Optics / Orascoptic Loupe Systems / What is really important?
Ausdruck der Seite: www.sigmadental.de/en/optik/orascoptic_lupensysteme/was_ist_wichtig.php - 16.12.2018 - 18:28:28

What is the most important aspect?

 

Discover the lightness of seeing!


The use of a loupe system in a dental practice adds significantly to your diagnostic and therapeutic options.

But which system is right for you? And how important in this context are factors such as:

• Resolution        • Field of view        • Field depth       • Ergonomics        • Magnification

In the following you will find a few explanations that should certainly help you to find the right loupe system for your needs:


What does "magnification" actually mean?
Definition: the ratio between retinal image sizes with and without a magnification system.

The given magnification depends on various factors that are defined by the loupe manufacturer. To date, there is unfortunately no uniform standard for defining levels of magnification. Because of this, magnification numbers alone are not directly comparable for the different systems.

Although higher magnifications allow the operator to recognise finer structures, the resolution of magnified structures also presents a problem. In this context only top-rate optical systems can deliver a broader, larger view which rather than being blurred is razor sharp.



What does "Resolution" refer to?

Definition: The smallest distance between two points that will allow them to be perceived separately.

A high quality lens system is characterised by perfectly matched, high quality components that are manufactured with great care. This allows outstanding resolution to be achieved and therefore faithful reproduction of even the smallest of structures. The image resolution depends not only on a higher magnification, but also on the optical quality of the lenses.

When these conditions are met, the target image appears as very sharp and clear in the entire field of view without any distortions or chromatic aberrations. By using high-quality multi-lens systems, image errors can be eliminated for the most part. Aberrations may arise e.g. in the form of marginal blurring or chromatic aberration.



What does "Field of view" refer to?
Definition: The size of a visible field related to a particular working distance

A large field of view provides an optimal overview of the treatment area. With increasing magnification, the field of view becomes smaller. It is therefore always important to carefully consider which applications the system is to be used for before buying.

By the way: Different applications can require different fields of view.





What does "Field depth" refer to?
Definition: The field depth refers to the spatial depth over which the object being visualised is in sharp focus.

Each lens system has a certain working distance for which the field depth is calculated. For certain systems the working distance can be given while for others the magnification describes the distance. A large field depth allows the observer to always have a clear picture, even if the distance to the object is changed. The resulting freedom of movement does not merely relieve the eyes, but it also relieves the entire neck.

Only through precisely crafted and matched lenses and telescopes can a large field depth be achieved!




What does "Ergonomics" actually refer to?
Definition: A doctrine of human occupational sciences which deals with the optimal adaptation of working to the characteristics and capabilities of the people doing that work.

A lightweight and good balance is what really provides comfort for a complete loupe system. For new users in particular the weight can be one of the most important criteria when making a decision. In this context, it is especially appropriate to know that as magnification increases the telescope also becomes heavier so that the total weight also increases somewhat. However, in addition to the weight of the dental loupes, the angle of the built-in telescope and the resulting inclination of the head also play very important roles.


In combination with the individual working distance, the optimum inclination angle also helps to provide comfortable and concentrated working over a long period. By adopting such a correct ergonomic posture, complaints in the neck and back area can also be prevented.


You should therefore always decide for a model that offers the correct working angle for you or where the ergonomic inclination angle required in each case can be selected.


Loupe types and levels of magnification
Unfortunately, some loupe manufacturers still cling to the now outdated tradition that the magnification level is the most important feature. In addition, manufacturers also classify their products according to their self-assigned magnification levels. This is more irritating than helpful when choosing the right magnification level.

The magnification details serve mainly for orientation and at most only allow a classification based on the purpose for which a loupe is needed. A more realistic approach would be to classify the products into groups, as is the case in the automotive industry (e.g. small cars, medium-range and luxury cars). It needs to be a simple system that allows both the experienced user as well as uninitiated parties a clear understanding of the choices available.


Options for classification:


Class I
Single lens systems (such as reading glasses at low magnifications)

  Class II
2,0 – 2,9 power magnification, usually Galileian systems, consisting of a plus lens as an objective and a minus lens an an telescope               
  Class III
Between 3,0 – 3,9 power magnification*

Class IV
Between 4,0 – 4,9 power magnification

The last two classes are usually prismatic lenses (according to Kepler), named after the prism between the positive refracting telescope and objective, which provides the observer with a non-inverted image.

* Some Class III loupes are Galileian systems with a narrow field of view.


Diopters or magnification?
Some manufacturers confuse the rule of thumb that relates the diopter with the magnification. Technical aspects surrounding the lens can be difficult to understand and misleading.

A diopter is an optometric unit that represents the reciprocal of the focal length of a single lens in meters **. The diopter corresponds to the refractive power (the ability to bend light rays) and is applicable only to single lenses.

In dentistry, the dental loupe systems used feature several positive and negative lenses. Since prescription corrective lenses can also be used, the actual diopter (or refractive power) of a loupe is not directly associated with its magnifying power.


Conclusion

Using a loupe system the eyes are relieved and the body posture is relaxed. This reduces (later ensuing) health problems in the neck, back and shoulders of the users of such systems.

When buying a loupe system, you should consider the following:

  • A larger image does not always mean a better view!
  • In the first place one should always consider the resolution and the field of view, and not just the magnification! The best loupe systems create a synergy between all the individual components!
  • Always choose a model that provides a correct working angle!

** General Ophthalmology, Tenth Edition, 1989


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