CataractNCT00347516
Comparative Study of Three IOL Power Calculation Formulae for Asian Eyes Shorter Than 22mm or Longer Than 25mm
A study testing IOL calculation formula in people with Cataract, run by Singapore National Eye Centre at 1 site in Singapore.
Trial summary
Implantation of an intraocular lens is the gold standard in modern day cataract surgery. The appropriate lens power needed to achieve the desired refractive outcome can be calculated with a whole variety of formulas. Read more about this study
- Who is it for?
- Ages 21 years and olderHealthy volunteers can take part
- Conditions the study is for
- Cataract
- What is being tested?
- IOL calculation formula
- Type of treatment
- Surgery or procedure
- How many people
- 210 participants
- Where
- 1 siteSingapore
- Study dates
- Dec 2005to Dec 2009
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 21 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Eyes with significant cataract and suitable for phacoemulsification and primary implantation of posterior chamber intraocular lens.
- Cataract as the only ophthalmic pathology causing significant visual impairment.
- Axial length less than 22mm or more than 25mm, as measured by Zeiss IOL Master.
- Evidence of a personally signed and dated informed consent document indicating the patient (or a legally acceptable representative) has been informed of all pertinent aspects of the trial.
- Patient is willing and able to comply with scheduled visits and other study procedures.
Who cannot join
- Presence of other ophthalmic pathology causing visual impairment: amblyopia, glaucoma, optic neuropathy, age related macular degeneration, macular oedema, retinal detachment, proliferative diabetic retinopathy, ocular inflammation.
- Previous intraocular or corneal surgery (including refractive surgery).
- Corneal opacities or irregularities: previous scarring, dystrophy, ectasia
- Corneal astigmatism greater than 1.5 dioptres.
- Axial length unable to be measured by the Zeiss IOL master.
- Other ocular surgery at time of cataract extraction.
Show all 18Show fewer
- Uncontrolled diabetes.
- Any neurological condition which may interfere with performance of required tests.
- Other severe acute or chronic medical or psychiatric condition that may increase the risk associated with study participation or may interfere with the interpretation of study results.
- Surgical exclusion criteria
- The patient will not be included in the study if any of the following complications are encountered during surgery:
- Inability to achieve secure 'in-the-bag' placement of the IOL (i.e. due to posterior capsule rupture, radial tear in capsulorhexis, vitreous loss, zonular rupture)
- Use of corneal sutures.
- Multiple operative procedures at the time of IOL implantation.
- Post-implantation exclusion criteria:
- Haptic not in the capsular bag.
- Decentration of the IOL of more than 1.0mm.
- Other ocular pathology causing visual impairment that were not apparent prior to surgery (e.g. age related macular degeneration, macular oedema, glaucoma, retinal detachment).
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Comparative Study of Three Intraocular Lens Power Calculation Formulae for Asian Eyes With Axial Lengths Less Than 22mm and Greater Than 25mm
Implantation of an intraocular lens is the gold standard in modern day cataract surgery.
The appropriate lens power needed to achieve the desired refractive outcome can be calculated with a whole variety of formulas.
To date, there has been no prospective study conducted to evaluate the accuracy of the IOL power calculation formulae commonly in use. It is well established that the frequently used IOL formulas do not show significant differences when used in eyes of average axial length (i.e. between 22mm and 25mm) and it is at the extremes of axial lengths where discrepancies arise. Our aim is to find the most appropriate formula(e) for these 'long' and 'short eyes' particularly in our population where there is a significant proportion of high myopes.
Read the detailed description
Our primary objective is to compare three IOL power calculation formulae and determine the most appropriate formula for accurate prediction of postoperative refractive error in Asian eyes with axial length less than 22mm and greater than 25mm that are undergoing phacoemulsification cataract surgery.
This will be a randomized prospective study in patients with axial lengths less than 22mm and greater than 25mm undergoing phacoemulsification cataract surgery and IOL implantation. Each patient will be randomly assigned to have their IOL power calculated using one of three IOL power calculation formulae (SRK-T, Hoffer Q and Holladay 2). A randomization list will be used to decide the IOL formula allocation.
The primary outcome measure of this study is the mean absolute error (MAE) which is calculated by subtracting the intended formula-derived preoperative refractive error from the actual postoperative refractive error.
Based on the estimates from a previous study, it is postulated that the MAE for Hoffer Q, Holladay 2, and SRK-T are +0.36 D, +0.53 D \& +0.74 D, respectively.
The interest here is pair-wise comparisons amongst SRK-T, Hoffer Q and Holladay 2. The sample size calculations for each pair-wise comparison is based on a SD of 0.57 D with a power of 80% and a 2-sided test of 5%. Using equal randomization, a total of 176 subjects would be sufficient to achieve statistical differences between Hoffer Q over the Holladay 2 \& SRK-T and also the Holladay 2 over SRK-T (standardized effect difference of 30% between Hoffer Q \& Holladay 2; 67% \& 37% effect size for Hoffer Q vs SRK-T and Hollady 2 vs SRK-T, respectively).
Factoring in an attrition rate of 20%, a total sample size of 210 eyes will be recruited for the study.
Preoperatively, Snellen visual acuity will be assessed and all patients will undergo a non-cycloplegic autorefraction, keratometry measurement and axial length measurement with the Zeiss IOL Master (see below Visit 1). All patients will undergo phacoemulsification and 'in-the-bag' IOL implantation (Visit 2). Surgery will be performed through a 2.75mm temporal clear corneal incision and only the Alcon MA60BM or MA60MA 3-piece acrylic foldable IOL will be implanted. A standard postoperative topical antibiotic and anti-inflammatory regime consisting of tobramycin and beclomethasone will be administered (Visit 3-5).
Patients will be examined at the following intervals:
Screening Within 90 days prior to surgery Preoperative (Visit 1) Within 30 days prior to surgery Operative (Visit 2) Day of surgery Postoperative (Visit 3) 1 day after surgery Postoperative (Visit 4) 3-5 days after surgery Postoperative (Visit 5) 4-5 weeks after surgery Postoperative (Visit 6) 3-4 months after surgery
Postoperatively, logMAR visual acuity will be recorded at every visit and non-cycloplegic refraction will be carried out at Visit 5 and Visit 6.
- Conditions
- Cataract
- Being tested
- IOL calculation formula
- Keywords
- IOL formula, High myopia, axial length
- Medical subject headings
- Cataract
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
IOL calculation formulaProcedure or surgery
What is being measured
The primary outcome is the main question the study is designed to answer.
Mean absolute error (MAE) which is calculated by subtracting the intended formula-derived preoperative refractive error from the actual postoperative refractive error.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted4 Jul 2006 (estimated)
- Study startDec 2005
- Primary completionDec 2009
- Study completionDec 2009
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for CataractStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Enrolment
- 210 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Singapore National Eye Centre
- Sponsor type
- Other government
- Collaborators
- Singapore Eye Research Institute
- Investigators
- Zainah Alsagoff, FRCSEd, Principal investigator, Singapore National Eye Centre
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT00347516
- Sponsor's protocol ID
- R430/25/2005
- Status last verified
- May 2010
- First submitted
- 30 Jun 2006
- Last updated
- 12 May 2010
- Results posted
- No
Study at a glance
From the registry record, last updated by the sponsor on 12 May 2010. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Comparative Study of Three Intraocular Lens Power Calculation Formulae for Asian Eyes With Axial Lengths Less Than 22mm and Greater Than 25mm
- ClinicalTrials.gov ID
- NCT00347516
- Acronym / sponsor ID
- R430/25/2005
- Conditions
- Cataract
- Keywords
- IOL formula, High myopia, axial length
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 210 participants (estimated)
- Lead sponsor
- Singapore National Eye CentreOther government
- Collaborators
- Singapore Eye Research Institute
- Study start
- Dec 2005
- Primary completion
- Dec 2009 (actual)
- Study completion
- Dec 2009 (actual)
- First posted
- 4 Jul 2006 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Implantation of an intraocular lens is the gold standard in modern day cataract surgery.
The appropriate lens power needed to achieve the desired refractive outcome can be calculated with a whole variety of formulas.
To date, there has been no prospective study conducted to evaluate the accuracy of the IOL power calculation formulae commonly in use. It is well established that the frequently used IOL formulas do not show significant differences when used in eyes of average axial length (i.e. between 22mm and 25mm) and it is at the extremes of axial lengths where discrepancies arise. Our aim is to find the most appropriate formula(e) for these 'long' and 'short eyes' particularly in our population where there is a significant proportion of high myopes.
Detailed description
Our primary objective is to compare three IOL power calculation formulae and determine the most appropriate formula for accurate prediction of postoperative refractive error in Asian eyes with axial length less than 22mm and greater than 25mm that are undergoing phacoemulsification cataract surgery.
This will be a randomized prospective study in patients with axial lengths less than 22mm and greater than 25mm undergoing phacoemulsification cataract surgery and IOL implantation. Each patient will be randomly assigned to have their IOL power calculated using one of three IOL power calculation formulae (SRK-T, Hoffer Q and Holladay 2). A randomization list will be used to decide the IOL formula allocation.
The primary outcome measure of this study is the mean absolute error (MAE) which is calculated by subtracting the intended formula-derived preoperative refractive error from the actual postoperative refractive error.
Based on the estimates from a previous study, it is postulated that the MAE for Hoffer Q, Holladay 2, and SRK-T are +0.36 D, +0.53 D \& +0.74 D, respectively.
The interest here is pair-wise comparisons amongst SRK-T, Hoffer Q and Holladay 2. The sample size calculations for each pair-wise comparison is based on a SD of 0.57 D with a power of 80% and a 2-sided test of 5%. Using equal randomization, a total of 176 subjects would be sufficient to achieve statistical differences between Hoffer Q over the Holladay 2 \& SRK-T and also the Holladay 2 over SRK-T (standardized effect difference of 30% between Hoffer Q \& Holladay 2; 67% \& 37% effect size for Hoffer Q vs SRK-T and Hollady 2 vs SRK-T, respectively).
Factoring in an attrition rate of 20%, a total sample size of 210 eyes will be recruited for the study.
Preoperatively, Snellen visual acuity will be assessed and all patients will undergo a non-cycloplegic autorefraction, keratometry measurement and axial length measurement with the Zeiss IOL Master (see below Visit 1). All patients will undergo phacoemulsification and 'in-the-bag' IOL implantation (Visit 2). Surgery will be performed through a 2.75mm temporal clear corneal incision and only the Alcon MA60BM or MA60MA 3-piece acrylic foldable IOL will be implanted. A standard postoperative topical antibiotic and anti-inflammatory regime consisting of tobramycin and beclomethasone will be administered (Visit 3-5).
Patients will be examined at the following intervals:
Screening Within 90 days prior to surgery Preoperative (Visit 1) Within 30 days prior to surgery Operative (Visit 2) Day of surgery Postoperative (Visit 3) 1 day after surgery Postoperative (Visit 4) 3-5 days after surgery Postoperative (Visit 5) 4-5 weeks after surgery Postoperative (Visit 6) 3-4 months after surgery
Postoperatively, logMAR visual acuity will be recorded at every visit and non-cycloplegic refraction will be carried out at Visit 5 and Visit 6.
Study design
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
Who may qualify
- Ages
- 21 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Eyes with significant cataract and suitable for phacoemulsification and primary implantation of posterior chamber intraocular lens.
- Cataract as the only ophthalmic pathology causing significant visual impairment.
- Axial length less than 22mm or more than 25mm, as measured by Zeiss IOL Master.
- Evidence of a personally signed and dated informed consent document indicating the patient (or a legally acceptable representative) has been informed of all pertinent aspects of the trial.
- Patient is willing and able to comply with scheduled visits and other study procedures.
Key exclusion criteria (18 listed)
- Presence of other ophthalmic pathology causing visual impairment: amblyopia, glaucoma, optic neuropathy, age related macular degeneration, macular oedema, retinal detachment, proliferative diabetic retinopathy, ocular inflammation.
- Previous intraocular or corneal surgery (including refractive surgery).
- Corneal opacities or irregularities: previous scarring, dystrophy, ectasia
- Corneal astigmatism greater than 1.5 dioptres.
- Axial length unable to be measured by the Zeiss IOL master.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| IOL calculation formula | Procedure or surgery | – |
Primary outcome
Mean absolute error (MAE) which is calculated by subtracting the intended formula-derived preoperative refractive error from the actual postoperative refractive error.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 12 May 2010.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Zainah Alsagoff, FRCSEd principal investigator
Singapore National Eye Centre
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing IOL calculation formula in people with Cataract, run by Singapore National Eye Centre at 1 site in Singapore.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 18 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 12 May 2010. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Singapore. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Mean absolute error (MAE) which is calculated by subtracting the intended formula-derived preoperative refractive error from the actual postoperative refractive error.. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 12 May 2010.