Evaluating the impact of the water content of hydrophobic intraocular lenses on visual quality

Magnetic resonance imaging (MRI) study of the water content and transport in rat lenses

Tear evaporation rates were measured by resistance hygrometry in a group of five subjects wearing soft contact lenses ranging in initial water content from 38 to 70%. The water content of the lenses before and after wear was measured by a "wet blot weighing" technique using a chemical balance. The placing of all types of soft lenses on the eye disrupts the tear film sufficiently to produce significant increases in evaporation. This increase in tear evaporation was not found to be related to the initial water content of the soft lens. Water lost by dehydration of the lens material made a relatively minor contribution to the increase in evaporation from the eye during lens wear.

Changes in water content of high plus hydrogel lenses worn on an extended wear basis in a geriatric aphakic population

Quality of vision after cataract surgery after Tecnis Z9000 intraocular lens implantation: Effect of contrast sensitivity and wavefront aberration improvements on the quality of daily vision

La implantación de lentes intraoculares (LIO) en la cámara posterior ha sido ampliamente aceptada no solo para corregir errores de refracción (LIO fáquicos), sino también para reemplazar el cristalino después de la facoemulsificación (LIO pseudofáquicos). Esta tesis doctoral tiene como objetivo contribuir a nuevos conocimientos sobre el efecto de la ubicación de los diseños actuales de LIO de cámara posterior sobre la calidad de la visión y la calidad de vida.

PurposeCataract surgery has evolved into a procedure that generally yields the best postoperative refractive result attainable. Patients with multifocal intraocular lenses (IOLs) present higher rates of spectacle independence, although reduced intermediate vision, dysphotopsias, and a loss of image quality might also be experienced. The aim of the study was to review the methods for assessing quality of life and vision in patients undergoing lens refractive surgery in randomized controlled trials.MethodsWe reviewed the PubMed web platform to identify relevant studies using the following keywords: quality of life, quality of vision, lens surgery, lens exchange, refractive lens exchange, cataract, cataract surgery, intraocular lens, IOL, multifocal, and monovision.ResultsAn increasing number of studies have focused on patient-reported outcomes (PROs). Only a few of the available visual function questionnaires can be regarded as useful in lens refractive surgery with multifocal IOL implantation. Many self-developed questionnaires have emerged that have not been adequately validated or found to feature properly evaluated repeatability, hampering the possibility of comparing outcomes.ConclusionsThis review describes the existing PROs instruments and informs the choice of an appropriate measure in lens refractive surgery. Rasch-developed tools should be utilized for measuring quality of life and vision in patients undergoing lens refractive surgery and there is a number of highly robust tools available.

PurposeTo evaluate the clinical and visual outcomes, quality of near vision and the influence of photic phenomena in patients bilaterally implanted with a new Precizon Presbyopic multifocal intraocular lens (IOL).MethodsIn this prospective consecutive case series, 20 eyes of 10 patients were included (mean age 63.80 ± 12.55 years). Uncorrected and corrected visual acuity (far, intermediate and near), subjective refraction, binocular defocus curve, contrast sensitivity (CSV-1000) and quality of vision and satisfaction questionnaires were measured. The follow-up was 12 months after surgery.ResultsAt 12 months after surgery, uncorrected distance visual acuity (UDVA) improved with surgery (p = 0.001) with a value of 0.08 ± 0.08 logMAR. Uncorrected near visual acuity (UNVA) was 0.22 ± 0.12 logMAR and distance corrected near visual acuity (DCNVA) was 0.16 ± 0.13 logMAR. Intermediate distance visual acuity (UIVA) was 0.22 ± 0.10 logMAR. Contrast sensitivity outcomes were similar to normal population in photopic conditions and slightly reduced in mesopic conditions of lighting. Defocus curve showed that this multifocal IOL was able to provide a visual acuity (VA) equal or better to 0.16 logMAR between defocus levels of + 1.00 to − 2.50 D. Good patient satisfaction was obtained in quality of vision and satisfaction questionnaires outcomes.ConclusionsThe Precizon Presbyopic NVA IOL (OPHTEC BV) provides good visual outcomes. This multifocal IOL provides a high percentage of spectacle independence due to good VA at far, intermediate and near distances and satisfactory contrast sensitivity. High patient satisfaction was observed in quality of vision and satisfaction questionnaires with a low percentage of patients manifesting photic phenomena.

To compare surface alterations between preloaded and manually loaded intraocular lens. Scanning electron microscope was utilized to evaluate surface alteration and deposits in four different types of intraocular lenses: preloaded hydrophobic acrylic, preloaded hydrophilic acrylic, manually loaded hydrophobic acrylic, and manually loaded hydrophilic acrylic. Six lenses with different powers (+6 D, +22 D, and +29 D) were used from each category, to represent different thickness categories of the intraocular lenses. In total, 30 intraocular lenses have been evaluated in this study: 4 from the control group (2 hydrophobic and 2 hydrophilic lenses) and 12 from the preloaded intraocular lens and manually loaded groups (6 hydrophilic and 6 hydrophobic lenses with different powers). Surface deposits were found in eight hydrophobic intraocular lenses compared to a single intraocular lens with scattered deposits on the optical surface of a hydrophilic intraocular lens. In manually loaded intraocular lens group, five hydrophobic and one hydrophilic intraocular lenses showed identifiable marks on the optical surface. In the preloaded intraocular lens group, three hydrophobic intraocular lenses showed identifiable marks on the optical surface and three hydrophobic intraocular lenses showed surface wrinkling. All hydrophilic intraocular lenses revealed no identifiable marks. Surface alterations and deposits are a common finding in both preloaded and manually loaded intraocular lenses. Water content of acrylic intraocular lenses is an important factor predisposing to these changes, and hydrophobic intraocular lenses are more vulnerable than hydrophilic lenses. The impact on the final visual outcome needs further studies.

Optical and Visual Quality of the Visian Implantable Collamer Lens Using an Adaptive-Optics Visual Simulator

The ocular lens is an important determinant of overall vision quality whose refractive and transparent properties change throughout life. The lens operates an internal microcirculation system that generates circulating fluxes of ions, water and nutrients that maintain the transparency and refractive properties of the lens. This flow of water generates a substantial hydrostatic pressure gradient which is regulated by a dual feedback system that uses the mechanosensitive channels TRPV1 and TRPV4 to sense decreases and increases, respectively, in the pressure gradient. This regulation of water flow (pressure) and hence overall lens water content, sets the two key parameters, lens geometry and the gradient of refractive index, which determine the refractive properties of the lens. Here we focus on the roles played by the aquaporin family of water channels in mediating lens water fluxes, with a specific focus on AQP5 as a regulated water channel in the lens. We show that in addition to regulating the activity of ion transporters, which generate local osmotic gradients that drive lens water flow, the TRPV1/4-mediated dual feedback system also modulates the membrane trafficking of AQP5 in the anterior influx pathway and equatorial efflux zone of the lens. Since both lens pressure and AQP5-mediated water permeability ( ) can be altered by changes in the tension applied to the lens surface via modulating ciliary muscle contraction we propose extrinsic modulation of lens water flow as a potential mechanism to alter the refractive properties of the lens to ensure light remains focused on the retina throughout life.

Regulation of lens water content: Effects on the physiological optics of the lens

Pupil Size and LASIK

Clinical relevance It is important to distinguish between visual acuity, optical quality and quality of vision when outcomes obtained with intraocular lenses are evaluated. These parameters, that includeobjective and subjective tests, should be assessed to obtain results that are not biased. Background To assess the difference in visual and optical quality between two monofocal intraocular lens models. Methods : This was a prospective, parallel and randomised clinical study conducted at Miranza IOA, a private clinic in Madrid, Spain. Sixty patients were implanted bilaterally, 30 per group, with two aspheric IOLs with induced spherical aberration of −0.27 μm for Group A and −0.20 μm for Group B. Visual outcomes obtained at 1 and 3 months after surgery included both uncorrected (UCVA) and corrected monocular distance visual acuity (DCVA), objective scattering index (OSI), modulation transfer function (MTF) cut-off, Strehl Ratio (SR), contrast sensitivity defocus curve (CSDC), intraocular lens spherical aberration (SA), and longitudinal chromatic aberration of the eye. Activity limitations in daily life were assessed using CatQuest-9SF questionnaire. Results There were statistically significant differences for DCVA (0.04 LogMAR; p = .008) and SR (0.03; p = .003) between groups. Outcomes related to CSDC showed statistically significant differences for vergences between −0.50 D and +1.00 D (3 mm pupil) and for vergences of 0.00 D and +0.50 D (4.5 mm pupil) between groups. Overall, Group A showed better results regarding visual and optical quality, including a lower longitudinal chromatic aberration result in comparison to Group B. Patient satisfaction evaluated with CatQuest-9SF showed that Group A achieved better outcomes, although the differences were statistically significant only for the ‘Reading text on television’ item (p = 0.027). Conclusions Both intraocular lens models showed excellent quantity of vision, optical and visual quality as well as high patient satisfaction. Despite this, the the Group A model provided slightly better outcomes than the Group B model.

To compare visual outcomes, contrast sensitivity, optical quality, spectacle independence, and visual disturbances in patients implanted with 2 models of monofocal intraocular lenses (IOLs). Eye Clinic, Department of NEUROFARBA, University of Florence, Italy. Prospective case series METHODS:: Patients without ocular comorbidities and corneal astigmatism less than 0.75 diopters (D) had cataract surgery with bilateral implantation of either of 2 monofocal IOLs, the Tecnis ZCB00 or the Tecnis Eyhance ICB00 (Johnson & Johnson Vision Care, Inc.). Six months postoperatively, monocular and binocular uncorrected and corrected (at 4 m) distance visual acuities, as well as uncorrected (UIVA), distance corrected, and corrected intermediate (at 66 cm) and near (at 40 cm) visual acuities were measured. Photopic contrast sensitivity, binocular defocus curve, objective scatter index (OSI), Strehl ratio, modulation transfer function (MTF) cutoff, halo and glare perception, and spectacle independence were also evaluated. A total of 80 eyes of 40 patients were evaluated in this study. Although monocular and binocular uncorrected and corrected distance and near visual acuities were similar between groups, monocular and binocular UIVA were significantly higher in the Eyhance group. There were no statistically significant differences between the 2 groups in terms of photopic contrast sensitivity, OSI, MTF cutoff, Strehl ratio, and glare and halo perception. The ICB00 IOL provided better spectacle independence than the ZCB00 IOL for intermediate distance. In patients without ocular comorbidities, the Eyhance ICB00 IOL provided better UIVA and higher intermediate spectacle independence without impairment of far vision and visual quality, compared with the ZCB00 IOL.

Hardening of a cataractous lens is associated with the clinical appearance of brunescence and advancing age. Alterations in the nature and concentration of proteins, lens fibre compaction and other biochemical changes may all be contributing factors towards increased hardness. As the nucleus confers most of the rigidity to the lens and water content decreases towards the centre of the nucleus, the hardness might be thought to be related to total water content. To study the relationship between water content, hardness and the clinical appearance of cataract, 135 lenses were obtained from eyes undergoing extracapsular cataract surgery. The cataracts were assessed and classified pre-operatively. Lens hardness was determined by a specially designed guillotine and water content was measured by weighing the lens before and after desiccation. A regression analysis was carried out to look at the variation of lens water content with hardness, degree of nuclear sclerosis, extent of cortical and posterior subcapsular cataract, vacuolation and age. Multivariate analysis of data demonstrated a relationship between lens hardness and lens water content, degree of nuclear sclerosis and age (R2 = 0.59). An association could not be detected between lens water content and age, degree of nuclear sclerosis, extent of cortical and posterior subcapsular cataract and vacuoles. This study suggests that hardening of the lens is reflected by a respective decrease in water content. Increased hardness is associated with coloration and advancing age.