About scleral contact lenses

Scleral lenses are a type of contact lens used to treat a variety of eye and vision conditions. These lenses are larger than regular contacts, allowing them to rest on the sclera (the white part of the eye) and conjunctiva (the clear tissue lining the front of the eye and inner eyelids). They arch over the cornea (the clear front layer of the eye), creating a smooth, even surface that enhances vision correction.

Read on to learn what scleral contact lenses are used for, how they work, and how they compare to other contact types.

What are scleral contact lenses?

Scleral lenses are named for their resting position on the eye. While other types of contacts sit directly on the cornea, the centre portion of a scleral lens vaults (arches) over the cornea to create a dome-like space. Functioning as a fluid reservoir, this space holds a solution to keep the eye lubricated during contact lens wear.

Scleral contact lenses are a type of rigid gas-permeable lens. Gas-permeable contacts are made from a material that allows oxygen to pass through and reach the cornea. Oxygen permeability is necessary for corneal health, as it reduces the risk of corneal infections and other complications.

Scleral contacts have been around for over a century and were initially used to correct irregular astigmatism, a condition where the corneal surface is uneven. Early scleral lenses were handmade or crafted using blown-glass techniques that were far less precise than today’s advanced manufacturing technology.

Modern scleral contact lenses have evolved to address a broader range of eye and vision concerns, from corneal irregularities to ocular surface diseases. They’re also used for cosmetic and theatrical purposes because of the balance of comfort and visual clarity they provide.

Types of scleral lenses

Scleral contact lenses come in different types and sizes to meet various vision correction needs, such as:

• Full scleral – These full-eye contacts are the largest of the scleral types and cover the entire front surface of the eye. They also create the greatest amount of space between the contact lens and the cornea.
• Mini-scleral – These mid-sized lenses rest on the front of the sclera.
• Corneo-scleral and semi-scleral – As the smallest scleral options, these contacts sit on the eye’s surface at the junction of the sclera and cornea.

Are scleral lenses hard or soft?

Scleral contact lenses are rigid gas-permeable lenses, meaning they are a hard type of contact lens. Their rigidity helps them maintain their shape and a smooth surface for optimal vision correction. Hard contacts are also highly durable and known for providing sharper vision compared to other lens types. They’re typically replaced less frequently than soft contacts.

If you’re a candidate for scleral contact lenses, your eye care provider can recommend the ideal type for your eye and vision needs.

What are scleral lenses for?

Scleral contact lenses can be used to correct common refractive errors, which are conditions that cause blurry vision. These include:

• Myopia (short-sightedness) – Blurry distance vision
• Hyperopia (long-sightedness) – Blurry near vision
• Presbyopia – Age-related changes causing blurry near vision
• Astigmatism – Blurry vision at all distances

But they are particularly beneficial for conditions affecting the cornea, such as:

Irregular Corneal Shape

An irregular corneal shape can make it difficult to fit a traditional contact lens since it sits directly on the corneal surface. Corneal irregularities may result from:

• Conditions that cause corneal bulging (such as keratoconus and pellucid marginal degeneration)
• Corneal infection
• Corneal injury
• Corneal damage or scarring
• Post-surgical complications (such as those following LASIK or corneal transplantation)

Ocular Surface Diseases

These are conditions that affect the surface of the eye and may be caused by various factors. One common ocular surface disease is dry eye syndrome, which affects the amount or quality of tears the eyes produce.

Other factors may also make someone a candidate for scleral lenses. For instance, people with normal corneas who have trouble wearing traditional contacts due to eye allergies or corneal sensitivity may find scleral contact lenses more comfortable. 

How do scleral lenses work?

Scleral contact lenses are custom-made, offering a precise, personalised fit for each individual. The customisation process uses detailed measurements from an eye exam to create an exact fit for your eye shape. These lenses work by:

• Vaulting over the cornea – Scleral lenses arch over the cornea, forming a smooth surface that can correct corneal irregularities and improve your vision.
• Creating a fluid reservoir – The space between the scleral contact lens and cornea functions as a reservoir to hold preservative-free saline or another solution approved for use with a scleral lens. This fluid keeps the front of the eye hydrated and maintains the eye’s moisture throughout the day.
• Providing stability – Due to their larger size and design, scleral contact lenses are less likely to shift or fall out. Their edges rest above and below the eyelid margins, which helps keep them securely in place.
• Enhancing visual clarity – Scleral contact lenses can correct severe astigmatism and other refractive errors. Their rigid structure and customisation can also provide crisper, clearer vision.
• Ensuring breathability – The gas-permeable material the lenses are made from allows oxygen to reach the cornea, promoting corneal health. 

Getting these lenses often involves several steps to fine-tune and obtain the proper fit. This helps ensure they sit correctly on your eyes, work properly, and provide optimal comfort.

Are scleral lenses comfortable?

Scleral contacts are generally comfortable since they don’t rest on the cornea, which is more sensitive than the sclera. Their customised fit also enhances comfort. However, as with all types of contacts, there may be an adjustment period when first wearing them.

Many people can wear scleral contact lenses for 10 or more hours, especially once they get used to them. Your eye care provider can discuss how long you should wear your contacts as you adjust to them.

Can you sleep in scleral lenses?

It’s not advisable to sleep with any contact lenses in, including scleral lenses. Sleeping in contacts increases your risk of developing an eye infection and other problems. Always remove your contacts before bed and follow your eye care provider’s cleaning recommendations.

Scleral lenses vs. contact lenses

A scleral contact lens differs from other types of contacts in several ways:

Placement on the eye
Scleral lenses rest on the sclera and conjunctiva, while standard gas-permeable lenses and soft contact lenses sit on the cornea.

Replacement schedule

Soft lenses may be replaced daily, biweekly, or monthly, depending on the type selected, while scleral lenses typically last one to two years before needing replacement. 

Size

Most scleral contact lenses range from 14mm to 25mm in diameter, though some may be smaller or larger. This is much larger than the average size of traditional gas-permeable contacts (9mm to 9.5mm) and soft contacts (13.8mm to 14.5mm). 

Cost

The cost of scleral contacts may be higher than other contact lenses, as they are custom-made for each wearer. However, scleral lenses are replaced less frequently than other types of contacts.

Comfort

Because they rest on the sclera and conjunctiva, scleral lenses may be more comfortable for some people than traditional contacts, which sit on the more sensitive cornea.

All contacts must be prescribed by a licensed eye care provider. Unlike other types of contact lenses, scleral contacts are custom-made and can only be ordered through your eye care professional.

Scleral contact lenses offer a versatile vision correction solution for many people. To learn more about these and other types of contact lenses, book an eye exam or contact lens check with Vision Express, our partner in eye care.

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