Laser Blended Vision – Corrective Laser Eye Surgery For Presbyopia

Prof Dan Reinstein from the London Vision Clinic explains presbyopia and how this can be successfully treated and corrected by Laser Eye Surgery – Laser Blended Vision. Further, he compares different, old and new, corrective refractive eye surgery treatments – Monovision,  Multifocal and Laser Blended Vision.

[media id=225 width=640 height=480]Prof Dan Reinstein from the London Vision Clinic explains presbyopia in a video and how this can be successfully treated and corrected by Laser Eye Surgery

Professor Reinstein On The Challenge Of Correcting Presbyopia

Correction of refractive error should no longer be considered the only aim of refractive surgery, as almost any refractive error can now be corrected fully. The final refractive surgical frontier is the challenge of correcting presbyopia. The two main surgical approaches to correcting presbyopia are – monovision and multi focality. The first attempt to create a multifocal cornea using an excimer laser was by Meditec in 1991 using the MEL60 excimer laser.

Professor Reinstein On Monovision And Multifocal Presbyopic Correction

A small superior zone was intended for near, while the majority of the profile was intended for distance.  Since then other multifocal ablation profiles have been used, such as creating a central area for distance vision with a mid peripheral area for near vision, or steepening a central area for near vision leaving the mid periphery for far vision.

Multifocal had accommodative intraocular lenses have also been designed and are being used, but while an overall improvement in visual acuity at distance and near has been recorded for both multi focal ablation profiles and multi focal UILs, safety and quality of vision have been compromised to some extent.

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The underlying problem with any multifocal presbyopic correction is that the brain is not wired to interpret multiple images in the same eye and so there is often a very long narrow adaptation period required.  On the other hand, the brain has been naturally programmed for millions of years for binocular vision to suppress the blur from one eye or the other, which is why monovision is naturally tolerated by many patients.

The amount of induced myopia (short-sightedness) required in the near eye increases with age (ageing eyes), which increases the cross blur perceived, decreasing patient tolerance, increasing distance blur and compromising intermediate vision.

Contact a Patient Care Coordinator at 0207 224 1005 to discuss what results you can expect to achieve.

Professor Reinstein On The Ideal Laser Eye Surgery Technology

Here we present specialised MEL8o non-linear aspheric ablation profiles designed to increase the depth of field and implemented together with a new micro mono vision protocol based on the principle of mono vision. In presbyopia, the loss of accommodation means that the near vision in both eyes becomes blurred, leaving the patient needing reading glasses.

The ideal solution would be to able to increase the depth of field of each eye, so that each eye could see clearly at distance, intermediate and near. So far the non-linear aspheric profiles have been shown to increase the depth of field but not enough to give the patient clear vision as all distances, far to near.

Contact a Patient Care Coordinator at 0207 224 1005 to discuss what results you can expect to achieve.

Professor Reinstein On The Best Patient Solution

In order to give the patient good reading vision the non-dominant eye is slightly shifted towards myopia.

This results in one eye:

  • being clearly focused for near vision but only slightly blurred at distance
  • and another being clearly focused for distance vision but only slightly blurred at near.

The increased depth of field in each eye means that there is a region where the range of clear vision overlaps, known as the blend zone, the result is that good binocular near, intermediate and distance vision can be achieved with a lower degree of anisometropia than traditional monovision, which we refer to as micro monovision.

Therefore, much less suppression is required and there is no disassociation between the eyes. In tradition monovision the depth of field at each eye is comparatively smaller meaning that the near eye needs to be more myopic for the patient to read comfortably and leaving a gap between the range of vision of the two eyes.

This replaces the intermediate blend zone with a blur zone. This makes traditional monovision much less tolerated than Laser Blended Vision. 

60% Of Patients Tolerate Monovision – 97% Laser Blended Vision

Published reports found that traditional monovision was tolerated by about 60% of patients, whereas Laser Blended Vision where the relative blurring in each eye is reduced has been found to be tolerated by about 97% of patients.

Prof Dan On Laser Blended Vision Laser Eye Surgery

The surgery itself is identical to a standard Lasik procedure, so the risks are very low compared to producing surgical pseudophakia.

In this example the flap is created using the Visumax femosecond laser.

  • 1. Suction is applied to the cornea and the pressure is low enough for the patient to see throughout the procedure.
  • 2. The bubble layer is created from outside to in, so that the patient can fixate on the flashing light taking about 20 seconds to complete the flap. The Visumax automatically centres the flap on the pupillary reflex.
  • 3. The flap is then lifted by separating the bubble layer, the ablation is carried out, and the flap is replaced.

In a prospective study for both myopic treatments up to -8.5 diopters and hyperopic treatments up to 5.75 diopters, the combined distance and near binocular visual outcomes were found to be excellent. 98% of myopic patients could see 20/20 at distance and read J5, which is newsprint, at near. 95% of hyperopic patients could see 20/20 at distance and read J5 at near.

The fusion between the two eyes was confirmed by the finding that binocular distance vision was statistically significantly better than the monocular distance vision of the distance eye alone.  This demonstrates the presence of neural summation between the images from the two eyes despite the relatively blurred distance image in the near eye.

Professor Reinstein On Laser Blended Vision Treatment Results

To illustrate the increase in depth of field the near eye’s in the hyperopic (long-sighted) group had a mean refraction of -1.32 diopters, so one would expect the mean uncorrected distance vision to be about 20/70.  Actually, it was 20/44, better than expected, corresponding to a nominal distance refraction of only -0.85.

For the near vision an average add of 2.25 would be required given the average age of 56.  However, the patients were able to comfortably read newsprint with an add of only -1.32 diopters.  This range demonstrates an effective depth of field of 1.4 diopters.

Find out more about the various eye conditions that can be treated with Laser Eye Surgery at the London Vision Clinic.

The use of non liner aspheric profiles that increase the depth of field of each eye enables the difference between the eyes to be greatly reduced, increasing tolerance, providing continuous good vision from near through intermediate, to distance objects and all this using standard extra ocular Lasik surgery, optimising both patient satisfaction and surgical safety.

Prof Reinstein Explains Presbyopia And Compares Refractive Laser Eye Surgery With Other Corrections [video]