ANZCTR - Registration

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Trial registered on ANZCTR

Registration number

ACTRN12616001593426

Ethics application status

Approved

Date submitted

2/11/2016

Date registered

18/11/2016

Date last updated

6/04/2018

Type of registration

Prospectively registered

Titles & IDs

Public title

The determinants of corneal curvature in healthy participants and in cataract surgery patients

Scientific title

Analysis of corneal refractive power changes associated with accommodation, corneal biomechanics and cataract surgery

Secondary ID [1]

Nil known

Universal Trial Number (UTN)

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Cornea after Cataract surgery

Condition category

Condition code

Eye

Diseases / disorders of the eye

Intervention/exposure

Study type

Observational

Patient registry

False

Target follow-up duration

Target follow-up type

Description of intervention(s) / exposure

All the investigations involved in this study are non-invasive and non-contact procedures that are routinely used in clinical ophthalmology.

The first part of the study comparative diagnostic trial to compare clinical aberrometers. Participants will be examined on 4 different types of aberrometers (as described below) at a single half an hour long visit This part will commence in the first instance, approximately a month before the first cataract patient is assessed.

The second is non randomized observational trial to examine changes in corneal curvature associated with ocular accommodation assessed with corneal tomography and aberrometry and the relative influence of corneal biomechanics. Healthy participants will undergo corneal tomography and aberrometry, (Galilei 2 and Orbscan) and corneal biomehanics (Corvis-ST), as described below. The assessments will only take up to half an hour at a single visit. The second part will run concurrently with the third part of the study.

The final and arguably the most important part, is observational cohort study to characterise the relationship between corneal incision architecture and corneal biomechanics on two different incision sizes of surgically induced astigmatism following cataract surgery, using clinical aberrometry, corneal accommodation using tomography and corneal biomechanics. In this part, all the patients will be assessed at least a few hours once before the surgery, and 3 times after the surgery, which is standard of care for patients after cataract surgery. Assessments only take about 30 additional minutes more than their regular follow-up visit.

Visual acuity: Vision will be assessed using a letter chart. This is done as a standard of care for all the patients undergoing cataract surgery.

Slit-lamp biomicroscopy: Standard eye examination will be performed using a special microscope called a slit-lamp, which is used in every eye clinic room.

Aberrometry and tomography: The curvature of the front part of eye will be measured using special instruments known as the Orbscan II, Zywave, OPDIII, iDesign and Galilei 2 (only Galilei 2 for the third part). The instruments are used to assess the shape, refractive properties and thickness of cornea.

Biomechanical properties of cornea: The biomechanics (rigidity and flexibility) of the front part of your eye will be measured with a special instrument called Corvis-ST. This instrument also uses a gentle air puff for measurement. It does not cause any discomfort or pain to the eyes.

Optical Coherence Tomography: The instrument produces high resolution images the front of the eye with a special laser camera called anterior segment - Optical Coherence Tomographer (AS-OCT).

Specular microscopy: This technique is used to evaluate the health of corneal endothelium. The endothelial cell density will be quantified after obtaining clinical images.

Intervention code [1]

Diagnosis / Prognosis

Comparator / control treatment

No control group

Control group

Uncontrolled

Outcomes

Primary outcome [1]

Relationship between biomechanics of the cornea, using Corvis-ST, and surgically induced astigmatism, using tomographer (Galilei 2), following cataract surgery.

Timepoint [1]

Patients will be assessed at least a few hours before surgery, and, one day, one month and three months after the surgery.

Primary outcome [2]

Relationship between biomechanics of the cornea and wound architecture following cataract surgery. Biomechanics of the cornea will be measured by Corvis-ST and wound architecture by anterior segment optical coherence tomographer (AS-OCT) and Specular microscopy.

Timepoint [2]

Patients will be assessed at least a few hours before surgery, and, one day, one month and three months after surgery.

Secondary outcome [1]

Topographical maps and corneal higher order aberrations obtained by 4 different aberrometers (Zywave, OPDIII, iTrace and Galilei 2) will be compared. This is a composite secondary outcome.

Timepoint [1]

This is the first part of the study. Three months from the commencement of the project.

Eligibility

Key inclusion criteria

Part 1 and 2: Ametropia <1D (defocus or astigmatism). Participants can be healthy volunteers.
Part 3: Patients scheduled for routine cataract surgery.

Minimum age

18 Years

Maximum age

No limit

Sex

Both males and females

Can healthy volunteers participate?

Yes

Key exclusion criteria

Part 1: Ametropia >1D (defocus or astigmatism)
Part 1, 2 and 3: Pre-existing ocular pathology or previous ocular surgery, Contact lens use,
Strabismus, Previous ocular trauma

Study design

Purpose

Duration

Longitudinal

Selection

Timing

Prospective

Statistical methods / analysis

All statistical analysis will be completed using the R statistical software package and Microsoft Excel.
Part 1: The difference in total and individual HOA will be investigated using basic plots to visualise the raw data, investigate outliers and the spread of the data. Analysis of variance (ANOVA) and multivariate analysis of variance (MANOVA) and canonical discriminat analysis will be used to compare HOA with post hoc tests where required. Non-normal data will be analysed using non-parametric tests.
Part 2: Statistical analysis will include analysis as described for Part 1 in addition to correlation and regression analysis to investigate the relationship between Corvis-ST data and accommodation induced corneal tomographic changes.
Part 3: Surgically induced astigmatism (SAI) will be calculated for all patients based on pre and post-operative tomography data using vector analysis. The relationship between SIA magnitude, corneal biomechanics, and corneal wound architecture will be modelled using regression analysis.

Recruitment

Recruitment status

Active, not recruiting

Date of first participant enrolment

Anticipated

21/11/2016

Actual

28/11/2016

Date of last participant enrolment

Anticipated

1/11/2017

Actual

1/12/2017

Date of last data collection

Anticipated

28/09/2018

Actual

Sample size

Target

180

Accrual to date

Final

140

Recruitment outside Australia

Country [1]

New Zealand

State/province [1]

Auckland

Funding & Sponsors

Funding source category [1]

University

Name [1]

The University of Auckland

Address [1]

Department of Ophthalmology
New Zealand National Eye Centre
Faculty of Medical and Health Sciences
The University of Auckland,
Private Bag 92019
Auckland 1142

Country [1]

New Zealand

Primary sponsor type

University

Name

The University of Auckland

Address

Department of Ophthalmology
New Zealand National Eye Centre
Faculty of Medical and Health Sciences
The University of Auckland,
Private Bag 92019
Auckland 1142

Country

New Zealand

Secondary sponsor category [1]

None

Name [1]

None

Address [1]

None

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Health and Disability Ethics Committee

Ethics committee address [1]

Health and Disability Ethics Committees
Ministry of Health
Freyberg Building
20 Aitken Street
PO Box 5013
Wellington
6011

Ethics committee country [1]

New Zealand

Date submitted for ethics approval [1]

02/09/2016

Approval date [1]

22/09/2016

Ethics approval number [1]

HDEC 16/CEN/132

Summary

Brief summary

Following removal of a cataract, an intraocular lens (IOL) is implanted during surgery to enable refractive correction of the eye to maximise vision following surgery. Selecting the correct model and refractive power of the IOL is critical to achieve the appropriate refractive target.  A sub-optimally selected IOL will typically result in post-operative residual refractive error, and decreased unaided vision that may be associated with falls and decreased quality of life in many cases. 

Refractive error is caused by the combined effect of the cornea and the lens and can be divided into lower order aberrations (LOA) and higher order aberrations (HOA).
To select an appropriate model IOL to minimise total spherical aberration and accurate assessment of corneal aberration is required prior to surgery. The first part of this study will compare four clinical aberrometers that use different optical principals to assess HOA in the eye.

Ocular accommodation is the process by which the crystalline lens adjusts the focus of the eye through conformational changes. A new strategy to accurately assess corneal curvature changes will be developed using 3D printed modifications to existing clinical tomographers and aberromters to allow corneal curvature assessment at near and distance fixation. Using this strategy even small changes in the corneal periphery should be quantifiable to definitively establish of the role of the cornea in accommodation. This is the second part  of the project.

Cataract surgery typically involves small incisions placed in the peripheral cornea to extract the cataract using phacoemulsification, and to enable implantation of an intraocular lens following cataract removal.  The size of the corneal incisions depends on the IOL that is selected and the lens cartridge that is required for insertion. 

The final part of this study will aim to characterise the relative contribution of wound architecture and corneal biomechanics on surgically induced astigmatism.

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

Dr James McKelvie

Address

Department of Ophthalmology
New Zealand National Eye Centre
Faculty of Medical and Health Sciences
The University of Auckland,
Private Bag 92019
Auckland 1142

Country

New Zealand

Phone

+64 9 923 6712

Fax

[email protected]

Contact person for public queries

Name

James McKelvie

Address

Department of Ophthalmology
New Zealand National Eye Centre
Faculty of Medical and Health Sciences
The University of Auckland,
Private Bag 92019
Auckland 1142

Country

New Zealand

Phone

+64 9 923 6712

Fax

[email protected]

Contact person for scientific queries

Name

James McKelvie

Address

Department of Ophthalmology
New Zealand National Eye Centre
Faculty of Medical and Health Sciences
The University of Auckland,
Private Bag 92019
Auckland 1142

Country

New Zealand

Phone

+64 9 923 6712

Fax

[email protected]

No information has been provided regarding IPD availability

What supporting documents are/will be available?

Current supporting documents:

Updated to:

Doc. No.	Type	Citation	Link	Other Details
23458	Other	Wallace, H. B., Misra, S. L., Li, S. S., & McKelvie, J. (2019). Biomechanical changes in the cornea following cataract surgery: A prospective assessment with the Corneal Visualisation Scheimpflug Technology. Clinical & experimental ophthalmology, 47(4), 461-468.	https://onlinelibrary.wiley.com/doi/full/10.1111/ceo.13451
23459	Other	Wallace, H. B., Misra, S. L., Li, S. S., & McKelvie, J. (2018). Predicting pseudophakic refractive error: Interplay of biometry prediction error, anterior chamber depth, and changes in corneal curvature. Journal of Cataract & Refractive Surgery, 44(9), 1123-1129.	https://www.sciencedirect.com/science/article/pii/S0886335018304905
23460	Other	Li, S. S., Misra, S. L., Wallace, H. B., & McKelvie, J. (2018). Effect of phacoemulsification incision size on incision repair and remodeling: Optical coherence tomography assessment. Journal of Cataract & Refractive Surgery, 44(11), 1336-1343.	https://www.sciencedirect.com/science/article/pii/S0886335018306321
23806	Other			The details of published peer-reviewed scientific ... [More Details]

Results publications and other study-related documents

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

Source	Title	Year of Publication	DOI
Embase	Effect of phacoemulsification incision size on incision repair and remodeling: Optical coherence tomography assessment.	2018	https://dx.doi.org/10.1016/j.jcrs.2018.07.025

N.B. These documents automatically identified may not have been verified by the study sponsor.

Trial Review

Documents added manually

Documents added automatically