MEASURING VISION

As the diagnostic technology to measure vision evolves, a careful audit of the utility of each type of examination can help in determining which ones are still clinically useful and which have become outmoded, said Silvia Brogelli MD, Centro Oculistico Barbantini, Lucca, Tuscany, Italy. “Clinicians do not always know when it is time to change their way of operating in the diagnostic and in the surgical domains. Everything may seem to be all right in their everyday practice but internal audit can determine whether that is actually true,†she told the 16th ESCRS Winter Meeting. She and Francesco Fortunato, orthoptist, performed a review of the medical records of 3,500 patients in whom she, Marco Fantozzi and the other surgeons of their team had carried out IntraLASIK procedures since the beginning of 2009 to the end of 2011. IntraLASIK had two phases: 1) creation of a flap by Femtosecond Laser iFS 150 kHz IntraLase; 2) Photoablation by Excimer Laser Schwind Amaris. The results of the review showed a definite change in the technology used in the decision-making process. What had increased most was the use of OCT instruments for anterior segment imaging and, conversely, what had decreased most was the use of non-OCT corneal diagnostic imaging technology such as ultrasound, she said.

“We found that the continuous upgrading of hardware and software of the computerassisted instruments devoted to refractive surgery was accompanied by some changing in diagnostic procedures, although accuracy and reproducibility were always of a high level,†she explained.

Relationship with patient

Dr Brogelli noted that it is during diagnostic procedures that the refractive surgeon establishes the relationship with the patients. It is the findings of the diagnostic procedures that determine what the surgeon should tell the patient to expect. It is therefore essential that the diagnosis be carried out in the most accurate and efficient manner possible using the most up-to-date equipment, which itself must be measured against the diagnostic instrumentation that has proved tried and true in the past, she said. “No test is immortal. But no revolutionary innovation may be introduced without the help of a pre-existing clinical experience,†Dr Brogelli said. She added that the primary diagnostic procedure of refractive surgery candidates is, in effect, a visual optics laboratory applied to a specific clinical case. Visual optics is a clinical discipline that studies refraction in the context of optics ocular physiology and visual psychophysics. However, the evolving nature of visual diagnostic technology means that standardisation of diagnostic techniques has become very difficult.

Upgrading instruments

Optical instruments used to change very slowly, taking multiple generations, even centuries to be replaced, she noted. However, the continuous upgrading of hardware and software of modern computer-assisted instruments devoted to refractive surgery is accompanied by frequent changes in preliminary diagnostic protocols, better accuracy of results of measures is counterbalanced by variations in the sequence of examinations performed at different clinical centres in the same period of time and also by the same centre in different years, she said “New instruments are continually presented by some very well known companies but the ultimate choice about the surgical procedure and the instruments used must be that of the single surgical team, who must decide what is successful and what is not in their own hands,†she added.