Refraction

Refraction

The Refraction test consists of an ophthalmologic evaluation of the patient’s ability to focus and see clearly an object located at a specific distance from the viewer. This test can be routinely performed in order to check a patient’s need for glasses or, in the case of patients who are already wearing glasses or contact lenses, if the glass prescription must be changed. Typically, patients suffering from vision disturbances will undergo this test in order to allow the ophthalmologist to assess the patient’s vision condition, and to determine the actions that need to be taken.

The Refraction test may also be performed in conjunction with other ophthalmologic procedures – for example, follow-up examinations may be performed to monitor the progress of the patient over the course of a therapy cycle or after surgery. In such situations, the supervising specialized health care professional (ophthalmologist) will inform you how often you will need to return for another examination, and will also keep you informed regarding the evolution of your condition. Normally, all individuals should undergo eye examination at least once every three to five years, if they do not experience any vision disturbances. However, in situations where the patient’s vision becomes blurry or otherwise affected, it is strongly recommended that they immediately consult an ophthalmologist in order to investigate the causes of the disturbances.

For individuals of 40 years of age and older, the routine eye examinations should be scheduled at shorter time intervals apart. This is required due to the increased risk of developing glaucoma. Also, patients suffering from diabetes should undergo a thorough ophthalmologic examination at least once per year. In the case of individuals affected by refraction disorders, the normal examinations should be performed every two to three years. Undergoing the Refraction test periodically has a great importance in maintaining your visual acuity. Vision defects worsen over time if they left untreated. Modern therapeutic techniques offer treatment for a large number of eyesight disorders.

Refraction Description

The Refraction tests are performed by specially trained health care professionals, in a hospital or a clinic. Prior to undergoing the examination, the ophthalmologist may administer eye drops – these are used either to dilate the patient’s pupil in order to allow a better observation of the retina, or they may be applied in order to block the papillary accommodation reflex (especially in the case of children and young adults). Once the eye drops have taken effect, the patient is seated in a chair and a special device is employed to examine his or her visual functions. The device used is called a refractor or a phoroptor, and the patient looks through it at an eye chart situated at 20 ft. The phoroptor contains a number of lenses of varying strength, and the health care professional will move the lenses into view one at a time, asking for subjective feedback from the patient regarding the clarity of the chart.

After the Refraction test is complete, the ophthalmologist will be able to determine if you are suffering from hyperopia, myopia, presbyopia or astigmatism, or if your vision is normal. Hyperopia, also more commonly known as farsightedness, is a defect of the eye which causes the patient to not be able to focus on objects found at a relatively close distance; myopia (or nearsightedness) is a defect of the eye which causes the patient to be unable to focus on objects in the distance; astigmatism is an affection caused by an asymmetry in the cornea while presbyopia describes a progressively diminished ability of the eye to focus on near objects. Along with the vision defect, the ophthalmologist is also able to determine the extent of the problem. The Refraction test will provide sufficient information to determine the correct prescription for glasses for each individual, including situations where the patient requires bifocals.

Refraction Related Medication

The pharmaceutical preparations administered under the form of eye drops prior to a Refraction examination are saline-based substances containing an active ingredient which may vary greatly, depending on the purpose of the product. Steroids, antihistamines, sympathomimetics, parasympathomimetics, parasympatholytics, beta receptor blockers, prostaglandins, non-steroidal anti-inflammatory drugs and topical anesthetic agents are commonly used to induce papillary dilation.

One of the most commonly encountered substances used to induce the dilation of the pupil is Atropine; it acts both as a cycloplegic agent blocking the accommodation reflex of the eye and a mydriatic agent dilating the patient’s pupil. It has a long time of degradation (of between one and two weeks), which causes its effects to be better suited for therapeutic use; other agents such as Tropicamide or Penylephrine have superior effects with regards to simple ophthalmologic examinations such as the Refraction test. Atropine paralyzes the ciliary muscle, blocking the eye accommodation reflex; at the same time, it paralyzes the sphincter muscle of the pupil – this allows the dilator muscle to dilate the pupil which will remain dilated. Atropine is also known to relieve pain in patients suffering from iridocyclitis and is a fairly common therapeutic option for malignant glaucoma – however, this pharmaceutical product is not suitable for use in the case of patients affected by or susceptible to narrow-angle glaucoma.

While normally safe to use, eye drops may cause a number of side effects in some patients. Most commonly, the adverse reaction is limited to an increased photosensitivity which may last for up to a few days after application of the drops. Addictive responses may appear if the eye drops are used too often or in excessive quantities, characterized by the reduced ability of the eyes to produce tears, instead relying on the eye drops to perform  the normal role of the tears. Of course, this is not a complete list of all the possible side effects associated with eye drop applications; it is recommended that you consult with your personal physician immediately if you are experiencing uncommon symptoms, as the causes will need to be investigated before any corrective measures may be taken. If you would like to obtain a full list of the possible adverse reactions associated with topical eye agents employed during Refraction tests, it is best to consult with your ophthalmologist or with a pharmacist.