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PURPOSE: To evaluate peripheral refraction and contrast detection sensitivity in pseudophakic patients implanted with a new type of inverted meniscus intraocular lens (IOL) (Art25; Voptica SL) that was designed to provide better peripheral optics. METHODS: One month after cataract surgery, in 87 eyes implanted with the Art25 IOL, peripheral contrast detection sensitivity was measured psychophysically at 40° visual angle, both horizontally and vertically, and compared with a control group of 51 eyes implanted with standard biconvex IOLs. Thirty-one eyes with the Art25 IOL and 28 eyes from the control group were randomly selected to also measure peripheral refraction using a scanning Hartmann-Shack wavefront sensor along 80° in the horizontal meridian. RESULTS: Most patients achieved emmetropia and good visual acuity, and no significant adverse events were observed after cataract surgery with Art25 IOLs. Peripheral contrast detection sensitivity was significantly better ( P < .01) in the group with the Art25 IOL in both directions (7.78 ± 3.24 vs 5.74 ± 2.60 vertical, 10.98 ± 5.09 vs 7.47 ± 3.96 horizontal), which was in agreement with the optical quality improvement in the periphery due to a reduction of defocus (1.97 and 1.21 diopters [D] at 40° temporal and nasal sides) and astigmatism (1.17 and 0.37 D at 40° temporal and nasal sides) that was statistically significant ( P < .01) from 20° of eccentricity. CONCLUSIONS: Patients implanted with a new inverted meniscus IOL present a reduced amount of peripheral defocus and astigmatism compared to patients implanted with standard biconvex IOLs. This improvement in optical quality leads to better contrast detection sensitivity measured at 40° of eccentricity. [ J Refract Surg . 2022;38(4):229–234.]

A novel double-pass instrument and its data analysis method for the measurement of central and peripheral refraction is presented and validated in a group of healthy subjects. The instrument acquires in-vivo, non-cycloplegic, double-pass, through-focus images of the eye’s central and peripheral point-spread function (PSF) using an infrared laser source, a tunable lens and a CMOS camera. The through-focus images were analyzed to determine defocus and astigmatism at 0° and 30° visual field. These values were compared to those obtained with a lab-based Hartmann-Shack wavefront sensor. The two instruments provided data showing good correlation at both eccentricities, particularly in the estimation of defocus.

Current intraocular lenses (IOLs) are designed to substitute the cataractous crystalline lens, optimizing focus at the fovea. However, the common biconvex design overlooks off-axis performance, leading to a reduced optical quality in the periphery of the retina in pseudophakic patients compared to the normal phakic eye. In this work, we designed an IOL to provide better peripheral optical quality, closer in that respect to the natural lens, using ray-tracing simulations in eye models. The resulting design was a concave-convex inverted meniscus IOL with aspheric surfaces. The curvature radius of the posterior surface was smaller than that of the anterior surface by a factor that depended on the IOL power. The lenses were manufactured and evaluated in a custom-built artificial eye. Images of a point source and of extended targets were directly recorded at various field angles with both standard and the new IOLs. This type of IOL produces superior image quality in the whole visual field, being a better surrogate for the crystalline lens than the commonly used thin biconvex intraocular lenses.

We report a case of a patient that was implanted with an intracapsular ring during phacoemulsification cataract surgery. Namely, we report on refraction, posterior capsule transparency and IOL ACD and document photographically the appearance of the posterior capsule. It is suggested that the presence of the intracapsular ring has inhibited epithelial cell migration and prevented the formation of posterior capsule opacification (PCO) in the postoperative interval of 7 months. A comparison with the fellow eye of the same patient is made.

A handheld, standalone optical instrument was developed for the in-vivo assessment of the eye’s macular pigment optical density. The instrument is based on the reflectometry method, where the retina is illuminated with light of the appropriate spatial, temporal, and spectral characteristics and the reflected light from the fundus is collected using a high-speed photodetector. The collected light is then analysed and the corresponding value for macular pigment in the eye is computed.

Peripheral refraction is a relevant information in different areas of clinical optics, such as myopia or cataracts. We have developed and validated an optical instrument and a corresponding method for the in-vivo assessment of peripheral defocus and astigmatism from the recording of through-focus double-pass images.

Purpose:To investigate in vitro the accuracy of dynamic contour tonometry, Goldmann applanation tonometry, and Tono-Pen XL in edematous corneas.Methods:Experimental study included 20 freshly enucleated porcine eyes. Epithelium was debrided, and eyes were divided in four groups. Groups were immersed in 35%, 40%, 50%, and 60% glycerin solutions for 3 hours. Subsequently, globes were mounted in a special holder, and their intraocular pressure was hydrostatically adjusted. Intraocular pressure was measured by means of dynamic contour tonometry, Goldmann applanation tonometry, and Tono-Pen XL while adjusting true intraocular pressure to 17, 33, and 50 mm Hg. Ultrasound pachymetry was performed.Results:Mean corneal thickness was 914.5 ± 33.3 μm (730–1015 μm). In true intraocular pressure of 33 mm Hg, Goldmann applanation tonometry and dynamic contour tonometry significantly underestimated true intraocular pressure (mean Goldmann applanation tonometry: 14.7 ± 4.8 mm Hg, p Conclusion:Goldmann applanation tonometry, dynamic contour tonometry, and Tono-Pen XL underestimate intraocular pressure when measured under edematous conditions. Tono-Pen XL showed better accuracy, especially in lower true intraocular pressure. The measurement error increases when true intraocular pressure increases in all three methods.

Purpose To show the importance of measuring the angular distribution of straylight as an in vitro test for intraocular lenses (IOLs). Methods The optical integration method was implemented to measure the point spread function, up to 5.1°, of IOLs immersed in a wet cell. The straylight parameter was calculated as the product of the point spread function by the squared angle. The effect of the scattered light is shown in extended images of a target surrounded by headlamps as glare sources. Three different IOLs were tested: (1) AcrySof IQ SN60WF, monofocal, (2) AcrySof IQ PanOptix, trifocal, and (3) Tecnis Symfony ZRX00, bifocal with extended depth of focus. Measurements were compared to previously reported clinical studies where the same IOL models were implanted. Results The mean amount of scattered light, between 1.0° and 5.1°, generated by each IOLs were, in deg2sr- 1 units: (1) 1.2, (2) 12.1, and (3) 33.4. Lens (3) present a high amount of straylight related to a halo of an approximate diameter of 2°. Conclusions In vitro measurements of the angular distribution of the point spread function of different types of IOLs showed important aspects related to their manufacturing quality. These results are in line with previous clinical findings where glare sensitivity was tested in the same angular range. Translational relevance In vitro measurement of angular dependence of straylight in IOLs, regardless their design, provides a valuable feedback to improve their optical quality. The minimization of the amounts of straylight positively impacts the recurrence of photic phenomena.

PURPOSE: Scattering in the eye occurs mainly at two sites: the eye's optical media and the deeper retinal layers. Although the two phenomena are often treated collectively, their spatial domain of contribution to the double-pass Point Spread Function (PSF) is different: the fundus effect is limited to the narrow and middle part of the PSF whereas scattering in the eye's optics extends also to wide angles. The objective of this work was to determine the domain of contribution at the double-pass PSF of light scattered in the ocular media and the ocular fundus, using simulated and experimental data for two different wavelengths and for two different pigmentations. METHODS: Diffuse reflection was simulated using Monte Carlo simulations for a four-layer retinal fundus model. Four situations were simulated in total for two different choroidal absorptions at two different wavelengths. Light diffusion in the fundus was the only phenomenon considered in the model. The simulations were compared against experimental fundus reflection data obtained in a previous study. RESULTS: The simulations showed that at 560 nm, diffusion in the fundus causes light to extend to a radius of 2°, independently of the choroidal pigmentation, whereas at 650 nm it extends to radii of 4.5° and 4° for low and high choroidal pigmentation respectively. Experimental data showed a similar behaviour at low angles where light diffusion in the fundus is dominant, but different at higher angles due to scattering in the ocular media. CONCLUSION: The spatial contribution of light diffused in the ocular fundus to the PSF was found to be limited to narrower angles compared to that of scattering at the ocular media. The comparison of simulated and optical data showed that beyond 2° at 560 nm and 4–4.5° at 650 nm the only phenomenon contributing to the PSF is scattering in the ocular media, whereas the fundus contribution can be assumed as negligible.

Purpose Straylight refers to an optical phenomenon that takes places in the eye and leads to a deterioration of the retinal image. Past clinical findings suggest an increase of straylight with the eye's axial length, but the aetiology of the phenomenon was unclear. The purpose of this work is to demonstrate, through raytracing, simple geometrical optics, and the well-established inverse-angle square law for the angular distribution of straylight, why straylight increases when a myopic eye is corrected with spectacles. Methods The angular dependence of straylight is investigated using geometrical optics. An expression relating the eye's 2(nd) nodal point, the ocular axial length and the eye's straylight parameter S is found. Subsequently, using a model of the human eye, the location of the 2(nd) nodal point is computed using ray tracing for different axial lengths and refractive corrections. Finally, the results are compared against psychophysical data for the straylight parameter, corrected for the subject's age. Results When correcting axial myopia using spectacles, the eye's 2(nd) nodal point shifts towards the retina and away from the scattering plane, leading to an increase in straylight. Meanwhile, straylight should theoretically decrease in hyperopic eyes. Contact lenses keep the 2(nd) nodal point relative stable, leading to a very minor change in straylight with axial length. Our model has shown good agreement with previously taken straylight measurements in real eyes, explaining the observed change of straylight with ocular axial length. Conclusion We proposed an explanation for the underlying optical mechanism for the clinically observed increase of straylight with axial myopia, when corrected with glasses. Our model predicts that the increase can be as high as 0.12 log units for a myopic eye with 10 dioptres, which agrees with prior observations.

Macular pigment is a yellowish pigment of purely dietary origin, which is thought to have a protective role in the retina. Recently, it was linked to age-related macular degeneration and improved visual function. In this work, we present a method and a corresponding optical instrument for the rapid measurement of its optical density. The method is based on fundus reflectometry and features a photodetector for the measurement of reflectance at different wavelengths and retinal locations. The method has been tested against a commercially available instrument on a group of healthy volunteers and has shown good correlation. The proposed instrument can serve as a rapid, non-midriatic, low-cost tool for the measurement of macular pigment optical density.

Harvey S Uy,1,2 Carolina Tesone-Coelho,3 Harilaos Ginis4 1Peregrine Eye and Laser Institute, Makati, Philippines; 2Department of Ophthalmology and Visual Sciences, University of the Philippines, Manila, Philippines; 3Department of Research and Development, InfiniteVision Optics, Strasbourg, France; 4Research Department, Athens Eye Hospital, Athens, Greece Purpose: Eyes that have undergone phacoemulsification with implantation of a multicomponent intraocular lens (MCIOL) may further undergo an enhancement procedure for correction of residual refractive errors. The enhancement procedure is accomplished by exchanging the front lens used in the primary surgery with another lens containing the correct dioptric power. We evaluated the efficacy and safety of enhancement procedures among eyes that received an MCIOL.Methods: A total of 25 eyes that had undergone phacoemulsification with implantation of an MCIOL were found to have a residual error of refraction (spherical equivalent ≥0.75 D) 3 months after primary cataract surgery, and underwent further enhancement surgery. The main study outcomes were uncorrected and corrected distance visual acuity, subjective refraction, anterior-chamber depth, pachymetry, and endothelial cell count.Results: There was a statistically significant improvement in uncorrected distance visual acuity of approximately two lines after enhancement surgery (0.20±0.20–0.02±0.08 logMAR, P

The purpose of this work was to evaluate peripheral image quality in the pseudophakic eye using computational, physical, and psychophysical methods. We designed and constructed a physical model of the pseudophakic human eye with realistic dimensions using a corneal phantom and a board-only camera that was pivoted around an axis that matched the anatomical center of a human retina, assuming a radius of curvature of 12 mm, while it was submersed in a 23.4 mm long water filled chamber to emulate human ocular axial length. We used this optical setup to perform direct recording of the point spread function (PSF) and the associated retinal images for a commercial intraocular lens (IOL). Additionally, psychophysical tests were carried out to investigate the impact of the off-axis astigmatism in peripheral visual performance, where spectacle-induced astigmatism simulated the pseudophakic conditions in healthy subjects. Our findings using the physical eye model confirm the existence of large amounts of astigmatism in the periphery of the pseudophakic eye. The psychophysical tests revealed a significant reduction of detection sensitivity in the peripheral visual field. The latter suggests that off-axis astigmatism in patients implanted with IOLs may have performance and safety implications for activities requiring efficient peripheral vision.

Fundus reflectometry is a common in-vivo, noninvasive method to estimate the macular pigment optical density (MPOD). The measured density, however, can be affected by the individual’s intraocular scattering. Scattering causes a reduction in the contrast of the fundus image, which in turn leads to an underestimation of the measured density. Intraocular scattering was measured optically in a group of seven young, healthy subjects using the method of optical integration and was subsequently used to correctly estimate the MPOD from fundus images. It was shown that when scattering is not considered, the measured optical density using fundus reflectometry can be underestimated by as high as 16% for our group of subjects.

Purpose.To compare ocular rigidity (OR) and outflow facility (C) in patients with nonproliferative diabetic retinopathy (NPDR) and control subjects.Methods. Twenty-four patients with NPDR (NPDR group) and 24 controls (control group) undergoing cataract surgery were enrolled. NPDR group was further divided into patients with mild NPDR (NPDR1-group) and patients with moderate and/or severe NPDR (NPDR2-group). After cannulation of the anterior chamber, a computer-controlled device was used to infuse saline and increase the intraocular pressure (IOP) in a stepping procedure from 15 to 40 mmHg. Ocular rigidity and outflow facility coefficients were estimated from IOP and volume recordings.Results. Ocular rigidity was 0.0205 μL−1in NPDR group and 0.0202 μL−1in control group (P=0.942). In NPDR1-group, OR was 0.017 μL−1and in NPDR2-group it was 0.025μL−1(P=0.192). Outflow facility was 0.120 μL/min/mmHg in NPDR-group compared to 0.153 μL/min/mmHg in the control group at an IOP of 35 mmHg (P=0.151). There was no difference in C between NPDR1-group and NPDR2-group (P=0.709).Conclusions. No statistically significant differences in ocular rigidity and outflow facility could be documented between diabetic patients and controls. No difference in OR and C was detected between mild NPDR and severe NPDR.

When setting off on a journey of discovery it often helps to have a sense of direction, a particular goal or a coveted treasure that makes all the hardships on the way to get there worthwhile. In science these treasures often come in the form of understanding, built up one tiny gold piece of insight at a time. But unlike the stories of Tolkien, the protagonists of a scientific journey cannot just set out blindly towards a vaguely‐described goal without bothering about things such as finances. Instead, each step along the way must be considered carefully before it hits the ground, while thinking ahead two or three paces, as resources are scarce and funding agencies insist each step should have a reasonable chance of success. Each step may also turn out to be in the wrong direction, or, if you are very lucky, a leap straight for the gold. Consequently these journeys are often slow, with people dedicating an entire PhD to a single step. One can imagine that under these circumstances individual travellers may lose sight of the final goal ahead. But, luckily, in science we do not walk the entire journey by ourselves. As Bernard of Chartres and Isaac Newton both suggested, we are carried on the shoulders of our forebears until it is time to make our own steps, in the hope one of us will eventually reach the treasure of understanding. In that context it is good to stop sometimes and to look at the scenery of where we are now and all the places we may go.

Increased intraocular scatter degrades quality of vision, especially in the presence of glare sources. Standard tests, such as visual acuity, are not well suited to capture this condition. There are specific methods to measure intraocular scatter, but require dedicated instruments. In this work, we propose a method to estimate the amount of scatter by combining to sequential measurements of the contrast sensitivity function for two conditions, with and without a glare source. We applied the approach in a group of young subjects with no know ocular pathology fitted with photographic diffusing filters. The straylight estimates were compared with those provided by two alternative techniques, one based on the compensation comparison method and the other the optical integration. The results obtained with the three approaches were in a good agreement, demonstrating the feasibility of the proposed method.

The 9th European Meeting on Visual Physiological Optics (VPO2018) was held August 29-31, 2018, in Athens, Greece. This issue of the Journal of the Optical Society of America A (JOSA A) is a dedicated feature, including numerous articles that span a large range of visual optics related topics, ranging from geometrical optics to visual psychophysics and from optical metrology to ophthalmic diagnostic technologies. The next VPO meeting will be held August 2020 in Cambridge, UK.

Ioannis G Pallikaris, Nela R Stojanovic, Harilaos S Ginis Institute of Vision and Optics, Department of Medicine, University of Crete, Heraklion, Crete, Greece Purpose: The aim of this study is to demonstrate the functionality of a new design of a thick endocapsular open ring for prevention of anterior capsule opacification (ACO) and posterior capsule opacification (PCO). Setting: The Institute of Vision and Optics, University of Crete and University Hospital of Heraklion, Crete, Greece. Design: Prospective, interventional pilot study. Methods: Fifteen patients (17 eyes) underwent cataract surgery with phacoemulsification. During surgery, a thick endocapsular open ring (peripheral capsule reconstructor) was inserted into the capsular bag, prior to intraocular lens (IOL) implantation. Six different models of IOL were implanted. Postoperatively, the degree of ACO and PCO was evaluated and described as none, mild, moderate, or severe. Results: The mean follow-up period was 30±8.06 months (range: 12–36 months). At the last follow-up, mild PCO was observed in only three eyes and mild ACO in three patients. The centration of IOLs was good in all but one eye, which had a tilted IOL. Conclusion: The results of this pilot study suggest that the implantation of a new design of thick endocapsular open ring is feasible and may contribute to the prevention of PCO and ACO after cataract surgery. Keywords: intraocular implant, cataract, phacoemulsification, silicone

A novel mathematical and physical method of generating complete ocular wavefronts, based on the parametrization and numerical optimization of the discrete cosine spectrum of the phase maps.

Light scattering in the eye affects the quality of vision and its effect increases with aging and related pathologies, such as cataracts. Simulating methods were developed in order to reproduce the effects of this phenomenon. We introduce a statistical model of wavefront perturbations at the pupil plane of the eye that replicates the characteristic angular distribution of the light distribution over the retina. Our approach is based on the parameterization of the discrete cosine spectrum of the wavefront perturbation. The model performance was experimentally validated with a dedicated setup using a liquid crystal on silicon device as a spatial phase modulator. This instrument can be used for further visual experiments with controlled induction of light scattering.

Purpose: A variety of anti-glaucomatous shunt designs have been proposed so far. This study evaluates the feasibility of a novel shunt design, the intra-scleral parathalamus implant (IPI), in a rabbit eye model. Methods: Ten healthy albino rabbits were included. Measurements of the IOP, using TonoPenXL, as well as ocular rigidity (OR) and aqueous outflow facility (AO), using a previously described methodology, were performed in both eyes of each animal. Subsequently, the IPI was implanted at the left eye of all animals whereas the right eye served as control. Measurements of IOP were repeated at weekly intervals for 2 months postoperatively whereas measurements of OR and AO were repeated at the 1st and 2nd postoperative week. Results: The IOP decreased significantly whereas the AO increased significantly postoperatively at the operated eyes. A significant postoperative decrease in OR was also recorded at the operated eyes. Respective differences at the fellow eyes were statistically not significant. Two animals developed postoperative complications and were excluded from follow-up. Conclusions: Results imply that the implantation of the IPI is feasible in rabbit eyes with significant favorable effects on the IOP, AO and OR.

Purpose The intraocular pressure (IOP) is determined by a dynamic equilibrium between the production and outflow of the aqueous humour. The relationship between IOP and the outflow rate through the conventional and unconventional pathway is quantified by the outflow facility coefficient (C). The purpose of this study is to employ a direct (manometric) tonographic technique and determine C as well as its inverse, resistance (R), as a function of IOP in the living human eye. Methods Nineteen cataract patients were enrolled in the study. An intraoperative manometric device was used to measure IOP. After cannulation of the anterior chamber, the IOP was increased by infusion of controlled amounts of saline solution. At 40 mmHg, the infusion stopped, and a pressure sensor recorded the IOP. The measured pressure–volume relationship was considered in order to convert pressure changes to corresponding ocular volume changes. An appropriate mathematical model was applied to calculate C and (its inverse), R. Results The average C was 0.0672 ± 0.0296 μl/min/mmHg at 40 mmHg and 0.2652 ± 0.1164 μl/min/mmHg at 20 mmHg. There was a strong dependence of coefficient C on IOP in all subjects (p

Intraocular scattering affects fundus imaging in a similar way that affects vision; it causes a decrease in contrast which depends on both the intrinsic scattering of the eye but also on the dynamic range of the image. Consequently, in cases where the absolute intensity in the fundus image is important, scattering can lead to a wrong estimation. In this paper, a setup capable of acquiring fundus images and estimating objectively intraocular scattering was built, and the acquired images were then used for scattering compensation in fundus imaging. The method consists of two parts: first, reconstruct the individual’s wide-angle Point Spread Function (PSF) at a specific wavelength to be used within an enhancement algorithm on an acquired fundus image to compensate for scattering. As a proof of concept, a single pass measurement with a scatter filter was carried out first and the complete algorithm of the PSF reconstruction and the scattering compensation was applied. The advantage of the single pass test is that one can compare the reconstructed image with the original one and see the validity, thus testing the efficiency of the method. Following the test, the algorithm was applied in actual fundus images in human eyes and the effect on the contrast of the image before and after the compensation was compared. The comparison showed that depending on the wavelength, contrast can be reduced by 8.6% under certain conditions.

PURPOSE To study the relative impact of genetic and environmental factors on the variability of intraocular scattering within a classical twin study. METHODS A total of 64 twin pairs, 32 monozygotic (MZ) (mean age: 54.9 ± 6.3 years) and 32 dizygotic (DZ) (mean age: 56.4 ± 7.0 years), were measured after a complete ophthalmologic exam had been performed to exclude all ocular pathologies that increase intraocular scatter as cataracts. Intraocular scattering was evaluated by using two different techniques based on a straylight parameter log(S) estimation: a compact optical instrument based in the principle of optical integration and a psychophysical measurement. Intraclass correlation coefficients (ICC) were used as descriptive statistics of twin resemblance, and genetic models were fitted to estimate heritability. RESULTS No statistically significant difference was found for MZ and DZ groups for age (P = 0.203), best-corrected visual acuity (P = 0.626), cataract gradation (P = 0.701), sex (P = 0.941), optical log(S) (P = 0.386), or psychophysical log(S) (P = 0.568), with only a minor difference in equivalent sphere (P = 0.008). Intraclass correlation coefficients between siblings were similar for scatter parameters: 0.676 in MZ and 0.471 in DZ twins for optical log(S); 0.533 in MZ twins and 0.475 in DZ twins for psychophysical log(S). For equivalent sphere, ICCs were 0.767 in MZ and 0.228 in DZ twins. Conservative estimates of heritability for the measured scattering parameters were 0.39 and 0.20, respectively. CONCLUSIONS Correlations of intraocular scatter (straylight) parameters in the groups of identical and nonidentical twins were similar. Heritability estimates were of limited magnitude, suggesting that genetic and environmental factors determine the variance of ocular straylight in healthy middle-aged adults.

We investigated the spatial characteristics of the diffuse light in the eye at two different wavelengths and the extent to which this may affect red-green relative spectral sensitivity. The fundus reflectance of six subjects was measured for different field sizes ranging from a 0.18° to 7.28° radius and for two different wavelengths, 560 and 650 nm. The experimental setup consisted of having an instrument project uniform disks on the fundus and recording their retinal images after a double pass through the eye. Additionally, the relative spectral sensitivity for the same wavelengths was measured using heterochromatic flicker photometry for a stimulus of a 0.4° radius with and without the presence of a synchronously flickering concentric annulus. We concluded that although light backscattered from the fundus contributes to vision, the effect is not strong and can only be observed under appropriate laboratory conditions. This suggests that diffuse light from deeper fundus layers is unlikely to have a practical relevance to vision.