Nanobacterial detection in aqueous humor and its effect on postphacoemulsification visual acuity among highly myopic patients.

Abstract

This study aimed to investigate factors affecting visual outcomes after phacoemulsification in highly myopic patients with cataracts, based on the detection of nanobacteria (NB) in aqueous humor. Fifty highly myopic patients with cataracts who underwent phacoemulsification surgery at The First People's Hospital of Ziyang from December 2022 to June 2023 were enrolled. Aqueous humor samples were gathered from patients before surgery, and NB were isolated and cultured from the aqueous humor. They were identified using scanning electron microscopy and transmission electron microscopy. The calcium-phosphorus ratios in NB cultures (NB group) and nanohydroxyapatite (nHA) cultures (nHA group) were determined by energy-dispersive X-ray spectroscopy. Cell inhibition was compared using a CCK-8 assay. The expressions of calcification-related proteins, bone morphogenetic protein 2, osteopontin, apoptosis-related proteins, B-cell lymphoma 2 (Bcl-2), and Bcl-2-associated X protein in cells were examined by western blot. Based on the best-corrected visual acuity (VA) 3 months after surgery, patients were classified into a normal vision (NV) group (best-corrected VA ≥0.3) and an abnormal vision (AV) group (best-corrected VA <0.3). The factors influencing postoperative VA and efficacy were analyzed. Results revealed that the characteristics of the aqueous humor cultures were consistent with the features of NB described in the literature, with NB measuring approximately 90 to 340 nm in transmission electron microscopy. Energy-dispersive X-ray results indicated no remarkable difference in calcium-phosphorus ratios between the NB and nHA groups (p > 0.05), but the NB group exhibited remarkably stronger cell inhibition relative to the nHA group (p < 0.05). Western blot results revealed obviously higher levels of bone morphogenetic protein 2, osteopontin, and Bcl-2-associated X proteins in the NB group compared to the nHA group (p < 0.05), while Bcl-2 expression was sharply lower, with a great difference in the NB group (p > 0.05). The gap in best-corrected VA 1 month after surgery between the NV group (68%) and the AV group (32%) was obvious (p < 0.05). With increasing recovery time, the number of patients with best-corrected VA ≥0.3 at 6 months postoperatively substantially increased (86%). The NB-positive rate in the aqueous humor samples was observably lower in the NV group than the rate in the AV group (p < 0.05). Univariate logistic regression analysis revealed great differences in age, duration of high myopia, axial length (AXL), corneal astigmatism, incidence of macular disease, and NB-positive rate (p < 0.05). Multivariate logistic regression analysis indicated that AXL and the presence of NB in the aqueous humor were independent factors influencing the postoperative visual prognosis of highly myopic patients with cataracts (p < 0.05). The experimental results signified that NB cultures suppressed cells and, at the cellular level, influenced the visual recovery after surgery by regulating the expression of calcification-related proteins and mitochondrial apoptosis-related proteins. Multivariate logistic regression analysis further confirmed that AXL and the presence of NB in the aqueous humor were independent factors affecting the postoperative visual prognosis. This finding offered strong support for the future development of relevant treatment modalities.