RGPs are commonly acknowledged that they provide clearer vision than soft lenses, especially for astigmatism. However, most of the traditional RGPs have a slight gap between the lens edge and the eye surface, in order to allow more oxygen in tears during blinking. It is still this special design which may make people uncomfortable, especially for those with irregular eye surface shapes. In this case, customized RGPs are designed to tackle this dilemma, which have different measurements and lens designs.
For conventional RGPs, an instrument called keratometer is used to measure the cornea’s curvature. And the curvature of conventional RGPs has three elements: the curve of the steepest meridian, the curve of the flattest meridian and the orientation of the flattest meridian. These measurements help doctors or manufacturers determine the curves of RGPs’ back surface. Conventional RGPs always have a central curve and two periphery flatter curves.
Custom RGPs require more complex eye measurements and lens designs. Unlike conventional RGPs, they need the eye’s several thousand points’ curvatures data obtained by a corneal topographer. All these curves are used to form multi-curved lenses, which conform more closely to cornea surface and create smoother point-to-point curvature changes. These measurements and lens designs provide more comfortable fitting for special eyes and also permit more oxygen to directly reach the eyes.
Custom contact lenses offer a change for everyone who has been disappointed by traditional RGPs. Custom RGPs are particularly useful for people with keratoconus and irregular corneal curvature, caused by eye injuries, failed LASIK or just born with that. Another type of custom RGPs are multifocal RGPs, which are created for presbyopia. In conclusion, custom RGPs provide a more effective way to correct myopia and astigmatism.
Soft contacts are also available in custom types, even if they are not as competitive as custom RGPs. But custom soft contacts do offer a better solution for high level astigmatism than conventional toric contacts, which are effective only for astigmatism below 2.5 diopters. Custom toric lenses offer higher powers as well as slighter increments.
Custom contact lenses may be your choice once you have failed in fitting some conventional contacts or you just want to make a change. Requiring additional time and skills, custom contacts cost about two times more than common contact lenses. You may contact your eye doctor for detailed information.
this article is come from:http://vision.firmoo.com/contact-lenses/contact-lenses-for-personalized-needs.html
(ArticlesBase SC #1340934)
Vision Library is the information source in area of vision care, including eyeglasses, sunglasses, contact lenses, sports protective eyewear, vision error and diseases, vision surgery, ageing and kid’s vision etc., solely sponsored by Firmoo.com, an emerging online optical store.