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The relation between alignment of exam and astigmatic axis and value

Poster Details

First Author: C.Arce BRAZIL

Co Author(s):                  

Abstract Details


To determine how different is the axis and the value of astigmatism of the cornea with different alignment of exams


: Private Eye Clinic


Dual Scheimpflug and Placido anterior segment tomographer was used to determine the amount and axis of astigmatism from the anterior and posterior axial curvature maps, and from the whole cornea by ray tracing with exams aligned to the first image of Purkinge and to the pupil center


Pupil center and the first image of Purkinge reflected on the cornea are the two main referential marks used in cataract and refractive surgery. Although value and axis of corneal astigmatism is assumed to be similar in both alignments, an important number of cases may also have variation in axis between 5° to 40°


Alignment of exams should be the same used in surgery. Preoperative assessment of axis and value of corneal astigmatism using both referential marks used in the surgical field (first image of Purkinge and pupil center) should improve the refractional results after cataract and refractive surgery. Important postoperative errors in refractional cylinder and axis may happen due to misalignment of toric IOLs and laser corneal surgery. On the other hand, toric IOLs should have better result when axis is the same in different alignments. Devices that have different alignment of exams may produce different data.

Financial Disclosure:

... receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented, ... travel has been funded, fully or partially, by a company pr

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