We aimed to elucidate the effects of antimicrobial eye drops used in the perioperative period of ophthalmic surgery on the ocular surface microbiome by metagenomic analysis. Twenty-eight eyes from 15 patients (mean age 74.1 years) with no history of eye drop use within 3 months before cataract surgery were included in this study. Gatifloxacin eye drops were used in all patients in the perioperative period. The antimicrobial eye drops were started 3 days before surgery. They were discontinued after conjunctival sac specimen collection for 2 weeks after the surgery. Conjunctival sac specimens were collected to investigate the alterations in the ocular surface microbiome by meta-16S analysis targeting the V3-V4 region of the bacterial 16S rRNA gene. Principal coordinate analysis showed that the bacterial composition tended to be different before and 2 and 4 weeks after surgery. Individual observations on six eyes showed that the bacterial composition at 12 weeks after surgery was closer to that before surgery than to that at 4 weeks after surgery in two eyes, while the bacterial composition in the remaining four eyes was different at various time points. Before surgery, Firmicutes, Proteobacteria, and Bacteroidetes were predominant; however, 2 weeks after surgery, the proportion of Proteobacteria increased and that of Firmicutes decreased. A similar trend was noticed 4 weeks after surgery, although antibacterial eye drops had been discontinued 2 weeks after surgery. The Shannon–Weaver coefficient showed a decreasing trend at 2-, 4-, and 12-weeks post operation compared to that before operation. The diversity of the microbiome decreased significantly at 2- and 4-weeks after surgery when compared to that before surgery (p < 0.05). The ocular surface microbiome is easily disrupted by antimicrobial eye drops, and it needs recovery time. In such cases, the ocular surface microbiome is presumed to contain many antimicrobial-resistant bacteria. In some cases, it may not recover, and a new microbiome is formed.

Smear microscopic examination and culture of the corneal scrapings are the gold standards for the diagnosis of bacterial keratoconjunctivitis. High-sensitivity molecular biological examinations of the ocular surface specimens are used clinically. However, the results require careful interpretation to avoid the unintentional detection of indigenous bacteria. Results of conventional and state-of-the-art examinations require clinical verification for specificity and sensitivity. In this study, smear microscopic examination, culture, and nanopore sequencing using the MinION of ocular surface specimens from eight clinically diagnosed bacterial keratoconjunctivitis cases were performed and compared. Seven of the eight cases (87.5%) were smear positive and five (62.5%) were culture positive. The former showed the same genus in >60% of the classified reads as one specific bacterium inferred from the smear microscopy when sequenced by the MinION. In two of the three culture-negative cases, the smear-positive images were highly reminiscent of the species comprising most of the MinION sequences. Four of the five culture-positive cases were consistent with the most prevalent bacteria in the sequencing results. Probable contamination among specimens processed on the same day were observed. In conclusion, the microscopic examination of the corneal scraping specimens may be more sensitive and specific than the culture examination. Additionally, although metagenomic analysis using the MinION contributes to more precise medication for bacterial keratoconjunctivitis, contamination can affect the results.

Purpose: To determine the in vitro antimicrobial activity of quinolones against major bacterial isolates from the ocular surface bacterial flora of patients in a tertiary hospital for selection of optimal antibiotic eye drop during the perioperative stage. Methods: The conjunctival sac scraping of 933 patients who underwent ophthalmic surgery was cultivated and bacterial species of the isolates were identified. The minimum inhibitory concentrations (MICs) of gatifloxacin (GFLX), moxifloxacin (MFLX), levofloxacin (LVFX), and tosufloxacin (TFLX) were measured by microdilution methods. The cumulative percentages of MICs of 4 quinolones against major bacteria were calculated. The concentrations of quinolones inhibiting 50% (MIC50) and 90% (MIC90) of the major bacteria were compared. Results: The study mainly included 784 patients scheduled for cataract surgery, 73 for vitrectomy, 30 for corneal transplantation, 30 for conjunctival surgery, 11 for eyelid surgery. The most frequently isolated bacterium was coagulase-negative Staphylococci (CNS) (184 strains), followed by Corynebacterium (107 strains), Staphylococcus aureus (33 strains), Streptococcus (18 strains), and Enterococcus (13 strains). The percentages of methicillin-sensitive CNS isolates for which MIC of GFLX, MFLX, LVFX, and TFLX was 0.06 μg/mL or less were 8.0%, 13.4%, 5.4%, and 63.4%, respectively. Similarly, the percentage for Corynebacterium was 23.0%, 23.0%, 0%, and 35.6%, respectively. MIC50 of TFLX for Streptococcus and Enterococcus showed the lowest values, 0.12 and 0.25 μg/mL, respectively. Conclusions: Among 4 quinolones, TFLX has the highest in vitro antimicrobial activity against major bacterial isolates from the ocular surface bacterial flora of patients in a tertiary hospital.

Background: Rebamipide ophthalmic suspension was launched in Japan in 2012 and is used for the treatment of dry eye. Case Presentation: We report two cases of orbital abscess, which resulted from dacryocystitis that occurred after administration of rebamipide ophthalmic suspension. Computed tomography images showed an eyeball deformity in one case and exophthalmos in the other. In both cases, light microscopy, scanning electron microscopy and energy dispersive X-ray examinations revealed lacrimal sac concretions, which contained calcium phosphate crystals that were surrounded by microorganisms. Lacrimal sac concretion removal from the lacrimal sacs during dacryocystorhinostomies was performed on both patients. Although the postoperative outcome was favorable in one case, vision was lost in the other case due to the development of retinal artery occlusion as a complication of the orbital abscess, despite lacrimal sac concretion removal and administration of antimicrobials. Conclusions: This is the first case report to highlight that rebamipide ophthalmic suspension can cause an orbital abscess via development of lacrimal sac concretion. Ophthalmologists should be aware that rebamipide ophthalmic suspension might induce the formation of concretion in the lacrimal sac.

The present study elucidated the pathogenesis of allergic symptoms (AS) related to contact lens (CL) wear by assaying CL care solutions in lens storage cases and tears from subjects with AS using molecular biology techniques. A total of 15 CL storage cases were collected from subjects with AS (n=9) and healthy, asymptomatic control CL wearers (n=6). Bacterial populations in CL care solutions and tears were assayed by culture and 16S rDNA sequencing. Histamine levels in tears were measured by high‑performance liquid chromatography. Western blot analysis was performed to identify the bacteria recognized by tear IgE from subjects with AS. No significant differences were found in the culture results between the subjects with AS and asymptomatic subjects. Histamine was detected in 2 subjects with AS. Meta‑16S rDNA sequencing identified a cluster of 4 subjects with AS that were distinguished from others by principal coordinate analysis. Detailed population analysis revealed that the abundance of Gram‑positive bacteria in the microbiomes of CL care solutions used by the subjects with AS were higher than those of asymptomatic subjects (42.24±9.47 vs. 16.85±22.76% abundance). Among these, Streptococcus was the dominant genus (12.1‑18.3% abundance). Tear microbiome analysis revealed that the abundance of Streptococcus in the subjects with AS was significantly higher than that in other subjects (19.02±5.50 vs. 3.08±3.35%, P<0.01). Western blot analysis demonstrated that the tear IgE in all subjects with AS reacted with Streptococcus (100%), but not with Staphylococcus. On the whole, these results provide novel insight into the pathogenesis of AS and identify Streptococcus as an important factor in AS associated with CL wear.

BACKGROUND: Subtenon injection of triamcinolone acetonide (STTA) has been widely adopted in the clinical setting of ophthalmology and its infectious complications are rare. However, orbital abscess following STTA has been reported in seven cases. Furthermore, although eye infections due to Exophiala species are uncommon, there have been 19 cases to date. E. jeanselmei, E. phaeomuriformis, E. werneckii, and E. dermatitidis have been reported to cause human eye infections; however, to the best of our knowledge, orbital abscess caused by E. dermatitidis has not yet been reported. We describe the first documented case of fungal orbital abscess caused by E. dermatitidis following STTA. We also review the related literature of orbital abscess following STTA, as well as eye infections caused by the four Exophiala species. CASE PRESENTATION: The patient was a 69-year-old Japanese woman with diabetic mellitus. She had a macular oedema in her right eye, which occurred secondary to branch retinal vein occlusion. An orbital abscess caused by E. dermatitidis occurred 4 months after the second STTA for the macular oedema, which was successfully treated by a surgical debridement and systemic administration of voriconazole. CONCLUSIONS: Our findings in the patient and from our literature survey caution ophthalmologists to the fact that STTA can cause fungal orbital infections, especially in diabetic patients. Furthermore, surgical treatment is one of the most important risk factors.

Intraoperative optical coherence tomography (iOCT) is widely used in ophthalmic surgeries for cross-sectional imaging of ocular tissues. The greatest advantage of iOCT is its adjunct diagnostic efficacy, which facilitates to decision-making during surgery. Since the development of microscopic-integrated iOCT (MIOCT), it has been widely used mainly for vitreoretinal and anterior segment surgeries. In corneal transplantation, MIOCT allows surgeons to visualise structure underneath the turbid and distorted cornea, which are impossible to visualise with a usual microscope. Real-time visualisation of hard-to-see area reduces the operation time and leads to favorable surgical outcomes. The use of MIOCT is advantageous for a variety of corneal surgical procedures. Here, we have reviewed articles focusing on the utility of iOCT  and MIOCT in penetrating keratoplasty, deep anterior lamellar keratoplasty, Descemet stripping automated endothelial keratoplasty, and Descemet membrane endothelial keratoplasty. The applications of MIOCT to corneal surgery in terms of surgical education for trainees, emergency surgery, and novel surgery are also discussed, with our cases performed using RESCAN® 700.

ヒト臍血管内皮細胞の培養上清においてPeroxisome proliferator-activated receptor gamma (PPARγ)がエスソソーム分画に検出され、核内蛋白であるPPARγが細胞外液に分泌されうることを示した。増殖膜中のPPARγ遺伝子や前房水・硝子体中のPPARγ蛋白濃度はコントロールと比べ増殖糖尿病網膜症で有意に高値であった。また、前房水・硝子体中のPPARγ濃度はvascular endothelial growth factor濃度や糖尿病網膜症の病期と有意に正の相関を示した。以上より、PPARγが糖尿病網膜症治療の標的となりうることが示唆される。