THE TEAR FILM consists of the corneal-facing mucin-protein-aqeuous phase and anterior lipid layer. A contact lens on the eye further divides the tear film into two distinct layers: the pre-lens (outer) and post-lens (inner) tear film. Lens wear has been shown to affect all tear layers by altering mucin production, aqueous flow rate, and tear protein concentrations (Rohit et al, 2013). In addition, the pre-lens lipid layer is reduced with lens wear (Rohit et al, 2013).

A thinner lipid layer is associated with a shorter tear breakup time, as well as decreased lens wear comfort, with both hydrogel and silicone hydrogel lenses (Rohit et al, 2013).

Contact lens-related discomfort and dry eye may even be linked to inflammatory changes. It was found that end-of-day comfort was reduced when wearing soft lenses compared to no lens wear and that the increased concentration of prolactin-induced protein throughout the day correlated with decreased ocular comfort (Masoudi et al, 2016).

Inflammatory mediators, including interleukins, were increased in tears from contact lens-related dry eye in soft lens wearers compared to normal subjects (Ramamoorthy et al, 2022). In addition, patients who have dry eye and wear soft contact lenses showed higher ocular surface staining scores, more inflammatory cytokines and neuromediators in their tears, and higher corneal dendritic cell density than patients who have dry eye disease and do not wear lenses (Yang et al, 2022).

In addition, contact lens wear impacts the structure and function of meibomian glands. When the influence of rigid GP and hydrogel lenses on the meibomian glands was investigated, results showed a significantly greater degree of meibomian gland shortening and loss in contact lens wearers compared to non-wearers (Arita et al, 2009). It was similarly demonstrated that soft lens wear was associated with higher levels of meibomian gland dropout (Alghamdi et al, 2016). However, discontinuation of lens wear did not lead to improvement in gland appearance, suggesting that eyelid changes from lens wear may be long-standing (Alghamdi et al, 2016).

How should practitioners respond to ensure the best contact lens-wearing experience for patients? First, an evaluation must be performed to determine contact lens candidacy. If dry eye disease is detected, prime the ocular surface before lens wear. This may include treatment with artificial tears, punctal occlusion, lid hygiene, topical medications, or whole-body hydration (Walsh et al, 2012; Jones et al, 2017). Next, the proper contact lens material and modality must be selected.

For those who have dry eye, daily disposable soft lenses might be considered; refitting patients from monthly or two-week replacement lenses has been shown to contribute to lower tear osmolarity (Garaszczuk et al, 2020). For planned replacement, a biocompatible lens-solution combination and proper hygiene habits are necessary to maintain comfortable and healthy wear (Sindt and Longmuir, 2007; Efron et al, 2013). Dietary supplementation with omega-3 fatty acids has also been demonstrated to improve dry eye symptoms and lens wear comfort in contact lens wearers (Bhargava and Kumar, 2015).

Regarding digital display use, holding devices at lower gaze angles may cause less tear film disruption; using artificial tears during short periods of screen time has also been effective in addressing dry eye in both lens wearers and non-wearers (Talens-Estarelles et al, 2022). Additionally, nasal neural stimulation with varenicline has been shown to increase endogenous tear production (Pflugfelder et al, 2022); although not studied, this may be helpful for contact lens wearers who want an alternative to artificial tears.

In conclusion, contact lens-induced dry eye is a common reason for lens wear discontinuation (Richdale et al, 2007; Pritchard et al, 1999). Fortunately, eyecare practitioners have access to many contact lens designs and modalities, as well as dry eye treatments. In the end, the relationship between contact lenses and dry eye doesn’t have to be so complicated. CLS

References

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