Examinations for wearing contact lenses with referrals for wearing contact lenses
Ophthalmological examination for wearing contact lenses
During the first examination for contact lenses, it is necessary to do a complete ophthalmological examination to make sure that the person is a good candidate for wearing contact lenses. At the beginning of the examination, it is necessary to define the wishes and needs of the patient from a conversation with the patient, for example, whether wearing contact lenses is intended for daily wear as a replacement for glasses or for wearing during sports once a week, for the purpose of correcting several different focuses of distance and near vision multifocal lenses, aesthetic reasons such as iris color change, etc.
During the examination, visual acuity, refraction of the eye with correction and corneal keratometric values (curvature of the front surface of the cornea) are determined, essential for the so-called "fitting" or determining the base curvature of the contact lens that best fits the patient's cornea.
What is and when is a biomicroscope examination necessary?
An ophthalmologist can perform additional diagnostic tests, such as a biomicroscope examination and an examination of the fundus of the eye to diagnose eye conditions and diseases that may be a contraindication for wearing contact lenses and need to be treated first.
The biomicroscope determines the size of the pupil and iris, important for choosing the optimal contact lens design, especially if the patient is motivated to wear a semi-hard contact lens. In order for contact lens wear to be successful, an adequate tear film is needed to keep the lens and cornea adequately hydrated. At the same time, a fluorescein and TBUT test (Tear Break Time Test) is performed, which determines the stability of the tear film, as well as tests that determine the amount of tears produced, all of which can affect the adequate choice of contact lens. Diagnostic tests can then be performed, such as corneal topography, with which the doctor will determine the "relief" image of the cornea and in addition to determining the curvature of the cornea, precisely define the measurements essential for the optimal determination of contact lenses.
In a conversation with the patient, the ophthalmologist will determine the best options for contact lens and will then make a trial test of the selected contact lenses. Once the lens is on the cornea, the patient waits about 20 minutes for the eye to fully adapt to the trial lens and then a control examination is made with a biomicroscope and the final visual acuity with the contact lens is determined.
As the last step of the first examination for contact lenses, the patient is educated on how to insert and remove the lens from the eye and how to disinfect it. The patient will be taught the proper maintenance of contact lenses, especially those that are worn for two weeks or a month. Hygiene, proper contact lens handling and disinfection are the basic steps for successful long-term contact lens wear.
When to come to the ophthalmologist's check-ups?
A control examination is ordered within a few weeks after start of wearing the contact lens, and of course, earlier if necessary, to determine the control visual acuity with the contact lens, how well the lens is positioned on the cornea and whether there are any subjective disturbances when wearing the contact lenses in terms of discomfort or other disturbances (burning, blistering, allergic reactions, etc.). In case any of the mentioned parameters are not met, a new contact lens is re-determined (fit). In the event if toric contact lens for the correction of astigmatism or a multifocal contact lens for the correction of presbyopia are used, additional time and repeated fitting are required to obtain a satisfactory result.
Prescribing contact lenses
After an adequate contact lens has been determined according to all the necessary criteria, the contact lens is prescribed and the prescription must contain information about dioptric strength, lens curvature, lens diameter, lens name and manufacturer.
Contact lenses can be classified according to different criteria: according to their purpose, they are divided into corrective, cosmetic and therapeutic; according to the material to soft (hydrogel and silicone hydrogel material), most often prescribed with a different proportion of water from 30 - 80%, hard gas-permeable or semi-hard contact lenses (RGP - Rigid Gas Permeabile), according to the length of wear (daily or for prolonged wear) and by duration (daily, fortnightly, monthly, quarterly or annually).
Routine control ophthalmological examinations for contact lenses will be sufficient every year to monitor visual acuity and earlier in case of any disturbances or if it is necessary.
If you have noticed changes in your vision, react promptly and book an appointment for an ophthalmological examination.