Dysphotopsia Following Laser Peripheral Iridotomy

Narrow Angle Patients at Risk for Angle Closure Glaucoma Clinical Trial

Official title:

Incidence of Visual Symptom Following Laser (Nd:YAG ) Peripheral Iridotomy (LPI) in Relation to Position of LPI

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT01758237
• Other study ID #: CVEC-LPI
• Status: Completed
• Phase: N/A
• First received: December 20, 2012
• Last updated: February 11, 2013
• Start date: January 2008
• Est. completion date: January 2009

Study information

• Verified date: February 2013
• Source: Credit Valley EyeCare
• Contact: n/a
• Is FDA regulated: No
• Health authority: Canada: Ethics Review Committee
• Study type: Interventional

Clinical 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 produced by the tear film than those covered.

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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 214
• Est. completion date: January 2009
• Est. primary completion date: January 2009
• Accepts healthy volunteers: No
• Gender: Both
• Age group: 18 Years and older

Eligibility

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

Allocation: Randomized, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Treatment

Related Conditions & MeSH terms

• Glaucoma, Angle-Closure
• Narrow Angle Patients at Risk for Angle Closure Glaucoma

Intervention

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.

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.

Locations

Country	Name	City	State
Canada	Credit Valley EyeCare	Mississauga	Ontario

Sponsors (1)

Lead Sponsor	Collaborator
Credit Valley EyeCare

Country where clinical trial is conducted

Canada, 

References & Publications (6)

Chung 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. Epub 2005 Oct 14. — View Citation

Congdon 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. — View Citation

Khodadoust AA, Arkfeld DF, Caprioli J, Sears ML. Ocular effect of neodymium-YAG laser. Am J Ophthalmol. 1984 Aug 15;98(2):144-52. — View Citation

Murphy PH, Trope GE. Monocular blurring. A complication of YAG laser iridotomy. Ophthalmology. 1991 Oct;98(10):1539-42. — View Citation

Spaeth 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. — View Citation

Weintraub J, Berke SJ. Blurring after iridotomy. Ophthalmology. 1992 Apr;99(4):479-80. — View Citation

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	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.	Baseline (Time =0),1 month	No
Secondary	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.	Baseline (Time = 0), 1 month	No
Secondary	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.	Procedure (Time = 0)	No
Secondary	Nd:YAG Laser Power Used	The amount of laser power used on the Nd:YAG laser to perform the intervention.	Procedure (Time = 0)	No