Contact Lens Spectrum
Issue link: https://clssupplements.epubxp.com/i/740958
c l s p e c t r u m . c o m C O N T A C T L E N S S P E C T R U M S P E C I A L E D I T I O N 2 0 1 6 55 CONT ACT LENS CASE REPOR TS LY N E T T E K . J O H N S, O D, FA AO, FS L S IMPROVING PATIENT COMFORT A 55-year-old male with long-standing keratoconus com- plained of discomfort with his current monovision hybrid lenses, especially at the end of the day. He achieved 20/25 OD and 20/70 OS at distance (over-refraction -1.00 yielded 20/40 + ) and 20/30 at near. He re- moved hi s lenses multiple times a day "to get them more comfortable." He wore the lenses at most 12 hours, but stated he wanted to take them out hours earlier. He also had circumlimbal neovascularization OU. He was refit into Zenlens scleral lenses. The initial diameter of the diagnostic lens is selected by measuring the horizon- tal visible iris diameter (HVID). If the HVID is less than 11.8 mm, the 16.0-mm diagntic lens is selected. His HVID was 12.0 mm in each eye; however, he had very focal and elevated nasal pin- gueculae. The 16.0-mm lens was chosen to avoid the pinguecula. Zenlens has two shape configura- tions. The prolate shape is selected for keratoconus, as prolate means it is a steeper central curve relative to the flatter periphery. The oblate shape is similar to a reverse geom- etry lens, in which the periphery is steeper than the central base curve. Although this diagnostic lens was not optimal, we learned that: 1) Central apical clearance was present; 2) The prolate shape did not provide peripheral corneal clearance; 3) The advanced pe- ripheral system, or landing zone, needed to be tightened; 4) More edge lift along the vertical merid- ian suggested a with-the-rule scleral toricity pattern; and 5) The diam- eter did not interfere with the pin- guecula and provided sufficient corneal vaulting. The oblate shape with similar sag- ittal depth (4,700 microns/9.0 mm) demonstrated central and periph- eral corneal clearance. Limbal con- tact was present, and the periphery looked the same as the previous pro- late diagnostic lens. Over-refraction was performed, and the lens param- eters were determined. Both the sagittal depth and lim- bal clearance can be raised and The first diagnostic lens was applied OD with a sagittal depth of 4,800 microns, base curve of 7.1 mm, and standard periphery. There was apical clearance, but the lens contacted the midperipheral cornea. There was also significant edge lift around the periphery, pre- dominantly in the vertical merid- ian, and the edge did not impinge against the nasal pinguecula. Figure 1. Nasal view of the final lens OD. Figure 2. Temporal view of the final lens OD. U F P. 0 2 8 8 . U S A . 1 6