## 3 Results
### Ocular Symptoms and Signs at Six Months after LASIK  
The frequency of mild or greater DE symptoms after six months returned to levels similar to those observed at baseline (45% of the population had DEQ5 \(\geq\) 6) (Table 3). Also, as seen at 3-month follow-up, more individuals randomized to the pregabalin group presented with DE symptoms than those patients randomized to placebo (57% vs. 33%; \(p=0.12\)), but this difference was not statistically significant (Figure 2). The difference between the groups was 24%, and the 95% confidence interval ranged from \(-\)53% to +5%. Ocular signs were similar between the two groups at six months follow-up. More individuals in the pregabalin group used artificial tears at six months, but the difference was again not statistically significant (57% vs. 48%, \(p=0.54\)). In total, three patients (two in the pregabalin group and one in control) had punctal plugs placed by six months. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Pregabalin** & **Control** & \(p\)**-Value** \\ \hline Number & 21 & 22 & \\ \hline Eye symptoms & & & \\ \hline DEQ5, mean (SD), range 0-22 & 6.6 (3.9) & 4.7 (4.4) & 0.14 \\ \hline DEQ5, mild symptoms \(\geq\)6, \(n\) (\%) & 14 (67\%) & 10 (46\%) & 0.16 \\ \hline DEQ5, severe symptoms \(\geq\)12, \(n\) (\%) & 1 (5\%) & 2 (9\%) & 1.00 \\ \hline Change in DEQ5 from baseline, mean (SD) & 1.1 (3.9) & 0.4 (4.0) & 0.54 \\ \hline OSDI, mean (SD), range 0-100 & 11.9 (11.5) & 11.0 (16.6) & 0.84 \\ \hline Change in OSDI from baseline, mean (SD) & \(-\)0.01 (15.6) & 2.0 (15.1) & 0.67 \\ \hline Ocular pain, worst over one week recall, mean (SD), range 0-10 & 1.25 (1.52) & 0.50 (1.01) & 0.07 \\ \hline Ocular pain, average over one week recall, mean (SD), range 0-10 & 0.85 (0.27) & 0.27 (0.55) & 0.07 \\ \hline Sf-MPQ sensory, mean (SD), range 0-33 & 0.65 (1.23) & 0.36 (0.66) & 0.35 \\ \hline Sf-MPQ affective, mean (SD), range 0-12 & 0.30 (0.66) & 0.18 (0.39) & 0.48 \\ \hline Intensity of burning over one day recall, mean (SD), range 0-10 & 0.15 (0.67) & 0.64 (1.76) & 0.24 \\ \hline Intensity of wind sensitivity one day recall, mean (SD), range 0-10 & 0.70 (1.56) & 0.36 (0.95) & 0.40 \\ \hline Intensity of light sensitivity one day recall, mean (SD), range 0-10 & 0.90 (1.83) & 0.64 (1.62) & 0.62 \\ \hline NPSI-Eye total, mean (SD), range 0-100 & 2.70 (4.55) & 1.86 (4.07) & 0.53 \\ \hline \hline \end{tabular} SD = Standard deviation, DEQ5 = Dry Eye Questionnaire 5, OSDI = Ocular Surface Disease Index, sf-MPQ = short form McGill Pain Questionnaire, NPSI-Eye = Neuropathic Pain Symptom Inventory for the eye.  
\end{table} 
Table 2: Ocular symptoms at three months post-LASIK, by treatment assignment. Figure 2: Comparison of Ocular Symptom Scores at Baseline and 6-Months. DEQ5 = Dry Eye Questionnaire 5, OSDI = Ocular Surface Disease Index, NRS = Numerical Rating Scale for ocular pain averaged over one week recall, NPSI-Eye = Neuropathic Pain Symptom Inventory modified for an eye. To examine the validity of our outcome measures, we ran Pearson correlations to assess the strength of association between measures of eye pain intensity (Table 4). The three pain indices (NRS, NPSI-Eye, sf-MPQ) were strongly correlated with one another (average \(r=0.66\)). The two overall symptom indices (DEQ5, OSDI) were weakly correlated (\(r=0.34\)), although this is not surprising given that the two questionnaires measure different aspects of DE. The DEQ5 focuses on symptoms (dryness, discomfort, tearing), while the OSDI also incorporates DE triggers and impact on everyday activities.