Nearwork-induced transient myopia in preadolescent Hong Kong Chinese

PURPOSE. To compare the magnitude and time course of nearwork-induced transient myopia (NITM) in preadolescent Hong Kong Chinese myopes and emmetropes. METHOD. Forty-five Hong Kong Chinese children, 35 myopes and 10 emmetropes aged 6 to 12 years (median, 7.5), monocularly viewed a letter target through a Badal lens for 5 minutes at either 5.00- or 2.50-D accommodative demand, followed by 3 minutes of viewing the equivalent target at optical infinity. Accommodative responses were measured continuously with a modified, infrared, objective open-field autorefractor. Accommodative responses were also measured for a countercondition: viewing of a letter target for 5 minutes at optical infinity, followed by 3 minutes of viewing the target at a 5.00-D accommodative demand. The results were compared with tonic accommodation and both subject and family history of refractive error. RESULTS. Retinal-blur-driven NITM was significantly greater in Hong Kong Chinese children with myopic vision than in the emmetropes after both near tasks, but showed no significant dose effect. The NITM was still evident 3 minutes after viewing the 5.00-D near task for 5 minutes. The magnitude of NITM correlated with the accommodative drift after viewing a distant target for more than 4 minutes, but was unrelated to the subjects' or family history of refractive error. CONCLUSIONS. In a preadolescent ethnic population with known predisposition to myopia, there is a significant posttask blur-driven accommodative NITM, which is sustained for longer than has previously been found in white adults.

Optical and structural ocular changes during incipient presbyopia

The primary aim of this thesis was to investigate the in vivo ocular morphological and contractile changes occurring within the accommodative apparatus prior to the onset of presbyopia, with particular reference to ciliary muscle changes with age and the origin of a myopic shift in refraction during incipient presbyopia. Commissioned semi-automated software proved capable of extracting accurate and repeatable measurements from crystalline lens and ciliary muscle Anterior Segment Optical Coherence Tomography (AS-OCT) images and reduced the subjectivity of AS-OCT image analysis. AS-OCT was utilised to document longitudinal changes in ciliary muscle morphology within an incipient presbyopic population (n=51). A significant antero-inwards shift of ciliary muscle mass was observed after 2.5 years. Furthermore, in a subgroup study (n=20), an accommodative antero-inwards movement of ciliary muscle mass was evident. After 2.5 years, the centripetal response of the ciliary muscle significantly attenuated during accommodation, whereas the antero-posterior mobility of the ciliary muscle remained invariant. Additionally, longitudinal measurement of ocular biometry revealed a significant increase in crystalline lens thickness and a corresponding decrease in anterior chamber depth after 2.5 years (n=51). Lenticular changes appear to be determinant of changes in refraction during incipient presbyopia. During accommodation, a significant increase in crystalline lens thickness and axial length was observed, whereas anterior chamber depth decreased (n=20). The change in ocular biometry per dioptre of accommodation exerted remained invariant after 2.5 years. Cross-sectional ocular biometric data were collected to quantify accommodative axial length changes from early adulthood to advanced presbyopia (n=72). Accommodative axial length elongation significantly attenuated during presbyopia, which was consistent with a significant increase in ocular rigidity during presbyopia. The studies presented in this thesis support the Helmholtz theory of accommodation and despite the reduction in centripetal ciliary muscle contractile response with age, primarily implicate lenticular changes in the development of presbyopia.

The influence on unaided vision of age, pupil diameter and spherocylindrical refractive error

Background - The aim was to derive equations for the relationship between unaided vision and age, pupil diameter, iris colour and sphero-cylindrical refractive error. Methods - Data were collected from 663 healthy right eyes of white subjects aged 20 to 70 years. Subjective sphero-cylindrical refractive errors ranged from -6.8 to +9.4 D (mean spherical equivalent), -1.5 to +1.9 D (orthogonal component, J0) and -0.8 to 1.0 D (oblique component, J45). Cylinder axis orientation was orthogonal in 46 per cent of the eyes and oblique in 18 per cent. Unaided vision (-0.3 to +1.3 logMAR), pupil diameter (2.3 to 7.5 mm) and iris colour (67 per cent light/blue irides) was recorded. The sample included mostly females (60 per cent) and many contact lens wearers (42 per cent) and so the influences of these parameters were also investigated. Results - Decision tree analysis showed that sex, iris colour, contact lens wear and cylinder axis orientation did not influence the relationship between unaided vision and refractive error. New equations for the dependence of the minimum angle of resolution on age and pupil diameter arose from step backwards multiple linear regressions carried out separately on the myopes (2.91.scalar vector +0.51.pupil diameter -3.14 ) and hyperopes (1.55.scalar vector + 0.06.age – 3.45 ). Conclusion - The new equations may be useful in simulators designed for teaching purposes as they accounted for 81 per cent (for myopes) and 53 per cent (for hyperopes) of the variance in measured data. In comparison, previously published equations accounted for not more than 76 per cent (for myopes) and 24 per cent (for hyperopes) of the variance depending on whether they included pupil size. The new equations are, as far as is known to the authors, the first to include age. The age-related decline in accommodation is reflected in the equation for hyperopes.

Is pupil diameter influenced by refractive error?

Purpose: To investigate the relationship between pupil diameter and refractive error and how refractive correction, target luminance, and accommodation modulate this relationship. Methods: Sixty emmetropic, myopic, and hyperopic subjects (age range, 18 to 35 years) viewed an illuminated target (luminance: 10, 100, 200, 400, 1000, 2000, and 4100 cd/m2) within a Badal optical system, at 0 diopters (D) and −3 D vergence, with and without refractive correction. Refractive error was corrected using daily disposable contact lenses. Pupil diameter and accommodation were recorded continuously using a commercially available photorefractor. Results: No significant difference in pupil diameter was found between the refractive groups at 0 D or −3 D target vergence, in the corrected or uncorrected conditions. As expected, pupil diameter decreased with increasing luminance. Target vergence had no significant influence on pupil diameter. In the corrected condition, at 0 D target vergence, the accommodation response was similar in all refractive groups. At −3 D target vergence, the emmetropic and myopic groups accommodated significantly more than the hyperopic group at all luminance levels. There was no correlation between accommodation response and pupil diameter or refractive error in any refractive group. In the uncorrected condition, the accommodation response was significantly greater in the hyperopic group than in the myopic group at all luminance levels, particularly for near viewing. In the hyperopic group, the accommodation response was significantly correlated with refractive error but not pupil diameter. In the myopic group, accommodation response level was not correlated with refractive error or pupil diameter. Conclusions: Refractive error has no influence on pupil diameter, irrespective of refractive correction or accommodative demand. This suggests that the pupil is controlled by the pupillary light reflex and is not driven by retinal blur.

Evaluating techniques to improve visual performance with and assessment of premium intraocular lenses

Premium Intraocular Lenses (IOLs) such as toric IOLs, multifocal IOLs (MIOLs) and accommodating IOLs (AIOLs) can provide better refractive and visual outcomes compared to standard monofocal designs, leading to greater levels of post-operative spectacle independence. The principal theme of this thesis relates to the development of new assessment techniques that can help to improve future premium IOL design. IOLs designed to correct astigmatism form the focus of the first part of the thesis. A novel toric IOL design was devised to decrease the effect of toric rotation on patient visual acuity, but found to have neither a beneficial or detrimental impact on visual acuity retention. IOL tilt, like rotation, may curtail visual performance; however current IOL tilt measurement techniques require the use of specialist equipment not readily available in most ophthalmological clinics. Thus a new idea that applied Pythagoras’s theory to digital images of IOL optic symmetricality in order to calculate tilt was proposed, and shown to be both accurate and highly repeatable. A literature review revealed little information on the relationship between IOL tilt, decentration and rotation and so this was examined. A poor correlation between these factors was found, indicating they occur independently of each other. Next, presbyopia correcting IOLs were investigated. The light distribution of different MIOLs and an AIOL was assessed using perimetry, to establish whether this could be used to inform optimal IOL design. Anticipated differences in threshold sensitivity between IOLs were not however found, thus perimetry was concluded to be ineffective in mapping retinal projection of blur. The observed difference between subjective and objective measures of accommodation, arising from the influence of pseudoaccommodative factors, was explored next to establish how much additional objective power would be required to restore the eye’s focus with AIOLs. Blur tolerance was found to be the key contributor to the ocular depth of focus, with an approximate dioptric influence of 0.60D. Our understanding of MIOLs may be limited by the need for subjective defocus curves, which are lengthy and do not permit important additional measures to be undertaken. The use of aberrometry to provide faster objective defocus curves was examined. Although subjective and objective measures related well, the peaks of the MIOL defocus curve profile were not evident with objective prediction of acuity, indicating a need for further refinement of visual quality metrics based on ocular aberrations. The experiments detailed in the thesis evaluate methods to improve visual performance with toric IOLs. They also investigate new techniques to allow more rapid post-operative assessment of premium IOLs, which could allow greater insights to be obtained into several aspects of visual quality, in order to optimise future IOL design and ultimately enhance patient satisfaction.

A longitudinal study of accommodative changes in biometry during incipient presbyopia

PURPOSE: To profile accommodative biometric changes longitudinally and to determine the influence of age-related ocular structural changes on the accommodative response prior to the onset of presbyopia. METHODS: Twenty participants (aged 34-41 years) were reviewed at six-monthly intervals over two and a half years. At each visit, ocular biometry was measured with the LenStar biometer (www.Haag-Streit.com) in response to 0.00, 3.00 and 4.50 D stimuli. Accommodative responses were measured by the WAM 5500 Auto Ref/Keratometer (www.grandseiko.com). RESULTS: During accommodation, anterior chamber depth reduced (F = 29, p < 0.001), whereas crystalline lens thickness (F = 39, p < 0.001) and axial length (F = 5.4, p = 0.009) increased. The accommodative response (F = 5.5, p = 0.001) and the change in anterior chamber depth (F = 3.1, p = 0.039), crystalline lens thickness (F = 3.0, p = 0.042) and axial length (F = 2.5, p = 0.038) in response to the 4.50 D accommodative target reduced after 2.5 years. However, the change in anterior chamber depth (F = 2.2, p = 0.097), crystalline lens thickness (F = 1.7, p = 0.18) and axial length (F = 1.0, p = 0.40) per dioptre of accommodation exerted remained invariant after 2.5 years. The increase in disaccommodated crystalline lens thickness with age was not significantly associated with the reduction in accommodative response (R = 0.32, p = 0.17). CONCLUSION: Despite significant age-related structural changes in disaccommodated biometry, the change in biometry per dioptre of accommodation exerted remained invariant with age. The present study supports the Helmholtz theory of accommodation and suggests an increase in lenticular stiffness is primarily responsible for the onset of presbyopia.

Clinical evaluation of the Shin-Nippon SRW-5000 autorefractor in adults:an update

Purpose: The Shin-Nippon SRW-5000 is an open view autorefractor that superseded the Canon R-1 autorefractor in the mid-1990s and has been used widely in optometry and vision science laboratories. It has been used to measure refractive error, accommodation responses both statically and dynamically, off-axis refractive error, and adapted to measure pupil size. This paper presents an overview of the original 2001 clinical evaluation of the SRW-5000 in adults (Mallen et al., Ophthal Physiol Opt 2001; 21: 101) and provides an update on the use and modification of the instrument since the original publication. Recent findings: The SRW-5000 instrument, and the family of devices which followed, have shown excellent validity, repeatability, and utility in clinical and research settings. The instruments have also shown great potential for increased research functionality following a number of modifications. Summary: The SRW-5000 and its derivatives have been, and continue to be, of significant importance in our drive to understand myopia progression, myopia control techniques, and oculomotor function in human vision.

Hiánygazdaság - többletgazdaság. Tanulmány a piac elméletéről - I. rész = Shortage economy surplus economy. A study on market theory I

A főáramlat közgazdászai elismerik, hogy a szocialista rendszert a krónikus hiány jellemezte, de úgy vélik, hogy a kapitalista rendszerben - kisebb vagy nagyobb ingadozások közepette - piaci egyensúly uralkodik. Ezzel szemben a tanulmány két piaci állapotot állít egymással szembe. Az egyikben dominálnak a túlkeresleti jelenségek, bár előfordulnak túlkínálati jelenségek is, ezt nevezi a szerző hiánygazdaságnak. A másikban dominálnak a túlkínálati jelenségek, bár előfordulnak túlkeresleti jelenségek is, amit a szerző többletgazdaságnak nevez. A hiánygazdaságot magyarázó tényezőket a szerző korábbi munkái írták le. A jelen tanulmány I. része azokat a mechanizmusokat mutatja be, amelyek a kapitalizmus keretei között létrehozzák a többletgazdaságot: a korlátozott verseny, a schumpeteri "teremtő rombolás", a vállalat törekvése biztonsági tartalékok kiépítésére és a növekvő skálahozadék. Foglalkozik azokkal a jelenségekkel, amelyek fékezik a kereslet és az árak alkalmazkodását. Külön fejezet tárgyalja a többlet mérésének (és ezzel szoros összefüggésben a fogalmak szigorú definícióinak) nehézségeit. ______ Mainstream economists recognize that the socialist system was marked by chronic shortage, but they consider that the capitalist system exhibits market equilibrium, give or take some greater or lesser fluctuations. This study, however, contrasts two market states. One is dominated by phenomena of excess demand, though instances of excess supply appear as well; this the author calls a shortage economy. The other is dominated by phenomena of excess supply, though instances of excess demand appear as well; this the author terms a surplus economy. The author has described in earlier works the factors explaining the shortage economy. Part I of the study presents the mechanisms generating a surplus economy under capitalism: imperfect competition, Schumpeterian "creative destruction" , the efforts of firms to build up safety reserves, and increasing economies of scale. It also covers phenomena that curb accommodation of demand and prices. Discussed in a separate chapter are the difficulties of measuring surplus (and closely tied with this, of strictly defining the concepts).

Organizational response to employment under the ADA of workers with psychiatric disabilities: Four case studies

Title 1 of the Americans with Disabilities Act (ADA) requires all employers, public and private, with more than fifteen employees to provide reasonable accommodation to qualified individuals with disabilities if the accommodation would, within limits, allow the individual to perform the essential functions of the job. Seven years after Congress enacted the law and five years after the initial provisions became effective, little information is available about the experience of organizations faced with requests for workplace accommodation.^ The question addressed in this study is: How are organizations responding to the ADA mandate to fit individuals with psychiatric disabilities in the workplace? The data sources are three organizations that allowed access to this sensitive information, and a fourth that had two disability discrimination charges filed against it.^ A brute-force case method approach applied to the four organizations yields the following information: Attorneys are hesitant to allow inquiry into company policy owing to fear of litigation; workers are not disclosing and requesting accommodation; tacit accommodation of long-standing employees appears to be a regular practice; knowledge of the intent of the ADA makes a difference in terms of equality of treatment; and insensitivity to employee privacy results in an adversarial situation.^ Implications are relevant to the need to improve lines of communication between human resource, EEO, supervisory, and legal staff; consequences of failure to address accommodations on an explicit level; need for better understanding of the availability and use of outside resources for achieving accommodation; and improvement of self-advocacy and disclosure by the employees with disabilities. ^

What individuals with rheumatic diseases know about the Americans with Disabilities Act: A survey

Individuals with rheumatic diseases often have disabilities which limit one or more major life activity. Common disabilities among individuals with rheumatic illnesses such as chronic pain, hand deformities, and fatigue may be hidden. With a hidden disability, an individual may be unaware that he or she could qualify as disabled under the Americans with Disabilities Act (ADA). The ADA provides for reasonable accommodation for qualified individuals with disability related limitations. Accommodations under the ADA are designed to remove barriers preventing full participation in society, including employment, for individuals with disability related limitations.^ The primary objective of this study was to determine the knowledge level of individuals with rheumatic conditions about the Americans with Disabilities Act (ADA). One hundred and seven individuals with various rheumatic illnesses participated in this survey. The forty question survey included questions about type of rheumatic condition, employment, pain level, and knowledge of the ADA. Results of this study show that individuals with rheumatic conditions are more familiar with general information about the ADA and less familiar with specific information. The longer an individual has been diagnosed with a rheumatic condition the more he or she knows about the ADA. Common sources of information about the ADA are media and networking with others, rather than health care professionals. The recommendation for occupational therapists is to include education about the ADA as an integral component of treatment for all individuals with rheumatic conditions. ^

The relationship between classroom interactions and exclusionary discipline as a social practice: A critical microethnograhy

Exclusionary school discipline results in students being removed from classrooms as a consequence of their disruptive behavior and may lead to subsequent suspension and/or expulsion. Literature documents that nondominant students, particularly Black males, are disproportionately impacted by exclusionary discipline, to the point that researchers from a variety of critical perspectives consider exclusionary school discipline an oppressive educational practice and condition. Little or no research examines specific teacher-student social interactions within classrooms that influence teachers’ decisions to use or not use exclusionary discipline. Therefore, this study set forth the central research question: In relation to classroom interactions in alternative education settings, what accounts for teachers’ use or non-use of exclusionary discipline with students? A critical social practice theory of learning served as the framework for exploring this question, and a critical microethnographic methodology informed the data collection and analysis. ^ Criterion sampling was used to select four classrooms in the same alternative education school with two teachers who frequently and two who rarely used exclusionary discipline. Nine stages of data collection and reconstructive data analysis were conducted. Data collection involved video recorded classroom observations, digitally recorded interviews of teachers and students discussing selected video segments, and individual teacher interviews. Reconstructive data analysis procedures involved hermeneutic inferencing of possible underlying meanings, critical discourse analysis, interactive power analysis and role analysis, thematic analysis of the interactions in each classroom, and a final comparative analysis of the four classrooms. ^ Four predominant themes of social interaction (resistance, conformism, accommodation, and negotiation) emerged with terminology adapted from Giroux’s (2001) theory of resistance in education and Third Space theory (Gutiérrez, 2008). Four types of power (normative, coercive, interactively established contracts, and charm), based on Carspecken’s (1996) typology, were found in the interactions between teacher and students in varying degrees for different purposes. ^ This research contributes to the knowledge base on teacher-student classroom interactions, specifically in relation to exclusionary discipline. Understanding how the themes and varying power relations influence their decisions and actions may enable teachers to reduce use of exclusionary discipline and remain focused on positive teacher-student academic interactions. ^

A New Generation of Cruise Ships

The giant new cruise ships entering service are distinguished not only by their size but also by the new standards of accommodation for the average passenger that the increased amount of space on board makes possible. Amenities include a major percentage of cabins with private verandas, extensive physical fitness facilities, more inviting dining arrangements, and the use of décor and space planning in an attempt to recover some of the intimacy lost as cruise ships have increased in size. The author reviews how each of the major cruise lines has taken advantage of the challenges and opportunities that the creation of these ships has represented, and presents an overview of the largest new cruise ships that have entered service in the past several years.

Overcoming The Impotency Of Marketing

In his dialogue titled - Overcoming The Impotency Of Marketing - K. Michael Haywood, Assistant Professor, School of Hotel and Food Administration, University of Guelph, originally reveals: “Many accommodation businesses have discovered that their marketing activities are becoming increasingly impotent. To overcome this evolutionary stage in the life cycle of marketing, this article outlines six principles that will re-establish marketing's vitality.” “The opinion of general managers and senior marketing, financial, and food and beverage managers is that the marketing is not producing the results it once did and is not working as it should,” Haywood advises. Haywood points to price as the primary component hospitality managers use to favor/adjust their marketability. Although this is an effective tool, the practice can also erode profitability and margin he says. Haywood also points at recession as a major factor in exposing the failures of marketing plans. He adds that the hotel manager cannot afford to let this rationale go unchallenged; managers must take measures to mitigate circumstances that they might not have any control over. Managers must attempt to maintain profitability. “In many hotels, large corporate accounts or convention business generates a significant proportion of occupancy. Often these big buyers dictate their terms to the hotels, especially the price they are prepared to pay and the service they expect,” Haywood warns. This dynamic is just another significant pitfall that challenges marketing strategy. The savvy marketing technician must be aware of changes that occur in his or her marketplace, Haywood stresses. He offers three specific, real changes, which should be responded to. “To cope with the problems and uncertainties of the hotel business during the remainder of the decade, six components need to be developed if marketing impotency is to be overcome,” says Haywood in outlining his six-step approach to the problem. Additionally, forward thinking cannot be over-emphasized. “A high market share is helpful in general, but an even more crucial factor is careful consideration of the market sectors in which the company wants to operate,” your author advises. “Taking tactical initiatives is essential. Successful hotels act; unsuccessful ones react. The less successful marketing operations tend to be a hive of frantic activity. Fire-fighting is the normal way of life in such organizations, Haywood observes. “By contrast, successful firms plan and execute their tactical marketing activity with careful timing and precision so as to create the maximum impact,” he extends in describing his fruitful marketing arabesque.

Effects of real -time captioning and sign language interpreting on the learning of college students who are deaf or hard of hearing

College personnel are required to provide accommodations for students who are deaf and hard of hearing (D/HoH), but few empirical studies have been conducted on D/HoH students as they learn under the various accommodation conditions (sign language interpreting, SLI, real-time captioning, RTC, and both). Guided by the experiences of students who are D/HoH at Miami-Dade College (MDC) who requested RTC in addition to SLI as accommodations, the researcher adopted Merten’s transformative-emancipatory theoretical framework that values perceptions and voice of students who are D/HoH. A mixed methods design addressed two research questions: Did student learning differ for each accommodation? What did students experience while learning through accommodations? Participants included 30 students who were D/HoH (60% women). They represented MDC’s majority minority population: 10% White (non-Hispanic), 20% Black (non-Hispanic, including Haitian/Caribbean), 67% Hispanic, and 3% other. Hearing loss, ranged from severe-profound (70%) to mild-moderate (30%). All were able to communicate with American Sign Language: Learning was measured while students who were D/HoH viewed three lectures under three accommodation conditions (SLI, RTC, SLI+RTC). The learning measure was defined as the difference in pre- and post-test scores on tests of the content presented in the lectures. Using repeated measure ANOVA and ANCOVA, confounding variables of fluency in American Sign Language and literacy skills were treated as covariates. Perceptions were obtained through interviews and verbal protocol analysis that were signed, videotaped, transcribed, coded, and examined for common themes and metacognitive strategies. No statistically significant differences were found among the three accommodations on the learning measure. Students who were D/HoH expressed thoughts about five different aspects of their learning while they viewed lectures: (a) comprehending the information, (b) feeling a part of the classroom environment, (c) past experiences with an accommodation, (d) individual preferences for an accommodation, (e) suggestions for improving an accommodation. They exhibited three metacognitive strategies: (a) constructing knowledge, (b) monitoring comprehension, and (c) evaluating information. No patterns were found in the types of metacognitive strategies used for any particular accommodation. The researcher offers recommendations for flexible applications of the standard accommodations used with students who are D/HoH.

Lucumí (Yoruba) culture in Cuba: A reevaluation (1830s -1940s)

The status, roles, and interactions of three dominant African ethnic groups and their descendants in Cuba significantly influenced the island's cubanidad (national identity): the Lucumís (Yoruba), the Congos (Bantú speakers from Central West Africa), and the Carabalís (from the region of Calabar). These three groups, enslaved on the island, coexisted, each group confronting obstacles that threatened their way of life and cultural identities. Through covert resistance, cultural appropriation, and accommodation, all three, but especially the Lucumís, laid deep roots in the nineteenth century that came to fruition in the twentieth. During the early 1900s, Cuba confronted numerous pressures, internal and external. Under the pretense of a quest for national identity and modernity, Afro-Cubans and African cultures and religion came under political, social, and intellectual attack. Race was an undeniable element in these conflicts. While all three groups were oppressed equally, only the Lucumís fought back, contesting accusations of backwardness, human sacrifice, cannibalism, and brujería (witchcraft), exaggerated by the sensationalistic media, often with the police's and legal system's complicity. Unlike the covert character of earlier epochs' responses to oppression, in the twentieth century Lucumí resistance was overt and outspoken, publically refuting the accusations levied against African religions. Although these struggles had unintended consequences for the Lucumís, they gave birth to cubanidad's African component. With the help of Fernando Ortiz, the Lucumí were situated at the pinnacle of a hierarchical pyramid, stratifying African religious complexes based on civilizational advancement, but at a costly price. Social ascent denigrated Lucumí religion to the status of folklore, depriving it of its status as a bona fide religious complex. To the present, Lucumí religious descendants, in Cuba and, after 1959, in many other areas of the world, are still contesting this contradiction in terms: an elevated downgrade.