Study of Clinical Performance of Corneal Topography Measurement Using an Optical Biometer

Lenstar LS 900 Topography

The purpose of this study is to quantify in-vivo repeatability of a new corneal topography measurement mode of an optical biometer, and the clinical performance of measurement in comparison to reference devices.

Study Overview

• Status: Completed
• Conditions: Corneal Topography

• Study Type: Observational
• Enrollment (Actual): 50

Contacts and Locations

Study Locations

• Switzerland
  • Berne, Switzerland, 3010
    • University Hospital Inselspital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Volunteers recruited at University Hospital

Description

Inclusion Criteria:

• 18 years or older

Exclusion Criteria:

• No corneal transplants
• No corneal scar(s)
• No acute infections of the eye
• No weak fixation
• No suspected lack of compliance
• No vulnerable population

Study Plan

How is the study designed?

Number of groups / cohorts

3

Cohorts and Interventions

Group / Cohort
Normal eye; Astigmatism smaller than 1.5 diopters
Large regular astigmatism; Astigmatism of > 1.5 diopters, regular astigmatism.
Large irregular astigmatism; Astigmatism of > 1.5 diopters, irregular astigmatism.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
In-vivo Repeatability of Corneal Topography Measurements With Lenstar LS 900 Topography: Sample Mean of Differences of Mean Power and Sample Mean of Std. Dev of Local Power Differences Between Two Consecutive Measurements	Corneal topography is a measurement of the shape of the anterior cornea. The shape of a cornea can be fully quantified by providing a map of local power. "Diopter" is the unit of refractive power of a lens. In case of the cornea, the power K [diopter] is related to the radius (curvature) R [mm] of the best fitting sphere by the relation K=337.5/R. Here, corneal topography measurements are implemented by the Placido method, i.e. by analyzing the reflection image of a ring-shaped illumination. According to International Standards Organization (ISO) 19980-2012, repeatability of corneal topography is assessed on the central cornea: area with diameter d<=3mm, and middle cornea: 3mm<d<=6mm. "power difference (2 rep. meas.)": sample mean and 95% C.I. of differences of spatial mean of corneal power between two consecutive measurements. "power difference 2 std.dev.": sample mean of twice the deviation of local power differences (two consecutive measurements).	1 day of examination

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Equivalence of Corneal Topography Measurement Between Lenstar LS 900 Topography and Atlas 9000: Sample Mean of Differences of Mean Power and Sample Mean of Std. Dev of Local Power Differences for One Measurement Per Device.	For definition of corneal topography, corneal power in "diopter", areas of evaluation and methods, see outcome 1. This outcome measure aims at testing the equivalence of corneal topography measurement between Lenstar LS 900 Topography (Haag Streit) and Atlas 9000 (Zeiss) by analyzing differences in measurement results for the same eye between both devices. "power difference (2 devices)" is the sample mean and 95% C.I. of differences of spatial mean of corneal power between two devices. This value quantifies systematic differences between devices (e.g. calibration), ignoring local variations of the power measurement. "power difference (2 std.dev.)" is the sample mean of twice the standard deviation of local power differences between measurements with both devices. This value quantifies the spatially resolved agreement of corneal shape measurement of the two devices.	1 day of examination

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Equivalence of Corneal Topography Measurement Between Lenstar LS 900 Topography and Atlas 9000: Sample Mean of Std. Dev. of Local Corneal Elevation Differences for One Measurement Per Device.	For definition of corneal topography, areas of evaluation and methods, see outcome 1 and 2. Corneal elevation refers to the distance between the measured corneal surface and the best fitting sphere, and is given in µm. This outcome measure aims at testing the equivalence of corneal topography measurement between Lenstar LS 900 Topography (Haag Streit) and Atlas 9000 (Zeiss) by analyzing differences in measurement results for the same eye between both devices. "elevation difference (2 std. dev.)" is the sample mean of twice the standard deviation of local corneal elevation differences between measurements with both devices. This value quantifies the spatially resolved agreement of corneal shape measurement of the two devices.	1 day of examination
Equivalence of Keratometry Radius Measurement Between Lenstar LS 900 Topography and Lenstar LS 900: Population Mean of Differences of Keratometry Radius Measurement Between Both Devices.	Keratometry radius refers to the corneal curvature R (see primary measure outcome). In this context, the cornea is approximated by a toric surface which can be characterized by a flat meridian (radius R1) and a steep meridian (radius R2) with an angle of 90 degrees between these meridians. This outcome measure aims at testing the equivalence of keratometry radius measurement between Lenstar LS 900 Topography and Lenstar LS 900 (both Haag Streit) by analyzing differences in measurement results for the same eye between both devices. Reported are: population mean of difference and 95% confidence interval of mean difference for radius of flat meridian (R1) and radius of steep meridian (R2).	1 day of examination
Equivalence of Keratometry Axis Measurement Between Lenstar LS 900 Topography and Lenstar LS 900: Population Mean of Differences of Keratometry Axis Measurement Between Both Devices.	Keratometry axis refers to the axis of the flat meridian of the toric representation of the cornea. For additional information see outcome 4. This outcome measure aims at testing the equivalence of keratometry axis measurement between Lenstar LS 900 Topography and Lenstar LS 900 (both Haag Streit) by analyzing differences in measurement results for the same eye between both devices. Reported are: population mean of difference and 95% confidence interval of mean difference for axis of flat meridian.	1 day of examination

Collaborators and Investigators

• Sponsor: Haag-Streit AG
• Collaborators: University Hospital Inselspital, Berne
• Investigators: Principal Investigator: Beatrice Frueh, Prof. Fr., University Hospital Inselspital, Berne

Study record dates

Study Major Dates

• Study Start: June 1, 2013
• Primary Completion (Actual): July 1, 2013
• Study Completion (Actual): July 1, 2013

Study Registration Dates

• First Submitted: May 21, 2013
• First Submitted That Met QC Criteria: May 23, 2013
• First Posted (Estimate): May 24, 2013

Study Record Updates

• Last Update Posted (Estimate): June 5, 2014
• Last Update Submitted That Met QC Criteria: May 13, 2014
• Last Verified: May 1, 2014

More Information

Terms related to this study

• Other Study ID Numbers: HS-LS900-TOPO-01