Editing Contact lens (section)

==Current research==
Contact lens sensors to monitor the ocular temperature have been demonstrated.<ref>{{Cite journal |vauthors=Moreddu R, Elsherif M, Butt H, Vigolo D, Yetisen AK |year=2019 |title=Contact lenses for continuous corneal temperature monitoring |url=http://pure-oai.bham.ac.uk/ws/files/60402992/c9ra00601j.pdf |journal=RSC Advances |volume=9 |issue=20 |pages=11433–11442 |bibcode=2019RSCAd...911433M |doi=10.1039/C9RA00601J |pmc=9063335 |pmid=35520262 |doi-access=free}}</ref> Monitoring [[intraocular pressure]] with contact lens sensors is another area of contact lens research.<ref>{{Cite journal |last=Baghban |first=R |last2=Talebnejad |first2=MR |last3=Meshksar |first3=A |last4=Heydari |first4=M |last5=Khalili |first5=MR |date=2 November 2023 |title=Recent advancements in nanomaterial-laden contact lenses for diagnosis and treatment of glaucoma, review and update. |journal=Journal of Nanobiotechnology |volume=21 |issue=1 |pages=402 |doi=10.1186/s12951-023-02166-w |pmc=10621182 |pmid=37919748 |doi-access=free}}</ref>

A large segment of current contact lens research is directed towards the treatment and prevention of conditions resulting from contact lens contamination and colonization by foreign organisms. Clinicians tend to agree that the most significant complication of contact lens wear is microbial [[keratitis]] and that the most predominant microbial pathogen is ''[[Pseudomonas aeruginosa]]''.<ref>Robertson, DM, Petroll, WM, Jester, JV & Cavanagh, HD: Current concepts: contact lens related Pseudomonas keratitis. ''Cont Lens Anterior Eye'', 30: 94–107, 2007.</ref> Other organisms are also major causative factors in bacterial keratitis associated with contact lens wear, although their prevalence varies across different locations. These include both the ''[[Staphylococcus]]'' species (''aureus'' and ''epidermidis'') and the ''[[Streptococcus]]'' species, among others.<ref>Sharma, S, Kunimoto, D, Rao, N, Garg, P & Rao, G: Trends in antibiotic resistance of corneal pathogens: Part II. An analysis of leading bacterial keratitis isolates, 1999.</ref><ref>{{Cite journal |vauthors=Verhelst D, Koppen C, Looveren JV, Meheus A, Tassignon M |year=2005 |title=Clinical, epidemiological and cost aspects of contact lens related infectious keratitis in Belgium: results of a seven-year retrospective study |journal=Bull Soc Belge Ophtalmol |volume=297 |issue=297 |pages=7–15 |pmid=16281729}}</ref> Microbial keratitis is a serious focal point of current research due to its potentially devastating effect on the eye, including severe vision loss.<ref>Burd EM, Ogawa GSH, Hyndiuk RA. Bacterial keratitis and conjunctivitis. In: Smolin G, Thoft RA, editors. '''The Cornea'''. ''Scientific Foundations and Clinical Practice''. 3rd ed. Boston: Little, Brown, & Co, 1994. p 115–67.</ref>

One specific research topic of interest is how microbes such as ''Pseudomonas aeruginosa'' invade the eye and cause infection. Although the pathogenesis of microbial keratitis is not well understood, many different factors have been investigated. One group of researchers showed that corneal hypoxia exacerbated ''Pseudomonas'' binding to the corneal epithelium, internalization of the microbes, and induction of the inflammatory response.<ref>{{Cite journal |vauthors=Zaidi T, Mowrey-McKee M, Pier GB |year=2004 |title=Hypoxia increases corneal cell expression of CFTR leading to increased Pseudomonas aeruginosa binding, internalization, and initiation of inflammation |journal=Invest Ophthalmol Vis Sci |volume=45 |issue=11 |pages=4066–74 |doi=10.1167/iovs.04-0627 |pmc=1317302 |pmid=15505057}}</ref> One way to alleviate [[Hypoxia (medical)|hypoxia]] is to increase the amount of oxygen transmitted to the cornea. Although silicone-hydrogel lenses almost eliminate hypoxia in patients due to their very high levels of oxygen transmissibility,<ref>Sweeney DF, Keay L, Jalbert I. Clinical performance of silicone hydrogel lenses. In Sweeney DF, ed. ''Silicone Hydrogels: The Rebirth of Continuous Wear Contact Lenses.'' Woburn, Ma: Butterworth Heinemann; 2000.</ref> they also seem to provide a more efficient platform for bacterial contamination and corneal infiltration than other conventional hydrogel soft contact lenses. One study showed that ''Pseudomonas aeruginosa'' and ''[[Staphylococcus epidermidis]]'' adhere much more strongly to unworn silicone hydrogel contact lenses than conventional hydrogel lenses and that adhesion of ''Pseudomonas aeruginosa'' was 20 times stronger than that of ''Staphylococcus epidermidis''.<ref>{{Cite journal |vauthors=Kodjikian L, Casoli-Bergeron E, Malet F, Janin-Manificat H, Freney J, Burillon C, Colin J, Steghens JP |year=2008 |title=Bacterial adhesion to conventional hydrogel and new silicone hydrogel contact lens materials |journal=Graefes Arch Clin Exp Ophthalmol |volume=246 |issue=2 |pages=267–73 |doi=10.1007/s00417-007-0703-5 |pmid=17987309 |s2cid=23218590}}</ref> This might partly explain why ''Pseudomonas'' infections are the most predominant. However, another study conducted with worn and unworn silicone and conventional hydrogel contact lenses showed that worn silicone contact lenses were less prone to ''Staphylococcus epidermidis'' colonization than conventional hydrogel lenses.<ref name="Santos2008">{{Cite journal |last=Santos |first=Lívia |last2=Rodrigues |first2=Diana |last3=Lira |first3=Madalena |last4=Real Oliveira |first4=M Elisabete C. D. |last5=Oliveira |first5=Rosário |last6=Vilar |first6=Eva Yebra-Pimente |last7=Azeredo |first7=Joana |date=July 2008 |title=Bacterial Adhesion to Worn Silicone Hydrogel Contact Lenses |journal=Optometry and Vision Science |volume=85 |issue=7 |pages=520–525 |doi=10.1097/OPX.0b013e31817c92f3 |pmid=18594343 |s2cid=10171270 |hdl-access=free |hdl=1822/8740}}</ref>

Besides bacterial adhesion and cleaning, micro and nano pollutants (biological and manmade) is an area of contact lens research that is growing. Small physical pollutants ranging from [[Microplastics|nanoplastics]] to fungi spores to plant pollen adhere to contact lens surfaces in high concentrations. It has been found that multipurpose solution and rubbing with fingers does not significantly clean the lenses. A group of researchers have suggested an alternative cleaning solution, PoPPR (polymer on polymer pollution removal).<ref>{{Cite journal |last=Burgener |first=Katherine |last2=Bhamla |first2=M. Saad |date=June 2021 |title=A polymer-based technique to remove pollutants from soft contact lenses |journal=Contact Lens and Anterior Eye |volume=44 |issue=3 |pages=101335 |arxiv=2005.08732 |doi=10.1016/j.clae.2020.05.004 |pmid=32444249 |s2cid=218673928}}</ref> This cleaning technique takes advantage of a soft and porous polymer to physically peel pollutants off of contact lenses.

Another important area of contact lens research deals with patient compliance. Compliance is a major issue<ref>{{Cite journal |last=Agarwal R.K. |year=1971 |title=A legally problematical but clinically interesting contact lens case |journal=The Contact Lens |volume=3 |issue=3 |page=13}}</ref> pertaining to the use of contact lenses because patient noncompliance often leads to contamination of the lens, storage case, or both.<ref>{{Cite journal |vauthors=Yung MS, Boost M, Cho P, Yap M |year=2007 |title=Microbial contamination of contact lenses and lens care accessories of soft contact lens wearers (university students) in Hong Kong |journal=Ophthalmic and Physiological Optics |volume=27 |issue=1 |pages=11–21 |doi=10.1111/j.1475-1313.2006.00427.x |pmid=17239186 |s2cid=6552480 |hdl-access=free |hdl=10397/22844}}</ref><ref>{{Cite journal |last=Midelfart J. |last2=Midelfart A. |last3=Bevanger L. |year=1996 |title=Microbial contamination of contact lens cases among medical students |journal=CLAO J |volume=22 |issue=1 |pages=21–24 |pmid=8835064}}</ref><ref>{{Cite journal |last=Gray T.B. |last2=Cursons R.T. |last3=Sherwan J.F. |last4=Rose P.R. |year=1995 |title=Acanthamoeba, bacterial, and fungal contamination of contact lens storage cases |journal=Br J Ophthalmol |volume=79 |issue=6 |pages=601–605 |doi=10.1136/bjo.79.6.601 |pmc=505174 |pmid=7626578}}</ref> However, careful users can extend the wear of lenses through proper handling: there is, unfortunately, no disinterested research on the issue of "compliance" or the length of time a user can safely wear a lens beyond its stated use. The introduction of multipurpose solutions and daily disposable lenses have helped to alleviate some of the problems observed from inadequate cleaning but new methods of combating microbial contamination are currently being developed. A [[silver]]-impregnated lens case has been developed which helps to eradicate any potentially contaminating microbes that come in contact with the lens case.<ref>{{Cite journal |vauthors=Amos CF, George MD |year=2006 |title=Clinical and laboratory testing of a silver-impregnated lens case |journal=Cont Lens Anterior Eye |volume=29 |issue=5 |pages=247–55 |doi=10.1016/j.clae.2006.09.007 |pmid=17084102}}</ref> Additionally, a number of [[antimicrobial]] agents are being developed that have been embedded into contact lenses themselves. Lenses with covalently attached [[selenium]] molecules have been shown to reduce bacterial colonization without adversely affecting the cornea of a rabbit eye<ref>{{Cite journal |vauthors=Mathews SM, Spallholz JE, Grimson MJ, Dubielzig RR, Gray T, Reid TW |year=2006 |title=Prevention of bacterial colonization of contact lenses with covalently attached selenium and effects on the rabbit cornea |journal=Cornea |volume=25 |issue=7 |pages=806–14 |doi=10.1097/01.ico.0000224636.57062.90 |pmid=17068458 |s2cid=25006245}}</ref> and [[octyl glucoside]] used as a lens surfactant significantly decreases bacterial adhesion.<ref>{{Cite journal |last=Santos L |last2=Rodrigues D |last3=Lira M |last4=Oliveira R |last5=Oliveira Real, ME |last6=Vilar EY |last7=Azeredo J |year=2007 |title=The effect of octylglucoside and sodium cholate in Staphylococcus epidermidis and Pseudomonas aeruginosa adhesion to soft contact lenses |journal=Optom Vis Sci |volume=84 |issue=5 |pages=429–34 |doi=10.1097/opx.0b013e318058a0cc |pmid=17502827 |s2cid=2509161 |hdl-access=free |hdl=1822/6663}}</ref> These compounds are of particular interest to contact lens manufacturers and prescribing optometrists because they do not require any patient compliance to effectively attenuate the effects of bacterial colonization.

One area of research is in the field of [[Bionic contact lens|bionic lenses]]. These are visual displays that include built-in electric circuits and [[light-emitting diodes]] and can harvest radio waves for their electric power. Bionic lenses can display information beamed from a mobile device overcoming the small display size problem. The technology involves embedding nano and microscale electronic devices in lenses. These lenses will also need to have an array of microlenses to focus the image so that it appears suspended in front of the wearer's eyes. The lens could also serve as a head-up display for pilots or gamers.<ref name="lc" />

Drug administration through contact lenses is also becoming an area of research. One application is a lens that releases anesthesia to the eye for post-surgery pain relief, especially after PRK ([[photorefractive keratectomy]]) in which the healing process takes several days. One experiment shows that silicone contact lenses that contain vitamin E deliver pain medication for up to seven days compared with less than two hours in usual lenses.<ref name="lc">{{Cite web |title=Contacts Release Anesthesia to Eyes of Post-Surgery Patients |url=http://www.lenscompare.co.uk/compare-contact-lenses-latest-research/ |url-status=dead |archive-url=https://archive.today/20130421013228/http://www.lenscompare.co.uk/compare-contact-lenses-latest-research/ |archive-date=21 April 2013 |access-date=4 April 2013 |df=dmy-all}}</ref>

Another study of the usage of contact lens is aimed to address the issue of [[macular degeneration]] (AMD or age-related macular degeneration). An international collaboration of researchers was able to develop a contact lens that can shift between magnified and normal vision. Previous solutions to AMD included bulky glasses or surgical implants. But the development of this new contact lens, which is made of polymethyl methacrylate, could offer an unobtrusive solution.<ref>{{Cite web |title=First Ever Switchable Telescopic Contact Lens |url=https://www.forbes.com/sites/meriameberboucha/2018/02/28/first-ever-switchable-telescopic-contact-lens/ |access-date=23 March 2018 |website=[[Forbes]]}}</ref>