Scleral lenses are specialized contact lenses designed to correct vision for individuals with complex eye conditions. Unlike standard lenses that rest directly on the sensitive cornea, scleral lenses have a larger diameter and cover the entire corneal surface. This unique design allows them to rest on the less sensitive white part of the eye, known as the sclera, providing exceptional clarity and comfort.
Structure and Primary Uses
Scleral lenses are rigid gas-permeable (RGP) lenses that hold their shape while allowing oxygen to pass through to the eye. They are significantly larger than conventional contacts, with diameters often between 14.5 and 24 millimeters.
The medical necessity for these lenses is wide-ranging, often addressing issues that cause an irregular corneal shape. Common indications include keratoconus, which causes the cornea to bulge into a cone shape, or corneal ectasia following surgery. Scleral lenses are also frequently prescribed for severe dry eye syndrome, providing relief when traditional eye drops are insufficient. By creating a smooth, new optical surface, these lenses restore clear vision for those with compromised ocular surfaces.
The Mechanism of Scleral Lens Comfort
The high degree of comfort reported by many scleral lens wearers stems from the vaulting effect. The lens is precisely shaped to vault completely over the highly sensitive corneal tissue without touching it. The weight of the lens rests on the conjunctiva and sclera, which contain far fewer nerve endings than the cornea.
This vaulting action creates a small chamber between the back surface of the lens and the cornea. Before insertion, this space is filled with a sterile, preservative-free saline solution, which acts as a continuous fluid reservoir. This protective layer constantly bathes the corneal surface, providing ongoing hydration and creating a perfectly smooth interface for light refraction.
The Initial Adaptation Period
While long-term wear is generally comfortable, the initial experience involves a necessary adaptation period. The primary challenge for new users relates to the lens’s size and the precise technique required for insertion and removal. Because of their diameter, scleral lenses are applied using a specialized plunger and must be filled with solution before being placed onto the eye.
New wearers may experience an initial “awareness” or sensation of fullness on the eye, especially during the first few days. This feeling is not typically pain, but the brain adjusting to the presence of a larger object covering the ocular surface. For most patients, the learning curve for handling the lenses and the period of physical adjustment lasts from a few days up to one or two weeks. Consistent wear and adherence to the eye care practitioner’s instructions are important for a smooth transition.
Maintaining Long-Term Comfort
Sustaining the comfort of scleral lenses requires consistent maintenance and professional oversight. A common issue that interrupts long-term comfort and clarity is mid-day fogging, which presents as hazy or cloudy vision after several hours of wear.
This occurs when microscopic debris, such as lipids or inflammatory byproducts from the tear film, accumulates in the fluid reservoir beneath the lens. When fogging occurs, the standard solution is to remove the lens, clean it, refill it with fresh sterile solution, and reinsert it. Using a slightly more viscous, preservative-free drop to fill the reservoir can sometimes help reduce the rate of debris accumulation.
Regular follow-up appointments with the eye care specialist are necessary to ensure the lens fit remains optimal. Excessive vaulting can sometimes contribute to fogging or reduced oxygen flow. These check-ups allow for minor adjustments to the lens parameters, ensuring continued therapeutic benefits and comfort.