Scleral lenses are large-diameter rigid gas-permeable lenses used primarily by individuals with complex vision needs or chronic ocular surface diseases. This specialized lens design is recommended for conditions like keratoconus, severe dry eye disease, and corneal irregularities resulting from surgery or injury. The lens’s size and fit contribute to its exceptional comfort profile, setting it apart from standard contact lenses that rest directly on the eye’s most sensitive surface.
The Unique Design That Prioritizes Comfort
The superior comfort of scleral lenses stems from their unique mechanical interaction with the eye. Unlike conventional lenses that sit on the highly innervated cornea, scleral lenses vault completely over the corneal tissue. They rest instead on the less sensitive sclera, the white part of the eye, which contains far fewer nerve endings than the cornea. This vaulting action minimizes the friction and irritation typically associated with smaller, corneal-resting rigid lenses.
The design creates a fluid reservoir 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 constant, hydrating cushion for the cornea. This continuous bathing effect is beneficial for those with severe dry eye, preventing the lens from exacerbating dryness and promoting a stable, moist environment. The fluid layer also smooths over corneal irregularities, providing sharp, stable vision.
The Critical Role of Proper Fitting
Achieving comfort with a scleral lens depends on a customized fitting process. The lens must rest on the sclera without creating excessive suction or localized pressure points that could lead to discomfort or tissue damage. This process begins with advanced diagnostic imaging, such as corneal topography, which creates a detailed, three-dimensional map of the eye’s surface contours.
Eye care professionals use these measurements to select an initial diagnostic trial lens set. The fit is evaluated by assessing the “vault,” or the space between the lens and the cornea. Too little vault can cause the lens to touch the cornea, while too much can lead to issues like midday fogging or reduced oxygen transmissibility. Multiple adjustments are necessary to ensure the lens is stable and comfortable for extended wear.
Adjusting to Insertion and Wear
The initial experience of wearing scleral lenses involves a learning curve, primarily due to their larger size compared to traditional lenses, which can range from 14.5 to 24 millimeters in diameter. Insertion and removal require a specific technique, often involving a suction device or specialized finger placement, and the lens must be filled with saline before application. This initial process can feel foreign and awkward, contributing to a temporary sense of bulkiness.
During the first few days to weeks of wear, patients commonly experience an initial awareness of the lens. The eyes and eyelids need time to adapt to the lens’s positioning and size. For most individuals, full adaptation, where the lens becomes virtually unnoticeable, occurs within one to two weeks, though those with more complex eye conditions may take slightly longer. It is important to gradually increase wear time to allow the eyes to acclimate smoothly.
Maintaining Comfort During Extended Use
Sustaining all-day comfort with scleral lenses requires meticulous care and adherence to maintenance routines. A common issue that can reduce comfort is protein or lipid buildup on the lens surface or debris entering the fluid reservoir, which can cause symptoms like blurry vision or irritation. To combat this, a strict hygiene routine involving daily cleaning with an approved solution and a gentle rubbing technique is necessary.
The saline solution used to fill the lens bowl before insertion must always be sterile and preservative-free to prevent irritation to the ocular surface. Additionally, the gas-permeable material of the lens must allow sufficient oxygen to reach the underlying cornea, a specification that is carefully considered by the eye care professional during the fitting process. Following the prescribed wearing schedule, which usually limits wear to a maximum of 12 to 14 hours, and attending regular follow-up appointments are necessary steps to ensure the lens fit remains optimal and comfort is maintained over time.