What to Expect at Your Cataract Exam - The Examination for Cataracts & Cataract Surgery
Reviewed by: Jason Jacobs, MD
In order to detect and diagnose a Cataract it is usually necessary to have a comprehensive eye examination. A comprehensive eye exam should include the following information gathering, tests and measurements:
Your Medical, Family & Eye History
A thorough history will be taken from you regarding your general health, any previous eye problems or conditions that you have experienced and a review of any problems that you might be experiencing with your vision or your eyes. Make sure to include any accidents, trauma or infections that you have had in your eyes. This will be important information to provide to the technician or eye doctors during the screening process. If you have any chronic health problems such as diabetes, heart disease, asthma or hypertension, even if they are currently stable, it is important that you relay this information.
Be sure to tell the technician or eye doctor about any medications you are taking for any medical conditions, including over the counter medications or eye drops that you may have been using. It is particularly important to tell them if you are taking or have ever taken medications for prostate problems, especially Flomax. Also make sure you tell the technician or eye doctors if you have taken or are taking cortisone type medications for asthma or any other health problem as well as any medications for anxiety, depression or other psychiatric problems. They may be important to consider in your examination and may be important in understanding how or why you may have developed a Cataract.
Your family history will be carefully reviewed as well. Please tell the technicians or eye doctors about any medical or health problems that run in your family. Most importantly, tell them about any eye problems such as glaucoma, macular degeneration or cataracts that your family members may have had. Also be sure to tell them if any family members have had cataract surgery or lens implants. Cataracts tend to run in families.
The Eye Examination
Visual Acuity Measurement-Your eye examination will begin with a technician measuring your vision, or visual acuity-both with your current eyeglasses or contact lenses and at both far away distance and up close to test your near vision for reading. Chances are that if you wear eyeglasses or contact lenses, some of the letters on the “Big E” eye chart will be blurry without them. The technician will ask you to read a chart projected across the examination room that consists of numbers and letters that get progressively smaller and more difficult to read as you move down the chart. This test, called “Snellen Acuity” or just “Visual Acuity” it is an important first step to understanding how well you see.
Ocular Motility-Next, the movement of your eyes, or “Ocular Motility” will be evaluated in order to understand how well the eye muscles function together and how effectively they move your eyes into the different positions of gaze.
Pupil Reflexes-By shining a fairly bright light in your eyes, the reaction of your pupils to the light will be evaluated. By shinning the light into your eyes in different directions, your doctor can learn a great deal about how well your Optic Nerve is functioning.
Refraction-The refraction test helps your doctor determine if a change in glasses would improve your vision. For patients who wear eyeglasses or contact lenses, you have probably experienced the “which is better” test called refraction. Checking your refraction helps to determine the most accurate eyeglass or contact lens prescription necessary to fully correct your vision and how well it can actually be corrected. This entails having you sit behind an instrument called a Phoroptor, so that the technician or doctor can present a number of lens combinations in order to see which corrects your vision most precisely.
Slit Lamp Biomicroscopy- A Slit Lamp Biomicroscope is an instrument that provides the technicians and Cataract Surgeons with both high magnification and special illumination. Using this instrument it is possible to examine the condition of your eyelids, eye lashes, eyelid margins and tear film. The Slit Lamp will also be used to carefully examine the sclera or white of your eye and the cornea or clear dome shaped lens on the outside of your eye. By focusing the Slit Lamp through the pupil or dark center of the iris-the colored part of the eye-your eye doctor will be able to examine the health of the Crystalline Lens, which is where Cataracts form. Using the Slit Lamp with its high magnification and special illumination that allows for the cross sectioning of living tissue, it is possible to examine the Crystalline Lens in detail and identify the location, position and density of a Cataract.
Tonometry- In order to check for one of the signs of Glaucoma, 1-2 eye drops will be placed in your eyes so that the fluid pressure, called Intraocular Pressure (IOP) can be measured while you are behind the Slit Lamp. In some instances Tonometry may be performed a Tono Pen, which is a handheld instrument.
Pupil Dilation- Once your Cataract Surgeon has completed the examination of the “front of the eye”, he or she will then examine the health of “back of the eye”. At this time, additional eye drops will be placed in your eyes in order to dilate or widen your pupils. Pupil dilation is important so that the eye doctors can examine the health of the structures in the back of your eye including the Retina and its blood vessels and the Optic Nerve. After the dilation drops are placed in your eyes, it will usually take anywhere from 15 to 30 minutes for the eye drops to fully work and dilate your pupil. The doctor may use a combination of bright-lighted instruments, called Ophthalmoscopes, to conduct this examination. In addition he or she may also use specialized magnifying lenses with the Slit Lamp to thoroughly evaluate the Retina and Optic Nerve.
Once the above series of tests are performed and you have been found to have a Cataract, it is possible that some additional testing will be performed to understand more about how the Cataract is affecting your vision. These tests may include:
Glare Testing-If you have Cataracts your vision may be significantly impaired in certain lighting conditions and quite normal in others. Glare testing gives the Cataract Surgeon information about how your vision changes and what symptoms of glare you may have with a series of different lighting sources.
Contrast Sensitivity Testing-Contrast sensitivity testing may be useful to determine whether the formation of Cataracts is affecting your ability to discriminate shades of gray. Cataracts often cause a subtle dimming of vision such that there is a loss of contrast sensitivity, which can be disturbing.
Potential Acuity Testing-Potential Acuity testing gives the Cataract Surgeon information about what your vision would be like upon the removal of your Cataract. In some respects, it is a way of predicting what your vision might be like after Cataract Surgery.
Based on the results of all of the testing, if your Cataract Surgeon believes that you are a good candidate for a Cataract operation, he or she will most likely order some additional testing depending on the type of Lens Implant you are going to have. These additional tests may include:
Partial Coherence Interferometry-This test uses a laser to measure the length of the eye and is performed with an instrument called an IOLMaster. Measuring the length of the eye is an important factor in calculating the strength or power of the intraocular lens implant (IOL) that is used to correct your vision after Cataract Surgery. The IOLMaster is a very sophisticated instrument that uses a laser to obtain the measurement and is very accurate.
A-Scan Biometry- Another technique that can be used to obtain the necessary measurements for the Lens Implant calculation is called A-Scan Biometry, which is an ultrasonic method of measuring the length of the eye. There are two methods of A-Scan that can be used-both can be conducted right in the Cataract Surgeon’s office with little if any discomfort at all. With the applanation biometry method, an ultrasound probe is placed directly on the cornea, which slightly indents the surface after some numbing drops have been placed in the eye. With the immersion technique the ultrasound probe does not come into direct contact with the cornea, but instead uses a fluid between it and the probe to take the measurement. Your Cataract Surgeon will decide which method of eye length measurement to use in order to get you the best possible results of your Cataract and Lens Implant Surgery.
Corneal Topography-Corneal topography is a testing method used to digitally map the contour of the surface of your cornea. This information is of particular use if you have a significant amount of astigmatism and your Cataract Surgeon is going to correct that astigmatism during your Cataract Surgery by using either an astigmatism correcting toric lens implant or Limbal Relaxing Incisions (LRI).
Ocular Coherence Topography (OCT)- Optical Coherence Tomography or OCT is a high technology imaging test that allows eye doctors to produce high resolution cross sectional views of the structures of your eye without ever touching it. In some ways this is analogous to CT Scans that are used to “image’ organ systems in other parts of your body. The OCT test consists of multiple scans, and each scan takes about 45-60 seconds, the total test time is between 10-20 minutes. Since it is a non-contact, non-invasive testing method, it is not uncomfortable or difficult for patients. OCT may be recommended if you are having a near vision presbyopia-correcting lens implant in order to confirm the health of the Macula.
Testing and examination for Cataracts requires a comprehensive eye examination. For people concerned about Cataracts, their Cataract Surgeon will be able to recommend the right level of testing in order to get the most accurate diagnosis, best prognosis and ultimate results from their Cataract and Lens Implant Surgery.
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