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The role of topical non-steroidal anti-inflammatory drugs (NSAIDs) in routine cataract surgery has been established since decades. Topical NSAIDs have been shown to reduce postoperative ocular inflammation and pain, preserve intraoperative mydriasis, and reduce the risk of postoperative cystoid macular oedema, whilst carrying a very low side-effect profile. Nepafenac is one of the currently available topical NSAIDs. The studies have shown that is has a high ocular penetration, allowing for potentially better results than other NSAIDs. This review gathers the current literature on the role of nepafenac in cataract surgery aiming to help surgeons maximise the benefits of its use to achieve improved surgical outcomes.

We report an unusual case of a missed intraocular foreign body, which was incidentally discovered in the anterior chamber drainage angle of the left eye of a retired masonry worker, some 30 years after the inciting injury. The ocular penetration and intraocular foreign body were missed during initial emergency management, despite the high-velocity mechanism of chiselling granite, which was reported. This case effectively highlights the need for a careful history and examination in high-velocity injuries to the eye (such as those caused by hammering and grinding), a high index of suspicion for intraocular foreign bodies, and considers best practice in managing such presentations.

Commercial topical ocular formulations for hydrophobic actives rely on the use of suspensions or oil in water emulsions and neither of these formulation modalities adequately promote drug penetration into ocular tissues. Using the ocular relevant hydrophobic drug, cyclosporine A (CsA), a non-irritant ocular penetration enhancer is showcased, which may be used for the formulation of hydrophobic actives. The activity of this penetration enhancer is demonstrated in a healthy rabbit model. The Molecular Envelope Technology (MET) polymer (N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan), a self-assembling, micelle-forming polymer, was used to formulate CsA into sterile filtered nanoparticulate eye drop formulations and the stability of the formulation tested. Healthy rabbits were dosed with a single dose of a MET–CsA (NM133) 0.05% formulation and ocular tissues analyzed. Optically clear NM133 formulations were prepared containing between 0.01–0.1% w/v CsA and 0.375–0.75% w/v MET polymer. NM133 0.01%, NM133 0.02% and NM133 0.05% were stable for 28 days when stored at refrigeration temperature (5–6 °C) and room temperature (16–23 °C), but there was evidence of evaporation of the formulation at 40 °C. There was no change in drug content when NM133 0.05% was stored for 387 days at 4 °C. On topical dosing to rabbits, corneal, conjunctival and scleral AUC0–24 levels were 25,780 ng.h g−1, 12,046 ng.h g−1 and 5879 ng.h g−1, respectively, with NM133 0.05%. Meanwhile, a similar dose of Restasis 0.05% yielded lower values of 4726 ng.h/g, 4813 ng.h/g and 1729 ng.h/g for the drug corneal, conjunctival and scleral levels, respectively. NM133 thus delivered up to five times more CsA to the ocular surface tissues when compared to Restasis. The MET polymer was non-irritant up to a concentration of 4% w/v. The MET polymer is a non-irritant ocular penetration enhancer that may be used to deliver hydrophobic drugs in optically clear topical ocular formulations.

Dry eye disease (DED) is one of the most common ocular surface disorders characterised by a deficiency in quality and/or quantity of the tear fluid. Due to its multifactorial nature involving several inter-related underlying pathologies, it can rapidly accelerate to become a chronic refractory condition. Therefore, several therapeutic interventions are often simultaneously recommended to manage DED efficiently. Typically, artificial tear supplements are the first line of treatment, followed by topical application of medicated eyedrops. However, the bioavailability of topical eyedrops is generally low as the well-developed protective mechanisms of the eye ensure their rapid clearance from the precorneal space, thus limiting ocular penetration of the incorporated drug. Moreover, excipients commonly used in eyedrops can potentially exhibit ocular toxicity and further exacerbate the signs and symptoms of DED. Therefore, formulation development of topical eyedrops is rather challenging. This review highlights the challenges typically faced in eyedrop development, in particular, those intended for the management of DED. Firstly, various artificial tear supplements currently on the market, their mechanisms of action, as well as their application, are discussed. Furthermore, formulation strategies generally used to enhance ocular drug delivery, their advantages and limitations, as well as their application in commercially available DED eyedrops are described.

Ocular diseases can deteriorate vision to the point of blindness and thus can have a major impact on the daily life of an individual. Conventional therapies are unable to provide absolute therapy for all ocular diseases due to the several limitations during drug delivery across the blood-retinal barrier, making it a major clinical challenge. With recent developments, the vast number of publications undergird the need for nanotechnology-based drug delivery systems in treating ocular diseases. The tool of nanotechnology provides several essential advantages, including sustained drug release and specific tissue targeting. Additionally, comprehensive in vitro and in vivo studies have suggested a better uptake of nanoparticles across ocular barriers. Nanoparticles can overcome the blood-retinal barrier and consequently increase ocular penetration and improve the bioavailability of the drug. In this review, we aim to summarize the development of organic and inorganic nanoparticles for ophthalmic applications. We highlight the potential nanoformulations in clinical trials as well as the products that have become a commercial reality.

To investigate the ocular penetration of natamycin (NAT) and voriconazole (VRC) after topical instillation in New Zealand white rabbits using simplified liquid chromatography-tandem mass spectrometry (LC-MS/MS) and high-performance liquid chromatography.Seventy-eight healthy rabbits were randomly divided into 3 groups. In the first 2 groups, 72 rabbits were used for single-dose testing (36 for NAT, 36 for VRC), in which 50 μL of 5.0% NAT or 1.0% VRC was instilled into the rabbits' left eyes. In the 3rd group, 6 rabbits were used for repeated-dose testing in which 50 μL of 5.0% NAT was instilled into their left eyes 12 times (once per hour) during the daytime. These animals were sacrificed immediately to collect their aqueous humors and corneas.After a single topical instillation, the highest concentrations in the cornea and aqueous humor for VRC were 34.1 μg/g and 14.7 μg/mL, respectively. The permeability ratios of aqueous/cornea were from 0.1 to 1.26. The highest concentrations in cornea and aqueous humor for NAT were 299.3 ng/g and 27.1 ng/mL, respectively. The permeability ratios of aqueous/cornea were from 0.02 to 0.23. In the repeated-dose group, the NAT concentrations in the cornea and aqueous humor were 10,569 ng/g and 54.4 ng/mL, respectively. The permeability ratio was as low as 0.0051.The better corneal penetration of VRC suggests that it is more suitable for deep corneal fungal infections than NAT via topical ocular administration.

AIM: To evaluate ocular penetration of topically applied 1% tigecycline. METHODS: Forty-two New Zealand White rabbits were divided into 3 groups. A 50 μL drop of 1% tigecycline was administered in group 1. In groups 2 and 3, the drop was administered every 15min for 60min (keratitis protocol). Aqueous humor samples in groups 1 and 2 were collected under general anesthesia at 15, 30, 45, 60, 120, and 180min after the last drop. All animals in group 3 were euthanatized. Cornea, vitreous and blood samples were collected 60 and 120min after the last drop. Tigecycline concentrations were measured using high performance liquid chromatography-mass spectrometry (LC-MS/MS). RESULTS: The peak aqueous humor tigecycline concentration [mean 0.73±0.14 mg/L (SD) and 2.41±0.14 mg/L, respectively] occurred 45min after topical drug application in groups 1 and 2. Group 3 mean values in the cornea, and vitreous, were 3.27±0.50 µg/g, and 0.17±0.10 mg/L at 60min and 3.17±0.77 µg/g and 0.20±0.07 mg/L at 120min, respectively. Tigecycline serum concentrations were negligible. CONCLUSION: Tigecycline levels in the aqueous humor in groups 1 and 2, and in the cornea in group 3 exceeded the minimum inhibitory concentrations of most gram-positive organisms that cause bacterial keratitis and endophthalmitis.

Models of animal are the most appropriate method for assessments of human in-vivo percutaneous and ocular penetrations. Monkey and rodents are used for the same. There are several nuts and bolts of each one, so it is necessary to study each one separately. Monkey, porcine and guinea pig penetration are correlated with that of human skin. The skin of rodents, lupus, pigs, etc. has more penetration properties than human skin. Rabbit, goat and sheep eye are mostly used for ocular penetration. The researcher also used hen's egg chorioallantoic membrane test for ocular irritation study. The other animals' cornea, cul-de-sac, eyeballs and prepared corneal epithelial models are very less in practice. Web-based alternative non-animal models are also available instead of animal models too. This article describes characteristics of monkeys, pigs, rats, rabbits, guinea pigs and hairless rodents, HuSki model, Cellophane® membrane, egg membrane, gelatin membrane, animal models for ophthalmic delivery, hen's egg chorioallantoic membrane test, prepared corneal epithelial models and web-based alternative non-animal database.

Retrobulbar anesthesia is still used before ocular surgery; however, it has various complications including ocular penetration. The penetration/perforation of the globe can cause complications such as endophthalmitis, retinal detachment, and scotoma. Choroidal neovascularization (CNV) is rarely seen, following choroidal rupture in penetrating eye injuries. Here, we present a patient who underwent a pars plana vitrectomy for vitreous hemorrhage secondary to ocular penetration during a retrobulbar injection for cataract surgery. This patient later developed CNV at the penetration site during follow-up. Physicians should remember that CNV can occur as an unusual late complication of ocular penetration during retrobulbar anesthesia.

Purpose: To evaluate the penetration of topical tacrolimus 0.05% into the aqueous humor. Observations: A total of four patients scheduled for routine cataract surgery were included prospectively. We excluded patients with corneal pathology or ocular surface diseases. Topical tacrolimus 0.05% was compounded at our facility. It was dosed every 1 min for 5 min an hour before the aqueous was sampled. Aqueous samples were collected at the time of cataract surgery and were subjected to detection of presence and level of tacrolimus. There were 2 male and 2 female patients. The age range was 58–73 years with a mean age of 66 years. Tacrolimus was detected in the aqueous humor in all patients. The concentration of tacrolimus in the aqueous ranged from 2.6 to 5.6 ng/ml (mean 4.15 ± 1.18 ng/ml). In all patients, the aqueous tacrolimus concentration was greater than the minimal therapeutic level. The study was registered at clinicaltrials.gov (registration number is NCT02794610). Conclusions and Importance: Tacrolimus was detected in the aqueous humor following topical application. Topical tacrolimus may be a promising steroid-sparing modality for the treatment of anterior uveitis. Keywords: Topical tacrolimus, Ocular penetration, Ocular inflammation

The eye is an important organ, it provides vision and it is an important component of our facial identity (1,2). There is an old saying “ The eye is the window of the soul ”, clear and bright eyes bring esthetic pleasure to people. Human eye is globular and consists of two main parts, the anterior and posterior segments (1,2). Although the posterior part of the eye is comfortably located in the orbit, they are delicate because its anterior segment including the cornea is exposed to the outside world, thus accessible to wear and tear. To protect and maintain the eye functions while reduce the disruptions from outside and inside the body, the eyes are equipped with defense mechanisms for both the anterior and posterior segments (1,2). For the cornea region, the eyes are associated with precorneal factors including eyelids, tear film, blinking, tear turnover, induced lacrimation and nasolacrimal drainage. Cornea itself contains multilayers of corneal epithelial cells with tight junctions, which severely limit ocular penetration of molecules (3,4). For intraocular environment (mostly the posterior parts), it contains two main barriers, blood-aqueous and blood-retina barrier with epithelial and endothelial tight junctions, which restrict penetration of molecules into the intraocular chamber (5). All these features make the eye an isolated and well-protected organ, however, they also make it hard to treat during ocular diseases (1,2).

BACKGROUND: Little is known about the ocular penetration of echinocandin antifungals. We studied the ocular distribution of systemically administered caspofungin in a rabbit uveitis model. METHODS: Caspofungin (1 mg/kg per day) was given intravenously to rabbits as a single dose or as repeated daily doses on 7 days starting 24 h after induction of unilateral uveitis by intravitreal endotoxin injection. Caspofungin concentrations were determined by high-performance liquid chromatography in the cornea, aqueous humor, vitreous humor, and serum 4, 8, 16, and 24 h after administration of a single dose and 24 h after the last of seven doses. RESULTS: The mean caspofungin concentration in the aqueous of the inflamed eye 4 and 8 h after single-dose administration was 1.30 +/- 0.39 mug/ml and 1.12 +/- 0.34 mug/ml, respectively. Drug concentrations decreased to 0.24 +/- 0.09 mug/ml at 16 h and 0.26 +/- 0.14 mug/ml at 24 h. In the vitreous of inflamed eyes drug levels were undetectable at all time points. No drug was found in the aqueous of inflamed eyes 24 h after the last of seven repeated doses, and the vitreous only contained trace amounts. In the corneas of inflamed eyes concentrations reached 1.64 +/- 0.48 mug/g at 4 h, peaked at 2.16 +/- 1.14 mug/g at 8 h, and declined to 1.87 +/- 0.52 mug/g and 1.49 +/- 0.48 mug/g at 16 and 24 h, respectively. After repeated dosing, corneal concentrations of caspofungin were 0.8 and 1.0 mug/g and below the limit of detection in two of four animals. In non-inflamed eyes no drug was detectable in the aqueous and vitreous humor, and the corneas at any time point. CONCLUSIONS: In our model, caspofungin reached therapeutically relevant levels in the aqueous and cornea but not in the vitreous humor of inflamed eyes. Intraocular drug deposition was critically dependent on a disrupted blood-eye barrier. These findings suggest a limited role for caspofungin in the treatment of fungal endophthalmitis.

I would like to discuss some concerns that have been raised by the paper recently published by Volk et al. (2019) entitled “Ophthalmic complications following ocular penetration during routine dent...

In recent years, discovery of the cannabinoid receptors in the ocular tissues has opened up the possible utility of tetrahydrocannabinol (THC) and other cannabinoids in the management of several ocular diseases and conditions. The biopharmaceutical characteristics of THC, however, do not favor transmembrane diffusion. Additional physiological barriers, atypical of ocular drug delivery, makes THC delivery to the ocular tissues through the topical route even more challenging. Thus, careful formulation design and consideration is needed to translate the potential of THC into the preclinical and clinical settings. This chapter reviews some of the ocular conditions that can be impacted by THC, and the barriers to its delivery through the topical route. Strategies to improve ocular penetration of THC have also been discussed.

To evaluate the ocular pharmacokinetics of clarithromycin (CLA) eye drops topically applied to the corneas of rabbits.One 50-μL drop of CLA (0.25%) was administered to each New Zealand white rabbit in a single dose group, and one 50-μL drop of CLA was administered 6 times at 5-min intervals to each rabbit in a loading dose group. The effect of debridement on corneal penetration was also investigated in a de-epithelium group. The drug concentrations in the cornea and aqueous humor (AH) were assayed using high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) analysis.Maximum CLA levels were achieved in the corneas and AH at 15 and 60 min, respectively, in the intact epithelium eyes in the single dose group (24.54±10.64 μg/g and 0.78±0.22 μg/mL, respectively, mean±the standard error of the mean, n=8). In the loading dose group, 30 min after the last application, the CLA level in the corneas reached 92.26±17.62 μg/g. In the loading dose group, the drug levels in the corneas and AH were significantly increased compared with the drug levels in the corneas with the intact epithelium and de-epithelium eyes in the single dose group at the corresponding time points (P0.05). The estimated CLA half-lives in the corneas and AH for the intact eyes were 103.28 and 132.61 min, respectively.Therapeutic CLA levels can be achieved in rabbit corneas after topically applying the drug with eye drops.

To evaluate the ocular penetration of ISV-304 (ketorolac tromethamine) formulated in DuraSite(®) or DuraSite(®) 2 compared to Acular LS(®) (0.4% ketorolac ophthalmic solution) in rabbits.The left eye of rabbits received a single topical instillation of either ISV-304 (0.2% and 0.4% ketorolac) in DuraSite, ISV-304 (0.2% and 0.4% ketorolac) in DuraSite 2, or Acular LS. At predetermined time points, aqueous humor (AH) levels of ketorolac were measured by HPLC-MS/MS, and Cmax, Tmax, and AUC0.25-24h were determined.The highest mean concentration of ketorolac was achieved in ISV-304 (0.4%) formulated in DuraSite 2 with a Cmax value of 1889 ± 884 ng/mL, compared to Cmax values for ISV-304 (0.4%) formulated in DuraSite (1212 ± 435 ng/mL) or Acular LS (275 ± 83 ng/mL). ISV-304 (0.2%) formulations also achieved higher AH Cmax values (801 ± 205 ng/mL and 1077 ± 415 ng/mL) compared to Acular LS. There was a significant increase in drug exposure in the ISV-304 (0.4%) formulated in DuraSite 2 or DuraSite formulations with AUC0.25-24h values 6836 ng/mL*h and 5684 ng/mL*h, respectively, compared to Acular LS with an AUC0.25-24h value of 1424 ng/mL*h. ISV-304 (0.2%) formulations also had high AUC0.25-24h values (3241 ng/mL*h and 4490 ng/mL*h), which were a 2.3-3.2-fold increase over the Acular LS AUC0.25-24h value.DuraSite and DuraSite 2 delivery systems markedly improved the ketorolac ocular pharmacokinetic parameters in rabbits. DuraSite formulations may lessen the side effects associated with topical nonsteroidal anti-inflammatory drug use by maintaining efficacy with a reduced dosing regimen and reduced active ingredient.

Charu Sharma,1,2 Nihar R Biswas,1 Shreesh Ojha,3 Thirumurthy Velpandian1 1Department of Ocular Pharmacology and Pharmacy, All India Institute of Medical Sciences, New Delhi, India; 2Department of Internal Medicine, 3Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, AlAin, UAE Objective: Corneal permeability of drugs is an important factor used to assess the efficacy of topical preparations. Transcorneal penetration of drugs from aqueous formulation is governed by various physiological, physiochemical, and formulation factors. In the present study, we investigated the effect of formulation factors like concentration, pH, and volume of instillation across the cornea using cassette dosing technique for ophthalmic fluoroquinolones (FQs). Materials and methods: Sterile cocktail formulations were prepared using four congeneric ophthalmic FQs (ofloxacin, sparfloxacin, pefloxacin mesylate, and gatifloxacin) at concentrations of 0.025%, 0.5%, and 0.1%. Each formulation was adjusted to different pH ranges (4.5, 7.0, and 8.0) and assessed for transcorneal penetration in vivo in rabbit’s cornea (n=4 eyes) at three different volumes (12.5, 25, and 50µL). Aqueous humor was aspirated through paracentesis after applying local anesthesia at 0, 5, 15, 30, 60, 120, and 240minutes postdosing. The biosamples collected from a total of 27 groups were analyzed using liquid chromatography–tandem mass spectroscopy to determine transcorneal permeability of all four FQs individually. Results: Increase in concentration showed an increase in penetration up to 0.05%; thereafter, the effect of concentration was found to be dependent on volume of instillation as we observed a decrease in transcorneal penetration. The highest transcorneal penetration of all FQs was observed at pH 7.0 at concentration 0.05% followed by 0.025% at pH 4.5. Lastly, increasing the volume of instillation from 12.5 to 50µL showed a significant fall in transcorneal penetration. Conclusion: The study concludes that formulation factors showed discernible effect on transcorneal permeation; therefore, due emphasis should be given on drug development and design of ophthalmic formulation. Keywords: transcorneal penetration, ophthalmic, in vivo, antibacterial

Simon P Kelly, Graham MB ReevesThe Royal Bolton Hospital, Bolton, UKPurpose: To consider the potential for ocular injury from writing implements by presenting four such cases, and to consider the incidence of such eye injuries from analysis of a national trauma database.Methods: The Home and Leisure Accident Surveillance System was searched for records of eye injuries from writing instruments to provide UK estimates of such injuries. Four patients with ocular penetrating injury from pens or pencils (especially when caused by children), and examined by the authors, are described which illustrate mechanisms of injury.Results: It is estimated that around 748 ocular pen injuries and 892 ocular pencil injuries of undetermined severity occurred annually in the UK during the database surveillance period 2000–2002. No eye injuries from swords, including toy swords and fencing foils, were reported.Conclusion: Ocular perforation sometimes occur from writing instruments that are thrown in the community, especially by children. Implications for policy and prevention are discussed. Non-specialists should have a low threshold for referring patients with eye injuries if suspicious of ocular penetration, even where caused by everyday objects, such as writing instruments.Keywords: eye injury, eye, children, mechanism, writing instruments, prevention

The pharmacokinetics of linezolid (LZD) was investigated in rabbit eyes after single and multiple oral administrations.Pharmacology Laboratory, University Hospital of Strasbourg, Strasbourg, France.Twelve New Zealand rabbits were divided into 2 groups: an oral dose of 120 mg (35 mg/kg) was administrated in group 1 (n=6), and a multiple-dose protocol targeting the steady state (120 mg twice a day for 3 days) was given in group 2 (n=6). Serum (s) and vitreous (v) samples were collected after 0, 30, and 45 min and after 1, 2, 4, 6, 8, and 12 h. LZD concentrations were measured by high-performance liquid chromatography.LZD exhibited a mean C(max) in serum of 13.9±4.5 (standard deviation) mg/L after a T(max) of 1 h in group 1 and 18.0±6.5 mg/L after a T(max) of 30 min in group 2. The vitreal peak occurred at 2 h in both groups with an intraocular C(max) of 3.0±1.3 mg/L in group 1 and 4.5±1.4 mg/L in group 2. The resulting area under the concentration-time curve in vitreous at the steady state compared with the area under the concentration-time curve calculated after a single dose increased significantly (28.7±7.7 vs. 18.3±2.1 mg·h/L, respectively, p0.05). The time that serum concentration exceeded the minimum inhibitory concentrations (TMIC) in group 2 was eventually40% for MIC up to 3 mg/L in rabbit vitreous.Although a single oral dose produced intraocular concentrations barely sufficient to induce bacterial eradication, a multiple-dose regimen provided intraocular levels exceeding the MICs of most Gram-positive organisms responsible for endophthalmitis.

Over the past two decades, many oral drugs have been designed in consideration of physicochemical properties to attain optimal pharmacokinetic properties. This strategy significantly reduced attrition in drug development owing to inadequate pharmacokinetics during the last decade. On the other hand, most ophthalmic drugs are generated from reformulation of other therapeutic dosage forms. Therefore, the modification of formulations has been used mainly as the approach to improve ocular pharmacokinetics. However, to maximize ocular pharmacokinetic properties, a specific molecular design for ocular drug is preferable. Passive diffusion of drugs across the cornea membranes requires appropriate lipophilicity and aqueous solubility. Improvement of such physicochemical properties has been achieved by structure optimization or prodrug approaches. This review discusses the current knowledge about ophthalmic drugs adapted from systemic drugs and molecular design for ocular drugs. I propose the approaches for molecular design to obtain the optimal ocular penetration into anterior segment based on published studies to date.

Herein, the authors present a retrospective case report of a patient with ocular penetration due to cocaine-induced midline destructive lesion. To their knowledge, this is the first documented case of ocular penetration secondary to cocaine insufflation.

Objective To investigate intraocular penetration of orally administered doxycycline in the normal equine eye and to compare intraocular and serum doxycycline concentrations. Procedures Six mares were administered doxycycline at 10 mg/kg every 12 h by nasogastric tube for 5 days. Blood, aqueous, and vitreous samples were collected on days 1 and 5. All samples were assayed for doxycycline concentrations. Aqueous and vitreous samples were also assayed for protein quantitation. Results Doxycycline was rapidly absorbed after the first dose (Tmax value of 1.42 ± 1.28 h); and elimination of doxycycline occurred slowly (median t1/2 = 10.88 h). Doxycycline could not be detected in the aqueous on days 1 and 5, nor could it be detected in the vitreous on day 1. On day 5, the mean vitreous doxycycline concentration was 0.17 ± 0.04 µg/mL at 2 h after drug administration. Conclusions Repeated oral administration of doxycycline in the horse resulted in steady state serum concentrations of