Refractive Index Shaping: In Vivo Optimization of an Implanted Intraocular Lens (IOL)

Non-mechanical steering of the optical beam in spectral-domain optical coherence tomography

“…For increasing path length differences between light reflected from the two arms of the Michelson interferometer, the amplitude of the peaks of the signal diminishes, and its width broadens, since there is a loss of frequency resolution for increasing path length differences. The two effects can be related due to the finite pixel size of the detector in the spectrometer 16 , 17 , 31 , 32 . One can correct for the amplitude decay with appropriate numerical processing of experimental data, or alternatively by applying the sensitivity decay correction depicted in Fig.…”

“…In these figures, one can observe a broadening of the peaks with increasing distance. This decrease in sensitivity with imaging depth is related to the finite spectral resolution of the spectrometer, since deeper layers are encoded in fringes with higher frequency 17 . Figure 7 c is the result of subtracting the two spectra with phase difference of , and Fig.…”

“…Spectral-domain OCT schemes provides a better axial resolution than time-domain OCT schemes 15 , 16 , and is currently the standard for ophthalmic instruments. Commercial spectral-domain OCT schemes are available that operate with imaging speeds in excess of axial scans per second 12 , 17 , 18 , which require ultrafast detection and analog-digital (AD) conversion in the Gigahertz range.…”

Current State of the Art and Next Generation of Materials for a Customized IntraOcular Lens according to a Patient-Specific Eye Power

“…Recently, there have been successful attempts to locally change the refractive index of an existing IOL by using femto-second laser pulses. This technique is termed intra-tissue refractive index shaping (IRIS) [ 82 ]. The IRIS technique is a novel, non-ablative form of vision correction by which femtosecond laser pulses are tightly focused into ocular tissues to induce localized refractive index (RI) change via nonlinear absorption.…”

“…From these data, it emerged that vacuoles are not water-filled pockets (the estimated water concentration inside a microvacuole is 23%) and mainly that, in presence of a well-distributed hydrophilic component, water is prone to be spread over the whole IOL polymeric matrix, therefore avoiding trapping by phenyl-rings-rich environments. Raman features have also been followed to identify the changes induced by a photochemical process, wherein hydrophilic polar functional groups are generated by photo-induced hydrolysis of polymeric materials in areas that are exposed to a femtosecond laser, thus providing the chemical basis for a hydrophilicity-based refractive index change, facilitating creation of a refractive index shaping lens (RIS-lens) [ 82 ].…”