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Contact Lens Spectrum

Article

THE SCLERAL LENS VAULT

THE OBSTACLE CHALLENGE

By: GRACE TSENG, OD, PAM SATJAWATCHARAPHONG, OD
Contact Lens Spectrum June 1, 2021 Vol 36, Issue June 2021 Page(s): 46

Obstacles on the conjunctiva can pose challenges for scleral lens fitting. Pressure over these raised areas can cause discomfort, redness, impingement of blood flow, ocular surface irritation, and debris accumulation in the tear reservoir entering from the space adjacent to the elevation.

Strategies to Avoid Scleral Obstacles

Flatten the Landing Zone For relatively flatter obstacles, flattening the landing zone may relieve compression on the elevated area. Flatten along one meridian in a toric-landing-zone design or along one quadrant in a quadrant-specific design depending on the location, size, and amount of elevation of the obstacle.

Reduce Landing Zone Diameter If the obstacle extends only minimally into the landing zone, reducing landing zone diameter or changing to a design with a smaller landing zone may be beneficial. With the former, ensure that sufficient landing area remains to support the weight of the lens to avoid excessive pressure and discomfort.

Notches and Vaults Notches are areas cut from the landing zone to avoid the obstacle, while vaults are localized elevated areas of the landing zone to fit over a raised obstacle. Both designs require application in the appropriate orientation as well as rotational stability of the lens. Lens stability can be achieved with front-surface stabilization or with back-toric/quadrant-specific designs.

While notches require the location, width along the lens edge, and the extent of the obstacle into the lens edge, vaults require its depth as well. It is helpful to describe the obstacle location relative to rotational marks on the lens or to draw the location on the lens. Ensure that notches and vaults are not too large, which may cause lens awareness and poor sealing of the corneal chamber, allowing debris to enter.

Profilometry-Guided Lens Design Scleral topography has provided better understanding of scleral shape and can image conjunctival obstacles. Lenses designed from this data can provide a more precise landing zone to avoid obstacles.

Impression-Based Fitting Scleral lenses designed from an impression of the eye can accurately match the ocular surface shape including surface irregularities on the conjunctiva and sclera. This is especially beneficial when patients have failed other scleral designs or have more complex elevations on the sclera.

Be Creative Depending on an obstacle’s size, location, and degree, various methods can be used or combined to provide a healthy, comfortable fit (Figures 1 through 4). CLS

Figure 1. Keratoconus patient with impingement of a pinguecula with toric landing zone.
Figure 1. Keratoconus patient with impingement of a pinguecula with toric landing zone.
Figure 2. Attempt to avoid the pinguecula with a landing zone notch was unsuccessful.
Figure 2. Attempt to avoid the pinguecula with a landing zone notch was unsuccessful.
Figure 3. Attempt to avoid the pinguecula with landing zone vault was unsuccessful.
Figure 3. Attempt to avoid the pinguecula with landing zone vault was unsuccessful.
Figure 4. An impression-based scleral lens was ultimately needed to alleviate hyperemia.
Figure 4. An impression-based scleral lens was ultimately needed to alleviate hyperemia.

Dr. Tseng was the 2020-2021 cornea and contact lens resident at UC Berkeley School of Optometry. She reports no conflicts of interest.

Dr. Satjawatcharaphong is an assistant clinical professor at UC Berkeley School of Optometry and is also past president of the Scleral Lens Education Society. She reports no conflicts of interest.

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