Intraocular Lens Power Calculation for Combined Phaco-vitrectomy Procedures

• Conditions: Combined Phaco-vitrectomy; Intraocular Lens Calculation
• Interventions: Diagnostic Test: Biometry

• Registration Number: NCT03856346
• Lead Sponsor: Cantonal Hospital of St. Gallen

Brief Summary

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

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 Timeline

• Study First Submitted: 2019-02-05
• Study First Submitted QC: 2019-02-26
• Study First Posted: 2019-02-27
• Status Verified: 2019-04
• Last Update Submitted: 2019-04-30
• Last Update Posted: 2019-05-02
• Study Start: 2019-06-01
• Primary Completion: 2020-06-30
• Study Completion: 2020-09-30

Recruitment & Eligibility

• Status: UNKNOWN
• Sex: All
• Target Recruitment: 200

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

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
Phaco-vitrectomy	Biometry	-

Primary Outcome Measures

Name	Time	Method
Refractive prediction error (measured by subjective refraction, in diopters)	6 weeks postoperatively	postoperative actual subjective refraction minus preoperative planned refraction in spherical equivalence (in diopters)
Absolute prediction error (measured by subjective refraction, in diopters)	6 weeks postoperatively	absolute value of the difference between postoperative actual refraction and preoperative planned refraction (in diopters)
Changes in Axial Length (measured by biometry, in milimeters)	6 weeks postoperatively	Change of axial length postoperatively (in milimeter)
Changes in corneal curvature (measured by corneal topography, in diopters)	6 weeks postoperatively	change in corneal curvature (in diopters)

Trial Locations

Locations (1)

Cantonal Hospital of Sankt Gallen; 🇨🇭 Sankt Gallen, Switzerland