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Purpose: To assess the efficiency and safety of pilocarpine eye drop 1.25% analogue (IRPilo) in comparison with its original brand-name drug (Vuity). Methods: In this non-randomized comparative study, 75 patients with presbyopia aged 40 to 60 years were enrolled. The right eyes of these patients received either IR-Pilo (n = 45) or Vuity (n = 30) and their contralateral eyes served as controls. Refractive errors, distance best-corrected visual acuity (BCVA), near vision, amplitude of accommodation, pupil size, and intraocular pressure (IOP) were measured before and 1 to 2 hours after instillation of the eye drop. Results: The mean refractive error was stable, except for a small myopic shift in the Vuity group. There was no significant change in distance BCVA. Near vision improved significantly in both intervention groups (P < 0.001) with preference for IR-Pilo (4 vs 2.3). Furthermore, a higher amplitude of accommodation and pupil constriction occurred after instillation of both drops, with a higher effect associated with IR-Pilo. However, IOP did not change significantly post intervention. Conclusion: IR-Pilo and Vuity eye drops had comparable results; both were effective and led to stable distance vision and improved near vision. Both ophthalmic drugs were safe and none of them were associated with significant adverse effects.

The BVI ISOPURE® intraocular lens (IOL) (PhysIOL, Liege, Belgium) is a fully refractive, aspherical, monofocal lens based on isofocal technology. Isofocal technology provides cataract patients distance vision quality combined with improved unaided intermediate vision by accentuating the extended depth of field/focus (EDOF) effect whilst inducing minimal photic phenomena.MethodsPubMed, Web of Science, Scopus, and Google Scholar searches were conducted for published research articles featuring the ISOPURE 123 IOL.ResultsExcellent uncorrected and corrected binocular distance visual acuity of at least 20/25 can be achieved; uncorrected binocular intermediate vision of 20/25 or better in 81% and 50% at 80 cm and 66 cm, respectively, and 42% binocular near vision of 20/40 or better can be achieved. The defocus curve showed good visual acuity at far and intermediate distances with a depth of focus value of 1.50 D. Photic phenomena are minimal compared to other EDOF IOLs. Excellent contrast sensitivity was maintained compared to a standard monofocal IOL.ConclusionStudies show that this isofocal optic design IOL provides excellent visual performance for far vision and functional intermediate vision with an increased range of vision with few photic phenomena. This lens is an effective option for providing functional intermediate vision and correcting aphakia.

Abstract Background Uncorrected refractive errors contribute enormously to the burden of avoidable visual impairment worldwide. There is a huge disparity in different parts of the globe in context to spectacle coverage for distance vision. This study was undertaken with objectives of determining prevalence of spectacle coverage, unmet needs and associated factors among adults in a rural community of north India. Methods A community-based cross-sectional study was carried out within selected clusters of Jhajjar district of Haryana. All participants aged > 15 years underwent visual acuity assessment by LogMAR “E” screening chart. Participants with presenting visual acuity 6/12 was computed. These are reported as proportions with 95% confidence intervals. Associated factors with unmet need were determined using bivariable and multivariable logistic regression analysis. Results A total of 6910 participants were examined. The current spectacle use was 7.5% (95% Confidence Interval CI: 6.5, 8.7). The spectacle coverage was found in 33.3% (95% CI: 30.0, 36.7) participants among those in need. The unmet need was found in 10.8% of participants (95% CI: 10.1, 11.6). On multivariable analysis, odds of unmet need was associated with age, gender, level of education and marriage status. The most common barrier for refractive correction was lack of perceived need for refraction and its correction. Conclusion There is substantial unmet need for distance vision spectacles in this population. It is imperative that multi-component intervention be implemented to improve spectacle coverage in this rural north Indian setting.

Background: Uncorrected refractive errors contribute enormously to the burden of avoidable visual impairment worldwide. There is a huge disparity in different parts of the globe in context to spectacle coverage for distance vision. This study was undertaken with objectives of determining prevalence of spectacle coverage, unmet needs and associated factors among adults in a rural community of north India.Methods: A community-based cross-sectional study was carried out within selected clusters of Jhajjar district of Haryana. All participants aged > 15 years underwent visual acuity assessment by LogMAR "E" screening chart. Participants with presenting visual acuity < 6/12 in any eye and all current spectacle users underwent detailed ophthalmic examination and refraction. Additional details about spectacles, barriers for their use and willingness to pay for them were collected. Participants with met and unmet need for spectacle use at visual acuity > 6/12 was computed. These are reported as proportions with 95% confidence intervals. Associated factors with unmet need were determined using bivariable and multivariable logistic regression analysis.Results: A total of 6910 participants were examined. The current spectacle use was 7.5% (95% Confidence Interval CI: 6.5, 8.7). The spectacle coverage was found in 33.3% (95% CI: 30.0, 36.7) participants among those in need. The unmet need was found in 10.8% of participants (95% CI: 10.1, 11.6). On multivariable analysis, odds of unmet need was associated with age, gender, level of education and marriage status. The most common barrier for refractive correction was lack of perceived need for refraction and its correction.Conclusion: There is substantial unmet need for distance vision spectacles in this population. It is imperative that multi-component intervention be implemented to improve spectacle coverage in this rural north Indian setting. [ABSTRACT FROM AUTHOR]

Background/Purpose To evaluate the relationship between refractive error and vision-related quality of life in 16-year-old students in Taiwan. Methods A cross-sectional study was designed for 16-year junior-high-school students in Taiwan. Myopia was defined as a spherical refractive error (SRE) < −0.50 D, hyperopia as SRE > +1.0 D, and emmetropia as SRE −0.5–+1.0 D in the better eye. Vision-related quality of life was assessed using the Taiwan Chinese version of the 25-Item National Eye Institute Visual Functioning Questionnaire. Results Of the 688 participants, 466 (68%) had myopia and 22 (3%) had hyperopia. In logistic-regression models adjusted for gender, parents' education, family income, and parental refractive error, myopia was an independent risk factor of poorer vision-related quality of life for both near vision (odds ratio 1.73, 95% confidence interval 1.22–2.45) and distance vision (odds ratio 3.11, 95% confidence interval 2.23–4.35). Hyperopia was not associated with near- or distance-vision difficulty. Conclusion In this study population, myopia was associated with difficulties in near and distance vision compared to emmetropia. Further studies are needed to confirm our findings in other populations. [ABSTRACT FROM AUTHOR]

A particularly unusual visual system exists in the visually guided aquatic predator, the Sunburst Diving Beetle, Thermonectus marmoratus (Coleoptera: Dytiscidae). The question arises: how does this peculiar visual system function? A series of experiments suggests that their principal eyes (E1 and E2) are highly specialized for hunting. These eyes are tubular and have relatively long focal lengths leading to high image magnification. Their retinae are linear, and are divided into distinct green-sensitive distal and UV and polarization-sensitive proximal portions. Each distal retina, moreover, has many tiers of photoreceptors with rhabdomeres the long axis of which are peculiarly oriented perpendicular to the light path. Based on detailed optical investigations, the lenses of these eyes are bifocal and project focused images onto specific retinal tiers. Behavioral experiments suggest that these larvae approach prey within their eyes' near-fields, and that they can correctly gauge prey distances even when conventional distance-vision mechanisms are unavailable. In the near-field of these eyes object distance determines which of the many retinal layers receive the best-focused images. This retinal organization could facilitate an unusual distance-vision mechanism. We here summarize past findings and discuss how these eyes allow Thermonectus larvae to be such successful predators. [ABSTRACT FROM AUTHOR]

Very few visual systems diverge fundamentally from the basic plans of well-studied animal eyes. However, investigating those that do can provide novel insights into visual system function. A particularly unusual system exists in the principal larval eyes of a visually guided aquatic predator, the sunburst diving beetle, Thermonectus marmoratus (Coleoptera: Dystiscidae). These eyes are characterized by complex layered distal and proximal retinas. We previously reported that their principal eye E2 has a bifocal lens, and previous behavioral experiments suggested that these larvae have a unilateral range-finding mechanism that may involve their bizarre eye organization. In the present study, we expanded our optical measurements and found that: (1) E1 also has a bifocal lens, (2) E1 is best suited for far vision while E2 is best suited for near vision and (3) throughout their typical hunting range, the positions of focused images shift across specific retinal layers. This anatomical and optical organization in principle could support unilateral range finding. Taken together, our findings outline an unusual visual mechanism that is likely to be essential for the extraordinary hunting ability of these larvae. [ABSTRACT FROM AUTHOR]

Grass frogs, Rana pipiens, will detour around a barrier to reach prey on the other side. However, if the distance between prey and barrier is short, frogs attempt to push through the barrier and reach the prey directly. The relationship between the probability of detouring and the distance between prey and barrier is the same whether the frog's starting position is 4 cm or 8 cm from the barrier. This suggests that frogs measure the absolute separation between the two objects. To discover whether the retinal elevation of the bottom of the barrier contributes to measuring this distance, the relationship between the frequency of detouring and barrier-prey distance was examined in several experiments in which the retinal position of the bottom of the barrier was manipulated. No evidence was obtained that the barrier's retinal elevation helps in gauging distance. On the other hand, retinal elevation influences strongly how far a frog lunges to reach its prey. It is suggested that different cues to distance are applied to the two classes of object because, under natural circumstances, it is difficult to judge where a barrier emerges from the ground. A barrier may be hard to detect below the horizon because of the low contrast between it and the ground, or because vegetation and ground litter mask where the barrier meets the ground. In contrast, the prey's movements make it easily detectable against a stationary background and the prey's short height means that partial occlusion will have little effect on its apparent vertical position in the visual field. [ABSTRACT FROM AUTHOR]

This paper addresses two questions. 1. Does Schistocerca gregaria detect edges which are defined solely by velocity-contrast, that is by the difference in the image speeds generated by an object and its background when the locust moves? 2. Is the locust's ability to measure the distance of a target by motion parallax independent of the relative motion between target and back-ground? A locust walking on a circular platform was surrounded by a stationary cylinder which was lined with an irregular texture. Against this background, the insect viewed 3 stationary, equidistant targets. One target was black, one grey and the last was textured like the cylinder. Peers and jumps were aimed preferentially at the textured and black targets showing that targets can be detected by virtue of their velocity-contrast with the background. When textured targets were wide, jumps were seen to be aimed at the targets' edge. To assess whether velocity-contrast between target and background distorts distance-estimates, we used jump-velocity as a measure of apparent distance and examined how it varied with different arrangements of target and background. When a textured background is close to a target or the target is very wide, velocity contrast is small. The locust's jump-velocity is then 10% greater than when velocity-contrast is increased by making the background distant or the target narrow. This suggests that the locust is efficient at separating signals encoding absolute motion from those encoding relative motion. [ABSTRACT FROM AUTHOR]

Based on the initial movement of falling prey, hunting archerfish select a C-start that turns them right to where their prey is going to land and lends the speed to arrive simultaneously with prey. Our companion study suggested that the information sampled in less than 100 ms also includes the initial height of falling prey. Here, we examine which cues the fish might be using to gauge height so quickly. First, we show that binocular cues are not required: C-starts that either could or could not have used binocular information were equally fast and precise. Next, we explored whether the fish were using simplifying assumptions about the absolute size of their prey or its distance from a structured background. However, experiments with unexpected changes from the standard conditions failed to cause any errors. We then tested the hypothesis that the fish might infer depth from accommodation or from cues related to blurring in the image of their falling prey. However, the fish also determined the height of 'fake flies' correctly, even though their image could never be focused and their combined size and degree of blurring should have misled the fish. Our findings are not compatible with the view that archerfish use a flexible combination of cues. They also do not support the view that height is gauged relative to structures in the vicinity of starting prey. We suggest that these fish use an elaborate analysis of looming to rapidly gauge initial height., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2018. Published by The Company of Biologists Ltd.)