Abstract
Purpose :
To evaluate whether perioperative autonomic function and pain sensitivity predicts severity of dry eye (DE) symptoms 6 months after laser-assisted in situ keratomileusis (LASIK).
Methods :
Secondary analysis of prospective, masked, randomized single center study. Patients were treated with either pregabalin (28 doses of oral solution of pregabalin 150 mg BID, first dose prior to surgery) vs. placebo solution without pregabalin. All subjects underwent testing of autonomic function and pain sensitivity prior to surgery. This included temperature measured over the right forehead, blood pressure, pain thresholds to pin prink over the forehead and forearm, temporal summation to pin prink over the forearm, conditional pain modulation responses, and presence of after-sensations, defined as pain 15 seconds after the stimulus was removed over the forearm. The primary outcome was severity of DE symptoms, assessed via the Dry Eye Questionnaire 5 (DEQ5), 6 months after surgery. Secondary outcomes were ocular surface examinations, which included Inflammadry (Quidel, San Diego), tear break up time, corneal staining, Schirmer score, and meibomian gland assessment. All metrics were assessed at baseline and 6 months after surgery.
Results :
42 of 43 individuals completed the final visit. At 6 months, the pregabalin group had a higher frequency of DE symptoms (57% vs. 33% with Dry Eye Questionnaire 5 (DEQ5) score ≥6), but the difference was not statistically significant. Several measures of autonomic function correlated with DEQ5 scores 6 months after surgery including a higher surface temperature over the forehead (rho 0.31, p=0.04), lower systolic blood pressure (rho -0.34, p=0.03), and lower diastolic blood pressure (rho -0.29, p=0.07). Temporal summation and conditioned pain modulation values were not significantly associated with DE symptoms 6 months after surgery. However, the presence of after sensations was a significant predictor of symptoms at 6 months (DEQ5 scores:8±2 in those with after-sensations versus 5±5 in those without after-sensations, p=0.02). Ocular signs at basline and at 6 months were similar between the groups and did not correlate with DE symptoms.
Conclusions :
Autonomic measures suggestive of increased parasympathetic tone and metrics suggestive of heightened pain sensitivity correlated with DE symptom severity 6 months after LASIK surgery.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.