BackgroundDiagnostic vitrectomy is an important method for evaluating uveitis, and its diagnostic utility is high regardless of whether the uveitis is infectious or non-infectious. The course of diagnostic vitreous surgery with 27-gauge pars plana vitrectomy and perioperative complications is reported.MethodsAn observational retrospective study of patients who underwent 27-gauge diagnostic vitrectomy due to atypical intraocular inflammation was conducted. The final diagnosis rate, complications due to surgery, preoperative visual acuity, and postoperative visual acuity (1 month and 6 months after surgery) were examined retrospectively.ResultsDiagnostic vitreous surgery was performed in 32 patients and 35 eyes (14 males and 18 females, age 14–85 years, median 67 years) during the study period. The average operation time was 52 min for 19 eyes with cataract surgery and 35 min for 16 eyes without cataract surgery. Preoperative log(minimum angle of resolution [MAR]) visual acuity was 0.84 ± 0.87, 1-month postoperative logMAR visual acuity was 0.41 ± 0.55 (p = 0.004, n = 28), and 6-month postoperative average logMAR visual acuity was 0.45 ± 0.73 (p = 0.012, n = 15). The diagnosis was made by diagnostic vitrectomy in 19 cases (54%). Postoperative complications were observed in 2 of 35 postoperative patients (5%); one involved increased intraocular pressure, and the other case involved vitreous hemorrhage of the eye, necessitating reoperation.ConclusionDiagnostic 27-gauge vitrectomy could be effective for evaluating intraocular inflammation.