The link between statin use and cataracts has been the subject of a number of studies but results have been somewhat conflicting. Cardiologist Robert Xuereb and ophthalmologist Franco Mercieca share their opinion on the subject with Jennifer Grech.

Blue, green, grey, hazel or brown. Big, small, wide, round or almond-shaped. The eyes are our windows to the world but it is important to remember that windows can get dirty and misty and need looking after if you want to see amazing views through them.

A recent visit to the ophthalmologist with my husband left me dumbfounded as I learnt that cataracts are not necessarily age-related.

“You have a cataract in your left eye,” ophthalmic surgeon Franco Mercieca told my husband.

“But he’s still in his 40s!” I humbly replied.

Cataracts form when proteins begin to clump together in the lens, clouding a small area of the eye. This ‘cloud’ continues to grow and interfere with vision and it can occur in one or both eyes.

Cataracts can also be caused by eye trauma and various environmental and lifestyle factors.

Past observational studies have turned up conflicting findings about the possibility of developing cataracts after taking certain medication, including statins and anti-diabetic drugs.

My husband takes statins. A large British observational study in 2010 found a small but significant increase in cataracts in statin users. Experts, however, warn that without further support the finding should probably not influence clinical practice.

Although studies have shown that statin use may be associated with cataracts, authors conclude that further studies are warranted to confirm their findings

For reasons that remain somewhat under wraps (are they, really?), drug companies have been able to downplay the risk of cataracts associated with the use of statins for 25 years. Also, very few physicians ever mention this as a complication of statin therapy.

Here is something most doctors know but tend not to mention: the lens of the eye actually requires cholesterol to stay healthy and transparent. Without adequate cholesterol, specialised epithelial cells in the eye cannot grow normally.

Animal studies have demonstrated that interfering with cholesterol synthesis in the eyes increases the likelihood of cataracts. People who have naturally-low cholesterol levels because of their genetic make-up are at greater risk of developing cataracts.

So many of the puzzle pieces may start to fit together.

Lovastatin was the first of the new-generation statin-type cholesterol-lowering drugs on the market. But even before the drug was approved, studies on dogs suggested that lovastatin might trigger cataract formation.

A review in the journal Pharmacotherapy in 1987, titled Lovastatin: A New Cholesterol-Lowering Drug, noted: “The most common adverse effects are gastrointestinal, while the most serious are elevated transaminase levels and the potential for lens opacities.”

The cataract connection began to get traction when a large study by the British Medical Journal (BMJ) in 2010 involving over two million patients detected a signal.

The authors reported that “each statin was associated with an increased risk of cataracts in both men and women… After stopping treatment the risk of cataract returned to normal within a year in men and women”.

Benefits of statins ‘outweigh risks’

In 2012, Canadian researchers noted that patients with diabetes who were taking statins were at nearly 50 per cent greater risk of cataracts. The authors recommended that people with diabetes who are taking statin-type drugs should be monitored for cataract development.

Robert Xuereb, chairman of the Department of Cardiology, and Franco Mercieca, consultant ophthalmic surgeon, are in total agreement on this issue.

“Although some studies have shown that statin use may be associated with cataracts, authors conclude that further studies are warranted to confirm their findings,” Xuereb says.

“On the other hand, a large meta-analysis of 14 studies showed beneficial effects of statins in reducing the risk of cataracts, especially in younger patients who were on long-term statin therapy.

“The authors in fact conclude that ‘this meta-analysis indicates a clinically relevant protective effect of statins in preventing cataracts. The effect is more pronounced in younger patients and with longer duration of follow-up’.

Even if cataract risks were increased by a small amount, the substantial benefits of statin therapy would continue to outweigh the risks

“In conclusion, the evidence for an association of statins with cataracts is as yet conflicting and large international multicentre randomised double-blind studies are needed to clarify the issue.

Xuereb, however, says that the benefits of statins outweigh the risk of cataract surgery.

“What we definitely know is that in patients at a high risk of cardiovascular disease, the prevention of a heart attack, stroke and death vastly outweighs the risk of cataracts,” he claims.

“Even among lower-risk patients, preventing a major cardiovascular event is much more important than the risk, if it really exists, of undergoing earlier non-life-threatening cataract surgery.”

For people who have heart disease, have experienced a heart attack or have stents in coronary arteries, the benefits of drugs like atorvastatin (Lipitor), lovastatin (Mevacor), pitavastatin (Livalo), fluvastatin (Lescol), pravastatin (Pravachol), rosuvastatin (Crestor) and simvastatin (Zocor) may well be worth the risks. Those who are otherwise healthy should discuss these findings with a physician. “Cataracts are not a trivial side effect,” he says.

Mercieca also refers to past observational studies that have turned up conflicting findings about the effects, if any, of statins on developing cataracts.

“There have been studies published in peer medical journals which are suggesting a higher risk of cataract formation in patients on statins. However, there is no evidence that statins actually cause cataracts. Also, patients on statins usually have other co-morbidity which have been relatively ignored in some studies.

“In fact we notice that patients who suffer from various medical illnesses do develop cataracts at an earlier stage than their healthier counterparts. After all, a cataract occurs due to a chemical imbalance within the lens of the eye and therefore its formation is commoner in diabetics and other metabolic disorders.

“On the other hand, the dangers of cardiovascular disease secondary to high lipids far outweigh the dangers of cataract surgery, and therefore even if this association would be verified in the future as having a stronger tie, it should not restrict the use of statins.”

Mercieca is adamant that patients should make an informed decision before starting statin therapy.

“Ethically and professionally, all patients being started on statins should be informed of all possible risks or side effects from their use. After all, the medic is only advising in his best knowledge to the benefit of the patient and it is the latter who in the end should consent for any treatment. Informed consent is a must,” he says.

Xuereb adds that understanding and optimising the modifiable risk factors “is not exactly a game-changer or a reason to avoid statins”.

“Even if cataract risks were increased by a small amount, the substantial benefits of statin therapy would continue to outweigh the risks, especially since treatment for cataracts is extremely safe and effective.”