Narrow Angle Patients at Risk for Angle Closure Glaucoma
Conditions
Keywords
Laser Peripheral Iridotomy, Visual Dysphotopsia, Visual Disturbances, Angle Closure Glaucoma
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.
Interventions
DEVICENeodymium-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.
PROCEDURENd: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.
Sponsors
Credit Valley EyeCare
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| 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
| Measure | Time frame | Description |
|---|---|---|
| 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. |
Countries
Canada
Outcome results
None listed