AION Anterior Ischemic Optic Neuropathy

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AIONAnterior Ischemic Optic Neuropathy

• AION ( anterior ischemic optic neuropathy) is a
  vascular event that is presumed to occur due to a
  decrease in blood flow to the small arteries that
  supply the optic nerve. A disruption in the blood
  supply to the optic nerve causes damage to the
  nerve.
• Injury to the nerve may result in permanent
  visual loss in one or both eyes.
• There are two types arteritic and non-arteritic.
  Arteritic (AION) is an inflammatory vasculitis,
  and nonarteritic (NAION) is a diagnosis of
  exclusion-meaning in the absence of provable
  arteritis.

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NAION incidence

• NAION is the most common acute optic neuropathy
  in the elderly
• Incidence 2.3 to 10.2 per 100,000 for persons
  50 years and older/year.
• New cases/year in the USA 1500 - 6000.
• (Johnson LN, Arnold AC. J Neuro-ophthalmol 14
  (1994), 3844.
• Hattenhauer, MG et al. Am J Ophthalmol 123
  (1997), 103107).
• Follow-up data from the IONDT cohort provide
  evidence that the
• incidence of fellow eye NAION is 14.7/100 of
  IONDT patients
• over approximately 5 years.
• Increased incidence is associated with poor
  baseline visual acuity
• in the study eye and diabetes, but not age, sex,
  smoking history,
• or aspirin use.
• (Newman NJ et alAm J Ophthalmol. 2002
  Sep134(3)317-28).

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NAION conclusions I

• The exact cause of NAION is unknown.
• NAION has occurred in patients between the ages
  of 55 and 70 and those with high blood pressure,
  diabetes, high cholesterol, low blood pressure at
  night, ischemic heart disease, smoking, and an
  anatomical variant in the eye
• NAION is a rare condition with an incidence of 2
  to 10 cases per year per 100,000 persons 50 and
  older.
• The onset is characterized by sudden painless
  visual loss that may progress over hours to weeks

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NAION conclusions II

• The publication by Drs. Pomeranz was a report of
  seven men who developed NAION in association with
  taking Viagra.  
• Their publication stated that the total number of
  reported NAION cases associated with sildenafil
  is 14.
• NAION has been reported in patients taking
  several other medications, specifically,
  sumatriptan (Imitrex - a migraine drug),
  amiodarone (Procor), and nasal decongestants.  
• Today NAION was reported in 38 patients taking
  sildenafil (Viagra), and 4 with tadalafil
  (Cialis), these associations do not necessarily
  mean the drugs caused NAION.

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NAION conclusions III

• There have also been multiple clinical studies
  on the effects of sildenafil on the ocular
  circulation. None of those studies indicated that
  sildenafil or Tadalafil treatment causes a
  decrease in optic nerve head or choroidal blood
  flow.
• Some studies actually suggest small increases in
  ocular blood flow.

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NAION conclusions IV

• A review of 103 Viagra clinical trials involving
  13,000 patients found no reports of NAION.
• Apart from clinical trials, Viagra has been used
  by more than 23 million men worldwide and Cialis
  in more than 4.5 millions.
• NAION has been reported rarely through
  post-marketing surveillance with short and long
  acting PDE5 I and most patients had underlying
  anatomic or vascular risk factors for the
  development of NAION.
• There is no evidence showing that NAION occurred
  more frequently in men taking Viagra or Cialis
  than men of similar age and health who did not
  take these medications.