Should central serous chorioretinopathy be added to the list of ocular side effects of phosphodiesterase 5 inhibitors?

Central serous chorioretinopathy: An evidence-based treatment guideline

Central serous chorioretinopathy (CSC) is a relatively common disease that causes vision loss due to macular subretinal fluid leakage and it is often associated with reduced vision-related quality of life. In CSC, the leakage of subretinal fluid through defects in the retinal pigment epithelial layer's outer blood-retina barrier appears to occur secondary to choroidal abnormalities and dysfunction. The treatment of CSC is currently the subject of controversy, although recent data obtained from several large randomized controlled trials provide a wealth of new information that can be used to establish a treatment algorithm. Here, we provide a comprehensive overview of our current understanding regarding the pathogenesis of CSC, current therapeutic strategies, and an evidence-based treatment guideline for CSC. In acute CSC, treatment can often be deferred for up to 3-4 months after diagnosis; however, early treatment with either half-dose or half-fluence photodynamic therapy (PDT) with the photosensitive dye verteporfin may be beneficial in selected cases. In chronic CSC, half-dose or half-fluence PDT, which targets the abnormal choroid, should be considered the preferred treatment. If PDT is unavailable, chronic CSC with focal, non-central leakage on angiography may be treated using conventional laser photocoagulation. CSC with concurrent macular neovascularization should be treated with half-dose/half-fluence PDT and/or intravitreal injections of an anti-vascular endothelial growth factor compound. Given the current shortage of verteporfin and the paucity of evidence supporting the efficacy of other treatment options, future studies-ideally, well-designed randomized controlled trials-are needed in order to evaluate new treatment options for CSC.

Effects of systemic drugs on the development and progression of age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of severe loss of central vision among people over 50. The pathophysiology of the disease is multifactorial and can be attributed to genetics, aging, inflammation, environmental factors, and lifestyle factors including smoking, diet, obesity, and alcohol consumption. While there is no treatment for dry AMD, the current standard treatment for wet AMD is an intraocular injection of anti-vascular endothelial growth factor-an effective, yet expensive, therapy that requires ongoing treatment. As the aging population continues to grow, and AMD diagnoses continue to rise, new treatments should be explored to reduce vision complications and decrease treatment burdens. Many systemic conditions have progressive pathological changes that may affect AMD, particularly those affecting systemic vasculature like diabetes and cardiovascular status. Consequently, systemic drugs used to treat coexistent systemic diseases may influence some of the pathogenic mechanisms of AMD and lead its progression or delay. In this review we explore the current literature to summarize the findings of the reported effects of antihypertensive, immunosuppressants, cholesterol lowering agents, nonsteroidal anti-inflammatory drugs, dopamine precursors, hypoglycemic agents, and anticoagulants on AMD.

Sildenafil in ophthalmology: An update

Sildenafil citrate, a selective oral phosphodiesterase 5 inhibitor, is a widely used drug for erectile dysfunction that acts by elevating cGMP levels and causing smooth muscle relaxation. It also has 10% activity against PDE6, a key enzyme in phototransduction cascade in the retina. Recent ocular imaging developments have further revealed the influence of sildenafil on ocular hemodynamics, particularly choroidal perfusion. Choroidal thickness is increased, and choroidal perfusion is also enhanced by autoregulatory mechanisms that are further dependent on age and microvascular abnormalities. Studies demonstrating high intraocular pressure via a "parallel pathway" from increased choroidal volume and blood flow to the ciliary body have challenged previous concepts. Another new observation is the effect of sildenafil on bipolar cells and cyclic-nucleotide gated channels. We discuss potential deleterious effects (central serous chorioretinopathy, glaucoma, ischemic optic neuropathy, and risks to recessive carriers of retinitis pigmentosa), potential beneficial effects (ameliorate choroidal ischemia, prevent thickening of Bruch membrane, and promote recovery of the ellipsoid zone) in macular degeneration, as well as potential drug interactions of sildenafil.

[Central serous chorioretinopathy]

Central serous chorioretinopathy (CSC) is the fourth most common disease of the macula after age-related macular degeneration, diabetic retinopathy and retinal vein occlusion and a cause of irreversible visual loss. This article gives an overview of the epidemiology, risk factors, pathophysiology, clinical presentation, multimodal imaging and discusses current therapeutic options for CSC.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FINDINGS OF MICROVASCULAR AND NEURAL CHANGES IN PRIMARY PULMONARY HYPERTENSION

PURPOSE

To investigate the microvascular and neural changes in primary pulmonary hypertension (PPH) patients compared with healthy controls.

METHODS

Forty-four eyes of 22 PPH patients were included in this observational clinical cohort study, and 44 eyes of 22 healthy participants were enrolled as controls. Optical coherence tomography angiography images were obtained from each participant using the RTVue XR Avanti device with AngioVue software 2.0.

RESULTS

Regarding the total macular-associated vessel density, including that of the superficial and deep retina, the optic disk-associated capillary density, including that of the whole image, capillary density inside the disk, and the peripapillary region, was significantly lower in the PPH group than in the control group. There was a similar trend in the retinal nerve fiber layer thickness and the ganglion cell complex thickness, whereas the focal loss volume and the global loss volume were greater in the PPH group than the control group.

CONCLUSION

Changes in the capillary density and thickness of the retina and the optic nerve head in PPH patients can be detected by optical coherence tomography angiography. Parameters including the macular-associated vessel density, optic disk-associated capillary density, retinal nerve fiber layer, ganglion cell complex, focal loss volume, and global loss volume may provide useful evidence for the early detection of microvascular and neural impairments in patients with PPH.

Visual Side Effects Linked to Sildenafil Consumption: An Update

Phosphodiesterase type 5 (PDE5) inhibitors such as Viagra^® (sildenafil citrate) have demonstrated efficacy in the treatment of erectile dysfunction (ED) by inducing cyclic guanosine monophosphate (cGMP) elevation followed by vasodilation and increased blood flow. It also exerts minor inhibitory action against PDE6, which is present exclusively in rod and cone photoreceptors. The effects of sildenafil on the visual system have been investigated in a wide variety of clinical and preclinical studies due to the fact that a high dose of sildenafil may cause mild and transient visual symptoms in some patients. A literature review was performed using PubMed, Cochrane Library and Clinical Trials databases from 1990 up to 2020, focusing on the pathophysiology of visual disorders induced by sildenafil. The aim of this review was not only to gather and summarize the information available on sildenafil clinical trials (CTs), but also to spot subpopulations with increased risk of developing undesirable visual side effects. This PDE inhibitor has been associated with transient and reversible ocular side effects, including changes in color vision and light perception, blurred vision, photophobia, conjunctival hyperemia and keratitis, and alterations in the electroretinogram (ERG). Sildenafil may induce a reversible increase in intraocular pressure (IOP) and a few case reports suggest it is involved in the development of nonarteritic ischemic optic neuropathy (NAION). Reversible idiopathic serous macular detachment, central serous retinopathy and ERG disturbances have been related to the significant impact of sildenafil on retinal perfusion. So far, sildenafil does not seem to cause permanent toxic effects on chorioretinal tissue and photoreceptors as long as the therapeutic dose is not exceeded and is taken under a physician’s direction to treat a medical condition. However, the recreational use of sildenafil can lead to harmful side effects, including vision changes.

Effects of phosphodiesterase type 5 inhibitors on choroid and ocular vasculature: a literature review

To provide information on the effects of phosphodiesterase type 5 (PDE5) inhibitors on choroidal vessels and central serous chorioretinopathy (CSC) and possible implications for development of exudative age-related macular degeneration (AMD). Two independent investigators conducted a qualitative review of PubMed to identify studies on the choroidal effect of PDE5 inhibitors in June 2019. The search used key words that included PDE5 inhibitors, sildenafil, tadalafil, vardenafil, choroid, choroidal flow, choroidal vessels, choroidal thickness, CSC, AMD or a combination. Only studies which assessed choroidal findings were included. Many ocular diseases are related to changes in choroidal thickness and perfusion. Patients with AMD, who have decreased choroidal perfusion, may manifest more severely diminished choroidal ability to deliver oxygen and other metabolites to the retina, leading to growth of neovascular tissue. As a result of this engorgement of the choroidal vasculature, some patients may have leakage across the retinal pigment epithelium (RPE) and accumulation of subretinal fluid, resulting in CSC. Transient visual symptoms, i.e., changes in color perception and increased light sensitivity, are well-known adverse effects, but there have been rare reports of vision-threatening ocular complications in users of PDE5 inhibitors, such as nonarteritic anterior ischemic optic neuropathy and cilioretinal artery occlusion. The choroid is a vascular tissue analogous in many respects to the corpus cavernosum, and PDE5 inhibitors may increase the choroidal thickness and perfusion. While it is intuitively obvious that thickness of the choroid alone does not guarantee better choriocapillaris oxygenation, it is a reasonable step towards ameliorating ischemia. These drugs have numerous physiologic effects on the choroid related to blood flow, such as clinical consequences in CSC and AMD.

ACUTE SEROUS RETINAL DETACHMENT IN IDIOPATHIC PULMONARY ARTERIAL HYPERTENSION

PURPOSE

To report the case of a 44-year-old woman with acute transient visual loss likely because of idiopathic pulmonary arterial hypertension.

METHODS

Case report imaged with fundus photographs, spectral-domain optical coherence tomography, fundus autofluorescence, and fluorescein and indocyanine green angiographies.

RESULTS

The patient complained of unilateral vision loss with metamorphopsia. Fundus examination of the right eye showed serous macular detachment and retinal folds. Fluorescein angiography and indocyanine green angiography showed delayed choroidal filling with multiple choroidal perfusion defects and dye leakage from areas of multiple pigment epithelial detachments. Spectral-domain optical coherence tomography showed a thick choroid. Medical history included idiopathic pulmonary arterial hypertension treated with tadalafil. Ocular signs regressed spontaneously within 1 week.

CONCLUSION

Transient severe choroidal filling defects with subretinal exudation may be observed in idiopathic pulmonary arterial hypertension. The present case raised the questions of the triggering factor of the acute decompensation of the blood-retinal barrier and the cause of its spontaneous regression.

Anethum graveolens Linn. (dill) extract enhances the mounting frequency and level of testicular tyrosine protein phosphorylation in rats

OBJECTIVE

To investigate the effect of Anethum graveolens (AG) extracts on the mounting frequency, histology of testis and epididymis, and sperm physiology.

METHODS

Male rats induced by cold immobilization before treating with vehicle or AG extracts [50, 150, and 450 mg/kg body weight (BW)] via gastric tube for consecutive 1, 7, and 14 d were examined for mounting frequency, testicular phosphorylation level by immunoblotting, sperm concentration, sperm acrosome reaction, and histological structures of testis and epididymis, respectively.

RESULTS

AG (50 mg/kg BW) significantly increased the mounting frequency on Days 1 and 7 compared to the control group. Additionally, rat testis treated with 50 mg/kg BW AG showed high levels of phosphorylated proteins as compared with the control group. In histological analyses, AG extract did not affect the sperm concentration, acrosome reaction, and histological structures of testis and epididymis.

CONCLUSIONS

AG extract enhances the aphrodisiac activity and is not harmful to sperm and male reproductive organs.

Central serous chorioretinopathy: update on pathophysiology and treatment

Recent technological advances--new pathophysiological insights, new imaging techniques for diagnosis and management, and new treatments--have led to an improved understanding of central serous chorioretinopathy (CSC). The primary role of the choroid has become more widely accepted with widespread use of indocyanine green angiography. Optical coherence tomography (OCT), and particularly enhanced depth imaging OCT, demonstrate a thickened and engorged choroid. Adaptive optics, fundus autofluorescence, multifocal electroretinography, microperimetry, and contrast sensitivity testing reveal that patients with even a mild course suffer previously undetected anatomic and functional loss. Although focal laser and photodynamic therapy are the current standard of care for persistent subretinal fluid in CSC, they are not appropriate in all cases, and the optimal timing of intervention remains unclear.

Central serous chorioretinopathy: a review of epidemiology and pathophysiology

Central serous chorioretinopathy (CSCR) is a common retinal cause of vision loss. This review surveys the epidemiology, risk factors, clinical presentation, natural history and pathophysiology of CSCR. Studies suggest an annual incidence rate of 10 per 100 000 in men, with CSCR occurring six times more commonly in men compared with women. Most acute CSCR cases resolve spontaneously within 2-3 months. Prognosis is highly dependent on presenting visual acuity; patients with initial visual acuities of 6/6 remain at that level, while patients with initial visual acuities of less than 6/9 recover on average two to three Snellen lines over the next few years. The main risk factors for CSCR are systemic corticosteroid use, type A personality, pregnancy and endogenous Cushing's syndrome. The pathophysiology of CSCR remains obscure, although disorders in both the choroidal circulation and retinal pigment epithelium are implicated.

ADMET considerations for phosphodiesterase-5 inhibitors

INTRODUCTION

ADMET (absorption, distribution, metabolism, excretion, and toxicity) profiling is an important aspect of all drug developments. The pharmaceutical industry must always consider ADMET properties in order to optimize drug candidates and to introduce new formulations against existing marketed drugs. Consequently, candidate drug development may be halted early in the discovery phase or during the more costly drug development process because of their poor ADMET properties.

AREAS COVERED

The main focus of this article is ADMET profiling, pharmacokinetic (PK) drug interactions, mechanisms and possible adverse drug reactions (ADRs) for approved phosphodiesterase-5 inhibitors (PDE5Is). The authors also look at the efficacy and non-erectogenic benefits of current PDE5Is, which are widely used by patients with erectile dysfunction (ED). The authors also discuss other unapproved PDE5Is such as aildenafil and udenafil, which are currently in use in clinical trials.

EXPERT OPINION

The authors believe that the enhancing effect of PDE5Is on the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway means that PDE5Is could be used to treat various conditions. An important issue in their development is 'cross-talk' between PDE5 and other PDEs and thus their specificity for other PDEs. But while it might be difficult to achieve the ideal ADMET profile, it should not necessarily prevent further development of a lead PDE5I. The risk assessment of PDE5Is, with respect to their ADMET properties, is therefore very important for predicting drug-drug interactions, possible side effects, ADRs and its future clinical applications.