Maximum permissible torsional misalignment in aberration-sensing and wavefront-guided corneal ablation

Abstract

The tolerance range for torisional alignment in wavefront-guided higher-order corrections depends on the amount of original optical error in each eye. Rough centration based on the surgeon's judgment may not be accurate enough to achieve significantly improved optical quality in a high percentage of treated eyes.

Factors affecting the change in lower-order and higher-order aberrations after wavefront-guided laser in situ keratomileusis for myopia with the Zyoptix 3.1 system

“…These findings suggest that, to a large extent, the change in HOA after wg-LASIK is subject to other variables such as fluctuations in the fluence, imprecision of registration, and biomechanical effects as a result of flap creation and ablation. 10,11,16,30,31 In a recent study, Porter et al 32 show that pupil misalignment of the OZ during LASIK surgery occurred frequently. Other factors that were not examined by the model are short-term wavefront fluctuations during measurement due to tear-film breakup and accommodation, 33,34 as shown for the Zywave sensor in another study.…”

Influence of pupil and optical zone diameter on higher-order aberrations after wavefront-guided myopic LASIK

“…There are many possible reasons for this variance: the wavefront-guided algorithm, attempted SE, decentration of the OZ relative to the optical axis, individual biomechanical response of the cornea, and local differences of laser beam fluence. 28,[33][34][35][36][37][38] Also, different biomechanical and wound healing responses in dependence from the absolute OZ diameter should be expected. A detailed analysis of these factors seems necessary but is beyond the scope of this investigation and will be addressed in an upcoming study.…”

Treatment Strategies and Clinical Outcomes of Aspheric Surgery for Astigmatism Using the SCHWIND Amaris Platform

“…Measuring rotation when the patient is upright 36 to when the refractive treatments are performed with the patient supine may lead to ocular cyclotorsion, 37 , 38 resulting in mismatching of the applied versus the intended profiles 39 , 40 . Recently, some equipment can facilitate measurement of and potential compensation for static cyclotorsion occurring when the patient moves from upright to the supine position during the procedure 41 , quantifying the cyclorotation occurring between wavefront measurement and laser refractive surgery 42 and compensating for it 43 , 44 , 45 .…”