Barbara Wirostko

Age-related macular degeneration and the aging eye

Age-related macular degeneration (AMD) is an ocular disease that causes damage to the retinal macula, mostly in the elderly. Normal aging processes can lead to structural and blood flow changes that can predispose patients to AMD, although advanced age does not inevitably cause AMD. In this review, we describe changes that occur in the macular structure, such as the retinal pigment epithelium and Bruch’s membrane, with advancing age and in AMD. The role of genetics in AMD and age-related changes in ocular blood flow that may play a role in the pathogenesis of AMD are also discussed. Understanding the pathophysiology of AMD development can help guide future research to further comprehend this disease and to develop better treatments to prevent its irreversible central vision loss in the elderly.

Anterior Eye Segment Drug Delivery Systems: Current Treatments and Future Challenges

New technologies for delivery of drugs, such as small molecules and biologics, are of growing interest among clinical and pharmaceutical researchers for use in treating anterior segment eye disease. The challenge is to deliver effective drugs at therapeutic concentrations to the targeted ocular tissue with minimal side effects. To achieve this, a better understanding of the unmet needs, what is required of the various methods of delivery to achieve successful delivery, and the potential challenges of anterior segment drug delivery is necessary and the primarily aim of this review. This review covers the various physiological and anatomical barriers that exist for effective delivery to the targeted tissue of the eye, the pathological conditions of the anterior segment, and the unmet needs for treatment of these ocular diseases. Second, it reviews the novel delivery technologies that have the potential to maintain and/or improve the drugs therapeutic index and improving both patient adherence for chronic therapy and potential patient outcomes. This review bridges the pharmaceutical and clinical research/challenges and provides a detailed overview of anterior segment drug delivery accomplishments thus far, for researchers and clinicians.

The role of transforming growth factor β in glaucoma and the therapeutic implications.

Glaucoma is a progressive optic neuropathy frequently associated with elevated intraocular pressure, ocular vascular changes and extracellular matrix remodelling at the optic nerve head and in the trabecular meshwork. The pathogenesis is multifactorial and complex, but many recent studies have suggested that transforming growth factor-β (TGF-β) plays a major role in the process. Significantly elevated levels of TGF-β have been identified in the anterior chamber of glaucomatous eyes. TGF-β has also been shown to directly cause increased intraocular pressure. It is believed that this occurs through complex interaction with the trabecular meshwork, leading to decreased aqueous humour outflow. These processes occur through specific interactions with various proteins and signalling molecules also present in ocular tissues. By understanding the role that TGF-β plays in the pathogenesis of glaucoma, alternative therapeutic agents can be developed, which target these pathways and improve and assist in the management of disease. This review will cover previous investigative studies and discuss the current understanding of TGF-βs role in glaucoma and how it may serve as a potential therapeutic target.

Thiolated hyaluronan-based hydrogels crosslinked using oxidized glutathione: an injectable matrix designed for ophthalmic applications.

Future ophthalmic therapeutics will require the sustained delivery of bioactive proteins and nucleic acid-based macromolecules and/or provide a suitable microenvironment for the localization and sustenance of reparative progenitor cells after transplantation into or onto the eye. Water-rich hydrogels are ideal vehicles for such cargo, but few have all the qualities desired for novel ophthalmic use, namely in situ gelation speed, cytocompatibility, biocompatibility and capacity to functionalize. We describe here the development of an ophthalmic-compatible crosslinking system using oxidized glutathione (GSSG), a physiologically relevant molecule with a history of safe use in humans. When GSSG is used in conjunction with an existing hyaluronate-based, in situ crosslinkable hydrogel platform, gels form in less than 5 min using the thiol-disulfide exchange reaction. This GSSG hydrogel supports the 3-D culture of adipose-derived stem cells in vitro and shows biocompatibility in preliminary intracutaneous and subconjunctival experiments in vivo. In addition, the thiol-disulfide exchange reaction can also be used in conjunction with other thiol-compatible chemistries to covalently link peptides for more complex formulations. These data suggest that this hydrogel could be well suited for local ocular delivery, focusing initially on front of the eye therapies. Subsequent uses of the hydrogel include delivery of back of the eye treatments and eventually into other soft, hyaluronan-rich tissues such as those from the liver and brain.

Ocular safety of sildenafil citrate when administered chronically for pulmonary arterial hypertension: results from phase III, randomised, double masked, placebo controlled trial and open label extension

Objective To assess the ocular effects and safety profile of chronic sildenafil oral dosing in patients with pulmonary arterial hypertension. Design 12 week, double masked, randomised, placebo controlled, phase III trial with open label extension. Setting 53 institutions worldwide. Participants 277 adults with idiopathic pulmonary arterial hypertension or pulmonary arterial hypertension associated with connective tissue disease or after congenital heart disease repair (mean pulmonary artery pressure ≥25 mm Hg; pulmonary capillary wedge pressure ≤15 mm Hg at rest). Interventions During the double masked study, oral sildenafil 20 mg, 40 mg, or 80 mg or placebo (1:1:1:1) three times daily for 12 weeks was added to baseline drug treatment. In the extension study, the placebo, 20 mg and 40 mg groups received 40 mg three times daily titrated to 80 mg three times daily at week 6. After unmasking, the dose was titrated according to clinical need. Main outcome measure Ocular safety (ocular examinations, visual function tests, participants’ reports of adverse events, and visual disturbance questionnaire completed by investigators) by treatment group at 12 weeks, 24 weeks, 18 months, and yearly. Results Findings of the objective assessments—that is, intraocular pressure and visual function tests (visual acuity, colour vision, and visual field)—were similar across groups (20 mg, n=69; 40 mg, n=67; 80 mg, n=71; placebo, n=70). No clinically significant changes occurred between baseline and 12 weeks, except for an efficacy signal in contrast sensitivity for the sildenafil 40 mg three times daily group. In right eyes, changes in intraocular pressure from baseline to week 12 ranged from a mean of −0.5 (95% confidence interval −1.3 to 0.2) mm Hg with placebo, −0.2 (−0.9 to 0.5) mm Hg with sildenafil 40 mg, and −0.1 (−0.7 to 0.5) mm Hg with 80 mg to 0.3 (−0.4 to 0.9) mm Hg with sildenafil 20 mg (the approved dose for pulmonary arterial hypertension). Mean changes from baseline to week 12 in contrast sensitivity in right eyes were −0.02 (SD 0.12) in the sildenafil 20 mg three times daily group compared with −0.05 (0.18) in the placebo group (P=0.044). Percentages of participants with deterioration in visual acuity (Snellen) from baseline to week 12 ranged from 10% (n=7) in the placebo group to 3% (n=2) in the sildenafil 20 mg three times daily group; the same percentages had visual field changes from normal to abnormal during the period in these two groups. The investigators did not deem any findings on colour vision assessment to be clinically significant. Findings of the objective assessments in the 40 mg and 80 mg three times daily sildenafil treatment groups and in left eyes were not substantially different, nor were any measures different throughout the open label extension compared with week 12. However, objective data were limited after month 18, as most participants had missing data or visual parameters were no longer collected by investigators. Incidence of ocular adverse events reported on the case report forms and assessed by the investigator was low with all doses, but a modest, dose related incidence of chromatopsia, cyanopsia, photophobia, and visual disturbance was reported with 80 mg three times daily consistent with the indicated dosing for erectile dysfunction. Retinal haemorrhages, captured on funduscopy, occurred in 2% (4/207) of sildenafil treated participants and none in the placebo group during the double masked study and in 4% (10/259) during the open label extension. Conclusions Sildenafil dosing up to 80 mg three times daily is safe and well tolerated from an ocular perspective in patients with pulmonary arterial hypertension. Daily chronic dosing in this patient population was not associated with visual change and had no detrimental effect on best corrected visual acuity, contrast sensitivity, colour vision, or visual field, or on slit lamp examinations, funduscopy, or intraocular pressure during the duration of this study. Trial registration Clinical trials NCT00644605 and NCT00159887.

Ocular Drug Delivery for Glaucoma Management

Current glaucoma management modalities are hindered by low patient compliance and adherence. This can be due to highly complex treatment strategies or poor patient understanding. Treatments focus on the management or reduction of intraocular pressure. This is most commonly done through the use of daily topical eye drops. Unfortunately, despite effective therapies, glaucoma continues to progress, possibly due to patients not adhering to their treatments. In order to mitigate these patient compliance issues, many sustained release treatments are being researched and are entering the clinic. Conjunctival, subconjunctival, and intravitreal inserts, punctal plugs, and drug depots are currently in clinical development. Each delivery system has hurdles, yet shows promise and could potentially mitigate the current problems associated with poor patient compliance.

Impaired ocular blood flow regulation in patients with open‐angle glaucoma and diabetes

Background:  To elucidate the potential impact of diabetes mellitus on primary open‐angle glaucoma pathology through vascular deficiency.

Latanoprost systemic exposure in pediatric and adult patients with glaucoma: a phase 1, open-label study.

OBJECTIVE To evaluate short-term safety and steady-state systemic pharmacokinetics (PK) of latanoprost acid in pediatric subjects with glaucoma or ocular hypertension who received the adult latanoprost dose. DESIGN Phase 1, open-label, multicenter study. PARTICIPANTS Pediatric patients of 3 age groups (<3, 3-<12, and 12-<18 years) and adults (≥18 years) receiving latanoprost ophthalmic solution 0.005% once daily in 1 or both eyes for ≥2 weeks. INTERVENTION Latanoprost was administered in both eyes each morning post-screening. Subjects returned 3 to 28 days later for evaluation of plasma concentrations, withholding morning latanoprost. At the clinic, a single drop of latanoprost ophthalmic solution was instilled into both eyes. Plasma latanoprost acid concentrations were collected predose and 5, 15, 30, and 60 minutes after administration. MAIN OUTCOME MEASURES Latanoprost acid plasma exposure. RESULTS The evaluable PK analysis set included data from 39 of 47 enrolled subjects. The median peak plasma concentration value was higher in the <3-year age group (166 pg/ml) versus other groups (49, 16, and 26 pg/ml for the 3-<12-year, 12-<18-year, and ≥18-year age groups, respectively). The median area under the concentration-time curve from zero to last measurable concentration value was also higher in the <3-year age group (2716 pg/min/ml) versus other groups (588, 106, and 380 pg/min/ml for the 3-<12-year, 12-<18-year, and ≥18-year age groups, respectively). Latanoprost acid was rapidly eliminated from the blood, with plasma concentrations undetectable within 10 to 30 minutes postdose in all but the <3-year age group. There were no discontinuations or dose reductions due to adverse events or treatment-emergent adverse events. CONCLUSIONS Latanoprost acid systemic exposure was higher in younger children versus adolescents and adults, attributed primarily to lower body weight and smaller blood volume. Latanoprost acid was eliminated rapidly in all age groups and resulted in only a brief period of systemic exposure after once-daily dosing. Higher systemic exposure was not accompanied by adverse events, and on the basis of extrapolation of safety data from adults, this pilot study suggests an adequate safety margin for systemic adverse effects with use of the adult topical dose of latanoprost in pediatric patients. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosures may be found after the references.

Chronic orbital inflammatory disease: parasitisation of orbital leucocytes by mollicute-like organisms.

Chronic orbital inflammatory disease (COID) is usually considered non-infectious and idiopathic. Treatment is empirical, palliative, and may not prevent disease progression. COID occurs in isolation or in association with various systemic diseases. Exophthalmos may be an important presenting sign. Vasculitis, lymphoid infiltrates, and granulomas are common. Mollicute-like organisms (MLO) parasitising and destroying vitreous leucocytes are often found to cause human chronic uveitis when an appropriate search is made. Inoculation of these MLO into mouse eyelids produced chronic uveitis and exophthalmic orbital inflammatory disease. Mollicutes are cell wall deficient bacteria. Extracellular mollicutes cause human and animal diseases characterised by lymphoid infiltrates, immunosuppression, and autoantibody production. Intracellular morphologically similar bacteria are non-cultivable pathogens termed MLO. Identification is based on direct detection in diseased cells by transmission electron microscopy. MLO are cytopathogenic and detection is aided by the alterations they produce. MLO replace the cytoplasm, destroy the organelles, and alter the nucleus. This results in cell proliferation, destruction, and dysfunction. MLO parasitise lymphocytes, monocytes, and polymorphonuclear leucocytes. This report describes orbital leucocytes parasitised by MLO in three patients with isolated COID. Rifampicin treatment of MLO disease is discussed.

Generic medications in ophthalmology

The purpose of this review is to discuss the process of genericisation of medications in the US and Europe with a focus on ophthalmic drugs. Regulatory guidelines of the US Food and Drug Administration and the European Medicines Agency will be discussed, and the advantages and concerns of genericisation will be explored. We will look at various studies concerning the safety and efficacy of generic drugs compared to their branded counterparts. In particular, the challenges of assuring bioequivalence and therapeutic equivalence in topical ophthalmic drugs will be examined.