During a cataract surgery an intra ocular [artificial lens] is placed in the capsule of the natural lens of the eye, after the cataract affected lens is removed. The capsule supports or holds the artificial lens and prevents dislocation. However, sometimes the lens gets dislocated from its original position to another position. This is known as dislocation of the IOL [intra ocular lens].
This is one of the major, but uncommon intra operative or post operative complication after a cataract surgery or an Nd YAG posterior capsulotomy. Dislocation of the intraocular lenses may occur due to trauma during surgery or with systemic diseases where the capsular support weakens.
IOL dislocations are categorised as ‘in-the- bag’ and ‘out- of- the- bag’. The most common in-the-bag etiologies are pseudoexfoliation [deposition of whitish-grey protein material on the lens surface] and prior vitreoretinal surgery. IOL dislocation could either be early if it’s within three months of cataract surgery or late if it’s beyond three months of cataract surgery. Dislocation of IOL has estimated occurrence in 0.2% to 3% of cases.
Signs and Symptoms
This depends on the degree of malfunction. The patient may notice the edge of the lens implant or even have double vision. If the lens implant dislocates entirely out of the visual axis, the patient may have a very substantial drop in visual acuity, usually to the “counting fingers” level.
Degree of malfunction:
- Mild (where the optic covers more than half of the pupillary space)
- Moderate (where the optic covers less than half of the pupillary space)
- Luxated (completely dislocated)
- Streaks of light.
- Sudden blurry vision.
- Decrease in vision.
- Edge glare.
- Diplopic (double vision).
- Induced astigmatism.
- Pseudo exfoliation
- Prior vitreoretinal surgery
- Trauma – Rubbing the eyes hard after cataract surgery can cause dislocation
- Increased Axial length
- Associated with syndromes such as Marfan’s syndrome
Diagnosis: A dilated slit-lamp examination is conducted along with other tests. One of the challenges which surgeons face is the movement of the bag – IOL as the location may changes according to your resting or sitting position during the examination.
Treatment: Usually treatment is surgical.
Dislocated IOL is treated by moving the lens into the correct position, or replacing the lens. In most cases the gel in the back of the eye, or vitreous, must be removed in part through the surgical process called “vitrectomy”. Once the lens is free of the vitreous gel it can be moved more safely and repositioned or replaced. In some cases a new lens can also be sewn into the back of the eye.
Hence, the treatment differs on a case to case basis.
Vitrectomy: This surgical procedure is conducted to remove the vitreous gel from the central cavity of the eye. The various approaches are Anterior vitrectomy (anterior approach to fixate the implant when the lens is subluxated but still stable within the anterior segment). In some cases the IOL is unstable or dislocated posterior into the vitreous cavity then IOL is retrieved through the posterior segment or a Pars plana Vitrectomy.
- IOL Removal – IOL is removed based on certain factors like damaged haptics, small optics, highly flexible haptics which does not support sutures, eyes with a poor visual prognosis, associated complicated retinal pathology such as retinal detachment, or damaged IOLs.
- IOL Repositioning – IOL is surgically rotated and repositioned and fixed in the right place..
- IOL exchange – Wrong IOL power and malposition is the main indication for the IOL exchange.
Depending on your type of IOL and specific anatomic considerations, you would be suggested on the type of treatment most suitable. The existing symptoms, visual needs, and expectations are considered before finalizing the treatment. We endeavour to give you the best treatment with minimal risk and long term visual outcome.