Most people pay no attention to the lens of their eye until their vision starts to change. The lens sits just behind the iris, clear and flexible in younger years, responsible for focusing light onto the retina. When it starts to cloud over, the result is a cataract.
Cataracts are the most common cause of reversible vision loss in older adults worldwide, and one of the most treatable. Knowing what causes them, how they develop and what surgery involves makes a real difference when you are trying to understand what is happening to your own vision, or to someone you care about.
What Is a Cataract?
A cataract is a clouding of the natural lens. The lens is made mostly of water and protein, and in a healthy eye those proteins are arranged to keep it transparent. Over time, through ageing, UV exposure and oxidative damage, the proteins begin to clump, creating patches of cloudiness that scatter light rather than focus it cleanly.
Vision becomes progressively blurred or hazy. Colours may look washed out. Night driving gets harder, with glare and halos appearing around headlights and streetlights. Reading that once required no effort begins to take concentration. Because these changes happen gradually, often over years, many people do not register how much their vision has declined until a formal test makes it obvious.
What Causes Cataracts?
Cataracts rarely come from one thing. They develop through a combination of factors, and in most people several are at play at once.
Ageing
Ageing is the most common cause by a significant margin, and understanding how it works helps explain why cataracts progress the way they do. The lens proteins accumulate damage over decades, and by the seventies some degree of clouding is considered a normal part of getting older. This type, called an age-related or senile cataract, typically affects both eyes, though usually not at the same rate or to the same degree.
For many people, the early stages cause minimal disruption. Vision shifts gradually, and it can be years between first noticing a change and reaching the point where surgery makes sense. In that time, updated glasses and improved lighting often compensate well enough that the cataract stays in the background of daily life.
The rate of progression varies considerably between individuals. Some experience relatively stable vision for many years; others find the cataract advances quite quickly once it has started. Regular monitoring with an eye specialist helps track where things are heading and makes the timing of any intervention easier to plan.
UV light exposure
Cumulative UV-B exposure accelerates the oxidative damage that drives cataract formation. People who spent years outdoors without UV-protective eyewear are at higher risk of developing cataracts earlier than those who protected their eyes consistently. Quality sunglasses that block both UV-A and UV-B, worn across a lifetime, are thought to slow this process.
Diabetes
People with diabetes develop cataracts more often and at younger ages than the general population. High blood glucose alters the metabolism of the lens in ways that speed up clouding, and diabetic cataracts can progress quickly, sometimes over months rather than years. Regular eye examinations that specifically check lens clarity are important for anyone with diabetes, as earlier detection gives more options around the timing and type of intervention.
Corticosteroid use
Long-term use of corticosteroid medications, whether oral, inhaled or topical, is associated with a specific type called a posterior subcapsular cataract. This forms at the back of the lens and can affect vision relatively quickly even at an early stage, because of its position in the optical path. Anyone on long-term steroids should flag this with their specialist so that monitoring is in place.
Eye injury
Blunt trauma, penetrating injuries and chemical burns can cause cataracts, sometimes rapidly and sometimes years after the original injury. In New Zealand, ACC covers cataract surgery when the cataract is a direct result of a qualifying injury.
Smoking, heavy alcohol use, radiation exposure and family history also play a role. If cataracts developed early in a parent or sibling, mention it to your eye specialist.
Types of Cataracts
Not all cataracts behave the same way, and understanding the type often explains why two people with the same diagnosis can have quite different experiences.
Nuclear cataracts form in the centre of the lens and are the most common type associated with ageing. They tend to develop slowly, causing a gradual loss of distance vision. Some people notice a curious temporary improvement in near vision in the early stages, a phenomenon called second sight, before the cataract advances further.
Cortical cataracts develop in the outer layers and extend inward in a spoke-like pattern. They tend to produce significant glare, particularly in bright light and when driving at night, even when the overall impact on baseline vision seems modest.
Posterior subcapsular cataracts form at the back of the lens capsule and are associated with steroid use and diabetes. They can progress faster than other types and cause disproportionate visual difficulty because of where they sit in the optical pathway, sometimes even when they are still relatively small.
Congenital cataracts are present at birth or develop in early childhood and require prompt treatment to prevent lasting impairment during the critical developmental window.
How Cataracts Progress
In most people, cataracts worsen over time. The rate varies considerably depending on the cause, overall health and whether factors like UV exposure or blood glucose are being managed.
In the early stages, updated glasses and better lighting can compensate for the changes. As the cataract advances, that becomes less effective. The cloudiness scatters light in ways that no optical correction can fix, and at that point surgery is the only path to clear vision.
No medication, eye drop or supplement has been shown to reverse or stop cataract progression in humans. Once the process is underway, it does not reverse on its own.
When Does a Cataract Need Surgery?
The decision to operate is not based on how a cataract looks under examination. It is based on how it is affecting someone’s daily life. A person with a moderately advanced cataract and modest visual demands may manage comfortably without surgery for a long time. Someone with an early cataract who drives regularly or works at a screen may find the impact significant much sooner.
Signs that surgery is worth considering include difficulty driving at night, struggling to read or watch television comfortably, increasing glare sensitivity and finding that glasses no longer provide satisfactory clarity. A specialist assessment weighs the degree of clouding against what the patient actually needs their vision to do.
What Does Cataract Surgery Involve?
Cataract surgery is one of the most commonly performed surgical procedures in the world. At Eye Surgeons, our team of five fellowship-trained ophthalmologists has performed over 10,000 successful procedures across our purpose-built surgical facilities in Hamilton, Cambridge, Pukekohe and Whanganui. The cloudy natural lens is removed and replaced with a clear artificial lens, an intraocular lens or IOL, designed to remain in place permanently.
Modern surgery uses small incisions that require no stitches. It is performed under local anaesthetic, takes around fifteen to thirty minutes, and is painless. Most patients notice a clear improvement within the first day or two.
One aspect of our approach that patients consistently appreciate is our dropless technique. Medication is delivered during the procedure rather than requiring a post-operative drop regimen at home. For most Eye Surgeons patients, this means leaving the clinic on the day of surgery without any drops to manage.
We also routinely perform Immediate Sequential Bilateral Cataract Surgery (ISBCS), treating both eyes at the same sitting. Most patients coming through our Hamilton, Cambridge, Pukekohe and Whanganui clinics have both eyes treated on the same day, meaning one recovery period, one set of post-operative instructions and a much faster return to full visual function.
Choosing the Right Lens
The lens you receive is the part of cataract surgery that has the most lasting impact on how well you see, and it deserves careful discussion.
Eye Surgeons is a Rayner Centre of Excellence and works with one of the widest ranges of premium lens technologies available in New Zealand, with over 20 options to suit different visual needs and lifestyles. Our lens portfolio includes the Rayner Galaxy full range lens, the Alcon PanOptix Pro trifocal, the Lentis Comfort (MF15), the IC8 small aperture lens and custom lenses manufactured in Italy. We are also the only provider in New Zealand currently offering the Lenstec ClearView 3.
Standard monofocal lenses restore clear vision at one distance, typically for distance, with reading glasses still needed for close work. Premium options can deliver clear vision across a wider range of distances and reduce glasses dependence substantially. The right lens depends on the characteristics of your eye, your lifestyle and what you want from your vision after surgery. That discussion sits at the centre of every consultation we do.
Cataract Surgery in NZ: What to Expect at Eye Surgeons
Our five fellowship-trained ophthalmologists bring specialist expertise across cataract, cornea, retina, glaucoma and medical eye conditions. Outcomes are independently audited, and our complication rates are significantly lower than expected based on patient risk profiling. At our most recent credentialling audit by the DAA Group, covering our Hamilton and Whanganui surgical facilities, we were formally commended for innovative use of technology to support patient outcomes, service efficiency and communication with patients.
A consultation begins with a comprehensive assessment: measuring the eye for lens selection, evaluating the degree of cataract and discussing your visual goals. That shapes both the lens recommendation and the surgical plan. Surgery is generally booked within a few weeks of the decision to go ahead.
Pricing is transparent and available on our website. We see privately funded patients, insurance-funded patients and ACC-funded patients where applicable.
To book at our Hamilton, Cambridge, Pukekohe and Whanganui clinics visit www.eyesurgeons.co.nz or call 0800 228 27 228.
Frequently Asked Questions
At what age do cataracts typically develop?
Most age-related cataracts become noticeable from the late fifties onward, though other causes including injury, steroid use and diabetes can bring them on at any age.
Can cataracts be prevented?
There is no guaranteed prevention. UV-protective eyewear, not smoking and good blood glucose management if you have diabetes all reduce risk or slow progression. Regular eye examinations help catch changes early, which gives more options around the timing of treatment. Beyond that, some degree of lens ageing is simply part of getting older.
Is cataract surgery covered by insurance in NZ?
Most private health insurance policies in New Zealand include some level of cover for cataract surgery, though the details vary considerably between policies. Standard lens options are more consistently covered than premium choices, so it is worth reading your policy carefully and speaking to your insurer before your consultation. If your cataract developed as a direct result of a qualifying injury, ACC funding may be available. Our team across our Hamilton, Cambridge, Pukekohe and Whanganui clinics can help you work through both processes.
What is dropless cataract surgery?
Medication is delivered during the procedure itself rather than requiring patients to instil eye drops at home afterwards. Most Eye Surgeons patients leave the clinic on the day of surgery without a drop regimen to follow.
What is the difference between public and private cataract surgery in NZ?
Public surgery is funded but waiting times can extend to many months, and lens choice is typically limited to standard options. Private surgery at Eye Surgeons offers faster access, over 20 premium lens options, same-day bilateral surgery in most cases and the dropless technique. The surgical procedure itself is the same quality in both settings, but the experience, the range of options and the speed of access are very different.
