Scleral lenses and glaucoma may seem like two distant specialties in eyecare, but the reality is they are more closely related than one may assume.
Scleral lens popularity and utility has expanded greatly in the past decade. With technological advancements and expanded recognition of the versatility of a scleral lens, more practitioners are fitting scleral lenses than ever before. The rigid gas permeable (RGP) material of a scleral lens provides a smooth refractive surface, while the constant contact of the fluid reservoir to the ocular surface supports corneal epithelial healing and serves as a physical barrier.
As such, scleral lenses are indicated for improving vision, improving comfort, and/or supporting the ocular surface for a wide spectrum of conditions ranging from irregular corneal shape, high refractive error, and ocular surface disease (OSD).
The most common indications for scleral lens wear have been reported to be corneal ectasia (53%), post- penetrating keratoplasty (PKP; 17%), and ocular surface disease (18%).1 Glaucoma is a common complication of PKP and has a high prevalence in patients with OSD, with an incidence up to 20.4% in severe OSD patients.2-7 This correlation suggests that many patients who have indications like PKP or OSD for scleral lens wear, may have concomitant glaucoma.
There are several important factors to consider when fitting a glaucomatous eye with a scleral lens.
Anatomical obstacles
If a patient has had glaucoma surgery involving a tube or a bleb, you must fit over such anatomical obstacles with your scleral lens design. In eyes which are deemed candidates for scleral lens wear, preemptively select a lens design which allows you the customizability to fit over or around an anatomical obstacle. Reach out to your scleral lens lab consultants for more customized lens designs.
Can scleral lens wear impact IOP?
This is a red-hot topic. Recently, the question of the impact of IOP and scleral lens wear has been receiving a lot of attention. Several studies have been conducted to assess the impact of scleral lens wear on IOP, with varying and conflicting data (see Table 1). One critical limitation in assessing the potential impact of scleral lens wear on IOP is the lack of appropriate instrumentation to truly measure IOP while a scleral lens is on an eye.
Another limitation is that the way a scleral lens fits on an eye—with suction, which may impact IOP. Controlling for the potential impact of a scleral lens fit can be challenging in controlled studies. Additional long-term controlled prospective studies are warranted to appropriately assess the possible impact of scleral lens wear on IOP.
| Publication | Publication Date | N (Eyes) | Demographic | Instrument | Result in IOP |
|---|---|---|---|---|---|
| Shahnazi et al | 2020 | 46 | middle age/OSD | tonopen | no increase |
| Cheung et al | 2020 | 50 | healthy | iCare | increase |
| Kramer et al | 2020 | 31 | healthy | GAT | increasing trend |
| Obinwanne et al | 2020 | 20 | healthy | Schiotz | no increase |
| Samaha et al | 2020 | 20 | healthy | n/a | decrease |
| Michaud et al | 2019 | 42 | young/healthy | Diaton | increase |
Table 1: Overview of recent publications which studied the impact of scleral lens wear in intraocular pressure
Always remove the lens
A complete fit assessment of scleral lenses includes assessing the health of the eye once the lens is removed. Although a patient’s scleral lens fit may appear adequate, findings on lens removal could say otherwise. In patients with glaucoma, health assessment upon lens removal is paramount as your clinical findings could highlight changes in IOP.
Elevated IOP can impact corneal endothelial cell function which can negatively impact the pump mechanism. This reduced endothelial function may result in corneal edema.8 If corneal edema is observed following scleral lens wear, the IOP should be checked.
Mind your preservatives!
Glaucoma drops can often be pro-inflammatory. Ocular surface inflammation can result in reduced tolerance to scleral lens wear. In your glaucoma patients, be mindful to switch your OSD patients to preservative-free formulations when possible.
Keep dosing in mind
Scleral lenses are generally to be applied in the morning and removed at night. Some dosing of glaucoma medications may warrant a midday administration of drops. In such cases, scleral lens removal to administer the drop, followed by reapplication of the lens would be warranted. This can be an inconvenience to the patient and negatively impact wear time as patients may be unable or unwilling to reapply their scleral lens midday.
Practice collaborative care
In your scleral lens patients who may benefit from alternative procedures to manage IOP, be sure to collaborate with their glaucoma specialist to convey your goals. In patients who have appropriate control of their glaucoma but continue to have reduced tolerance to scleral lens wear due to continued use of ophthalmic glaucoma medications, talk to their managing glaucoma specialist about considering alternative procedures like selective laser trabeculoplasty (SLT) or microinvasive glaucoma surgery (MIGS) to reduce the need for drops.
In patients who are planning to have glaucoma surgery, communicate with their surgeon to consider a surgical approach that may yield favorable anatomical endpoints to allow for fitting of a scleral lens following surgery.
Takeaways
As more patients are fit with scleral lenses, it is important to maintain perspective on each patient’s overall ocular health and not solely focus on the fit of the lens. There is much to be learned regarding how a scleral lens may or may not impact IOP in patients with glaucoma. The dynamics of a scleral lens and how it functions on the eye are complex. As the utility and positive impact of scleral lenses grows, more research in the field of scleral lens physiologic function on the ocular surface will provide a better understanding and allow us to better care for our patients.
References
- Barnett M, Courey C, Fadel D, et al. CLEAR - Scleral lenses. Contact Lens Anterior Eye. 2021;44(2):270-288. doi:10.1016/j.clae.2021.02.001
- Huber KK, Maier AKB, Klamann MKJ, et al. Glaucoma in penetrating keratoplasty: Risk factors, management and outcome. Graefe’s Arch Clin Exp Ophthalmol. 2013;251(1):105-116. doi:10.1007/s00417-012-2065-x
- Boso ALM, Gasperi E, Fernandes L, Costa VP, Alves M. Impact of ocular surface disease treatment in patients with glaucoma. Clin Ophthalmol. 2020;14:103-111. doi:10.2147/OPTH.S229815
- Tsai JH, Derby E, Holland EJ, Khatana AK. Incidence and prevalence of glaucoma in severe ocular surface disease. Cornea. 2006;25(5):530-532. doi:10.1097/01.ico.0000220776.93852.d9
- Saade CE, Lari HB, Berezina TL, Fechtner RD, Khouri AS. Topical glaucoma therapy and ocular surface disease: A prospective, controlled cohort study. Can J Ophthalmol. 2015;50(2):132-136. doi:10.1016/j.jcjo.2014.11.006
- Torres T, Ferreira EO, Gonçalo M, Mendes-Bastos P, Selores M, Filipe P. Update on atopic dermatitis. Acta Med Port. 2019;32(9). doi:10.20344/amp.11963
- Beck AD, Freedman SF, Lynn MJ, Bothun E, Neely DE, Lambert SR. Glaucoma-related adverse events in the infant aphakia treatment study: 1-year results. Arch Ophthalmol. 2012;130(3):300-305. doi:10.1001/archophthalmol.2011.347
- Melamed S, Ben-Sira I, Ben-Shaul Y. Corneal endothelial changes under induced intraocular pressure elevation: A scanning and transmission electron microscopic study in rabbits. Br J Ophthalmol. 1980;64(3). doi:10.1136/bjo.64.3.164
