When does a cataract become symptomatic?

A cataract is the progressive clouding of the crystalline lens, the eye’s natural lens located inside the eye. Normally transparent, this lens becomes cloudy with age: the proteins that make it up clump together and less light reaches the retina. Vision then becomes blurred, as if you were looking through a fogged-up windscreen.

The leading cause of correctable vision loss worldwide, cataract affects more than one French person in five after the age of 65 and nearly the entire population after 85. It is not a disease but a natural change in the eye, like greying hair. It can, however, appear earlier in cases of high myopia, diabetes, eye trauma, prolonged corticosteroid treatment or after certain intraocular surgeries.

The 7 most common symptoms

A cataract develops gradually, often over several months or years. The following signs should raise concern and prompt an eye examination, especially after the age of 55:

1. Vision that becomes blurred or hazy

This is the most typical symptom. Sharpness gradually decreases, outlines become less defined, and reading becomes a strain even with good glasses. Vision can seem misty, as if through frosted glass. This blur cannot be corrected by cleaning your glasses or by blinking.

2. Marked sensitivity to light (glare)

Sunlight, headlights at night and the strip lighting in a shop become dazzling and unpleasant. Driving at night becomes uncomfortable, even dangerous. This abnormal glare (photophobia) is highly suggestive of an early cataract, particularly a so-called posterior subcapsular cataract.

3. Halos around lights

Genuine coloured or whitish halos appear around light sources: car headlights, streetlamps, television screens. These halos are caused by light scattering through the lens that has become opaque. They are particularly troublesome when driving at night.

4. Dull or yellowed colours

The cataractous lens absorbs blue wavelengths: colours look dull and whites turn yellowish. Many patients realise after surgery that they could no longer see blues or purples accurately. Visual contrast also decreases, which makes reading road signs at dusk more difficult.

5. Double vision in one eye (monocular diplopia)

Rarer but highly suggestive: even with the other eye closed, you see two slightly offset images of the same object. This phenomenon reflects the optical irregularity of a lens that is clouding in sectors.

6. Needing to change glasses often

Patients notice that their prescription is unstable: myopia increases (or, paradoxically, presbyopia decreases at first, which is known as “index myopia”). Some long-sighted patients temporarily regain the ability to read without glasses, a misleading but telling sign. If your lenses seem to become outdated quickly, mention it to your eye doctor.

7. A decline in everyday visual performance

More insidious but just as important: you read less, you avoid driving at night, you no longer recognise faces from a distance, and the cinema or your hobbies lose their appeal. This loss of visual independence is often downplayed by patients who gradually adapt to their impairment.

When should you see an eye doctor?

An eye examination is recommended as soon as any one of these symptoms appears, even on its own. It is all the more pressing if:

• You are over 60 and have not had an examination in more than two years;
• You drive regularly, especially at night;
• Your work or hobbies require precise vision (reading, detailed work, sport);
• You have high myopia, diabetes, raised eye pressure or a family history of AMD or glaucoma;
• You are on long-term corticosteroids (asthma, rheumatoid arthritis);
• You have had a past eye injury or previous eye surgery;
• You notice a rapid worsening (over a few weeks) of your vision;
• You have falls or a sense of visual insecurity, even occasionally.

The consultation makes it possible to confirm the diagnosis (slit-lamp examination after dilation), to rule out another cause of vision loss (AMD, glaucoma, diabetic retinopathy) and to explain your options. Dr Moïse Tourabaly sees patients in Cachan (94) and in Paris; surgery, when indicated, is performed at Clinique Sainte-Geneviève (Paris 14).

When does surgery become necessary?

Today there is no longer a criterion of a “ripe enough cataract” before operating. The decision rests on the functional impairment experienced by the patient: as soon as the cataract prevents comfortable reading, safe driving or the pursuit of daily and professional activities, surgery is justified.

According to international guidelines, the following objective criteria support surgery:

• Corrected visual acuity below 6/10 that interferes with daily life;
• Significant glare in night-driving conditions;
• Loss of contrast confirmed on examination;
• Troublesome anisometropia (a difference in prescription between the two eyes that has become intolerable);
• A cataract preventing monitoring of the fundus in another condition (AMD, diabetic retinopathy).

Cataract surgery is today the most commonly performed operation in France (more than 800,000 per year). It is carried out as a day case, under topical anaesthesia (drops), takes about ten minutes and allows rapid visual recovery within a few days in 95% of cases. A dedicated page on the procedure describes how it is performed at Clinique Sainte-Geneviève.

Warning signs: do not wait

Some symptoms call for an urgent consultation, within 24 to 48 hours. They do not always correspond to a cataract but can mimic one:

• Sudden loss of vision (over a few hours or days) in one eye: suggests a retinal detachment, a vascular occlusion or optic neuritis.
• Flashes of light (phosphenes) or the sudden appearance of a large number of “floaters” (myodesopsia).
• A dark veil or loss of part of the visual field.
• A red, painful eye with reduced vision, especially after recent surgery (risk of endophthalmitis).
• Distorted vision of straight lines (wet AMD).

Apart from these emergencies, a cataract does not require a short timescale: it can be operated on whenever you wish, on a schedule chosen together with your surgeon.

Frequently asked questions

Sources

• Chylack LT Jr, Wolfe JK, Singer DM, et al. The Lens Opacities Classification System III. The Longitudinal Study of Cataract Study Group. Arch Ophthalmol. 1993;111(6):831-836. PMID 8512486. The reference LOCS III classification for grading cataract (nuclear, cortical, posterior subcapsular).
• Mönestam E, Wachtmeister L. The impact of cataract surgery on low vision patients: a population based 2-year follow-up study. Acta Ophthalmol Scand. 1997;75(5):569-576. PMID 9469558. Functional impact of cataract symptoms and the benefit of surgery.
• Haute Autorité de Santé. Chirurgie de la cataracte chez l’adulte — recommandations de bonne pratique. HAS, 2018 (updated 2024). Indication criteria and care pathway.

This page is for information only and does not replace an individual consultation. To understand the full pathway from diagnosis through to recovery, see also the cataract page.

Unsure about your vision? See Dr Tourabaly

Full examination in Cachan (94) or in Paris. Surgery at Clinique Sainte-Geneviève (Paris 14) if the operation is indicated.

Scientific sources

• Huang AY, Rao N, Armenti ST. Dropless Cataract Surgery: A Review of the Literature. Int Ophthalmol Clin. 2025 ;65(2):44-54. DOI : 10.1097/IIO.0000000000000560
• Alvarado-Villacorta R et al. Surgical interventions for presbyopia. Cochrane Database Syst Rev. 2025 ;4(4):CD015711. DOI : 10.1002/14651858.CD015711.pub2
• Bobot N et al. Effect of Femtosecond Laser-Assisted Versus Conventional Clear Corneal Incisions on Endothelial Cell Density and Surgical Efficiency. J Clin Med. 2026 ;15(2):626. DOI : 10.3390/jcm15020626

Page written by Dr Moïse Tourabaly, ophthalmic surgeon, for information purposes. It in no way replaces a medical consultation.