AbstractBackgroundThis study aimed to evaluate the impact of PreserFlo Microshunt on the ocular surface, focusing on both objective and subjective parameters.MethodsProspective‐observational study on 48 eyes undergoing PreserFlo Microshunt implantation, standalone or combined with phacoemulsification. At baseline, 1‐month, 6‐months and 12‐months post‐operative follow‐ups, we performed Ocular Surface Disease Index (OSDI) questionnaire, Schirmer's test (ST), Tear‐film break‐up time (TBUT), fluoresceine staining (FS), tear osmolarity and minimum corneal epithelial thickness (Epi‐Thk_MIN.) measurements.ResultsOSDI score improved from 37.43 ± 17.49 at baseline, to 24.13 ± 12.55 at 1‐month (p = 0.003) and to 12.89 ± 8.54 and 13.09 ± 10.22 at 6‐months and 12‐months (p < 0.0001). TBUT and ST, in a similar way, non‐significantly increased at 1‐month, but then improved at 6‐months and 12‐months (p < 0.05 for both). Tear osmolarity significantly decreased from 308.2 ± 7.3 mOsm/L at baseline, to 303.3 ± 8.2 mOsm/L, 295.6.2 ± 7.0 mOsm/L and 297.6 ± 6.8 mOsm/L at 1‐month, 6‐months and 12‐months (p < 0.05 for all). Epi‐Thk_MIN was stable when comparing baseline (44.9 ± 5.7 μm) and 1‐month (p = 0.28), and successively increased in 6‐months (47.8 ± 5.5 μm, p = 0.02) and 12‐months (48.0 ± 3.6 μm, p = 0.01). In subgroup analysis, OSDI score and tear osmolarity were significantly higher at 1‐month in combined group compared to standalone group (p = 0.03 and p = 0.02, respectively), but reaching comparable values in successive follow‐ups. Further, Oxford scale grades for FS were significantly improved when comparing baseline–6‐months and baseline–12‐months.ConclusionPreserFlo implantation improved ocular surface subjective symptoms, increased TBUT and ST, and reduced FS, highlighting the potential benefits of this surgical intervention. Moreover, we reported significant improvements of tear osmolarity and corneal epithelium.