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Dysphotopsia Following Laser Peripheral Iridotomy

This study has been completed.
Sponsor:
Information provided by (Responsible Party):
Iqbal Ike Ahmed, Credit Valley EyeCare
ClinicalTrials.gov Identifier:
NCT01758237
First received: December 20, 2012
Last updated: February 11, 2013
Last verified: February 2013
History of Changes
  Purpose

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.


Condition Intervention
Narrow Angle Patients at Risk for Angle Closure Glaucoma
 Device: Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser
Procedure: Nd:YAG Laser Peripheral Iridotomy

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Treatment
Official Title: Incidence of Visual Symptom Following Laser (Nd:YAG ) Peripheral Iridotomy (LPI) in Relation to Position of LPI

Resource links provided by NLM:

MedlinePlus related topics: Glaucoma
U.S. FDA Resources

Further study details as provided by Credit Valley EyeCare:

Primary Outcome Measures:
  • Presence of Linear Dysphotopsia [ Time Frame: Baseline (Time =0),1 month ] [ Designated as safety issue: No ]
    The change in presence of linear dysphotopsia from baseline (prior to intervention) to 1 month after the Nd:YAG laser intervention is performed.


Secondary Outcome Measures:
  • Presence of Visual Dysphotopsia [ Time Frame: Baseline (Time = 0), 1 month ] [ Designated as safety issue: No ]
    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.

  • Pain Experienced [ Time Frame: Procedure (Time = 0) ] [ Designated as safety issue: No ]
    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.

  • Nd:YAG Laser Power Used [ Time Frame: Procedure (Time = 0) ] [ Designated as safety issue: No ]
    The amount of laser power used on the Nd:YAG laser to perform the intervention.


Enrollment: 214
Study Start Date: January 2008
Study Completion Date: January 2009
Primary Completion Date: January 2009 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Superior Laser Peripheral Iridotomy
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.
 Device: Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser
This device is used to perform the peripheral iridotomy on all patients. It is a standard of care approved device.
Other Name: Nd:YAG Laser
Procedure: Nd:YAG Laser Peripheral Iridotomy
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.
Other Name: Nd:YAG LPI
Experimental: Temporal Laser Peripheral Iridotomy
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.
 Device: Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser
This device is used to perform the peripheral iridotomy on all patients. It is a standard of care approved device.
Other Name: Nd:YAG Laser
Procedure: Nd:YAG Laser Peripheral Iridotomy
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.
Other Name: Nd:YAG LPI

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.

  Eligibility

Ages Eligible for Study:   18 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
Criteria

Inclusion Criteria:

  • 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)

Exclusion Criteria:

  • 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
  Contacts and Locations
Please refer to this study by its ClinicalTrials.gov identifier: NCT01758237

Locations
Canada, Ontario
Credit Valley EyeCare
Mississauga, Ontario, Canada, L5L 1W8
Sponsors and Collaborators
Credit Valley EyeCare
Investigators
Principal Investigator: Iqbal Ike K Ahmed, MD University of Toronto, Toronto, Canada. University of Utah, Salt Lake City, USA
Study Director: Vanessa Vera, MD University of Toronto, Canada
  More Information

Publications:

Responsible Party: Iqbal Ike Ahmed, Principle Investigator, Credit Valley EyeCare
ClinicalTrials.gov Identifier: NCT01758237     History of Changes
Other Study ID Numbers: CVEC-LPI
Study First Received: December 20, 2012
Last Updated: February 11, 2013
Health Authority: Canada: Ethics Review Committee

Keywords provided by Credit Valley EyeCare:
Laser Peripheral Iridotomy
Visual Dysphotopsia
Visual Disturbances
Angle Closure Glaucoma

Additional relevant MeSH terms:
Glaucoma
Glaucoma, Angle-Closure
Ocular Hypertension
Eye Diseases

ClinicalTrials.gov processed this record on May 23, 2013