Impact of manufacturing technology and material composition on the clinical performance of hydrogel lenses
Maldonado-Codina, Carole & Efron, Nathan (2004) Impact of manufacturing technology and material composition on the clinical performance of hydrogel lenses. Optometry And Vision Science, 81(6), pp. 443-454.
PURPOSE: To establish the clinical impact of three different methods of manufacture used to produce soft contact lenses. METHODS: Clinical performance of five lens types was investigated by undertaking a prospective, double-masked, randomized, crossover study. Three of the lenses were made from poly(hydroxyethyl methacrylate) (pHEMA) by three different manufacturing processes (lathing, spin casting, and cast molding), and the remaining two lenses were cast molded from different materials-hydroxyethyl methacrylate/methacrylic acid and hydroxyethyl methacrylate/glycerol methacrylate (HEMA/GMA). All lenses were specially fabricated for this work at the same manufacturing plant. Thirty-four soft contact lens wearers wore each lens for 1 month on a daily-wear basis. Several clinical variables, such as ocular response, visual acuity, lens fitting, prelens tear film, lens surface dehydration, subjective response, and protein deposition, were measured. RESULTS: In general, the spun-cast pHEMA lens performed inferiorly compared with the other pHEMA lenses. This lens induced significantly more limbal and conjunctival hyperemia than the cast-molded lens and provided poorer low contrast visual acuity (LCVA) than the other two lenses. It dehydrated more and had the least on-eye movement. However, the spun-cast lens deposited the least protein of the pHEMA lenses. In general, the HEMA/GMA lens performed inferiorly compared with the other cast-molded lenses. LCVA was worse with this lens, and subjective responses showed that this lens was thought to give the worst visual performance of the cast-molded lenses. It was also thought to be the most difficult lens to handle. Significantly more breakages occurred with this lens than any other. CONCLUSIONS: Overall, this work has shown that manufacturing method and material composition have a fundamental effect on many clinical properties of a lens. Therefore, method of manufacture is also an important consideration in the overall production of a soft lens.
Impact and interest:
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|Item Type:||Journal Article|
|Additional Information:||The contents of this journal can be freely accessed online via the journal's web page (see hypertext link) 12 months after publication. For more information, please refer to the journal's website or contact the author.|
|Keywords:||clinical performance, contact lens, hydrogel, manufacture, polymerization|
|Subjects:||Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)|
Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300) > Optical Technology (111302)
|Divisions:||Current > Research Centres > Centre for Health Research|
Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
|Copyright Owner:||Copyright 2004 Lippincott Williams & Wilkins|
|Deposited On:||28 Nov 2007|
|Last Modified:||29 Feb 2012 23:29|
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