The year is 2000, we have just entered the new millennium and look with hope to the future. We survived the potential threat of the millennium bug that was predicted to cause so much chaos on the stroke of midnight on the December 31, 1999. There was a sigh of relief and a welcome anti-climax as the world did not enter an apocalypse, but so much was the unknown threat of the millennium bug that the UK government posted guidance leaflets to every home (figure 1) to educate and guide us. We are now safely into the new millennium, the year 2000! To celebrate this milestone almanac event, various invited authors wrote a supplement for Optician magazine called ‘Vision 2020’ as that was going to be a big year in the ophthalmic world (little did we know of the global pandemic that would affect us). The papers prophesied what the ophthalmic world would be like in 2020 on the topics of:
- The consulting room of the future
- In search of the ultimate contact lenses
- Lenses for the new millennium
- The future of surgical correction
- Frames of the future
I was invited to write the paper on the future of surgical correction, as I was in the middle of my PhD related to laser vision correction (LVC).1 In the year 2000 we were in the middle of the LVC boom. The two largest LVC clinics in the UK were Optimax and Ultralase, and the newer ones were Boots Laser Eye Clinics and Maxivision. There were of course many consultant ophthalmologists offering LVC at their own clinics or using facilities of other clinics. Maxivision and Boots laser eye clinics were later acquired by Optical Express and Ultralase was acquired by Optimax, but the last 20 years has seen the proliferation of many new national LVC clinic providers and more independent consultant ophthalmologists offering the LVC too.
In my original article I predicted that intrastromal rings and implantable contact lenses (phakic intraocular lenses) would be a fading memory. Today we still have intrastromal rings, but they are used primarily as a surgical option in patients with keratoconus, with the aim of trying to flatten the cone to a less irregular shape so the patient can return to contact lens use or maybe spectacles. Phakic intraocular lenses are still around and remain popular in some countries but less so in the UK where there is a preference for performing clear lens extractions for higher refractive errors or in older presbyopic patients. We may see a new rise in the popularity of phakic intraocular lenses since they are now available with multifocal designs. Corneal implants remain, again with limited appeal but we have, over the last few years, seen interesting attempts to correct presbyopia with lens implants that change the curvature of the cornea, or create a diffractive ring pattern, or even employ pinhole optics that improve the depth of focus (figure 2).2
Figure 2: The KAMRA corneal inlay lens with its pinhole optics to improve depth of focus
I predicted that lasers used in LVC would improve and they certainly have.3 We do see smoother ablation profiles and faster repetition rates in the excimer lasers that can link to wavefront technology and attempt to minimise higher order aberrations. We have also seen the end of thermokeratoplasty, although there was a short-lived attempt to revive it using conductive keratoplasty (figure 3). Conductive keratoplasty utilised a non-contact device using radio waves, causing a thermal burn to around 75% corneal depth.4
Figure 3: A schematic view of the cornea showing the pattern used for conductive keratoplasty
I suggested a flapless LVC procedure using a solid-state laser, which has not happened, although the solid-state femtosecond lasers are very much a tool of choice for the modern refractive surgeon. The flapless procedure using intrastromal laser ablation may still happen in the future.5 Some laser manufacturers have introduced solid-state lasers to replace the excimer laser.6 The biggest innovation in the laser technology was probably the introduction of femtosecond lasers. Here is a device that could cut the flap in Lasik (laser-assisted in situ keratomileusis) surgery to a predictable depth and pattern without many of the complications of a microkeratome. The femtosecond laser was able to launch the new procedure, Smile (Small Incision Lenticule Extraction) surgery, as an alternative to LVC. This is very similar to one of the research procedures I described in my original paper that I had seen in a conference presentation.7 These new femtosecond lasers have made their way into cataract surgery and corneal graft surgery too. The latter being particularly useful in partial thickness keratoplasty such as anterior lamellar graft surgery or DSAEK (Descemet’s Stripping Automated Endothelial Keratoplasty). One of the more novel uses of the femtosecond laser was the Intracor technique, where concentric rings are created in the stroma of the non-dominant eye (figure 4). The resultant change in the cornea is to a slight central steepening which causes an increase in asphericity that increases the spherical aberration. The initial results were promising but the limitations included a slight reduction in distance vision and some reports of ectasia. It is also a modified monovision technique with the associated problems of loss of depth of focus.8
Figure 4: A cornea that had undergone Intracor femtosecond surgery
In terms of drug therapy, we have seen improvements in the medicines used, but we have not seen drugs being used to alter the shape or physiology of the lens or cornea. However, we have seen attempts with a femtosecond laser to soften the presbyopic crystalline lens and try to restore some of its malleability. Laser energy is applied to create a pattern of incisions within the crystalline lens tissue to split the lens fibres. This photo-disruption creates sliding planes that allow shape changing of the crystalline lens. Limitation in study designs were not able to explore long-term success but in the short-term at least the technique showed some interesting results (figure 5).
Figure 5: An eye after one hour and then one day post LENSAR lens softening surgery
When I wrote the article back in 2000 my remit was to be controversial, so some of the predictions were a little far-fetched. While the technology exists to remove the eye and replace it with a camera hard-wired to the visual cortex, this is not something that has been explored fully, and nor is it likely to be as an electiveprocedure. It is more likely to have low vision applications, rather than applications in refractive surgery. I think it would be fair to say that refractive surgery for presbyopia, although much improved, remains a Holy Grail since every current technique has some limitations. Scleral surgery for presbyopia might make a comeback as there are some initial promising results from LAPR (laser-assisted presbyopia reversal). The technique uses an infrared Erbium:YAG laser to apply ablations to the sclera, 0.5mm posterior to the limbus to 80% depth. However, the technique may have limitations as the patients develop more presbyopia and there may be some decrease in effectiveness with time due to changes in the scleral tissue. Multifocal and pseudo-accommodating intraocular lenses were not common in the commercial arena 20 years ago. There were some early research papers showing promise and over the past two decades these have dominated the landscape for surgery for presbyopia. We even saw the emergence of the light adjustable intraocular lens, which now has declined in popularity.9 Bifocal and trifocal intraocular lenses have also entered the market (figure 6) but the most exciting intraocular lenses are yet to appear. It is not hard to imagine a surgical technique where the presbyopic crystalline lens is removed a replaced with a flexible gel that mimics the properties of the natural lens in terms of flexure. A search on global patents will reveal that these ideas are in the planning stages. Studies have shown the innervation and vascular supply to be active in the ageing lens allowing the anatomy to remain working.10
Figure 6: The Oculentis M-Plus multifocal intraocular lens with a near add of +3.00 DS, with a sector shaped near vision segment
We have seen an increased predictability of refractive surgery techniques. Biometry has become more accurate and this was an essential factor in the growth of lens based refractive surgery. The use of artificial intelligence for outcome modelling has increased and we can expect that to continue to improve as we develop better instrumentation and gather more evidence to improve our machine learning algorithms. My remit 20 years ago was to be controversial, so let us end with something that would be deemed so. How about parts, or all, of the refractive surgery procedure, or cataract surgery for that matter, being automated? Could a machine cut the flap for LASIK, or apply the laser energy to create the ablation profile needed to correct the patient’s refractive error? Could a robot perform some of the tasks in cataract surgery, and therefore in clear lens extraction too? The global pandemic of 2020 has meant many ophthalmic practitioners offered at least part of their service though virtual means, which is surely something we will see an expansion of going forward. One instrument manufacturer suggested to me that he could envisage the ophthalmic practice of the future being more like a boutique where the patient went in to have automated diagnostic tests and checks followed by a virtual consultation with the practitioner. Could we imagine such a clinic where the patient has automated diagnostic tests and checks followed by a virtual consultant and consenting process, before an automated refractive surgery procedure, such as flap-less LVC? Does that sound far-fetched? Well ask yourself this, 20 years ago could you imagine an autonomous vehicle? It would be fair to say that we can expect the next 20 years to show an even steeper exponential growth in techniques and refinement of current procedures than we have over the past 20 years.
Shehzad Naroo is a reader at Aston University, editor-in-chief of Contact Lens and Anterior Eye and president of the International Association of Contact Lens Educators.
A PDF of the original Optician supplement published in 2000 can be accessed at http://fplreflib.findlay.co.uk/images/pdf/optician...
Acknowledgment
Professor Sunil Shah for reviewing this article and his support over the past 20 years.
References
- Naroo, S. A. (2000). “The future of the surgical correction.” Optician 219(5734-Supplement): S10-S11.
- Naroo, S. A. and P. S. Bilkhu (2016). “Clinical utility of the KAMRA corneal inlay.” Clin Ophthalmol 10: 913-919.
- Naroo, S. A. and W. N. Charman (2005). “Surface roughness after excimer laser ablation using a PMMA model: profilometry and effects on vision.” Journal of Refractive Surgery 21(3): 260-268.
- McDonald, M., J. Davidorf, R. K. Maloney, E. E. Manche and P. Hersh (2002). “Conductive keratoplasty for the correction of low to moderate hyperopia.” Ophthalmology 109(4): 637-649.
- Zhang, Z. Y., R. Y. Chu, X. T. Zhou, J. H. Dai, X. H. Sun, M. R. Hoffman and X. R. Zhang (2009). “Morphologic and histopathologic changes in the rabbit cornea produced by femtosecond laser-assisted multilayer intrastromal ablation.” Invest Ophthalmol Vis Sci 50(5): 2147-2153.
- Tsiklis, N. S., G. D. Kymionis, G. A. Kounis, A. I. Pallikaris, V. F. Diakonis, S. Charisis, M. M. Markomanolakis and I. G. Pallikaris (2007). “One-year results of photorefractive keratectomy and laser in situ keratomileusis for myopia using a 213 nm wavelength solid-state laser.” J Cataract Refract Surg 33(6): 971-977.
- Maatz, G. A., H. Hesiterkamp, H. Welling and W. Ertmer (1999). “Application of ultrashort laser pulses for intrastromal refractive surgery.” European Optical Society Topical Meeting on Physiological Optics 23: 84-85.
- Holzer, M. P., A. Mannsfeld, A. Ehmer and G. U. Auffarth (2009). “Early outcomes of INTRACOR femtosecond laser treatment for presbyopia.” J Refract Surg 25(10): 855-861.
- Hengerer, F. H., I. Conrad-Hengerer, S. E. Buchner and H. B. Dick (2010). “Evaluation of the Calhoun Vision UV Light Adjustable Lens implanted following cataract removal.” J Refract Surg 26(10): 716-721.
- Beebe, D. C. (2008). “Maintaining transparency: a review of the developmental physiology and pathophysiology of two avascular tissues.” Semin Cell Dev Biol 19(2): 125-133.