Modified forms of Tscherning ellipses.

Third-order equations are well known for determining sagittal and tangential powers of a thin lens, corresponding to an eye rotating behind a lens to view objects away from the optical axis of the lens. These equations are referenced to the back surface of the lens and do not take into account the peripheral thickness of the lens. They do not give the same results as finite raytracing at small angles in which powers are referenced to the vertex sphere, which is the same distance from the centre-of-rotation for all object angles. Modified forms of the third-order sagittal and tangential image vergence error equations are developed to overcome the discrepancies. These are used to determine Tscherning ellipses for zero oblique astigmatism and zero mean oblique power error. While solutions to oblique astigmatism are not affected by the modifications, there are considerable changes to mean oblique error solutions.

Portable device for presbyopia correction with optoelectronic lenses driven by pupil response.

A novel portable device has been developed and built to dynamically, and automatically, correct presbyopia by means of a couple of opto-electronics lenses driven by pupil tracking. The system is completely portable providing with a high range of defocus correction up to 10 D. The glasses are controlled and powered by a smartphone. To achieve a truly real-time response, image processing algorithms have been implemented in OpenCL and ran on the GPU of the smartphone. To validate the system, different visual experiments were carried out in presbyopic subjects. Visual acuity was maintained nearly constant for a range of distances from 5 m to 20 cm.

Temporal trends in the prevalence of spectacle use and spectacle coverage in India.

BACKGROUND: This study aims to assess the temporal trends in the prevalence of spectacle use and spectacle coverage for refractive errors in population-based studies conducted during 2011-2012 and 2017 among those aged ≥ 40 years in the state of Telangana, India. An intervention in the form of 10 vision centres and a secondary centre was established in one district (Khammam) after the 2011-2012 study and another district (Warangal) was left to secular trends. METHODS: In both the studies, multi-stage cluster random sampling methodology was used to select the participants. In addition to a clinical examination, a questionnaire was used for collecting information on current and previous use of spectacles, type of spectacles and details of the spectacle providers. The same questionnaire was used in both the studies. RESULTS: In total, 2,485 participants were examined in the 2011-2012 study and 2,711 participants were examined in the 2017 study in Khammam. Similarly, 2,438 and 2,646 participants were examined in Warangal in the two studies, respectively. In Khammam, the age and gender-adjusted prevalence of current spectacle use increased from 30.0 per cent (95% CI 28.2-31.9) to 34.8 per cent (95% CI 33.0-36.6) in the 2011-2012 and 2017 studies, respectively (p < 0.01). However, in the Warangal district, the age and gender-adjusted prevalence of current spectacle use declined from 32.8 per cent (95% CI 31.0-34.7) to 27.6 per cent (95% CI 25.9-29.3) during the 2011-2012 and 2017 studies, respectively (p < 0.01). In Khammam, the spectacle coverage increased from 26.9 per cent to 35.6 per cent, but it declined from 43.8 per cent to 35.7 per cent in Warangal between the studies in 2011-2012 and 2017. CONCLUSIONS: An increase in spectacle use and coverage was observed in Khammam where the secondary centre and vision centres were established, compared to Warangal where there was no such intervention. The results suggest a positive impact of the intervention in the Khammam district and suggest replication of the model to address the burden of uncorrected refractive errors.

Global trends in myopia management attitudes and strategies in clinical practice - 2019 Update.

PURPOSE: A survey in 2015 identified a high level of eye care practitioner concern about myopia with a reported moderately high level of activity, but the vast majority still prescribed single vision interventions to young myopes. This research aimed to update these findings 4 years later. METHODS: A self-administrated, internet-based questionnaire was distributed in eight languages, through professional bodies to eye care practitioners globally. The questions examined: awareness of increasing myopia prevalence, perceived efficacy of available strategies and adoption levels of such strategies, and reasons for not adopting specific strategies. RESULTS: Of the 1336 respondents, concern was highest (9.0 ±â€¯1.6; p < 0.001) in Asia and lowest (7.6 ±â€¯2.2; p < 0.001) in Australasia. Practitioners from Asia also considered their clinical practice of myopia control to be the most active (7.7 ±â€¯2.3; p < 0.001), the North American practitioners being the least active (6.3 ±â€¯2.9; p < 0.001). Orthokeratology was perceived to be the most effective method of myopia control, followed by pharmaceutical approaches and approved myopia control soft contact lenses (p < 0.001). Although significant intra-regional differences existed, overall, most practitioners did not consider single-vision distance under-correction to be an effective strategy for attenuating myopia progression (79.6 %), but prescribed single vision spectacles or contact lenses as the primary mode of correction for myopic patients (63.6 ±â€¯21.8 %). The main justifications for their reluctance to prescribe alternatives to single vision refractive corrections were increased cost (20.6 %) and inadequate information (17.6 %). CONCLUSIONS: While practitioner concern about myopia and the reported level of activity have increased over the last 4 years, the vast majority of eye care clinicians still prescribe single vision interventions to young myopes. With recent global consensus evidence-based guidelines having been published, it is hoped that this will inform the practice of myopia management in future.

Smart-Glasses: Exposing and Elucidating the Ethical Issues.

The objective of this study is to provide an overview over the ethical issues relevant to the assessment, implementation, and use of smart-glasses. The purpose of the overview is to facilitate deliberation, decision making, and the formation of knowledge and norms for this emerging technology. An axiological question-based method for human cognitive enhancement including an extensive literature search on smart-glasses is used to identify relevant ethical issues. The search is supplemented with relevant ethical issues identified in the literature on human cognitive enhancement (in general) and in the study of the technical aspects of smart-glasses. Identified papers were subject to traditional content analysis: 739 references were identified of which 247 were regarded as relevant for full text examinations, and 155 were included in the study. A wide variety of ethical issues with smart-glasses have been identified, such as issues related to privacy, safety, justice, change in human agency, accountability, responsibility, social interaction, power and ideology. Smart-glasses are envisioned to change individual human identity and behavior as well as social interaction. Taking these issues into account appears to be relevant when developing, deliberating, deciding on, implementing, and using smart-glasses.

[Requirements for low vision magnification aids in age-related macular degeneration: Data from the Tübingen low vision clinic (comparison of 2007-2011 with 1999-2005)]. / Bedarf an vergrößernden Sehhilfen bei altersbedingter Makuladegeneration: Daten der Tübinger Sehbehindertenambulanz (Vergleich der Jahre 2007 bis 2011 mit 1999 bis 2005).

BACKGROUND: The purpose of this study was to investigate if there has been a change in requirements for low vision magnification aids in recent years. PATIENTS AND METHODS: The collective data from age-related macular degeneration (AMD) patients from the Tübingen low vision clinic from the years 2007-2011 were compared with the patient collective from the years 1999-2005. Magnification needs and the prescribed magnifying aids for reading in the categories magnifying spectacles, hand-held magnifiers, monocular telescopes, electronic magnifiers and electronic reading devices were evaluated. In addition patients from 2010 and 2011 were divided into dry and neovascular AMD and the prescribed magnification aids were compared for these AMD forms. RESULTS: There was no significant change in in the prescribed magnification reading aids for AMD patients between the years 1999-2005 and 2007-2011. An electronic magnifier was prescribed most often (both collectives 43 %), followed by hand-held magnifiers (32 and 29.5 %, respectively) and magnifying spectacles (17 and 18.8 %, respectively). Also the magnifying needs and mean age of the AMD patients did not change significantly between the two periods (2007-2011 versus 1999-2005). The detailed analysis for dry and neovascular AMD for the years 2010 and 2011 showed no significant differences for the most commonly prescribed low vision aids. The prescription of low vision aids is not influenced by the AMD classification (dry or neovascular), only by the magnification needs. CONCLUSION: There is an unchanged and still high demand for rehabilitation aids of AMD patients, for dry as well as for neovascular AMD even after the introduction of anti-vascular endothelial growth factor (anti-VEGF) therapy.

Personalizing of spectacles.

Spectacles are vital for correcting vision. Individuals who need vision correction can choose to wear spectacles or contact lenses. Alternatively, they may choose to have a vision-correcting operation. Therefore, researchers focus on vision science and spectacle design. Although some studies have compared spectacles and contact lenses for better visual quality, there is no consensus regarding which are better for the correction of vision. With the development of technology and the improvement of living standards, the design and production of spectacles will focus on personalized style, lenses, and frames. In this paper, we introduced trends in spectacles and studies of the relationship between frame sizes and face sizes, attempting to provide a feasible program for the personalization of spectacles-the Personalized Spectacles Program. Furthermore, certain limitations, such as non-personalized and misused spectacles, which have elevated the importance of the design and production of personalized spectacles were discussed.

Grinding it out: wavefront spectacle lens in clinical practice.

This is the first literature report of a series of Zeiss iScription process wave guided spectacles (glasses) compared with conventional non-wave guided glasses. We designed a prospective pilot study of our initial clinical experience. Fifty patients with wavefront and fifty non-wavefront glasses were compared for lens changes made for comfort or visual clarity after initial manufacture and fitting. Minimum follow up was 90 days. Forty-six (92%) of the wavefront glasses required no modifications after initial delivery compared to 42 (86%) of non-wavefront glasses. There was a trend for conventional glasses to be returned more often than wavefront glasses but the difference was not statistically significant.

The impact of continuing professional development on ophthalmic dispensing of progressive addition lenses in the Asia-Pacific region.

BACKGROUND: Discrepancies exist in optometric education, practice and regulation across the Asia-Pacific region and the competence of optometric practitioners in adopting new lens technologies may vary widely. Over the past 10 years, a continuing professional development program, Varilux Academy Asia-Pacific (VAAP), was implemented and conducted in countries across the Asia-Pacific region to improve practitioners' understanding of optometric fitting principles, with special emphasis on progressive addition lenses (PAL). The aim was to demonstrate the effectiveness of VAAP and to compare the competence of practitioners across the Asia-Pacific region in new lens fitting technologies. METHODS: From 2002 to 2008, all VAAP participants from 12 countries across Asia-Pacific were invited to complete a pre- and a post-program competency test and a post-program survey. RESULTS: A total of 5658 practitioners were trained, and 69.9 per cent (n = 3,957) of participants completed the pre- and post-program competency test; 80.9 per cent (n = 4,580) of participants completed the post-program survey. There was a significant improvement in competency after VAAP (mean change = 19.4 per cent ± 3.3, p < 0.01). Before VAAP was conducted the mean competency score was significantly lower in developing countries compared with developed countries (mean score of developed countries = 50.6 ± 10.3, mean score of developing countries = 45.0 ± 7.8, p < 0.05). After VAAP, these differences were not significant. Confidence in fitting PAL improved by 27.1 per cent. Most participants (91.6 per cent) intended to fit more PAL and 96.8 per cent of participants rated the program as excellent or good. CONCLUSION: Our findings highlight the need for further continuing education of practitioners across the Asia-Pacific region. The results of the training course indicate that, across Asia-Pacific, continuing education courses in ophthalmic optics and dispensing encompassing modern lens design and best practice fitting principles are warranted.

The disengage deficit in hemispatial neglect is restricted to between-object shifts and is abolished by prism adaptation.

We sought to determine the effects of prism adaptation on peripherally cued visual attention shifting in patients with spatial neglect, using a task devised by Egly et al. (J Exp Psychol Gen 123:161-177, 1994) based on the classic Posner paradigm. This task allowed a comparison of "within-object" versus "between-object" attention shifts. A display was presented containing two parallel outline rectangles, and subjects were asked to make rapid responses to a target, which would appear at one end of one of the rectangles. The target location was pre-cued with 75% validity: on invalid trials attention was directed either to the other end of the same rectangle, or to the other rectangle. Healthy subjects and right-hemisphere patients without neglect showed a left-right symmetrical pattern, with a larger validity effect when required to shift attention between rectangles, thus indicating a greater difficulty of attention-shifting between than within the respective shapes. The neglect patients showed the typical leftward "disengage deficit" previously observed in neglect, but only for attention shifts between objects, indicating that the effect is object-based rather than purely spatial. A comparison of vertical and horizontal shift costs showed that this attention-shifting deficit for left-hemifield target stimuli was directional rather than hemifield-based: it was absent for vertical shifts of attention within the left hemifield. Finally, we found that prism adaptation abolished the disengage deficit. We found no effects of prism adaptation in the control subjects. We argue that prism adaptation has a powerful effect on one of the fundamental manifestations of the neglect syndrome.

Newly designed ergonomic surgical binocular telescope with angulated optic axis.

OBJECTIVE: Magnification by surgical loupes has the distinct merits of agility and nimbleness in observation, a wide stereo base effectuating superior depth sensation, and light augmentation by an objective lens that is larger than the pupil. However, continuous use of these loupes causes neck strain for surgeons as a result of flexion posture and fatigue. To minimize the strain and fatigue and maximize the advantages and performance of binocular telescopes, we have developed a novel optical design. METHODS: To allow observation of the operative field with the surgeon's neck and eye in a straight position, the light path of the telescopes was angulated downward with roof prisms. For maximum image quality, Keplerian real-image optics were adopted. RESULTS: The optics, finishing of the lens, and assembly were perfected through practical trials of more than 500 procedures over a period of 3 years. CONCLUSION: The new ergonomically designed optics provide excellent image quality comparable to standing microscopes in the low to medium range of magnification, while effectively reducing the neck flexion of surgeons working in the operative field below and relieving the surgeon's fatigue during hours of continuous use.

Progress in the spectacle correction of presbyopia. Part 2: Modern progressive lens technologies.

The first installment of this two-part series reviewed the fundamental optical principles and early development work associated with progressive lenses. Recent progress made in advancing the state of the art in progressive lenses will now be presented, with particular emphasis on 'free-form' progressive lenses and the application of 'wavefront' technology in progressive lens design. Because several fundamental concepts were developed in the first paper that will serve as the basis for discussions presented in this paper, including the basic optics and mathematics of progressive lens surfaces, the reader is strongly encouraged to review the companion paper.

Progress in the spectacle correction of presbyopia. Part 1: Design and development of progressive lenses.

Most of the commercial advances in the spectacle correction of presbyopia continue to occur in progressive lens design, which has been the focus of intense research and development over the past 60 years by major spectacle lens manufacturers. While progressive lens design and manufacturing techniques have advanced at a steady pace, recent progress in 'free-form' lens surfacing has opened up many exciting possibilities that will in all likelihood bring about a paradigm shift in the current model of progressive lens fabrication and distribution. The first installment of this two-part series will review the fundamental optical principles and early development work associated with progressive lenses.

Prism adaptation in the rehabilitation of patients with visuo-spatial cognitive disorders.

PURPOSE OF REVIEW: The traditional focus of neurorehabilitaion has been on the patients' attention on their deficit, such that they should become aware of their problems and gain intentional control of compensatory strategies (descending approach). We review prism adaptation as one of the approaches that emphasize ascending rather than descending strategies to the rehabilitation of visuo-spatial disorders. The clinical outcome of prism adaptation highlights the need for a theoretical reconsideration of some previous stances to neurological rehabilitation. RECENT FINDINGS: Recent years have given rise to a growing body of experimental studies showing that the descending strategy is not always optimal, especially when higher-level cognition is affected by the patients' condition. Ascending approaches have, for example, used visuo-manual adaptation for the rehabilitation of visuo-spatial deficits. A simple task of pointing to visual targets while wearing prismatic goggles can produce remarkable improvements of various aspects of unilateral neglect. SUMMARY: The neural mechanisms underpinning visuo-manual plasticity can be viewed as a powerful rehabilitation tool that produces straightforward effects not only on visual and motor parameters, but on visuo-spatial, attentional and higher cognitive neurological functions. The use of prism adaptation therapy in neglect and other visuo-spatial disorders has just started to reveal its potential, both at a practical and theoretical level.