Contact Lens Spectrum Supplements

Special Edition 2017

Contact Lens Spectrum

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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 7 c l s p e c t r u m . c o m 70 CONT ACT LENS CASE REPOR TS L U C I A N O B A S TO S and the corneal topography still presented irregular astigmatism, especially OS. Figure 1 shows the patient's current corneal topogra- phy; figure 2 shows Scheimpflug views of the corneal profiles in dif- ferent contrast settings. Refining the Fit Fitting scleral lenses in this case helped us to overcome difficulties normally found in post-surgical and irregular corneas. We have improved the design of his scleral lenses over the last few years. Our objective is to always refine the lens The posterior haptic is quadrant- specific and is calculated by obser- vation. We do not have an instru- ment to measure scleral topogra- phy, but by evaluating specific trial lenses, we are able to achieve the best combination of splines. We have found that if the differences at the quadrants are small, and if there are no scleral obstacles, the lens can be applied in any position and will rotate to the proper orien- tation in a matter of minutes, espe- cially when the lens has most of the liquid lens reservoir. Although most of the scleral lens designs that we have seen use a minimum center thickness of 0.25mm, we use less than 0.20mm in powers greater than –6.50D and have experienced no problems with flexure that would induce residual cylinder or with lens adesion from negative pressure. One interesting fact in this partic- ular case was that we were able to fit the same lens design despite the dif- ferent corneal topography and treat- ment. The final scleral lens param- eters were OD 42.50D base curve, to achieve the best anterior eye and corneal alignment. We used a 19.4-mm diameter full scleral lens in a design that provides a larger landing zone to help alleviate the pressure over the conjunctiva. Figure 3 shows the cross-section view of both lenses. This scleral lens design has a multi-aspheric posterior curve that allows a cus- tomized vault, with a spline haptic developed to achieve the best land- ing zone. It also features ventilating invisible channels to allow tears or preservative-free lubricant to enter and slowly renew the tear reservoir. CUSTOMIZED SCLERAL FITTING POST-PTK AND CORNEAL RINGS A 33-year-old male patient who was diagnosed with bi- lateral keratoconus at puberty came to the Instituto de Olhos Dr. Saul Bastos in 2008. He had a previous his- tory of failure in achieving an ideal GP lens fit and had undergone intrastromal ring implants OS, with subse- quent extrusion of the superior segment and infection. We prescribed aspheric intralimbal GPs that he wore until 2011, when we observed significant ectasia progression in both eyes. We then fit 17.5mm scleral lenses, which provided excellent results. In 2013, the patient underwent penetrating keratoplasty OD and intracorneal ring implants with femtosecond laser. Despite the better anteri- or corneal profile obtained with the procedures, visual acuity was still poor, Figure 1. (A) Post-corneal surgery topography OD; (B) Post-corneal surgery topography OS. B

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