From the Guidelines
Contact lenses directly interface with the cornea, providing enhanced visual acuity and an unobstructed field of view by correcting refractive errors such as myopia, hyperopia, and astigmatism. They come in various types, including soft lenses (daily disposable, bi-weekly, or monthly), rigid gas permeable lenses, and specialty lenses like toric (for astigmatism) or multifocal designs 1. The choice of material is a patient and practitioner preference; however, for patients at risk of hypoxia-related complications, silicone hydrogel (SiHy) material should be considered 1.
Key Considerations
- Daily disposable lenses are the type of soft lens that is least likely to be associated with infectious or inflammatory complications 1.
- Rigid gas-permeable and hybrid contact lenses can correct high astigmatic errors effectively 1.
- Custom-designed soft toric contact lenses provide another means to correct high astigmatic refractive errors, offering good centration when properly fitted, a flexible wear schedule, and improved comfort in some patients 1.
- Rigid gas-permeable scleral lenses are an option for the correction of high and/or irregular astigmatism, particularly if combined with anisometropia 1.
Proper Care and Use
Proper care is essential, including regular cleaning for reusable lenses, adhering to replacement schedules, and never sleeping in lenses unless specifically designed for extended wear 1. Users should have regular eye exams, as improper use can lead to complications like infections or corneal damage. Additionally, contact lenses may be able to improve visual function by creating a smoother and more regular refractive surface, particularly in cases of corneal edema or opacification 1.
Types of Contact Lenses
- Soft hydrogel, rigid gas-permeable, or silicone hydrogel contact lenses can correct spherical refractive errors 1.
- Soft toric contact lenses or rigid gas-permeable contact lenses can correct low to moderate astigmatism 1.
- Daily disposable wear of contact lenses causes less damage to the ocular surface and less increase in proinflammatory cytokine levels compared with the use of reusable lenses 1.
From the Research
Contact Lenses and Visual Acuity
- Contact lenses directly interface with the cornea, providing enhanced visual acuity and an unobstructed field of view 2.
- Studies have shown that contact lenses do not impair visual performance compared to spectacle lenses for the majority of myopes 2.
- In fact, contact lenses can provide better visual performance for myopes, with no statistically significant difference in central and peripheral visual performance between contact lenses and spectacles 2.
Types of Contact Lenses
- Silicone hydrogel contact lenses have been shown to improve epithelial healing and reduce pain in persistent epithelial defects, after trauma or surgery, and in corneal dystrophies 3.
- Hydrogel and silicone hydrogel soft contact lenses have been compared in terms of comfort and safety, with no clear difference in comfort between materials, although results were of low certainty 4.
- Different optical designs of contact lenses, such as single-vision, progressive, and bifocal lenses, can influence binocular vision and visual behavior among young adults 5.
Visual Performance and Contact Lenses
- Contact lenses can affect accommodative lag, negative relative accommodation, and distant and near vergence, but can also improve vergence facilities, accommodative facilities, and visual behavioral performance 5.
- Progressive and bifocal contact lenses can relax accommodation, reduce the lag of accommodation, and improve visual behavioral performance, although they may also cause complaints about halos at night or double vision 5.
- The choice of contact lens material and design can depend on individual factors, such as the type of refractive error, corneal health, and personal preference 3, 4, 5.