Therapeutic contact lenses for the treatment of corneal and ocular surface diseases: advances in extended and targeted drug delivery

The eye is one of the most important organs in the human body providing critical information on the environment. Many corneal diseases can lead to vision loss affecting the lives of people around the world. Ophthalmic drug delivery has always been a major challenge in the medical sciences. Since traditional methods are less efficient (∼ 5%) at delivering drugs to ocular tissues, contact lenses have generated growing interest in ocular drug delivery due to their potential to enhance drug bioavailability in ocular tissues. The main techniques used to achieve sustained release are discussed in this review, including soaking in drug solutions, incorporating drug into multilayered contact lenses, use of vitamin E barriers, molecular imprinting, nanoparticles, micelles and liposomes. The most clinically relevant results on different eye pathologies are presented. In addition, this review summarizes the benefits of contact lenses over eye drops, strategies for incorporating drugs into lenses to achieve sustained release, results of in vitro and in vivo studies, and the recent advances in the commercialization of therapeutic contact lenses for allergic conjunctivitis.

Reactivation of Herpes Zoster Keratitis Following Shingrix Vaccine

We present a case of herpes zoster keratitis reactivation shortly following the Shingrix vaccine. In our patient, reactivation of herpes zoster keratitis occurred a few weeks following the herpes zoster subunit (HZ/su) vaccine. The development of herpes zoster ophthalmicus following HZ/su is exceedingly rare, with only one prior reported case found in the literature. Reporting of this potential correlation is important in understanding the full risks of vaccines and can help elucidate the etiology of such responses.

Observational study of cenegermin for the treatment of limbal stem cell deficiency associated with neurotrophic keratopathy

Background:

Neurotrophic keratopathy (NK) and limbal stem cell deficiency (LSCD) have high morbidity and require aggressive management to prevent permanent vision loss. Cenegermin, a recombinant human nerve growth factor, was approved by the Federal Drug Administration in 2018 for the treatment of NK.

Objectives:

To determine the efficacy and safety of cenegermin in the treatment of LSCD associated with NK.

Design:

Prospective cohort study

Methods:

Patients diagnosed with LSCD and NK who had failed conventional treatment were enrolled in this prospective open-label study. Patients were treated with cenegermin for 8 weeks. The primary objective was to determine whether the area of abnormal epithelium decreased following treatment. Corneal sensation, visual acuity (VA), and LSCD severity were also evaluated.

Results:

Six eyes of 5 patients were included in the study. Cenegermin significantly improved the area of abnormal corneal epithelium in 5 of 6 eyes, measuring 73% of total corneal area at the initial visit and 48% at the final visit ( P = .036). Corneal sensation improved in all patients, Cochet–Bonnet aesthesiometry measured 14.7 and 26.7 mm at the initial and final visit, respectively ( P = .009). VA improved in 4 out of 6 eyes, with mean initial logMAR VA of 1.67 and final logMAR VA of 1.19 ( P = .045). Finally, LSCD grading improved using the Aravena scoring system; however, this difference was not statistically significant ( P = .14). One patient presented with an epithelial defect at baseline, which resolved following treatment. No patient withdrew from the study due to adverse effects.

Conclusions:

Cenegermin effectively improved the cornea epithelium, VA, and corneal sensation in patients with LSCD and NK who had failed prior treatment. Further studies are necessary to better understand the anatomical changes and to confirm our results with a larger randomized control trial.

Registration:

The study was registered at ClinicalTrials.gov with identifier NCT04552730 ( https://clinicaltrials.gov/ct2/show/NCT04552730 ).

Molecular mechanisms and treatments for ocular symblephara

There are currently no effective methods to prevent or durably treat ocular symblephara, the adhesions between the palpebral and bulbar conjunctiva. How symblephara form at the molecular level is largely unknown. We present here an overview of current clinical symblephara treatments and describe potential molecular mechanisms behind conjunctival adhesion formation that may inform future symblephara treatment and prevention options. Understanding how symblephara form at the molecular level will facilitate treatment development. Preventative therapies may be possible by targeting symblephara progenitor cells immediately after injuries, while novel therapeutics should be aimed at modulating TGF-β pathways and effector cells in conjunctival scarring to treat symblephara formation more effectively.

Drug delivery to the anterior segment of the eye: A review of current and future treatment strategies

Research in the development of ophthalmic drug formulations and innovative technologies over the past few decades has been directed at improving the penetration of medications delivered to the eye. Currently, approximately 90% of all ophthalmic drug formulations (e.g. liposomes, micelles) are applied as eye drops. The major challenge of topical eye drops is low bioavailability, need for frequent instillation due to the short half-life, poor drug solubility, and potential side effects. Recent research has been focused on improving topical drug delivery devices by increasing ocular residence time, overcoming physiological and anatomical barriers, and developing medical devices and drug formulations to increase the duration of action of the active drugs. Researchers have developed innovative technologies and formulations ranging from sub-micron to macroscopic size such as prodrugs, enhancers, mucus-penetrating particles (MPPs), therapeutic contact lenses, and collagen corneal shields. Another approach towards the development of effective topical drug delivery is embedding therapeutic formulations in microdevices designed for sustained release of the active drugs. The goal is to optimize the delivery of ophthalmic medications by achieving high drug concentration with prolonged duration of action that is convenient for patients to administer.

A Prospective, Randomized Trial of Povidone-Iodine 0.6% and Dexamethasone 0.1% Ophthalmic Suspension for Acute Bacterial Conjunctivitis

PURPOSE

To evaluate the efficacy and safety of a topical ophthalmic suspension combination of povidone-iodine 0.6% (PVP-I) and dexamethasone 0.1% (DEX) for infectious and inflammatory components of bacterial conjunctivitis.

DESIGN

Randomized, double-masked, multicenter, phase 3 clinical trial.

METHODS

Subjects of all ages (those <3 months had to be full-term) with a diagnosis of bacterial conjunctivitis were randomized 3:1:3 to either PVP-I/DEX, PVP-I alone, or placebo. The primary endpoint was clinical resolution in the study eye, and the key secondary efficacy endpoint was bacterial eradication, both at the day 5 visit. Adverse events (AEs) were documented at all visits.

RESULTS

Overall, 753 subjects were randomized (intent-to-treat [ITT] population; PVP-I/DEX [n = 324]; PVP-I [n = 108]; placebo [n = 321]); mean and standard deviation (SD) age was 44.3 (22.9) years, and most were female (61.2%) and white (78.1%). In all treatment groups, mean treatment compliance was >98%. The modified ITT population for the efficacy analysis comprised 526 subjects. In the study eye at the day 5 visit, clinical resolution was achieved by 50.5% (111/220) subjects in the PVP-I/DEX group vs 42.8% (95/222) in the placebo group (P = .127), and bacterial eradication was achieved by 43.3% (94/217) and 46.8% (102/218), respectively (P = .500). Treatment-emergent AEs were experienced by 32.8% (106/323), 39.8% (43/108), and 19.0% (61/321) of subjects in the safety population treated with PVP-I/DEX, PVP-I, and placebo, respectively (most mild in severity).

CONCLUSION

In this study, PVP-I/DEX did not demonstrate additional benefit in clinical efficacy compared with placebo in subjects with bacterial conjunctivitis.

Content validity of a novel patient-reported and observer-reported outcomes assessment to evaluate ocular symptoms associated with infectious conjunctivitis in both adult and pediatric populations

Background

Acute infectious conjunctivitis is a common condition most frequently caused by viruses or bacteria. Clinical outcome assessments have been used to assess signs and symptoms of bacterial and viral conjunctivitis, but have not been evaluated for content validity. We aimed to develop content-valid patient- (PRO) and observer-reported outcome (ObsRO) instruments to assess symptoms of ocular discomfort associated with viral or bacterial conjunctivitis in adult and pediatric patients.

Methods

Draft items were developed from a previous review of published studies from 2001 to 2015. Patients and caregivers of patients with a diagnosis of viral or bacterial conjunctivitis within the past 6 months were recruited. Concept elicitation with open-ended questions explored signs and symptoms, followed by cognitive interviewing to assess clarity and relevance of the draft items. Patients aged ≥8 years were interviewed for the PRO; parents/caregivers of children aged 1–10 years were interviewed for the ObsRO. Interviews were conducted in three rounds to allow changes. Concept saturation was documented using a saturation grid. Cognitive interview data were analyzed iteratively and focused on clarity, relevance and inconsistent interpretation of the instrument’s content.

Results

Overall, 23 patients or parents/caregivers participated (round 1, n = 10; round 2, n = 6; round 3, n = 7). Data saturation was reached by the 16th interview. The most frequent spontaneously reported signs/symptoms were: discharge, red/pink eyes, itchiness, swelling/puffiness, watery eyes, pain, burning and foreign body sensation. Itching, pain/burning/stinging and foreign body sensation were most commonly reported as the top three most bothersome symptoms. Interview results indicated that items on pain, itching and foreign body sensation for the PRO and pain or discomfort for the ObsRO were relevant to the patients’ experience of conjunctivitis and were clear and easy to understand.

Conclusions

PRO and ObsRO items were found to be clear, relevant and appropriate in assessing key viral and bacterial conjunctivitis symptoms in adult and pediatric patients.

Oral miltefosine for refractory Acanthamoeba keratitis

Purpose

To report the first case of Acanthamoeba keratitis treated with oral miltefosine in the United States.

Observations

A 17-year-old female with a history of orthokeratology contact lens wear presented after five months of left eye pain, redness, and photophobia. She was previously treated with antivirals and topical corticosteroids for presumed herpetic disease. She was found to have a large central ring infiltrate and corneal cultures were positive for Acanthamoeba. The infection progressed despite hourly PHMB 0.02% and chlorhexidine 0.02%, and oral vorizonazole. The patient was started on oral miltefosine 50 mg 3 times per day. Following one week of treatment, repeat cultures were positive for Acanthamoeba and therefore, the concentration of chlorhexidine was increased from 0.02% to 0.06% and PHMB was changed to propamidine isetionate (Brolene 0.1%). There was definite clinical improvement after five weeks of treatment with oral miltefosine, topical chlorhexidine 0.06% and propamidine isetionate 0.1%.

Conclusions and importance

Acanthamoeba keratitis is a challenging entity to treat and often associated with a poor prognosis. Oral miltefosine may offer additional therapeutic benefit in cases of refractory Acanthamoeba keratitis.

Chronic Electrical Stimulation for Tear Secretion: Lacrimal vs. anterior ethmoid nerve

PURPOSE

To evaluate and compare the effect of lacrimal nerve stimulation (LNS) and anterior ethmoid nerve stimulation (AENS) on aqueous tear secretion, and tissue condition following chronic implantation.

METHODS

A neurostimulator was implanted in rabbits adjacent to the (1) lacrimal nerve, and (2) anterior ethmoid nerve. Tear volume was measured with Schirmer test strips after stimulation (2.3-2.8 mA pulses at 30 Hz for 3-5 min), and scores were compared to sham stimulation. Lacrimal gland and nasal septal tissue were evaluated histologically after chronic stimulation (2 weeks-7 months).

RESULTS

LNS increases tear volume by 32% above sham (p < 0.05, n = 5), compared with 133% for AENS (p ≤ 0.01, n = 6). AENS also significantly increases tear secretion in the fellow, non-stimulated eye (p ≤ 0.01, n = 6), as expected from the tearing reflex pathway. Histologically, chronic LNS is well tolerated by surrounding tissues while chronic AENS results in nasal mucosal fibrosis and implant extrusion within 3 weeks.

CONCLUSIONS

AENS is significantly more effective than LNS at enhancing aqueous tear secretion, including the fellow eye. The lacrimal implant is well tolerated, while the nasal implant requires further design optimization to improve tolerability.

Enhanced Tearing by Electrical Stimulation of the Anterior Ethmoid Nerve

Purpose

Electrical neurostimulation enhances tear secretion, and can be applied to treatment of dry eye disease. Using a chronic implant, we evaluate the effects of stimulating the anterior ethmoid nerve on the aqueous, lipid, and protein content of secreted tears.

Methods

Neurostimulators were implanted beneath the nasal mucosa in 13 New Zealand white rabbits. Stimulations (2.3–2.8 mA pulses of 75–875 μs in duration repeated at 30–100 Hz for 3 minutes) were performed daily, for 3 weeks to measure changes in tear volume (Schirmer test), osmolarity (TearLab osmometer), lipid (Oil-Red-O staining), and protein (BCA assay, mass spectrometry).

Results

Stimulation of the anterior ethmoid nerve in the frequency range of 30 to 90 Hz increased tear volume by 92% to 133% (P ≤ 0.01). Modulating the treatment with 50% duty cycle (3 seconds of stimulation repeated every 6 seconds) increased tear secretion an additional 23% above continuous stimulation (P ≤ 0.01). Tear secretion returned to baseline levels within 7 minutes after stimulation ended. Tear film osmolarity decreased by 7 mOsmol/L, tear lipid increased by 24% to 36% and protein concentration increased by 48% (P ≤ 0.05). Relative abundance of the lacrimal gland proteins remained the same, while several serum and corneal proteins decreased with stimulation (P ≤ 0.05).

Conclusions

Electrical stimulation of the anterior ethmoid nerve increased aqueous tear volume, reduced tear osmolarity, added lipid, and increased the concentration of normal tear proteins. Human studies with an intranasal stimulator should verify these effects in patients with aqueous- and lipid-deficient forms of dry eye disease.

Biocompatibility of poly(ethylene glycol) and poly(acrylic acid) interpenetrating network hydrogel by intrastromal implantation in rabbit cornea

We evaluated the biocompatibility of a poly(ethylene glycol) and poly(acrylic acid) (PEG/PAA) interpenetrating network hydrogel designed for artificial cornea in a rabbit model. PEG/PAA hydrogel measuring 6 mm in diameter was implanted in the corneal stroma of twelve rabbits. Stromal flaps were created with a microkeratome. Randomly, six rabbits were assigned to bear the implant for 2 months, two rabbits for 6 months, two rabbits for 9 months, one rabbit for 12 months, and one rabbit for 16 months. Rabbits were evaluated monthly. After the assigned period, eyes were enucleated, and corneas were processed for histology and immunohistochemistry. There were clear corneas in three of six rabbits that had implantation of hydrogel for 2 months. In the six rabbits with implant for 6 months or longer, the corneas remained clear in four. There was a high rate of epithelial defect and corneal thinning in these six rabbits. One planned 9-month rabbit developed extrusion of implant at 4 months. The cornea remained clear in the 16-month rabbit but histology revealed epithelial in-growth. Intrastromal implantation of PEG/PAA resulted in a high rate of long-term complications.

Interpenetrating polymer network hydrogel scaffolds for artificial cornea periphery

Three-dimensional scaffolds based on inverted colloidal crystals (ICCs) were fabricated from sequentially polymerized interpenetrating polymer network (IPN) hydrogels of poly(ethyleneglycol) and poly(acrylic acid). This high-strength, high-water-content IPN hydrogel may be suitable for use in an artificial cornea application. Development of a highly porous, biointegrable region at the periphery of the artificial cornea device is critical to long-term retention of the implant. The ICC fabrication technique produced scaffolds with well-controlled, tunable pore and channel dimensions. When surface functionalized with extracellular matrix proteins, corneal fibroblasts were successfully cultured on IPN hydrogel scaffolds, demonstrating the feasibility of these gels as materials for the artificial cornea porous periphery. Porous hydrogels with and without cells were visualized non-invasively in the hydrated state using variable-pressure scanning electron microscopy.

Prevention and treatment of injection-related endophthalmitis

BACKGROUND

Intravitreal injections are the fastest growing cause of endophthalmitis and can result in severe vision loss. The prevention, diagnosis and management of such infections remain unclear and at times controversial.

METHODS

We searched Pubmed for keywords "prophylaxis," "endophthalmitis," "intravitreal injection." We focused on studies published in the last 2 years as well as other recent studies with particular attention to data on the incidence, microbiology, prevention, and treatment of injection-related endophthalmitis.

RESULTS

Over 20 relevant studies were found. With povidone-iodine preparation, the per-injection endophthalmitis rate is low at about 0.03%. Antibiotics do not appear to be beneficial for prevention of post-injection endophthalmitis. The best timing of vitrectomy is unclear.

CONCLUSIONS

Antibiotic prophylaxis is probably not needed when giving intravitreal injections. More data is needed to help determine the proper treatment for post-injection endophthalmitis.

In vivo biocompatibility of two PEG/PAA interpenetrating polymer networks as corneal inlays following deep stromal pocket implantation

This study compared the effects of implanting two interpenetrating polymer networks (IPNs) into rabbit corneas. The first (Implant 1) was based on PEG-diacrylate, the second (Implant 2) was based on PEG-diacrylamide. There were inserted into deep stromal pockets created using a manual surgical technique for either 3 or 6 months. The implanted corneas were compared with normal and sham-operated corneas through slit lamp observation, anterior segment optical coherence tomography, in vivo confocal scanning and histological examination. Corneas with Implant 1 (based on PEG-diacrylate) developed diffuse haze, ulcers and opacities within 3 months, while corneas with Implant 2 (based on PEG-diacrylamide) remained clear at 6 months. They also exhibited normal numbers of epithelial cell layers, without any immune cell infiltration, inflammation, oedema or neovascularisation at post-operative 6 month. Morphological studies showed transient epithelial layer thinning over the hydrogel inserted area and elevated keratocyte activity at 3 months; however, the epithelium thickness and keratocyte morphology were improved at 6 months. Implant 2 exhibited superior in vivo biocompatibility and higher optical clarity than Implant 1. PEG-diacrylamide-based IPN hydrogel is therefore a potential candidate for corneal inlays to correct refractive error.

Diffusion of protein through the human cornea

AIMS

To determine the rate of diffusion of myoglobin and bovine serum albumin (BSA) through the human cornea. These small proteins have hydrodynamic diameters of approximately 4.4 and 7.2 nm, and molecular weights of 16.7 and 66 kDa, for myoglobin and BSA, respectively.

METHODS

Diffusion coefficients were measured using a diffusion chamber where the protein of interest and balanced salt solution were in different chambers separated by an ex vivo human cornea. Protein concentrations in the balanced salt solution chamber were measured over time. Diffusion coefficients were calculated using equations derived from Fick's law and conservation of mass in a closed system.

RESULTS

Our experiments demonstrate that the diffusion coefficient of myoglobin is 5.5 ± 0.9 × 10(-8) cm(2)/s (n = 8; SD = 1.3 × 10(-8) cm(2)/s; 95% CI: 4.6 × 10(-8) to 6.4 × 10(-8) cm(2)/s) and the diffusion coefficient of BSA is 3.1 ± 1.0 × 10(-8) cm(2)/s (n = 8; SD = 1.4 × 10(-8) cm(2)/s; 95% CI: 2.1 × 10(-8) to 4.1 × 10(-8) cm(2)/s).

CONCLUSIONS

Our study suggests that molecules as large as 7.2 nm may be able to passively diffuse through the human cornea. With applications in pharmacotherapy and the development of an artificial cornea, further experiments are warranted to fully understand the limits of human corneal diffusion and its clinical relevance.

Toward the development of an artificial cornea: improved stability of interpenetrating polymer networks

A novel interpenetrating network (IPN) based on poly(ethylene glycol) (PEG) and poly(acrylic acid) was developed and its use as an artificial cornea was evaluated in vivo. The in vivo results of a first set of corneal inlays based on PEG-diacrylate precursor showed inflammation of the treated eyes and haze in the corneas. The insufficient biocompatibility could be correlated to poor long-term stability of the implant caused by hydrolytic degradation over time. Adapting the hydrogel chemistry by replacing hydrolysable acrylate functionalities with stable acrylamide functionalities was shown to increase the long-term stability of the resulting IPNs under hydrolytic conditions. This new set of hydrogel implants now shows increased biocompatibility in vivo. Rabbits with corneal inlay implants are healthy and have clear cornea and non-inflamed eyes for up to 6 months after implantation.

Morphology of Photopolymerized End-linked Poly(ethylene glycol) Hydrogels by Small Angle X-ray Scattering

Due to the biocompatibility of poly(ethylene glycol) (PEG), PEG-based hydrogels have attracted considerable interest for use as biomaterials in tissue engineering applications. In this work, we show that PEG-based hydrogels prepared by photopolymerization of PEG macromonomers functionalized with either acrylate or acrylamide end-groups generate networks with crosslink junctions of high functionality. Although the crosslink functionality is not well controlled, the resultant networks are sufficiently well ordered to generate a distinct correlation peak in the small angle x-ray scattering (SAXS) related to the distance between crosslink junctions within the PEG network. The crosslink spacing is a useful probe of the PEG chain conformation within the hydrogel and ranges from approximately 6 to 16 nm, dependent upon both the volume fraction of polymer and the molecular weight of the PEG macromonomers. The presence of a peak in the scattering of photopolymerized PEG networks is also correlated with an enhanced compressive modulus in comparison to PEG networks reported in the literature with much lower crosslink functionality that exhibit no scattering peak. This comparison demonstrates that the method used to link together PEG macromonomers has a critical impact on both the nanoscale structure and the macroscopic properties of the resultant hydrogel network.

Prospective study of risk factors for conjunctival bacterial contamination in patients undergoing intraocular surgery

PURPOSE

To determine whether a patient's age, gender, local or systemic risk factors affect the rate of preoperative bacterial contamination.

METHODS

Consecutive 1,474 patients undergoing intraocular surgery were enrolled in this prospective masked study. Past medical history was noted and examinations were performed. The patients were divided into four groups: a control group (without local or systemic risk factors), those with local risk factors (chronic use of topical medications, contact lens wear, blepharitis, chronic eyelid or conjunctival inflammation), those with systemic risk factors (immunosuppression, diabetes, autoimmune conditions, and asthma), and those with both. Conjunctival cultures were obtained before surgery.

RESULTS

Among the 1,474 patients, 914 bacteria were isolated from 214 (14.9%) patients. Advanced age was associated with a higher rate of positive conjunctival cultures (p<0.005). No statistical difference was found with regard to gender (p=0.7173). Among the 282 patients in the control group, 14 (5%) had a positive conjunctival culture. Compared to the control group, positive conjunctival cultures were found in 118 out of 503 patients (23.5%) with local risk factors (p<0.0001), 65 out of 545 patients (11.9%) with systemic risk factors (p=0.0019), and 22 out of 144 (15.3%) with both (p=0.0006). Two patients developed postoperative endophthalmitis (0.14%), one with both local risk and systemic factors and the other with a systemic risk factor.

CONCLUSIONS

Patients with local or systemic risk factors or advanced age were found to have a higher rate of bacterial conjunctival contamination before intraocular surgery.

One-day application of topical moxifloxacin 0.5% to select for fluoroquinolone-resistant coagulase-negative Staphylococcus

PURPOSE

To compare selection for fluoroquinolone-resistant bacteria between 1-day and 3-day application of topical moxifloxacin 0.5%.

SETTING

Department of Ophthalmology, Stanford University, Stanford, California, USA.

METHODS

After investigative review board approval, patients scheduled for ocular surgery were randomized to receive topical moxifloxacin 0.5% drops 4 times a day for 1 day or 3 days preoperatively. Conjunctival cultures were obtained at baseline and after antibiotic application. Bacteria were identified and tested for resistance to a battery of antibiotic agents using the Kirby-Bauer disk-diffusion method. The differences in resistance distributions for the most commonly isolated bacteria between baseline (T0) and after antibiotic administration (T1) were compared between the 2 treatment groups.

RESULTS

Coagulase-negative Staphylococcus (CNS) were the most common bacteria isolated at T0 and T1. At T0, the proportion of CNS isolated in the 1-day group (n = 63) that was resistant to fluoroquinolones ranged from 4% to 22% depending on the antibiotic agent tested. After 1-day treatment with moxifloxacin, the percentage of resistant bacteria increased significantly (range 13% to 67%) for all fluoroquinolones except gatifloxacin (P<.05). Resistance to gentamicin and tobramycin also increased significantly. However, patients treated for 3 days (n = 57) showed no differences in bacterial resistance rates to any antibiotic agent tested.

CONCLUSION

Prophylactic topical moxifloxacin 0.5% treatment starting 1 day before ocular surgery resulted in a significant increase in fluoroquinolone-resistant bacteria, while a 3-day antibiotic regimen did not select for resistant organisms.

Prospective randomized comparison of 1-day and 3-day application of topical 0.5% moxifloxacin in eliminating preoperative conjunctival bacteria

PURPOSE

Compare the efficacy of a 1-day versus 3-day application of topical 0.5% moxifloxacin in reducing preoperative conjunctival bacteria.

METHODS

Following IRB approval, patients (n = 144) scheduled for ocular surgery between 2004 and 2005 were recruited and randomized to receive topical 0.5% moxifloxacin drops four times a day for either 1 day (n = 63) or 3 days (n = 57) prior to surgery. Conjunctival cultures were obtained at baseline (T0), after application of antibiotic (T1), following povidone-iodine and additional antibiotic applications immediately before surgery (T2), and after surgery (T3). Cultures were inoculated onto blood and chocolate agar plates and in thioglycolate broth, and then incubated at 37 degrees C for 10 days. Bacterial growth were isolated, identified, quantified, and compared.

RESULTS

There were similar (P = 0.8435) rates of patients with positive thioglycolate cultures between the 1-day (79.37%) and 3-day groups (82.46%) at T0. At T1, T2, and T3, the number of eyes with positive cultures were again similar (1 day, 3 days, P value [T1: 34.9%, 35.1%, P = 0.8631; T2: 14.3%, 7%, P = 0.3245; T3: 7.9%, 3.5%, P = 0.5199]). No significant differences were found between the colony-forming units (CFU) of bacteria on solid agar media in 1-day and 3-day groups at any of the time points studied (P values: 0.1-0.8). Coagulase-negative Staphylococcus was the most commonly isolated (73.3% at baseline).

CONCLUSIONS

In patients undergoing intraocular anterior segment surgery, 1-day and 3-day applications of topical 0.5% moxifloxacin appear to have similar efficacy in reducing perioperative conjunctival bacteria.

Bioactive interpenetrating polymer network hydrogels that support corneal epithelial wound healing

The development and characterization of collagen-coupled poly(ethylene glycol)/poly(acrylic acid) (PEG/PAA) interpenetrating polymer network hydrogels is described. Quantitative amino acid analysis and FITC-labeling of collagen were used to determine the amount and distribution of collagen on the surface of the hydrogels. The bioactivity of the coupled collagen was detected by a conformation-specific antibody and was found to vary with the concentration of collagen reacted to the photochemically functionalized hydrogel surfaces. A wound healing assay based on an organ culture model demonstrated that this bioactive surface supports epithelial wound closure over the hydrogel but at a decreased rate relative to sham wounds. Implantation of the hydrogel into the corneas of live rabbits demonstrated that epithelial cell migration is supported by the material, although the rate of migration and morphology of the epithelium were not normal. The results from the study will be used as a guide toward the optimization of bioactive hydrogels with promise in corneal implant applications such as a corneal onlay and an artificial cornea.

A prospective randomized evaluation of topical gatifloxacin on conjunctival flora in patients undergoing intravitreal injections

PURPOSE

We sought to assess the efficacy of 3-day topical gatifloxacin use in combination with povidone-iodine (PVI) versus PVI alone in eliminating conjunctival bacterial flora in patients scheduled to undergo intravitreal (IVT) injection.

DESIGN

Prospective, randomized single-blind clinical trial.

PARTICIPANTS

We included 129 patients scheduled to undergo 273 IVT injections at California Vitreoretinal Center at Stanford University.

METHODS

Study patients were randomized to self-administration of gatifloxacin drops for 3 days before injection, or no pretreatment antibiotics. Cultures were collected from the bulbar conjunctiva at the injection site and at the corresponding location in the fellow eye before PVI preparation. After topical PVI treatment and immediately before injection, a third culture was obtained at the injection site. Additionally, the injection needle was also cultured after the procedure.

MAIN OUTCOME MEASURES

Incidence of positive bacterial samples collected from injection site conjunctiva and injection needles.

RESULTS

Three-day gatifloxacin use resulted in a significantly lower rate of SeptiChek (Becton Dickinson, Franklin Lakes, NJ) positive cultures compared with untreated controls (21% vs 48% respectively, P = 0.005). After topical PVI, the rate of positive bacterial cultures in gatifloxacin-treated and control eyes were similar (8% and 4%, respectively; P = 0.324).

CONCLUSIONS

Although 3-day topical gatifloxacin use is effective in reducing the frequency of conjunctival bacterial growth relative to untreated eyes, antibiotic use confers no additional benefit in combination with PVI than eyes receiving PVI alone. This supports that topical PVI is an effective preinjection monotherapy for infection prophylaxis in the setting of IVT injections.

A prospective study determining the efficacy of topical 0.5% levofloxacin on bacterial flora of patients with chronic blepharoconjunctivitis

BACKGROUND

To determine the efficacy of conjunctival bacterial eradication following a 1-day, 3-day and 7-day application of topical 0.5% levofloxacin, with and without eyelid scrub, in patients with chronic blepharoconjunctivitis (CBC).

METHODS

Patients with CBC (n = 60) were prospectively randomized to three groups (n = 20 in each group): no antibiotic treatment, topical levofloxacin four times per day in both eyes, and eyelid scrub in addition to topical levovofloxacin four times a day in both eyes. Patients without CBC (n = 40) were enrolled as the negative control group. Cultures of the conjunctiva were obtained from both eyes at baseline, 1 day, 3 days, and 7 days following treatment.

RESULTS

The most common bacteria isolated for all groups at baseline were coagulase-negative Staphylococcus. Eight patients did not complete the study. The remaining 52 patients with CBC had a significantly higher rate of positive thioglycolate broth cultures (94%) compared to a 58% positive culture rate in patient without CBC (P < 0.0001). Treatment with at least 3 days of topical antibiotic in patient with CBC resulted in a significant reduction (P < 0.05) in the number of thioglycolate positive cultures (<or= 60%) compared to non-treated eyes (>or= 88%). Following a minimum of a 1-day application of antibiotic, the median colony-forming unit was 0-1 compared to 3-8 for eyes without antibiotic treatment (P < 0.05). Scrubbing of the eyelids did not provide further benefit compared to antibiotic treatment alone.

CONCLUSIONS

CBC eyes have a significantly higher number of positive cultures than eyes without CBC. The application of topical 0.5% levofloxacin for at least 3 days provided a significant reduction in the number of positive cultures as well as the number of bacteria harbored on the conjunctival surface.

Prospective comparison of topical moxifloxacin in eliminating conjunctival bacterial flora following a one-day or one-hour application

PURPOSE

The aim of this study was to compare the efficacy of a 1-hour(h) versus 1-day application of topical moxifloxacin in eliminating conjunctival bacterial flora.

METHODS

In this prospective, nonrandomized, controlled trial, the surgical eyes of 60 patients scheduled for intraocular surgery received topical moxifloxacin four times a day, starting 1 day prior to surgery and three additional applications at 5-minute intervals 1 h before surgery. The nonsurgical eye of each patient only received three applications of the same antibiotic at 5-minute intervals 1 h before surgery. Conjunctival cultures were obtained at baseline and after antibiotic application.

RESULTS

Prior to antibiotic application, 80% of surgical eyes and 70% of nonsurgical eyes had positive cultures. Following the 1-day application, significantly fewer eyes (40%) had positive cultures (P < 0.0001), with a further reduction to 32% with three additional doses 1 h prior to surgery. In the nonsurgical eye, the decrease in the percentage of positive cultures, from 55% to 53% following the three applications 1 h prior to surgery, was not significant (P > 0.9999). The 1-day application was associated with significantly fewer positive cultures, compared to the 1-h group (P = 0.0267).

CONCLUSIONS

The one-day application of moxifloxacin resulted in significantly fewer positive conjunctival cultures, compared with a 1-h application.

Bacterial contamination of ocular surface and needles in patients undergoing intravitreal injections

PURPOSE

To evaluate potential sources of bacterial contamination during intravitreal (IVT) injection procedures.

METHODS

Patients scheduled for IVT injection were asked to enroll in the study at the California Vitreoretinal Center (Menlo Park, CA) and the Vantage Eye Center (Salinas, CA) between October 2004 and April 2005. A total of 104 patients participated in the study, with a total of 118 IVT injection procedures performed on 107 eyes. Standard microbiological techniques were used to culture, identify, and quantify bacterial contamination of injection needles and the bulbar conjunctiva at the injection site in patients undergoing IVT injections. The main outcomes measured were type and quantity of bacterial isolates.

RESULTS

Two (2%) of 114 needles collected were contaminated with bacteria. The prevalence of bacterial contamination of the injection site on the bulbar conjunctiva was 43% before prophylaxis on the day of the injection with topical antibiotics and povidone-iodine, with a statistically significant reduction to 13% after prophylaxis (P < 0.0001). Coagulase-negative Staphylococcus, the most common bacterium isolated from the ocular surface, was isolated from both culture-positive needles.

CONCLUSIONS

IVT injection needles became contaminated with bacteria during the injection procedure. Although the contamination rate was low, this supports a mechanism of postinjection endophthalmitis in which there is direct inoculation of ocular surface flora into the vitreous cavity by the injection needle.

Development of hydrogel-based keratoprostheses: a materials perspective

Research and development of artificial corneas (keratoprostheses) in recent years have evolved from the use of rigid hydrophobic materials such as plastics and rubbers to hydrophilic, water-swollen hydrogels engineered to support not only peripheral tissue integration but also glucose diffusion and surface epithelialization. The advent of the AlphaCor core-and-skirt hydrogel keratoprosthesis has paved the way for a host of new approaches based on hydrogels and other soft materials that encompass a variety of materials preparation strategies, from synthetic homopolymers and copolymers to collagen-based bio-copolymers and, finally, interpenetrating polymer networks. Each approach represents a unique strategy toward the same goal: to develop a new hydrogel that mimics the important properties of natural donor corneas. We provide a critical review of these approaches from a materials perspective and discuss recent experimental results. While formidable technical hurdles still need to be overcome, the rapid progress that has been made by investigators with these approaches is indicative that a synthetic donor cornea capable of surface epithelialization is now closer to becoming a clinical reality.

Glucose-permeable interpenetrating polymer network hydrogels for corneal implant applications: a pilot study

Epithelialization of a keratoprosthesis requires that the implant material be sufficiently permeable to glucose. We have developed a poly(ethylene glycol)/poly(acrylic acid) (PEG/PAA) interpenetrating polymer network (IPN) hydrogel that can provide adequate passage of glucose from the aqueous humor to the epithelium in vivo. A series of PEG/PAA IPNs with varying PEG macromonomer molecular weights were synthesized and evaluated through swelling studies to determine their water content and diffusion experiments to assess their permeability to glucose. One of the PEG/PAA hydrogels prepared in this study had a glucose diffusion coefficient nearly identical to that of the human cornea (approximately 2.5 x 10(-6) cm(2)/sec). When implanted intrastromally in rabbit corneas, this hydrogel was retained and well-tolerated in 9 out of 10 cases for a period of 14 days. The retained hydrogels stayed optically clear and the epithelium remained intact and multilayered, indicating that the material facilitated glucose transport from the aqueous humor to the anterior part of the eye. The results from these experiments indicate that PEG/PAA hydrogels are promising candidates for corneal implant applications such as keratoprostheses and intracorneal lenses, and that the PEG/PAA IPN system in general is useful for creating permeable substrates for ophthalmic and other biomedical applications.

Design and fabrication of an artificial cornea based on a photolithographically patterned hydrogel construct

We describe the design and fabrication of an artificial cornea based on a photolithographically patterned hydrogel construct, and demonstrate the adhesion of corneal epithelial and fibroblast cells to its central and peripheral components, respectively. The design consists of a central "core" optical component and a peripheral tissue-integrable "skirt." The core is composed of a poly(ethylene glycol)/poly(acrylic acid) (PEG/PAA) double-network with high strength, high water content, and collagen type I tethered to its surface. Interpenetrating the periphery of the core is a microperforated, but resilient poly(hydroxyethyl acrylate) (PHEA) hydrogel skirt that is also surface-modified with collagen type I. The well-defined microperforations in the peripheral component were created by photolithography using a mask with radially arranged chrome discs. Surface modification of both the core and skirt elements was accomplished through the use of a photoreactive, heterobifunctional crosslinker. Primary corneal epithelial cells were cultured onto modified and unmodified PEG/PAA hydrogels to evaluate whether the central optic material could support epithelialization. Primary corneal fibroblasts were seeded onto the PHEA hydrogels to evaluate whether the peripheral skirt material could support the adhesion of corneal stromal cells. Cell growth in both cases was shown to be contingent on the covalent tethering of collagen. Successful demonstration of cell growth on the two engineered components was followed by fabrication of core-skirt constructs in which the central optic and peripheral skirt were synthesized in sequence and joined by an interpenetrating diffusion zone.

Progress in the development of interpenetrating polymer network hydrogels

Interpenetrating polymer networks (IPNs) have been the subject of extensive study since their advent in the 1960s. Hydrogel IPN systems have garnered significant attention in the last two decades due to their usefulness in biomedical applications. Of particular interest are the mechanical enhancements observed in "double network" IPN systems which exhibit nonlinear increases in fracture properties despite being composed of otherwise weak polymers. We have built upon pioneering work in this field as well as in responsive IPN systems to develop an IPN system based on end-linked poly-(ethylene glycol) (PEG) and loosely crosslinked poly(acrylic acid) (PAA) with hydrogen bond-reinforced strain-hardening behavior in water and high initial Young's moduli under physiologic buffer conditions through osmotically induced pre-stress. Uniaxial tensile tests and equilibrium swelling measurements were used to study PEG/PAA IPN hydrogels having second networks prepared with varying crosslinking and photoinitiator content, pH, solids content, and comonomers. Studies involving the addition of non-ionic comonomers and neutralization of the second network showed that template polymerization appears to be important in the formation of mechanically enhanced IPNs.

A prospective randomized study to determine the efficacy of preoperative topical levofloxacin in reducing conjunctival bacterial flora

PURPOSE

To compare the efficacy of topical levofloxacin in combination with povidone-iodine irrigation vs povidone-iodine (PVI) alone in reducing conjunctival bacteria.

DESIGN

Prospective, randomized, controlled trial.

METHODS

One hundred and forty eyes of 140 patients scheduled to undergo intraocular surgery eyes were randomized to either group 1 or 2 (70 each). Whereas group 1 eyes had no prophylactic antibiotic, eyes in group 2 received topical treatment with one drop of 0.5% levofloxacin four times on the day before surgery. Both groups underwent irrigation of the fornices with 1% PVI. Conjunctival swabs were inoculated on solid and broth culture media to determine bacterial growth.

RESULTS

Of 132 eyes evaluated, baseline culture analysis in thioglycolate demonstrated positive culture results in 55 (84.6%) of 65 eyes from group 1, similar to 55 (82.1%) of 67 eyes in group 2 (P = .697). Before surgery, 57 (87.7%) of 65 eyes in group 1 had positive culture results, compared with 50 (74.6%) of 67 eyes in group 2 (P = .055). After irrigation with PVI, 20 (30.8 %) of 65 eyes in group 1 had positive culture results, compared with only eight (11.9%) of 67 eyes in group 2 (P = .008). After surgery, 15 (23.1%) of 65 eyes in group 1 and six (9.0%) of 67 eyes in group 2 had positive culture results (P = .027).

CONCLUSIONS

Our study shows an enhanced effect of using topical levofloxacin in combination with PVI irrigation to reduce conjunctival bacteria in patients undergoing intraocular surgery.

Aspergillus fumigatus keratitis following laser in situ keratomileusis

A 31-year-old woman developed pain, decreased vision, and a corneal flap infiltrate 4 days following laser in situ keratomileusis (LASIK). Treatment with topical antibiotic agents did not improve the symptoms. Approximately 2 weeks after surgery, the patient was referred to Stanford University, with 20/400 visual acuity in the left eye and a stromal infiltrate posterior to the flap. Cultures demonstrated Aspergillus fumigatus sensitive to voriconazole. The corneal ulcer progressed despite aggressive antifungal treatment, requiring amputation of the corneal flap and daily debridement. The infiltrate resolved in response to topical voriconazole, natamycin, and oral voriconazole. Aspergillus fumigatus keratitis is a rare but serious complication of LASIK surgery. The infection was successfully treated with flap amputation and daily debridement in addition to antifungal therapy.

Prospective randomized comparison of 1-day versus 3-day application of topical levofloxacin in eliminating conjunctival flora

PURPOSE

To compare efficacy of a 1-day versus 3-day application of topical levofloxacin in reducing ocular surface bacteria.

METHODS

In this prospective randomized controlled trial, 100 volunteer patients (50 per group) were assigned to receive topical 0.5% levofloxacin four times daily for 1 day or 3 days. Conjunctival cultures were obtained prior to (T0) and after the application of antibiotics (T1). Additionally, all patients received topical levofloxacin at 5-minute intervals for three applications (T2), followed by two drops of topical 5% povidone-iodine (T3). Conjunctival cultures were obtained at timepoints T2 and T3.

RESULTS

A 1-day application of topical levofloxacin significantly reduced (p = 0.0004) the number of eyes with positive conjunctival cultures from 41 eyes (82%) to 23 eyes (46%). Similarly, a 3-day application significantly reduced (p = 0.0001) the positive culture rate from 37 eyes (74%) to 17 eyes (34%). Two drops of povidone-iodine further reduced the positive culture rate for both groups to 20% (10 eyes for each group). There was no significant difference in positive culture rate between the 1-day and 3-day groups at T0 (p = 0.4689), T1 (p = 0.3074), T2 (p = 0.6706), or T3 (p = 1.000).

CONCLUSIONS

The application of topical 0.5% levofloxacin for 1 or 3 days significantly reduced the number of eyes with positive conjunctival cultures. The addition of 5% povidone-iodine further eliminated bacteria from the conjunctiva. The application of levofloxacin for 1 day appears to be as effective as a 3-day application.

Endophthalmitis prophylaxis

The prevalence of postoperative endophthalmitis following cataract surgery appears to be increasing with the popularity of clear cornea incision. As a result, endophthalmitis prophylaxis will play and increasingly important role as the number of clear cornea cataract surgeries increases. In this article, the authors examine and critically evaluate techniques used to prevent endophthalmitis including proper preoperative patient preparation, application of povidone-iodine, and use of broad-spectrum antibiotics (topical, intracameral, and subconjunctival injection).

Wirksamkeit neuer Fluorchinolone gegenüber der bakteriellen Normalflora der Bindehaut

BACKGROUND

Our aim was to determine the antibiotic susceptibility of the preoperative conjunctival bacterial flora against 25 commonly used antibiotics, especially the new fluoroquinolones levofloxacin, gatifloxacin, and moxifloxacin.

PATIENTS AND METHODS

The Kirby-Bauer disk-diffusion technique was used to test for the in vitro antibiotic susceptibility of conjunctival bacterial strains isolated from 160 patients (median=74 years, mean=71 years) undergoing cataract surgery at the Department of Ophthalmology, Stanford University, CA, USA.

RESULTS

Among the 256 bacteria isolated, 201 (79%) were coagulase-negative staphylococci (CNS), 26 Staphylococcus aureus, 15 Streptococcus group D and 14 gram-negative rods. A total of 100 of these 256 strains (39%) were classified as multiresitant (resistant to>or=five antibiotics). The resistance rate (RR) of commonly used antibiotics for all CNS was: gatifloxacin=moxifloxacin<gentamycin=tobramycin=levofloxacin=neomycin<ciprofloxacin=ofloxacin<erythromycin. The RR for S. aureus and the gram-negative rods was low and insignificant in comparison to the other antibiotics tested. None of the Streptococcus group D were resistant to gatifloxacin, levofloxacin, or moxifloxacin, however, they were highly resistant (RR over 30%) to the other antibiotics. Some 50% of the bacteria were resistant to erythromycin.

CONCLUSION

Newer generation fluoroquinolones provide excellent efficacy against coagulase-negative staphylococci and Streptococcus group D despite a high number of multiresitant bacteria.

Glucose Permeability of Human, Bovine, and Porcine Corneas in vitro

PURPOSE

To measure glucose flux across human, bovine, and porcine corneas and to determine the diffusion coefficient of each type of cornea.

METHODS

Diffusion of glucose across human (n = 8), bovine (n = 7), and pig corneas (n = 8) was measured using a modified blind well chamber apparatus (Boyden chamber). Dialysis membranes (n = 7) and nonporous Mylar membranes (n = 7) were used as positive and negative controls, respectively. Glucose concentrations were measured at 30-min intervals with a commercially available glucose meter.

RESULTS

The diffusion of glucose through corneas in vitro was calculated by a simple Fickian diffusion model. The diffusion coefficient of glucose is highest for the human cornea (D(HC) = 3.0 +/- 0.2 x 10(-6) cm(2)/s) followed by porcine corneas (D(PC) = 1.8 +/- 0.6 x 10(-6) cm(2)/s) and bovine corneas (D(BC) = 1.6 +/- 0.1 x 10(-6) cm(2)/s) (p < 0.05). The diffusion coefficients of all tested corneas were significantly higher (p < 0.05) than that of dialysis membrane (D(DM) = 3.4 +/- 0.2 x 10(-7) cm(2)/s).

CONCLUSION

The glucose diffusion coefficients of human, bovine, and porcine corneas are on the order of 10(-6). Human corneas have higher permeability to glucose than either porcine or bovine corneas.

Prospective randomized study determining whether a 3-day application of ofloxacin results in the selection of fluoroquinolone-resistant coagulase-negative Staphylococcus

PURPOSE

To determine whether a 3-day application of ofloxacin results in the selection of fluoroquinolone-resistant conjunctival coagulase-negative Staphylococcus.

DESIGN

Prospective randomized trial.

METHODS

Patients scheduled for ocular surgery were randomized to a control (89 eyes) or study group (70 eyes). The study group received topical ofloxacin (0.3%) four times a day for 3 days. Conjunctival cultures were obtained at baseline (T0) and after 3 days of ofloxacin (T1). Cultures were also obtained at T0 and T1 for the control group, but these eyes did not receive an antibiotic. Bacteria isolated were identified and antibiotic susceptibility was determined.

RESULTS

At T0, 53 out of 89 patients (60%) in the control and 48 out of 70 patients (69%) in the study group harbored coagulase-negative Staphylococcus. Among these coagulase-negative Staphylococcus, 12 out of 53 in the control and 11 out of 48 in the study group were resistant to ofloxacin (p>0.9999). At T1, significantly fewer coagulase-negative Staphylococcus (p=0.0003) were isolated from the study group (18 coagulase-negative Staphylococcus), compared the control group (48 coagulase-negative Staphylococcus). Of these, 5 out of 17 coagulase-negative Staphylococcus in the study group and 9 out of 48 coagulase-negative Staphylococcus in the control group were resistant to ofloxacin (p=0.5649). There was no significant difference in the number of coagulase-negative Staphylococcus resistant to ciprofloxacin or norfloxacin in the study group compared to the control group at T1.

CONCLUSIONS

Ofloxacin given four times a day for 3 days does not select out for conjunctival fluoroquinolone-resistant coagulase-negative Staphylococcus.

Clinical results of topical fluconazole for the treatment of filamentous fungal keratitis

BACKGROUND

Fungal keratitis is a rare but serious condition that may result in loss of vision. The potentially poor prognosis might be due to a delay in diagnosis and/or to limited treatment options. The aim of this study is to evaluate the clinical outcome of patients treated with topical fluconazole 0.2% for the treatment of filamentous fungal keratitis.

METHODS

Retrospective case series. A chart review of all patients evaluated at the Ophthalmology Department of the Hospital de Clínicas in Paraguay from January 1997 to December 2000 identified 25 cases of fungal keratitis. Among these cases, one patient discontinued the treatment and another received amphotericin as the first line drug, resulting in 23 cases available for data analysis. Twelve patients were treated with topical fluconazole 0.2% alone (Group I) and 11 patients received a combination of topical fluconazole 0.2% and oral ketoconazole 200 mg twice daily (Group II).

RESULTS

Sixteen of 23 cases showed resolution of the keratitis, 9/12 (75%) in Group I and 7/11 (64%) in Group II. Seven patients (30%) did not respond to medical treatment and required a surgical procedure to preserve eye integrity. Superficial and small ulcers have a significantly better prognosis than do lrge and deep ulcers. Concomitant oral ketoconazole (400 mg/day) did not improve the clinical results.

CONCLUSIONS

Our findings of study suggest that topical fluconazole 0.2% is a safe and effective antifungal drug for the management of filamentous mycotic keratitis, particularly in cases that are not severe. The addition of oral ketoconazole to topical fluconazole did not improve the clinical outcome.

Normal ocular flora in newborns delivered in two hospital centers in Argentina and Paraguay

PURPOSE

To determine the spectrum of normal conjunctival flora in newborns in two hospital centers in North Argentina and Paraguay.

METHODS

In this prospective observational study, conjunctival specimens were obtained from the right eyes of newborns prior to the application of any topical medications. Culture samples were also obtained from the cervicovaginal secretions of the infants' mothers. All samples were directly inoculated into culture media and all growth were identified and quantified.

RESULTS

Among the 190 newborns studied, 126 were delivered vaginally and 64 via caesarean section (C-section). A total of 180 different bacterial strains were acquired from the vaginally delivered infants and 77 from the C-section group (P=0.078, Student's t-test). Conjunctival cultures obtained within one hour of birth showed that 85 out of 101 samples (84%) from both the vaginal and C-section group had positive cultures, compared to 84 out of 89 samples (94%) obtained more than 1 h after birth (P<0.001). Among the vaginally delivered newborns, the most common bacteria isolated were coagulase-negative Staphylococcus (in 69 samples, 38%), Propionibacterium spp (36, 20%) and Corynebacterium spp (29, 16%). In the CES, the most common isolates were coagulase-negative Staphylococcus (39, 51%), Propionibacterium spp (22, 29%) and Staphylococcus aureus (6, 8%). There was a significantly higher proportion of gram-positive rods (P=0.017) isolated from infants delivered vaginally (16%) than from those delivered by C-section (5%). No Neisseria gonorrhoeae were isolated in conjunctival samples. Among the 130 organisms isolated from cervicovaginal secretions in 81 out of 189 mothers, the most common organisms were Lactobacillus spp. (47%), Corynebacterium spp (21%), Gardnerella vaginalis (15%), and Candida spp (14%). No Neisseria gonorrhoeae or Chlamydia trachomatis were found in cervicovaginal samples.

CONCLUSION

The most common conjunctival bacteria in newborns delivered by either vaginal birth or C-section were coagulase-negative Staphylococcus. The proportion of positive conjunctival cultures was higher for infants delivered vaginally than for C-section delivery.