GP lenses are still a good choice for light and moderate keratoconus
05 January 2022
3 minutes to read
Biography / Disclosures
Gloria B Chiu, OD, FAAO, FSLS, is Associate Professor of Clinical Ophthalmology at USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, Los Angeles.
Disclosures: Chiu claims to be a consultant for Glaukos and receives honoraria from Acculens and BostonSight.
Most people with keratoconus use specialized contact lenses for better corrected vision.
While some with a mild presentation may work well with soft contact lenses, many with moderate to advanced keratoconus may require custom lenses made from gas permeable plastic (GP).
The field of specialty contact lenses has grown considerably over the past decade, with particular attention paid to scleral lenses. The rate of scleral lens fitting by ophthalmologists has been increasing since 2011 (Woods et al.), And scientific research on scleral lenses has also increased over the same period (Povedano-Montero et al.).
Gloria B. Chiu
While few articles were written on scleral lenses until 2007, there has been a steady increase in publications since then (Efron et al.). A recent study in 2020 evaluating 86 subjects over a 5-year period even affirmed the safety and long-term effectiveness of scleral lenses in visual rehabilitation of patients with keratoconus (Fuller et al.).
It’s easy to see why scleral lenses have become a popular contact lens option for keratoconus patients; they offer good comfort, stability and vision. These lenses pop over the cornea and do not rub on the ectatic corneal tissue, which also happens to be highly innervated.
The larger lens diameter also decreases movement on the ocular surface and limits friction with the inner eyelids; Customization of lens design with trial lenses, profilometry, and impression molding techniques can lead to fine adjustments. In addition, with the ability to incorporate front surface astigmatic correction, off-center optics, and higher order aberration control, vision correction can be excellent.
So why would anyone still prescribe GP contact lenses? These lenses rub against sensitive corneal tissue, frequently off-center the cornea, aid in corneal molding, pop out easily with extreme eye movements, and look like broken glass when dust enters the eyes.
Simply put, GP lenses work great for the right patient. In patients with mild to moderate keratoconus, GP lenses should be presented as an option. A well-centered or tethered fit to the cover, with proper alignment and movement, can provide excellent comfort and excellent vision.
These lenses are smaller and easier to apply and remove. Unlike scleral lenses which require a saline liquid to fill the reservoir and careful balance for application, GP lenses can be placed directly on the cornea with a finger. The cost of these lenses and their maintenance is considerably less than scleral lenses and may be more affordable for some patients.
While scleral lenses may seem like a “sexier” option, there are increasing reports of problems and complications with scleral lenses, including conjunctival prolapse, epithelial swelling, midday fogging, limbic support and hypoxia. (Walker et al.). Training time for handling and caring for lenses can be long in the office, and specialized cleaning and saline products can be difficult to find.
A study published in 2020 assessed satisfaction and burden of care in patients with keratoconus with contact or scleral lenses (Shorter et al.). The results of the study based on an electronic survey found that scleral lens wearers were more satisfied with vision and comfort, but both groups reported problems with blurred or hazy vision and contact lens discomfort. .
Although GP wearers reported more problems with movement or lens loss, they had less difficulty with halos and lens handling compared to scleral lens wearers. GP wearers also reported less annual out-of-pocket expenses compared to scleral lens wearers.
No contact lens modality is perfect, and each type has its pros and cons. It is our job as optometrists to determine the best modality for each patient, taking into account disease presentation, profession and lifestyle.
Additionally, we must also remember to watch for progressive keratoconus and consider corneal crosslinking when indicated, as good acuity in specialized contact lenses can mask progressive signs.
While GP lenses haven’t been in the spotlight recently, that doesn’t mean they aren’t a good option for the right keratoconus patient.
- Efron N, et al. Front Eye Cont lens. 2021; doi: 10.1016 / j.clae.2021.101447.
- Fuller DG, et al. Optom Vis Sci. 2020; doi: 10.1097 / OPX.0000000000001578.
- Lim L, et al. Eyeil (London). 2020; doi: 10.1038 / s41433-020-1065-z
- Moschos MM, et al. Open Ophthalmol J. 2017; doi: 10.2174 / 1874364101711010241.
- Ortiz-Toquero S, et al. Curr Opin Ophthalmol. 2021; doi: 10.1097 / ICU.00000000000000728.
- Povedano-Montero FJ, et al. Eye contact lens. 2018; doi: 10.1097 / ICL.0000000000000478.
- Saraç Ö, et al. Front Eye Cont lens. 2019; doi: 10.1016 / j.clae.2019.02.013.
- Schornack MM. Eye contact lens. 2015; doi: 10.1097 / ICL.00000000000000083.
- Shorter E, et al. Optom Vis Sci. 2020; doi: 10.1097 / OPX.0000000000001565.
- Walker MK, et al. Front Eye Cont lens. 2016; doi: 10.1016 / j.clae.2015.08.003.
- Woods CA, et al. Clin Exp Opt. 2020; doi: 10.1111 / cxo.13105.
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gLoria B Chiu, OD, FAAO, FSLS, is Associate Professor of Clinical Ophthalmology at USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, Los Angeles.