Monitoring the transition from corneal ulceration to healed scar using a Scheimpflug tomography-based densitometry.

PURPOSE: To compare corneal haze between active ulcer and healed scarring using a Scheimpflug densitometry. MATERIALS AND METHODS: A prospective longitudinal study enrolled 30 patients (30 eyes) with ulcerative keratitis (UK). Each subject's corneal optical density (COD) was measured with a Scheimpflug corneal densitometry, Pentacam® AXL (Oculus GmbH, Wetzlar, Germany), at the active ulcerative and complete scarring stage. The COD data were analyzed through distinct methods (inbuilt, sorted annular partitions, and ulcer-matching densitometric maps). We compared different CODs to select the better index for clinically monitoring the transition from corneal ulceration to healed scar. RESULTS: The CODs of the periphery (P = 0.0024) and outside of the active ulcer (P = 0.0002) significantly decreased after scarring. Partitioning the cornea into different depths and annular zones, the anterior layer, center layer, and the 2-6 mm annular zone had a more remarkable COD decrease after scar formation. The 3rd-sorted COD in the anterior layer revealed the highest area under the receiver-operating characteristic curves (0.709), in which 90% of subjects had COD reduction during the ulcer-to-scar transition. CONCLUSIONS: Aside from subjective judgment based on clinical signs, the Scheimpflug tomography-based densitometry could provide objective and efficient monitoring of the corneal opacity evolution in UK patients. Because the 3rd-sorted annular COD is a better index than the inbuilt or mapping CODs in differentiating active ulcers from healed scars, this COD could be a clinically promising parameter to monitor the progression of UK patients.

Tear Proteomics Approach to Distinguishing Primary from Secondary Sjögren's Syndrome for Dry Eye Patients with Long-Term Instillation of Eyedrops.

The diagnosis and monitoring of Sjögren syndrome (SS) is often difficult, requiring a multidisciplinary approach with invasive procedures. Our aim is to elucidate the tear protein alterations of dry eye disease (DED) with primary SS (pSS) and secondary SS (sSS) with the long-term instillation of eyedrops. We collected clinical demographics and tear fluid (TF) samples from DED patients with no autoimmune diseases (non-SS-DED), pSS-DED, and sSS-DED patients, followed by TF screening with tandem mass tagging-labeling gel-free proteomics assay. Bioinformatic analysis via Ingenuity Pathway Analysis was used to identify functional pathways and interacting networks. Validation of candidate proteins with enzyme-linked immunosorbent assay on the tear samples was done. The top functional pathways of the two comparisons (sSS-DED vs. pSS-DED and sSS-DED vs. non-SS-DED) were both associated with inflammation and stress-related signaling. After constructing an interaction network model with the selected candidate proteins, five proteins were identified. A Disintegrin and Metalloproteinase domain-containing protein 10 (ADAM10) was found to be an important candidate biomarker in all groups, followed by epidermal growth factor (EGF) in TF. This study revealed novel DED markers, ADAM10 and EGF, in differentiating between primary and secondary SS patients from tears by in-depth proteomic analysis.

Grading reliability of the tear film viscosity examination.

PURPOSE: To assess the reliability of a tear film (TF) viscosity video grading system. METHODS: Thirty-four dynamic TF viscosity videos were obtained by a clinically available TF analyzer and objectively sorted according to the movement speed of three arbitrary reflective light particles. A 4-grade system was constructed on a specially designed window for simultaneous comparison with the three standard videos. Two masked graders were invited to grade these videos under a randomized procedure. Observer reliabilities were determined by Spearman's correlation analysis and Bland-Altman agreement analysis. RESULTS: For this four-grade system, the intra-observer correlation was very strong in the two graders (ρ = 0.96 and 0.82; both P < 0.0001). However, the inter-observer correlation showed moderate strength in normal playback speed (ρ = 0.53, P = 0.002 and ρ = 0.52, P = 0.003 for 1st and 2nd gradings, respectively). In slower playback videos, the inter-observer correlation of the two graders was higher (ρ = 0.70 and P < 0.0001) when reduced to 0.8-times playback speed. Moreover, the 0.8-times mode was also significantly better than normal playback mode (P = 0.0204) in terms of inter-observer agreement. CONCLUSIONS: The dynamic 4-grade system has an excellent intra-observer reliability and a good inter-observer reliability under 0.8-times playback speed. The grading system established in this study provides a promising solution for rapidly determining the level of TF viscosity.

Axial length of cataract eyes: a comparison of two cohorts over a span of 10 years apart.

BACKGROUND: To assess the associations of axial length with age-related cataract within a span of 10 years in an Asian population in southern Taiwan. METHODS: A retrospective cohort study examined 960 adults who underwent cataract surgery at the Kaohsiung Chang Gung Memorial Hospital in year 2008 and year 2018. Axial length was assessed with the ultrasound biometry and/or the Zeiss IOLMaster. Eyes with prior blunt eye trauma or had underwent vitrectomy operations were excluded. The significance of the changes in axial length between the two cohorts was determined after performing age-matched analyses. Due to utilization of ultrasound biometry and/or Zeiss IOLMaster, axial length corrections with our mean difference in measurement results, which were similar to previous studies on comparison between the two measurement tools, were carried out. RESULTS: Axial length showed an age-related elongation in 10-year cross-sectional data, from a mean of 23.65 ± 1.80 mm in year 2008 to a mean of 24.30 ± 1.90 in year 2018 (p = 0.003). Patients with high myopia (axial length > 26 mm) increased significantly over the 10-year period from 8.1 to 16 % (p < 0.001). A birth cohort effect on axial length was evident as the axial lengths of year 2008 cohort were shorter than the 2018 cohort when they were in the same operation age group. In particular, persons born after the 1960s demonstrated a predominant increase in axial length in both cohorts. CONCLUSIONS: Our study confirms a trend in increase of axial myopia, especially high myopias, over the 10-year period. A novel finding of this study was discovering a birth cohort effect on axial length, especially in persons born after the 1960s in southern Taiwan.

The severity of visual field defect and the defective angles of localized retinal nerve fiber layer using a novel approach.

BACKGROUND/PURPOSE: A modified novel analytical method for evaluating photographic retinal nerve fiber layer defect (RNFLD) was developed for the purpose of estimating the severity of early glaucomatous eyes. This new method was then compared with the original method, as described below, in relation to the visual field defect severity. METHODS: The clinical records of 47 glaucomatous eyes with qualified photographs were obtained from a prior retrospective study. The reference point of the angle was set at the center of the optic disc center (COD group) and the central vessel trunk (COV group). Angle α was the angular width between the fovea and the proximity of RNFLD, while angle ß (+c) was the sum of the angular width(s) of localized RNFLD. The correlation between the visual field parameters and the angles of RNFLD in the above two groups were analyzed. RESULTS: There were significant differences in angle α (p = 0.001) and angle ß (+c) (p = 0.016) between the two groups. Angle ß (+c) showed significant correlation with MD (p = 0.012), PSD (p = 0.035), VFI (p = 0.042) and MD (p = 0.016), PSD (p = 0.035), VFI (p = 0.031) in the COD and COV group, respectively. No correlation was found between angle α and the presence of central scotoma in both groups. CONCLUSION: Our novel method was more convenient in a clinical setting and noninferior to the original method.

Tear Proteomics Study of Dry Eye Disease: Which Eye Do You Adopt as the Representative Eye for the Study?

Most studies about dry eye disease (DED) chose unilateral eye for investigation and drew conclusions based on monocular results, whereas most studies involving tear proteomics were based on the results of pooling tears from a group of DED patients. Patients with DED were consecutively enrolled for binocular clinical tests, tear biochemical markers of DED, and tear proteome. We found that bilateral eyes of DED patients may have similar but different ocular surface performance and tear proteome. Most ocular surface homeostatic markers and tear biomarkers were not significantly different in the bilateral eyes of DED subjects, and most clinical parameters and tear biomarkers were correlated significantly between bilateral eyes. However, discrepant binocular presentation in the markers of ocular surface homeostasis and the associations with tear proteins suggested that one eye's performance cannot represent that of the other eye or both eyes. Therefore, in studies for elucidating tear film homeostasis of DED, we may lose some important messages hidden in the fellow eye if we collected clinical and proteomic data only from a unilateral eye. For mechanistic studies, it is recommended that researchers collect tear samples from the eye with more severe DED under sensitive criteria for identifying the more severe eye and evaluating the tear biochemical and proteomic markers with binocular concordance drawn in prior binocular studies.

Comparison of fungal and bacterial keratitis between tropical and subtropical Taiwan: a prospective cohort study.

BACKGROUND: Fungal keratitis (FK) has been shown to be a climate-sensitive disease. The differentiation between FK from bacterial keratitis (BK) was difficult. The purpose of this study was to compare the bacteriology and mycology between tropical and subtropical Taiwan and to investigate the independent risk factors for identification of fungi from bacteria. METHODS: Two hundred ninety-seven patients with clinical suspected microbial keratitis were prospectively enrolled. A fungal to bacteria rate (FBR), the number of fungi divided by bacteria identified, was determined to estimate the prevalence of fungi and bacteria. Clinical presentation, profiles of microorganisms, and predisposing risk factors were determined. Univariate and multivariate logistic regression analysis were used to investigate the independent risk factors. RESULTS: A total of 82 fungi and 143 bacteria were laboratory confirmed. The identification rate of fungus was higher in tropical Taiwan (p = 0.010). Among the fungi and bacteria confirmed, the FBR was 0.29 (22.4% vs. 77.6%) in subtropical Taiwan, and 0.70 (41.3% vs. 58.7%) in tropical Taiwan. Samples obtained in tropical area (p = 0.019), ocular trauma (p = 0.019), and plant exposure (p = 0.003) were independent risk factors for identification of fungus from bacteria. The predominant fungus isolated from corneal scraping were Fusarium solani (25%) and Trichosporon faecale (25%) in subtropical Taiwan; in tropical Taiwan was Fusarium spp. (50%). CONCLUSIONS: The identification rate of fungus was higher in tropical Taiwan than subtropical Taiwan. Awareness of the local epidemiology is crucial for early diagnosis of fungal keratitis in tropical area.

Defective angles of localized retinal nerve fiber layer reflect the severity of visual field defect- a cross-sectional analysis.

BACKGROUND: In order to detect glaucomatous optic nerve damages early on and evaluate the severity of glaucoma, a previously developed analytic method based on photographic retinal nerve fiber layer (RNFL) angle defect was proposed. However, the correlation between these defective angles and the severity of visual field defect has not been verified. This study aimed to confirm the correlation described above. METHODS: We reviewed a total of 227 glaucomatous eyes (38 enrolled, 189 excluded) during an interval of 5 years. The angles of all eyes were measured on RNFL photograph, of which angle α is the angular width between the macula center and the proximity of RNFL defect, and angle ß (+c) is the sum of angular width(s) of localized RNFL defect. The severity of visual field defect was determined by mean deviation (MD), pattern standard deviation (PSD), and visual field index (VFI). Correlation analysis was performed on angle α and angle ß (+c) with the presence of central scotoma and visual field defect parameters, respectively. RESULTS: Angle ß (+c) showed significant correlation with MD (P = 0.007), PSD (P = 0.02), VFI (P = 0.03), and average RNFL thickness (P = 0.03). No correlation was found between angle α and the presence of central scotoma. CONCLUSIONS: In conclusion, measuring the angular width of localized RNFL defect is a viable method for determining the severity of visual field defect.

A Genomic Approach to Investigating Ocular Surface Microorganisms: Monitoring Core Microbiota on Eyelid Margin with a Dot hybridization Assay.

A sound ocular surface microbiota has been recognized as a part of ocular surface health following a growing body of evidence from next-generation sequencing technique and metagenomic analysis. However, even from the perspective of contemporary precision medicine, it is difficult to directly apply these new technologies to clinical practice. Therefore, we proposed a model based on dot hybridization assay (DHA) to bridge conventional culture with a metagenomic approach in investigating and monitoring ocular surface microbiota. Endophthalmitis, mostly caused by bacterial infection, is the most severe complication of many intraocular surgeries, such as cataract surgery. Hazardous microorganisms hiding and proliferating in the ocular surface microbiota not only increase the risk of endophthalmitis but also jeopardize the effectiveness of the preoperative aseptic procedure and postoperative topical antibiotics. The DHA model enables the simultaneous assessment of bacterial bioburden, detection of target pathogens and microorganisms, and surveillance of methicillin/oxacillin resistance gene mecA in the ocular surface microbiota. This assay revealed heavier bacterial bioburden in men, compatible with a higher risk of endophthalmitis in male patients who underwent cataract surgery. No occurrence of endophthalmitis for these patients was compatible with non-hazardous microorganisms identified by specific dots for target pathogens. Moreover, the mecA dot detected oxacillin-resistant strains, of which culture failed to isolate. Therefore, the DHA model could provide an alternative genomic approach to investigate and monitor ocular surface microorganisms in clinical practice nowadays.

Systematic Analysis of Transcriptomic Profile of the Effects of Low Dose Atropine Treatment on Scleral Fibroblasts using Next-Generation Sequencing and Bioinformatics.

This study has two novel findings: it is not only the first to deduct potential genes involved in scleral growth repression upon atropine instillation from a prevention point of view, but also the first to demonstrate that only slight changes in scleral gene expression were found after atropine treatment as side effects and safety reasons of the eye drops are of concern. The sclera determines the final ocular shape and size, constituting of scleral fibroblasts as the principal cell type and the major regulator of extracellular matrix. The aim of our study was to identify differentially expressed genes and microRNA regulations in atropine-treated scleral fibroblasts that are potentially involved in preventing the onset of excessive ocular growth using next-generation sequencing and bioinformatics approaches. Differentially expressed genes were functionally enriched in anti-remodeling effects, comprising of structural changes of extracellular matrix and metabolic pathways involving cell differentiation. Significant canonical pathways were correlated to inhibition of melatonin degradation, which was compatible with our clinical practice as atropine eye drops are instilled at night. Validation of the dysregulated genes with previous eye growth-related arrays and through microRNA-mRNA interaction predictions revealed the association of hsa-miR-2682-5p-KCNJ5 and hsa-miR-2682-5p-PRLR with scleral anti-remodeling and circadian rhythmicity. Our findings present new insights into understanding the anti-myopic effects of atropine, which may assist in prevention of myopia development.

Epidemiology and clinical features of viral anterior uveitis in southern Taiwan-diagnosis with polymerase chain reaction.

BACKGROUND: To report the epidemiology and clinical features of viral anterior uveitis in patients in southern Taiwan. METHODS: A retrospective, case series study. HLA-B27 negative anterior uveitis patients with increased intraocular pressure or corneal edema seen at Kaohsiung Chang Gung Memorial Hospital from January 1, 2007 to January 31, 2018 had their aqueous sent for polymerase chain reaction analysis. Their records were reviewed for demographic data, ocular findings, and laboratory results. RESULTS: In the aqueous samples obtained from 102 eligible eyes, 42 eyes were herpesviridae-positive, which included 9 with herpes simplex virus (8.8%), 5 with varicella-zoster virus (4.9%), 27 with cytomegalovirus (26.5%), and 1 with Epstein-Barr virus (1%). Herpesviridae-positive patients were more likely to be male, and have glaucoma. Glaucoma and pseudophakic eyes were significantly associated with CMV-positive eyes. CONCLUSION: PCR analysis of the anterior chamber fluid is important for the confirmation of the diagnosis of viral anterior uveitis. Cytomegalovirus anterior uveitis is not uncommon in patients in southern Taiwan, and it may follow an uneventful cataract extraction in immunocompetent patients.

An Omics Approach to Diagnosing or Investigating Fungal Keratitis.

Fungal keratitis (FK) is one of the most severe corneal infectious diseases. FK often leads to poor visual prognosis and thus requires accurate diagnosis. Conventional approaches, including clinical diagnoses, smears, and cultures, often fail to provide reliable diagnostic value. Omics approaches, such as those using genomic, metagenomic, and tear proteomic data sources, provide promising features for improving the diagnosis and monitoring the progression of FK. Genomic approaches are based mainly on detecting amplicons of ribosomal RNA genes, and internal transcribed spacers are gradually gaining popularity in clinical practices. A metagenomic approach based on 16S rRNA genes may help monitor the dynamic change of conjunctival microbiota associated with an FK event, whereas that based on shot-gun and 18S rRNA target enrichment sequencing could have the potential to diagnose FK using clinical samples. A tear proteomic approach may provide comprehensive information about ocular surface defense and injury during FK. Representative up- and down-regulated proteins during FK could also be used as biomarkers to determine the clinical course and develop a treatment strategy in different stages of FK. Consequently, a personalized tear proteomic approach will soon play a key role in FK management.

Tear Proteomics Approach to Monitoring Sjögren Syndrome or Dry Eye Disease.

Sjögren syndrome (SS) or dry eye disease (DED) is one of the most complicated ocular surface diseases. The goal of this study is to elucidate the relationship of the changes in clinical indices of tear film (TF) homeostasis with respect to tear components to allow for SS-DED monitoring and avoid stably controlled SS-DED patients from re-entering a vicious cycle. This prospective case-control study compared stable SS-DED patients with non-SS-DED control from several aspects, including clinical indices for TF homeostasis, 2 DED diagnostic biomarkers (MMP-9 and lactoferrin), and the proteome of flush tears. Compared with non-SS-DED controls, stably controlled SS-DED subjects had less tear secretion and higher ocular surface inflammation, a higher concentration ratio of tear MMP-9/lactoferrin, a more diverse tear proteome, and lower spectral intensities of lipocalin-1, lacritin, and prolactin-inducible protein among the abundant tear proteins. For stable SS-DED patients, the concentration ratio of tear MMP-9/lactoferrin and the corrected lipocalin-1 signal was positively correlated with ocular inflammation and TF stability, respectively. MMP-9 released from stressed ocular surface epithelium and lipocalin-1 secreted from the energetic lacrimal gland are two tear biomarkers responding well to TF homeostasis. The tear proteomics approach through flush tears is a promising method for monitoring SS-DED patients with a standardized sampling procedure and lactoferrin-corrected analysis.

The function and morphology of Meibomian glands in patients with thyroid eye disease: a preliminary study.

BACKGROUND: To investigate function and morphology of the meibomian gland (MG) in patients with thyroid eye disease (TED). METHODS: In this prospective case series study, patients with unilateral or bilateral TED were consecutively enrolled. The diagnosis of TED was based on the typical orbital findings and/or radiographic evidence. The disease activity of TED was classified according to the clinical activity score (CAS). Degrees of lagophthalmos and exophthalmos, blinking rates, and results of the Schirmer test 1 were also recorded. All patients completed the SPEED questionnaire and underwent MG assessment, including lipid layer thickness (LLT), MG dropout (MGd), and MG expression. RESULTS: In total 31 eyes from 17 patients with unilateral or bilateral TED were included. Patients were divided into inactive TED (CAS 0-1; 20 eyes from 11 patients) and active TED (CAS 2-3, 11 eyes from 6 patients) groups. MGd was significantly more severe in the active TED than the inactive TED group [Median (Inter-quartile region): 3.0 (2.0-3.0) vs. 2.0 (1.0-2.0) degree, P = 0.04]. However, patients with active TED had thicker LLT than those with inactive TED (90.0 [80.0-100.0] vs. 65.0 [47.8-82.5] nm, P = 0.02), and LLT was positively correlated with lagophthalmos (r = 0.37, P = 0.04). CONCLUSIONS: Patients with active TED had more severe MGd, but thicker LLT. Active TED may cause periglandular inflammation of MGs, leading to MGd, but compensatory secretion from residual MGs and lagophthalmos-induced forceful blinking might temporarily release more lipids over the tear film.

A dot hybridization assay for the diagnosis of bacterial keratitis.

PURPOSE: To evaluate a bacterial dot hybridization (BDH) assay for the diagnosis of bacterial keratitis (BK). METHODS: Sixty-one qualified corneal scrapings from 61 patients with suspected microbial keratitis were collected consecutively and prospectively. Among the 61 patients, 16 cases were BK and 45 cases were non-BK, including fungal keratitis, viral keratitis, parasitic keratitis, and non-microbial keratitis. Molecular diagnosis of BK in these corneal scrapes was performed using the BDH assay with three universal bacterial probes (PB1, PB2, and PB3) and three genus-specific probes (Aci, Klb, and Psu) to detect Acinetobacter, Klebsiella, and Pseudomonas, respectively. Signals were standardized after grayscale image transformation for objective validation using receiver operating characteristic (ROC) curves. RESULTS: The standardized intensities for the three universal probes differed statistically significantly between the BK group and the non-BK group. Based on the ROC curves, the sensitivities of PB1, PB2, and PB3 were 81.3%, 81.3%, and 93.8%, and the specificities were 71.1%, 88.9%, and 91.1%, respectively. The sensitivity and specificity of the Psu probe were 92% and 100%, respectively, while those of the Aci and Klb probes could not be estimated because there were no BK cases caused by Acinetobacter spp. or Klebsiella spp. CONCLUSIONS: The BDH assay is an effective molecular approach to improve the diagnosis of BK. Because the bias from bacterial contamination on the ocular surface can be minimized with signal standardization, the assay has the potential to be adopted for routine clinical practice.

A DNA dot hybridization model for molecular diagnosis of parasitic keratitis.

PURPOSE: Developing a DNA dot hybridization model for diagnosing parasitic keratitis. METHODS: Newly designed oligonucleotide probes for detecting Acanthamoeba and microsporidia were tested with target reference strains of Acanthamoeba (n = 20) and microsporidia (n = 3), and non-target microorganisms, including bacteria (n = 20) and fungi (n = 20). These probes, which had passed the preliminary tests, were then assembled as a parasite dot hybridization (PDH) model for assessing 33 clinical samples from patients with clinically suspected Acanthamoeba and microsporidia keratitis, including eight positives for Acanthamoeba, 13 positives for microsporidia, and 12 negatives for both pathogens. RESULTS: Two probes for detecting Acanthamoeba and two for detecting microsporidia passed the tests using target and non-target strains and then were assembled in the PDH model. For clinical samples, one Acanthamoeba-positive sample (proved with pathology) was falsely negative according to the PDH assay. The sensitivity and specificity of the PDH assay for diagnosing Acanthamoeba keratitis were 87.5% and 100%, respectively, while the sensitivity and specificity for diagnosing microsporidia keratitis were 100%. The infectious agent of all clinical samples of microsporidia keratitis was identified as Vittaforma corneae with DNA sequencing, while those of Acanthamoeba keratitis were caused by four species of Acanthamoeba, with Acanthamoeba castellanii found in four samples (50%, 4/8). CONCLUSIONS: The PDH model has the potential to be a molecular assay for diagnosing Acanthamoeba and microsporidia keratitis. However, a prospective clinical study might be needed before the model is adopted in routine clinical practice.

Bacterial Bioburden Decrease in Orthokeratology Lens Storage Cases After Forewarning: Assessment by the DNA Dot Hybridization Assay.

BACKGROUND: The aim of this study was to measure the changes in the bacterial bioburden in orthokeratology (OK) lens storage cases using the DNA dot hybridization assay (DHA) after forewarning patients about their bacterial contamination severity. METHODS: Thirty-one OK lens wearers were prospectively enrolled in this study. Dot hybridization assay was used for serial measurements of bacterial bioburden in OK storage cases after lenses had been soaked for approximately 6 hr. After the first assessment, the lens wearers were informed of the extent of case contamination and the possible risk of microbial keratitis (MK), and best practices for lens care and lens case hygiene were reviewed and reinforced. A second assessment by the same DHA method was performed after approximately 6 months. RESULTS: Two universal bacterial probes confirmed a significant decrease in bacterial bioburden at the second assessment (P<0.01 and P<0.001). Genus-specific probes showed significant reductions in Acinetobacter and Klebsiella (P=0.02 and P=0.01), but not in Pseudomonas (P=0.42). CONCLUSIONS: Making OK lens wearers aware of the bacterial bioburden in their lens cases resulted in improved quality of case care and reduced bioburden. Our results suggest that a strategy of bioburden assessment with forewarning could be a useful method to decrease the incidence of OK-related MK.

Isolates and antibiotic susceptibilities of endophthalmitis in postcataract surgery: a 12-year review of culture-proven cases.

The purpose of this study was to investigate the spectrum of organisms causing endophthalmitis after cataract surgery in a tertiary medical center in Taiwan and the antibiotic susceptibilities. This was a retrospective case series study. Patients with endophthalmitis after cataract surgery from January 2004 to July 2015 were reviewed. The outcome measures included the identification of isolates, antibiotic susceptibilities, and final visual outcomes. Twenty-one organisms were isolated from 19 cases. The most common organisms were Enterococcus in 38.1 %, especially Enterococcus faecalis, followed by Staphylococcus epidermidis in 28.6 % and Staphylococcus aureus in 9.5 %. All of the Gram-positive isolates tested were susceptible to vancomycin (100 %), and ceftazidime and amikacin were susceptible for Gram-negative organisms. The Gram-positive organisms remain to be the predominant cause of postoperative endophthalmitis, and Enterococcus species has had an increasing incidence. Vancomycin is still the most powerful antibiotic for Gram-positive organisms, while ceftazidime and amikacin are effective for Gram-negative bacteria.

PCR analysis for assessment of bacterial bioburden in orthokeratology lens cases.

PURPOSE: To develop a PCR gel analysis method for assessing the bacterial bioburden in orthokeratology contact lens (OK) case fluid determined by culture. METHODS: A prospective study with the participation of 41 OK wearers (20 girls, 21 boys) was performed. The mean OK-wearing experience was 3.5±1.9 years. PCR was used to assess the bacterial bioburden (colony-forming units per milliliter) of OK after removal and soaking in the storage case for 6 h. The signal intensity of the PCR bands was analyzed after grayscale image transformation. The difference (cPCR-d) and ratio (cPCR-r) between a PCR signal and its background were used as two standardized indices of PCR signals. The association between the two indices of the PCR signals and the bacterial bioburden determined by culture were analyzed with Pearson's correlation coefficient (r) and receiver operating characteristic (ROC) plots. RESULTS: At least one microbe was isolated from the OK lens case from 38 of the 41 subjects. Both cPCR-d and cPCR-r showed strong correlations with the bacterial bioburden (r>0.7, p<0.0001). ROC analysis enabled good determination of the cutoff values for the two PCR indices with acceptable sensitivity and specificity (78-89%) to assess the degree of bacterial contamination. CONCLUSIONS: The high microbial contamination rate of the OK lens cases revealed the general inappropriate lens care by OK wearers. PCR analysis provides an alternative and rapid method for assessing the bacterial bioburden of OK lens cases, and these results should serve as a warning to OK wearers to follow appropriate lens care procedures to prevent infection.

Microbial Bioburden of Orthokeratology Contact Lens Care System.

OBJECTIVE: To assess the bioburden in an orthokeratology contact lens (OK) care system (defined by microbial identification from OK case fluid) and to identify the risk factors causing high bioburden for pediatric OK wearers in southern Taiwan. METHODS: A prospective study for the investigation of bioburden in the OK care system was performed in a tertiary medical center in southern Taiwan. Microbial isolates from the case fluids soaking OKs were analyzed, and pathogenicity was determined. Age, gender, OK experiences, and contact lens care habits were considered the potential risk factors of microbial bioburden (colony-forming units per milliliter) for causal analysis. RESULTS: Forty-one OK wearers (20 female and 21 male subjects) participated in this study. The mean age was 12.7 years, and the mean OK-wearing experience was 3.5 years. A total of 86 microbial strains were isolated from 38 culture-positive specimens. Frequently reported pathogens in contact lens-related microbial keratitis were less common in the current study, but still present, including 4 strains (5%) of Serratia marcescens, 1 strain (1%) of Pseudomonas aeruginosa, and 1 strain (1%) of Staphylococcus aureus. Microbial bioburden of the OK care system was significantly higher (P<0.05) in male subjects. CONCLUSIONS: The contamination rate of the OK care system was high, and many isolated microorganisms had potential pathogenicity. Reinforcement of proper contact lens care and education should be mandatory for OK wearers, particularly for male subjects, to decrease the risk of high bioburden of the OK care system.