Bypassing Scleral Obstacles
Gregory W. DeNaeyer OD FAAO FSLS
The rigid nature of scleral lenses can cause fitting challenges when scleral obstacles, such as pingueculas or conjunctival blebs, are proximal to the corneal limbus. Corneo-scleral topography can be used to map out the location, dimensions and sagittal height of these obstacles. A scleral notch or a customized haptic vault can be designed from topography to bypass or vault the obstacle to successfully fit a scleral contact lens.
A 64-year-old female patient with a history of keratoconus and subsequent penetrating keratoplasty of her right eye had reduced best-corrected visual acuity secondary to corneal irregularity. Her refraction was +4.00 -4.00 X 072, with count fingers vision. The patient also was diagnosed with glaucoma and had a previous trabeculectomy. She formerly wore a notched scleral lens for her right eye.
The patient was being refit after recent express shunt surgery (Fig 1, above).
Ocular Surface Topography
Corneo-scleral topography was performed, and the scleral elevation map was evaluated (Figure 2, below left). The elevated topographical section secondary to the bleb was cut out (Figure 3, below right), and software was used to design a back-surface-toric scleral with a 7 mm X 2 mm notch. Note that an accurate measurement of the sclera for lens fitting requires the removal of the elevated area associated with the conjunctival bleb.
The sagittal height plots shown in Figure 4 (below) demonstrate significant scleral toricity that is uniformly matched with a back-surface-toric scleral lens that improved the patient’s visual acuity to 20/40.
Corneo-scleral topography was also used to create an additional lens that had an area of customized edge lift to vault the conjunctival bleb (Figures 6 and 7, below). After wearing both versions, the patient reported that the notched lens and the lens with a customized edge vault were both equally comfortable. No fitting complications resulted from either design. Both lenses were stabilized with back-surface toricity.
Corneo-scleral topography can be used to successfully map the sclera, including obstacles that can interfere with scleral lens fitting. A scleral lens with a notch to bypass the obstacle can be designed after removing the obstacle from the elevation map (Fig 8, below).
If the practitioner would prefer to vault the obstacle with a customized edge lift, the obstacle’s dimension (including sagittal height) can be used to manufacture a customized edge vault to avoid compression (Fig 9, below). For this case, both strategies were successful for this patient, and she continues to wear the scleral lens with customized edge vault.
Greg DeNaeyer is a graduate of The Ohio State University College of Optometry. He completed a hospital based residency at the Columbus VA Medical Center. Dr. DeNaeyer practices at Arena Eye Surgeons with an emphasis on specialty contact lenses.
Dr. DeNaeyer was a co-founder and is the past president 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. Dr. DeNaeyer has lectured internationally on specialty contact lenses and was the 2012 GPLI practitioner of the year.
Currently his primary research is focused on scleral lens design.