Diplopia underrecognized in patients with medically and surgically treated glaucoma

April 15, 2017

A study of 195 adult patients who received medical or surgical treatment for glaucoma indicates that diplopia may be underrecognized in those patients — and standardized use of the diplopia questionnaire to ascertain patient symptoms may be helpful.

Cheryl L. Khanna, M.D., Jonathan M. Holmes, M.D., David A. Leske, M.S., and Philip Y. Sun, M.S., at Mayo Clinic's campus in Rochester, Minnesota, conducted the cohort study to identify the prevalence, type and etiology of diplopia in patients with glaucoma who were treated medically and surgically.

"Diplopia has been reported as a complication of glaucoma treatment, but has not been rigorously studied across the spectrum of medical and surgical treatment for glaucoma. Nor has it been assessed prospectively with an instrument specifically designed to assess diplopia," says Dr. Khanna. Study results were published in Ophthalmology in 2016.

All patients in the cohort completed the diplopia questionnaire, a patient-reported outcome measure to assess symptoms of diplopia in specific gaze positions. In this study, the researchers defined the presence of diplopia as the patient indicating diplopia with a frequency of sometimes, often or always when looking straight ahead in the distance or when reading or when doing both on the diplopia questionnaire. Diplopia was reported in 41 patients (21 percent) in the cohort.

Dr. Khanna, a glaucoma specialist, and Dr. Holmes, a strabismus specialist, determined the type and etiology of diplopia by joint review of the entire medical record with specific attention to the characteristics and the time course of diplopia and strabismus. Results indicate:

  • Binocular diplopia attributable to the glaucoma procedure was present in 11 of 47 (23 percent) patients after glaucoma drainage device (GDD) surgery (95 percent confidence index, or CI; 12 to 38 percent), which was significantly greater than in patients post-trabeculectomy (two of 61, or 3 percent, 95 percent CI; 0.4 to 11 percent; P = 0.002).
  • The most common type of strabismus associated with binocular diplopia attributable to glaucoma surgery was hypertropia: 10 out of 11 patients who received GDD surgery and two out of two patients who received trabeculectomy.
  • Monocular diplopia was found in a similar proportion of patients who received medical treatment, were post-trabeculectomy and were post-GDD surgery: Four of 87 (5 percent), four of 61 (7 percent), and two of 47 (4 percent) respectively.
  • Binocular diplopia not attributable to surgery was found in similar proportions of patients who received GDD surgery, trabeculectomy and medical treatment: Three of 47 (6 percent), five of 61 (8 percent), and 10 of 87 (11 percent) respectively.

Diplopia occurred in 16 percent of the control group (patients treated medically for glaucoma), which reflects the occurrence of common strabismus conditions (convergence insufficiency, adult-onset distance esotropia and small-angle hypertropia) in this population of mostly older adults.

"Diplopia was more commonly seen in patients after GDD surgery, and specifically in patients who received Baerveldt BG 101-350, rather than patients who received trabeculectomy. Diplopia is more common in patients with multiple and bilateral GDD surgery. The prevalence of monocular diplopia and binocular diplopia unrelated to glaucoma surgery was similar among medical and surgical groups," says Dr. Khanna. "That outcome indicates that it is important to counsel patients on the higher occurrence of diplopia associated with GDD surgery.

"The diplopia questionnaire is valuable for use in studies reporting diplopia and strabismus. Use of this standardized tool to assess diplopia may be helpful in the routine care in patients with glaucoma. It may also be helpful for patients undergoing glaucoma surgery to have a standardized assessment of diplopia and strabismus, both before and after surgery. Without a standard instrument, providers may not broach the topic of diplopia with patients in routine follow-up appointments and as a result, diplopia may not be reported consistently in the medical record."

For more information

Sun PY, et al. Diplopia in medically and surgically treated patients with glaucoma. Ophthalmology. 2017;124:257.

Holmes JM, et al. Quantifying diplopia with a questionnaire. Ophthalmology. 2013;120:1492.