If we ask our scleral lens patients what they struggle with the most, the top responses tend to be difficulty with lens handling, ocular injection, or blurry vision after several hours of wear. What if we could design a scleral lens to circumvent these problems? I was recently listening to an online seminar by Daddi Fadel, DOptom, and Donald Ezekiel, AM, Dip Opt Wa, DCLP, in which they described a lens that could do just that: a fenestrated scleral.

Fenestrated scleral lenses were first proposed in the 1930s and brought into the mainstream by Josef Dallos (1946) and Norman Bier (1945), both of whom noted increased lens comfort and improved corneal physiology when a hole was ground into a glass scleral lens. Dr. Ezekiel recommends utilizing three fenestrations placed in a triangular shape over the cornea and limbus (Figure 1); this often creates a large air bubble under the lens in the corneolimbal area (Figure 2) (Fadel and Ezekiel, 2020). It is important that this air bubble moves with the blink to prevent corneal desiccation and that it remains in the periphery for unobstructed vision. Following are some of the many benefits of fenestrations in scleral lenses.

Advantages of Fenestrations

Easier Handling Unlike traditional scleral lenses, fenestrated sclerals do not need to be filled with saline prior to application, although wetting the lens initially is recommended (Fadel and Ezekiel, 2020). This simplifies the application process, as patients would not need to be face-down when applying a lens. Application and removal plungers are not necessarily needed; the fenestrations reduce lens suction, so patients would be able to apply and remove their lenses with just their clean fingers.

Improved Visual Quality Decreased vision after several hours of traditional scleral lens wear can be attributed to corneal hypoxia changes or, more commonly, to midday fogging, which occurs only with non-fenestrated sclerals. The cause of midday fogging is not entirely understood, but it appears to be multifactorial and may be related to mucin production secondary to conjunctival irritation combined with lens suction. The fenestrated scleral lenses described by Dr. Ezekiel were designed with a fluid reservoir depth of less than 100µm to 150µm (Fadel and Ezekiel, 2020). A lower central clearance offers overall improved visual quality and a potential reduction in midday fogging. The pressure difference under the lens is also minimized with the incorporation of a fenestration, which reduces lens suction, decreases conjunctival frictional forces, and allows constant debris removal via tear exchange.

Free Oxygen and Tear Exchange Corneal hypoxia is a constant concern among scleral lens practitioners. A fenestrated scleral lens designed with a hyper-Dk material and thin fluid reservoir maximizes oxygen transmissibility and allows constant oxygen and fluid exchange. If patients are experiencing corneal edema with traditional scleral lenses and a surgical consult is their next stop, a fenestrated scleral lens may offer an alternative option.

Hope for Scleral Lens Failures

Currently, fenestrated scleral lenses are not heavily incorporated in my practice, and I have not attempted this method of utilizing three fenestrations in a single lens. I am excited to try this option and hope to offer it to those who have failed traditional scleral lens wear. CLS

For references, please visit www.clspectrum.com/references and click on document #303.