It’s easy to dismiss brief vision changes as just “one of those things” in the body, especially if they don’t hurt or seem to go away quickly.
But eye specialists say some of these seemingly small shifts can be early clues of much bigger issues. And often, time is of the essence for seeking treatment and preventing worse outcomes.
To help people better recognize these signs, HuffPost asked eye health experts to share the symptoms they always take seriously and why you shouldn’t ignore them either.
Sudden Flashes Of Light Or A Shower Of New Floaters
“If someone suddenly sees flashing lights or a burst of new floaters, that can be a warning sign for something serious, as it can be the first sign of a retinal tear,” Dr. Avnish Deobhakta, a vitreoretinal surgeon at New York Eye and Ear Infirmary of Mount Sinai, told HuffPost. “The retina has no pain sensors, so these visual changes are the only warning before a possible retinal detachment.”
He described a burst of new floaters with flashing lines as the retina’s “version of a fire alarm” so immediate action is important.
“A floater is a kind of spot in your vision, like a fly or gnat you keep swatting but it doesn’t go away,” said Dr. Randy McLaughlin, an optometrist and associate clinical professor of ophthalmology and visual sciences at the Ohio State Wexner Medical Center. “Patients I’ve seen with retinal detachments describe 20-30 or 40-50 floaters, like a spider web, tree branch or lightning bolt that does not go away.”
Although most floaters are not serious, the sudden onset of a large number of them may indicate a bigger problem. Seeking immediate treatment can help prevent permanent vision loss.
“Getting evaluated via dilated eye exam as soon as possible allows for early treatment and can lead to the best visual outcomes,” said Dr. Ella Faktorovich, an eye doctor and founder of Pacific Vision Institute.
A Dark Curtain Moving Across The Vision
“‘Curtain falling over vision’ can be a sign of a retinal detachment or tear,” Faktorovich said.
She noted that this change can occur on its own or accompany a sudden increase in floaters along with flashes of light or dimming of vision.
“A ‘shadow’ or ‘curtain’ drifting across part of the visual field is one of the biggest red flags in my field,” Deobhakta said. “In addition to other serious ocular issues, it can mean the retina is detaching. That is a true emergency in ophthalmology where hours sometimes matter.”
So if you experience this symptom, seek evaluation by a doctor immediately.
Eye Pain With Redness And Light Sensitivity
“Painful, red eyes ― especially when bright light makes the discomfort worse ― can indicate inflammation, high pressure in the eye or even an infection,” Deobhakta said. “These are not situations to ‘wait and see.’”
He emphasized that some of these conditions can harm your vision quickly if they’re not treated right away.
“Severe pain, redness, light sensitivity or vision loss in a contact lens wearer can indicate serious infection and usually requires immediate treatment with antibiotics to prevent vision loss,” Faktorovich echoed.
Pay attention if that eye pain and redness come with blurred vision as well.
“Severe pain and redness of eye with very blurry vision in one eye can be indicative of an acute glaucoma attack,” said Dr. Douglas Lazzaro, a professor of ophthalmology at NYU Langone Health. “This is a true ophthalmic emergency and must be handled within hours.”
Sudden Loss Of Vision, Even If It Comes Back Quickly
“Transient vision loss is never something to brush aside,” Deobhakta emphasized. “Even if vision returns after a minute or two, that episode can signal a temporary blockage in blood flow to the eye. In effect, this kind of sudden vision loss is often the eye’s version of a stroke.”
He added that this is sometimes the first clue that someone is at risk of another stroke somewhere else in the brain, so seeking medical attention quickly is crucial.
“Temporary loss of vision in one eye for seconds or minutes, as if a curtain was pulled down, is known as amaurosis fugax and can be indicative of an impending stroke,” Lazzaro said. “This would be most common in an individual that has high blood pressure or diabetes, or has been dealing with high cholesterol problems.”
He added that this can be a sign of heart disease or carotid artery plaques as well.
“If somebody says they suddenly lost their vision, especially when it’s painless, that’s when we as doctors have a reason to worry,” said Dr. James Kelly, an ophthalmologist and founder of Kelly Vision. “Usually, when this happens, the patient is experiencing a stroke of the eye, and it’s most common in older people.”
The name for this kind of eye emergency is a central retinal artery occlusion, or CRAO, which basically means a blockage in the artery that supplies blood to the retina. It almost always affects just one eye, but on rare occasions can impact both.
“If you don’t get treated within the first two or three hours when CRAO occurs, you basically go blind, and unfortunately it is irreversible,” Kelly said. “This is a stroke of the eye just like you’d have a stroke of the brain or a heart attack. When this occurs, one of your blood vessels that acts as your central supply chain to the center of the eye gets occluded and the blood can’t flow. When blood can’t flow, essentially the retina dies and therefore your eye no longer functions.”
Sudden Vision Loss In One Eye, Accompanied By Other Symptoms
Faktorovich similarly advised paying attention to any “sudden painless loss of vision in one eye, accompanied with loss of visual field, jaw pain, scalp tenderness, headache or fever/malaise.”
“This can be a sign a of optic neuritis which is decreased perfusion to the optic nerve, which can cause long term damage to the nerve cells, resulting in permanent vision loss,” she explained. “If accompanied by jaw pain, scalp tenderness, headache or fever/malaise, it can indicate giant cell arteritis, which requires immediate treatment with steroids to prevent blindness or permanent vision loss, as well as risk of stroke.”
New Double Vision
“If someone develops new double vision, it is important to determine if it is binocular, which is double vision when both eyes are open, or monocular double vision, which is double vision in one eye,” said Dr. Erin A. Boese, an ophthalmologist with University of Iowa Health Care.
Monocular double vision is typically a sign of less serious conditions like dry eye, astigmatism, cataracts or wrinkling of the retina, she explained. You can determine which is happening by checking if the double vision goes away when you close one eye or the other.
“If it does, then it typically means the eyes are not moving in tandem ― binocular double vision,” Boese said. “While there can be benign causes of this, it can represent a bigger issue with the brain/nerve connections to the eye muscles.”
She pointed to possible causes like cranial nerve palsies, tumors, brain aneurysms and neurological diseases like myasthenia gravis.
“True double vision caused by a cranial nerve palsy or something within the orbit, not a change in glasses prescription, can have many different underlying causes,” said Dr. Cecelia Koetting, an assistant professor of ophthalmology at the University of Colorado School of Medicine. “Longstanding uncontrolled blood sugar and blood pressure are the most common, but other concerning causes could be a brain tumor, mass or lesion or a stroke.”
Straight Lines That Look Wavy Or Distorted
“If a patient tells me that words on a page look bent or that straight edges suddenly appear wavy, that’s something I never ignore,” Deobhakta said. “This kind of distortion usually points to a problem in the macula, which is the part of the eye that gives you sharp central vision.”
He noted that conditions like wet macular degeneration often start this way, and early treatment can make a big difference.
“When straight lines suddenly look wavy, that’s the macula telling you something is wrong and needs to be checked out immediately,” Deobhakta said.
McLaughlin pointed to the value of an eye testing tool called the Amsler grid.
“It’s basically just a grid, but it’s a great test people can use to assess their macular function,” he said. “If those lines are wavy or there’s a spot that’s wavy, that can show a sign of swelling and maybe the person has diabetes ― or if you’re an older person, it could be a sign of the beginning of macro degeneration.”
A Newly Unequal Pupil Or A Droopy Eyelid
“A pupil that suddenly becomes a different size from the other, or a drooping eyelid that appears out of nowhere, can be signs of an underlying nerve or even vascular issue,” Deobhakta said. “These neurological changes might be subtle but can represent something extremely serious such as an aneurysm or stroke. If they occur, it could be the eye telling us something the brain needs us to know and should be evaluated immediately.”
Indeed, you might be referred to a neuro-ophthalmologist for further evaluation.
“A different pupil slide size or one eyelid drooping is a sign of a potential neurologic problem,” McLaughlin echoed. “So you’d want to evaluate for [some] sort of neural issue or even a tumor.”
Chronic Dry Eye Or Itchy Eyelids
“Dry eye isn’t just ‘dry eye,’ and it doesn’t always go away on its own,” Koetting said. “It can cause eye pain, fluctuating vision, itchiness, grittiness and even tearing ― yes, it sounds counterintuitive.”
She noted that dry eye is a multifactorial condition with many causes, symptoms, and treatment options.
“Left untreated long-term, it can lead to corneal nerve damage, poor healing, corneal scarring, and an increased risk of permanent vision loss,” Koetting said.
Similarly, she pointed to persistent itchy eyelids as another symptom that warrants a look from an eye care professional.
“It is allergies, bacteria or is it an overgrowth of Demodex ― a mite that lives in hair follicles and oil glands?” Koetting asked. “We won’t know until we take a closer look, but if it were me, I’d come in to have it checked.”