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مقاله
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Abstract
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Title:
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IOL Power Calculation and Post-Op Refraction in a Post-RK Patient With Help of Pentacam : A Case Report
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Author(s):
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Ghandehari-Motlagh Mohammad
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Presentation Type:
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Poster
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Subject:
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Cornea and Anterior Segment
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Others:
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Presenting Author:
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Name:
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Mohammad Ghandehari Motlagh
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Affiliation :(optional)
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Optometrist (Sadra Eye Surgery Center), Isfahan- Iran
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E mail:
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oculist233@aol.com
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Phone:
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03116689608
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Mobile:
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09132000891
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Purpose:
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P=n-1/R:as a Famous formula is an explanation for common surprises in IOL power calculations of post-RK cases due to keratometery errors .Due to the smaller optical zone of a post-RK cornea than post-PRK one,and on the other, keratometers can measure only 3-4 mm paracentral anterior portion of the cornea(not central),then IOL master consider the steeper paracentral K-readings for the flat central cornea. In post-RK corneas 3-4mm paracentral is steeper than central and so underestimated IOL power and a post-op hyperopia will be expected. Then we have to use imaging devices especially Pentacam for small optical zones(even 2mm) for an accurate k-reading.
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Methods:
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Ocular biometry(IOL master 500)was done for a 30 yrs/old post-RK cataractous patient and so I couldn’t rely on k-redings of IOL master. So imaging with Pentacam was done and Power Distribution Display/ 2mm Total Refractive Power, were my k-readings entered in IOL master. Axial lengths:OD=26.56 and OS=26.81 and so the selected formulas were Haigis and SRK/T.Selected target refraction= -0.25.Average K-readings with IOL master were 37.3 and 36.But in 2mm optical zone with pentacam was 36.45 and 35.10.
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Results:
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Post-op residual refractive error = -0.25 D.
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Conclusion:
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Pentacam is a valuable instrument for IOL power calculations in post-RKs with small optical zone of RK.
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Attachment:
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