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Opticians design and fit eyewear, this includes spectacles, contact lenses, low vision aids and other specialized optical devices. We interpret the prescription from the eye doctor and determine the best way to fill it. Every pair of glasses or contact lenses is custom designed for that patient’s specific needs. We are also fashion consultants. Glasses and contact lenses are fashion accessories, so we have one foot in the health sciences and the other in the retail world.
Let’s take a look at what is involved in designing a simple pair of glasses. The essence of what an optician does is to select, from all the different products available, the very best combination of these products, to fit the visual and aesthetic needs of the individual patient, based on a number of variables. These variables include the patient’s prescription, occupation, hobbies, sports they might play, facial and ocular measurements, fashion preferences and more. The eyewear must fit safely and comfortably into the patient’s lifestyle. This requires an extensive patient history gained through discussion with the patient. Once the patient’s needs and desires are known we can begin to suggest the best combination of frames, lenses, coatings and other special treatments. What the doctor’s prescription tells us is simply the power needed to maximize the patient’s visual acuity. We have to decide the best way to create that power, and there are literally hundreds of ways to do that. We get to be very creative in our suggestions to our patients
Let’s start with eyeglass lenses. As a matter of fact, let’s just start with lens materials. It used to be that all lenses were made of a particular type of glass, and then plastic lenses were developed. So we had a choice between glass and plastic. Now there are many different kinds of glass available and many different types of plastic as well. Would this patient benefit from crown glass or hilite glass or index 1.8 glass? Would the patient be better off with CR-39 plastic or polycarbonate plastic or trivex plastic or any number of other high index plastics? This is not the entire list of lens materials available so you can see why we need to know what the patient is going to be using the glasses for, before we can suggest the best material. Certain materials will make vision sharper, others will make the glasses thinner or safer, still others will make the lenses more scratch resistant or selectively filter out specific types of radiation (e.g.: ultraviolet, infrared, visible). We also determine what combination of front surface and back surface lens curvatures would give the patient the best visual acuity and widest field of view with the least distortion? We then need to choose a lens thickness appropriate for their use.
After the lens material is selected, we can determine if the patient would benefit from any of the lens treatments available. Would they be a good candidate for an antireflective coating, a UV coating, a color coating, a scratch coating, a hydrophobic coating, an oleophobic coating or a mirror coating? For example; if you decide on a mirror coating for a pair of sunglasses, what color should it be, should it be solid, gradient or double gradient? Should it be a solid or flash mirror?
There are many manufacturers and types of antireflective coatings; some work better than others, some are easier to clean, some are more scratch resistant and some cost more than others. Which should we suggest?
Now we can decide if any other specialty lenses might be helpful. How about a photochromic lens (photogrey or transitions for example) or a polarized lens?
If the patient is going to use these as sunglasses for fishing the Optician has to know that polarized lenses will make fishing easier and more enjoyable. If the patient is an airplane pilot the optician has to know that polarized lenses could make it hard to read certain airplane instruments and this could be very dangerous.
If the patient requires a multifocal lens for near or intermediate use, which type of multifocal would be best? Should we use a bifocal, a trifocal, a quadrafocal, a blended segment, a progressive, or an occupational segment? If we choose a bifocal which type of bifocal should we use? Should we use a flat top, a curve top, a B-ribbon, an R-ribbon, a panoptic, an executive, a round, a blended or some type of Ultex bifocal? If we use a flat top bifocal what size would be best for this person’s purposes? Should we use a 20mm, a 22mm, a 25mm, a 28mm, a 30mm, a 35mm, a 40mm or a 45mm flat top? These are some of the choices available for only one style bifocal. Imagine all the possible combinations. A few of the things opticians need to consider, when deciding which bifocal to use, include: the prescription, the patient’s height, the patient’s posture, any asymmetry of the patient’s facial features, the amount of near use, the size of the patient’s near work area, the pantoscopic angle of the frame, and the list goes on.
After selecting the lenses we need to pick out a frame to hold them. When choosing the frame we must use one that is the correct size for the patient’s physical characteristics and compatible with their prescription. It must have the correct bridge size, eye size and temple length. Frames can be made of various plastics (cellulose acetate, propionate, acrylic, optyl, nylon) and metals (gold, stainless steel, titanium, phosphor bronze, monel, nickel silver, aluminum and others). Depending on what the glasses are going to be used for, certain materials may be preferred because that material is stronger, more flexible, safer, more hypoallergenic, harder, softer, lighter, less corrosive, more adjustable or maybe it can just be uniquely colored. Other frame features that need to be considered would include: hinge type, lens suspension/mounting type, temple style, etc.
The frame must also have aesthetic appeal to the patient. We must make our patients look better as well as see better. We become fashion consultants when discussing which color designer frame goes best with a particular outfit. Many patients are as concerned with their appearance than whether or not they can see well. Glasses are eye jewelry and very cool fashion accessories.
There are so many different lens and frame options because people don’t wear the same type of glasses to play racquetball, that they do to go fishing, that they do to work on the computer, that they do for scuba diving, that they do for driving, that they do for going out to dinner, that they do for welding, that they do for skiing, that they do for swimming and the list goes on to include almost any activity you can think of.
After the lenses, frames and other options are selected the optician must take certain measurements and make exacting mathematical calculations to insure that various reference points on the lenses are oriented properly within the frame and in relation to the patient’s eyes. We want these points to line up with the patient’s visual axes when their eyes are in the primary position and also when their eyes converge to view objects at close range. One measurement that must always be taken is an accurate monocular interpupillary distance measurement. This locates the patient’s two visual axes so that we can place the optical centers of the lenses right on these axes. The proper location of the optical centers of the lenses within the frame is important because the patient sees best when looking through these reference points. If the patient is not looking through the optical centers of the lenses they could experience such symptoms as blurry vision, headaches, fatigue, nausea or double vision. Feeling badly is no fun and seeing double could be dangerous. The only time we want our patients looking through the lenses at a point other than the optical centers is if prism is prescribed, and this requires another set of calculations for proper orientation of the lenses. If the lenses are going to be multifocals other measurements and calculations are necessary for proper placement of the reading and/or intermediate areas of the lenses. If it is a simple bifocal we need to measure accurate monocular near interpupillary distances and segment heights. From these measurements we must calculate the seg inset, the total inset and decentration and the seg below/drop. If these measurements and calculations are not accurate the patient could be looking through the distance portion of the lens when they are trying to read books, or the reading portion when they are trying to drive. Also, the patient could experience the other symptoms listed above for improper optical center placement. So if you experience headaches or see double when you read it may not be that the power of the lens is wrong, it may just be that the measurements and calculations were not done correctly.
Other types of common calculations that opticians must perform when designing spectacles would include compensating for change in vertex distance, or compensating for vertical prism imbalance at the reading level for anisometropic presbyopes.
After the eyewear is designed (this design process can easily take an hour or more) the optician sends the job to the lab to have the glasses made according to his or her specifications. Some opticians do their own lab work but most jobs get sent to a wholesale laboratory for fabrication.
When the finished pair of glasses comes back from the lab the Optician must verify that the work done by the lab is perfect. The Optician must check each pair of glasses to make sure that the following items are correct: the sphere power, the cylinder power, the orientation of the axis, the location of the optical center and datum line, the decentration and inset, the seg height, the base curves, the bench alignment, and the lens thickness. The optician must make sure that the lenses are the right size and shape and that they fit perfectly into the frame. The optician must make sure that the lenses and coatings are not scratched or chipped, that the bevel on the edge of the lens is correct and that the lab has not damaged the frame. If anything is wrong the glasses must be returned to the lab and the problem corrected. If everything is correct we can notify the patient that their glasses are ready.
When the patient returns to pick up their classes the Optician begins the delivery process. This includes adjusting the frame to the patient’s head so that the glasses stay in place and do not slip down the patient’s nose and so they don’t hurt the patient’s nose or ears. There is a real art to adjusting the frame correctly. The optician starts by adjusting the bridge, then checks to make sure the frame is straight on the patient’s face, then makes sure the lenses are the same distance from each eye, then makes sure the face form of the frame front is correct, then makes sure that the lenses have the proper tilt (pantoscopic tilt and face form), then places the bend in the temple at the proper location and finally contours the ends of the temples to the patient’s head. After the frame is adjusted the optician must instruct the patient in the use and care of the glasses. This includes how to use and what to expect from the performance of their single vision or multifocal lenses, the best way to put their glasses on and take them off, the type of recommended case and cleaning cloths and the cleaning process for the specific lens material or coating. The good Optician will then suggest that the patient return for periodic “tune ups”.
If everything is done correctly, the patient will end up looking great and with a comfortable pair of glasses that fit conveniently into their lifestyle, and through which they see clearly and safely.
This is a very involved and complex procedure that is necessarily different and therefore customized for each individual patient. For this procedure to work properly the optician must be a highly skilled and educated professional who stays current with all the new products that are continually being developed. Consumers should be very concerned that the individual designing and fitting their eyewear is formally educated and licensed.
Opticians also design and fit contact lenses. The contact lens fitting process is at least as involved as that for spectacles. Space will not allow me to describe all the specialized equipment used by contact lens fitters. Contact lenses are available in even more specialized plastic materials than spectacle lenses, there are many different lens designs in each material and there are almost as many different fitting philosophies as there are contact lens fitters. Then there are the disinfecting solutions, wetting solutions, storing solutions, cleaning solutions, enzyme solutions and rewetting solutions. The optician must know which solutions go with which contact lens materials. When designing contacts for a patient, the fitter needs to consider the patient’s prescription, how much the patient tears, how often and how well the patient blinks, the diameter of the patient’s iris, the size of the patient’s palpebral fissure, the curvature (how steep or flat) of the anterior corneal surface, any allergies the patient may have, any medications the patient is on, whether the patient has any active ocular pathologies, the patient’s daily environment, along with many other factors. These factors will tell the Optician whether the patient is a good candidate for contact lenses (there are many contra indications to contact lens wear). These factors will also determine the best contact lens material, the back (base) curve, the front (power) curve, the thickness, the peripheral curves on the lens, the lens diameter, the final lens power, whether the lens will be spherical, front toric, back toric or bitoric, the color of the lens, and other lens parameters. Then the fitter needs to explain to the patient how to insert and remove the lenses from their eyes, how to disinfect and care for the lenses, how much and how often they can wear the lenses, and must create a schedule for follow-up visits to insure the health of the patient’s eyes and eyelids. The dispensing of contact lenses is regulated by the FDA (Food and Drug Administration), and their web site contains an endless list of cautionary statements and warnings concerning the wearing and fitting of contact lenses.
When all is said and done, it seems to me that the Optician spends a great deal more time interacting directly with the patient than the individual who wrote the prescription, and that the optician has more of an effect on the final product used to correct the patient’s vision. It is not uncommon for Opticians to spend an hour or more with their patients before the pair of glasses is even ordered. When an optician fills a prescription he or she has literally hundreds of different ways to do it, and although an incorrectly filled prescription for eyewear rarely has life or death consequences, it can have a very direct and serious effect on the health, safety and welfare of the patient.
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