Eyeworld

EW INTERNATIONAL 108 October 2017 by Eduardo Viteri, MD anterior chamber can be difficult to evaluate precisely. Furthermore, it is important to take into consider- ation that both the estimation of the position of the intraocular lens and the tilt angle are not perfectly pre- dictable. In addition, there are new calculation methods that consider more information and process it in many different ways. In all of these aspects, technol- ogy has achieved proceedings that must be weighed in order to deter- mine the "technology adapted" that can be offered to patients with an adequate cost-benefit analysis. The introduction of optical biometry (partial coherence interfer- ometer), the current gold standard, is a clear example that improve- ments in technology do not always represent an equivalent improve- ment in the results. Even though the measurement of the axial length During this time, we saw that the average refractive result was very close to emmetropia, but the refractive visual error presented an extensive dispersion that was grad- ually reduced from a few diopters to tenths of diopters. Our current challenge is to achieve a perfect intraocular lens power prediction for every single eye that goes through surgery—in other words, prevent refractive surprises, as we colloquial- ly define the rare cases. The intraocular lens power cal- culation requires the use of math- ematical algorithms to determine the axial length, the corneal power, and the effective intraocular lens position. Among these three factors, the first presents less variability. On the other hand, the cornea is a com- plex optical element whose anterior chamber could have anomalies in its curvature, and as a result, the try was not only expensive but also difficult to access. Those were the times when extracapsular cataract extraction was starting to prevail; when we were learning that there were contradictions to the intraoc- ular lens implant and it was consid- ered that every resident should have the ability to do cryoextraction; and when the peak of the first post-sur- gery ritual, directly at the patient's bedside, consisted of giving the patient a 12 D provisional pair of glasses. Refractive surgery was still in its early stages with its two main techniques: radial keratotomy and keratomileusis. Moreover, its appear- ance had broken the paradigm that glasses were indispensable, increased patients' expectations, and provided ophthalmologists with new con- cepts, techniques, equipment, and procedures. ALACCSA shares a recent article on IOL calculations from one of its contributors T oday, those who undergo cataract surgery are con- vinced that the refractive results are perfect in basical- ly every case. Moreover, in theory, with today's available technology, attention to details, fundamental knowledge, and a bit of good sense, the final result should always be as expected. But that hasn't always been the case. In fact, less than 4 decades ago, discussion of alternative ideas like implanting a 22 D lens in every patient or intraocular lens power calculation based on a "clinical prediction," 1 refraction or the lens optical power used before were on the table because ultrasound biome- Modern technology for intraocular lens calculations Toric intraocular lens PanOptix multifocal intraocular lens Source: Eduardo Viteri, MD

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