Dysphotopsia Associated With Laser Peripheral Iridotomy
Dr. Nathan M. Radcliffe
One procedure that is performed with frequency by both glaucoma specialist and comprehensive ophthalmologist is the laser peripheral iridotomy, typically indicated to eliminate pupillary block in primary angle closure suspects. The purpose of the laser peripheral iridotomy is to equalize the pressure between the anterior and posterior chambers, and the procedure may be performed with a Nd:YAG or argon style laser, or a combination of the two.
While side effects of the procedure can include inflammation or bleeding, dysphotopsia is perhaps the most concerning potential side effect, as it can be challenging if not impossible to eliminate, although it will frequently resolve on its own. Despite the fact that the visual impairment from dysphotopsia is minimal compared to the significant functional loss that can occur following acute or chronic angle closure glaucoma, all side effects deserve our attention. Dr. George Spaeth and colleagues1 have published that up to 4% of patients undergoing the iridotomy procedure may experience dysphotopsia. From the initial sample of eyes, the authors concluded that the likelihood of dysphotopsia was higher in patients who have partially or completely exposed iridotomies compared with complete eyelid coverage.
Recently, Dr. Ike Ahmed and colleagues performed a randomized, prospective, masked, fellow eye comparative clinical trial that sought to determine whether the location of the peripheral iridotomy, superior versus temporal, was associated with a higher or lower rate of dysphotopsia.2 They included over 200 patients undergoing bilateral iridotomy and randomly assigned them to have a superior laser in one eye and a temporal laser in the other. The authors determined that 10.7% of those with the superior iridotomy experience new onset linear dysphotopsia while only 2.4% of those with a temporal iridotomy experience this side effect. Bleeding occurred in about 10% of patients in either group. The amount of eyelid covering the iridotomy did not seem to prevent dysphotopsia, and it was notable that a temporal iridotomy was more painful.
In summary, this important study by Dr. Ahmed and colleagues provides new helpful information regarding this photopsia after laser peripheral iridotomy and may have implications for where we place our laser. Regardless, it is worth taking the time to discuss dysphotopsia with patients prior to the iridotomy.
1. 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;157:929-35.
2. Spaeth GL, Idowu O, Seligsohn A, Henderer J, Fonatanarosa J, Modi A, Nallamshetty HS, Chieh J, Haim L, Steinmann WC, Moster M. J. The effects of iridotomy size and position on symptoms following laser peripheral iridotomy. Glaucoma. 2005;14:364-7.
Dr. Nathan M. Radcliffe is the director of the glaucoma service and a clinical assistant professor at
New York Univeristy Langone Ophthalmology Associates and is a cataract and glaucoma surgeon at
the New York Eye Surgery Center.