Gregory W. DeNaeyer OD FAAO FSLS
A well-fit scleral contact lens should hold a fluid reservoir without any bubbles between the lens and the ocular surface. For non-fenestrated scleral lenses, the presence of bubbles is usually secondary to application error. This can occur if not enough saline is added pre-application or if some of the saline spills out during application. A fenestration, which is a 1mm hole that is drilled into the mid-peripheral section of a scleral lens, can sometimes induce bubble formation within the fluid reservoir. Small (less than 2mm) bubbles that aren’t fixed in position are usually of no consequence. Larger bubbles (4mm or larger) can reduce the negative pressure under the lens, which leads to lens movement and secondary discomfort. Bubbles of any size that enter the visual axis can disrupt visual acuity. Any bubbles that are fixed in location can lead to epithelial depression and desiccation.
A 67-year-old patient reported for a specialty contact lens fitting. Her left eye had previously undergone a full thickness corneal transplant. The development of corneal irregularity limited her best-corrected spectacle correction to 20/200. She was successfully fit with a corneal-scleral lens in the following parameters: BC 7.67mm, Dia 14.5mm and power -1.75. The lens was manufactured in Paragon HDS 100 with 1 mid-peripheral fenestration. The lens adequately vaulted the cornea and provided vision of 20/25. Over the course of a 4-year time period, a persistent bubble (Figure 1) was observed superior-temporally despite filling the lens with solution pre-application. This resulted in a secondary epithelial impression (Figure 2).
She also complained that the lens irritated her eye, which limited her wear time to 3-4 hours. The patient was asked to discontinue lens wear and to return for a refit. A diagnostic mini-scleral lens with sagittal depth of 4.6mm, Dia 15.8mm, and no fenestration successfully fit to the patient’s eye (Figure 3). A final power of -4.00 gave the patient 20/20 vision, and her wear time increased to 5-6 hours/day.
Summary and Discussion
In non-fenestrated lenses, small transient bubbles are most often secondary to application error. These bubbles are rarely of any consequence as long as the patient is comfortable and has good vision. Bubbles that result from fenestrated lenses can be more persistent and cause epithelial changes including epithelial depression, desiccation and corneal thinning. If this is the case, the best management strategy is to refit the patient into a non-fenestrated scleral lenses.
Greg DeNaeyer is a 1998 graduate of The Ohio State University College of Optometry. He completed a hospital based residency at the Columbus VA Medical Center. Greg joined Arena Eye Surgeons in 1999 and is currently the Clinical Director. His primary interest is specialty contact lenses.
Greg is a boardmember of the Scleral Lens Education Society and is a Fellow of the American Academy of Optometry. He is a contributing editor for Contact Lens Spectrum and a contributor to Review of Cornea and Contact Lenses and Optometric Management. Currently his primary research is focused on profilometer designed scleral contact lenses, scleral lenses that correct higher order aberrations, and topical drug delivery devices. He has consulted for Visionary Optics, Essilor, Inspire Pharmaceuticals, B+L, and Aciont.