Scleral lenses are one of the most effective treatment options for the management of corneal irregularities and severe ocular surface diseases. Unlike ordinary contact lenses, scleral lenses have a unique design that makes them ideal for this purpose. Not only are these lenses larger than conventional contact lenses, offering greater stability and ease with which they are placed, but they also have a vaulted design. This means that they touch the sclera but vault over the cornea, leaving a space between the back of the contact lens and the surface of the eye. These specialty contact lenses are completely bespoke and made to the individual specifications of each patient’s eyes.
In the past, the assumption was that, like the cornea, the sclera features a curved shape. However, studies have revealed that from the peripheral cornea onwards, for most patients, the sclera continues in a straight line. Scleral shapes can also be inconsistent from one meridian to the next.
Since every patient is unique, the best way to ensure the most accurate and comfortable fit for scleral lenses is to perform scleral topography.
Scleral topography is a highly advanced imaging technique that uses triangulation and structured laser light to map the scleral surface and provide the patient with a custom-designed lens that is unique.
Scleral topographers can measure the entire ocular surface out to 22mm in diameter, identifying the clear cornea and the conjunctiva and creating a 3D model of the eye that can be used to supply measurements with pinpoint accuracy. It can also be used to customize the scleral lens design.
Scleral lenses are fit based on sagittal height. Sagittal height can be measured at a single location or as a mean for a given chord diameter. It increases in areas of the sclera that are steeper in curvature and decreases where the sclera is flatter. Different elevations appear as different colors on the produced scleral elevation map, providing a clear overall insight into the shape of the front surface of the eye.
Before scleral topography, trying multiple scleral diagnostic lenses was the only way to try to determine the primary parameters needed to create scleral lenses. However, there are many limitations with this. Diagnostic lenses typically have a single or at most two different curves in the periphery. Many eyes need a different curve in four or more meridiens. Also, most optometrists don’t often fit scleral lenses and it can take a very long time for a practitioner who rarely performs this to become proficient at this process and create the lenses with the very highest levels of accuracy and precision. Dr. Kaufman at Factoria Eye Clinic specializes in scleral lens fitting and utilizes the most cutting-edge technologies to create each lens.
Using scleral topography to inform scleral lens design will help ensure that each patient’s lenses achieve the best possible fit and the highest levels of visual clarity based on their individual needs.
Find out more about how scleral shape applies to custom scleral lens design by speaking to our experienced and knowledgeable eyecare experts at Factoria Eye Clinic in Bellevue, Washington today. You can reach us by calling (425) 641-2020.
Dr. Kaufman's scleral topography shows that even someone with
'normal' corneas can have a sclera which requires a quad-specific shape