Scleral lenses can present with unique challenges. One of these challenges is fogging in the post-lens fluid reservoir – a frustrating problem for practitioners and patients alike. There is minimal tear exchange,1 and the potential for fogging in the post-lens fluid reservoir with scleral lenses.2,3 When debris accumulates between the scleral lens and cornea, fogging may occur after minutes to hours of scleral lens wear.4,5 Fortunately, with advances in scleral lens designs and problem solving techniques, in my practice fogging is less of an issue than it was previously.
The cause of fogging may not be easily identified. Even with ideal scleral lens fitting characteristics and lens care regimen, fogging may still occur. Oftentimes, several changes need to be made to resolve fogging.
Causes of scleral lens fogging may be increased accumulation of tear debris in the lens reservoir, poor tear exchange, increased mucin production from rubbing of the conjunctival tissue, accumulation of protein and lipid deposits on the front surface of the lens, and corneal edema. It is important to differentiate fogging from cornea edema. If rainbows around lights are observed, it is critical to evaluate the cornea for microcystic corneal edema. With corneal edema, removal and reapplication of the scleral lens will not resolve symptoms.
There are three types of post lens fluid reservoir debris, which can occur in combination. Reservoir debris consists of a high concentration of lipids; complications related to tear reservoir clouding are especially common in those with ocular surface disease.6 Management strategies vary depending on the type of debris.
Opaque, white, fluffy, small debris in the post-lens fluid reservoir is termed mucin debris. (Figure 1) Evaluate the scleral lens fit and for any signs of giant papillary conjunctivitis (GPC). Management strategies include eliminating peripheral edge lift by tightening the peripheral curves or adding toric peripheries, reducing wear time, lens removal and reapplication, cleaning the lens with an enzymatic cleaner or a sodium hypochlorite-potassium bromide-based system, and eliminating preservatives in the cleaning or soaking solution. In these cases, hydrogen peroxide based systems work well for disinfection.
Figure 1. White fluffy particulate debris thought to be mucus in the tear reservoir. Image courtesy of Lynette Johns.
There is an association between atopic disease and keratoconus.7 These patients have a diluted milk-like fogging in the post-lens fluid reservoir under the lens. Management strategies include: lens removal and reapplication, evaluating the fitting relationship and reducing excessive edge lift, toric peripheries if edge lift is meridional, topical mast cell stabilizers, or “soft” steroids. Careful monitoring of intraocular pressures and monitoring for infection on patients with steroids is strongly advised.
Meibomian debris is semi-transparent debris that appears like olive oil floating on water. It can be refractile and a yellowish color. It is essential to carefully evaluate and treat the eyelids for any signs of meibomian gland dysfunction or blepharitis. Additionally, reducing excessive tear exchange by altering the peripheral curves can be beneficial for debris management. Lens removal and reapplication is an additional management strategy.
Variations of these three types of debris can occur in combination. Thus, multiple management strategies may need to be used. Fortunately, post-lens reservoir debris is less of a concern than it was previously.
1. Vance KD, Miller W, Bermangson J. Measurement of tear flow in scleral contact lens wearers. Poster presented at: The 94th American Academy of Optometry; Oct 7-10, 2015; New Orleans, LA.
2. Visser ES, Visser R, Van Lier HFF, Otten HM. Modern scleral lenses part II: patient satisfaction. Eye Contact Lens. 2007;33(1):21-25.
3. Barnett, M, Toabe, M. Scleral Lens Care and Handling for Scleral Lenses: Understanding Applications and Maximizing Success. Supplement for Contact Lens Spectrum. October 2016.
4. McKinney A, Miller W, Leach N, Polizzi C, van der Worp E, Bergmanson J. The Cause of Midday Visual Fogging in Scleral Gas Permeable Lens Wearers. Invest Ophthalmol Vis Sci. ARVO E–Abstract, June 2013, Vol.54, 5483.
5. Walker M. Scleral Lenses, Clearing the Fog. I-SITE Online; October 2014.
6. Walker M, Morrison S, Caroline P, et al. Laboratory analysis of scleral lens tear reservoir clouding. Poster presented at: The 2014 Global Specialty Lens Symposium; 2014 Jan; Las Vegas, NV.
7. Harrison RJ, Klouda PT, Easty DL, et al. Association between keratoconus and atopy. Br J Ophthalmol. 1989 Oct;73:816-822.
Dr. Melissa Barnett is a Principal Optometrist at the UC Davis Eye Center in Sacramento, specializing in anterior segment disease and specialty contact lenses. Dr. Barnett is the Immediate Past President of The Scleral Lens Education Society. She lectures and publishes extensively on topics including dry eye, anterior segment disease, contact lenses and creating a healthy balance between work and home life for women in optometry.