Besides determining what will be the optimum correction for our patients, we also examine the eye from front to back looking for any abnormalities or ocular diesease. Most ocular pathology does not cause symptoms that are evident to the patient until fairly late in the disease process. For this reason, routine examination is the only way to insure that if a patient starts to develop a condition such as Glaucoma or Macular Degeneration, we will find and diagnose the problem early in the disease process. This increases our chances of a good outcome for the patient and the least chance for permanent vision loss.
Because so much of what I do is fairly technical, I thought it might be interesting and beneficial to explain the eye exam process, what I’m looking for and what the results of specific tests tell me about your vision and ocular health. I’ll pretty much walk you through en eye exam, explaining things as we go along. This similar to a course that I teach to optometric technicians over a two hour period, so I’m going to break this process up into a couple of parts.
This is the initial step of data gathering, where we talk to you about how you are doing, any medications you may be taking as well as any specific concerns that you want to be sure to have addressed during your examination.
We also check your distance and near vision with your glasses or contact lenses, or without any correction if you don’t have a current correction.
We also take some preliminary measurements that are used to start both the process of determining what will be your final vision correction solution (either glasses, contact lenses or Vision Shaping Treatment). The first set of these measurements is taken by our Lensometer which reads the Rx out of your glasses. Telling us the sphere power, astigmatic power and orientation of the astigmatism correction as well as the near power of your lenses (if you are wearing a multifocal pair of lenses).
The second set of measurements utilizes a piece of equipment called the 3D Wave.
This amazing device measures your eye glass Rx throughout your entire pupil. It breaks the prescription down into what is called the spherical component of the Rx, the astigmatism portion of your Rx and indicates how the astigmatism Rx is oriented. The 3D Wave gives me three different Rx’s, one in the very center of your pupil, one when your pupil is 3mm in size (similar in size to when you are out on a sunny day), one at 5mm (approximately the size of your pupil in a dimly lit room or outdoors at night). When a patient has a significant change in their Rx due to the size of the pupil, I will use this information to either alter their Rx slightly to improve vision in all conditions or if there is a large enough change in the Rx, create a “low light specific” Rx for glasses and/or contact lenses. Click here to view some example reports from the 3D Wave. This is one of the dianostic instruments that I teach other eye doctors how to use.
The 3D Wave also provides very accurate measurements of the curvature of the cornea (the tissue in the eye that contact lenses rest on).
This data is incredibly useful when fitting or designing contact lenses as well as when looking for an explanation when a patient isn’t seeing as well as they should. I’ve been measuring my patients corneal topography ever since my office opened, but the 3D Wave now gives us this information faster and easier.
The 3D Wave also tells me how “regular” each patient’s visual system is, helping me know just how well I should expect my patients to be able to see once I’ve determined the optimum Rx for them. As we age, the eye changes, specifically the lens inside the eye. In more advanced stages of these changes, I see Cataracts develop. Earlier in this process, while the lens isn’t cloudy like it is with a cataract, the patient’s vision can be adversely effected and require adjustments in their Rx to optimize their vision.
As you can tell, the 3D Wave gives me a wealth of information about my patients’ vision correction needs, and their ocular health. The next measurement that we take is only used on some of our patients, those over the age of 30. We measure the Macular Pigment Density of our patients as it is a predictor for the risk of developing Dry Macular Degeneration.
This is tested using the MacuScope, in a test that takes about two minutes to complete. This non-invasive test measures the density of three pigments in the patient’s macula. Having a low level of these pigments indicates an elevated risk of developing Dry Macular Degeneration. I use this data when discussing each patient’s ocular health and our plan for maintaining it.
The final step in the Entrance Testing portion of the exam is also only evaluated on some of our patients. Those over 40 and all of our contact lens wearing patients.
The Corneal Endothelium is in charge of controlling the fluid concentration in the cornea. Too much fluid and the cornea swells and becomes cloudy. There is a layer of cells on the back side of the cornea that are in charge of controlling the amount of water that is allowed into the cornea. Our specular microscope provides me with numerical and graphical information about the health of my patients’ corneal endothelium (an example of the test results are just to the left). If the corneal endothelium fails, either due to aging of the eye or damage from trauma or contact lens wear, permanent vision loss can occur. For this reason, we screen all of our patients who may have this issue, in order to modify their contact lens wearing habits or other ocular health concerns.
In an upcoming blog post, I’ll discuss the “middle portion” of the exam and in the third installment, I’ll cover the last third and the conclusion of the exam. If you have any questions about the information I’m providing, or would like to know more about anything related to this topic, please email us at firstname.lastname@example.org