Dysphotopsia Following Laser Peripheral Iridotomy

Not Applicable

Completed

• Conditions: Narrow Angle Patients at Risk for Angle Closure Glaucoma

• Registration Number: NCT01758237
• Lead Sponsor: Credit Valley EyeCare

Brief 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 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 Timeline

• Study Start: 2008-01
• Primary Completion: 2009-01
• Study Completion: 2009-01
• Study First Submitted: 2012-12-20
• Study First Submitted QC: 2012-12-31
• Study First Posted: 2013-01-01
• Status Verified: 2013-02
• Last Update Submitted: 2013-02-11
• Last Update Posted: 2013-02-13

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 214

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

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Primary Outcome Measures

Name	Time	Method
Presence of Linear Dysphotopsia	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.

Secondary Outcome Measures

Name	Time	Method
Presence of Visual Dysphotopsia	Baseline (Time = 0), 1 month	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	Procedure (Time = 0)	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	Procedure (Time = 0)	The amount of laser power used on the Nd:YAG laser to perform the intervention.

Trial Locations

Locations (1)

Credit Valley EyeCare; 🇨🇦 Mississauga, Ontario, Canada