Optical and clinical simulated performance of a new refractive extended depth of focus intraocular lens.

OBJECTIVES: The purpose of this study is to evaluate the optical and expected clinical performance of a new refractive Extended Depth of Focus (EDF) intraocular lens (IOL) designed to maintain a monofocal-like dysphotopsia profile. METHODS: Simulated visual acuity (sVA) with varying defocus was calculated using the area under the Modulation Transfer Function measured in an average eye model and from computer simulations in eye models with corneal higher-order aberrations. Tolerance to defocus was evaluated using computer simulations of the uncorrected distance sVA under defocus. To evaluate the dysphotopsia profile, halo pictures obtained using an IOL-telescope, as well as simulated images in a realistic eye model under defocus were assessed. The results of the refractive EDF were compared to those of a diffractive EDF of the same platform. RESULTS: The refractive EDF IOL provides similar range of vision to the diffractive EDF IOL with the same distance, and similar intermediate and near sVA. The refractive EDF IOL provides the same tolerance to hyperopia as the diffractive EDF but more tolerance to myopia. Halo pictures and simulations showed that the refractive EDF provides comparable dysphotopsia profile to the monofocal IOL and better than the diffractive EDF. CONCLUSIONS: The results of this preclinical study in clinically relevant conditions show that the new refractive EDF IOL is expected to provide similar range of vision to the diffractive IOL of the same platform and higher tolerance to refractive errors. The refractive EDF provides a dysphotopsia profile that is better than the diffractive EDF and comparable to that of the monofocal IOL, also in the presence of residual refractive errors.

Melanoma on congenital melanocytic nevi.

Among nevus-associated melanomas, which overall account for 20%-30% of all melanomas, those arising specifically in congenital melanocytic nevi are infrequent, but can be disproportionately frequent in childhood and adolescence. Congenital melanocytic nevi (CMNi) are common benign melanocytic tumors that are present at birth or become apparent in early childhood. They are classified based on the projected adult size. Small and medium-sized CMNi are frequent, whereas large/giant CMNi (over 20 cm in diameter) are rare, but can be associated with high morbidity due to marked aesthetic impairment and the risk of neurocutaneous syndrome or melanoma development. In this setting, melanomas can appear in early childhood and are very aggressive, while the risk of small-medium CMNi of developing melanoma is low and similar to non-congenital melanocytic nevi. Histologically, most melanomas on CMNi initiate their growth at the epidermal-dermal junction, but in large/giant CMNi they can develop entirely in the dermis, in deeper tissues, or in extracutaneous sites (especially in the central nervous system). Most CMNi harbour an NRAS mutation, but other genes are rarely involved, and gene translocations have recently been described. However, no prognostic implications have been associated with the CMN genotype. Melanomas developed on CMNi harbour additional molecular alterations to which the aggressive clinical course of these tumors has been attributed. This review covers the distinctive clinical and pathological aspects of melanomas on CMNi, and includes the epidemiology, etiopathogenesis, clinical and dermoscopic presentation, histological and molecular characteristics, as well as tumour behaviour.

Influence of decentration and tilt of Tecnis ZCB00 on visual acuity and higher order aberrations.

BACKGROUND/OBJECTIVES: To determine the influence of decentration and tilt of a pseudophakic aspheric intraocular lens (IOL) on visual acuity (VA) and higher-order aberrations (HOAs), and to analyze the agreement between pupil center/axis and iridocorneal angles center/axis when assessing IOL decentration and tilt. SUBJECTS/METHODS: A prospective interventional case series study including thirty-three patients undergoing Tecnis ZCB00 (Abbott Medical Optics) implantation. IOL decentration and tilt with respect to two reference systems (pupil and iridocorneal angles centers/axes), in cartesian (X,Y) and polar (radius/tilt, polar angle/azimuth) coordinates, were assessed with optical coherence tomography. VA and internal and ocular HOAs were evaluated. Multiple linear regression models and intraclass correlation coefficient (ICC) were computed. RESULTS: IOL decentration only showed a significant effect on internal HOAs for [Formula: see text] (R2 = 0.20, P = 0.04). IOL decentration with respect to the pupil center showed a significant effect on ocular [Formula: see text] (R2 = 0.18, P = 0.05), [Formula: see text] (R2 = 0.36, P = 0.001) and [Formula: see text] (R2 = 0.24, P = 0.02); and with respect to the center of iridocorneal angles, on ocular [Formula: see text] (R2 = 0.21, P = 0.03), [Formula: see text] (R2 = 0.32, P = 0.003), primary coma (R2 = 0.41, P < 0.001), and coma-like (R2 = 0.40, P = 0.001). Poor agreement between both reference systems was found for IOL decentration measurements (ICC ≤ 0.41), except for the polar angle coordinate (ICC = 0.83). Tilt measurements showed good agreement (ICC ≥ 0.75). CONCLUSIONS: Tecnis ZCB00 decentration and tilt values after uneventful implantation appear not to have influence on VA, and their effect on HOAs are not high enough to clinically affect quality of vision. Pupil and iridocorneal angles used as reference systems may be interchangeable for IOL tilt measurements, but not for decentration.

Predictability of sinusoidally moving stimuli does not improve the accuracy of the accommodative response.

Previous research work suggests that predictable target motion such as sinusoidal movement can be anticipated by the visual system, thereby improving the accommodative response. The validity of predictable motion for studying human dynamic accommodation is sometimes put into question. The aim of this work was to assess the effect of anticipation along with learning (and motivation, etc.) and fatigue (and boredom, loss of attention, etc.) on dynamic accommodation experiments from a practical perspective. Specifically, changes in amplitude and temporal phase lag were estimated within and between trials as 9 adult observers were instructed to focus on a stimulus that oscillated sinusoidally towards and away from the eye at specific temporal frequencies. On average, amplitude decreased whereas phase increased within trials. No evidence of anticipation or learning was observed either within or between trials. Fatigue consistently dominated anticipation and learning within the course of each trial. Even if the eye is equipped by a prediction operator as it is often assumed, fatigue confounds the results from dynamic accommodation experiments more than anticipation or learning.

Tips, quips and pearls: Ultrasound-guided distal metatarsal minimal invasive osteotomy (US-DMMO).

Metatarsalgia is a frequent cause of forefoot pain. Surgical treatment is based on the performance of osteotomies at the level of the minor radii to restore a normal distribution of pressure within the forefoot and improve the biomechanics during gait. In recent years, percutaneous surgery of the foot, and specifically distal metatarsal minimal invasive osteotomy, have proven to be a valid technique, providing satisfactory clinical results, similar to open osteotomy with less soft tissue aggression, but it requires intraoperative fluoroscopy to be performed. This article will present a modification to guide the procedure by ultrasound providing a new option that eliminates radiation and provides greater portability and accessibility.

The Effect of Retinal Illuminance on the Subjective Amplitude of Accommodation.

SIGNIFICANCE: We show that the amplitude of accommodation decreases with retinal illumination even under photopic reading conditions and a constant pupil size. This result provides a basis for clinical approaches that are not based on an optical explanation. PURPOSE: We investigated the effect of retinal illuminance on the amplitude of accommodation while the pupil of the eye remained constant. METHODS: The amplitudes of accommodation of 10 young subjects (from 20 to 38 years of age) and that of 10 presbyopic subjects (from 45 to 54 years of age) were measured subjectively through an artificial pupil of 5 mm using a Badal optometer and for four values of retinal illuminance: 222, 821, 2138, and 5074 trolands. Phenylephrine was instilled to all the subjects to ensure that their natural pupil was greater than the artificial one in all experimental runs. Linear mixed-effects model for repeated measures with age and log luminance as covariates were used to check whether changes in amplitude of accommodation with retinal illumination were statistically significant. RESULTS: In the range of illuminances tested, the amplitude of accommodation decreased on average from 6.34 to 4.35 D in the young subjects and from 1.69 to 1.04 D in the presbyopic subjects. Illuminance was associated with the amplitude of accommodation in both young and presbyopic groups, with P < .01. CONCLUSIONS: The reduction in the amplitude of accommodation with target illumination (a phenomenon named night presbyopia) under photopic light conditions is not only due to a reduction in the depth of focus as a consequence of pupil dilation; it is strongly affected by the decrease of retinal illumination.

Surgical treatment of hip fracture in centenarians: Complications and independent risk factors of death.

BACKGROUND: The increase in life expectancy has led to the appearance of a subgroup of hip fracture (HF) patients with special characteristics known as centenarians. The aim of the present study is to analyse the demographic characteristics, complications and mortality rate of this subgroup in order to identify the specific risk factors for mortality in these patients. METHODS: Retrospective analysis of 69 patients (58 women and 11 men) aged 100 years or older admitted to a tertiary hospital for HF between 1999 and 2018. RESULTS: The average age was 101.3 years (100-108, median 101). More than half (62.3%) of all patients presented with extracapsular fractures. The most common complications observed were delirium (52.3%) and urinary retention (27.7%). Haematoma (9.2%) was the most common surgical complication. Only 3 patients (7.3%) changed their place of residence after admission. In-hospital, 30-day and 1-year mortality rates were 13.8%, 21.5% and 54.2%, respectively. A high Charlson Comorbidity Index and baseline Functional Ambulation Classification (FAC) <3 were associated with a higher in-hospital mortality rate (OR = 1.95 95% CI [1.03-3.69] and OR = 5.7 95% CI [1.2-26.8]), respectively. The presence of more than 3 comorbidities and baseline FAC <3 were associated with a higher risk of 30-day mortality (OR = 6, 95% CI [1.4-24.7] and OR = 4, 95% CI [1.13-14.2]), respectively. Dementia has been associated with a higher risk of 30-day and 1-year mortality (OR = 4.6, 95% CI [1.2-16.7]) and OR = 5.11, 95% CI [1.6-21]) respectively. CONCLUSION: FAC score, number of comorbidities, dementia and the Charlson Comorbidity Index have been shown to be risk factors of mortality in centenarians with HF.

Aberrations and accommodation.

Modern methods of measuring the refractive state of the eye include wavefront sensors which make it possible to monitor both static and dynamic changes of the ocular wavefront while the eye observes a target positioned at different distances away from the eye. In addition to monitoring the ocular aberrations, wavefront refraction methods allow measurement of the accommodative response while viewing with the eye's habitual chromatic and monochromatic aberrations present, with these aberrations removed, and with specific aberrations added or removed. A large number of experiments describing the effects of accommodation on aberrations and vice versa are reviewed, pointing out the implications for fundamental questions related to the mechanism of accommodation.

The MarrowMiner: A Novel Minimally Invasive and Effective Device for the Harvest of Bone Marrow.

Bone marrow (BM) is a rich source of hematopoietic stem cells (HSCs), mesenchymal stem cells (MSCs), and other important stem/progenitor cells. It is the traditional source of cells used in hematopoietic cell transplantation, which is a proven curative treatment for many blood and immune diseases. BM-derived cells have also been shown to have other diverse clinical uses and are increasingly being used in orthopedic medicine, regenerative medicine, and gene therapy applications. Traditional methods for harvesting BM are crude, tedious, time-consuming, and expensive, requiring multiple bone punctures under general anesthesia with serial small-volume aspirates often diluted with peripheral blood. The MarrowMiner (MM) is a novel device designed for rapid and minimally invasive BM harvest. Here we show the safety and efficacy of the MM in both preclinical and clinical settings. In a large-animal porcine model, the MM enabled effective BM collection with similar total nucleated cell collection and increased colony formation compared with standard methods. The MM was subsequently evaluated in a clinical study showing effective and complication-free anterior and posterior BM collection of 20 patients under only local anesthesia or light sedation. Increased total nucleated and mononucleated cell collection was achieved with the MM compared with standard methods in the same patients. Importantly, stem cell content was high with trends toward increased HSC, MSC, and endothelial progenitor cells with similar T cell content. Given the MM is a novel device approved by the US Food and Drug Administration, enabling safe, effective, and minimally invasive harvest of BM, we anticipate rapid adoption for various applications.

Local and Widespread Pressure Pain Hyperalgesia Is Not Side Specific in Females with Unilateral Neck Pain that Can Be Reproduced during Passive Neck Rotation.

Current evidence for widespread hyperalgesia in non-specific neck pain (NSNP) is unclear. It is currently recommended to group NSNP patients according to pain-provoking movements. The aim of this study was to investigate local and widespread pain sensitivity in females with unilateral NSNP that is reproducible during passive neck rotation compared with matched controls, and to compare the side specific effect of pain location on pressure pain sensitivity among females with unilateral NSNP. Thirty-six females with unilateral NSNP evoked during passive ipsilateral (n = 20) or contralateral (n = 16) rotation toward the painful side were compared with 20 controls. Participants reported their pain intensity at rest and during passive neck rotation and completed the Neck Disability Index. Pressure pain thresholds (PPTs) were assessed bilaterally over the anterior scalene; the sternocleidomastoid; the levator scapulae; lateral to the spinous process of C6; the median, ulnar, and radial nerves; and the tibialis anterior. The ANOVA revealed lower PPTs in females with unilateral NSNP compared with the controls (all at p < 0.001), but no differences were found between the sides, nor was there any Group × side interaction. Among females with NSNP, those with higher pain intensity during ipsilateral rotation toward the painful side showed lower PPTs over the anterior scalene, median nerve, ulnar nerve, and tibialis anterior (all, p < 0.05) than females with higher pain intensity during contralateral rotation toward the painful side. These findings demonstrated bilateral local and widespread pressure pain hyperalgesia in females with unilateral NSNP that was reproducible during passive neck rotation compared with controls. There was no side specific effect of pain location on PPTs among females with unilateral NSNP.

Effect of phenylephrine on static and dynamic accommodation / Efecto de la fenilefrina sobre la acomodación estática y dinámica

Purpose: We tested the hypothesis that changes in accommodation after instillation of Phenylephrine Hydrochloride (PHCl) observed in some studies could be caused by changes in optics. Methods: We performed two experiments to test the effects of PHCl on static and on dynamic accommodation in 8 and 6 subjects, respectively. Objective wavefront measurements were recorded of the static accommodation response to a stimulus at different distances or dynamic accommodation response to a sinusoidally moving stimulus (between 1 and 3 D of accommodative demand at 0.2 Hz). The responses were characterized using two methods: one that takes into account the mydriatic optical effects on the accommodation produced by higher-order aberrations of the eye and another that takes into account only power changes paraxially due to the action of the ciliary muscle and regardless of the pupil size. Results: When mydriatic optical effects were taken into account, differences in responses before and after PHCl instillation were 0.51 ± 0.53 D, and 0.12 ± 0.15, for static and dynamic accommodation, respectively, and were statistically significant (p < 0.039). When mydriatic optical effects were not taken into account, the differences in responses before and after PHCl instillation were -0.20 ± 0.51 D, and -0.05 ± 0.14, for static and dynamic accommodation, respectively, and were not statistically significant (p > 0.313). Conclusions: The mydriatic effect of the PHCl causes optical changes in the eye that can reduce the objective and subjective measurement of accommodation

Objetivo: Probamos la hipótesis de que los cambios de la acomodación tras la instilación de Hidrocloruro de Fenilefrina (PHCl) observados en algunos estudios podrían estar originados por los cambios en la óptica. Métodos: Realizamos dos experimentos para probar los efectos de PHCl sobre la acomodación estática y dinámica en 8 y 6 sujetos, respectivamente. Se registraron las mediciones objetivas de frente de onda de la respuesta acomodativa estática a un estímulo a diferentes distancias, o la respuesta acomodativa dinámica a un estímulo con movimiento sinusoidal (entre 1 y 3 D de demanda acomodativa a 0,2Hz). Las respuestas se caracterizaron utilizando dos métodos: uno que tiene en cuenta los efectos ópticos midriáticos sobre la acomodación producida por aberraciones de alto orden, y otro que considera únicamente los cambios de potencia paraxialmente, debido a la acción del músculo ciliar, independientemente del tamaño de la pupila. Resultados: Al tenerse en cuenta los efectos ópticos midriáticos, las diferencias de las respuestas antes y después de la instilación de PHCl fueron de 0,51 ± 0,53 D, y 0,12 ± 0,15, para la acomodación estática y dinámica, respectivamente, siendo estadísticamente significativas (p < 0,039). Al no considerarse los efectos ópticos midriáticos, las diferencias en cuanto a las respuestas antes y después de la instilación de PHCl fueron de -0,2 ± 0,51 D, y -0,05 ± 0,14, para la acomodación estática y dinámica, respectivamente, no siendo estadísticamente significativas (p > 0,313). Conclusiones: El efecto midriático de PHCl origina cambios ópticos en el ojo que pueden reducir la medición objetiva y subjetiva de la acomodación

Effect of phenylephrine on static and dynamic accommodation.

PURPOSE: We tested the hypothesis that changes in accommodation after instillation of Phenylephrine Hydrochloride (PHCl) observed in some studies could be caused by changes in optics. METHODS: We performed two experiments to test the effects of PHCl on static and on dynamic accommodation in 8 and 6 subjects, respectively. Objective wavefront measurements were recorded of the static accommodation response to a stimulus at different distances or dynamic accommodation response to a sinusoidally moving stimulus (between 1 and 3 D of accommodative demand at 0.2Hz). The responses were characterized using two methods: one that takes into account the mydriatic optical effects on the accommodation produced by higher-order aberrations of the eye and another that takes into account only power changes paraxially due to the action of the ciliary muscle and regardless of the pupil size. RESULTS: When mydriatic optical effects were taken into account, differences in responses before and after PHCl instillation were 0.51±0.53 D, and 0.12±0.15, for static and dynamic accommodation, respectively, and were statistically significant (p<0.039). When mydriatic optical effects were not taken into account, the differences in responses before and after PHCl instillation were -0.20±0.51 D, and -0.05±0.14, for static and dynamic accommodation, respectively, and were not statistically significant (p>0.313). CONCLUSIONS: The mydriatic effect of the PHCl causes optical changes in the eye that can reduce the objective and subjective measurement of accommodation.

Functional outcome in pediatric hydrocephalus: results of applying the Spanish version of the Hydrocephalus Outcome Questionnaire.

OBJECTIVE The aims of the study were to assess whether the Spanish version of the Hydrocephalus Outcome Questionnaire (HOQ) could be useful for the evaluation and comparison of outcomes in the patients in the authors' region with those in patients in other institutions and to analyze predictors of functional outcome in patients with a shunt. METHODS The authors performed this cross-sectional study between March 2015 and April 2016. All the parents of a pediatric patient with hydrocephalus who attended the Hospital Regional Universitario de Málaga neurosurgery outpatient clinic were invited to enroll in the study and complete the HOQ-Spanish version. Age at diagnosis and at the time of the study, clinical data, shunt complications, and socioeconomic factors were also recorded. A descriptive analysis was performed, and independent variables related to the HOQ scores were studied. RESULTS A total of 132 patients participated in the study (100% participation rate). The mean ages were 16.74 months (range 0-142 months) at diagnosis and 10.45 years (range 5-16 years) at the time of the study. The mean overall HOQ score was 0.68 (on a scale from 0 [worse] to 1.0 [best]). Factors related to a worse quality of life were seizures, motor or visual impairment, shunt infection, need for shunt revision, need for more than 2 shunt revisions (range 0-8 revisions), symptomatic overdrainage, and older age at the time of the study. CONCLUSIONS The HOQ-Spanish version is useful in the authors' region; the dimension scores found in this study were comparable to those previously reported by referral centers. Future goals should be to prevent shunt complications, routinely get children to reach functional status, and refer patients for adjuvant therapy promptly.

Shunt overdrainage syndrome: review of the literature.

Shunt overdrainage in patients with hydrocephalus still represents a challenge for neurosurgeons, in part due to the lack of agreement or uniformity concerning the entity. Important problems exist relating to the real incidence of the entity, its definition, classification, and the pathophysiological theories behind the various treatment strategies proposed. Recent reports have suggested that the evidence about overdrainage and its consequences is not so robust as presumed. Consequently, the topic requires more detailed examination. In this review, we comment on all the main facets related with shunt overdrainage.

Amplitude, Latency, and Peak Velocity in Accommodation and Disaccommodation Dynamics.

The aim of this work was to ascertain whether there are differences in amplitude, latency, and peak velocity of accommodation and disaccommodation responses when different analysis strategies are used to compute them, such as fitting different functions to the responses or for smoothing them prior to computing the parameters. Accommodation and disaccommodation responses from four subjects to pulse changes in demand were recorded by means of aberrometry. Three different strategies were followed to analyze such responses: fitting an exponential function to the experimental data; fitting a Boltzmann sigmoid function to the data; and smoothing the data. Amplitude, latency, and peak velocity of the responses were extracted. Significant differences were found between the peak velocity in accommodation computed by fitting an exponential function and smoothing the experimental data (mean difference 2.36 D/s). Regarding disaccommodation, significant differences were found between latency and peak velocity, calculated with the two same strategies (mean difference of 0.15 s and -3.56 D/s, resp.). The strategy used to analyze accommodation and disaccommodation responses seems to affect the parameters that describe accommodation and disaccommodation dynamics. These results highlight the importance of choosing the most adequate analysis strategy in each individual to obtain the parameters that characterize accommodation and disaccommodation dynamics.

Evaluation of the iridocorneal angle with accommodation using optical coherence tomography.

The changes in the iridocorneal angle structure during accommodation are assessed by means of anterior segment optical coherence tomography. Thirteen right eyes were included in the study. The device used for the measurement was the Visante®omni system. The stimuli were set up at different vergences (0.0 D, -1.5 D, and -3.0 D). The angle opening distance 500 and 750, the trabecular iris space area 500 and 750, and the scleral spur angle parameters were assessed at the nasal and temporal regions. The results in the iridotrabecular angle comparing the three accommodative states of the eye did not yield any statistically significant difference at nasal or temporal angle sections. In light of our results and in the conditions of our study, the structures of the iridocorneal angle are not significantly changed with accommodation.

Factors related to shunt survival in paediatric hydrocephalus. Could failure be avoided? / Factores relacionados con la supervivencia del shunt en hidrocefalia pediátrica. ¿Es posible prevenir el fallo valvular?

Background: Improved shunt survival and a better understanding of factors related to failure in paediatric hydrocephalus still pose a challenge for neurosurgeons, in order to avoid morbidity and mortality, as well as the economic impact of repeated revision surgeries. For these reasons, an analysis is performed on the factors related to the first shunt failure in the long-term follow-up of a series in a single centre. Methods: A retrospective review was conducted on 166 hydrocephalic paediatric patients shunted for the first time between 2000 and 2014. An analysis was made of the statistical relationships between first shunt failure and the demographic, aetiological, surgical and clinical variables. Results: Of the 166 shunts implanted in our centre during the study period, 111 required revision over a mean follow-up period of 93 months. Factors significantly related to failure were post-haemorrhagic and post-infectious hydrocephalus, meningitis episode, posterior burr hole, differential pressure valve, standard catheter in first surgery, and symptomatic over-drainage. Multivariable analysis showed that previous meningitis and symptomatic over-drainage were risk factors for shunt failure, whereas frontal burr hole location and antibiotic-impregnated catheters were protective factors. Cox regression determined that independent factors significantly related to a worse shunt survival, were shunt infection and symptomatic over-drainage. Conclusions: Meningitis, symptomatic over-drainage, frontal burr hole, and antibiotic impregnated catheters are significant prognostic factors for shunt survival. Shunt infection and symptomatic over-drainage are independent factors significantly related to a shorter shunt survival. Prospective, randomised, controlled trials are required to validate these results

Antecedentes: Mejorar la supervivencia del shunt y conocer los factores relacionados con el fallo valvular continúa siendo un reto en neurocirugía pediátrica, con el propósito de evitar la morbimortalidad y el impacto económico de las revisiones valvulares repetidas. Por este motivo, se estudiaron los factores relacionados con el primer fallo valvular en una serie propia con un seguimiento prolongado. Métodos: Estudio retrospectivo de 166 pacientes pediátricos con hidrocefalia derivada por primera vez entre los años 2000-2014. Se analizó la asociación estadística entre el primer fallo valvular y las variables demográficas, etiológicas, quirúrgicas y clínicas. Resultados: De 166 válvulas implantadas durante el periodo de estudio, 111 requirieron revisión en un seguimiento medio de 93 meses. Los factores relacionados de forma significativa con el fallo valvular fueron las etiologías posthemorrágica y postinfecciosa; una meningitis previa; trépano posterior, válvula de presión diferencial o catéter estándar en la primera intervención, y sobredrenaje sintomático. El análisis multivariante mostró que la meningitis previa y el sobredrenaje sintomático fueron factores de riesgo para la disfunción valvular, mientras que el trépano frontal y los catéteres con impregnación antibiótica fueron factores protectores. La regresión de Cox determinó que la infección del shunt y el sobredrenaje sintomático fueron los factores relacionados de forma independiente con una menor supervivencia valvular. Conclusiones: Meningitis, sobredrenaje sintomático, trépano frontal y catéteres de impregnación antibiótica son factores pronósticos significativos en la supervivencia valvular. La infección del shunt y el sobredrenaje sintomático son factores independientes relacionados de forma significativa con una menor supervivencia valvular. Estudios controlados, prospectivos y aleatorizados son necesarios para validar estos resultados

Effect of even and odd-order aberrations on the accommodation response.

AIM: To investigate the potential effect that odd and even-order monochromatic aberrations may have on the accommodation response of the human eye. METHODS: Eight healthy subjects with astigmatism below 1 D, best corrected visual acuity 20/20 or better and normal findings in an ophthalmic examination were enrolled. An adaptive optics system was used in order to measure the accommodation response of the subjects' eyes under different conditions: with the natural aberrations being present, and with the odd and even-order aberrations being corrected. Three measurements of accommodation response were monocularly acquired at accommodation demands ranging from 0 to 4 D (0.5 D step). RESULTS: The accommodative lag was greater for the accommodative demands of 1.5, 3, 3.5 and 4 D for the condition in which the even-order aberrations were corrected, in comparison to that obtained for the natural aberrations and corrected odd-order aberrations for the same accommodation demands. No statistically significant differences were found between the accommodation responses under the three conditions. CONCLUSION: The odd and even-order aberrations are not helping the visual system to accommodate, because their partial correction do not affect the accommodation performance.