For several decades we have concentrated on making refractive surgery successful and this has involved ensuring procedures are safe, reliable, predictable and stable. The earliest refractive effect observed was the influence of lens couching in myopes who, the English ophthalmologist JT Woolhouse reported, did not require convex spectacles postoperatively.1
The first corneal refractive procedure was an astigmatic keratotomy by Schiotz2 in 1885 and later carefully studied systematically by the Dutch ophthalmologist Lans in 1896 where, in his thesis ‘Experimental studies of the treatment of astigmatism with non-perforating corneal incisions’, he described a variety of incisions and thermokeratoplasty to alter corneal shape.3
Today these procedures are still being used, albeit delivered with markedly different technology such as femtosecond laser. To quote from Ecclesiastes: ‘What has been will be again, what has been done will be done again; there is nothing new under the sun.’4
So where is refractive surgery heading? In predicting the future, it makes sense to look at population demographics, specifically age distribution. Over the next 10 years, ‘baby-boomers’ will be well and truly in the cataract generation and if they are going to need surgery and can afford to, they will be looking for ‘visual rejuvenation’.
Their children, the so-called ‘echo-boomers’, will have finally left home (in their 30s!) and be earning a decent living themselves. With more disposable income they will be looking for vision correction surgery and spectacle independence. By 2020 some of the echo-boomers will be entering the early presbyopic age and if they have not had refractive surgery already, they will be well motivated to have something done.
Role of the optometrist
Based on demographics, there is likely to be a phenomenal amount of surgery necessary for medical need alone. The role of the ophthalmologist and optometrist is going to change, with the ophthalmologist spending more time in the operating theatre doing surgery. Optometrists will routinely have to increase their scope of activity, involving themselves even more formally as members of the eye care delivery team. This will include refractive surgery.
This widening of activity will clearly evolve over time and education will be more intense. Use of technology will be pivotal, in particular for diagnostics.
Diagnostics
Diagnostic machines will become more compact and have multiple functionality. This is already taking place with the development of devices such as the Nidek OPD III (Nidek, Gamagori, Japan) which provides considerable information including refraction, keratometry, topography, overall aberrometry, internal and corneal aberrometry, pupil size and displacement, lens densitometry etc.
Integration with interferometers to measure axial length and expert software systems will provide information on the best refractive options available for each eye. This will be based on age, visual needs, lens status and ocular aberrometry. Not only will the best refractive option be provided but also the type of lens best suited optically to the individual or perhaps a planned bespoke laser ablative procedure.
Presently expert systems do not exist and instead ophthalmologists use their own expertise, based on knowledge, experience and ability, to decide what is best for the patient. That function will inevitably change. Optometrists will export data to the treating facility where the surgical plan will be formulated. The preoperative diagnostics will be integrated into the lasers used for laser refractive surgery or lasers used for cataract/refractive lens exchange and microscopes, and employed, for instance, to assist aligning toric lens orientation. Intraoperative diagnostics will confirm lens power and refractive outcome before completion of the surgical case.
One such system is the ORA system (Wavetec) which, using aberrometry, measures intraoperative refraction once a lens is removed5 and also when the lens is implanted. Toric alignment and optimisation can also be accomplished. The system has application in confirming appropriate lens power in those who have had previous laser eye surgery where lens calculation using conventional biometric methods can be quite challenging.
The devices are moving towards providing a constant live feed of refractive data and one such device that has already achieved this is the Holos intraoperative aberrometer (Clarity Medical Systems, USA).
Femtosecond laser refractive lens exchange
The ‘new new thing’ in the world of refractive lens exchange surgery is the introduction of the femtosecond laser. Already established as the gold standard for creation of flaps in Lasik, the femtosecond laser has now been adapted for intraocular use through the integration of intraoperative ocular coherence tomography (OCT) (Figure 1).
[CaptionComponent="383"]The use of OCT diagnostics has been vital in mapping out anterior segment dimensions of the eye to ensure accurate laser application to the anterior capsule for capsulotomy and lens fragmentation. The technology is expensive, but the rationale for use is the overall benefit to patients.
Keeping variables constant with a perfect round capsulotomy reduces outcome variability. This has been demonstrated with a reduction in tilt and decentration of intraocular lenses.6,7 Safety has also been demonstrated to be better with markedly reduced ultrasound time during the phacoemulsification portion of the procedure8,9 and less macular thickening postoperatively.10,11
As with many new technologies, ‘nay-sayers’ report no perceived advantage, increased cost, slower surgery and impact on trainees. These are all myths and similar arguments were used when phacoemulsification was becoming popularised – look where we are today.
Presently there are four commercial systems on the market, Victus (Bausch+ Lomb – Technolas), Catalys (Abbott Medical Optics – Optimedica), Lensx (Alcon) and LensAR (LenAR). Each device has its strengths. However, the only device that in addition to cataract surgery provides the ability to perform corneal flaps for Lasik and therapeutics such as channels for intracorneal rings and corneal transplant is the Victus femtosecond laser (Figure 2).
[CaptionComponent="384"]Intraocular lenses (IOLs)
The growth of refractive lens exchange (RLE) has been fuelled by the availability of premium or high performance lenses. The growth rate has been phenomenal in the last few years and is set to increase exponentially towards 2020 and beyond.
The successful use of current multifocals is an art-form and requires considerable attention to detail preoperatively, especially with regard to corneal optics. A good ‘marriage’ between corneal and intraocular optics is vital. Trifocal lenses, specifically the Finevision (Physiol, Belgium), introduced to the UK by the author in January 2011, have provided patients with outstanding outcomes and complete freedom from spectacles in the author’s own series of over 1,000 eyes (Figure 3).
[CaptionComponent="385"]A similar lens is available from Zeiss-Meditec (Jena, Germany) and both companies have recently introduced a toric version. Preliminary data following implantation of the toric trifocal lenses is outstanding.
As a diffractive optic lens, an adaptation period is required for some patients who may experience some difficulty with night driving. In time, all patients do adapt as long as they have corneas that are normal without dry eye problems and where there is no significant residual cylinder (less than 0.75D).12
Other diffractive lenses are essentially bifocal and sometimes used in combination with less power for near in one eye to provide some intermediate vision. Zonal refractive lenses such as the MPlus (Oculentis) have become popular but can, in the author’s experience, cause considerable and unwanted aberrations, specifically coma. Again this can become better tolerated with a period of adaptation. If not, a lens exchange may be the only remedial option.
Phakic intraocular lenses
These lenses are inserted into the eye without removing the crystalline lens. Full refractive correction can be obtained with retention of accommodation. The concept of reversibility and additional technology is very attractive for both doctor and patient.
Use of the Implantable Collamer Lenses (ICL), (Staar Surgical, Monrovia, USA) has grown considerably. Initially they were used for those with high levels of refractive error, thin corneas and dry eye. However, with phenomenal visual outcomes and rapid recovery, patients with lower levels of correction are being corrected. In Korea, some centres have completely replaced Lasik with the ICL and the overall numbers of treated patients worldwide has exceeded 500,000.
Many optometrists may ask why not perform RLE instead? The outcomes are very good, and the procedure is permanent with very little likelihood of ever requiring another procedure again. As outlined by Nanavaty and Daya in a review article, the risk of retinal detachment in myopes with high axial lengths and age below 55 is unacceptably high.13 Phakic lenses are a more appropriate alternative for the younger age group. In time, options for presbyopic phakic IOLs will no doubt become available and should be well suited to those under the age of 50.
Anterior chamber depth of at least 2.8mm from the endothelium to the anterior capsule of the lens, as well as good endothelial cell count, are prerequisites for this type of surgery.
Early presbyopes
This group of early presbyopes and the older echo-boomers is a bit more challenging. RLE, as mentioned above, is generally not a good option for those hyperopes under the age of 50 and myopes under the age of 55. No presbyopic phakic lenses are available yet. For the time being the cornea appears to be the main area of interest.
Supracor (Bausch+Lomb – Technolas) is a Lasik algorithm that corrects both distance and near and has been available for hyperopes for three years. A myopic version has recently become available in the UK. The treatment requires a Lasik flap and the algorithm creates a small zone centrally of increased power (Figure 4).
[CaptionComponent="386"]Unlike monovision, patients undergo bilateral treatment. Patients immediately have excellent near vision. Because they are used to looking through the centre of the cornea, many experience a slight reduction in distance vision initially which, with adaptation, improves. Hyperopes are typically more sensitive to a reduction in distance vision than myopes. Like RLE with multifocals, Supracor is an art form requiring careful patient selection and preoperative counselling.
Other options that have been in development and are becoming commercially available are corneal inlays. The Kamra inlay has been available commercially and works on a pinhole principle. The procedure can be combined with Lasik to provide patients with increased depth of focus. Meticulous attention to detail is again important, especially good centration.
Other inlays are the Flexivue (Presbia, Irvine CA), a small inlay that provides refractive correction, and Raindrop (Revision Optics, Lake Forest, CA) also a small inlay which alters corneal shape and produces a small area of high power centrally. Both of these inlays are placed in the cornea in a pocket or under a Lasik flap.
All three inlays are commercially available with only a few centres offering the option. The concept of adding in a device that can be easily removed or reversed is very attractive and, as more studies are conducted, we will understand the value each of these technologies brings to patients.
Finally, to allay any anxiety some readers may have, while refractive surgery is here to stay, in 2020 we will not have a spectacles-free and contact lens-free society. With newer technologies and diagnostics, growth of refractive surgery is inevitable, but the overall numbers of patients treated per year will remain small compared to those requiring spectacles and contact lenses.
However, to those optometrists who wish to be 21st century practitioners, you are urged to become involved in refractive surgery and integrate yourselves in surgical teams providing this type of surgery. The future is bright and refractive surgery done well brings phenomenal satisfaction to the providing team and, most of all, to patients.
References
1 Seiler T. Clear lens extraction in the 19th Century – An early demonstration of
premature dissemination. J Refact Surg, 1999;15 70-73.
2 Schiotz LJ. Hin Fall von hochgradigem Horn-hautstastig-ma-tis-mus nach Staarextraction: Bessergung auf operativem Wege. Arch Augenheilkd, 1885;15:178.
3 Lans LJ. Experimentelle Untersuchungen uber Entstehung von Astigmatismus durch nich-perforirende Corneawunden. Graefes Arch Ophthalmol, 1898;45:117.
4 Ecclesiastes 1:9 The Holy Bible. New international Version.
5 Huelle JO, Katz T, Druchkiv V et al. First clinical results on the feasibility, quality and reproducibility of aberrometry-based intraoperative refraction during cataract surgery. Br J Ophthalmol, 2014, May 30 [epub ahead of print].
6 Szigeti A, Kranitz K, Takacs A et al. Comparison of long-term visual outcome and IOL position with a single-optic accommodating IOL After 5.5- or 6.0-mm Femtosecond laser capsulotomy. J Refract Surg, 2012;28:9 609-13.
7 Mihaltz K, Knorz MC, Alio JL et al. Internal aberrations and optical quality after femtosecond laser anterior capsulotomy in cataract surgery. J Refract Surg, 2011;27:10 711-6.
8 Daya SM, Nanavaty MA and Espinosa-Lagana MM. Translenticular hydrodissection, lens fragmentation, and influence on ultrasound power in femtosecond laser-assisted cataract surgery and refractive lens exchange. J Cataract Refract Surg, 2014;40:1 37-43.
9 Conrad-Hengerer I, Hengerer FH, Schultz T et al. Effect of femtosecond laser fragmentation of the nucleus with different softening grid sizes on effective phaco time in cataract surgery. J Cataract Refract Surg, 2012;38:11 1888-94.
10 Ecsedy M, Mihaltz K, Kovacs I et al. Effect of femtosecond laser cataract surgery on the macula. J Refract Surg, 2011;27:10 717-22.
11 Nagy ZZ, Ecsedy M, Kovacs I et al. Macular morphology assessed by optical coherence tomography image segmentation after femtosecond laser-assisted and standard cataract surgery. J Cataract Refract Surg, 2012;38:6 941-6.
12 Villegas EA, Alcón E and Artal P. Minimum amount of astigmatism that should be corrected. J Cataract Refract Surg, 2014;40:1 13-19.
13 Nanavaty MA and Daya SM. Refractive lens exchange versus phakic intraocular lenses. Curr Opin Ophthalmol, 2012;23:1 54-61.
Read more
Towards 2020: Contact lenses of the future
Infrared contact lenses: A vision of the future
? Ophthalmologist Sheraz Daya is chairman and medical director of Centre for Sight
