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David Benjamin Kay, Robert Kay, Jeffrey Kay; Comparison of Ocular Sensation in Right vs. Left Eyes Undergoing Glaucoma Laser Surgery. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4980. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Numerous studies have shown that the right side of the brain plays a significant role in processing pain and emotion, which may explain the lower pain threshold found in many left-sided anatomic structures. This has yet to be evaluated with regard to the eyes, however. In this study, we evaluate subjective ocular sensitivity in right versus left eyes in patients undergoing bilateral glaucoma laser surgery.
This observational survey study consisted of 396 eyes of 198 patients requiring bilateral glaucoma laser surgery between March 2015 and May 2016. Treatments included bilateral ALT, SLT, LPI, and iridoplasty. Laser settings were constant for all treatments with the exception of iridoplasty, in which power was titrated to optimize efficacy. Following each surgery, patients were asked to complete a questionnaire which included a visual analog scale (0 to 10) from which they could rate the discomfort they experienced during treatment. Additional characteristics such as age, gender, handedness, pre- and post-operative IOP, and eye color were also evaluated. The eye treated first was randomized for each patient, and second eyes were treated within one month of the first.
Of the 198 patients, 123 (62%) were female. Thirty-five (18%) underwent ALT, 60 (30%) underwent SLT, 98 (48%) LPI, and 7 (4%) iridoplasty. Left eyes had a statistically higher mean sensitivity rating compared to right eyes for ALT (0.3 ± 0.6 OD vs. 2.0 ± 2.1 OS, p < 0.01), SLT (1.0 ± 1.3 OD vs. 1.9 ± 1.7 OS, p < 0.01), and LPI (1.5 ± 1.4 OD vs. 1.8 ± 1.5 OS, p < 0.01). There was a trend towards a higher mean sensitivity in left eyes undergoing iridoplasty, although this did not reach statistical significance. No difference was found between discomfort levels reported by men and women for all laser types. Patients with dark irides tended to report more discomfort compared to patients with lighter eyes.
Consistent with other anatomic structures, left eyes may have a lower pain threshold compared to right eyes. This may be related to right cortical/subcortical structures having a greater influence in processing pain and emotion, or may be related to other anatomic factors. Our study did not show a difference in sensitivity between men and women, but patients with dark irides did tend to report greater discomfort with equivalent laser settings, likely attributable to increased laser energy absorption.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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