Narrow Angle Patients at Risk for Angle Closure GlaucomaNCT01758237
Dysphotopsia Following Laser Peripheral Iridotomy
A study testing Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser and Nd:YAG Laser Peripheral Iridotomy in people with Narrow Angle Patients at Risk for Angle Closure Glaucoma, run by Credit Valley EyeCare at 1 site in Canada.
Trial summary
To establish the correlation of the location of the Nd:YAG laser peripheral iridotomy to the post operative visual symptoms experienced by some patients. The investigators hypothesize that fully uncovered laser peripheral iridotomy will produce less significant dysphotopsia, due to avoidance of the prismatic effect… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Narrow Angle Patients at Risk for Angle Closure Glaucoma
- What is being tested?
- Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser and Nd:YAG Laser Peripheral Iridotomy
- Type of treatment
- Medical device, Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 214 participants
- Where
- 1 siteCanada
- Study dates
- Jan 2008to Jan 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 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Able and willing to make the required study visit
- Able and willing to give consent and follow study instructions
- An indication to undergo laser peripheral iridotomy (narrow angles, occludeable angle at risk of acute angle closure, pupil block condition, chronic angle closure, pigment dispersion syndrome)
Who cannot join
- Previous intraocular surgery
- Best corrected visual acuity worse than 20/40
- Asymmetrical ptosis of more than 2mm
- Any active intraocular inflammation
- Acute attack of angle closure glaucoma
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Incidence of Visual Symptom Following Laser (Nd:YAG ) Peripheral Iridotomy (LPI) in Relation to Position of LPI
To establish the correlation of the location of the Nd:YAG laser peripheral iridotomy to the post operative visual symptoms experienced by some patients. The investigators hypothesize that fully uncovered laser peripheral iridotomy will produce less significant dysphotopsia, due to avoidance of the prismatic effect produced by the tear film than those covered.
Read the detailed description
Nd:YAG LPI is a frequently performed procedure for patients who have narrow angles at risk of acute angle closure glaucoma, pupillary-block conditions, chronic angle closure, and pigment dispersion syndrome. Most complications associated with the procedure are benign and include intraocular pressure (IOP) spike, transient uveitis, hyphema, corneal or lens damage and closure of the iridotomy. Visual disturbances have been also reported but only a few papers address this specific issue. The rate of these symptoms vary between 2.7% and 4%. It is believed that these symptoms are associated with the fact that light enters through the LPI and thus creating abnormal visual symptoms. Hence it has been suggested to carefully place the LPI so that the eyelid fully covers the LPI, therefore preventing light getting through. However, reports of patients with fully covered LPIs and visual disturbances have led to hypothesize the theory that even when fully covered by the eyelid, light can access through the LPI by a base-up prism created by the tear meniscus at the lid margin. Therefore, placement of the LPI, fully covered, partially covered or totally uncovered can potentially lead to equally significant symptoms. This study will attempt to address the issue of placement of the LPI in relationship with visual symptoms.
- Being tested
- Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser, Nd:YAG Laser Peripheral Iridotomy
- Keywords
- Laser Peripheral Iridotomy, Visual Dysphotopsia, Visual Disturbances, Angle Closure Glaucoma
- Medical subject headings
- Glaucoma, Angle-Closure
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laserDevice
Also called Nd:YAG Laser
This device is used to perform the peripheral iridotomy on all patients. It is a standard of care approved device.
Nd:YAG Laser Peripheral IridotomyProcedure or surgery
Also called Nd:YAG LPI
After application of topical anesthetic to the eye undergoing the LPI, the patient is seated at the laser machine. Abraham iridotomy lens filled with a viscous material will be used to facilitate the procedure. The thinnest area of the iris quadrant treated will be chosen. Nd:YAG Laser will be applied until iridotomy is opened satisfactory.
| Study group | Role | What they receive |
|---|---|---|
| Superior Laser Peripheral Iridotomy | Experimental | Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser peripheral iridotomy was performed on the superior aspect of the iris in the eye being treated. This will be in the 11 to 1 o'clock position. Receives: Device: Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser; Procedure: Nd:YAG Laser Peripheral Iridotomy |
| Temporal Laser Peripheral Iridotomy | Experimental | Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser peripheral iridotomy was performed on the temporal aspect of the iris in the eye being treated. The position will be in the 2 to 4 o'clock in the left eye and 8 to 10 o'clock in the right eye. Receives: Device: Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser; Procedure: Nd:YAG Laser Peripheral Iridotomy |
What is being measured
The primary outcome is the main question the study is designed to answer.
Presence of Linear Dysphotopsia
The change in presence of linear dysphotopsia from baseline (prior to intervention) to 1 month after the Nd:YAG laser intervention is performed.
Measured: Baseline (Time =0),1 month
Secondary outcomes (3)
Presence of Visual Dysphotopsia
This includes Halo, Crescent, Ghost Images, Glare, Shadows. This records the change in the presence of these symptoms from baseline (prior to intervention) and 1 month after the Nd:YAG laser intervention.
Measured: Baseline (Time = 0), 1 month
Pain Experienced
The pain experienced when the Nd:YAG procedure is performed. This is on a scale of 0-10 with 0 being no pain and 10 the most severe pain imaginable.
Measured: Procedure (Time = 0)
Nd:YAG Laser Power Used
The amount of laser power used on the Nd:YAG laser to perform the intervention.
Measured: Procedure (Time = 0)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted1 Jan 2013 (estimated)
- Study startJan 2008
- Primary completionJan 2009
- Study completionJan 2009
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (7)Papers the sponsor has linked to this study.
- Other trials for Narrow Angle Patients at Risk for Angle Closure GlaucomaStudies 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
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 214 participants (actual)
Sponsor and investigators
- Lead sponsor
- Credit Valley EyeCare
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Principal investigator, Iqbal Ike Ahmed, Credit Valley EyeCare
- Investigators
- Iqbal Ike K Ahmed, MD, Principal investigator, University of Toronto, Toronto, Canada. University of Utah, Salt Lake City, USAVanessa Vera, MD, Study director, University of Toronto, Canada
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT01758237
- Sponsor's protocol ID
- CVEC-LPI
- Status last verified
- Feb 2013
- First submitted
- 20 Dec 2012
- Last updated
- 13 Feb 2013
- Results posted
- No
- Data monitoring committee
- No
Publications
Khodadoust AA, Arkfeld DF, Caprioli J, Sears ML. Ocular effect of neodymium-YAG laser. Am J Ophthalmol. 1984 Aug 15;98(2):144-52. doi: 10.1016/0002-9394(87)90348-5.
PubMed 6548087Murphy PH, Trope GE. Monocular blurring. A complication of YAG laser iridotomy. Ophthalmology. 1991 Oct;98(10):1539-42. doi: 10.1016/s0161-6420(91)32091-8.
PubMed 1961641Spaeth GL, Idowu O, Seligsohn A, Henderer J, Fonatanarosa J, Modi A, Nallamshetty HS, Chieh J, Haim L, Steinmann WC, Moster M. The effects of iridotomy size and position on symptoms following laser peripheral iridotomy. J Glaucoma. 2005 Oct;14(5):364-7. doi: 10.1097/01.ijg.0000177213.31620.02.
PubMed 16148584Weintraub J, Berke SJ. Blurring after iridotomy. Ophthalmology. 1992 Apr;99(4):479-80. doi: 10.1016/s0161-6420(92)38516-1. No abstract available.
PubMed 1584561Congdon N, Yan X, Friedman DS, Foster PJ, van den Berg TJ, Peng M, Gangwani R, He M. Visual symptoms and retinal straylight after laser peripheral iridotomy: the Zhongshan Angle-Closure Prevention Trial. Ophthalmology. 2012 Jul;119(7):1375-82. doi: 10.1016/j.ophtha.2012.01.015. Epub 2012 Mar 14.
PubMed 22424576Chung RS, Guan AE. Unusual visual disturbance following laser peripheral iridotomy for intermittent angle closure glaucoma. Graefes Arch Clin Exp Ophthalmol. 2006 Apr;244(4):532-3. doi: 10.1007/s00417-005-0129-x. Epub 2005 Oct 14. No abstract available.
PubMed 16228219Vera V, Naqi A, Belovay GW, Varma DK, Ahmed II. Dysphotopsia after temporal versus superior laser peripheral iridotomy: a prospective randomized paired eye trial. Am J Ophthalmol. 2014 May;157(5):929-35. doi: 10.1016/j.ajo.2014.02.010. Epub 2014 Feb 14.
PubMed 24531024
Study at a glance
From the registry record, last updated by the sponsor on 13 Feb 2013. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Incidence of Visual Symptom Following Laser (Nd:YAG ) Peripheral Iridotomy (LPI) in Relation to Position of LPI
- ClinicalTrials.gov ID
- NCT01758237
- Acronym / sponsor ID
- CVEC-LPI
- Keywords
- Laser Peripheral Iridotomy, Visual Dysphotopsia, Visual Disturbances, Angle Closure Glaucoma
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 214 participants (actual)
- Lead sponsor
- Credit Valley EyeCareIndustry (pharma, biotech, devices)
- Study start
- Jan 2008
- Primary completion
- Jan 2009 (actual)
- Study completion
- Jan 2009 (actual)
- First posted
- 1 Jan 2013 (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.
To establish the correlation of the location of the Nd:YAG laser peripheral iridotomy to the post operative visual symptoms experienced by some patients. The investigators hypothesize that fully uncovered laser peripheral iridotomy will produce less significant dysphotopsia, due to avoidance of the prismatic effect produced by the tear film than those covered.
Detailed description
Nd:YAG LPI is a frequently performed procedure for patients who have narrow angles at risk of acute angle closure glaucoma, pupillary-block conditions, chronic angle closure, and pigment dispersion syndrome. Most complications associated with the procedure are benign and include intraocular pressure (IOP) spike, transient uveitis, hyphema, corneal or lens damage and closure of the iridotomy. Visual disturbances have been also reported but only a few papers address this specific issue. The rate of these symptoms vary between 2.7% and 4%. It is believed that these symptoms are associated with the fact that light enters through the LPI and thus creating abnormal visual symptoms. Hence it has been suggested to carefully place the LPI so that the eyelid fully covers the LPI, therefore preventing light getting through. However, reports of patients with fully covered LPIs and visual disturbances have led to hypothesize the theory that even when fully covered by the eyelid, light can access through the LPI by a base-up prism created by the tear meniscus at the lid margin. Therefore, placement of the LPI, fully covered, partially covered or totally uncovered can potentially lead to equally significant symptoms. This study will attempt to address the issue of placement of the LPI in relationship with visual symptoms.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Superior Laser Peripheral Iridotomy | Experimental | Device: Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser, Procedure: Nd:YAG Laser Peripheral IridotomyNeodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser peripheral iridotomy was performed on the superior aspect of the iris in the eye being treated. This will be in the 11 to 1 o'clock position. |
| Temporal Laser Peripheral Iridotomy | Experimental | Device: Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser, Procedure: Nd:YAG Laser Peripheral IridotomyNeodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser peripheral iridotomy was performed on the temporal aspect of the iris in the eye being treated. The position will be in the 2 to 4 o'clock in the left eye and 8 to 10 o'clock in the right eye. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- Able and willing to make the required study visit
- Able and willing to give consent and follow study instructions
- An indication to undergo laser peripheral iridotomy (narrow angles, occludeable angle at risk of acute angle closure, pupil block condition, chronic angle closure, pigment dispersion syndrome)
Key exclusion criteria (5 listed)
- Previous intraocular surgery
- Best corrected visual acuity worse than 20/40
- Asymmetrical ptosis of more than 2mm
- Any active intraocular inflammation
- Acute attack of angle closure glaucoma
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 |
|---|---|---|
| Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laserAlso: Nd:YAG LaserThis device is used to perform the peripheral iridotomy on all patients. It is a standard of care approved device. | Device | Superior Laser Peripheral Iridotomy, Temporal Laser Peripheral Iridotomy |
| Nd:YAG Laser Peripheral IridotomyAlso: Nd:YAG LPIAfter application of topical anesthetic to the eye undergoing the LPI, the patient is seated at the laser machine. Abraham iridotomy lens filled with a viscous material will be used to facilitate the procedure. The thinnest area of the iris quadrant treated will be chosen. Nd:YAG Laser will be applied until iridotomy is opened satisfactory. | Procedure or surgery | Superior Laser Peripheral Iridotomy, Temporal Laser Peripheral Iridotomy |
Primary outcome
Presence of Linear Dysphotopsia
Time frame: Baseline (Time =0),1 month
The change in presence of linear dysphotopsia from baseline (prior to intervention) to 1 month after the Nd:YAG laser intervention is performed.
3 secondary outcomes
Presence of Visual Dysphotopsia
Time frame: Baseline (Time = 0), 1 month
Pain Experienced
Time frame: Procedure (Time = 0)
Nd:YAG Laser Power Used
Time frame: Procedure (Time = 0)
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 13 Feb 2013.
- Background: PubMed 6548087Khodadoust AA, Arkfeld DF, Caprioli J, Sears ML. Ocular effect of neodymium-YAG laser. Am J Ophthalmol. 1984 Aug 15;98(2):144-52. doi: 10.1016/0002-9394(87)90348-5.
- Background: PubMed 1961641Murphy PH, Trope GE. Monocular blurring. A complication of YAG laser iridotomy. Ophthalmology. 1991 Oct;98(10):1539-42. doi: 10.1016/s0161-6420(91)32091-8.
- Background: PubMed 16148584Spaeth GL, Idowu O, Seligsohn A, Henderer J, Fonatanarosa J, Modi A, Nallamshetty HS, Chieh J, Haim L, Steinmann WC, Moster M. The effects of iridotomy size and position on symptoms following laser peripheral iridotomy. J Glaucoma. 2005 Oct;14(5):364-7. doi: 10.1097/01.ijg.0000177213.31620.02.
- Background: PubMed 1584561Weintraub J, Berke SJ. Blurring after iridotomy. Ophthalmology. 1992 Apr;99(4):479-80. doi: 10.1016/s0161-6420(92)38516-1. No abstract available.
- Background: PubMed 22424576Congdon N, Yan X, Friedman DS, Foster PJ, van den Berg TJ, Peng M, Gangwani R, He M. Visual symptoms and retinal straylight after laser peripheral iridotomy: the Zhongshan Angle-Closure Prevention Trial. Ophthalmology. 2012 Jul;119(7):1375-82. doi: 10.1016/j.ophtha.2012.01.015. Epub 2012 Mar 14.
- Background: PubMed 16228219Chung RS, Guan AE. Unusual visual disturbance following laser peripheral iridotomy for intermittent angle closure glaucoma. Graefes Arch Clin Exp Ophthalmol. 2006 Apr;244(4):532-3. doi: 10.1007/s00417-005-0129-x. Epub 2005 Oct 14. No abstract available.
- Derived from this study: PubMed 24531024Vera V, Naqi A, Belovay GW, Varma DK, Ahmed II. Dysphotopsia after temporal versus superior laser peripheral iridotomy: a prospective randomized paired eye trial. Am J Ophthalmol. 2014 May;157(5):929-35. doi: 10.1016/j.ajo.2014.02.010. Epub 2014 Feb 14.
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.
Iqbal Ike K Ahmed, MD principal investigator
University of Toronto, Toronto, Canada. University of Utah, Salt Lake City, USA
Vanessa Vera, MD study director
University of Toronto, Canada
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser and Nd:YAG Laser Peripheral Iridotomy in people with Narrow Angle Patients at Risk for Angle Closure Glaucoma, run by Credit Valley EyeCare at 1 site in Canada.
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 3 inclusion and 5 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 13 Feb 2013. 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 Canada. 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?
Presence of Linear Dysphotopsia (time frame: Baseline (Time =0),1 month). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT01758237, which also lists 7 linked publications.
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 13 Feb 2013; AzTrials last refreshed its copy on 31 Oct 2026.