Many eye diseases begin without pain or obvious loss of sight. People often delay seeking help because they can still read, drive, or work normally. That is when the damage is easiest to prevent but hardest to notice. On this World Sight Day, it is worth remembering that more than two billion people worldwide live with vision impairment, and at least half of these cases could have been avoided through early examination.

Below are seven symptoms that should never be ignored, even when vision appears normal.

1. Flashes or Floaters That Appear Suddenly

Small moving spots or threads in vision are common as people age. They form when the gel inside the eye separates naturally from the retina. When new floaters appear abruptly, especially with flashes of light or a curtain-like shadow, it can mean a retinal tear or detachment. This is an emergency that needs prompt treatment to prevent permanent loss of sight. Detachments affect roughly 10–20 individuals per 100,000 each year, most often after middle age or following injury.

2. Halos Around Lights

Rings or coloured halos around lights may occur in early cataract or with swelling of the cornea. If halos appear suddenly with headache, nausea, or eye pain, the likely cause is acute angle-closure glaucoma. India has more than 12 million people living with glaucoma, making it the second leading cause of blindness after cataract. Sudden halos should be treated as a red flag, not a passing irritation.

3. Persistent Dryness or Gritty Sensation

Dry eye disease is now one of the most common complaints in urban clinics. Studies show that almost one in three urban Indians experience dryness linked to screen time, air-conditioning, or pollution. It usually causes discomfort, but severe or persistent dryness can damage the cornea and blur vision. In some people, it is also the first sign of autoimmune illness. Artificial tears provide temporary relief, but a specialist can assess tear film quality and gland function to address the cause.

4. Eye Pain or Pressure

A sense of pressure, ache, or fullness behind the eyes may come from raised intraocular pressure, inflammation (uveitis), or acute glaucoma. Some infections, sinus disease, or migraine can also cause similar pain, but persistent or recurrent discomfort needs examination. Pain that worsens with light or movement of the eye should be considered serious until proven otherwise.

5. Sensitivity to Light

Excessive light sensitivity, called photophobia, may accompany corneal infection, uveitis, or certain viral inflammations such as herpes simplex keratitis. Because these conditions can progress rapidly, they should be evaluated early. Repeated episodes of light sensitivity are sometimes related to chronic inflammation that quietly damages internal eye structures over time.

6. Double Vision

Double vision can arise from temporary fatigue, but constant or sudden onset diplopia is usually neurological or muscular in origin. It can indicate cranial nerve palsy, thyroid eye disease, or occasionally a mini-stroke. In people with diabetes, nerve palsy affecting eye movement is a known complication. Persistent double vision warrants neurological and ophthalmic assessment rather than waiting for spontaneous improvement.

7. Blurred or Distorted Vision in One Eye

If straight lines appear bent, or if part of the central vision fades, the macula may be affected. Causes include age-related macular degeneration or swelling from diabetic retinopathy. India’s 77 million people with diabetes face a significant risk of retinal disease; yet, many undergo screening only after vision is impaired. Annual retinal imaging for all adults with diabetes remains one of the simplest ways to prevent irreversible blindness.

The Takeaway

Most vision-threatening eye diseases develop quietly. The absence of pain or early visual loss does not mean the eye is healthy. Regular eye examinations—particularly after forty years of age or in people with diabetes, hypertension, or a family history of glaucoma—are essential preventive care.

Sight once lost cannot always be restored, but almost every serious eye disease gives some early warning. Recognising it is the first act of preservation.

(The writer is a MS, DO, Consultant Ophthalmologist, Apollo Hospitals, Visakhapatnam)