Understanding Cataracts
Symptoms, causes, and diagnosis: the key information to know when to seek care.
A gradually developing condition
A clouding of the lens
A cataract is a progressive clouding of the crystalline lens, the eye's natural lens located behind the iris. Unlike glaucoma or AMD, cataracts are completely curable through surgery.
A slow progression
The condition most often progresses slowly, over several months or years. Vision becomes blurry, dull, and increasingly sensitive to light. There is no medical treatment: surgery is the only way to treat cataracts.
Both eyes affected
Both eyes are most often affected, but they do not necessarily progress at the same rate.
What are the typical signs of cataracts?
Progressive blurred vision
Loss of sharpness is the most common and earliest symptom — like looking through a dirty or foggy window. It is not improved by new glasses: this is a key sign.
Halos and glare
The abnormal scattering of light through the clouded lens causes glare when facing sunlight, headlights, or bright lights. Light halos often appear at night and can interfere with night driving.
Reduced contrast and color perception
Contrasts appear less defined, and colors look yellowed, dull, or less vibrant. This phenomenon is often imperceptible in daily life, but is strikingly revealed after surgery.
Double vision
Two overlapping images seen with a single eye (which disappears when closing the affected eye) may be perceived. This sign reflects irregular refraction through different zones of the lens.
Frequent prescription changes
The need to change glasses frequently without lasting improvement. A paradoxical phenomenon is possible: a transient improvement in near vision (myopic shift caused by the cataract), sometimes allowing reading without glasses after years of presbyopia.
Fixed veil or spot
A sensation of a permanent veil, haze, or fixed gray spot in the visual field. This should be distinguished from floaters (myodesopsia), which move with eye movements.
Simulate your symptoms
Click on a symptom to visualize the corresponding visual disturbance.
What are the causes of cataracts?
The causes are multiple. The most common is the natural aging of the lens, but other factors can promote earlier onset or faster progression.
Age
This is the primary factor. Over time, the fibers of the lens change and gradually become more opaque. Cataracts are particularly common after age 60, but can occur earlier.
Sun exposure and smoking
Chronic exposure to ultraviolet (UV) rays without eye protection can accelerate the degradation of lens proteins. Tobacco also increases oxidative stress and promotes ocular aging.
Diabetes and certain systemic diseases
Diabetes is a significant risk factor: excess sugar alters the metabolism of the lens and can accelerate its loss of transparency. Other inflammatory or metabolic diseases may also play a role.
Medications, particularly corticosteroids
Long-term corticosteroid treatments (oral, inhaled, or topical) are known to promote the development of cataracts.
Trauma and specific forms
There are also traumatic forms (following a direct blow to the eye), congenital forms (present from birth), or forms secondary to prior ocular surgery or certain inflammatory conditions.
How is the diagnosis confirmed?
The diagnosis is based on a comprehensive ophthalmological examination.
Slit-lamp examination
Observation of the lens confirms the clouding and determines its type: nuclear, cortical, or posterior subcapsular. The examination also assesses the overall condition of the eye.
When to consult? When to operate?
The only treatment is cataract surgery. It is not urgent in the vast majority of cases, but the surgical indication is established as soon as visual impairment affects your quality of daily life.
It is advisable to consult an ophthalmologist as soon as you notice:
Difficulty driving
At night (glare from headlights) or during the day (insufficient vision to read road signs). The law requires a minimum binocular visual acuity of 5/10 to drive.
Difficulty reading
Difficulty reading even with recent glasses, rapid eye fatigue, need for very bright lighting or holding a book very close or very far away.
Difficulty working on screen
Reduced productivity, headaches, or visual fatigue at the end of the day.
Prescription no longer effective
Changing glasses without satisfactory improvement, or an unstable prescription for several months.
Cataracts and associated conditions
Other ocular diseases may be associated with cataracts, which is why a complete pre-operative assessment is systematically performed.
AMD or a macular epiretinal membrane may be associated with cataracts. These conditions are detected by pre-operative macular OCT.
Glaucoma is a common condition that cataract surgery most often helps to stabilize.
In cases of corneal involvement, such as cornea guttata, precautions are taken to preserve it during the procedure.
References & medical sources
- Haute Autorité de Santé (HAS). Chirurgie de la cataracte chez l'adulte — indications et information du patient. Paris : HAS ; 2023.
- Société Française d'Ophtalmologie (SFO). Rapport annuel SFO — La cataracte : épidémiologie, diagnostic et prise en charge. Paris : Éditions Masson ; 2022.
- Liu YC, Wilkins M, Kim T, Malyugin B, Mehta JS. Cataracts. Lancet. 2017;390(10094):600–612. doi:10.1016/S0140-6736(17)30544-5
- Asbell PA, Dualan I, Mindel J, et al. Age-related cataract. Lancet. 2005;365(9459):599–609. doi:10.1016/S0140-6736(05)17911-2
- Organisation mondiale de la Santé (OMS). Rapport mondial sur la vision. Genève : OMS ; 2019.
- Lundström M, Barry P, Henry Y, Rosen P, Stenevi U. Evidence-based guidelines for cataract surgery. J Cataract Refract Surg. 2012;38(6):1086–1093.