Head of the Ophthalmology Department, Consultant Ophthalmic Surgeon of the Highest Category, MD, PhD Jamshid Furkatovich Mamatov on eye diseases that can remain symptom-free for years, warning signs that should never be ignored, and mistakes that may cost a person their vision.

We tend to assume that everything is fine with our eyes as long as we can see well. There is no pain, we can read text on our phones, recognize faces — so there seems to be no urgent reason to visit an ophthalmologist.

But that is precisely where one of the major problems lies. According to the World Health Organization, at least 2.2 billion people worldwide live with near or distance vision impairment. Of these, at least 1 billion cases could have been prevented or remain amenable to correction. The leading causes of vision impairment worldwide include uncorrected refractive errors, cataract, glaucoma and diabetic retinopathy. The problem is not limited to the diseases themselves. Many people postpone an eye examination until their vision has already begun to deteriorate noticeably.

Can a person see well and still have a serious eye disease? Why can glaucoma remain unnoticed for years? Does using a phone really damage eyesight? Should people wait for a cataract to “mature”? And which symptoms mean that an ophthalmologist should be consulted not tomorrow, but today?

We discussed these and other questions with ophthalmologist Dr. Jamshid Furkatovich Mamatov.

— Dr. Mamatov, can a person have an eye disease that is gradually threatening their vision while still seeing well?

Yes, and that is the main danger. Many diseases do not initially affect visual acuity — the ability to distinguish fine details in the center of vision.

Peripheral vision, contrast sensitivity or retinal blood vessels may be affected first. The brain compensates for some of these changes, while the second eye may partially compensate for a defect in the first.

• Glaucoma — peripheral vision is affected first.
• Diabetic and hypertensive retinopathy — retinal vascular changes are often painless.
• Early cataract and age-related macular degeneration — people may gradually adapt to the changes.

Epidemiological studies suggest that approximately half of people with glaucoma are unaware of their diagnosis. In areas where access to ophthalmic care is limited, the proportion may be as high as 90%.

— What is glaucoma? Why can it develop for years almost unnoticed, and can vision already lost because of glaucoma be restored?

Glaucoma is a chronic disease of the optic nerve in which nerve fibers gradually die and the visual field becomes progressively narrower. The main modifiable risk factor is elevated intraocular pressure (IOP).

Why is it often unnoticed? There may be no pain, vision loss usually begins in the periphery, and central vision can remain relatively preserved until the later stages. The brain and the other eye can also mask the defects.

By the time symptoms become noticeable, a significant portion of the visual field may already have been lost. Lost vision cannot be restored, because damaged optic nerve fibers do not regenerate. Treatment — including eye drops, laser procedures or surgery — has one main goal: to stop or slow disease progression. Clinical studies have shown that each 1 mmHg reduction in IOP is associated with approximately a 10% reduction in the risk of glaucoma progression. This is why early diagnosis is so important. Risk factors include: age over 40, glaucoma in parents or siblings, myopia, diabetes and long-term use of corticosteroid medications. Close relatives of people with glaucoma should undergo an eye examination.

— If intraocular pressure is within the normal range, can a person be sure they do not have glaucoma?

No. Normal-tension glaucoma exists, and it accounts for a significant proportion of open-angle glaucoma in some Asian populations, including Japan, Korea and China. In addition, IOP fluctuates throughout the day, while corneal thickness can affect measurement results. Diagnosis is based on a combination of findings, including optic nerve head examination, OCT (optical coherence tomography), visual-field testing, gonioscopy, pachymetry and follow-up over time.

The opposite situation can also occur: elevated IOP without optic nerve damage, known as ocular hypertension. Such patients require monitoring but do not necessarily require treatment.

— If someone wakes up and suddenly notices that vision in one eye has become worse, can they wait a few days?

No. They should seek medical attention the same day, ideally within hours. Sudden loss or significant reduction of vision should be considered an emergency until proven otherwise.

• Retinal artery occlusion — essentially an “eye stroke.” The retina can tolerate a lack of blood flow for only a limited number of hours. The American Heart Association recommends managing such patients as stroke patients.
• Retinal vein occlusion, retinal detachment, vitreous hemorrhage, acute glaucoma, optic neuritis and ischemic optic neuropathy can also cause sudden visual loss.
• In people over 50 with headache and pain while chewing, giant cell arteritis should be considered. Without urgent corticosteroid treatment, the second eye may also be lost.

Do not use eye drops on your own and do not wait for the problem to “go away.” Sudden visual loss may also signal a major vascular event, including a TIA or stroke, so cardiovascular risk should be assessed after the ophthalmic examination.

— How dangerous are sudden flashes, “lightning,” numerous black spots or the sensation of a dark curtain appearing from the side?

They can be very serious. These may be signs of a retinal tear or retinal detachment, and an examination is required within 24 hours. With age, and earlier in people with myopia, the vitreous body can detach from the retina and exert traction on it. This may cause flashes of light. Blood or pigment can appear as numerous dark spots, while a “curtain” may indicate that the retina is already detaching. According to clinical recommendations, retinal tears are found in approximately 10–15% of patients presenting with acute posterior vitreous detachment. A retinal tear can often be sealed with laser treatment in an outpatient setting within minutes, preventing retinal detachment. Retinal detachment requires surgery, and the earlier it is treated — particularly before the central retina is affected — the better the outcome. The risk is higher in people with high myopia, previous eye trauma or previous cataract surgery.

— When are ordinary “floaters” relatively harmless, and when can they indicate serious retinal disease?

Usually less concerning: floaters that have been present for a long time, remain stable, are few in number, and are not accompanied by flashes, shadows or reduced vision. Warning signs: sudden onset, a significant increase in number, a “rain” or “soot-like” appearance, flashes, shadows or a curtain, reduced vision, onset after trauma or surgery, inflammation, or the presence of diabetes. Any new floaters require a dilated fundus examination. Even if no retinal tear is found, a repeat examination after several weeks may be recommended because a retinal tear can develop later.

— Do phones and computers actually damage eyesight, or is the main issue how long and at what distance we use them?

The problem is primarily related to viewing time and distance, not the screen itself. Screens do not cause retinal disease or permanently “ruin” eyesight in adults.

However, during prolonged near work, people blink less frequently, which can lead to digital eye strain — dryness, burning, fatigue and headaches. There is currently no convincing evidence that blue light from screens damages the retina. A 2023 Cochrane review did not find a clear benefit of blue-light-filtering glasses for reducing visual fatigue, and the American Academy of Ophthalmology does not recommend them for this purpose.

• Keep the monitor approximately an arm's length away.
• Keep the phone at least 30–40 cm from your eyes.
• Take a short break every 20 minutes and look into the distance.
• Make a conscious effort to blink more frequently.
• If the eyes are dry, preservative-free lubricating drops may be used.
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— Can frequent smartphone and tablet use increase the risk of myopia in children, and what role does outdoor time play?

Yes, there is an association, and outdoor time is an important protective factor. Myopia is spreading rapidly. Projections suggest that by 2050, approximately half of the world's population may be affected by myopia. Prolonged near work, including smartphone use, has been associated with a higher risk of myopia. Daylight exposure and looking into the distance are protective. Randomized studies in schoolchildren have shown that additional outdoor time can reduce the incidence of new-onset myopia. The International Myopia Institute recommends approximately two hours outdoors per day. At the same time, children should be protected from excessive ultraviolet exposure with appropriate clothing and UV-protective sunglasses. According to WHO recommendations, screen use is not recommended for children under two years of age, while for children aged 2–4 years it should generally be limited to no more than one hour per day.

When myopia is already present, its progression may be slowed using low-dose atropine, orthokeratology, specially designed spectacles and myopia-control soft contact lenses. These options should be selected by an ophthalmologist.

— If a child starts squinting, sitting closer to the television or holding a phone very close to their face, how seriously should parents take these signs?

Seriously. The child should undergo an eye examination within the next few weeks rather than waiting for a routine school screening.

Children rarely complain because they do not know how other people see. Possible causes include myopia, hyperopia, astigmatism, strabismus and amblyopia (“lazy eye”). Children should have their refraction assessed under cycloplegia, meaning after pupil dilation, because otherwise the measurement may be inaccurate. Amblyopia is most effectively treated before approximately 7–8 years of age; the effectiveness of treatment decreases later.

— Is it true that if you start wearing glasses all the time, your eyes become “dependent” on them and your vision gets worse?

No. This is a myth. Glasses do not weaken the eyes. Myopia is related to the elongation of the eyeball and progresses independently of whether a person wears glasses. The feeling that vision has become worse without glasses usually occurs because we become accustomed to seeing a sharp image. Under-correction does not slow myopia progression. In children, appropriate glasses are important for normal visual development; without them, amblyopia may develop.

— Can eye exercises actually reduce myopia or eliminate the “minus” prescription?

No. This is another myth. Eye exercises cannot reverse the anatomical changes responsible for myopia or eliminate the refractive error. The appropriate approach is accurate optical correction and, where necessary, evidence-based myopia-control treatment under an ophthalmologist's supervision.

— Can vitamins, lutein, blueberries or various supplements genuinely improve vision?

Most such claims are exaggerated. No dietary supplement restores normal vision or replaces glasses.

• One evidence-based formulation is AREDS2, which can reduce the risk of progression from intermediate to advanced age-related macular degeneration by approximately 25%. It is intended for people with the appropriate diagnosis and should be recommended by a physician.
• Supplements have not been shown to prevent macular degeneration or cataract in healthy individuals.
• There is no convincing evidence that blueberries improve vision.
• Omega-3 fatty acids did not demonstrate benefit for dry eye in the large DREAM trial.

Lifestyle measures that genuinely matter include not smoking, controlling blood pressure and blood glucose, protecting the eyes from UV radiation, and maintaining a diet rich in vegetables — particularly green leafy vegetables — and fish.

— How safe is it to buy over-the-counter “redness relief” eye drops and use them regularly without consulting an ophthalmologist?

It is not considered safe. Many such drops contain vasoconstrictors. They provide temporary relief but may cause rebound redness and dependence with regular use. In susceptible individuals, they may also trigger an acute angle-closure glaucoma attack. The main problem is that these drops can mask the underlying cause of redness, such as allergy, dry eye, inflammation, keratitis or glaucoma. A red eye accompanied by pain, photophobia or reduced vision requires an examination rather than self-medication. Self-use of steroid eye drops such as dexamethasone is particularly dangerous because they can cause glaucoma and cataract and may worsen herpetic keratitis.

— If someone constantly experiences dryness, burning and a gritty sensation, are artificial tears enough?

They may be sufficient for mild cases, but persistent symptoms require evaluation of the underlying cause.

Dry eye disease is multifactorial. Possible underlying causes include meibomian gland dysfunction, blepharitis, allergy, Sjögren syndrome and other systemic diseases, medication side effects, contact-lens-related problems and incomplete eyelid closure. Treatment may include preservative-free lubricating drops, eyelid hygiene, warm compresses and modification of environmental factors such as air conditioning, dry air, dust and prolonged screen exposure.

If symptoms persist for more than two weeks, or if there is pain, photophobia or reduced vision, medical evaluation is recommended.

— How dangerous is it to occasionally sleep in contact lenses or wear them longer than recommended?

It is dangerous, and even occasional overnight wear carries a risk.

Sleeping in contact lenses increases the risk of microbial keratitis, including corneal ulcers. Reduced oxygen availability and easier bacterial penetration can result in serious infection.

A corneal ulcer may lead to corneal scarring, permanent vision loss and, in severe cases, the need for corneal transplantation.

• Replace lenses according to the recommended schedule.
• Replace the lens case every three months.
• Daily disposable lenses are among the safest options.
• Never wash or store contact lenses in water.
• Do not swim or shower while wearing them.
• If redness, pain or photophobia develops, remove the lenses and seek medical attention the same day.

— Should people still wait for a cataract to “mature,” or is that approach outdated?

That approach is outdated. In the past, cataract surgery was more traumatic, so doctors often waited until the cataract became “mature.” Modern phacoemulsification with intraocular lens implantation is a minimally invasive procedure that usually takes approximately 15–20 minutes under local anesthesia. According to modern ophthalmic recommendations, the indication for surgery is vision loss that interferes with daily life — working, reading, driving or moving around safely. There is no need to wait for the cataract to become “mature.” Surgery may also be performed earlier for medical reasons, such as the risk of angle-closure glaucoma or the need to examine and treat the retina in patients with diabetes.

— Can delaying cataract surgery for too long make subsequent treatment more difficult?

Yes. A hypermature cataract becomes denser and more difficult to remove, while the risk of complications and corneal damage increases.

In addition:

• secondary glaucoma and inflammation may develop because of a swollen or degenerating lens;
• the opaque lens can make examination and treatment of the retina more difficult, particularly in patients with diabetes;
• poor vision increases the risk of falls and fractures in older adults.

Unfortunately, some patients present with very advanced, dense cataracts, making both surgery and recovery more difficult.

— Is laser vision correction suitable for almost everyone nowadays?

No. It is not suitable for everyone.

The decision should be made after a comprehensive eye examination, including corneal topography and tomography.

Important contraindications and limitations include:

• age below 18, and usually below 21, or unstable refraction during the previous year;
• thin cornea, keratoconus or suspected keratoconus;
• severe dry eye disease;
• ocular inflammation;
• glaucoma;
• significant cataract;
• uncontrolled systemic diseases such as diabetes or autoimmune disorders;
• pregnancy and breastfeeding;
• very high degrees of myopia, where other options, such as phakic intraocular lenses, may be considered.

Laser vision correction does not eliminate age-related presbyopia. After approximately 40–45 years of age, reading glasses may still be needed.

— Can an ophthalmologist identify signs of diabetes, hypertension or other systemic diseases during a routine eye examination?

Yes. The retina is one of the few places in the body where blood vessels and neural tissue can be directly observed without an incision. A fundus examination can sometimes be the first step toward identifying an underlying systemic disease.

• Diabetes: microaneurysms, retinal hemorrhages and exudates.
• Hypertension: narrowing of retinal arterioles, hemorrhages and, in severe cases, optic disc swelling.
• Other conditions: emboli associated with carotid artery stenosis, increased intracranial pressure, autoimmune and infectious uveitis, optic neuritis associated with multiple sclerosis, thyroid disorders and lipid metabolism abnormalities.

— Which eye symptoms do you consider genuine “red flags” that should never wait for a routine appointment?

In short: any sudden change in vision, eye pain or eye trauma should be treated as urgent.

Same-day emergency assessment:

• sudden loss or marked reduction of vision in one or both eyes;
• flashes, a sudden shower of floaters, a shadow or curtain in the visual field;
• severe eye pain with redness, nausea, headache and halos around lights — possible acute glaucoma;
• chemical injury — immediately rinse the eye with water for 15–20 minutes and then seek medical care;
• eye trauma or penetrating injury;
• a painful, red, light-sensitive eye, particularly in a contact lens wearer;
• sudden double vision, drooping eyelid or unequal pupils;
• a white pupil or sudden strabismus in a child.

Assessment within 1–3 days:

• distortion of straight lines or a central spot in the visual field;
• reduced distance or near vision;
• difficulty driving at night;
• persistent dryness, burning or watering for more than two weeks;
• gradually increasing “haze” or cloudiness;
• frequent squinting, headaches while reading, or bringing objects close to the face in children;
• any new eye symptoms in a person with diabetes.
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— Do you often encounter situations in which vision could have been preserved if the patient had sought medical attention earlier?

Unfortunately, yes. This is one of the most common causes of irreversible vision loss.

Typical examples include:

• glaucoma diagnosed only at the “tunnel vision” stage;
• retinal detachment in patients who waited for the “curtain” to disappear;
• proliferative diabetic retinopathy in people who had never undergone a fundus examination;
• wet age-related macular degeneration diagnosed late;
• corneal ulcers in contact lens wearers or patients who self-medicated;
• amblyopia diagnosed after the age of 8–9.

According to the WHO World Report on Vision (2019), at least 1 billion people worldwide have vision impairment that could have been prevented or has yet to be appropriately addressed.

— If someone sees well, has no pain and has never visited an ophthalmologist, why should they undergo preventive eye examinations?

To detect disease while there is still an opportunity to preserve vision. Many sight-threatening conditions, including glaucoma, diabetic retinopathy and macular degeneration, can be asymptomatic in their early stages.

A routine eye examination usually takes 20–30 minutes and may include visual acuity testing, IOP measurement, fundus examination and, when indicated, OCT.

An approximate screening schedule:

• healthy adults — a baseline examination at age 40; every 2–4 years until age 54, every 1–3 years between 55 and 64, and every 1–2 years after 65;
• earlier and more frequently for people with diabetes, hypertension, a family history of glaucoma, high myopia, contact-lens use, long-term corticosteroid use, autoimmune disease or previous eye trauma;
• children — at ages 3–5, before starting school, and every 1–2 years thereafter; children with myopia should generally be examined every six months.

DON'T WAIT UNTIL YOUR VISION GETS WORSE

One of the most important principles in ophthalmology may sound paradoxical: good vision today does not always mean that your eyes are completely healthy. Some diseases develop gradually, and people simply adapt to the changes. Others may remain painless and cause little or no noticeable discomfort for a long time. In certain conditions, however, how quickly a person seeks medical attention directly affects whether their vision can be preserved.

That is why preventive eye examinations are important — not only when vision has already deteriorated, but to identify problems before they begin to threaten sight.

We often take our vision for granted — until we begin to lose it.