Contact Lens Spectrum Supplements

Special Edition 2017

Contact Lens Spectrum

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Page 40 of 75

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 7 39 stand the difference. I recommend you follow the same principles covered for bitorics and determine the BCR and powers for each meridian as before and relate those numbers to the laboratory. A BST should be performed as a saddle fit. For both bitoric and BST designs, look for the same fitting relationships as you did before: good positioning and appropriate lid interaction, an even distribution of NaFl under the lens, and appropriate edge clearance. If these are not ideal, discuss necessary changes with your laboratory consultant. If the lens was designed correctly, the cylinder correction provided to the patient will be correct and a SOR should be all that is needed. If acuity GP SPHERICALS AND TORICS is not as expected, a SCOR can help the laboratory refine the powers. SUMMARY Corneal GPs are still a great option for patients with normal corneas. Hopefully, this refresher course will in- spire you to consider this option more frequently. Great vision for your patients awaits! CLS Dr. Jackson is a professor at Southern College of Optometry where he works in the Advanced Contact Lens Service, teaches courses in contact lenses, and performs clinical research. You can reach him at REFERENCES 1. Young G. Ocular sagittal height and soft contact lens fit. J Br Contact Lens Assoc. 1992;15:45-49. 2. Zheng F, Caroline P, Kojima R, Lampa M, Kinoshita B, Andre M. Corneal Elevation Differences in the Initial Selection of Therapeutic Scleral Contact Lenses. Poster presented at: Global Specialty Lens Symposium; 2015; Las Vegas, NV. 3. Achong-Coan R, Caroline P, Kinoshita B, et al. How Do Normal and Keratoconic Eyes Differ in Shape? Poster presented at: Global Specialty Lens Symposium; 2012; Las Vegas, NV. 4. Kinoshita B, Caroline P, Morrison S, Lampa M, Kojima R, Andre M. Corneal Toricity and Scleral Asymmetry — Are They Related? Poster presented at: Global Specialty Lens Symposium; 2016; Las Vegas, NV. Dr. Lampa is an associate professor at Pacific University College of Optometry, where he is involved with specialty contact lens fitting, contact lens instruction, and clinical research. He is a consultant/ advisor to SpecialEyes and has received honoraria or travel expenses from Alcon, Contamac, CooperVision, Johnson & Johnson, and Valley Contax. Dr. Kinoshita is an associate professor and serves as the director of the Pacific Eye Clinic in Forest Grove and as an instructor in the contact lens courses. She is a Fellow of the American Academy of Optometry (AAO) and a Diplomate in the Cornea, Contact Lens and Refractive Technologies Section of the AAO. She lectures and conducts research on topics related to contact lens complications and specialty contact lens fitting and design. the dioptric power from the keratometer or axial display topography map. When fitting a scleral lens, we see that the scleral shape is highly asymmetric and confirms the presence of variations in elevation and curvature, but can we describe it in the same terms as corneal height differences? As contact lens designs are developed and intended to fit out onto a broader portion of the sclera, it may be necessary to image both the cornea and the sclera in an attempt to optimize the asymmetric scleral shape. Some scleral lens designs have a predetermined asymmetry on the haptic portion of the lens to better align the sclera. In one design, an ocular impression is used to determine the exact contour of the cornea and the sclera. It is important that we all gain from these insights when designing and prescribing custom contact lenses for our patients to optimize vision, fit, and comfort, par- ticularly those who need them the most, so that they can thrive in their activities of daily living and we may all share in the reward of satisfying their visual needs. CONCLUSION Good contact lens practice involves considering all options for your patients, including lifestyle, vision needs, and anatomical features. Recognizing that some patients will fall outside the norm will help to expand your contact lens practice and potentially minimize con- tact lens dropout. Although there is still a lot that we do not know, we have an industry and profession that is constantly trying to improve and innovate, so keep your eyes open for what is on the horizon. CLS Continued from p.32 Figure 4. An optic section will show the thickness of the soft contact lens relative to the corneal thickness. The average corneal thickness in both photos is 0.550 mm. Figure 4A is a silicone hydrogel lens with a thickness of 0.07 mm. Figure 4B is a custom soft lens with a thick- ness of 0.40 mm.

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