Gregory W. DeNaeyer OD FAAO FSLS
Scleral lenses are increasingly being used to manage corneal irregularity and ocular surface disease. Their relatively larger size allows for a more stabilized fit on the sclera while vaulting up over the corneal surface. Typically, success or failure with this lens type hinges on an even bearing distribution that avoids excessive compression or edge lift. However, some patients may have one or more scleral conditions that interfere with a scleral lens fit. Most commonly these obstacles include pinqueculas and conjunctival blebs secondary to trabeculectomy.
An 82-year-old female patient reported for specialty lens fitting of her left eye. She previously had a successful penetrating keratoplasty (Figure 1 - below), but residual irregular corneal astigmatism had left her with 20/300 best corrected visual acuity with manifest refraction.
She also had a moderate conjunctival bleb located near the limbus at the 12 o’clock position from a previous trabeculectomy surgery to manage her glaucoma. Topography showed moderate irregular astigmatism (Figure 2 - below).
Contact lens options for this patient included a corneal (R)GP lens or a scleral lens with a beveled notch. The potential problems with fitting a corneal (R)GP lens included potential mechanical damage from the contact lens edge and lens expulsion if the lens were to get squeezed between the bleb and the patient’s lower lid. With this in mind, a 15mm diagnostic lens with a 47 diopter base curve that had a beveled notch was applied to the eye.
The notch mildly restricted the bleb (Figure 3 - below), and the corneal vault was excessive.
After an over-refraction, a 15mm scleral lens was ordered (Boston XO) with a 44 diopter base curve, power +3.50 and a request to the lab to broaden the beveled notch. The lens was dispensed and the patient was able to achieve her vision potential of 20/50. The scleral notch adequately bypassed the patient’s conjunctival bleb (Figure 4 - below).
The patient was instructed to put the lens on her eye like a puzzle piece so that the notched end was at the 12:00 position. After application and removal training, it was recommended that she fill the lens with nonpreserved carboxymethylcellulose because she had difficulty applying the lens without bubbles when using saline solution. The carboxymethylcellulose is more viscous, making it less likely to spill out of the bowl as the lens is being applied. After 4 months of lens wear, the patient was successfully using the lens without any secondary corneal or bleb complications.
Summary & Discussion
It can be difficult to successfully fit patients who have corneal irregularity and a conjunctival bleb with corneal (R)GP lenses. This is especially true if the bleb is located at the limbus because it can cause the lens to displace or dislodge. Additionally, the bleb is at some risk for damage if the corneal (R)GP lens edge repeatedly bumps into it with on-eye movement. An alternative approach for these patients is fit them with a notched scleral lens.
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.