Cataract surgery can transform someone’s life. Usually, most patients can see clearly within days and will never look back. However, there are a few patients for whom the artificial lens replacing the cloudy cataract shifts and does not sit correctly in its required position.
Doctors call this intraocular lens (IOL) dislocation, and it can even occur months or years after the operation.
So why do IOLs get dislocated? When the structures that normally support the IOL become loose or rupture, the structure (the capsular bag and the zonular fibers) cannot support the lens, which ultimately moves away from its normal position and, in turn, interferes with vision.
What Is an Intraocular Lens?
In cataract surgery, the natural lens inside your eye is removed and replaced by a clear, artificial lens. This artificial lens is your IOL.
Inside the eye, the IOL is contained within a clear, paper-thin pouch known as the capsular bag. Thread-like fibers that hold the capsular bag and its contained IOL to the eye’s internal structure are known as zonules. Imagine them as the spokes of a bicycle wheel, keeping your lens perfectly in place.
Weak zonules or a tear in the capsular bag can cause the IOL to become unanchored, leading to lens dislocation.
What Causes Intraocular Lens Dislocation?
IOL dislocation occurs when the capsular bag is traumatized, zonular fibers are compromised, or both are involved. Surgeons divide these causes into early and late dislocation.
Causes of Early IOL Dislocation (Within 3 Months of Surgery)
Early dislocation refers to a dislocation that occurs immediately after the surgery. Early dislocation usually indicates a surgical complication. Causes can be:
- Rupture Of The Capsular Bag – This means that during surgery, the capsule breaks, so the bag cannot fully support the IOL.
- Zonular Damage – means that during surgery, instruments used strain inadvertently and then rupture zonular fibers.
- Incorrect IOL Placement – means that after insertion into the capsular bag, the lens is not in the correct place.
- An Abnormal or Too Small Capsulotomy – this is the opening made in the anterior of the capsule, and it is the lens support that can not be formed correctly with this abnormality.
Early dislocation is uncommon, with most IOL dislocations occurring later in life.
Causes of Late IOL Dislocation (Months or Years after Surgery)
It is much more common for a late dislocation. The mean time to late IOL dislocation after cataract surgery is over 7 years. These problems develop slowly, long after surgery seems complete.
Here is a list of the most frequent causes for late IOL dislocation:
- Pseudoexfoliation Syndrome (PEX) – This is by far the most frequent cause for late IOL dislocation. PEX involves an accumulation of fluffy deposits resembling dandruff throughout the eye; over time, these can destroy the zonular support. In many patients with PEX, the condition remains undiagnosed until the cataract surgery.
- History of Prior Vitreoretinal Surgery – The prior vitrectomy (surgery on the cavity inside the eye) removes the vitreous, which supports the capsular bag and thus makes IOL and bag destabilization more likely.
- High Myopia – A highly nearsighted eye is longer than a normal eye, and this creates undue stretching and stress on the zonules.
- Chronic Uveitis – Inflammation over a long time period slowly destroys the capsular bag from the inside out.
- Trauma To The Eye – A direct blow to the eye at any point following cataract surgery can damage zonules. Trauma remains a significant risk long after the surgery is completed.
- Retinitis Pigmentosa – This is an inherited disorder that slowly weakens the zonules with age.
- Capsular Contraction Syndrome – The capsular bag contracts, placing increased strain on the already weakened zonules.
- YAG Capsulotomy – This laser is used to correct cloudy vision after cataract surgery. Still, in patients with already weak zonules, it can trigger IOL subluxation.
- The Passage Of Time – Zonules weaken with age, and even in people without other risk factors, over decades, the zonules may deteriorate sufficiently to allow the IOL to subluxate or dislocate.
Medical Conditions That Raise Your Risk
Some underlying conditions are associated with a higher risk of IOL dislocation. Discuss your health history (not just eye history) with your retina specialist.
High-risk conditions include:
- Marfan Syndrome: A connective tissue disorder that directly weakens zonular fibers.
- Ehlers-Danlos Syndrome: A connective tissue disorder that also influences the structure of the eye.
- Weill-Marchesani Syndrome: Affecting the small, round lens. Dislocate very easily.
- Homocystinuria: A metabolic disorder with an even higher correlation to lens dislocation.
- Diabetes Mellitus: Affects the long-term integrity of the capsular bag.
- Atopic Dermatitis: Patients with this condition tend to rub their eyes. The repeated act causes repeated micro-trauma and wears down the zonular fibers.
- Glaucoma: Having a history of glaucoma, you have a predisposition to having zonular instability.
If any of these conditions are present, you need to have your IOL closely observed.
Who Is Most Likely to Develop IOL Dislocation?
While not prevalent- 0.2% and 3% of cataract patients have this condition- IOL dislocation poses a significantly greater threat to a subset of patients. If you are a patient:
With pseudoexfoliation syndrome.
- Who underwent a prior vitrectomy procedure?
- With high myopia (excessive nearsightedness).
- Over 65 years of age
- Who experienced a complex cataract extraction?
- Who is male (male patients are seen to have a higher risk of IOL dislocation than women).
- With a connective tissue disorder (such as Marfan syndrome).
Then your risk of IOL dislocation is higher, and this information will allow your physician to be more careful and alert to signs of dislocation.
The Warning Signs You Should Never Ignore
IOL dislocation isn’t always a sudden event; some people experience a gradual progression of symptoms, while others may experience a more abrupt change. Regardless of when it occurs, the signs and symptoms need to be addressed by your ophthalmologist.
These symptoms can be warning signs of IOL dislocation following cataract surgery:
- A sudden shift in vision from clear to blurred or doubled.
- A feeling that your vision is tilted, or off to one side.
- The appearance of a curved shadow or “ring” within your vision (you’re seeing the edge of the lens).
- A quick, significant, and unexpected change in your glasses prescription.
- Increased light sensitivity and glare.
Do not put off calling your ophthalmologist. IOL dislocation can be a medical emergency in some circumstances. Understand when IOL dislocation requires urgent treatment.
How RVAF Treats a Dislocated IOL?
You can’t fix a dislocated IOL on your own. An IOL can only be repositioned by a vitreoretinal surgeon.
RVAF has its own vitreoretinal surgeons who perform IOL reposition and IOL exchange surgery. Our vitreoretinal surgeons reposition the dislocated lens and exchange it using sophisticated scleral fixation methods when the lens itself is too deteriorated, or the capsular bag cannot accommodate the IOL.
Our practice is focused on safely restoring your vision accurately and enduringly. General ophthalmologists routinely refer their patients to RVAF. We have provided state-of-the-art retina care to the Tampa Bay area for 54+ years.
Frequently Asked Questions about IOL Dislocation
1. Can An IOL Dislocate Years After Cataract Surgery?
Right, late IOL dislocation is the majority. The average time of late IOL dislocation since the cataract surgery is greater than 7 years. Slow weakening of the zonule (pseudexfoliation or simple aging) accumulates over time after surgery.
2. Is IOL Dislocation The Same As Lens Subluxation?
No. Subluxation is the partial movement of the IOL out of the capsular bag. In contrast, a dislocated IOL is totally out of the capsular bag. Both need specialist assessment, but a full dislocation is more urgent.
3. Is Pseudoexfoliation The Biggest Risk Factor?
Yes. The most common reason for late IOL dislocation is pseudoexfoliation syndrome. Pseudoexfoliation is the most common cause that directly affects zonular fibers and is often unrecognized before surgery; therefore, patients with PEX should be followed long-term after cataract surgery.
4. Can IOL Dislocation Be Treated Successfully?
Yes. RVAF vitreoretinal surgeons can reposition the dislodged IOL. Patients generally regain good vision when they seek treatment early.
5. Can Rubbing Your Eyes Cause IOL Dislocation?
Repeated vigorous rubbing of the eyes causes cumulative micro-trauma. In the long term, it may damage the zonular fibers, particularly in predisposed patients, such as those with atopic eczema or pseudoexfoliation. Do not rub your eyes following cataract surgery.