Friday, December 6, 2019

Case Study-Contact Lenses-Free-Samples for Students-Myassignment

Question: Discuss about the Case Study of Contact Lenses. Answer: Earliest History of Contact Lens Technologies Their Efficacy in Correcting Vision Contact lenses are among the technologies which have transformed the modern global healthcare system. Since the 14th century, there have been efforts to create solutions to refraction errors on eyes which lead to short-sightedness, long-sightedness, and astigmatism. The development of contact lenses began way back in 1508 when Leonardo Da Vinci tried to wear a bowl of water on his head to aid in correcting vision (Fadel, 2017). This was his unsuccessful attempt to develop contact lenses as his device was impractical in altering vision. Later in 1636, Ren Descartes, a French scientist relied on Leonardos experiments to propose further ideas. He placed a liquid filled glass-tube directly in contact with the cornea (Vincent et al, 2016). His invention to some extent helped enhance vision except that blinking was impossible. For about two centuries later, there were no improvements on contact lenses designs. In the year 1801, Thomas Young who was an English Scientist used the ideas of Re n Descartes to come up with a pair of contact lenses. Young changed the design by Descartes where he reduced the glass tube size to exactly inch then stuck the lenses filled with water to his own eyeballs(Fadel, 2017). The device compromised the safety of the eye and seen as a ridiculous option. The device was out-rightly impractical and could not correct eye problems. The idea on the use of contact lenses to help in the correction refraction errors was never suggested until later in the year 1845(Toshida, 2008). In this period, Sir John Herschel, a physicist from England first hypothesized that if he took a mould of the eye cornea it would produce contact lenses to enable the correction of vision. Even so, the physicist did not have the right technology to enable him test this particular hypothesis. His theory however was only a speculation till around 100 years later. Improved Technologies on the Contact Lenses In the 1880s when novel glass production, shaping and cutting technologies emerged it was possible to develop thin lenses. Glass-made contact lens designs which fitted in the eye and allowed blinking for the wearer invented was independently by three different individuals. These included Dr Adolf Fick, Louis Girard and Eugene Cult(Vincent et al, 2016). Even so, the credit for this discovery has since gone to Dr Fick who was Swiss physician. Fick wrote A Contact Spectacle treatise describing the first ever contact lens that had refractive power that could improve vision. The first ever physical lens sample was created by F. A. Mueller, an artificial eye-maker in the year 1887(Toshida, 2008). These particular lenses were referred to scleral lenses since they covered the whole eye including the cornea. The lenses were slightly convex and allowed room for tears and dextrose solution. This solution was meant to create the refractive power which could correct vision. In the year 1888, Dr F ick was able to construct and fit the first ever successful contact lens. Even so, Ficks contact lenses created using heavy blown glass with an 1821mm diameter, were uncomfortable due to their weight(Guillon 2013). Even worse, the glass-made lenses covered an individuals whole exposed eye. The eyes unlike other organs in the body that get oxygenated by blood supplies, get oxygen from the air directly. Therefore covering the eyeballs with shields of glass as lenses essentially suffocates them. Use of scleral lenses developed by DR Fick according to Masoudi et al (2017) led to excruciating eye pain after several hours of using them. In spite of this problem, the glass-made scleral lenses remained the main contact lens forms for another 60 years later. In the late 1920s, there were advances in technology in the fields of anaesthesiology among other materials. These advances in technology enabled Sir John Herschels idea on developing corneal moulds to be tested. This was done in the year 1929, when the Hungarians Dr Dallos and Istvan Komromy developed a perfect technique of making moulds particularly from living eyes(Vincent et al, 2016). This development improved and proved Herschels postulations. This was the first time that creation of contact lenses which conformed to actual eye-shape was made possible. By 1930s there were plastics being produced and scientists in eye-care field opted to create contact lenses that were lightweight and transparent contact lenses(Guillon 2013). The emergence of unbreakable, malleable, easy to manufacture and scratch-resistant plastics led to yet another revolution in the industry driving glass contact lenses obsolete. Despite the advantages of the then new plastic contact lenses, they were scleral and therefore covered the whole eye and were wearable only for a few hours. In the year 1948, Kevin Touhy an optical technician from England was sanding down one plastic lens whose part fell off. This part was the section that was usually intended to cover the white of the eye ball. Instead of starting all over again, Kevin decided to try out the remaining smaller lens section (Masoudi et al, 2017). After smoothing its edges and popping it in his own eye, Kevin delightedly discovered that this particular lens could still work and also stayed in its place even during when blinking. Kevin Touhys happy accident brought forth the corneal contact lenses which are commonly used even today(Guillon 2013). The corneal lenses discovered then allowed the wearers to let the lenses stay longer in their eyes as the eye cells could somehow breathe. The corneal lenses were found to be more comfortable as compared to the earlier scleral lenses. The publicity of Touhys invention brought about rapid changes to corneal lenses. George Butterfield in the year 1950 postulated the need for curved corneal lenses contrary to the flat corneal lenses in the market then. In the late 1950s three other technicians including Frank Dickenson, John Neil and Wilhelm Sohnjes developed thinner lenses corneal lenses measuring about 0.20 mm. Thinner lenses measuring 0.10 m were later developed in 1960s(Toshida, 2008). Despite the numerous improvements done on corneal lenses they still hindered the flow of oxygen into the eyes. As a result, they could not be worn for a long time and/or overnight. The Modern Contact Lenses The efficacy of plastic corneal contact lenses and scleral lenses was still low in correcting vision problems. In the year 1958 when Otto Wichterle who was Czechoslovakian chemist discovered hydrogel, a soft and yet pliable plastic when it is wet that could be shaped appropriately and moulded to form contact lenses. Dr Robert Morrison from Pennsylvania USA being aware of Wichterles work recognized that hydrogel had the potential to make contact lenses(Diec et al, 2017).When Wichterle released his own patents for global use Dr Morrison being an optometrist set up a hydrogel manufacturing facility in his own lab to create soft contact lenses. In the early 1960s Bausch and Lomb after being granted access to this plastic they created a refined lens casting technique which could produce consistent surfaces of lenses. They also developed the mass production process of hydrogel contact lenses.In 1988, Ciba Vision introduced silicone hydrogels which offered extreme and high oxygen permeabili ty unlike the earlier versions of lenses (Diec et al, 2017).Over the later 25 years, soft and/or hard contact lensesperpetually improved particularly in regard to oxygen permeability, in order to enable eyes breathe. The best contact lenses today thus are breathable, comfortable and durable (Guillon 2013). It is thus important to appreciate the journey through which eye technology has taken since Da Vincis use of bowl of water to correct vision, to the modern flexible silicone discs which enhance vision more perfectly. References Diec, J., Tilia, D., Thomas, V. (2017). Comparison of Silicone Hydrogel and Hydrogel Daily Disposable Contact Lenses.Eye Contact Lens: Science Clinical Practice, 1. Ehrich, W. (1993). History of Contact Lenses.Eye Contact Lens: Science Clinical Practice,19(1), 80. Fadel, D. (2017). Modern scleral lenses: Mini versus large.Contact Lens And Anterior Eye,40(4), 200-207. Guillon, M. (2013). Are Silicone Hydrogel Contact Lenses More Comfortable Than Hydrogel Contact Lenses?.Eye Contact Lens: Science Clinical Practice,39(1), 85-91. Key, J. (2007). Development of Contact Lenses and Their Worldwide Use.Eye Contact Lens: Science Clinical Practice,33(Supplement), 343-345. Lira, M., Silva, R. (2017). Effect of Lens Care Systems on Silicone Hydrogel Contact Lens Hydrophobicity.Eye Contact Lens: Science Clinical Practice,43(2), 89-94. Masoudi, S., Zhao, Z., Stapleton, F., Willcox, M. (2017). Contact LensInduced Discomfort and Inflammatory Mediator Changes in Tears.Eye Contact Lens: Science Clinical Practice,43(1), 40-45. Toshida, H. (2008). Bifocal contact lenses: History, types, characteristics, and actual state and problems.Clinical Ophthalmology, 869. Vincent, S., Alonso-Caneiro, D., Collins, M. (2016). Evidence on scleral contact lenses and intraocular pressure.Clinical And Experimental Optometry,100(1), 87-88.

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