Trial Outcomes & Findings for Study of Clinical Performance of Corneal Topography Measurement Using an Optical Biometer (NCT NCT01861925)

NCT ID: NCT01861925

Last Updated: 2014-06-05

Results Overview

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).

• Recruitment status: COMPLETED
• Target enrollment: 50 participants
• Primary outcome timeframe: 1 day of examination
• Results posted on: 2014-06-05

Participant Flow

Participant milestones

Measure	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.
Overall Study STARTED	34	8	8
Overall Study COMPLETED	34	8	8
Overall Study NOT COMPLETED	0	0	0

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

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

Baseline characteristics by cohort

Measure	Normal Eye n=34 Participants Astigmatism smaller than 1.5 diopters	Large Regular Astigmatism n=8 Participants Astigmatism of \> 1.5 diopters, regular astigmatism.	Large Irregular Astigmatism n=8 Participants Astigmatism of \> 1.5 diopters, irregular astigmatism.	Total n=50 Participants Total of all reporting groups
Age, Continuous	38.8 years STANDARD_DEVIATION 9.8 • n=5 Participants	36.4 years STANDARD_DEVIATION 9.0 • n=7 Participants	32.7 years STANDARD_DEVIATION 8.2 • n=5 Participants	37.4 years STANDARD_DEVIATION 9.5 • n=4 Participants
Age, Categorical <=18 years	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Age, Categorical Between 18 and 65 years	34 Participants n=5 Participants	8 Participants n=7 Participants	8 Participants n=5 Participants	50 Participants n=4 Participants
Age, Categorical >=65 years	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Sex: Female, Male Female	13 Participants n=5 Participants	2 Participants n=7 Participants	0 Participants n=5 Participants	15 Participants n=4 Participants
Sex: Female, Male Male	21 Participants n=5 Participants	6 Participants n=7 Participants	8 Participants n=5 Participants	35 Participants n=4 Participants
Region of Enrollment Switzerland	34 participants n=5 Participants	8 participants n=7 Participants	8 participants n=5 Participants	50 participants n=4 Participants

PRIMARY outcome

Timeframe: 1 day of examination

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).

Outcome measures

Measure	Normal Eye n=34 Participants Astigmatism smaller than 1.5 diopters	Large Regular Astigmatism n=8 Participants Astigmatism of \> 1.5 diopters, regular astigmatism.	Large Irregular Astigmatism n=8 Participants Astigmatism of \> 1.5 diopters, irregular astigmatism.
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 power difference (2 rep. meas.), central cornea	-0.014 diopters Interval -0.062 to 0.034	0.053 diopters Interval -0.061 to 0.167	-0.120 diopters Interval -0.392 to 0.153
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 power difference (2 rep. meas.), middle cornea	-0.029 diopters Interval -0.09 to 0.033	0.015 diopters Interval -0.149 to 0.179	-0.089 diopters Interval -0.351 to 0.174
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 power difference (2 std.dev.), central cornea	0.77 diopters 95% C.I. of Std.Dev. not required by ISO 19980-2012	0.74 diopters 95% C.I. of Std.Dev. not required by ISO 19980-2012	1.36 diopters 95% C.I. of Std.Dev. not required by ISO 19980-2012
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 power difference (2 std.dev.), middle cornea	0.72 diopters 95% C.I. of Std.Dev. not required by ISO 19980-2012	0.69 diopters 95% C.I. of Std.Dev. not required by ISO 19980-2012	1.06 diopters 95% C.I. of Std.Dev. not required by ISO 19980-2012

SECONDARY outcome

Timeframe: 1 day of examination

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.

Outcome measures

Measure	Normal Eye n=34 Participants Astigmatism smaller than 1.5 diopters	Large Regular Astigmatism n=8 Participants Astigmatism of \> 1.5 diopters, regular astigmatism.	Large Irregular Astigmatism n=8 Participants Astigmatism of \> 1.5 diopters, irregular astigmatism.
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. power difference (2 devices), central cornea	0.044 diopters Interval -0.023 to 0.11	0.012 diopters Interval -0.039 to 0.063	0.160 diopters Interval -0.57 to 0.889
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. power difference (2 std.dev.), central cornea	0.79 diopters 95% C.I. of Std.Dev. not required by ISO 19980-2012	0.77 diopters 95% C.I. of Std.Dev. not required by ISO 19980-2012	2.49 diopters 95% C.I. of Std.Dev. not required by ISO 19980-2012
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. power difference (2 devices), middle cornea	0.070 diopters Interval -0.004 to 0.144	0.038 diopters Interval -0.058 to 0.134	-0.083 diopters Interval -0.701 to 0.536
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. power difference (2 std.dev.), middle cornea	0.76 diopters 95% C.I. of Std.Dev. not required by ISO 19980-2012	0.72 diopters 95% C.I. of Std.Dev. not required by ISO 19980-2012	1.56 diopters 95% C.I. of Std.Dev. not required by ISO 19980-2012

OTHER_PRE_SPECIFIED outcome

Timeframe: 1 day of examination

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.

Outcome measures

Measure	Normal Eye n=34 Participants Astigmatism smaller than 1.5 diopters	Large Regular Astigmatism n=8 Participants Astigmatism of \> 1.5 diopters, regular astigmatism.	Large Irregular Astigmatism n=8 Participants Astigmatism of \> 1.5 diopters, irregular astigmatism.
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. elevation difference (2 std. dev.), middle cornea	2.92 micrometer 95% C.I. of Std.Dev. not required by ISO 19980-2012	3.08 micrometer 95% C.I. of Std.Dev. not required by ISO 19980-2012	12.59 micrometer 95% C.I. of Std.Dev. not required by ISO 19980-2012
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. elevation difference (2 std. dev.), centr. cornea	2.00 micrometer 95% C.I. of Std.Dev. not required by ISO 19980-2012	1.84 micrometer 95% C.I. of Std.Dev. not required by ISO 19980-2012	5.72 micrometer 95% C.I. of Std.Dev. not required by ISO 19980-2012

OTHER_PRE_SPECIFIED outcome

Timeframe: 1 day of examination

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).

Outcome measures

Measure	Normal Eye n=34 Participants Astigmatism smaller than 1.5 diopters	Large Regular Astigmatism n=8 Participants Astigmatism of \> 1.5 diopters, regular astigmatism.	Large Irregular Astigmatism n=8 Participants Astigmatism of \> 1.5 diopters, irregular astigmatism.
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. difference of flat meridian (R1)	2.00 micrometer Interval -3.39 to 7.38	-2.59 micrometer Interval -21.98 to 16.8	-28.06 micrometer Interval -61.45 to 5.33
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. difference of steep meridian (R2)	-5.23 micrometer Interval -12.95 to 2.49	-1.63 micrometer Interval -12.57 to 9.32	-59.19 micrometer Interval -131.29 to 12.92

OTHER_PRE_SPECIFIED outcome

Timeframe: 1 day of examination

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.

Outcome measures

Measure	Normal Eye n=34 Participants Astigmatism smaller than 1.5 diopters	Large Regular Astigmatism n=8 Participants Astigmatism of \> 1.5 diopters, regular astigmatism.	Large Irregular Astigmatism n=8 Participants Astigmatism of \> 1.5 diopters, irregular astigmatism.
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.	-0.13 degree Interval -1.85 to 1.59	-0.44 degree Interval -2.02 to 1.14	0.25 degree Interval -3.83 to 4.34

POST_HOC outcome

Timeframe: 1 day of examination

For definition of keratometry axis see outcome measures 4 and 5.

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 normalized difference and 95% confidence interval of mean normalized difference for axis of flat meridian.

Difference is normalized for each eye as function of astigmatism to a refractive error of 0.167 diopters (i.e. an axis difference of 1 normalized degree results in a refractive error of 0.167 diopter), to provide a measure which can be directly related to its impact on visual quality.

Please note that for this analysis a separation in arms "normal eye" and "large regular astigmatism" is not meaningful, thus here both groups are analyzed jointly as group "regular eye"

Outcome measures

Measure	Normal Eye n=42 Participants 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.
Equivalence of Keratometry Axis Measurement Between Lenstar LS 900 Topography and Lenstar LS 900: Population Mean of Normalized Differences of Keratometry Axis Measurement Between Both Devices.	-0.01 normalized degree Interval -0.29 to 0.27	—	—

Adverse Events

Normal Eye

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Large Regular Astigmatism

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Large Irregular Astigmatism

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Dr. Lucio Robledo, Clinical Trials Biometry

Haag Streit AG

Phone: +41 31 978 01 11

Email: lucio.robledo@haag-streit.com

Results disclosure agreements

• Principal investigator is a sponsor employee The sponsor can review results communications prior to public release and can embargo communications regarding trial results for a period that is less than or equal to 60 days from the time submitted to the sponsor for review. The sponsor can require an extension of the embargo for 90 days. If the communication contains confidential information of the sponsor, the sponsor can require to replace this information by scientifically meaningful equivalent information.
• Publication restrictions are in place

Restriction type: OTHER