Refractive Lens Exchange
Also known as PreLex (presbyopic lens exchange) or Clear lens extraction, refractive lens exchange is the procedure of choice where both laser eye surgery and implantable contact lens surgery are not indicated such as patients who have early lens changes/early cataract or who are too far sighted to make the other treatments safe and effective.
Allon Barsam uses premium lens implants such as toric intraocular lenses or presbyopic lenses, to correct astigmatism, which can give a person both distance and reading vision simultaneously with the use of a multifocal intraocular lens. He also has considerable experience with combinations of these options, such as with the use of the multi-focal toric lens. Mr Barsam can carry out his refractive lens exchange surgery manually or with the use of a femtosecond laser and was the first British Ophthalmologist in the world to do so.
REFRACTIVE LENS EXCHANGE SURGERY
Refractive lens exchange eye surgery is the removal of the crystalline lens and implantation of a high definition Intraocular Lens into the capsular bag. This allows Mr Barsam to correct and therefore eliminate myopia – short-sightedness, hypermetropia – far-sightedness and presbyopia – reading vision problems. Refractive lens exchange is most commonly performed in the context of premium cataract surgery, when opacification of the crystalline lens causes visual symptoms and a reduction in vision. However, this lens replacement surgery can be used in the absence of cataract where laser eye surgery is not suitable.
TYPES OF LENS IMPLANTS USED
Historically, conventional intraocular lenses corrected only spherical refractive error (myopia and hypermetropia) and introduced some degree of spherical imperfection to the eye, resulting in a reduction in the quality of vision. Premium intraocular lens implants, as used in refractive lens exchange, possess additional refractive properties above conventional monofocal intraocular lenses (IOLs). These IOLs typically use the same platform (i.e. biomaterial, optic size and haptic design) as conventional monofocal IOLs and the additional refractive properties are specially built onto one surface of the IOL optic.
MULTIFOCAL and TRIFOCAL IOLs
Multifocal IOL and Trifocal IOL optics are divided into zones which are focused for distance and nearness respectively. The most modern, technologically advanced lens options allow for a very high degree of independence from spectacles.
Toric IOLs correct astigmatism as well as myopia and hyperopia. They need to be implanted in the correct position corresponding to the area of greatest corneal curvature.
IC-8 PINHOLE IOL
Allowing only focused light to enter the eye, the new IC-8 lens utilises a pinhole design and provides users with additional freedom from glasses for far, intermediate and near distance.
ION BLENDED VISION
This involves using IOLs to correct the dominant eye for perfect infinity distance vision and the non-dominant eye for reading/intermediate. Customising the optics of the lens choice to the natural aberrations (imperfections) of a patient’s eye allows the lenses to work together to make patients independent of glasses for all activities except close reading.