Biomedical subjects

Rafael Navarro

Publications and source records attributed to Rafael Navarro.

17 recordsLinked to original sources

PubMed2006

Palladium complexes of a phosphorus ylide with two stabilizing groups: synthesis, structure, and DFT study of the bonding modes.

The phosphorus ylide ligand [Ph3P=C(CO2Me)C(=NPh)CO2Me] (L1) has been prepared and fully characterized by spectroscopic, crystallographic, and density functional theory (DFT) methods (B3LYP level). The reactivity of L1 toward several cationic Pd(II) and Pt(II) precursors, with two vacant coordination sites, has been studied. The reaction of [M(C/\X)(THF)2]ClO4 with L1 (1:1 molar ratio) gives [M(C/\X)(L1)]ClO4 [M = Pd, C/\X = C6H4CH2NMe2 (1), S-C6H4C(H)MeNMe2 (2), CH2-8-C9H6N (3), C6H4-2-NC5H4 (4), o-CH2C6H4P(o-tol)2 (6), eta3-C3H5 (7); M = Pt, C/\X = o-CH2C6H4P(o-tol)2 (5); M(C/\X) = Pd(C6F5)(SC4H8) (8), PdCl2 (9)]. In complexes 1-9, the ligand L1 bonds systematically to the metal center through the iminic N and the carbonyl O of the stabilizing CO2Me group, as is evident from the NMR data and from the X-ray structure of 3. Ligand L1 can also be orthopalladated by reaction with Pd(OAc)2 and LiCl, giving the dinuclear derivative [Pd(mu-Cl)(C6H4-2-PPh2=C(CO2Me)C(CO2Me)=NPh)]2 (10). The X-ray crystal structure of 10 is also reported. In none of the prepared complexes 1-10 was the C(alpha) atom found to be bonded to the metal center. DFT calculations and Bader analysis were performed on ylide L1 and complex 9 and its congeners in order to assess the preference of the six-membered N,O metallacycle over the four-membered C,N and five-membered C,O rings. The presence of two stabilizing groups at the ylidic C causes a reduction of its bonding capabilities. The increasing strength of the Pd-C, Pd-O, and Pd-N bonds along with other subtle effects are responsible for the relative stabilities of the different bonding modes.

Journal Article↗

PubMed2006

Microarray-based mutation analysis of the ABCA4 gene in Spanish patients with Stargardt disease: evidence of a prevalent mutated allele.

PURPOSE: To evaluate, in a pool of affected families, the mutation spectrum in Stargardt patients from Spain, using the ABCR400 microarray that contains described sequence variants in the gene encoding for the photoreceptor specific ATP-binding cassette transporter (ABCA4). METHODS: We analyzed 76 Spanish patients with STGD1 for a population-specific survey on the sequence variations in the ABCA4 gene, using the ABCR400 microarray. RESULTS: Potential disease-associated alleles were identified in 91 of the 152 STGD1 chromosomes studied, resulting in a detection rate of 60%. The two mutant alleles were found in 33/76 patients (43%), whereas in 25/76 cases (33%) only one allele could be identified. In the remaining 18 patients no mutations were found. In total, we identified 40 sequence variations that could be related to the disease. The vast majority of these substitutions (35/40) were missense mutations. Three frameshift mutations and two splicing variants were also found. CONCLUSIONS: We identified a major disease-associated allele, R1129L, which accounted for 24% of the mutated alleles detected, and a high frequency (12%) of complex alleles.

ATP-Binding Cassette Transporters↗

PubMed2006

Hydrogen capacity of palladium-loaded carbon materials.

Several samples of palladium-loaded single-wall carbon nanotubes and palladium-loaded MAXSORB activated carbon were prepared by means of the reaction of the raw carbon support with Pd2(dba)3.CHCl3. When carbon nanotubes were used as the support, the palladium content in the samples reached 13-31 wt % and fine particles of 5-7 nm average size were obtained. In the case of the samples with MAXSORB as the support, the palladium content was higher (30-50 wt %) and the particle size larger (32-42 nm) than in the nanotube samples. At 1 atm and room temperature, the hydrogen capacity of the palladium-loaded samples exceeds 0.1 wt % and is much higher than the capacity of the raw carbon supports (less than 0.01 wt %). The maximum hydrogen capacity at 1 atm and room temperature was found to be 0.5 wt %. A maximum hydrogen capacity of 0.7 wt % was obtained at 90 bar in a palladium-loaded MAXSORB sample, while the capacities for the raw carbon nanotubes and MAXSORB at the same pressure were 0.21 and 0.42 wt %, respectively. At low pressure, it was observed that the H/Pd atomic ratios in the palladium-loaded samples were always higher than in the bulk Pd. The spillover effect is considered as a possible cause of the high H/Pd atomic ratios. On the other hand, the effect of the pressure increase on the spillover was observed to be very low at high pressure and room temperature.

Journal Article↗

PubMed2006

On the prediction of optical aberrations by personalized eye models.

PURPOSE: The purpose of this study is to develop and analyze a method to obtain optical schematic models of individual eyes. Each model should be able to reproduce the measured monochromatic wave aberration with high fidelity. METHODS: First, we choose a generic eye model as the input guess and then apply a two-stage customization procedure. Stage 1 consists of replacing, in the initial generic model, those anatomic and optical parameters with experimental data measured on the eye under analysis. The set of experimental data was that provided by a standard clinical preoperative examination, namely lens topography, ultrasound biometry, and total wave aberration. Then, the second stage is to find the unknown lens structure that would reproduce the measured wave aberration through optical optimization. Two totally different initial eye models have been compared; one considers a simpler constant refractive index for the lens, whereas the second model has a gradient-index (GRIN) lens. RESULTS: This automatic customization method has been applied to 19 eyes with different degrees of spherical ametropia (from +0.4 D to -8 D). Two models have been obtained for each eye (constant and gradient index lens). The results were highly satisfactory, with 100% convergence, and with average RMS prediction errors approximately lambda/100. This is one order of magnitude lower than typical measurement errors. The models with a constant refractive index lens tended to overestimate surface curvatures, whereas for the GRIN model, lens surfaces were too flat. CONCLUSIONS: The proposed method is highly efficient and robust giving a high-fidelity reproduction of the wavefront in all cases attempted so far. Limitations found in reproducing the geometry of the lens seem to be associated with the use of inaccurate models of its refractive index.

Accommodation, Ocular↗

PubMed2006

Nonlinear image representation for efficient perceptual coding.

Image compression systems commonly operate by transforming the input signal into a new representation whose elements are independently quantized. The success of such a system depends on two properties of the representation. First, the coding rate is minimized only if the elements of the representation are statistically independent. Second, the perceived coding distortion is minimized only if the errors in a reconstructed image arising from quantization of the different elements of the representation are perceptually independent. We argue that linear transforms cannot achieve either of these goals and propose, instead, an adaptive nonlinear image representation in which each coefficient of a linear transform is divided by a weighted sum of coefficient amplitudes in a generalized neighborhood. We then show that the divisive operation greatly reduces both the statistical and the perceptual redundancy amongst representation elements. We develop an efficient method of inverting this transformation, and we demonstrate through simulations that the dual reduction in dependency can greatly improve the visual quality of compressed images.

Algorithms↗

PubMed2006

Optics of the average normal cornea from general and canonical representations of its surface topography.

Generally, the analysis of corneal topography involves fitting the raw data to a parametric geometric model that includes a regular basis surface, plus some sort of polynomial expansion to adjust the more irregular residual component. So far, these parametric models have been used in their canonical form, ignoring that the observation (keratometric) coordinate system is different from corneal axes of symmetry. Here we propose, instead, to use the canonical form when the topography is referenced to the intrinsic corneal system of coordinates, defined by its principal axes of symmetry. This idea is implemented using the general expression of an ellipsoid to fit the raw data given by the instrument. Then, the position and orientation of the three orthogonal semiaxes of the ellipsoid, which define the intrinsic Cartesian system of coordinates for normal corneas, can be identified by passing to the canonical form, by standard linear algebra. This model has been first validated experimentally obtaining significantly lower values for rms fitting error as compared with previous standard models: spherical, conical, and biconical. The fitting residual was then adjusted by a Zernike polynomial expansion. The topographies of 123 corneas were analyzed obtaining their radii of curvature, conic constants, Zernike coefficients, and the direction and position of the optical axis of the ellipsoid. The results were compared with those obtained using the standard models. The general ellipsoid model provides more negative values for the conic constants and lower apex radii (more prolate shapes) than the standard models applied to the same data. If the data are analyzed using standard models, the resulting mean shape of the cornea is consistent with previous studies, but when using the ellipsoid model we find new interesting features: The mean cornea is a more prolate ellipsoid (apical power 50 D), the direction of the optical axis is about 2.3 degrees nasal, and the residual term shows three Zernike coefficients significantly higher than zero (third-order trefoil and fourth- and sixth-order spherical). These three nonzero Zernike coefficients are responsible for most of the higher-order aberrations of the average cornea. Finally, we propose and implement a simple method for three-dimensional registration of corneal topographies, passing from the general to the canonical form of the ellipsoid.

Adult↗

PubMed2006

A new calibration set of phase plates for ocular aberrometers.

PURPOSE: To manufacture and test a set of phase plates for the calibration of ocular aberrometers and apply it to the calibration of an ocular laser ray tracing aberrometer. METHODS: The set of phase plates is made by a greyscale single-mask photosculpture in photoresist method. Each plate induces a given amount of a particular aberration (Zernike) mode. The set contains two subsets: 1) pure Zernike modes to test the accuracy among different orders (from 3rd to 7th, approximately 0.3 to 0.4 microm); and 2) plates having different amounts of the same mode, 3rd order coma ranging from 0.11 to 0.47 microm. After manufacturing, the plates were tested twice, as a crosscheck, measuring the aberration pattern of each plate with a Mach-Zehnder interferometer and a single-pass Hartmann-Shack wavefront sensor. The set was then applied to the calibration of an ocular double-pass laser ray tracing aberrometer. RESULTS: Close agreement was found between the three types of measurement. The maximum difference between Hartmann-Shack and laser ray tracing measurements was 0.032 microm (ie, approximately lambda/20, half of the typical measuring error in human eyes). This permitted detection of a small bias in the ocular laser ray tracing aberrometer. CONCLUSIONS: The calibration set may be a powerful tool for the assessment of accuracy and reliability in ocular aberrometry. It discovered a small bias, which is almost impossible to detect when working with human eyes or trial lenses. This type of calibration tool is especially important in clinical environments.

Calibration↗

PubMed2004

Synthesis and characterization of Pd(II) Complexes with bis-pyridinium and isoquinolinium N-ylides: moderate C-H...O=C intramolecular hydrogen bonds as source of conformational preferences.

The bis(N-ylide) Pd(II) complexes cis-[PdX2[eta2-[C(H)NCxHy]2CO]] (X=I, NCxHy=NC5H5, 2a; X=Br, NCxHy=NC5H5 and NC5H3-2,3-Me2, 2c, isoquinolinium NC9H7, 2d) have been prepared by reaction of the corresponding bis-pyridinium salts with Pd(OAc)2 (1:1 molar ratio). Compounds 2 react with AgClO4 and Tl(acac) (1:1:1 molar ratio) to give the acetylacetonato derivatives [Pd(acac-O,O'[eta2-[C(H)NCxHy]2CO]]ClO4 (3a, c, d). In compounds 2 and 3, the bis-ylide is bonded as a C,C-chelate ligand through the two ylidic Calpha atoms. The reaction is stereoselective, and only one diastereoisomer is observed (meso form, RS/SR). The origin of the observed stereoselectivity lies with the establishment of intramolecular C-H...O=C hydrogen bonds between the ortho protons of the pyridine or isoquinoline fragments and the carbonyl oxygen, as it has been shown by density functional theory (DFT) calculations (B3LYP level) and Bader analysis of the electron density on model pyridinium ylides. Despite the inherent weakness of the C-H...O=C bonds, the results show that in these N-ylides the hydrogen bonds are stronger than expected and should be classified as moderate H bonds.

Journal Article↗

PubMed2003

31P NMR spectroscopy as a powerful tool for the determination of enantiomeric excess and absolute configurations of alpha-amino acids.

An easy method for the determination of the enantiomeric excess (ee) of mixtures of alpha-amino acids, and also for the elucidation of the absolute configuration of each component of the mixture, is reported. The method is based on the formation of diastereoisomers by reaction of the enantiomerically pure acetylacetonate derivative [Pd(acac-O,O')(P(2)-dach)]ClO(4) (4) [P(2)-dach = (1R,2R)-C(6)H(10)(NHPPh(2))(2)] with d,l-mixtures of alpha-amino acids AaH (Pd:AaH = 1:1 molar ratio, refluxing MeOH). The reaction occurs with protonation of the acac ligand and N,O-coordination of the amino acidate group, giving the corresponding [Pd(Aa-N,O)(P(2)-dach)]ClO(4) complexes l-5 and d-6. The composition of these mixtures of amino acidate complexes was analyzed by integration of the corresponding peaks (four doublets, two for each diastereomer) in their (31)P((1)H) NMR spectra. A series of 14 alpha-amino acids was studied (a, alanine; b, 2-aminobutyric acid; c, valine; d, phenylalanine; e, proline; f, leucine; g, isoleucine; h, norleucine; i, serine; j, threonine; k, methionine; l, aspartic acid; m, glutamine; n, cysteine), and excellent agreement between the expected values of ee and those obtained from integration of the (31)P((1)H) NMR spectra was obtained. Moreover, the position of the signals of each isomer is diagnostic, in such a way that the outer doublets are always due to the l-derivatives 5a-l, while the inner ones are due to the d-derivatives 6a-l, allowing the assignation of absolute configurations to each isomer in the mixture.

Amino Acids↗

PubMed2003

Wide-field compensation of monochromatic eye aberrations: expected performance and design trade-offs.

The optical quality of the human eye varies across the visual field. Hence an exact compensation of the eye aberration for a given field point can give rise to a less-than-optimum compensation in neighboring field regions. We have studied some aspects of this problem and present here an approach to design wide-field (< 10 degrees) optically thin correcting elements, e.g., phase plates, deformable mirrors, and liquid-crystal displays. Their expected performance is assessed using actual eye aberration data. Particular attention is given to the design of elements providing a minimum averaged rms residual aberration and those providing a nearly uniform rms residual aberration across a given field.

Color Vision Defects↗

PubMed2003

Bayesian model of Snellen visual acuity.

A Bayesian model of Snellen visual acuity (VA) has been developed that, as far as we know, is the first one that includes the three main stages of VA: (1) optical degradations, (2) neural image representation and contrast thresholding, and (3) character recognition. The retinal image of a Snellen test chart is obtained from experimental wave-aberration data. Then a subband image decomposition with a set of visual channels tuned to different spatial frequencies and orientations is applied to the retinal image, as in standard computational models of early cortical image representation. A neural threshold is applied to the contrast responses to include the effect of the neural contrast sensitivity. The resulting image representation is the base of a Bayesian pattern-recognition method robust to the presence of optical aberrations. The model is applied to images containing sets of letter optotypes at different scales, and the number of correct answers is obtained at each scale; the final output is the decimal Snellen VA. The model has no free parameters to adjust. The main input data are the eye's optical aberrations, and standard values are used for all other parameters, including the Stiles-Crawford effect, visual channels, and neural contrast threshold, when no subject specific values are available. When aberrations are large, Snellen VA involving pattern recognition differs from grating acuity, which is based on a simpler detection (or orientation-discrimination) task and hence is basically unaffected by phase distortions introduced by the optical transfer function. A preliminary test of the model in one subject produced close agreement between actual measurements and predicted VA values. Two examples are also included: (1) application of the method to the prediction of the VAin refractive-surgery patients and (2) simulation of the VA attainable by correcting ocular aberrations.

Bayes Theorem↗

PubMed2003

Optimal coding through divisive normalization models of V1 neurons.

Current models of the primary visual cortex (V1) include a linear filtering stage followed by a gain control mechanism that explains some of the nonlinear behaviour of neurons. This nonlinear stage consists of a divisive normalization in which each linear response is squared and then divided by a weighted sum of squared linear responses in a certain neighbourhood plus a constant. Simoncelli and Schwartz (1999 Adv. Neural Inform. Process. Syst. 11 153-9) have suggested that divisive normalization reduces the statistical dependence between neuron responses when the weights are adapted to the statistics of natural images, which is consistent with the efficient coding hypothesis. Nevertheless, there are still important open issues, such as, for example, how to obtain the values for the parameters that minimize statistical dependence? Does divisive normalization give a total independence between responses? In this paper, we present the general mathematical formulation of the first of these two questions. We arrive at an expression which permits us to compute, numerically, the parameters of a quasi-optimal solution adapted to an input set of natural images. This quasi-optimal solution is based on a Gaussian model of the conditional statistics of the coefficients resulting from projecting natural images onto an orthogonal linear basis. Our results show, in general, lower values of mutual information, that is, responses are more independent than those provided by previous approximations.

Models, Neurological↗

PubMed2003

Input-output statistical independence in divisive normalization models of V1 neurons.

Simoncelli and co-workers have proposed statistically-derived nonlinear divisive normalization models of the primary visual cortex (V1) that are consistent with the hypothesis that sensory systems are adapted to the signals to which they are exposed. In this paper, we present a more rigorous mathematical formulation and analysis of these statistically-derived models in terms of mutual information as a metric for statistical independence. We prove that the ad hoc choice of divisive normalization parameters proposed by Simoncelli and co-workers does not guarantee statistical independence between the output responses, but interestingly such choice does guarantee that each output response is statistically independent of almost all the linear inputs. This holds for the two different models of natural image statistics analysed theoretically, and is consistent with empirical results obtained on a set of natural images.

Animals↗

PubMed1998

Synthesis and Structure of Pd(II) Complexes Containing the C,C-Chelating Bis-Ylide Ligand [Ph(3)P=C(H)](2)CO. X-ray Crystal Structure of {Pd(&mgr;-Cl){[C(H)PPh(3)](2)CO}}(2)(ClO(4))(2).CH(2)Cl(2).

The reaction of Pd(OAc)(2) with the bis(phosphonium) salt [Ph(3)PCH(2)COCH(2)PPh(3)]Cl(2) (1:1 molar ratio) results in the formation of the cis-dichlorobis(ylide) derivative Cl(2)Pd{[C(H)PPh(3)](2)CO}, 1, in which the bis(ylide) ligand [C(H)PPh(3)](2)CO acts as a chelating group through the two ylide carbon atoms. Complex 1 reacts with TlClO(4) (1:1 molar ratio) to give [Pd(&mgr;-Cl){[C(H)PPh(3)](2)CO}](2)(ClO(4))(2), 2, which reacts with two further equivalents of TlClO(4) in NCMe to give [Pd{[C(H)PPh(3)](2)CO}(NCMe)(2)](ClO(4))(2) 3. The reactivity of 2 and 3 has been explored. Compound 2 reacts with pyridine, 3,5-lutidine, or Ph(3)P=C(H)CN (1:2 molar ratio), resulting in the rupture of the chlorine bridging system and formation of [PdCl{[C(H)PPh(3)](2)CO}(L)](ClO(4)) (L = py (4), 3,5-lu (5), NC-C(H)=PPh(3) (6)), and with Tlacac (1:2 molar ratio) with formation of the acetylacetonate [Pd(acac){[C(H)PPh(3)](2)CO}](ClO(4)), 7. On the other hand, complex 3 reacts with the ylide Ph(3)P=C(H)CN (1:2 molar ratio) giving [Pd{[C(H)PPh(3)](2)CO}[NC-C(H)=PPh(3)](2)](ClO(4))(2), 8, which contains two N-coordinated ylides, and with NBu(4)OH (1:1) to give [Pd(&mgr;-OH){[C(H)PPh(3)](2)CO}](2)(ClO(4))(2), 9. The reaction of Pd(OAc)(2) with the ylide phosphonium salt [Ph(3)P=C(H)COCH(2)PPh(3)](ClO(4)) (1:1) gives the acetate dimer [Pd(&mgr;-OOCCH(3)){[C(H)PPh(3)](2)CO}](2)(ClO(4))(2), 10. The structures of complexes 1-10 were deduced from their spectroscopic data and from the resolution of the molecular structure of complex 2.CH(2)Cl(2).

Journal Article↗

PubMed1997

Nitrogen- vs Carbon-Coordination of the alpha-Cyano-Stabilized Phosphorus Ylide Ph(3)P=C(H)CN. X-ray Crystal Structure of {Pd(dmba)[P(OMe)(3)][N&tbd1;C-C(H)=PPh(3)]}(ClO(4)).

The reaction of the solvated complexes [Pd(C&arcraise;N)(PR'(3))(THF)](ClO(4)) [C&arcraise;N = 2-((dimethylamino)methyl)phenyl-C(1),N or dmba, 2-(1-(R)-(dimethylamino)ethyl)phenyl-C(1),N or (R)-dmphea; PR'(3) = PPh(3), P(OMe)(3)] with a stoichiometric amount of Ph(3)P=C(H)CN (CPPY) (1:1 molar ratio), in THF at low temperature, gives the cationic derivatives {Pd(C&arcraise;N)(PR'(3))[N&tbd1;C-C(H)=PPh(3)]}(ClO(4)), 4-6, in which the ylide ligand is N-coordinated to the Pd(II) center and trans to the ortho-metalated C(6)H(4) group, in an "end-on nitrile" coordination mode that is unprecedented for this ylide. The reaction of [Pd(C&arcraise;N)(NCMe)(2)](ClO(4)) (C&arcraise;N = dmba, (R)-dmphea) with Ph(3)P=C(H)CN (1:2 molar ratio) gives the bis(ylide) complexes [Pd(C&arcraise;N)(Ph(3)PCHCN)(2)](ClO(4)) (7, 8) in which one of the ylides is C-coordinated (trans to the NMe(2) group) and the other one is N-bonded (and trans to the C(6)H(4) group). Either by reaction of [Pd(C&arcraise;N)(NCMe)(2)](ClO(4)) with Ph(3)P=C(H)CN (1:1 molar ratio) or by reaction of the bis(ylide) complexes [Pd(C&arcraise;N)(Ph(3)PCHCN)(2)](ClO(4)) with [Pd(C&arcraise;N)(NCMe)(2)](ClO(4)) (1:1 molar ratio), very insoluble materials of stoichiometry [Pd(C&arcraise;N)(Ph(3)PCHCN)(ClO(4))] (9, 10) are obtained, which appear to be dinuclear derivatives with the ylide acting as a C,N-bridging group, [(C&arcraise;N)Pd(&mgr;-C,N-Ph(3)PCHCN)(2)Pd(C&arcraise;N)](ClO(4))(2). At the same time, this ylide is shown to be sufficiently nucleophilic to promote the bridge-splitting of the dinuclear [Pd(&mgr;-Cl)(C&arcraise;N)](2) complexes, giving the mononuclear derivatives [PdCl(C&arcraise;N)(Ph(3)PCHCN)] (11, 12) as a mixture of two isomers; in one of them, the ylide acts as a C-donor while in the other it acts as an N-donor. IR and NMR spectroscopies allow the unambiguous characterization of all of these products, and the X-ray crystal structure of {Pd(dmba)[P(OMe)(3)][N&tbd1;C-C(H)=PPh(3)]}(ClO(4)) (5) is reported. Complex 5 crystallizes in the monoclinic system, space group P2(1)/c, a = 12.5690(10) Å, b = 17.857(2) Å, c = 14.729(2) Å, beta = 92.560(10) degrees, Z = 4, V = 3302.5(6) Å(3), 4881 reflections with I > 2sigma(I) for the refinement of 423 parameters and 30 restraints, R1 = 0.0384, wR2 = 0.0961, and GOF = 1.044.

Journal Article↗

PubMedDate not supplied

Accuracy and reproducibility of Zywave, Tracey, and experimental aberrometers.

PURPOSE: To compare the accuracy and verify the reliability of different commercial and experimental prototypes of aberrometers using a small group of normal subjects with low myopia. METHODS: Three different devices were used to measure the wavefront aberration of five normal myopic eyes: 1) Zywave--commercial aberrometer based on a Hartmann-Shack wavefront sensor; 2) Tracey--commercial system based on the laser ray tracing principle; and 3) an experimental laboratory laser ray tracing instrument working at two different wavelengths (532 and 786 nm). A series of five measurements were taken for each subject. Pupil diameter and alignment were controlled. All wave aberration maps were reduced to a common 6.5-mm pupil diameter, and then the mean and standard deviation were computed for the series, as well as the global average and standard deviation for each subject. RESULTS: Despite several important differences among devices and sessions, the results obtained with the different devices were equivalent. The main difference found between aberrometers was due to the longitudinal chromatic aberration caused by the use of different wavelengths. The signal-to-noise ratio estimated from the raw data was moderate, 12, but could be improved by a factor of 2 by discarding those measurements with a higher deviation from the mean and averaging the remaining data, which was the approach implemented in the Zywave instrument. CONCLUSION: The aberrometers tested were reliable in normal eyes with low myopia. Aberrometry is a robust but noisy technique. Accuracy is limited by noise and other sources of variability, including the size and alignment of the pupil. These conclusions might not apply to eyes with large aberrations.

Adult↗

PubMedDate not supplied

Bilateral giant retinal tear following posterior chamber phakic intraocular lens implantation.

PURPOSE: To report a case of bilateral giant retinal tear following posterior chamber phakic intraocular lens (PIOL) implantation. METHODS: A patient with an ocular history of retinal detachment associated with giant retinal tear 4 months after a bilateral PIOL implantation was referred with a macula on retinal detachment associated with giant retinal tear in the fellow eye. The patient underwent vitrectomy with silicone oil tamponade and an encircling buckle. Five months later, a lensectomy with phakic IOL and silicone oil removal were performed. RESULTS: The retina was reattached and has remained stable during 3-year follow-up. CONCLUSIONS: Although it is unclear whether retinal detachment associated with giant retinal tear following refractive procedures occurs within the normal incidence in myopic eyes, prophylactic measures are mandatory in high-risk fellow eyes.

Adult↗