Custom Gas Permeable Contact Lenses
What Are Custom Gas Permeable Lenses?
Custom GP lenses are rigid contact lenses made to the precise measurements of your individual cornea. Unlike soft lenses that come in standard sizes, every custom GP lens is ordered specifically for your eye using detailed corneal mapping data.
Your eye doctor captures a high-resolution digital map of your corneal surface before any lens is ordered. This map guides every design decision, including the base curve, diameter, edge shape, and optical zone. The result is a lens that fits your eye the way no off-the-shelf option can.
The rigid surface of a GP lens creates a smooth optical interface over irregularities in the cornea, which is why many patients with corneal conditions see far more clearly with GP lenses than with soft lenses.
Today's custom GP lens materials have high oxygen transmissibility, meaning your cornea receives the oxygen it needs during daily wear. This is very different from older hard lenses made of PMMA plastic, which blocked oxygen entirely.
Your eye doctor selects the material that best matches your corneal condition, wearing schedule, and tear film health to give you the most comfortable and clear lens possible.
Soft lenses are flexible and drape over the shape of your cornea, including any irregularities. A GP lens holds its shape and creates a smooth, uniform tear layer between the lens and your corneal surface. This is what produces sharper, higher-contrast vision for patients with corneal irregularities or complex prescriptions.
Who Benefits from Custom GP Lenses?
Custom GP lenses are designed for patients whose corneas cannot be fitted with standard contact lens parameters. Our team has deep experience fitting patients with a wide range of conditions that standard lenses simply cannot address.
Keratoconus is a condition in which the cornea gradually thins and takes on a cone-like shape, distorting vision in ways that glasses and soft lenses cannot fully correct. Post-surgical ectasia, which can occur after procedures like LASIK, creates similar irregularities.
Custom GP lenses are a well-established and effective option for these patients because the rigid lens surface overrides the corneal shape and delivers a stable, clear optical surface.
Regular astigmatism follows a predictable pattern that soft toric lenses can correct. Irregular astigmatism, caused by scarring, corneal transplants, or unusual corneal curvature, does not follow that pattern and is difficult to correct with soft lenses.
Custom GP lenses are designed to handle both regular and irregular astigmatism, including high prescriptions that fall outside standard lens ranges. For patients with pediatric aphakia (absence of the natural lens, often following early cataract surgery in children), custom parameters are also available.
Patients with severe dry eye or compromised corneal surfaces sometimes do better with GP lenses than soft lenses, particularly when fitted with scleral lens designs that vault the cornea entirely. For corneal GP lenses specifically, adequate tear film is important for comfort, and your eye doctor will evaluate your ocular surface before recommending the best lens type for you.
Our Custom Fitting Process
Fitting custom GP lenses is a multi-step process that requires precision and patience. Our optometry team, which includes specialists with decades of experience in GP and specialty lens fitting, guides you through each stage.
The fitting begins with computerized corneal topography, a painless scan that creates a detailed map of the curves and elevations across your corneal surface. Your eye doctor uses this data to select the initial lens parameters before any trial lens is placed on your eye.
This mapping step reduces guesswork and gives our team a strong starting point for your custom lens design.
Your eye doctor places a diagnostic trial lens on your eye and evaluates the fit under a slit lamp microscope, a magnifying instrument used to examine the eye in detail. The evaluation checks how the lens centers, moves, and exchanges the tear layer beneath it. An overrefraction, which is a prescription check performed with the lens in place, determines your final corrective power.
You may try one or two trial lenses before your doctor finalizes the design for your custom order.
Your custom GP lens is manufactured by a specialty laboratory to your exact specifications. Fabrication typically takes one to two weeks. At your delivery appointment, your eye doctor confirms the fit, checks your vision, and makes any needed adjustments to the lens parameters.
Plan for three to four total visits across the fitting process: initial topography, trial lens evaluation, lens delivery, and one or two follow-up appointments for fine-tuning.
Adapting to Custom GP Lenses
Rigid lenses feel different from soft lenses, and most new wearers go through an adjustment period. Understanding what to expect helps you stay on track and give your lenses a fair chance.
Because a GP lens is rigid, you will feel its edge against your eyelids at first. This is normal and not a sign that the lens fits poorly. An adaptation period of one to two weeks is typical for new GP wearers.
Your eye doctor may recommend starting with a few hours of wear each day and gradually adding time as your eyelids adjust.
Most patients reach ten to fourteen hours of comfortable daily wear within two to three weeks. Wearing your lenses consistently every day during adaptation helps your eyelids adjust more quickly. Taking frequent days off can slow the process.
Because the rigid material resists protein and lipid deposits better than soft lenses, many patients find their vision stays clear and consistent throughout the wearing day once adaptation is complete.
Some patients are unable to adapt to the edge sensation of a corneal GP lens despite a well-fitted design. If this applies to you, your eye doctor may recommend alternatives such as scleral lenses, which rest on the white of the eye and vault completely over the cornea, hybrid lenses with a rigid center and soft outer skirt, or a piggyback system where a soft lens is worn under the GP lens for cushioning.
Our team has the experience to guide you toward the option that best balances vision quality and comfort for your eyes.
Caring for Your Custom GP Lenses
Custom GP lenses are durable and long-lasting, but they do require consistent daily care. Following your care routine protects both your lenses and your corneal health.
After each wear, rub your lenses with a GP-specific cleaning solution and rinse them thoroughly with approved saline. This removes the proteins, lipids, and debris that accumulate during the day.
Never use tap water, saliva, or homemade solutions on your GP lenses, as these can introduce harmful bacteria and damage the lens surface.
Store your lenses overnight in a conditioning or soaking solution that disinfects the lens and keeps it from drying out. Always use fresh solution and never top off old solution in your case. Replace your lens case every one to three months to prevent bacterial buildup.
Your eye doctor will recommend the specific solutions that work best with your lens material and your individual ocular surface.
With proper care, custom GP lenses typically last one to three years. Their rigid material resists surface wear and deposit accumulation far better than soft lens materials.
Your eye doctor inspects your lenses at each follow-up visit for scratches, warping, and deposit buildup. If your prescription changes or your corneal shape shifts, a new lens may be needed before the old one reaches the end of its lifespan.
When to Contact Your Eye Doctor
Custom GP lenses are precise tools, and even small changes in fit or corneal shape can affect your vision and comfort. Knowing when to reach out to your eye doctor helps you protect your eye health between scheduled visits.
Contact your eye doctor if your vision becomes blurry, if lenses that once felt comfortable now cause irritation, or if the lens appears to move more than usual or no longer centers properly. These changes may indicate a corneal shape shift, lens warping, or deposit accumulation.
New redness, tearing, or sharp pain during wear should prompt a prompt visit to rule out a corneal abrasion or infection.
If your custom GP lens cracks, chips, or develops a visible scratch, stop wearing it immediately and contact your eye doctor for a replacement. A damaged lens edge can scratch the corneal surface and cause real harm.
Keep a pair of current glasses available as a backup so you can see safely while your replacement lens is being fabricated. Your doctor can typically use your existing measurements to speed up the reorder process.
Your eye doctor monitors your corneal health and lens fit every six to twelve months, or more frequently if you have a progressive condition like keratoconus. These visits include a lens evaluation, updated corneal topography, and a prescription check.
Regular follow-up is one of the most important parts of custom GP lens wear. Catching small changes early prevents bigger problems down the road.
Our Specialty Contact Lens Team
Our optometry team brings specialized training and years of hands-on experience to every GP lens fitting. Each of our specialists approaches complex cases with the precision and patience they require.
Dr. Paul Zerbinopoulos has been fitting scleral lenses since 2008 and is a past president of the Rhode Island Optometric Association. His deep expertise in specialty contact lenses makes him a trusted resource for patients with keratoconus, irregular corneas, and difficult-to-fit eyes.
Dr. Earle Scharff brings more than 40 years of experience in contact lens care, with particular expertise in rigid gas permeable lenses, multifocal designs, toric lenses for astigmatism, and scleral lenses. His extensive clinical background means he has seen and successfully fitted some of the most complex lens cases.
Dr. Lori Boivin has a background in specialty lens fittings and trained at Massachusetts Eye and Ear, one of the leading academic eye care institutions in the country. She brings that training to our patients who need precise, individualized lens designs.
Frequently Asked Questions
Here are answers to questions our patients often have about custom GP lenses that go beyond what is covered above.
Standard GP lenses work well for many patients with regular prescriptions and healthy corneas. Custom GP lenses become necessary when your cornea falls outside standard fitting parameters, such as when you have an irregular shape, extreme curvature, or a condition like keratoconus. If a standard GP lens cannot achieve a stable, comfortable fit or deliver sharp vision, your eye doctor will use your topography data to design a fully custom option. The decision is always based on your actual corneal measurements, not just your diagnosis.
Yes. Custom GP lenses are used in pediatric care for conditions such as keratoconus that appears in adolescence and pediatric aphakia (absence of the natural lens). The fitting process is the same, but our team works carefully to ensure the child is a good candidate in terms of maturity and the ability to handle and care for the lenses safely. Our pediatric eye care team and optometry specialists coordinate on these cases when needed.
Coverage varies widely depending on your vision and medical insurance plans. When custom GP lenses are medically necessary, such as for keratoconus or post-surgical ectasia, some medical insurance plans may cover a portion of the fitting fees or lens costs. Standard vision plans typically cover routine contact lens fittings but may not cover specialty lens fees. We recommend contacting your insurer before your fitting appointment so you understand your benefits and any out-of-pocket costs.
Keratoconus can progress over time, which may change how your custom GP lens fits and how well it corrects your vision. This is one reason routine follow-up visits that include updated corneal topography are so important. If your corneal shape shifts significantly, your eye doctor will design a new lens based on your updated measurements. In some cases, if progression is ongoing, your eye doctor may discuss corneal cross-linking, a procedure performed by our cornea specialists, to help stabilize the cornea before refitting.
Any contact lens carries a small risk of infection if not cared for properly. The key protective steps are following your cleaning and storage routine consistently, never using tap water on your lenses or case, replacing your lens case regularly, and removing lenses if your eye becomes red or painful. Custom GP lenses are not worn overnight, which reduces infection risk compared to extended-wear soft lenses. If you ever experience sudden pain, significant redness, or vision changes while wearing your lenses, remove them immediately and contact our office.
Schedule Your Custom GP Lens Fitting at Rhode Island Eye Institute
If standard contact lenses or glasses are not giving you the clear, comfortable vision you need, our specialty contact lens team is here to help. At Rhode Island Eye Institute, our experienced optometrists use advanced corneal mapping technology and years of specialty fitting expertise to find the right lens solution for your eyes. We invite you to schedule a consultation and take the first step toward clearer, more comfortable vision.