Vision Changes in Ultra Marathon Runners

Introduction

In an ultramarathon race, that lasts for 24 to 36 hours, many changes happen to the eyes, which can lead to vision changes. Corneal edema is one of the major changes that appear after the race and usually resolves within a few hours. Proper eye protection equipment can help prevent such a situation. Any type of vision change has to be addressed immediately with an ophthalmologist.

What Is an Ultra Marathon?

An ultra-marathon is any race that is longer than the traditional marathon distance of 42.195 kilometers. The shortest distance for the competition is 50 kilometers and can vary up to 321.869 kilometers. The long-duration endurance races help with a regular cardio workout that reduces the risk of heart disease and boosts mental health.

On the other hand, excess exercise can lead to cardiac concerns. Loss of muscle mass and injury should be expected if not done properly. Many runners take 24 to 36 hours to finish the long races.

What Is Ultra Marathon-Induced Corneal Edema (UMICE)?

It is a clinical condition that causes corneal edema due to increased physical exertion. It is a rare, multifactorial phenomenon. The corneal edema usually resolves within a few hours after the ultra-marathon race. It is commonly seen in foot races of more than 422 kilometers. Other sports events that might cause corneal edema are bicycling and cross-country ski ultramarathons.

What Are the Causes of UMICE?

• During marathon races, the corneal epithelium endures wind, temperature changes, and ultraviolet radiation (UV), and decreases oxygen levels at high altitudes.

• Ultramarathon runners constantly use their eyes to select paths and visuals. Attention changes spontaneously. This creates a physical challenge for the cornea.

• The corneal cells try to cope with the environmental stress, and it enhances glycolysis. When the process of glycolysis increases, the production of lactate also increases.

• Corneal edema occurs due to lactate buildup in the corneal epithelium. External factors like wind or sweat cause external corneal stress, which leads to increased lactate production. The increased physical exertion also increases the level of lactate in blood and aqueous humor. Lactate is a metabolite in the corneal metabolism. The elevation of lactate in blood impairs the facilitated transport of lactate into the anterior chamber of the eye. All these factors lead to corneal lactate buildup and corneal edema.

• The higher altitude and exposure to UV lights can also cause corneal edema in ultramarathon runners. High altitude causes hypoxia that can increase the central corneal thickness. Thus, hypoxia-induced corneal edema is also reported in marathon runners.

• The UV-induced oxidative changes affect the corneal cells. Corneal epithelial cells adapt more quickly than other epithelial cells. The mechanism by which the corneal epithelial cells limit the effects of UV radiation involves glycolysis, which helps produce more ATP. UV radiation can damage the pumping mechanism of endothelial cells.

• Dehydration can increase the blood lactate level and aggravate corneal edema.

• Other factors that may cause corneal edema include

  • Wearing soft contact lenses.

  • Alteration in corneal hydration.

  • Prior history of corneal refractive surgery.

What Are the Signs and Symptoms of UMICE?

• Painless blurred vision.

• Vision loss is blurry.

• No photophobia

• Corneal edema.

• Vision resolved spontaneously after 25 to 48 hours of a marathon race.

What Are the Treatments Given for UMICE?

• The prophylactic measure includes the use of lubricant eye drops and protective eyewear.

• If corneal edema is present, stop marathon races; that will help to reverse the symptoms.

• The application of 5 % hypertonic sodium chloride helps to enhance corneal clarity.

• Rest or closing of the eyes is advised.

What Is the Differential Diagnosis of UMICE?

• Neuro Ophthalmological Transient Vision Loss- lasts only for a short time, comes and resolves quickly, causing darkening of vision but not causing corneal edema.

• Uhthoff's Phenomenon in Optic Neuritis - Causes visual disturbances during exercises, and the cornea does not look hazy.

• Pigment Dispersion Syndrome- Elevated intraocular pressure with corneal edema, ocular pain, and intermittent blurred vision.

• Acute Corneal Hydrops- Causes pain, red eyes, and photophobia. It results in a hazy cornea with elevated intraocular pressure.

• Pigment Dispersion Syndrome - Shows symptoms similar to corneal edema. It causes the release of iris pigment during exercise, resulting in increased intraocular pressure and blurred vision.

• Uveitis Glaucoma Hyphema Syndrome - Shows symptoms similar to pigment dispersion syndrome and leads to hemorrhage.

• Contact Lens Irritation - This can differ from UMICE as it is more superficial and causes hypoxic edema, which also causes a burning sensation or pain.

• Eye Dryness - Associated with foreign body sensations or pain. The cornea is not cloudy but causes disturbed vision.

• Corneal Erosion - Spontaneous or nonspontaneous corneal erosion with pain.

• Frozen Cornea -The frozen cornea, or wind blindness, seen in cold climates is a painful condition.

What Are the Complications of UMICE?

The complications include

• Blurred vision can lead to physical injuries.

• Long-term effects on the cornea.

What Is the Prognosis For UMICE?

Patients with a history of corneal edema are advised to use protective eyewear and lubricant eye drops. Corneal edema resolves soon and may recur if participants participate in similar marathon races.

How Does Vision Loss Occur in an Ultramarathon?

Ultramarathon-associated vision loss has been reported in marathon runners, where the symptoms resolve after the cessation of the race. It took an average recovery time of 3.5 hours and completely recovered after 48 hours.

• The cornea appears milky white.

• Self-limited, painless clouding of the cornea.

What Are the Factors Affecting Visual Impairment in Ultramarathons?

• Refractive surgery- participants who had refractive surgery earlier are more likely to have episodes of visual impairment. This may be due to disturbances in the normal functioning of corneal tissue, and accumulation of fluid occurs easily.

• LASIK surgery has been found to interfere with the normal blink reflex and can lead to corneal edema or frozen edema.

• Long races - In long races of about 100 miles or more, participants were reported to have vision impairment.

• Wide range in the ambient temperature.

• Wind.

• Higher altitude.

How to Prevent Vision Changes in an Ultramarathon?

• Use clear glasses that help protect one from debris, bugs, and unseen obstacles.

• If participants are myopic, it is advised to use glasses or contact lenses.

• Wearing sunglasses while running will protect the eyes from harmful UV rays.

• Use glasses that fit the face.

• Use glasses with nose pads.

• Use of a sports strap, to prevent glasses from falling off.

• Use an anti-fog lens.

• Use a sweatband, as it helps reduce the sweat and prevents it from catching the glasses.

• Proper cleaning of glasses after running.

• Use of transition lenses.

• Use of anti-glare lenses.

• Prefer to use a hat or visor with the glasses.

• Use glasses designed for sports activities.

Conclusion

Ultramarathon-induced vision changes are rare and multifactorial conditions. The factors like debris, dust, wind, temperature, the long duration of the race, and a lack of protective eyewear can cause vision changes. The vision changes can be prevented by taking adequate eye protection measures. The participants must be educated about health issues and the proper preventive methods before heading to an ultramarathon race.