PREVENTIVE MEASURES

Prevention of a NAION event is a bit of a misnomer. NAION, like so many diseases, is a condition that is challenging, at best, to prevent entirely, however, there are steps that can be taken that may reduce the risk. Knowledge of the risk factors is a must.

Non-modifiable Risk Factor

Disc-to-cup:

One of the risk factors is known as the disc-to-cup ratio. It is also known as “disc-at-risk” and “crowded disc.” A small disc is an “architectural” abnormality that predisposes one to an event. In simplest terms, the disc-to-cup is the opening through which blood and oxygen are supplied to the optic nerve. It is also referred to as a “crowded disc” and is smaller than normal. There is a more likely possibility that anything from a clot (eye stroke) to pinching off of the blood supply from inflammation may occur.

Often both eyes will have the same disc-to-cup ratio meaning it is possible, though unlikely, that a second NAION event may cause vision loss in the other eye. Not to minimize the chances of having a second event but the odds of having a single NAION event are incredibly small to begin with. Though the odds are set at 15-25% of having another event, it may stand to reason that they are very small odds behind an already extremely remote chance that one would have a first event. I would like to kow what criteria was used to come up with these odds. Of course with the knowledge of having a first event,  one can take steps to further reduce the odds. 

Keep in mind that the architecture of the disc-to-cup is what it is. In other words it can’t be modified or changed. The only way one would know if they have a “disc-at-risk” or “crowded disc” is if a test were to be performed by an Opthalmologist or retinal specialist. Who would ever think to ask for such a test in advance.

Another thing about disc/cup, it may be a genetic issue and may be hereditary. 

Another non-modifiable risk factor is age. NAION presents mainly in people over the age of 50. However, the odds of some other eye disease, or other medical malady are far greater than a NAION event.

 About modifiable risks:

Modifiable risk factors are those factors we have some influence or control over. Taking the necessary steps to bring them into healthy alignment or elimination of use may help minimize negative impact of a NAION event.

Modifiable risk factors include:

  • Hypertension- High blood pressure. Medication may be prescribed but it’s been strongly recommended to take in the morning rather than evening.
  • Diabetes- Damages arterial walls. Besides diabetes havig a physisiological affect that could contribute to NAION, there are a couple of new drugs on the market that have been linked to triggering a NAION event, namely Ozempic and Mounjaro. Link to more info: https://www.reviewofoptometry.com/news/article/risk-of-naion-higher-in-patients-on-glp1-drugs-for-diabetes-or-weight-loss
  • Sleep apnea-“The visually devastating condition of NAION is strongly associated with OSA… Approximately 70-80% of patients with NAION have been diagnosed with OSA and those with NAION are five times more likely to have OSA.” see https://www.restorevisionclinic.com/blog/sleep-apnea-is-a-risk-for-optic-nerve-damage      
  • Hyperlipidemia (High cholestral; the presence of excess fat or lipids in the blood)
  • Smoking
  • Use of certain medications (e.g., PDE5 inhibitors like Viagra & Cialis)
  • Unpressurized altitude (somewhat controversial above 7,000 ft.)
  • Anesthesia medications that effect blood pressure or have effects with other medications or comorbidities. When scheduling surgery, you want to be very clear with you doctor and the anesthesiologist that they understand your condition regarding NAION. The surgeries include the more mundane as in dental work through open heart.

How can you modify and regulate these risk factors to help reduce the chances of more NAION events? In a few words, diet, exercise and the appropriate medication as prescribed by your health care provider.

There are other factors that are either controversial or too much to include here. They include, but are not limited to:

Altitude- It is accepted that unpressurized altitudes above 7,000 ft may affect or trigger a NAION event. Always consult with your ophthalmologist regarding air travel and/or climbing.

Anesthesia medications that effect blood pressure or have effects with other medications or comorbidities. When scheduling surgery, you want to be very clear with you doctor and the anesthesiologist that they understand your condition regarding NAION. The surgeries include the more mundane as in dental work through open heart.