MEET BELINDA, a patient referred to renew her rigid corneal lenses. She’d been wearing her CLs for 50 years, renewing them only when she could no longer tolerate them, rinsing them out with water (and sometimes saliva), and feeling all the better for it. But then, the story got complicated. 

The first concern was her reduced visual acuity (20/80 OD and 20/40 OS) wearing old high myopia glasses (–18.00 –2.00 x 30 OD and –16.50 –1.50 x 170 OS). On examination, her condition appeared more complex when a macular pseudohole OD and bilateral cataracts were found. The cornea was warped secondary to years of rigid lens wear. Clear signs of moderate dry eye were also identified (i.e., corneal staining, low tear meniscus). The tear breakup time (TBUT) and meibomian glands appeared normal. 

Before looking to refit her in lenses, a referral was made to the retina specialist, who decided to postpone intervention for either the retina or the cataracts. Back to square one.

The game plan was as follows: Treat dry eyes (aqueous deficit) and restore vision as much as possible with lenses—but not the same ones.

Clearly, scleral lenses made sense in this context. First, optically it’s possible to fit a lens with a base curve and oblate profile that will significantly reduce the concave power while increasing the image size (by up to 1.75%, which is enormous!) to optimize vision. Second, the scleral lens fits in very well with a Tear Film & Ocular Surface Society Dry Eye Workshop II (DEWS II) third stage dry eye treatment algorithm (Craig et al, 2017).

It’s one thing to use a scleral lens, but it’s even more important to select the right designs to fill the reservoir.

Practitioners now recognize that unpreserved saline alone offers few advantages, especially when it comes to maintaining the cornea’s cellular metabolism (Satjawatcharaphong, 2021). Using non-preserved artificial tears enriched with electrolytes is a more effective way to nourish the cornea (Satjawatcharaphong, 2021). The more viscous nature of some products also enhances patient comfort during wear (GP Lens Institute - Scleral lens Education Society, 2024).

That said, the range of tear replacement, rewetting, and lubrication products is enormous, so which one to choose?

A recent article may shed some light (Semp et al, 2023). It shows the following:

1) Tears combining several elements—e.g., hyaluronic acid (HA) + sodium hyaluronate (SH) + trehalose—are more effective than monoagents.

2) Cationic formulations are preferred.

3) Polyethylene glycol (PEG) and sodium hyaluronate give better results than carboxymethylcellulose (CMC) and hydroxypropyl methylcellulose (HPMC).

4) Silicone acrylate is preferable to carbomer, but the latter outperforms polyvinyl alcohol and CMC.

5) Higher concentrations of liposomes are beneficial, as are hypoosmotic products.

6) Products containing phospholipids should be chosen in cases of evaporative dryness, while those containing osmoprotectants are more appropriate in cases of high tear film osmolarity.

The message is simple: Not all drops are created equal. In dry eye, as in many other areas, there’s no such thing as a magic bullet, and personalized treatment is essential to optimize results.

References

1. Craig JP, Nichols KK, Akpek EK, et al. TFOS DEWS II Definition and Classification Report. Ocul Surf. 2017 Jul;15:276-283

2. Satjawatcharaphong, P.Saline Overview. Contact Lens Spectrum. 2021 Mar; 36:46.

3. GP Lens Institute – Scleral lens Education Society. SCLERAL LENS TROUBLESHOOTING FAQs. Available at gpli.info/pdf/GPLISLSTSGuide2020.pdf. Accessed 2024 May 22.

4. Semp DA, Beeson D, Sheppard AL, Dutta D, Wolffsohn JS. Artificial Tears: A Systematic Review. Clin Optom (Auckl). 2023 Jan 10;15:9-27.