Corneal GP Lenses

Is your vision when wearing glasses or soft contact lenses not as crisp and clear as you want it to be? Corneal gas permeable (GP) lenses may be for you. Corneal GPs are durable small diameter lenses that are made of materials that easily allow oxygen to pass through them. Oxygen is important for the tissue under the contact lens, the cornea, to remain healthy. Corneal GPs offer expanded, and more customizable shapes and strengths compared to glasses and soft contact lenses, allowing them to correct high amounts of myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia. Additionally, they offer superior correction for astigmatism compared to glasses and soft contact lenses because of their resistance to lens bending, or flexure, as well as their ability to create a tear film behind the lens that can compensate for irregularities on the front surface of the eye.1

Aphakia

Congenital cataracts are the most common treatable blinding eye disease in children. They account for an estimated 10% of the world’s childhood blindness with an estimated prevalence of 4.24 per 10,000 children. In cases when congenital cataracts are sight threatening, surgery at an early age is the first step to acquiring good vision. Due to significant eye growth that occurs during childhood, those younger than 2 years old do not undergo an intraocular lens implantation at the time of surgery due to an increased risk of complications. This leaves children aphakic, without a lens, and results in a high hyperopic (farsighted) prescription. Therefore, contact lenses are the first choice to ensure proper visual development as well as visual rehabilitation. Corneal GPs can provide good visual rehabilitation for children with aphakia, allowing intraocular lens implantation to be postponed.2,3

Irregular Cornea

Ectasia

Corneal ectasias effect both eyes and cause thinning of the cornea that gets worse over time. . Keratoconus is the most common corneal ectasia with an estimated prevalence of 1 in 2000 based on registry data in the United States from 1935 to 1982.4 More recent data suggests that the prevalence is much higher, estimated to be 1 in 334.5 Patients with mild disease may be able to achieve adequate vision in glasses or soft contact lenses.As the disease progresses, visual acuity is typically reduced due to corneal steepening, thinning, and scarring inducing irregular astigmatism. Symptoms patients may have is reduced vision, distortion, glare, light sensitivity, and halos. Corneal GP lenses can be used to mask corneal irregularities from keratoconus and allow for adequate visual function.4.

Corneal Transplant

Corneal transplants are useful to alleviate signs and symptoms of corneal disease; however, specialty contact lenses are required in 63-77% of patients to provide the best possible visual acuity.1,6 Despite advances in surgical techniques, postoperative astigmatism remains the primary cause of suboptimal visual acuity after corneal transplants. The most frequent cause of reduced spectacle-corrected visual acuity after corneal transplant is the irregularity of the anterior corneal surface.7 Therefore, after corneal shape has stabilized, care can be coordinated with the performing surgeon to focus on visual rehabilitation. Due to lens rigidity and the tear layer formed behind a corneal GP, anterior corneal irregularities can be masked, thereby improving visual acuity with this lens modality.7

Corneal Scar

Corneal scars can be the result of trauma, infections, or other ocular diseases. Once the underlying cause of corneal scarring is identified and treated, the resulting scar may prevent glasses and soft contact lenses from providing clear and comfortable vision.. Reduced visual acuity occurs due to induced astigmatism or encroachment of the scar over the visual axis.8 This can result in significant loss of visual function due to diminished visual acuity and glare.9 In cases such as these, corneal GPs can be essential in providing improved visual quality by creating a new smooth refractive surface and using the tear lens underneath the lens to neutralize any front surface irregularities that remain10.

Corneal GPs are an ideal nonsurgical alternative to provide improved vision for those with irregular corneas.8 Eye Care providers mayuse corneal mapping tools such as topography or tomography to guide their fitting process and to ensure optimal patient success. Additionally, the treatment of irregular corneas requires attentive care and a multidisciplinary approach from several eyecare and healthcare providers. For further information and to learn if corneal GPs can help provide you with improved vision, please contact your local eye care professional.

Piggyback

If you have attempted corneal GP lens wear and have been unable to achieve a comfortable fit with stable vision or if you are having trouble adapting to your corneal GPs, a piggyback lens system may be right for you. The piggyback lens system is a combination of a corneal GP with good optical correction and a soft contact lens underneath which acts as a cushion., This system reduces mechanical stress on the cornea, thereby increasing comfort and reducing damage to the corneal surface.11 Piggyback lens systems may provide improved comfort and fit compared to corneal GP’s alone as well as improved vision compared to soft lenses alone. If you believe a piggyback lens system is the lens modality for you, please contact your eyecare provider for more information.

Contributed by: Matthew McGee, OD, FAAO

References

1. Wietharn BE, Driebe WT Jr. Fitting contact lenses for visual rehabilitation after penetrating keratoplasty. Eye Contact Lens. 2004;30(1):31-33. doi:10.1097/01.ICL.0000101488.84455.E6
2. Elving KH, Haasnoot AJW, Ghyczy EAE, Stramrood S, de Boer JH. Contact lenses in paediatric aphakia in the Netherlands; A multicentre retrospective chart study. Cont Lens Anterior Eye. 2024;47(3):102163. doi:10.1016/j.clae.2024.102163
3. Yan H, Li L, Liang T. Rigid Corneal Lenses for Visual Rehabilitation in Infants With Unilateral Aphakia After Cataract Surgery: A Longitudinal Case Series. Eye Contact Lens. Published online February 6, 2025. doi:10.1097/ICL.0000000000001173
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7. Khosravi Mirzaei S, Feizi S, Hatami F, Hatami F, Moshtaghion SM. Contact lenses for visual rehabilitation in post-keratoplasty eyes: A systematic review. Cont Lens Anterior Eye. Published online January 28, 2025. doi:10.1016/j.clae.2025.102374
8. Zheng B, Shen L, Walker MK, et al. Clinical evaluation of rigid gas permeable contact lenses and visual outcome after repaired corneal laceration. Eye Contact Lens. 2015;41(1):34-39. doi:10.1097/ICL.0000000000000061
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10. de Juan V, Martín R, Rodríguez G. Bitoric rigid gas permeable contact lens fitting for the management of a corneal scar caused by herpes zoster ophthalmicus. Clin Exp Optom. 2012;95(2):229-232. doi:10.1111/j.1444-0938.2011.00658.x
11. Itoi M, Itoi M. Management of Keratoconus With Corneal Rigid Gas-Permeable Contact Lenses. Eye Contact Lens. 2022;48(3):110-114. doi:10.1097/ICL.0000000000000876
    Shorter E, Schornack M, Harthan J, et al. Keratoconus Patient Satisfaction and Care Burden with Corneal Gas-permeable and Scleral Lenses. Optom Vis Sci. 2020;97(9):790-796. doi:10.1097/OPX.0000000000001565
12. Sengor T, Kurna SA, Aki S, Ozkurt Y. High Dk piggyback contact lens system for contact lens-intolerant keratoconus patients. Clin Ophthalmol. 2011;5:331-335. doi:10.2147/OPTH.S16727