Overcoming the Accommodative Decline

Presbyopia correction can be considered the holy grail of modern ophthalmology, and a plethora of techniques have been developed with the aim of overcoming the inevitable decline of accommodative amplitude that affects a vast majority of the population. Today’s patients are aware that they will eventually need visual aid to cope with near-vision difficulties. A large and continually rising percentage of these patients requests surgical intervention in order to achieve spectacle independence. In our everyday clinical practice at the Institute of Vision and Optics in Crete, Greece, we run a special clinic dedicated to presbyopia correction. Our experience treating patients in this setting includes use of corneal inlays, conductive keratoplasty (CK), and multifocal and accommodating IOLs.

CORNEA OR LENS?

Presbyopia-correcting techniques address accommodative decline at the cornea, at the sclera, or at the crystalline lens by using either a static strategy, as with monovision and multifocality, or a dynamic strategy, as with pseudoaccommodation. Choosing between cornea- and lens-based treatments can be tricky. As John Marshall, PhD, FRCPath, FRCOphth (Hon) has cleverly put it, “Why punish the cornea for the crimes of the lens?”

We believe, however, that both methods of correction should be integrated into a presbyopia clinic and a wide range of parameters considered when choosing the most appropriate technique for a patient. Below are our rationale and our surgical preferences, both cornea- and lens-based.

A patient’s personality and individual needs should be analyzed thoroughly to ensure successful treatment selection, excellent postoperative outcomes, and, most important, patient satisfaction. The equation for selecting a suitable technique and achieving high patient satisfaction can be complicated, as today’s patients are motivated by spectacle independence and are aware of their surgical options. The most successful solutions are a result of extensive preoperative examination and patient counseling and education; the surgeon must fully understand the needs of the patient before attempting any kind of correction.

CLINICAL EXPERIENCE

Over the years, we have used different presbyopiacorrection techniques with varying success rates.

Corneal inlays. Our experience with corneal inlays, in particular with the Flexivue Microlens (Presbia Coöperatief UA; Figure 1), has driven us to evaluate the advantages of this fast-developing technology. These include the minimally invasive and reversible nature of the procedure and an easy learning curve for inlay implantation.

Corneal inlays are unilaterally inserted in the nondominant eye, either with a microkeratome- or femtosecond–laserassisted method.^1,2 Both techniques are equally promising. Ideal candidates for inlay implantation are emmetropic presbyopes and postrefractive surgery patients with normal everyday expectations. Because corneal inlay insertion is reversible, it is an appealing option for patients. In order for the procedure to be successful, the patient must have good corneal clarity and absence of corneal dystrophies.

Additionally, the presence of cataract is usually a contraindication. Patients should be informed in detail about the possible need for inlay exchange to one with a higher power as their accommodative amplitude further declines with time.

Conductive keratoplasty. CK was part of our presbyopia- treatment protocol a decade ago, but concerns with the probability of induced astigmatism3 and regression4 have limited the treatment range. Patients with severe dry eye or other ocular surface problems were excluded, while an ultrasound pachymetry reading of at least 550 μm was an essential precondition to ensure a successful result.

Multifocal IOLs. Another presbyopia treatment option, implantation of multifocal IOLs, can result in satisfactory vision for both distance and near without the use of spectacles. ⁵ However, poor patient selection can create serious postoperative issues, including reduced contrast sensitivity and introduction of photic phenomena such as glare, halos, and problematic night vision. Professional drivers and patients with high corneal astigmatism must be discouraged from receiving multifocal IOLs. Equally important, patients who receive multifocal IOLs must be made familiar with the process of neural adaptation and understand that it can take up to 6 months to occur. Despite the difficulties in neural adaptation, multifocal IOLs provide an excellent option for low myopes or hyperopes with low-grade cataracts.

Accommodating IOLs. Implantation of accommodating IOLs has become an essential part of our clinical practice. In particular, we like the WIOL-CF (Medicem International CR s.r.o.) because it is designed with a bioanalogic principle that replicates the material, design, and function of a young crystalline lens (Figure 2). Patients implanted with the WIOL-CF have excellent distance and intermediate vision results, and near vision is within the range of social reading. In our experience, this lens provides high patient satisfaction and spectacle independence rates.

The target patient group for accommodating IOLs coincides with that of multifocal IOLs. But compared with multifocal IOLs, accommodating IOLs provide improved intermediate vision and fewer disturbances during night driving, when the pupil diameter is large. Postoperative counseling is crucial, providing patients with the tools to achieve maximum pseudoaccommodation, resulting in high-quality, spectacle-independent near vision.

CONCLUSION

We have no way of truly knowing what the future holds for presbyopia correction. A new technology that mimics the actual function of the crystalline lens might provide a permanent solution to near vision deterioration and overcome the problems created by an empty capsular bag secondary to cataract surgery or clear lens extraction. As a leader in presbyopia correction, the Institute of Vision and Optics is constantly evolving the technologies we offer in the field of presbyopia-correcting techniques. We have some exciting options to choose from, but there is plenty of room for new innovations.

Ioannis G. Pallikaris, MD, PhD, is a Professor of Ophthalmology at the University of Crete, and Director of the Institute of Vision and Optics, in Crete, Greece. Dr. Pallikaris states that he is Chair of the Medical Advisory Board of Presbia. He may be reached at tel: +30 2810371800; fax: +30 2810394653; e-mail: pallikar@med.uoc.gr.

Dimitra M. Portaliou, MD, practices at the University of Crete, School of Health Sciences, Institute of Vision and Optics, in Crete, Greece. Dr. Portaliou states that she has no financial interest in the products or companies mentioned. She may be reached at tel: +30 2810371800; fax: +30 2810394653; e-mail: mimi24279@gmail.com.

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