2010, the year when 20/10 vision for everybody was once promised

Several years ago in different ophthalmic conferences some people was convinced that around the year 2010, supernormal vision (20/10 visual acuity) would be available for everybody. I remember you were among the not so optimistic (or more realistic) at the time. What actually happened? Are we ready for 20/10 vision? Raymond, Birmingham, UK

As usual, I received this question several months ago, and then I knew this should be my last entry for 2009, at the doorsteps of 2010! Thanks Ray!

As those following these pages know well, vision is first limited by the quality of the retinal image (given by the eye’s optics) and then by the retinal mosaic and the posterior neural processing. The human eye is a paradigmatic example of a simple optical instrument providing exceptional functionality. Despite its simplicity, only composed of two lenses, the cornea and the crystalline lens, the quality of the retinal images produced by the eye has a tremendous impact in vision. A poor optics means a poor vision and as a consequence a low quality of life. In the 70’s of the last century, the idea that everything was known from the eye’s optics prevailed. A somehow rudimentary approach based in the knowledge for the XIX century was widely used by practitioners. Although it was well recognized from the time of Helmholtz that the optical quality of the normal eye could be affected by optical aberrations, few researchers and virtually none clinician were quite interested in those aspects. The complexities of the eye optics were not known and this lack of understanding severely limited the success of ophthalmic correction devices and surgery procedures. In the last decades of the XX century, pioneer scientists developed new instruments to evaluate the eye’s image quality (for instance, we registered the first the retinal image of a point source from a laser beam with a video camera using the double-pass technique; Santamaria, Artal and Bescos, JOSAA, 1987). Many of these ideas and instruments were transferred from the lab to the clinic in the 90’s. And hundreds of ophthalmologists in the world started to use routinely instruments to measure and control the quality of the ocular optics. The availability of new technology to measure the eye’s aberrations and its combined used with laser refractive procedures actually produced a great enthusiasm to see in the near future all or most of the eye’s aberrations corrected. By using adaptive optics, we already knew that after correction of the eye’s aberrations, subjects could have better vision, in some cases around 20/10 or even higher! So at the time (early 2000) many people firmly believed that with some additional fine tuning of lasers and wavefront technology, virtually every patient could achieve 20/10 vision after appropriate surgery. And then the sentence: “20/10 vision in 2010” was readily disseminated.
Visual acuity is defined as the inverse of the smallest detail that can be resolved. For example, if you manage to see a letter E with a size subtending one minute of arc (approximately a letter of 1 cm placed at around 6 m), your visual acuity would be 1/1=1 (or 20/20). At the same distance if you could read a letter with half the size, your visual acuity would be 2/1 (20/10). Some subjects have naturally this type of excellent visual acuity, however, most people have a visual acuity around 20/20 and 20/15. See previous post: http://pabloartal.blogspot.com/2008/10/optical-quality-of-eye-in-subjects-with.html

Laser refractive procedures, although in general successfully correct defocus, (myopia and hyperopia) and astigmatism tend to induce higher order aberrations. This leads typically to normal or mediocre visual acuity. In the last years, improvements in technology (laser systems, ablation profiles, wavefront control, etc…) allowed to produce better visual outcomes, but not a systematic correction of all aberrations and unfortunately not 20/10 vision yet!

A different debate is if we really need 20/10 vision after some type of aberration correction. My personal point of view is more conservative. I would like to have every surgical procedure basically providing patients with normal eye’s optics rather than perfect one.  As I discussed here before, some normal level of aberrations may  help for a good vision (for driving accommodation, avoiding sub-sampling phenomena, etc…). It is however possible (I can dedicate a future post to this issue) that some particular aspects of vision could be improved with proper eye's correction.  

A typical approach is to measure the eye’s aberrations, expressed as a series of Zernike polynomials and correct some of them. As an example of how many polynomials would be required to actually capture fine details, have a look of the picture below (prepared by Pedro Prieto). It is the name of our lab (LOUM) reconstructed with an increasing number of Zernike polynomials. Even with more than 200 polynmials... the letters cannot be recognized!

2010 is nearly here (one more day left of 2009), and we can clearly say that ophthalmologists cannot offer 20/10 vision to every patient. This is not a failure. In the last decade advances in the science  technology and clinical procedures were exceptional and patients will for sure benefit for all of that. BUT, I have to say, that I will be even happier if doctors all over the world could offer simply 20/20 vision to every patient in 2020!!!

I would like to propose a new motto: "In 2020, 20/20 vision for everybody in every country"

After a really warm fall in the Murcia area with nearly summer temperatures until well into December, in the last weeks, we had some unusual cold weather (only a few days, though…). And even snow was very close to the city. See this nice picture of Sierra Espuña, a few Km south of Murcia city. The picture was taken by Antonio Benito.

I wish all of you the best for next year 2010, even if you do not have 20/10 visual acuity!

 

Santamaria, Artal, Bescos (1987). Determination of the point spread function of human eyes using a hybrid optical-digital method J.Opt.Soc.Am.A., 4