Dentistry is a field that is mostly governed by accuracy and precision. As dentists, you wouldn’t want to drill just around or near the vicinity of the cavity, you want to drill the cavity at precisely the exact point it needs to be drilled, following dental principles which pretty much calls for accuracy and precision. But doing something accurately and precisely is a challenge in and of itself. Imagine doing it on a surface where your thumb is actually bigger than the surface you are working on. Hard to imagine and even harder to do, but the introduction of magnification or loupes in our field has made this challenge easier to deal with. That’s why dental loupes have gained a lot of popularity from the time it was introduced and even more so now that it has become a valuable tool, something some dentists and even dental trainees/ students have come to rely on heavily and frequently. And without a doubt dental loupes for bench test preparation play a significant role.
A loupe is a simple, small magnification device used to see small details more closely. Unlike a magnifying glass it does not have a handle and its focusing lens are contained in an opaque cylinder or cone or fold into an enclosed housing that protects the lenses when not in use.
Types of Dental Loupes
Types of Dental Loupes According to Lens System
– Galilean Loupes
This is the more common system and is also known as lower magnification loupes. The practical range is limited to x3.5 or less, as the system is limited by spherical aberration. The flatness of the field from top to bottom and left to right begins to distort the image quality as magnification increases. An additional consideration is that all Galilean lens systems produce a halo effect at the periphery of the visual field which, in some cases, may be bothersome. They are, however, relatively light in weight and low cost. And recent developments in optical technology have led to the manufacture of Galilean loupes with improved optical quality. This may mean that the heavier Prismatic loupes will become outmoded, even for greater magnification.
– Prismatic Loupes
These provide the highest optical quality available today. In Prismatic loupes, the passage of light is lengthened through a series of internal reflections via a Schmidt prism, thus allowing the barrel of the loupe to be shortened sufficiently for spectacle or headband mounting. These loupes provide improved quality of magnification, wider fields of view and greater depth of field. The disadvantages are that they are heavier, have long barrels and are more costly. They can be used for all levels of magnification.
Positioning of the Optics
– TTL or Through the Lens Loupes
TTL loupes have the optics built into the glasses, with the specifications (such as inter-pupillary distance) customised to your eyes. Because of this, a detailed examination and fitting are required for these types of loupes.
- Lighter weight
- Wider field of view (as optics are closer to the eyes)
- Optics will always be in the right position
- Much more expensive
- Much more difficult to communicate with patient as they cannot be flipped out of the way
- Poor resale value (as they are only suited for the person they are set to)
– Flip Up Loupes
Flip up loupes have the optics attached to a moveable arm, and can be manually adjusted to suit anyone.
- Much cheaper
- Better for communicating with patients as they are easily flipped when not required
- Better resale value
- Easier to add prescription
- Smaller field of view
WHY DO WE USE LOUPES?
There are 3 principal reasons for adopting a Loupe in dentistry (1):
– To Enhance Visualization of a Fine Detail.
There is no doubt that magnification is becoming more popular as clinical techniques become increasingly demanding. This magnification allows you to see critical details more clearly that normal viewing won’t permit.
– To Compensate the Loss of Near Vision (Presbyopia).
Studies show that the working distance significantly increases as we age and by using loupes, however, the working distance can be kept at a comfortable constant, also ensuring upright posture throughout the working life of the dental practitioner.
– To Ensure Maintenance of Correct Posture.
Correct operating posture becomes doubly important for the dentist who uses magnification, as maintenance of the transverse axis of the eye in the horizontal plane is essential in order to avoid disorientation. There is plentiful evidence to support that the use of appropriate loupes diminishes and, in some cases, eliminates chronic neck and back pain. These studies have demonstrated that appropriate selection, adjustment and the use of magnification systems facilitate the adoption of a more upright posture.
HOW TO CHOOSE YOUR DENTAL LOUPES:
Choosing dental loupes can be confusing and complex if you don’t know what to focus on first before delving into other things like brands and other stuff. To make it simpler and less confusing here are several steps that you can follow:
– Working Distance for Dental Loupes
Working distance is distance at which a loupe will focus. You need to carefully select your working distance because an appropriate one will help you maintain the correct posture throughout your procedure. To measure the working distance, sit in an ergonomic position, as if you were working on a patient and take a tape measure and measure the distance between the bridge of your nose and the area of the patient you would be working on (2).
See video below showing how to measure the working distance:
Usually, your working distance will be close to what is shown in the table below (3)
- Height: <5’7″ (170cm)
WD(sitting): 34cm (14″)
WD (standing): 42cm (16″)
- Height: 5’7″-6’4″ (170-193cm)
WD(sitting): 42cm (16″)
WD (standing): 50cm (20″)
- Height >6’4″(193cm)
WD(sitting): 50cm (20″)
WD (standing): 55cm (22″)
– Depth of Field
After getting your working distance to better understand loupes there are certain concepts you need to know. The first concept is depth of field. The depth of field refers to the ability of the lens system to focus on both near and far objects without having to change position. It determines how much you can lean into and away from an object. Loupes are made to stay in focus at specific working distances. However, this distance is actually a range. So, if a loupe has a working distance of 18 inches and has a depth of field of 5.5 inches it means the loupe will remain in focus from a distance of 15.25 inches to 20.75 inches, or 2.75 inches on either side of the working distance.
– Field of View
Next concept you need to understand is what field of view is. The field of view is everything that is visible at once when looking through the lenses of the loupes. There are several factors that can affect the field of view. They are:
– Distance from the Lens
the closer your eye is to the lens the larger the field of view will be and vice versa.
the higher the magnification the smaller the field of view will be and vice versa.
– Declination or Viewing Angle
Another concept to take note of is the declination or viewing angle. This is the angle at which a lens is set to a horizontal reference line drawn from the superior auricular crevice to the bridge of the nose and will determine the sight line. When operating, the greater the angle with respect to this line, the greater the neck tilt necessary to view the object. It is ergonomically important to make sure that this angle is correct for the individual, in order to minimize strain on the neck, back and shoulders.
Here is a diagram showing these concepts to better understand them:
– Choose Your Magnification.
The size of the image viewed through the loupe is determined by the amount of magnification. You need to determine on your own what magnification you most feel comfortable with and allows you to work more effectively. For dentistry the most common are x2.5 magnification and x3.5 magnification. The table below further explains these two magnifications.
Magnification X 2.5
- wider field of view can see multiple quadrants
- greater depth of field
- Image not as magnified/large
- A lot of people like the vendor representatives and some schools (like Buffalo University for pre-clinic) suggests/requires to start with this magnification if you are a beginner because higher magnification at the start can sometimes get a bit disorienting or confusing and for some people a kind-of-motion-sickness sensation is experienced that a period of adjustment on this magnification is suggested before trying out for higher magnification
- Used for general dental procedures like in operative and fixed procedures
Magnification X 3.5 or Higher Magnifications
- Narrower field of view restricted to a single quadrant– Although nowadays, there are some brands that offer the x3.5 magnification but with an EXPANDED FIELD to compensate for this, so it does not become much of disadvantage
- smaller depth of field
- Image are larger
- For students and trainees, some people suggest starting with this magnification instead of starting with x2.5 then buying another pair when you reach D3 or D4. (if you’re looking to save a bit of money). Especially when you don’t feel the motion like sickness sensation that other people have experienced and can use this magnification without any problem
- For some new users there is a steeper learning curve
- Used for procedures that require more detail like endodontics
- Darker field of view as there is a decrease in the amount of light coming through the lens as magnification becomes higher
– Test and Write
When comparing different loupes, test and check everything from your working distance, field of view, depth of field, declination angle and magnification, take note of what you liked and what felt most comfortable and what will prove to be the most effective when you’re working.
Using the loupe that you chose, look at the testing objects and select an area of tiny details that can only be seen with magnification. And also check for the most common signs of poor-quality loupes like low resolution, chromatic aberration and spherical aberration.
Resolution is defined as an optical system’s ability to form distinguishable images of objects separated by small distances, or to recognize fine detail. This refers to the clarity of the image, which is in turn determined by the quality of the optics. The better the optics the better the resolution. But this varies from brand to brand or type to type of loupes. So, the best way to determine which one is right for you is trying them on and seeing for yourself the clarity of the image in focus.
Chromatic Aberration refers to color distortion. Because each color has a different wavelength uncorrected optics causes the various wavelengths to focus at different points in space. The first color that generally comes out of focus is blue; when looking at black lines on white paper; poor quality loupes will display a blue haze just to the side of the black lines.
Spherical aberration refers to the flatness of the image. When viewed through loupes, an object that exhibits spherical aberrations would appear to be curved or spherical. The lines would not be straight.
Viewing Colorful or Complex Objects
Viewing colorful or complex objects such as anatomical models or the inside of your hand does not give you the opportunity to evaluate loupes for their true optical performance, as most people are not trained to see the differences on such complex images. A simple piece of graph paper, however, can reveal the difference between mediocre and high quality loupes.
Now here is where it gets a little bit complicated as this is the time to take other factors into consideration.
Comfort, Fit and Weight of the Loupe
remember that you will be wearing that loupe almost all day, every day! You’ll be wearing that loupe for long periods of time. For some not being able to notice or be bothered by the weight is a big factor in choosing their loupes. Find loupes that are lightweight, comfortable and fit you.
If You Use Glasses
If you use glasses with prescription lenses, it is important that you have the option of fitting your loupes frames with the correct prescription. Otherwise, the loupes will not perform according to specifications. The standard frames can easily be fitted with prescription lenses by your optician. Loupes are also available in a “clip-on” option, which can be clipped onto your regular glasses.
Interpupillary Distance / Pupillary Distance
The distance between the pupils of your two eyes is your interpupillary distance. For the sake of comfort when focusing, your loupes must fit your eyes. You optometrist can give you an exact measurement. It is best to get a loupe that is adjustable so that you can set your loupes to an interpupillary distance that suits you.
More tips on How to measure PD in the video.
Make sure that you can add a light source to it. According to a study there is a significant improvement in visual acuity when using magnification with a fibre-optic light source. Light intensityloupeof up to 30,000 lux is regarded as safe whilst minimizing glare. Much brighter LED lights are available, but they produce more glare, as the light is reflected from the surfaces of the teeth, and may not be safe for prolonged use. In addition to this, if loupe users do not have additional LED lighting, their pupils will dilate, reducing depth of field. LED lighting is mandatory with higher magnification and many experts consider it essential with any magnification. LUMADENT is an example of a light source preferred by many because it’s decently priced. It performs well and the battery lasts longer than some. The company even offers group discounts for students looking to buy them.
There are a lot to choose from ranging from lightweight to ultra-lightweight, from legend or iconic frames to sports frames. You can find one that suits your budget and preference.
Dental Loupes are available from $50 – $2000 and above. Believe it or not there are some people who use $50 dental loupes and they are happy with it; they find little difference with what they can clearly see with it compared to their dental loupes costing $1600. But of course, some people would opt for the expensive ones, as they feel it would be more reliable and durable. You get what you pay for is what they say. But again, with a lot to choose from you can always find what suits your budget.
This is another factor that some people take into consideration. Here are some brands I haven’t really tried but I have heard good things about:
The term “to each his own or personal preference” is definitely one of the things to remember when choosing dental loupes. As you do your research maybe online, you will find that it’s a daunting task that can sometimes become increasingly confusing as you go and research some more. A lot of people have different opinions about certain types or brands but these are only based on their own experiences which would definitely vary from person to person. What may work for others may not work for you. In conclusion, don’t be afraid to try out the dental loupes, test and check everything that needs to be tested. Hopefully this would help you in choosing the right dental loupes for you. Happy hunting!
- Magnifying Loupes In Modern Dental Practice : An Update by Teresa James et al
- The How To’s of Selecting Dental Loupes post by Stephen on Universal Medical site
- Surgical Loupes Defining Differences post on World Precision Instruments site