age, eye exams are not the same for children and adults. For example, from the age of about forty years, the near vision will be also assessed.
Centering of the lenses. How the glasses adapt to you.
If you decide to use glasses and you know what frame you want, to achieve optimal vision, it is best to center the crystals taking as reference the pupillary height (the distance between the inner edge of the glass and the center of each pupil) and the interpupillary distance (the distance between the center of each pupil and the nasal bridge). This procedure serves to establish the optical center of the lenses, that is, the point of the lens that the rays of light go through without suffering any type of deviation (it is the thinnest point in concave lenses and the thickest point in convex lenses). This achieves optimal vision correction.
In addition, to achieve maximum comfort, the frame adapts to the face of each person. Most frames have adjustable rods and many also incorporate adaptable plates. The necessary adjustments are made free of charge in any optician store.
Keep control of your vision. Check up periodically.
Unfortunately, our current pace of life increases the chances of developing visual defects. The LED lights of digital screens, television or hours of study are a great effort for our eyes and can lead to a progressive deterioration of our visual capacity.
For this reason, the ideal is to have regular eye exams. In general, it is enough to check up each one or two years, but this can vary according to age. In the case of children this is especially important since their visual capacity can change rapidly. It is advisable to perform the first study at the age of two or three years to confirm that they do not suffer from any visual impairment. From there, an annual check-up would be enough (also if they wear glasses already).
In the case of adults, the more advanced the age, the more likely it is to experience sudden changes in visual acuity, as well as to develop various pathologies. For a young or middle-aged adult a check-up every two years will be enough, but an older adult should have an eye exam annually.