Study of the Correlation Between Severity of Endophthalmitis and Posterior Vitreous Detachment Using a Rabbit Endophthalmitis Model

PURPOSE: We have reported that the absence of posterior vitreous detachment (PVD) is related to the onset and severity of infectious endophthalmitis, based on clinical experience. To demonstrate clinical findings in animal models, we created endophthalmitis models for the presence or absence of PVD and examined differences in severity. METHOD: We estimated a rabbit infectious eye model with and without PVD using Pseudomonas aeruginosa (PVD(+) and PVD(−) groups). After injection of bacteria inoculation for 3, 6, 12, and 24 hours, we evaluated the clinical score of the anterior chamber (n = 14). Removing the vitreous and retina from the enucleated eyeballs, the number of bacteria was counted using each specimen (n = 12). In addition, the number of inflammatory cells approximately 3 mm(2) around the optic disc and histopathologic grading of intraocular inflammation was compared from histopathologic images (n = 7). Electroretinogram (ERG) was performed in experimentally infected rabbit eyes in both groups at three times after injection of the bacterial suspension. RESULTS: There was no difference between the two groups in the clinical score of the anterior chamber of each time phase, but the bacterial cultures showed significantly fewer bacteria in the PVD(−) group 24 hours after bacterial inoculation (P < 0.05). Furthermore, the number of inflammatory cells was significantly less in the PVD group (P < 0.05). As a result of ERG, the decreases of a- and b-waves in amplitude were significantly greater in the PVD(−) group than in the PVD(+) group. CONCLUSIONS: The present study confirms using animal models that the absence of PVD contributed to the severity of bacterial endophthalmitis.