Lens replacement planning in patients with cataracts and corneal astigmatism using the iTrace program

Plain English Summary

Background and study aims
An estimated 40 to 50% of the population aged over 60 years has significant astigmatism (change in the curve of the eye resulting in blurred and distorted vision). The same proportion of patients with cataracts (clouding of the lens in the eye which leads to a decrease in vision) also have astigmatism. Cataracts are treated through lens replacement surgery of the cloudy lens with a clear artificial lens. Managing astigmatism faced by a large number of patients has become crucial in modern cataract surgery. If there is significant astigmatism after surgery this will have an effect on vision quality and spectacle independence, which can leave patients dissatisfied. Toric intraocular lenses, which are the type of artificial lenses used in this study, have become an increasingly common replacement due to their advantage of predictably, stably, and safely correcting preexisting astigmatism. Currently, there is no standard technique for measuring astigmatism.

The factors influencing whether an astigmatism is successfully corrected following surgery include accurate pre-surgical measurements, the size and direction of surgical incision, correct calculation of the dimensions of the toric lens needed, the stability of the lens, and lens tilt. The aim of this study is to investigate the outcomes of planning lens replacement surgery with iTrace toric calculator and whether this has better outcomes than the current standard calculation and planning tools.

This study will evaluate the visual outcomes for cataracts and astigmatism, lens stability after surgical planning using iTrace, and the safety and effectiveness of iTrace as a planning device.

Who can participate?
Participants who have cataracts and have regular corneal astigmatism, with no other current or previous eye disease, who require lens replacement and would like the implantation of a toric lens which can correct the visual issues experienced due to astigmatism, will be recruited to the trial.

What does the study involve?
All recruited participants will receive a full eye examination and testing and an eye scan with the iTrace system. This information will be used to calculate and plan their lens replacement surgery with the aim to restore perfect vision. They will receive their lens implantation, which follows the same procedure as the current standard. Over the following 3 months, participants will be assessed for the success of the lens implantation through various eye examinations and tests the same as those undertaken before surgery.

What are the possible benefits and risks of participating?
Through the planning and evaluation of the surgical process in the study, it is anticipated that participants will receive even more satisfactory visual improvements than if they were to receive the standard surgical procedure.

The surgical operation follows the standard surgical procedure, the only change is that more accurate measurement equipment is used in the surgical planning, therefore there is no increase in the risk of the surgery. The study aims to improve the effect on vision of the surgery

Where is the study run from?
Shanxi Eye Hospital (China)

When is the study starting and how long is it expected to run for?
May 2017 to July 2019

Who is funding the study?
Shanxi Science and Technology Department (China0

Who is the main contact?
Dr Zhe Zhang

Study website

Type

Scientific

Contact name

Dr Zhe Zhang

ORCID ID

http://orcid.org/0000-0002-7209-614X

Contact details

Shanxi Eye Hospital
No. 100 Fudong Street
Liu Xiang Shang Quan
Xinghualing
Taiyuan
030001
China
+8613994209797
whypotato@126.com

EudraCT/CTIS number

Nil known

IRAS number

ClinicalTrials.gov number

Nil known

Protocol/serial number

201601D021142

Scientific title

Clinical evaluation of the safety and effectiveness of toric intraocular lens implantation planning based on iTrace wavefront keratometric astigmatism calculation

Acronym

Study hypothesis

Using iTrace built-in toric calculator with wavefront keratometric astigmatism values for toric IOL planning is safe and effective

Ethics approval(s)

Approved 15/01/2017, Medical Ethics Committee of Shanxi Eye Hospital (100 Fudong St, Liu Xiang Shang Quan, Xinghualing, Taiyuan, Shanxi, 030001 China; +863518286882; eye8286500@163.com), ref: N20170309

Study design

Prospective interventional single-center study

Primary study design

Interventional

Secondary study design

Non randomised study

Study setting(s)

Hospital

Study type

Treatment

Patient information sheet

No participant information sheet available

Condition

Cataracts with corneal astigmatism

Intervention

All patients with cataract and preexisting corneal astigmatism underwent phacoemulsification and toric IOL implantation. The IOL power and cylinders were chosen with the help of the iTrace toric planning program using wavefront keratometric astigmatism.

All patients had a full ophthalmologic examination at baseline including subjective refraction, uncorrected distance and best-corrected visual acuity measurements, a slit-lamp examination, Goldmann applanation tonometry, and fundoscopy in mydriasis. Ocular biometry was performed using a partial coherence interferometry device (IOL Master 500, Carl Zeiss Meditec AG). Corneal topography was measured using the Oculus Pentacam (Optikgeräte GmbH, Wetzlar, Germany) and iTrace Surgical Workstation. All measurements were acquired in automatic release mode for each eye before using any eye drops or performing other contact-based examinations. Eye alignment evaluations and measurements with good quality (graded as “ok”) obtained via Pentacam, were used in the final analysis. The participant was placed in front of the iTrace and his or her head was carefully aligned with the chin and forehead fixed with the help of an assistant.

All measurements were performed in a semidark room with undilated pupils.

Postoperative examinations were performed at 1 week, 1 month, 3 months, 6 months and 1 year following surgery and included uncorrected and corrected distance visual acuity, intraocular pressure, subjective and objective (autorefractometry) refractions, slit-lamp evaluation, and corneal topography (Pentacam HR and iTrace).

The IOL axis was assessed with toriCAM (Graham Barrett, AppStore, USA) at the slit-lamp following mydriasis. The toriCAM is a newly developed smartphone application, invented by Professor Graham Barrett, based on the accelerometer and gyroscope built into modern smartphones that can provide a photographic analysis to identify the actual IOL axis postoperatively.

Intervention type

Procedure/Surgery

Primary outcome measure

1. Astigmatic changes assessed by vector analysis using the Alpins method at baseline and 3 months
2. Postoperative refractive error assessed by the display of the postoperative refractive cylinder at 3 months

Secondary outcome measures

1. Visual acuity assessed using a Snellen E chart at baseline and 3 months
2. IOL axial position is measured with toriCAM when participants underwent mydriasis at 3 months
3. Corneal astigmatism measured with different devices are compared

Overall study start date

02/05/2017

Overall study end date

22/07/2019

Reason abandoned (if study stopped)

Participant inclusion criteria

1. Cataracts with preexisting regular corneal astigmatism and requested toric IOL implantation
2. Cylindric values between 0.75 D and 5.0 D.

Participant type(s)

Patient

Age group

Adult

Sex

Both

Target number of participants

60

Total final enrolment

63

Participant exclusion criteria

1. Pregnancy and/or lactation
2. Irregular corneal astigmatism
3. Diabetic retinopathy
4. Iris neovascularization
5. Congenital eye abnormalities
6. Severe unstable tear film
7. Retinal detachment
8. Glaucoma
9. Pseudoexfoliation syndrome
10. Uveitis
11. Long-term anti-inflammatory treatment
12. Amblyopia
13. Advanced age-related macular degeneration
14. Previous ocular surgery
15. Severe corneal and/or retinal disease
16. History of eye trauma

Recruitment start date

02/01/2018

Recruitment end date

01/06/2019

Countries of recruitment

China

Study participating centre

Shanxi Eye Hospital
No. 100 Fudong Street
Liu Xiang Shang Quan
Xinghualing
Taiyuan
030001
China

Organisation

Shanxi Eye Hospital

Sponsor details

No.100 Fudong Street
Liu Xiang Shang Quan
Xinghualing
Taiyuan
030001
China
+86 3518286882
sxent@sxent.org

Sponsor type

Hospital/treatment centre

Website

https://www.sxsyk.com/web/index

Funder type

Government

Funder name

ShanXi Science and Technology Department

Alternative name(s)

山西省科学技术厅, Shanxi Provincial Department of Science and Technology, Department of Science and Technology of Shanxi Province, Science and Technology Department of ShanXi Province, Shanxi Science and Technology Department

Funding Body Type

government organisation

Funding Body Subtype

Local government

Location

China

Publication and dissemination plan

Planned publication in a high-impact peer-reviewed journal

2020 results preprint in https://doi.org/10.21203/rs.2.24137/v2 (added 10/08/2020)

Intention to publish date

31/07/2020

Individual participant data (IPD) sharing plan

The data-sharing plans for the current study are unknown and will be made available at a later date

IPD sharing plan summary

Data sharing statement to be made available at a later date

Study outputs