PREVIOUSLY, THIS COLUMN has addressed the questions of when scleral lenses (SLs) should be utilized as treatment for dry eye and which fitting techniques should be considered for patient success (Andrzejewski, 2024). But even with an optimal lens fit, dry eye patients may still report discomfort, often describing symptoms of dryness, even though corneal staining and other clinical signs show improvement. With a SL, there are two relationships to consider: lens to eyeball (“the fit”) and lens to eyelid. In the absence of neuropathic pain, three key factors—evaporation, peripheral exposure, and eyelid friction—are likely culprits.

TEAR EVAPORATION

Although SLs protect the ocular surface, their anterior surface is vulnerable to environmental factors, such as low humidity and wind, which can exacerbate tear evaporation. An already impaired lipid layer, which many dry eye patients have, coupled with the disruption to the tear film (TF) caused by all contact lenses (CLs) (Craig et al, 2013), results in evaporation on the SL surface, contributing to discomfort and friction with blinking.

PERIPHERAL EXPOSURE

SLs cover the cornea and part of the sclera. Depending on a patient’s eyelid anatomy and the lens diameter selected, scleral lenses inherently leave the peripheral conjunctiva exposed. This can lead to conjunctival desiccation and mechanical irritation.

Additionally, the SL edge—given it’s so much thicker than that of a soft CL—may create localized disruption in the TF, which in the presence of a well-fit SL, can cause peripheral conjunctival staining and injection reminiscent of 3 and 9 o’clock staining. For patients who have preexisting conditions such as conjunctivochalasis, mechanical interactions between the lens edge and the conjunctiva can amplify irritation and have a pronounced effect on tear film instability (Yokoi et al, 2005).

EYELID FRICTION AND LID WIPER EPITHELIOPATHY (LWE)

Perhaps the most significant contributor to discomfort in SL wearers is eyelid friction, particularly when accompanied by LWE. The lid wiper, a specialized region of the palpebral marginal conjunctiva, interacts with the lens surface during blinking to spread the TF (Korb et al, 2002). Excessive friction between the lid wiper and the SL, especially in the presence of insufficient ocular lubrication, can result in mechanical trauma, leading to inflammation and damage to the epithelial cells (Kunnen et al, 2018).

LWE is characterized by staining of the lid wiper area and is frequently associated with increased dryness and discomfort, with or without the presence of a CL (Yeniad et al, 2010). The condition leads to an uneven spreading of the tear film over the SL, and this may exacerbate lens “non-wetting,” where areas of the surface fail to maintain a smooth tear film layer, causing discomfort and blurred or variable vision.

Friction-related discomfort occurs when the lens surface is not adequately lubricated or when the tear film is unstable (Craig et al, 2013). Even though SLs provide continuous hydration posterior to the lens, the interaction between the upper eyelid and the lens surface remains a potential source of irritation.

Furthermore, incomplete blinking, which is common in contact lens wearers in general, worsens this problem by reducing TF distribution and increasing mechanical stress on the lid wiper (McMonnies, 2007).

While scleral lenses can be an excellent treatment choice for many dry eye patients, achieving improved comfort may require addressing more than the fit of the lens itself. Optimizing the TF and minimizing friction are essential for maintaining comfortable SL wear in dry eye patients.

REFERENCES

1. Andrzejewski T. Scleral Lens Consensus. Contact Lens Spectrum. 2024 Dec;39:E1. Available at clspectrum.com/issues/2024/novemberdecember/dry-eye-dx-and-tx. Accessed 2024 Jan 8.

2. Craig JP, Willcox MD, Argüeso P, et al. The TFOS International Workshop on Contact Lens Discomfort: report of the contact lens interactions with the tear film subcommittee. Invest Ophthalmol Vis Sci. 2013 Oct 1;54:TFOS123-TFOS156.

3. Yokoi N, Komuro A, Nishii M, et al. Clinical impact of conjunctivochalasis on the ocular surface. Cornea. 2005 Nov;24:S24-S31.

4. Korb DR, Greiner JV, Herman JP, et al. Lid-wiper epitheliopathy and dry-eye symptoms in contact lens wearers. CLAO J. 2002 Oct;28:211-216.

5. Kunnen CME, Wolffsohn JS, Ritchey ER. Comparison of subjective grading of lid wiper epitheliopathy with a semi-objective method. Cont Lens Anterior Eye 2018 Feb;41:28-33.

6. Yeniad B, Beginoglu M, Bilgin LK. Lid-Wiper Epitheliopathy in Contact Lens Users and Patients With Dry Eye. Eye Contact Lens. 2010 May;36:140-143.

7. McMonnies CW. Incomplete blinking: exposure keratopathy, lid wiper epitheliopathy, dry eye, refractive surgery, and dry contact lenses. Cont Lens Anterior Eye. 2007 Mar 1;30:37-51.