Bilateral Sequential Non-arteritic Anterior Ischemic Optic Neuropathy (NAION)

Changes in Posterior Ocular Structures in Individuals Using Phosphodiesterase 5 Inhibitor

PURPOSE

To examine posterior ocular structures with optical coherence tomography (OCT) in individuals using a phosphodiesterase 5 inhibitor (PDI, tadalafil).

METHOD

This prospective study included 26 eyes of 26 patients who used 1 tablet of 5-mg tadalafil regularly every day for 1 month due to erectile dysfunction. The routine ophthalmological examinations of the participants were performed at the pre-tadalafil and post-tadalafil first-month visits. At both visits, OCT was used to measure the central retinal thickness (CRT), ganglion cell layer + inner plexiform layer (GCL + IPL) thicknesses, and peripapillary retinal nerve fiber layer (pRNFL; average and superior, temporal, inferior, and nasal quadrants) thicknesses. The disc area, rim area, average and vertical cup/disc ratio, and cup volume of the optic disc head were evaluated. Choroidal thickness was measured from five points: the subfoveal area and the nasal and temporal areas 500 and 1500 microns from the fovea. Choroidal vascular area values and choroidal vascular index (CVI) were calculated using a special binarization technique.

RESULTS

The mean age of the patients was 56 ± 8(range 34-72) years. No significant difference was detected in the CRT,GCL + IPL thicknesses,or pRNFL thicknesses in any of the quadrants before and after tadalafil use.The optic disc head measurements and choroidal thickness values measured from five points were similar between the two visits.The luminal choroidal area was 0.15 ± 0.04 mm2 before tadalafil use and 0.17 ± 0.05 mm2 after 1-month tadalafil use, with no statistically significant difference. The remaining choroidal vascular parameters, namely the stromal and total choroidal area and CVI values, were similar between the two visits.

CONCLUSION

This study showed no significant change in the posterior ocular structures in individuals using tadalafil regular daily use for 1 month due to erectile dysfunction.

Binasal Field Defect in Non-arteritic Anterior Ischemic Optic Neuropathy

Non-arteritic anterior ischemic optic neuropathy (NAION) is the most common cause of optic neuropathy in older adults and is usually associated with an altitudinal visual field defect. Binasal hemianopia is a rare visual field presentation, and most causes are due to ocular pathology instead of brain pathology. It is an infrequent finding in NAION. We report a rare presentation of binasal hemianopia visual field defect in a patient with NAION. This a case of an elderly lady with underlying uncontrolled type 2 diabetes mellitus, hypertension, and dyslipidemia who presented with a sudden onset of painless blurring of vision in the left eye. She had a similar episode of blurred vision involving the other eye two years ago. Her visual acuity was reduced in both eyes. Humphrey visual field showed a binasal field defect. Fundoscopy showed mild hyperemic optic disc swelling in the left eye and a pale disc in the right eye. The CT scan and MRI were normal. She was co-managed with the medical team to control her systemic risk factors. Although NAION is the most common cause of optic neuropathy in older adults, binasal hemianopia is a rare visual field presentation in NAION. The history and assessment from this case add important information toward diagnosing NAION.

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.