Laser blended vision is a sophisticated laser eye treatment which is used to treat presbyopia (ageing eyes; progressive loss of the ability to focus on nearby objects) or other age-related eye conditions. It can be used to help people that simply need reading glasses, and also those who have started to need bifocal or varifocal spectacle correction due to ageing changes in the eye. It can be used for people who are also short-sighted (myopia) or long-sighted (hyperopia) and who also may have astigmatism.
Primarily the treatment is for a condition called presbyopia. Laser Blended Vision can be achieved through laser eye surgery, usually performed as LASIK, although surface laser eye surgery PRK or LASEK can be used to produce the effect. Laser Blended Vision works by increasing the depth of field of each eye through subtle changes in the optics of the corneal spherical aberration. The increase in depth of field allows for the eyes to be corrected in such a way that the dominant eye is set for distance and intermediate vision while the non-dominant eye sees best in the intermediate to near range. Because of the similarity in the visual performance of each eye in the intermediate range the brain is able to fuse the images between the eyes rendering a binocular visual environment. This is in contradiction to traditional monovision where the image disparity between the eyes is too high for image fusion by the brain and instead the brain needs to apply suppression of the blurred eye in order to perceive a clear visual field. In Laser Blended Vision, the eyes are effectively working together to allow good vision at near, intermediate and far, without the use of glasses. The effects of Laser Blended Vision tend to last between 5 and 10 years but can be further adjusted by enhancement procedures.
Advantages of treatment
Laser blended vision provides a range of benefits, particularly in comparison to traditional monivision solutions, such as bifocal glasses or contact lenses.
The key advantage of Laser blended vision is the freedom from reading glasses. Between 95% and 98% of Laser Blended Vision patients can read normal newsprint and between 80% and 96% can read the very smallest print on medicine bottle inserts (J1 or N4 print size).,
There is a creation of intermediate and far-intermediate distance zone of binocular fusion, allowing the merging of images from each eye in the brain so no dissociation occurs between the eyes as with monovision. Due to increased depth of field in both eyes, the distance vision is significantly better than would otherwise be anticipated.
Laser Blended Vision is a shape profile modification to the standard excimer laser eye surgery method that has been performed tens of millions of times worldwide, mostly as LASIK. LASIK provides a very high level of safety particularly when employing femtosecond laser flap creation (IntraLASIK) and eye tracker technology that tracks eye position at a feedback frequency significantly higher than the repetition rate of the excimer laser pulses themselves.
Over the last ten years, refractive clear lens exchange has become a more common procedure for correcting presbyopia. Refractive clear lens exchange is basically the same surgery as that was previously only designated for eyes with visually impairing cataract, however it is now performed in eyes without cataract (i.e. a clear lens) for the purposes of gaining independence from glasses. A significant advantage of Laser Blended Vision is that it does not involve a surgery that requires entering the inside of eye, a requirement for all other intraocular lens alternatives that involve either intraocular lens monovision or the use of multifocal intraocular lenses. In contrast, Laser Blended Vision is generally more accurate at hitting the refractive target than intraocular lenses, and if target is not achieved, it is adjustable by a simple enhancement procedure (again, without entering the eye).
Procedure
Preoperative screening
During the preoperative screening, a complete examination of the eye is carried out at a consultation with the surgeon to determine if a patient is suitable for Laser Blended Vision treatment. The dominant eye is determined and vision tested to identify the level of correction required for distance and near on the dominant eye and non-dominant eye. The analysis of ocular dominance and patient specific interocular suppression and binocular rivalry also allows for ensuring the eyes can work together to create the Laser Blended Vision effect.