What is a cataract?

A cataract is a progressive clouding of the crystalline lens, the natural lens located behind the iris. With age, the proteins that make up the lens deteriorate, the lens turns yellow and then white, and less and less light passes through it. Vision becomes blurred, colors fade, contrast disappears, and sensitivity to glare increases. It is the world's leading cause of reversible blindness: according to the WHO, more than 94 million people worldwide are affected, and 65% of people in France over age 75 have cataracts to some degree.

There are several forms: nuclear cataracts, in the center of the lens; cortical cataracts, around its edge; posterior subcapsular cataracts, at the back and common in people with diabetes and patients on long-term corticosteroid therapy; and, more rarely, congenital cataracts. The most common cause is simply the physiological aging of the lens.

Key figure. In France, more than 830,000 cataract operations are performed every year, according to the French Society of Ophthalmology (SFO). It is the country's most frequently performed surgical procedure across all specialties.

When should you have surgery?

France's national health authority, the Haute Autorité de Santé (HAS), published updated recommendations on the surgical indication for cataracts in 2024. Three main criteria guide the decision.

Visual acuity

Historically, surgery was performed when acuity reached 5/10 on a Snellen chart. Today, that threshold is no longer treated as absolute: surgery may be offered at 7/10 if a person reports functional difficulties, while someone who is satisfied with their vision and remains independent may wait even at 3/10.

Loss of independence

This has become the main criterion. Can the patient no longer drive at night, recognize faces at a distance, read the newspaper, use the stairs safely, or manage their accounts? Any of these situations may justify surgery, even when acuity remains slightly above the old thresholds.

Contrast sensitivity and glare

Measured in the clinic with specific tests, these complete the picture. A cataract may produce “acceptable” acuity in a standardized test yet cause a real disability in daily life because of constant glare in bright light. To learn more about Lumyeye's role in this situation, our cataract support page explains how the app can help while you wait for surgery.

The preoperative pathway in France

The wait between the decision to operate and the procedure ranges from two months in private clinics in city centers to twelve months in public hospitals in underserved areas. These are the typical stages.

Surgical consultation

The ophthalmic surgeon assesses the lens, measures the eye's axial length through biometry, and calculates the power of the implant that will replace the lens. There are three main implant types: monofocal, which provides distance vision only and requires reading glasses; toric monofocal, which corrects astigmatism; and multifocal or extended-depth-of-focus implants, which provide near and distance vision without glasses but may create halos at night. The patient and surgeon choose together based on the patient's lifestyle.

Anesthesia consultation

This is required during the month before surgery. The anesthesiologist reviews the patient's general health and selects the type of anesthesia: topical, using drops alone in 90% of cases; peribulbar, with an injection around the eye; or general anesthesia, which is very rare and reserved for special circumstances.

Blood work and pausing blood thinners

Standard blood tests are performed. Depending on the risk, anticoagulants and antiplatelet drugs may be stopped as a precaution five days before surgery, in consultation with the cardiologist.

Buying the eye drops

The pharmacy dispenses the drops to use the day before surgery, on the day itself, and during the following weeks. These are generally an antibiotic, a steroid anti-inflammatory, and a nonsteroidal anti-inflammatory. A typical schedule is four applications a day for three to six weeks.

Surgery day: 15 minutes in the operating room, hours of emotion

The patient arrives at the hospital or clinic two hours before surgery. They change into sterile clothing, including shoe covers and a cap; receive mydriatic drops to dilate the pupil, which takes 30 to 45 minutes; have their face disinfected with povidone-iodine; and are covered with a sterile drape. The operation itself takes 12 to 18 minutes.

The surgeon makes a millimeter-scale incision at the edge of the cornea and inserts an ultrasound probe, or phacoemulsifier, that breaks up and suctions out the clouded lens. A flexible artificial implant is then inserted and unfolds in place. The incision closes on its own or is secured with a dissolvable stitch. Patients generally feel no pain—only bright light, a sense of movement, and sometimes a few drops of irrigation fluid.

The patient leaves the hospital two hours later with someone accompanying them home. A clear shield taped to the skin protects the operated eye and remains in place for the first night.

Recovery: day 1, day 7, day 30

Day 1: the postoperative appointment

The ophthalmologist checks the eye the following day. They measure intraocular pressure, which may be slightly elevated, examine the cornea with a slit lamp, and check for infection. Visual acuity is usually already much better: 60% to 80% of patients see better than before surgery by the next day.

Day 7: truly getting back to normal

The eye has healed. Colors look brighter and light appears warmer. Reading, walking, and daytime driving can resume. Restrictions still apply: no heavy lifting, swimming, makeup, or rubbing the eye. The eye drops continue.

Day 30: the assessment

At this follow-up, the ophthalmologist measures final acuity, checks the implant's position, and may prescribe additional glasses—simple reading lenses or correction for residual astigmatism. If needed, this is also the time to decide whether to operate on the second eye, generally one to four weeks later.

Jeanne's journal, age 71

“My name is Jeanne, I am 71, and I live in Tours. My ophthalmologist told me in 2024 that both eyes were developing cataracts. It grew slowly worse, like a fog. In 2025, I could no longer recognize my grandchildren at the end of the garden. I made my decision: surgery on my right eye on April 15, 2026, and the left on April 22.”

Day 0, April 15: “I arrived at the clinic at 7 a.m. Everything moved quickly. The surgeon joked, ‘You will see, Jeanne, you are going to get your colors back.’ In the operating room, I saw a very bright blue light and heard a soft sound like a small machine. Fifteen minutes later it was over. My vision was blurry when I left, but already different—as if someone had wiped a dirty window.”

Day 1: “I discovered the blue sky. Real blue. Not the yellowish blue I had seen for three years. I cried in the car. My husband thought I was in pain; I told him they were tears of joy.”

Day 3: “I read the newspaper without difficulty with my old glasses. I was amazed. The print was sharp; I had forgotten how sharp it could be.”

Day 7: “I see well at a distance with my right eye, but the left is still blurry—it is the next one to be operated on. Living with two eyes that do not see the same way is strange. I wear a patch for part of the day to rest.”

Day 8, April 22: “The second eye was operated on this morning. The same procedure, just as fast. Tonight I have the same clear shield, and tomorrow I will see in stereo for the first time in two years.”

Jeanne wrote to us the following week: “I have started sewing, gardening, and driving at night again. It feels like a second life is beginning.”

Lumyeye's role during recovery

During the weeks of recovery, vision may be temporarily blurred, contrast uneven, and reading tiring. This is precisely when a visual-assistance app can be especially useful—not to replace the sight that is returning, but to bridge the days when it fluctuates.

Several uses are particularly helpful at this stage:

  • Reading eye-drop leaflets and postoperative instructions: mixing up the right and left eyes, frequency, or order of application is a real risk.
  • Identifying bottles: antibiotic, NSAID, corticosteroid—three bottles with tiny labels.
  • Describing the eye in a mirror: to look for unusual redness or concerning swelling of the eyelid. A relative can also take a photo and have the app describe it.
  • Reading texts and emails from the ophthalmologist, appointment reminders, and phone instructions.
  • Reading labels on everyday products that are still difficult to see: medication, canned food, and administrative documents.

For people who had never used a visual-assistance app before surgery, this is often a discovery. Some continue using it afterward because, once you are used to having letters and labels read aloud, it remains convenient even when your vision is good again.

Secondary cataracts: when cloudiness returns years later

In 20% to 40% of operated patients, the posterior capsule becomes cloudy in the months or years after surgery. This is sometimes called a secondary cataract. It is not a recurrence in the strict sense—the implant has not moved—but a membrane behind it thickens and blurs vision again.

Treatment is very simple: a YAG laser capsulotomy performed in the clinic without anesthesia in two to five minutes. The result is immediate. It is painless, requires no recovery, and is fully reimbursed by France's national health insurance. If you had surgery three to five years ago and your vision is declining again, do not immediately assume there is another cataract elsewhere—ask to be checked for posterior capsule opacification first.

Practical advice before and after surgery

  • Prepare your home: remove rugs to reduce fall risk, improve the lighting, and keep sunglasses within reach because light sensitivity is strong during the first few days.
  • Let family and friends know: you will need help with groceries, driving, and perhaps meals for three to five days.
  • Follow the eye-drop schedule exactly: it is the leading factor in a good postoperative result and preventing infection.
  • Never rub the operated eye for four weeks, even if it itches.
  • Seek urgent care for severe pain, a sudden drop in acuity, or pronounced redness—possible signs of endophthalmitis, a serious but rare infection affecting about 1 in 2,000 patients.

In conclusion: surgery that changes a life

Cataracts are one of the few serious eye conditions that can be completely cured. Fifteen minutes in the operating room, a few weeks of healing, and sight returns. For older people who have watched their independence fade, it is a decisive event. For working-age adults who could no longer drive at night, it restores freedom.

If you are hesitating because surgery has been recommended and you are afraid, cataract surgery is now one of the safest and most predictable procedures in the world. The success rate exceeds 98%, while serious complications occur in fewer than 0.5% of cases. The only real risk is waiting too long.

Sources and references

Article written by Alban Clochet, founder of Lumyeye. The medical information provided here is for informational purposes and is not a substitute for your ophthalmologist's advice. Any surgical decision must be made in consultation with your doctor.