Clear lens extraction, also known as refractive lensectomy, is a surgery that involves removal of the natural lens of the eye. It is similar to a cataract surgery, only that the lens being removed is clear, not clouded. The lens removed is replaced with an artificial one.
The surgery utilizes the phacoemulsification technique for extraction. Only a small incision is made to get the lens out and put the new one in. The suture heals by itself, requiring no stitching. Compared to laser- assisted therapies, clear lens extraction is a more invasive surgery. It is indicated where other vision correction surgeries are not suitable.
Clear lens extraction is indicated for refractive errors such as:
- Presbyopia - In presbyopia, the natural lens loses ability to focus. The condition is common around the age of 40 when the lens becomes rigid. Other refractive surgeries do not directly correct loss of vision arising from presbyopia. When the lens is extracted and replaced in refractive lensectomy, the vision improves significantly.
- Hyperopia – Patients who are extremely farsighted can benefit from the surgery. The lens is replaced with one that can focus correctly for near vision.
- Astigmatism – Blurred vision is common in astigmatism. The corneal or lens curvature is usually the cause. The condition often occurs together with farsightedness. A replacement lens exchange corrects the distorted vision.
- Myopia – The operation is also performed in cases of high myopia where other refractive procedures are not suitable. More common surgeries used are laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).
Preparation & expectation before Surgery
Before the surgery, the surgeon discusses with the patient the choices available for the lens replacement. They include:
- Monofocal fixed-focus lens – This is the most conventional type of intraocular lens (IOL). It has an even refractive power. The lenses provide sharpest vision only at a single focal point. They are available in spherical and aspheric shapes. Aspheric IOLs are the more advanced of the two. They resemble the natural lens, offering better contrast sensitivity and night vision. Most individuals will still require reading glasses for up-close tasks.
- Accommodating IOLs – These are a type of monofocal. They contain flexible haptics which hold them in place inside the eyes. The haptics allow movement of the lenses. When one looks at a near object, they move forward slightly. As a result, the lenses are able to offer clear vision for varying distances.
- Toric IOLs – These are another variety of monofocals. These have different powers in some regions of the lens. They are used to correct astigmatism.
- Multifocals – They differ from monofocals in that they have different optics which allow separate areas in focus. They focus clearly on objects of varying distances.
- Monovision – This is a technique where lenses of differing refractive power are inserted in the eyes. One eye is corrected for far-away vision while the other is modified for near vision. Traditional monofocals are used for this. When other advanced intraocular lenses are used, the term ‘modified monovision’ is used.
- The patient should remove contact lenses before surgery and avoid wearing makeup. Patients should also make arrangements to be driven back home.
The surgery is performed on an outpatient basis. The phacoemulsification method is used to extract the lens. The surgeon numbs the eye then makes a tiny incision. A vibrating hollow needle (ultrasound probe) is used to emulsify the lens. The emulsified lens is vacuumed out of the lens via the hollow center of the probe. Afterwards, a fluid is simultaneously infused to keep eye inflated. The new lens is then folded and inserted into the capsular bag.
The process takes about half an hour. Each eye is operated on separately. The interval for this is about a week or so. No stitching is necessary in this surgery as the eye heals on its own.
After care, recovery, results
The prognosis of the surgery is usually favorable. After one or two days, the patient can go back to normal activities such as driving. However, healing may take slightly longer. Blurry vision, halos, and glare may also be present in the beginning but they soon go away.
The eye doctor may issue a contact lens for the unoperated eye after the first surgery. Antibiotics, anti-inflammatories and pain medication may be prescribed where necessary. The patient should go for routine check ups to monitor progress.
Risks & complications
Just like in cataract surgery, a few complications may occur. These are:
- Dislocated lens
- Infections and hemorrhage
- Retinal tears
- Ocular hypertension
- Droopy eyelid (ptosis)
- Glare and halos around lights