Intraocular Lens Power Calculation for Combined Phaco-vitrectomy Procedures

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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Intraocular Lens Power Calculation for Combined Phaco-vitrectomy Procedures: Calculation of a New Constant for Biometry IOL-formulas

Conditions
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Intraocular Lens Calculation, Combined Phaco-vitrectomy

Intervention / Treatment
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* Diagnostic Test: Biometry


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients who undergo a combined procedure with phacoemulsification and pars plana vitrectomy Exclusion Criteria: Sulcus fixation of the IOL, sulcus suture of the IOL, or intra-scleral IOL fixation because of intraoperative posterior capsule rupture corneal disease, such as keratoconus, that interfered with refractive results IOL implantation with a toric IOL or multifocal IOL History of previous vitrectomy or corneal transplantation Other coexisting ocular disease such as proliferative diabetic retinopathy, advanced age-related macular degeneration, uveitis, acute retinal necrosis, Coat's disease, proliferative vitreous retinopathy, or trauma Intraocular tamponade using silicon oil

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 99 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Phaco-vitrectomy<br> | Diagnostic Test: Biometry<br>* Biometry for phaco-vitrectomy procedures pre- and postoperatively<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Refractive prediction error (measured by subjective refraction, in diopters) | postoperative actual subjective refraction minus preoperative planned refraction in spherical equivalence (in diopters) | 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) | 6 weeks postoperatively | 
| Changes in Axial Length (measured by biometry, in milimeters) | Change of axial length postoperatively (in milimeter) | 6 weeks postoperatively | 
| Changes in corneal curvature (measured by corneal topography, in diopters) | change in corneal curvature (in diopters) | 6 weeks postoperatively | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Vitrectomy, Phacoemulsification, Biometry, IOL calculation, Cataract