Sequential, non-arteritic anterior ischemic optic neuropathy in patients taking sildenafil: a report of ten cases

Non-Arteritic Anterior Ischemic Optic Neuropathy Associated With the Use of Phosphodiesterase Type 5 Inhibitors: A Literature Review

Phosphodiesterase type 5 (PDE5) inhibitors are frequently used for erectile dysfunction (ED) as the first line of treatment. This medication was initially developed to treat muscle spasms and pulmonary hypertension. The United States Food and Drug Administration (FDA) approved its usage for treating ED. Sildenafil, tadalafil, vardenafil, and avanafil are PDE5 inhibitors. The decrease of cyclic guanosine monophosphate (cGMP) in smooth muscle cells caused by sildenafil causes smooth muscle relaxation and penile erection. Vasodilation of the blood vessels reduces perfusion and blood flow to the optic nerve and eye. Several incidences of non-arteritic anterior ischemic optic neuropathy (NAION) have been recorded in sildenafil users, among other ocular complications. The onset of NAION is usually sudden and painless, and it is associated with any pattern of visual field loss. Possible symptoms include poor visual acuity, diminished color vision, a visual field defect, or hemorrhages in the form of flames. Nevertheless, NAION pathogenesis is still a mystery. Most visual effects are reversible weeks after the medication is stopped, and NAION does not seem to cause a permanent blindness. A small cup-to-disc ratio (disc at risk) and underlying systemic illnesses, such as hypertension, increase the risk of developing NAION. An early indicator of cardiovascular disease is ED. NAION diagnosis is challenging due to a lack of confirmatory diagnostic evidences. Normal visual acuity does not exclude NAION from being a possibility. In order to evaluate visual outcomes in NAION, data on both visual acuity (VA) and the full peripheral visual field are needed. Treatment with steroids did not seem to improve visual results.

Non-arteritic anterior ischaemic optic neuropathy (NA-AION) and COVID-19 vaccination

A woman in her 50s presented with diminution of vision in her left eye (OS) 4 days after COVISHIELD^TM vaccination. She had been diagnosed with non-arteritic anterior ischaemic optic neuropathy (NA-AION) of right eye (OD) 8 months earlier. The present episode revealed a best-corrected visual acuity (BCVA) of 20/50 in OD and 20/20 in OS with grade 1 relative afferent pupillary defect. Fundus evaluation showed pale disc in OD and temporal disc oedema in OS. Humphrey’s visual field analysis showed incomplete inferior altitudinal defect in OD and a centro-caecal scotoma in OS. Systemic investigations were normal. OS was diagnosed with NA-AION. She was started on oral aspirin 75 mg. At 1-month follow-up, disc oedema of OS had resolved with BCVA maintaining at 20/20. The patient was lost to follow-up later. The relationship between the vaccine and the ocular event is temporal with no causal association.

Non-invasive positive airway pressure therapy for improving erectile dysfunction in men with obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea syndrome (OSAS) is associated with several chronic diseases, including erectile dysfunction (ED). The association of OSAS and ED is far more common than might be found by chance; the treatment of OSAS with non-invasive positive airway pressure therapy is associated with improvement of respiratory symptoms, and may contribute to the improvement of associated conditions, such as ED.

OBJECTIVES

To assess the effectiveness and acceptability of non-invasive positive airway pressure therapy for improving erectile dysfunction in OSAS.

SEARCH METHODS

We identified studies from the Cochrane Airways Trials Register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, AMED EBSCO, and LILACS, the US National Institutes of Health ongoing trials register ClinicalTrials.gov, and the World Health Organisation international clinical trials registry platform to 14 June 2021, with no restriction on date, language, or status of publication. We checked the reference lists of all primary studies, and review articles for additional references, and relevant manufacturers' websites for study information. We also searched specific conference proceedings for the British Association of Urological Surgeons; the European Association of Urology; and the American Urological Association to 14 June 2021.

SELECTION CRITERIA

We considered randomised controlled trials (RCTs) with a parallel or cross-over design, or cluster-RCTs, which included men aged 18 years or older, with OSAS and ED. We considered RCTs comparing any non-invasive positive airway pressure therapy (such as continuous positive airways pressure (CPAP), bilevel positive airway pressure (BiPAP), variable positive airway pressure (VPAP), or similar devices) versus sham, no treatment, waiting list, or pharmacological treatment for ED. The primary outcomes were remission of ED and serious adverse events; secondary outcome were sex-related quality of life, health-related quality of life, and minor adverse events.

DATA COLLECTION AND ANALYSIS

Two review authors independently conducted study selection, data extraction, and risk of bias assessment. A third review author solved any disagreement. We used the Cochrane RoB 1 tool to assess the risk of bias of the included RCTs. We used the GRADE approach to assess the certainty of the body of evidence. To measure the treatment effect on dichotomous outcomes, we used the risk ratio (RR); for continuous outcomes, we used the mean difference (MD). We calculated 95% confidence intervals (CI) for these measures. When possible (data availability and homogeneous studies), we used a random-effect model to pool data with a meta-analysis.

MAIN RESULTS

We included six RCTs (all assessing CPAP as the non-invasive positive airway pressure therapy device), with a total of 315 men with OSAS and ED. All RCTs presented some important risk of bias related to selection, performance, assessment, or reporting bias. None of included RCTs assessed the ED remission rate, and we used the provided ED mean scores as a proxy. CPAP versus no CPAP There is uncertainty about the effect of CPAP on mean ED scores after 4 weeks, using the International index of erectile function (IIEF-5, higher = better; MD 7.50, 95% CI 4.05 to 10.95; 1 RCT; 27 participants; very low-certainty evidence), and after 12 weeks (IIEF-ED, ED domain; MD 2.50, 95% CI -1.10 to 6.10; 1 RCT; 57 participants; very low-certainty evidence, downgraded due to methodological limitations and imprecision). There is uncertainty about the effect of CPAP on sex-related quality of life after 12 weeks, using the Self-esteem and relationship test (SEAR, higher = better; MD 1.00, 95% CI -8.09 to 10.09; 1 RCT; 57 participants; very low-certainty evidence, downgraded due to methodological limitations and imprecision); no serious adverse events were reported after 4 weeks (1 RCT; 27 participants; very low-certainty evidence, downgraded due to methodological limitations and imprecision). CPAP versus sham CPAP One RCT assessed this comparison (61 participants), but we were unable to extract outcomes for this comparison due to the factorial design and reporting of this trial. CPAP versus sildenafil (phosphodiesterase type 5 inhibitors) Sildenafil may slightly improve erectile function at 12 weeks when compared to CPAP, measured with the IIEF-ED (MD -4.78, 95% CI -6.98 to -2.58; 3 RCTs; 152 participants; I² = 59%; low-certainty evidence, downgraded due to methodological limitations). There is uncertainty about the effect of CPAP on sex-related quality of life after 12 weeks, measured with the Erectile Dysfunction Inventory of Treatment Satisfaction questionnaire (EDITS, higher = better; MD -1.24, 95% CI -1.80 to -0.67; 2 RCTs; 122 participants; I² = 0%; very low-certainty evidence, downgraded due to methodological limitations). No serious adverse events were reported for either group (2 RCTs; 70 participants; very low-certainty evidence, downgraded due to methodological limitations and imprecision). There is uncertainty about the effects of CPAP when compared to sildenafil for the incidence of minor adverse events (RR 1.33, 95% CI 0.34 to 5.21; 1 RCT; 40 participants; very low-certainty evidence, downgraded due to methodological limitations and imprecision). The confidence interval was wide and neither a significant increase nor reduction in the risk of minor adverse events can be ruled out with the use of CPAP (4/20 men complained of nasal dryness in the CPAP group, and 3/20 men complained of transient flushing and mild headache in the sildenafil group).

AUTHORS' CONCLUSIONS

When compared with no CPAP, we are uncertain about the effectiveness and acceptability of CPAP for improving erectile dysfunction in men with obstructive sleep apnoea. When compared with sildenafil, there is some evidence that sildenafil may slightly improve erectile function at 12 weeks.

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.

Nonarteritic anterior ischaemic optic neuropathy and its association with obstructive sleep apnoea: a health insurance database study

BACKGROUND

Nonarteritic anterior ischaemic optic neuropathy (NAION) is the most common acute optic neuropathy in old age. Although there are several known risk factors, the influence of obstructive sleep apnoea (OSA) has not been completely elucidated. The aim of this study was to evaluate the association between NAION and OSA.

METHODS

This retrospective, longitudinal cohort study used the national health insurance database of Taiwan covering the period 1996-2013. Patients without NAION at the diagnosis of OSA or who developed NAION 1 year after the diagnosis of OSA were enrolled. The patients were followed until death or the last day of the study. Cox proportional hazard regression was used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) to investigate the association between OSA and NAION.

RESULTS

There were 8488 patients in the OSA group and 33 952 in the control group (without OSA), for a ratio of approximately 1:4. The percentages of NAION were 0.36% and 0.2% in the OSA and control groups, respectively, with a statistically significant difference (p < 0.01; chi-square test), and this significant difference remained in multivariate analysis (p = 0.019) with a significantly higher HR (1.66; 95% CI: 1.08-2.55). There was significant difference in the 30-39 years age group in multivariate analysis (p < 0.01, HR: 6.30; 95% CI: 2.28-17.40).

CONCLUSION

There was a strong association between NAION and OSA, and the patients with OSA had a higher risk of NAION. Further large-scale, prospective studies are warranted to evaluate the effect of OSA on developing NAION.

Erectile Dysfunction Agents and Nonarteritic Anterior Ischemic Optic Neuropathy

Phosphodiesterase-5 inhibitors (PDE5I) are used for treatment of erectile dysfunction and pulmonary arterial hypertension and have been implicated as a causative factor for development of nonarteritic anterior ischemic optic neuropathy (NAION). Controversy remains regarding a cause and effect between PDE5I use and NAION because the mechanism by which NAION occurs is still not well understood. Because neuro-ophthalmologists have accepted that there is a potential relationship between ingestion of the PDE5I class of medications and NAION, the neuro-ophthalmologist should inquire about PDE5I use when evaluating a patient with a new diagnosis of NAION, and counsel patients regarding the implication of continued use of PDE5I.

Small Compartment Toxicity: CN VIII and Quality of Life: Hearing Loss, Tinnitus, and Balance Disorders

Life experiences, industrial/environmental exposures, and administration of Food and Drug Administration (FDA)-approved drugs may have unintended but detrimental effects on peripheral and central auditory pathways. Most relevant to the readership of this journal is the role that drug treatments approved by the FDA as safe and effective appear to interact with 3 independent modes of toxicity within the small compartment of the ear. What may seem to be trivial drug-induced toxicity has the potential to change important measures of quality of life and functional capacity of mid- to late-life patients. Drugs meant to treat can become the source of interference in the activities of daily living, and as a result, treatment compliance may be jeopardized. Ototoxicity has been defined as the tendency of certain therapeutic agents and other chemical substances to cause functional impairments and cellular degeneration of the tissues of the inner ear resulting in hearing loss. However, one of the largest contributors to hospitalizations is fall-related injuries in the elderly patients associated with disorders of vestibular function linked to progressive and drug-induced toxicities. Tinnitus affects 35 to 50 million adults representing approximately 25% of the US population, with 12 million seeking medical care and 2 to 3 million reporting symptoms that were severely debilitating. This review is intended to highlight these targets of neurotoxicity that threaten the usefulness of drug treatments deemed safe and effective prior to access by the general public.

A Case Report: Consecutive Cranial Neuropathies Following the Use of Phosphodiesterase-5 Inhibitors

We report a patient who suffered consecutive cranial neuropathies where each event was immediately preceded by the use of oral PDE-5 inhibitors. A discussion of the etiology of the events including possible interaction with other medications is included.

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.

Identification of a new selective dopamine D4 receptor ligand

The dopamine D4 receptor has been shown to play key roles in certain CNS pathologies including addiction to cigarette smoking. Thus, selective D4 ligands may be useful in treating some of these conditions. Previous studies in our laboratory have indicated that the piperazine analog of haloperidol exhibits selective and increased affinity to the DAD4 receptor subtype, in comparison to its piperidine analog. This led to further exploration of the piperazine moiety to identify new agents that are selective at the D4 receptor. Compound 27 (KiD4=0.84 nM) was the most potent of the compounds tested. However, it only had moderate selectivity for the D4 receptor. Compound 28 (KiD4=3.9 nM) while not as potent, was more discriminatory for the D4 receptor subtype. In fact, compound 28 has little or no binding affinity to any of the other four DA receptor subtypes. In addition, of the 23 CNS receptors evaluated, only two, 5HT1AR and 5HT2BR, have binding affinity constants better than 100 nM (Ki <100 nM). Compound 28 is a potentially useful D4-selective ligand for probing disease treatments involving the D4 receptor, such as assisting smoking cessation, reversing cognitive deficits in schizophrenia and treating erectile dysfunction. Thus, further optimization, functional characterization and evaluation in animal models may be warranted.