Intraocular Lens Power Calculation for Combined Phaco-vitrectomy Procedures

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

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.

Study Overview

• Status: Unknown
• Conditions: Intraocular Lens Calculation; Combined Phaco-vitrectomy
• Intervention / Treatment: Diagnostic test: Biometry

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 Type: Observational
• Enrollment (Anticipated): 200

Contacts and Locations

Study Locations

• Switzerland
  • Sankt Gallen, Switzerland, 9007
    • Cantonal Hospital of Sankt Gallen

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 99 years (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

• Sampling Method: Probability Sample

Study Population

Patients who undergo a combined procedure with phacoemulsification and pars plana vitrectomy

Description

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 Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Phaco-vitrectomy	Diagnostic test: Biometry; Biometry for phaco-vitrectomy procedures pre- and postoperatively

What is the study measuring?

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

Collaborators and Investigators

• Sponsor: Cantonal Hospital of St. Gallen

Study record dates

Study Major Dates

• Study Start (ANTICIPATED): June 1, 2019
• Primary Completion (ANTICIPATED): June 30, 2020
• Study Completion (ANTICIPATED): September 30, 2020

Study Registration Dates

• First Submitted: February 5, 2019
• First Submitted That Met QC Criteria: February 26, 2019
• First Posted (ACTUAL): February 27, 2019

Study Record Updates

• Last Update Posted (ACTUAL): May 2, 2019
• Last Update Submitted That Met QC Criteria: April 30, 2019
• Last Verified: April 1, 2019

More Information

Terms related to this study

• Keywords: Vitrectomy; Cataract; Phacoemulsification; Biometry; IOL calculation
• Other Study ID Numbers: Phaco-vity-biometry study

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No