Occupational progressive lenses (OPLs) are a family of lenses with different designs. The OPLs' design principle revolves around power optics, and they are chiefly intended to aid the user to satisfy both the near and intermediate viewing needs for example work involving the use of powerful computers. Usually, OPLs are designed in such a way that the bottom part of the lens is used for the near power while the upper portion is fabricated for intermediate distance usage (Kazuma, 2017).
A progressive lens has four major parts
Distance vision: this is the region that the wearer uses when they are in a relaxed mode
Intermediate view: this is the broad area referred to as the corridor. Intermediate vision is used when one is doing desk jobs like using a computer positioned slightly ahead of them (Odaira & Izawa, 2017).
Near vision: When one is concentrating on items parallel to a desk, they use the near vision region.
Blurred region: this refers to the distorted area as a result of condensing several prescriptions into one piece of lens. Wavy or blurred vision characterizes the blurred region. Ideally, a progressive lens should have less of this region and more of the intermediate region (Vidal, Heredia, Piers and Weeber, 2017)
Comparison of Various Designs of Progressive Power Lenses.
Zeiss Progressive Lenses
Zeiss Progressive Lenses are designed to offer an optimal vision for near and far zones. The lenses are targeted to perfectly fit the wearer ensuring greater tolerance, faster adaptation, and clear vision. The lens design is such that the near, intermediate and far distance zones are all integrated into one piece of a lens with a smooth transition (Jaschinski et al. 2015).
The Zeiss progressive lens provides the wearer with a clear vision whenever there is a tilting motion by the user. In the event of movement, the transition of the optical distances is smooth with zero incidences of jumping and blurred images (Barbero & Portilla, 2016)
The near optical zone of these progressive lenses is optimized for use with smartphones and tablets. Also, book reading is well catered for by these lenses. The progressive lenses from Zeiss take into consideration the rapid eye movement when one is using digital devices.
Nikon Progressive Lenses.
Nikon progressive lenses come in various designs with the aim of delivering a robust optical functionality, and better aesthetics all integrated into on lens. The following are the different categories of Nikon Progressive Lenses Designs.
Firstly, there is SEAMAX POWER which has the most personalized vision according to patient's unique personal data. The lenses take into consideration near vision working distance, pupil distance, and far vision power. The lenses are designed to eliminate distortion on the entire lens surface (Jaschinski et al. 2015). This progressive lens gives smooth far to near vision alongside minimal blurriness. Secondly, Dual Filter Progressive Lenses from Nikon boasts of sharper and broader vision for fast adaptation through the reduction of aberrations thus guaranteeing visual clarity and sharpness (Jaschinski, 2008).Lastly, the DIGLIFE lens is designed for optimum far and near vision regions. They have an improved vision area thus allowing easier usage of your digital devices.
ESSILOR Progressive Lenses
CRIZAL lenses from ESSILOR are engineered to offer best services for the eyes through clear vision. The lenses are suited to protect against glare, scratches, dust, water and ultra-violet light.
CRIZAL FORTE coating is useful for extra strength against scratching while CRIZAL PREVENCIA offers the best protection against UV. VALILUX progressive lenses are multifocal designs best suited for sharp, natural vision and smooth transition at any required distance (Jaschinski, 2008).
Superior polarized prescription sun lenses from ESSILOR provides maximum UV protection. They also offer resistance to exceptional scratch and eliminate glare for sharp colors.
EYEZEN help to reduce strain from viewing digital devices and daily works. They are designed to keep eyes comfortable and relaxed. More so they allow beneficial light to pass through while deflecting dangerous UV lights.
Progressive Lenses Prescription Numbers
The prescription numbers for progressive lenses may include SPH, CYL, ADD, and Pupillary Distance (PD). Additionally, the prescription may include O.D, O.S, and O.U. These numbers are explained below.
SPH (Sphere)-indicates the eyeglass prescription power for vision correction
CYL (Cylinder)-indicates astigmatism and the lens strength needed to correct it.
Axis-describes the degree and direction of astigmatism
ADD- refers to add magnifying power in the lower part of multi-focal lens.it is used to correct presbyopia.
O.D-Refers to Oculus Dexter meaning right eye.
O.S-Refers Oculus Sinister meaning left eye
O.U-Refers Oculus Uterque, meaning both eyes.
The further from zero the numbers are the more the correction is required (Guillot, Videmann & Rousseau, 2015).
+ means that the patient is farsighted (they have challenge focusing on very near things1)
-indicates that the patient is nearsighted thus they struggle to focus on objects that are far away
Progressive Lenses Prescription Charts
SPHERE CYLINDER AXIS ADD
O.D +4.20 +2.45 080 +1.00
O.S 4.00 +1.40 075 +1.00
Discuss the different fitting criteria for progressive power lens
When selecting the best progressive lens to fit in the patient's eye and offer the best vision, the opticians considers patient's occupation, patient's description, leisure activities and the duration of wearing the lenses. Benefits of the progressive lens are achieved when the glasses are well fixed and adjusted to fit the frame and the face (Tranvouez, Poulain, Marin & Calixte, 2017).
Creation of exceptional pair of glass requires the use of cutting edge digital dispensing technology which offers accurate measuring capabilities.
The two measurements taken by the optician before ordering lenses include; Pupillary Distance which is the distance between the pupils and Fitting Height which is the distance from the center of the pupil to the bottom of the lens for every eye (Forkel et al. 2017).
Frame choice plays a crucial role in the lenses. It is one of the foremost consideration when purchasing progressive lenses since they work differently on different sized frames. Frame measurements on the patient's eye begin with a mark on the lens at the center of the pupil whereby a horizontal line is drawn on each lens.
The appropriate height is measured depending on the progressive lens used which then directs the optician to measure the fitting height from the lenses deepest point up to the pupil centre.
The second measurement is done on the Pupillary Distance. Here, the optician takes a monocular measure and use the reflex pupillometer to ensure the exact size is taken. The pupillometer is switched into the nearest settings, and the closest PD is recorded.
Once the accurate measurements have been taken, the lens is placed over the layout chart to verify whether it will fit the frames. Different frames are selected until the most suitable that fits the lenses well is identified.
When fitting the glasses on the face, one is supposed to maintain the natural posture since tilting of the head leads to errors in the Fitting Height measurements (Mcclimans & Guerra, 2017).
Link progressive power lens designs to specific occupational requirements
A progressive lens is designed depending on the job that an individual performs. It focuses on how professional member performs various activities. Lens for office purpose is different from those worn in the field. They can be general purpose or computer vision lens. General use is designed for individuals who have a problem differentiating infinity and near reading distances (Jaschinski et al.2015).
Single Vision Lenses are suitable for reading distant objects and driving.
Occupational lenses are best worn for VDU and office work.
Bifocal lenses are designed to be used for viewing near visions and distance.
Trifocals lenses are useful for distance, intermediate and near viewing like computering.
Varifocal lenses are perfect for people who require different prescriptions for distance and reading vision. On the other hand, a standard reading lens is suitable for people who need to view near objects only. Additionally, people who especially those working in the office combine multiple near and mid-range tasks like presentations and holding meetings.
A progressive vocational lens is useful to people who require a depth of vision. Office users, especially in conferences and meetings, use them to see across the vision due to the provision of a broader area for near and intermediate sights (Guillo et al. 2015).
Occupational lenses help us perform various duties in the different work environment. The lenses are designed to serve multiple occupations based on the vision distance required. Lenses for computer users who need high visibility for near objects/ screen are created differently from those of drivers. An occupational lens especially Zeiss is useful for various individuals as they help reduce dizziness, headache and ocular strain. Before purchasing any lens, an individual need to first determine the purpose of the lens, the technical task, and the users preference
Barbero, S. and Portilla, J., 2016. The relationship between dioptric power and magnification in progressive addition lenses. Ophthalmic and Physiological Optics, 36(4), pp.421-427.
Blum, R.D., Kokonaski, W., Iyer, V.S., Haddock, J.N. and Mattison-Shupnick, M., Mitsui Chemicals Inc, 2015. Multifocal lens having a progressive optical power region and a discontinuity. U.S. Patent 9,033,494.
Forkel, J., Reiniger, J.L., Muschielok, A., Welk, A., Seidemann, A. and Baumbach, P., 2017. Personalized Progressive Addition Lenses: Correlation between Performance and Design. Optometry and Vision Science, 94(2), pp.208-218.
Guillot, M., Videmann, A. and Rousseau, B., Essilor International Cie Generale d'Optique, 2015. Spectacle lens providing ophthalmic vision and an additional vision. U.S. Patent 9,223,147.
Guisasola, L., Tresserras, R., Rius, A. and Purti, E., 2014. Visual correction and occupational social class. Optometry and Vision Science, 91(4), pp.464-471.
Jaschinski, W., 2008. Low monitor positions when using general purpose progressive lenses at computer work. German. Zbl Arbeitsmed, 58, pp.172-180.
Jaschinski, W., Konig, M., Mekontso, T.M., Ohlendorf, A. and Welscher, M., 2015. Comparison of progressive addition lenses for general purpose and for computer vision: an office field study. Clinical and Experimental Optometry, 98(3), pp.234-243.
Kazuma, K.O.Z.U., HOYA LENS THAILAND Ltd, 2017. Progressive addition lens, design method and manufacturing method therefor, and progressive addition lens manufacturing system. U.S. Patent Application 15/301,214.
Odaira, T. and Izawa, Y., HOYA LENS THAILAND Ltd, 2017. Progressive power lens group. U.S. Patent Application 15/513,366.
Mcclimans, P.A. and Guerra, J., ESSILOR INTERNATIONAL, 2017. LENS HOLDER AND METHOD OF USE. U.S. Patent Application 15/540,234.
Schilling, T., Ohlendorf, A., Varnas, S.R. and Wahl, S., 2017. Peripheral Design of Progressive Addition Lenses and the Lag of Accommodation in Myopes. Investigative ophthalmology & visual science, 58(9), pp.3319-3324.
Tranvouez, D., Poulain, I., Marin, G. and Calixte, L., Essilor International Cie Generale d'Optique, 2017. Method for determining a lens design of an optical lens adapted to a wearer. U.S. Patent Application 15/517,379.
Vidal, C.C., Heredia, A.A., Piers, P.A. an...
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