Clinical trial NCT01758237: Dysphotopsia Following Laser Peripheral Iridotomy
Official title: Incidence of Visual Symptom Following Laser (Nd:YAG ) Peripheral Iridotomy (LPI) in Relation to Position of LPI
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Narrow Angle Patients at Risk for Angle Closure Glaucoma
Keywords: Laser Peripheral Iridotomy
Visual Dysphotopsia
Visual Disturbances
Angle Closure Glaucoma
Lead sponsor: Credit Valley EyeCare
Sponsor class: INDUSTRY
First posted: 2013-01-01
Enrollment: 214
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: TREATMENT

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.

Eligibility 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

Primary outcomes:
measure: Presence of Linear Dysphotopsia
timeFrame: Baseline (Time =0),1 month
Secondary outcomes:
measure: Presence of Visual Dysphotopsia
timeFrame: Baseline (Time = 0), 1 month
measure: Pain Experienced
timeFrame: Procedure (Time = 0)
measure: Nd:YAG Laser Power Used
timeFrame: Procedure (Time = 0)
Other outcomes:
Locations:
city: Mississauga
country: Canada
facility: Credit Valley EyeCare
state: Ontario
Study officials:
affiliation: University of Toronto, Toronto, Canada. University of Utah, Salt Lake City, USA
name: Iqbal Ike K Ahmed, MD
role: PRINCIPAL_INVESTIGATOR
affiliation: University of Toronto, Canada
name: Vanessa Vera, MD
role: STUDY_DIRECTOR
References:
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. doi: 10.1016/0002-9394(87)90348-5.
citation: Murphy 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.
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. doi: 10.1097/01.ijg.0000177213.31620.02.
citation: Weintraub J, Berke SJ. Blurring after iridotomy. Ophthalmology. 1992 Apr;99(4):479-80. doi: 10.1016/s0161-6420(92)38516-1. No abstract available.
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.
citation: 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. doi: 10.1007/s00417-005-0129-x. Epub 2005 Oct 14. No abstract available.
citation: Vera 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.