Laser blended vision

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Laser blended vision
Specialty Ophthalmology

Laser blended vision is a laser eye treatment which is used to treat presbyopia (ageing eyes; [1] progressive loss of the ability to focus on nearby objects) or other age-related eye conditions. [1] 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.

Contents

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. [2] 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, [3] 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)., [4] [5]

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. [5] [6] 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. [7] 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 [8] 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. [9] 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). [10] [11]

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 [12] also allows for ensuring the eyes can work together to create the Laser Blended Vision effect.

Unlike with monovision surgery where it is generally advised to perform a "monovision contact lens trial", [13] Laser Blended Vision screening does not incorporate this as it would automatically exclude many suitable candidates from having the procedure. This is because a much larger proportion of people are suitable for Laser Blended Vision (>95%) [14] than monovision (59-67%). [3]

During Surgery and Post Operative

During the surgery, a corneal flap is created, during which there can be a sensation of slight pressure on the eye during the procedure.

The non-dominant eye is covered and the dominant eye is opened and kept open by a speculum, the corneal flap is lifted and the laser correction is done – an ultra thin flap can be created for treatment of very high prescriptions. [15] The flap is replaced and the speculum is removed. The dominant eye is treated next. The software data for each eye is stored in the Carl Zeiss Meditc MEL 80 laser [16] and delivered by the eye-tracker controlled computer generated excimer laser pulses. The laser time for each eye is usually under 30 seconds. The dominant eye is mainly corrected for distance and intermediate vision and the non-dominant eye is corrected for intermediate and near vision, by increasing the depth of focus for each eye.

The entire procedure takes approximately 20 minutes for both eyes and the visual recovery is rapid and there is very little discomfort afterwards, usually described as if contact lenses had been left in for too long. The flap seals down usually within a few hours and the early postoperative recovery period usually about 7 days during which care is needed to not rub eyes and to wear eye shields during the night. The results are almost instantly available to the patient, where objects and people will seem more in focus, and most people can return to work the next day after their postoperative day 1 check.

Suitability of treatment

Laser blended vision treatment is suitable for people with presbyopia. People mostly develop presbyopia, refractive error between the ages of 40 and 45 years. As we age, the natural lens inside the eye grows, leading to a decrease in the ability of the eye to change its focus from distance to near, a process called accommodation (accommodation (eye)). There is still much controversy amongst experts as to the mechanism of accommodation of the eye, which is probably why the actual reversal of presbyopia is still not medically possible.

Laser Blended Vision is suitable in general for anyone with presbyopia who is also a candidate for corneal laser eye surgery; the range of preoperative prescriptions that can be treated varies, but results have been published for laser blended vision using the Carl Zeiss Meditec MEL80 excimer laser for myopia (short-sightedness) up to -8.50D with astigmatism, [17] hyperopia (long-sightedness) up to +6.00D with astigmatism [18] and for patients who have emmetropia (good distance vision) but only need reading glasses for computers or near vision. [14]

Laser Blended Vision can also be performed after cataract surgery in order to increase the independence from spectacles. Similarly, cataract surgery can be performed together with Laser Blended Vision to provide a patient with better spectacle independence than can be afforded by simple monovision and without the decrease in quality of vision that is produced by a Multifocal intraocular lens. Multifocal intraocular lenses work by splitting the light entering the eye into different focal planes, hence resulting in an eye that never achieves 100% of light at distance or near, however these are increasingly commonly employed for the correction of presbyopia. [9]

Treatment results

Patients treated using Laser Blended Vision, have an increased depth of field compared to traditional monovision. [2] [19] With use of contact lens monovision there is a diminishing effect on distance vision, depth of field and contrast sensitivity (neural subtraction) [20] which is not seen with Laser Blended Vision; in fact Laser Blended Vision has been shown to provide better distance vision binocularly than with the dominant distance eye alone (neural summation). [14] [17] [18] According to a comprehensive review of the medical literature conducted by Dr. BJ Evans, [21] only 59-67% of patients are tolerant to mono vision, compared to the tolerance to Laser Blended Vision in more than 95% of patients screened and treated. [14]

A year after Laser Blended Vision LASIK, approximately 95% of patients achieved 20/20 vision at distance while able to read newsprint type size at near. [4] [22]

Limitations and potential complications

The aim of this surgery is to produce one eye that sees mostly at distance, but still at near and the other eye that sees mostly at near, but also at distance. There is a period of adaptation to Laser Blended Vision which varies from a few weeks to up to a year; according to a study published in the Journal of Refractive Surgery by Professor Dan Reinstein and colleagues, the average patient is adapted within three months of treatment, and at one year 3% were not yet fully adapted. [14] During adaptation patients may feel that the distance vision is strange, and this can produce some slight dizziness or visual discomfort in the initial phases for which a pair of glasses that reverse the difference between the eyes are prescribed.

The risks and complications of Laser Blended Vision are identical to those of LASIK laser eye surgery as such. Laser Blended Vision does not carry specific increased serious risks relative to the standard LASIK laser eye surgery itself. As with all laser eye procedures, patients must familiarize themselves with the risks and side effects of the treatment, which is best done in consultation with an expert laser eye surgeon who performs the Laser Blended Vision procedure as a routine in his practice.

Because of the improved control of induced spherical aberration [2] the excimer laser employing Laser Blended Vision software enables treatment of higher levels of myopia without removing high amounts of corneal tissue,. [23] After the procedure, artificial tears and antibiotic eye drops are used for at least a week which can cause temporary blurred vision and irritation. The sensation of dryness of the eyes is a common side-effect of LASIK and can be uncomfortable for anywhere from a few weeks to a few months after the surgery; most patients use artificial tears for this period of time after LASIK.

Presbyopia is not reversed by Laser Blended Vision, which is a highly effective treatment but not a cure and as presbyopia is a progressive condition, a boost may be required some years after treatment. Typically the effects of Laser Blended Vision surgery last between 5 and 10 years and most patients are able to have an enhancement procedure to recover the benefits of the initial procedure.

Related Research Articles

<span class="mw-page-title-main">Farsightedness</span> Eye condition in which light is focused behind instead of on the retina

Far-sightedness, also known as long-sightedness, hypermetropia, and hyperopia, is a condition of the eye where distant objects are seen clearly but near objects appear blurred. This blur is due to incoming light being focused behind, instead of on, the retina due to insufficient accommodation by the lens. Minor hypermetropia in young patients is usually corrected by their accommodation, without any defects in vision. But, due to this accommodative effort for distant vision, people may complain of eye strain during prolonged reading. If the hypermetropia is high, there will be defective vision for both distance and near. People may also experience accommodative dysfunction, binocular dysfunction, amblyopia, and strabismus. Newborns are almost invariably hypermetropic, but it gradually decreases as the newborn gets older.

<span class="mw-page-title-main">LASIK</span> Corrective ophthalmological surgery

LASIK or Lasik, commonly referred to as laser eye surgery or laser vision correction, is a type of refractive surgery for the correction of myopia, hyperopia, and an actual cure for astigmatism, since it is in the cornea. LASIK surgery is performed by an ophthalmologist who uses a laser or microkeratome to reshape the eye's cornea in order to improve visual acuity.

<span class="mw-page-title-main">Presbyopia</span> Medical condition associated with aging of the eye

Presbyopia is physiological insufficiency of accommodation associated with the aging of the eye that results in progressively worsening ability to focus clearly on close objects. Also known as age-related farsightedness, it affects many adults over the age of 40. A common sign of presbyopia is difficulty reading small print which results in having to hold reading material farther away. Other symptoms associated can be headaches and eyestrain. Different people will have different degrees of problems. Other types of refractive errors may exist at the same time as presbyopia. This condition is similar to hypermetropia or far-sightedness which starts in childhood and exhibits similar symptoms of blur in the vision for close objects.

<span class="mw-page-title-main">Photorefractive keratectomy</span> Refractive eye surgery procrdure

Photorefractive keratectomy (PRK) and laser-assisted sub-epithelial keratectomy (LASEK) are laser eye surgery procedures intended to correct a person's vision, reducing dependency on glasses or contact lenses. LASEK and PRK permanently change the shape of the anterior central cornea using an excimer laser to ablate a small amount of tissue from the corneal stroma at the front of the eye, just under the corneal epithelium. The outer layer of the cornea is removed prior to the ablation.

<span class="mw-page-title-main">Eye surgery</span> Surgery performed on the eye or its adnexa

Eye surgery, also known as ophthalmic surgery or ocular surgery, is surgery performed on the eye or its adnexa. Eye surgery is part of ophthalmology and is performed by an ophthalmologist or eye surgeon. The eye is a fragile organ, and requires due care before, during, and after a surgical procedure to minimize or prevent further damage. An eye surgeon is responsible for selecting the appropriate surgical procedure for the patient, and for taking the necessary safety precautions. Mentions of eye surgery can be found in several ancient texts dating back as early as 1800 BC, with cataract treatment starting in the fifth century BC. It continues to be a widely practiced class of surgery, with various techniques having been developed for treating eye problems.

<span class="mw-page-title-main">Radial keratotomy</span> Refractive surgical procedure to correct myopia (nearsightedness

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<span class="mw-page-title-main">Refractive surgery</span> Surgery to treat common vision disorders

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<span class="mw-page-title-main">Intraocular lens</span> Lens implanted in the eye to treat cataracts or myopia

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<span class="mw-page-title-main">Phakic intraocular lens</span> Lens implanted in eye in addition to the natural lens

A phakic intraocular lens (PIOL) is an intraocular lens that is implanted surgically into the eye to correct refractive errors without removing the natural lens. Intraocular lenses that are implanted into eyes after the eye's natural lens has been removed during cataract surgery are known as pseudophakic.

Automated lamellar keratoplasty (ALK), also known as keratomileusis in situ, is a non-laser lamellar refractive procedure used to correct high degree refractive errors. This procedure can correct large amounts of myopia and hyperopia. However, the resultant change is not as predictable as with other procedures.

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<span class="mw-page-title-main">Gholam A. Peyman</span> Iranian-American ophthalmologist and retina surgeon known for inventing LASIK eye surgery

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The eye, like any other optical system, suffers from a number of specific optical aberrations. The optical quality of the eye is limited by optical aberrations, diffraction and scatter. Correction of spherocylindrical refractive errors has been possible for nearly two centuries following Airy's development of methods to measure and correct ocular astigmatism. It has only recently become possible to measure the aberrations of the eye and with the advent of refractive surgery it might be possible to correct certain types of irregular astigmatism.

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References

  1. 1 2 "Eye health: Presbyopia and your eyes". Boots WebMD. WebMD LLC. Archived from the original on 2018-03-05.Eye health: Presbyopia and your eyes.
  2. 1 2 3 Gifford P, Kang P, Swarbrick H, Versace P (September 2014). "Changes to corneal aberrations and vision after Presbylasik refractive surgery using the MEL 80 platform". Journal of Refractive Surgery. 30 (9): 598–603. doi:10.3928/1081597X-20140709-01. PMID   25019353.
  3. 1 2 Evans BJ (September 2007). "Monovision: a review". Ophthalmic & Physiological Optics. 27 (5): 417–39. doi: 10.1111/j.1475-1313.2007.00488.x . PMID   17718882.
  4. 1 2 Non-linear aspheric ablation profiles for presbyopic LASIK using the MEL80 and CRS Master Laser Blended Vision module. Dan Z. Reinstein, Timothy J. Archer, Marine Gobbe. In: Lucio Buratto, Editor: LASIK: The Evolution of Refractive Surgery. Thorofare, NJ: SLACK Incorporated, October 2011
  5. 1 2 What is Laser Blended Vision? Cons and Pros. LaserReviews.co.uk http://www.lasikreviews.co.uk/laser-vision-correction-lasik-blended.htm
  6. ↑ Presbyond Laser Blended Vision: Another approach to presbyopia. Dan Z. Reinstein. Eyeworld January 2013. http://www.eyeworld.org/article-presbyond-laser-blended-vision---another-approach-to-presbyopia Archived 2014-08-21 at the Wayback Machine
  7. ↑ Boxer Wachler, Brian S (August 2017). "The LASIK Procedure: A Complete Guide". AllaboutVision. AAV Media LLC.
  8. ↑ Boxer Wachler, Brian S (September 2017). "Refractive Lens Exchange (Lens Replacement Surgery)". AllaboutVision. AAV Media LLC.
  9. 1 2 Thompson, Vance (September 2016). "Multifocal Intraocular Lenses: ReSTOR And Tecnis Multifocal IOL". AllaboutVision. AAV Media LLC.
  10. ↑ Boxer Wachler, Brian S (August 2017). "LASIK Enhancement: When Additional Surgery Is Needed". AllaboutVision. AAV Media LLC.
  11. ↑ Advantages of LASIK Surgery
  12. ↑ Tong, Frank; Blake, Randolph (2008). "Binocular rivalry". Scholarpedia. 3 (12): 1578. Bibcode:2008SchpJ...3.1578B. doi: 10.4249/scholarpedia.1578 .
  13. ↑ Boxer Wachler, Brian S (February 2018). "Surgery For Presbyopia". AllaboutVision. AAV Media LLC.
  14. 1 2 3 4 5 Reinstein DZ, Carp GI, Archer TJ, Gobbe M (August 2012). "LASIK for presbyopia correction in emmetropic patients using aspheric ablation profiles and a micro-monovision protocol with the Carl Zeiss Meditec MEL 80 and VisuMax". Journal of Refractive Surgery. 28 (8): 531–41. doi:10.3928/1081597X-20120723-01. PMID   22869232. S2CID   46555346.
  15. ↑ Accuracy and reproducibility of Artemis central flap thickness and visual outcomes of LASIK with the Carl Zeiss Meditec Visumax Femtosecond Laser and the MEL 80 Excimer Laser platforms. Journal of Refractive Surgery 2010, Feb 26: 107 – 19. DZ Reinstein, TJ Archer, M Gobbe, N Johnson.
  16. ↑ Carl Zeiss Meditec AG (2010) "MEL80 Excimer Laser high performance meets versatility" Publicis v/2010 No. 0000001838386, Germany, USA.
  17. 1 2 Reinstein, Dan Z.; Archer, Timothy J.; Gobbe, Marine (2011). "LASIK for Myopic Astigmatism and Presbyopia Using Non-Linear Aspheric Micro-Monovision with the Carl Zeiss Meditec MEL 80 Platform". Journal of Refractive Surgery. 27 (1): 23–37. doi:10.3928/1081597X-20100212-04. ISSN   1081-597X. PMID   20205360.
  18. 1 2 Reinstein DZ, Couch DG, Archer TJ (January 2009). "LASIK for hyperopic astigmatism and presbyopia using micro-monovision with the Carl Zeiss Meditec MEL80 platform". Journal of Refractive Surgery. 25 (1): 37–58. doi:10.3928/1081597X-20090101-07. PMID   19244952.
  19. ↑ LASIK for myopic astigmatism and presbyopia using non-linear aspheric micro-monovision with the Carl Zeiss Meitec MEL 80 Platform. Journal of Refractive Surgery, Available at www.journalofrefractivesurgery.com/preprint.asp Posted online March 11, 2010, Dan Z. Reinstein, Timothy J. Archer, Marine Gobbe
  20. ↑ The effect of different monovision contact lens powers on the visual function of emmetropic presbyopic patients (an American Ophthalmological Society thesis). Durrie DS. Trans Am Ophthalmol Soc. 2006;104:366-401.
  21. ↑ Monovision: a review. Ophthalmic Physiol Opt. 2007;27:417-439
  22. ↑ "LASIK OKC". Tuesday, 15 December 2020
  23. ↑ Corneal ablation depth readout of the MEL80 Exicmer Laser compared to Artemis three-dimensional very high-frequency digital ultrasound stromal measurements. Journal of Refractive Surgery Available www.journalofrefractivesurgery.com/preprint.asp. Posted online January 28, 2010. Dan Z Reinstein, Timothy J Archer, Marine Gobbe.
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