![]() It is important to note that impingement and compression can occur concurrently. Compression occurs along the inner scleral landing curves and causes a whitening of the conjunctival vessels under the lens ( Figure 2). This cuts off circulation to the conjunctival vessels.Ģ. Impingement occurs along the outermost curve of the lens, causing the lens to dig into the conjunctiva. Blanching can be further broken down into 2 categories:ġ. Patients commonly report the following after removal: discomfort often extending into the next day, rebound hyperemia, and/or an impression ring. This is caused by localized pressure on the conjunctiva and can be quadrant specific, meridional, or circumferential. Here are some of the most common fitting challenges. In reality, although the actual fitting of scleral lenses is simple, troubleshooting problems is more challenging. In a perfect world, following these 4 steps would provide each patient with an exact fit and exceptional vision ( Figure 1). ![]() Limbal clearance is equally as important as apical clearance. Most manufacturers recommend 100 to 250 μm of apical clearance after the lens has settled for approximately 30 minutes. Once the starting diagnostic lens is placed on the eye, evaluate the apical clearance. When in doubt, choose a lens from the middle of the fitting set. Once the appropriate diameter and design have been selected, choose a starting lens recommended by the manufacturer based on the patient’s corneal condition or keratometry values. This can be measured manually with an HVID ruler or slit lamp beam or obtained from metrics provided by a topographer. In this case, try both designs and determine which is a better overall fit based on fitting guidelines 2 through 4.Ĭhoosing the appropriate diameter should be guided by the patient’s horizontal visible iris diameter (HVID). On occasion, topography reveals a corneal pattern that does not clearly fit into either category (eg, post transplant). An oblate design is ideal for patients who have had refractive surgery (eg, LASIK, photorefractive keratectomy, or radial keratotomy). A prolate design is ideal for regular corneas or patients with corneal ectasias (eg, keratoconus and pellucid marginal degeneration). Choose a diagnostic lensĬhoosing the correct diagnostic lens is crucial and includes 2 key steps: selecting proper design and selecting diameter. When fitting empirically-regardless of the manufacturer-all scleral lenses follow the same 4 basic guidelines. As scleral lenses have become commonplace in many practices, manufacturers have created simple fitting guides.
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