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OK lenses for myopia induce significant structural and optical changes particularly in the central epithelium after 15 days or 1 month of wear. The central corneal epithelium responds to OK wear by undergoing significant epithelial cell shape and size alterations with no effects, however, on the cells of the corneal endothelium or the corneal stroma. Peripheral corneal thickness increased with respect to baseline values. These findings suggest that the corneal epithelium is the principal structure affected by the mechanical forces exerted by the OK lenses.

Objectives To describe the past 20 years' correction modalities for keratoconus and their visual outcomes and possible complications. Methods A review of the published literature related to the visual outcomes and possible complications in the context of keratoconus management using nonsurgical procedures for the last 20 years (glasses and contact lenses) was performed. Original articles that reported the outcome of any correction modalities of keratoconus management were reviewed. Results The most nonsurgical procedure used on keratoconus management is the contact lens fitting. Soft contact lenses and soft toric contact lenses, rigid gas-permeable contact lenses, piggyback contact lens system, hybrid contact lenses, and scleral and corneoscleral contact lenses form the contemporary range of available lens types for keratoconus management with contact lenses. All of them try to restore the vision, improve the quality of life, and delay surgical procedures in patients with this disease. Complications are derived from the intolerance of using contact lens, and the use of each depends on keratoconus severity. Conclusions In the context of nonsurgical procedures, the use of contact lenses for the management of keratoconic patients represents a good alternative to restore vision and improve the quality of live in this population.

Q-values varied according to the refractive properties examined. However, the relationship between refractive state and corneal asphericity was found to be determined more by the geometric properties of the eye (corneal power and axial length) than by manifest refraction.

Abstract:Purpose: To assess the changes on the ocular surface parameters with ageing. Methods Conclusions:These results suggest that the ocular surface conditions change with ageing. Many of these ocular surface parameters could be relevant for contact lens fitting.

46Objective: to assess the intra-rater repeatability of the measurements of tear meniscus 47 height (TMH), noninvasive Keratograph tear breakup time (NIKBUTs) and ocular redness 48 measurements obtained with the Keratograph 5M (K5M) in a sample of soft silicone 49 hydrogel CL wearers over 15 days. 50 Methods: prospective study over two consecutive weeks. Three measurements of TMH, 51 NIKBUTs (NIKBUT-first and NIKBUT-average) and ocular redness were obtained in different 52 sessions; the first day (baseline, at 8 hours of wear, and after lens removal) and the last day 53 of wear -15th day (at 8 hours of wear and after lens removal). The repeatability of 54 measurements were assessed by two intraclass correlation coefficient (ICC) forms; single 55 measurement [ICC (2,1)] and multiple measurements (k=3) [ICC (2, k)]. 56 Results: The repeatability of baseline TMH [ICC (2,1) >0.90 ; CR=0.06 mm] and after and 57 during CL wear [ICC (2,k) >0.90 ; CR≤0.07 mm] were excellent. The repeatability of baseline 58 NIKBUT-average [ICC (2,k) =0.89 (0.82 to 0.93) ; CR=6.07 sc] was maintained after CL 59 removal, but was poorer during CL wear. The repeatability of baseline NIKBUT-first [ICC (2,k) 60 =0.80 (0.69 to 0.87) ; CR=8.74 sc] was maintained after CL removal and during CL wear at 61 moderate-good level. 62 Conclusions: Intra-rater repeatability of TMH, NIKBUTs and ocular redness performed by 63 K5M after CL wear remain stable when three measurements are performed. However, intra-64 rater repeatability during CL wear decreased only for NIKBUT average and was not affected 65 by time of use (15 days).66 67

A long period of OK reduces ACD and AL and changes PRCC.

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