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Although a person can essentially live spectacle free with one of these solutions, all presbyopic procedures are a compromise, and spectacles may be required for critical vision. This is perfect for most lifestyles and occupations; however, an individual must be fully informed and understand the limitations before undergoing their procedure.
Multifocal refractive lens exchange (RLE) is becoming a very popular procedure, particularly for people over the age of 40 who are unsuitable for laser vision correction. The natural lens of the eye is replaced with an artificial lens of the exact prescription that a person requires. It boasts the benefits of not requiring cataract extraction in the future and the resulting stability of vision, which potentially could last for the entirety of a person’s life.
Intraocular lenses (IOLs) have developed extensively over many years. Indeed, their inception was borne of aphakia resulting from cataract extraction. Multifocal lenses, refractive and diffractive, were a subsequent major advance in the technology. Both categories are effective, but each have their drawbacks. For example, refractive lenses were pupil size dependent, but didn’t tend to give glare, while refractive lenses had a higher incidence of glare but were pupil size independent. In addition to this, neither offered effective intermediate vision, which is imperative to many routine daily tasks such as seeing food on a plate, gardening, and the ever increasing use of handheld devices such as smart phones and tablets. It is not until intermediate vision is compromised that a person realises its significance.
Zeiss has developed the AT LISA tri 829 MP lens, which is a trifocal lens that aims to address this issue. It blends the rings as to give a refractive/diffractive design, best of both worlds, but more importantly it offers intermediate vision.
Below is a case study from a patient treated with this lens.
Case study
This 65-year-old female hyperopic patient was treated in May 2013.
Initial refraction was:
R +4.50 / -0.75 x 92 (6\6)
L +4.25 / -0.75 x 107 (6\6)
Add +2.50 N5
Ideally, she wanted to get rid of spectacles completely through surgery. She previously had a combination of spectacles and contact lenses, neither of which gave her the independence that she desired. In the consultation, all of her options were discussed, including IntraLase Lasik for distance vision only, and the options of monofocal, multifocal and trifocal intraocular lenses.
She didn’t want distance vision only as this would require reading and intermediate spectacles. This was especially important to her as she owns and rides horses, and needs to groom and care for them, which would make readers impractical. She had tried monovision in the past, and felt that her vision was too compromised with this, effectively ruling out monofocal monovision IOLs.
In addition to visual requirements, it is always important to consider a person’s age when looking at refractive surgery. The older a person gets the more at risk they are of developing cataracts, possibly in the near future for some of these patients, thus making IOL surgery more appropriate than laser vision correction. Additionally she was not suitable for either Lasik monovision or Presbymax (Lasik that remoulds the corneal surface at several focal points for all distances), because her K-readings post-surgery would have been too steep for monovision and the scotopic pupil size for Presbymax was too large.
The process of the procedure, risks and benefits, and the realistic outcomes that she should expect, were discussed. When a person has a multifocal IOL it is quite common to lose a line on the test chart binocularly, and to require ready-readers in poor lighting situations, especially with small print. Patients must always fully understand the risks as well as the benefits of a procedure.
Due to the fact that she preferably wanted intermediate, in addition to the distance and reading, the treating surgeon agreed with the patient the best option for her would be to have the Zeiss AT LISA trifocal lens.
As with any refractive lens exchange procedure, the eyes were treated separately, in this case one week apart, and the non-dominant eye first. The consultant ophthalmologist that performed the operations inserted a Zeiss trifocal +24.5D lens in the right eye and a+25D lens in the left eye, both surgeries were uncomplicated.
Results
Table 1 shows the aftercares and visions post-operation. Optimax also documents a patient’s satisfaction at every appointment and these were ‘excellent’ over the subsequent three-month period.
Discussion
As can be seen, the results are very positive. She is extremely happy with the results, and is amazed how ‘her new eyes’ have helped her in her day to day life. It has helped her care for her horses, by allowing her to see what she is doing while grooming them, and also given her fantastic all round vision with the independence from spectacles that she has always desired. She is very family orientated, and an active grandmother; she feels that the surgery has enabled her to feel more confident when taking the grandchildren on outings, especially swimming.
In addition to this, she has had no night-time glare issues, no loss of contrast, and no other postoperative complications that can be associated with multifocal intraocular lenses.
Developing lens technology
The lens has 1.66D intermediate addition, as well as a 3.33D near addition, neither of which compromise the distance vision and gives the patients an excellent chance of leading a spectacle free life. Our experience with this lens has been positive.
The lens is a high performance aspheric multifocal IOL. It is named LISA, which is an acronym for the four principles of IOLSs:
? Light distributed asymmetrically
? Independency from pupil size
? SMP technology for ideal optical imaging quality with reduced light scattering
? Aberration correcting optimised aspheric optic for better contrast sensitivity, depth of field and sharper vision.
As well as gaining the intermediate vision, this lens provides fewer visual disturbances due to the fact it has fewer rings on the optical surface and thus improves a patient’s night vision. Night glare is a well documented complication of some multifocal intraocular lenses, which can be permanent. The Zeiss LISA tri 839 MP lens offers asymmetrical light distribution of 50 per cent, 20 per cent, 30 per cent for far, intermediate and near respectively. These areas are not only defined but also blended. This is especially significant for patients in the 40-60 age group who usually have active pupil responses at all distances. Therefore the visual outcomes can be more satisfying and predictable (Figures 2 and 3).
Finally
The patient in this case expressed her gratitude for the benefit to her real-world vision and functioning and for delivering the benefits she desired during the initial stages of her consultation. It is perhaps delivering such criteria set out by the patient themselves that should be the benchmark for any measurement of success. Too often in refractive surgery, success is measured by a certain proportion of patients being in a certain box of visual measurement and, ironically, so often even this omits critical metrics such as intermediate vision.
The reality of a patient’s view of success is more complex and must tie back to the reasons they sought treatment in the first place. The patient in this case demonstrated that careful and methodical understanding of her specific situation leads to an equally specific clinical solution. It is a pleasure for clinicians and patients alike to experience the degree of satisfaction expressed when the end result achieves this same degree of specificity. Technology, application and clinician-patient engagement is a most powerful driver of successful outcomes. ?
? Natalia Parilli Hall is a laser optometrist at Optimax, Leeds