A case of nonarteritic ischemic optic neuropathy (NAION) in a male patient taking sildenafil

Phosphodiesterase Type 5 Inhibitors and Visual Side Effects: A Narrative Review

Phosphodiesterase type 5 inhibitors such as sildenafil citrate and tadalafil are well known for the treatment of erectile dysfunction. However, their use in the presence of pulmonary hypertension can cause ophthalmologic side effects, including non-arteritic optic ischemic neuropathy, chorioretinopathy, glaucoma, and optic atrophy. The present review aimed to identify these visual side effects and provide recommendations. We identified articles published from January 2000 to March 2019 on diseases arising from the management of sexual dysfunction in urology or pulmonary hypertension in pneumonia that could cause pathologic alterations in eye structure based on a literature search of the MEDLINE electronic database using keywords for the most common adverse effects and different kinds of phosphodiesterase 5 inhibitors. After applying the exclusion criteria, we selected 36 of the 77 articles initially identified to write the narrative review and added 20 additional articles to completely describe the pathological entities. Phosphodiesterase type 5 inhibitors can cause side effects in the eye including ocular surface abnormalities, increased intraocular pressure and glaucoma, uveitis, non-arteritic ischemic neuropathy, chorioretinopathy, retinal occlusion, and visual field changes. There is an increased need for well-performed studies to better understand these side effects, which are common due to the wide use of sildenafil.

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.

Association between phosphodiesterase-5 inhibitors and nonarteritic anterior ischemic optic neuropathy

BACKGROUND

Use of phosphodiesterase-5 (PDE-5) inhibitors has been reported to be a risk factor for development of nonarteritic anterior ischemic optic neuropathy (NAION) in males, based largely on a number of case reports. The objective of our study was to determine whether men who use this class of medications are more likely than a matched control group to develop NAION.

METHODS

A pharmacoepidemiological nested case-control study was used to examine the above association in a health claims database of physician diagnoses and prescription medication dispensing. Cases of NAION were matched with corresponding controls and correlated with the use of PDE-5 inhibitors. A conditional logistic regression model was used to estimate rate ratios for development of NAION with use of PDE-5 inhibitors.

RESULTS

A total of 1,109 cases of NAION were found and matched to 1,237,290 controls identified within the database. Cases were more likely to have hyperlipidemia, diabetes, hypertension, myocardial infarction, and cerebrovascular accident in the year preceding their NAION. The adjusted rate ratio for any use of PDE-5 inhibitor in the year before the NAION was 1.01 (95% confidence interval [CI], 0.79-1.28); recent use of a PDE-5 inhibitor in the 30 days before the NAION also had no significant association, with an adjusted rate ratio of 0.96 (95% CI, 0.75-1.23). Results for individual PDE-5 inhibitors did not achieve statistical significance.

CONCLUSIONS

Our results do not suggest any association between having a prescription filled for PDE-5 inhibitor medication and receiving a diagnosis code for NAION. This is consistent with other studies in the literature that have failed to elucidate a plausible mechanism by which these drugs might compromise circulation at the optic nerve head.

Ischemic optic neuropathy

Anterior ischemic optic neuropathy (AION) is a common cause of visual loss in patients over 50 years of age. Optical coherence tomography has provided new information which may have implications regarding future approaches to management.

Nonarteritic anterior ischaemic optic neuropathy

PURPOSE OF REVIEW

There have been many reports in recent literature concerning the use of scanning laser polarimetry, Heidelberg retinal tomography and optical coherence topography in assessing the optic nerve and peripapillary nerve fibre layer. It is important to assess the validity of new equipment and see whether this has improved our understanding of the disease. There are also reports about possible association of nonarteritic anterior ischaemic optic neuropathy with cataract surgery and phosphodiesterase type-5 inhibitors. This review attempts to look at some of the techniques used and possible associations with nonarteritic anterior ischaemic optic neuropathy.

RECENT FINDINGS

Scanning laser polarimetry, Heidelberg retinal tomography and optical coherence tomography have been helpful in quantifying optic nerve and peripapillary retinal nerve fibre layer defects, with different efficacy and limitations. Although these confirm the damage to retinal nerve fibre layer beyond what is detected by standard visual field examination, the effect of cataract surgery and phosphodiesterase type-5 inhibitors remains to be further studied on a larger scale. The few experimental treatments for nonarteritic anterior ischaemic optic neuropathy also need further confirmatory studies.

SUMMARY

More studies are required to evaluate the benefits of new imaging methods. The availability of a primate model may provide clues to assessing experimental treatments for nonarteritic anterior ischaemic optic neuropathy.

Erectile dysfunction drugs and risk of anterior ischaemic optic neuropathy: casual or causal association?

Phosphodiesterase type 5 (PDE5) inhibitor drugs for erectile dysfunction have revolutionised the treatment of male sexual dysfunction and are among the best selling drugs worldwide. Several cases of non-arteritic anterior ischaemic optic neuropathy (NAION) have been reported since 2005 in users of these agents. NAION is a sudden irreversible cause of visual loss with a poorly understood aetiology that affects up to 10 adults per 100,000 each year. Following a series of such case reports, WHO and FDA have labelled the association between use of PDE5 inhibitors and risk of NAION as "possibly" causal. There have been several recent studies of this association, including a rechallenge case report and a large managed care database study. However, the inability to confirm or refute claims of an association between NAION and EDD is generating clinical and regulatory uncertainty. Questions surrounding use of PDE5 inhibitors and risk of NAION highlight weaknesses in current systems used to identify and evaluate uncommon adverse effects of medication use. This paper reviews all the recent evidence on PDE5 inhibitors and the risk of NAION.

Anterior ischemic optic neuropathy and stroke with use of PDE-5 inhibitors for erectile dysfunction: cause or coincidence?

The PDE-5 inhibitors sildenafil (Viagra) vardenafil (Levitra) and tadalafil (Cialis) have been taken by millions of men for erectile dysfunction. Transient visual symptoms are common but there also have been fourteen cases of nonarteritic anterior ischemic optic neuropathy (NAION) described in patients using these drugs as well as a few other vascular events. NAION is a common optic neuropathy in patients in the age group using these drugs and the question arises whether or not PDE-5 inhibitors are causing NAION. One case of NAION occurred after transient visual symptoms occurred with repeated use and one patient experienced a transient ischemic attack after taking a dose followed by a stroke on using the drug again later. Other than these two cases with strong dechallenge-rechallenge data, the evidence to support PDE-5 inhibitors as a cause of NAION or any vascular event is weak. PDE-5 inhibitors probably are a rare cause of a common ischemic disorder of the optic disc. They should be avoided in men who have already experienced NAION in one eye. Patients should be warned to seek medical attention if they have visual field or acuity loss after using PDE-5 inhibitors. Otherwise there is little basis for modifying the current guidelines for the use of these drugs.

Sildenafil citrate use and the incidence of nonarteritic anterior ischemic optic neuropathy

Nonarteritic anterior ischemic optic neuropathy (NAION) has been reported rarely in men after taking sildenafil or other phosphodiesterase 5 inhibitors for erectile dysfunction (ED). The incidence of NAION in men receiving sildenafil treatment for ED was estimated using pooled safety data from global clinical trials and European observational studies. Based on clinical trial data in more than 13,000 men and on more than 35,000 patient-years of observation in epidemiologic studies, we estimated an incidence of 2.8 cases of NAION per 100,000 patient-years of sildenafil exposure. This is similar to estimates reported in general US population samples (2.52 and 11.8 cases per 100,000 men aged >or=50 years). The data cited herein do not suggest an increased incidence of NAION in men who took sildenafil for ED.

Ocular Safety in Patients Using Sildenafil Citrate Therapy for Erectile Dysfunction

Sildenafil citrate improves erectile function in men with erectile dysfunction (ED) by selectively inhibiting cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5), which is present in all vascular tissue. Sildenafil also has a weaker inhibitory action on PDE6, located in the rod and cone photoreceptors. Modest, transient visual symptoms, typically blue tinge to vision, increased brightness of lights, and blurry vision, have been reported with sildenafil use and occur more frequently at higher doses. Visual function studies in healthy subjects and in patients with eye disease suggest that sildenafil does not affect visual acuity, visual fields, and contrast sensitivity. Transient, mild impairment of color discrimination can occur around the time of peak plasma levels. Spontaneous postmarketing reports of visual adverse events, including nonarteritic anterior ischemic optic neuropathy (NAION), have been reported during the 7 years that sildenafil has been prescribed to more than 27 million men worldwide. However, because men with ED frequently have vascular risk factors that may also put them at increased risk for NAION, a causal relationship is difficult to establish. No consistent pattern has emerged to suggest any long-term effect of sildenafil on the retina or other structures of the eye or on the ocular circulation.

Erectile Dysfunction Drugs and Non-Arteritic Anterior Ischemic Optic Neuropathy: Is There a Cause and Effect Relationship?

The recent reports of non-arteritic anterior ischemic optic neuropathy (NAION) occurring shortly after ingestion of erectile dysfunction agents have raised the question of whether these agents have a cause-and-effect relationship to NAION. The nature of optic nerve head blood flow and the various factors that influence it, the systemic vascular effects of these agents, and the clinical features of NAION lead me to believe that these agents are contributory factors. Patients with the appropriate risk factors should, therefore, be warned of this possibility and advised to refrain from using these agents.

Effect of Viagra on the foveolar choroidal circulation of AMD patients

To investigate the effects of sildenafil citrate (Viagra) on foveolar choroidal circulation in patients with age related macular degeneration (AMD). Double-blinded, randomized, placebo-controlled, crossover study. Fifteen male AMD patients received a dose of 100 mg of sildenafil or matching placebo on two separate days. Laser Doppler flowmetry was performed to assess relative choroidal blood velocity (ChB(Vel)), volume (ChB(Vol)) and flow (ChB(Flow)) in the study eye prior to administration of the drug at baseline and 30, 90, 180, 300 min after dosing. Best corrected visual acuity (BCVA), contrast sensitivity (CS), mean arterial blood pressure (BPm), heart rate (HR), intraocular pressure (IOP) and ocular perfusion pressure (PP) were determined. In comparison to placebo, sildenafil did not cause any statistically significant changes in mean ChB(Vel) (ANOVA, P=0.12), ChB(Vol) (ANOVA, P=0.24) or ChB(Flow) (ANOVA, P=0.46). There were no statistically significant changes in CS (ANOVA, P=0.59), BCVA (P=0.58), IOP (P=0.81) or HR (P=0.07) throughout the study. Significant decreases in BPm (P=0.006) and PP (P=0.006) were observed at 30 min after sildenafil. Administration of sildenafil citrate didn't cause any statistically significant changes in the foveolar choroidal circulation of AMD patients.

Nonarteritic Ischemic Optic Neuropathy Developing Soon After Use of Sildenafil (Viagra): A Report of Seven New Cases

Seven patients, aged between 50 and 69 years, had typical features of nonarteritic anterior ischemic optic neuropathy (NAION) within 36 hours after ingestion of sildenafil citrate (Viagra) for erectile dysfunction. Six patients had vision loss within 24 hours after use of the agent. Final visual acuity in the affected eye ranged from 20/20 to light perception. Both eyes were affected in one individual. All affected individuals had pre-existing hypertension, diabetes, elevated cholesterol, or hyperlipidemia. Seven similar cases have been previously reported. Sildenafil may provoke NAION in individuals with an arteriosclerotic risk profile.

Visual impairment after laparoscopic donor nephrectomy

Loss of vision after surgery is rare and has never been reported after a laparoscopic procedure. We describe a case of visual deficits secondary to posterior ischemic optic neuropathy after a laparoscopic donor nephrectomy. The potential etiologies of postoperative visual loss are reviewed, and recommendations for avoiding this complication are discussed.

Evaluation of the safety of sildenafil for male erectile dysfunction: experience gained in general practice use in England in 1999

OBJECTIVE

To examine the safety of sildenafil, the first of the phosphodiesterase type 5 inhibitors licensed for the treatment of male erectile dysfunction (ED), as used in general medical practice in England, quantifying the incidence of a range of events in patients treated with sildenafil, and identifying any previously unrecognized adverse drug reactions.

METHODS

In a postmarketing observational cohort study using prescription-event monitoring (PEM), exposure data were derived from dispensed prescription details for patients who started treatment between April and August 1999. Outcome data were derived from "green form" questionnaires (GFs) returned by general practitioners (GPs). RESULTS In all, 24 835 (54.7%) of GFs posted to GPs were returned, of which 22 473 contained useful data for 22 471 male and two female patients. The major primary indications/clinical context of prescribing were impotence (16 583, 73.8%) and diabetes mellitus (183, 0.8%); 145 events were reported as adverse drug reactions to sildenafil. GPs recorded 3951 reasons for stopping sildenafil, and ischaemic heart disease (IHD) in 135 patients was the commonest clinical reason reported. The clinical condition reported most frequently in the first month of observation was diabetes mellitus and/or hyperglycaemia (in 99 events). A standardized mortality ratio (SMR) for deaths caused by IHD in the first 8893 of 22 473 patients was 31.41 (95% confidence interval 18.29-50.29), using the comparator population of males in England in 1998.

CONCLUSION

This study identified the safety profile of sildenafil as used in the community, showing no unexpected events. The SMR analysis of deaths from IHD provided no evidence to suggest a higher incidence of deaths in the study cohort than in the male population in England.