The dream of all patients when facing cataract surgery is a spectacle-free future for both near and far vision. At the same time, the eye surgeon's goal is to do his utmost for the patient to enjoy the best quality of vision attainable today. Where are we and where are we going? Our interview with Giacomo Savini
In order to have the best chance of achieving both goals, one can now use a number of diagnostic tools that have been refined in recent years of rapid progress in refractive cataract, first and foremost the biometrics.
To take stock of the 'state of the art' in this complex discipline, we asked a few questions to a super-expert, Dr Giacomo Savini, researcher at the 'G.B. Bietti' Foundation for the Study and Research in Ophthalmology in Rome.
How important is biometrics in the selection of a patient candidate for refractive cataract surgery with PC-IOL (Presbyopia Correcting IOL) implantation?
G. Savini: The implantation of multifocal lenses represents the highest expression of refractive cataract surgery. Achieving emmetropia is of fundamental importance, as even an error of 0.50 dioptres, whether hypermetropic or myopic, can limit the satisfaction of the patient, who chooses this surgery to obtain independence from glasses. I therefore believe that biometry is just as important as the performance of the surgical act, with one major difference: surgery in the hands of the experienced surgeon presents few unknowns, while the calculation of intraocular lens power is still a source of unpredictable refractive surprises. Studies published in recent years have reported that about 20-25% of eyes undergoing cataract surgery end up with a refractive error of more than 0.5 diopters. This percentage cannot be reduced with current calculation formulas and must be well known to both surgeon and patient. To all patients who are candidates for multifocal lens implants, I therefore anticipate that a 'touch-up' with the excimer laser may be necessary to correct any refractive error. If such an eventuality occurs, the patient is not surprised and undergoes LASIK or PRK more willingly.
Are there parameters that allow us to correlate preoperative anatomical parameters with postoperative visual performance?
G. Savini: Unfortunately, there are currently no well-defined parameters. The influence of the so-called K-angle, corneal asphericity, major high-order aberrations and other parameters has not yet been studied systematically and is one of the main goals I have set for research in the near future. In fact, we should be able to predict visual performance from preoperative measurements, so that we can feel more confident when proposing multifocal lens implantation to the patient. It would be helpful for everyone to be able to exclude from the use of such lenses those patients in whom preoperative measurements suggest an unsatisfactory result. A first finding is, however, emerging, at least on a theoretical level, namely the influence of anterior chamber depth. A study conducted by us at the Fondazione Bietti in Rome in collaboration with Kenneth Hoffer, and currently submitted to the Journal of Cataract and Refractive Surgeryshowed that the near reading distance is greater the deeper the anterior chamber is after surgery. In other words, the further the intraocular lens is from the cornea, the further the patient has to move away from what he or she wants to focus on near. Since, in most cases, a deep anterior chamber after surgery is typical for myopes, it follows that these patients may have more difficulty reading near with a multifocal lens. This fact had already been recognised by Hoffer and Holladay, who published a paper in 1991 showing that the addition should be increased in proportion to the depth of the anterior chamber.
What advice can we give IOL EDOF users to achieve the expected refractive target?
G. Savini: The recommendations are those valid for the calculation of all lenses: 1) measure the axial length with optical biometry or immersion biometry and not with contact lenses; 2) exclude corneal astigmatisms greater than 0.5 diopters, also considering the posterior corneal surface. For this reason it is indispensable to have a Scheimpflug camera that gives a measurement of total corneal astigmatism; 3) use the most modern formulas: Haigis, Hoffer Q, Holladay 1 and 2, SRK/T. Avoid SRK II; 4) optimise the constants for your instruments. The technique I traditionally favour is immersion biometry, combined with SimKs (obtained with the Optikon 2000 Keratron topographer). With this combination, the constants for the Mini WELL are 5.39 (Hoffer Q), 1.61 (Holladay 1) and 118.82 (SRK/T). Equally good results can be obtained with Topcon's Aladdin optical biometer, in which case the constants are 5.64 (Hoffer Q), 1.85 (Holladay 1) and 119.18 (SRK/T). The constants for the IOLMaster, calculated by Dr. Carbonara of Rome, are 5.26 (Hoffer Q), 1.48 (Holladay 1) and 118.67 (SRK/T); 5) use the Hoffer Q for short eyes (<22 mm), the average of the Hoffer Q, Holladay 1 and SRK/T for medium eyes (22-24.5 mm), the Holladay 1 for medium-long eyes (24.5 - 26 mm) and the SRK/T for long eyes.
James Savini
A researcher with an international profile, he graduated and took the first steps of his career in Bologna.
Since 2009, he has been a researcher at the G.B. Bietti Foundation - IRCCS in Rome.
In clinical practice, he focused on cataract and refractive surgery.
In terms of research, the calculation of intraocular lens power represents the field of greatest interest.
Very active in terms of scientific publications, he has more than 100 papers in peer-reviewed journals to his credit.
His studies in the field of biometrics have led him to join the IOL Power Club since 2007 (www.iolpowerclub.org), a club that brings together the world's leading biometrics experts (Hoffer, Haigis, Olsen, Shammas and Aramberri).
Read this article in English.
For more details see our review on surgical correction of presbyopia:
– Innovative IOLs: the future is already tomorrow
– The new EDOF IOLs in the correction of presbyopia
– New horizons for presbyopia surgery
– Presbyopia and economic growth
Dr. Carmelo Chines
Direttore responsabile
English 
Italian