The aim of the study is to evaluate the degree of refractive error postoperatively in combined procedures and to calculate a new constant in order to improve current state of the art biometry calculations.
The IOL power calculation in combined phaco-vitrectomy has been performed similar to that in cataract surgery alone. In patients who undergo combined phaco-vitrectomy, deviations in refractive outcomes may be observed because of possible errors in measurement of axial length, changes in the properties of the vitreous cavity after removal of the vitreous, or intraocular tamponade. Most of the previous studies have reported variable degrees of myopic shift after phaco-vitrectomy for diabetic retinopathy, epiretinal membrane, and macular hole. Furthermore, use of intraoperative gas may increase further the risk of anterior displacement of the intraocular lens which may induce a higher myopic shift. However, these publications did not provide any quantification of the spherical deviations nor calculate any specific constant in order to improve currents state of art biometry calculations.
Study Type
OBSERVATIONAL
Enrollment
200
Biometry for phaco-vitrectomy procedures pre- and postoperatively
Cantonal Hospital of Sankt Gallen
Sankt Gallen, Switzerland
Refractive prediction error (measured by subjective refraction, in diopters)
postoperative actual subjective refraction minus preoperative planned refraction in spherical equivalence (in diopters)
Time frame: 6 weeks postoperatively
Absolute prediction error (measured by subjective refraction, in diopters)
absolute value of the difference between postoperative actual refraction and preoperative planned refraction (in diopters)
Time frame: 6 weeks postoperatively
Changes in Axial Length (measured by biometry, in milimeters)
Change of axial length postoperatively (in milimeter)
Time frame: 6 weeks postoperatively
Changes in corneal curvature (measured by corneal topography, in diopters)
change in corneal curvature (in diopters)
Time frame: 6 weeks postoperatively
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