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Purpose Age‐related macular degeneration (AMD) is a major cause of vision loss. This study investigated whether performing clinical audit and receiving analytical performance feedback altered documentation of the AMD care provided by optometrists. Methods Australian optometrists were recruited and completed a survey about their demographics and confidence in AMD care, and a three‐month audit of their practice records using an AMD audit tool (termed the pre‐audit evaluation). After receiving analytical feedback, participants identified areas for improvement and re‐audited their practices after three months to analyse changes in performance (termed the post‐audit evaluation). Paired t‐tests and Wilcoxon signed‐rank tests, as appropriate, were used to compare pre‐ and post‐audit data. Results Twenty optometrists, most practising in Victoria, Australia, completed the study. Participants primarily worked in corporate practice and/or rural settings and had a range of optometric experience (2–40 years). At baseline, participants felt confident in their: knowledge of AMD risk factors (65%), advice to patients about these factors (55%) and management of earlier stages of AMD (55%). Each clinician completed (median [IQR]): 15 [IQR: 10–19] and 12 [IQR: 8–16] audits of unique patient records, pre‐ and post‐audit, respectively. Post‐audit, average record documentation (per optometrist) improved for asking about: AMD family history (94% to 100%, p = 0.03), smoking status (21% to 58%, p < 0.01), diet (11% to 29%, p < 0.01) and nutritional supplementation (20% to 51%, p < 0.01). For clinical examination, compliance with documenting pinhole visual acuity, performing an in‐office Amsler grid (upon indication) and using optical coherence tomography improved post‐audit (p < 0.05). Accuracy of severity documentation improved for earlier stages of AMD (p < 0.05). For earlier stages of AMD, documentation of counselling about modifiable risk factors significantly improved post‐audit (p < 0.05). Aspects well‐performed pre‐audit that did not change included documenting: medical histories (100% at both time points, p = 0.06) and retinal imaging (77% at both time points, p = 0.97). Conclusions Self‐audit with analytical feedback improved clinical record documentation of: AMD risk factors, clinical examination, AMD severity classification and management advice. These findings support a role for audit to improve optometric clinical care of AMD, as evidenced by improved documentation of the AMD care delivered.

The aim was to investigate the understanding of Australian optometrists in relation to myopia, its natural history and associations with vision-threatening ocular disease, self-reported clinical diagnosis and management approaches for childhood myopia, engagement with adult caregivers, and utilisation of information to guide practice.An online survey was distributed to Australian optometrists (n = 4,124). Respondents provided information about their demographics (for example, gender, age, practice location and modality), myopia knowledge, self-reported practice behaviours relating to childhood myopia, the information and evidence base used to guide their practice, and perceived extent of adult caregiver engagement in making management decisions for myopic children.Completed surveys were returned by 239 optometrists (six per cent completed response rate). Most respondents demonstrated knowledge of the association between high myopia and retinal breaks, retinal detachment and primary open-angle glaucoma. Optometrists used a range of techniques to diagnose childhood myopia, with a preference for non-cycloplegic refractive measures. The most common approaches to management were single-vision distance and progressive addition spectacle lenses, despite most optometrists identifying orthokeratology, low-dose (0.01%) topical atropine and soft peripheral defocus contact lenses as three potentially more effective therapeutic interventions for modifying childhood myopia progression. Almost 90 per cent of respondents considered increasing time spent outdoors to be beneficial for reducing the rate of myopia progression. The main sources of information used to guide clinical practice were continuing education conferences and events, systematic reviews, and personal experience. Respondents perceived adult caregivers to generally be involved in myopia management decisions, and considered all aspects of myopia education as important.Current optometric practices reflect the inconclusive nature of several key aspects of the evidence for childhood myopia management. Australian optometrists appear aware of emerging evidence, but are not routinely adopting measures that have not yet received regulatory approval for modulating childhood myopia progression. Clinical guidelines may be of value for assisting practitioners in making clinical decisions based upon the current, best-available research evidence.

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:\ud \ud To assess whether blue-light filtering spectacle lenses impart effects on visual function, provide protection to the macula, or both. We will also examine potential effects on the sleep-wake cycle.

Background An intraocular lens (IOL) is a synthetic lens that is surgically implanted within the eye following removal of the crystalline lens, during cataract surgery. While all modern IOLs attenuate the transmission of ultra-violet (UV) light, some IOLs, called blue-blocking or blue-light filtering IOLs, also reduce short-wavelength visible light transmission. The rationale for blue-light filtering IOLs derives primarily from cell culture and animal studies, which suggest that short-wavelength visible light can induce retinal photoxicity. Blue-light filtering IOLs have been suggested to impart retinal protection and potentially prevent the development and progression of age-related macular degeneration (AMD). We sought to investigate the evidence relating to these suggested benefits of blue-light filtering IOLs, and to consider any potential adverse effects. Objectives To assess the effects of blue-light filtering IOLs compared with non-blue-light filtering IOLs, with respect to providing protection to macular health and function. Search methods We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 9); Ovid MEDLINE; Ovid Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov and the ICTRP. The date of the search was 25 October 2017. Selection criteria We included randomised controlled trials (RCTs), involving adult participants undergoing cataract extraction, where a blue-light filtering IOL was compared with an equivalent non-blue-light filtering IOL. Data collection and analysis The prespecified primary outcome was the change in distance best-corrected visual acuity (BCVA), as a continuous outcome, between baseline and 12 months of follow-up. Prespecified secondary outcomes included postoperative contrast sensitivity, colour discrimination, macular pigment optical density (MPOD), proportion of eyes with a pathological finding at the macula (including, but not limited to the development or progression of AMD, or both), daytime alertness, reaction time and patient satisfaction. We evaluated findings related to ocular and systemic adverse effects.Two review authors independently screened abstracts and full-text articles, extracted data from eligible RCTs and judged the risk of bias using the Cochrane tool. We reached a consensus on any disagreements by discussion. Where appropriate, we pooled data relating to outcomes and used random-effects or fixed-effect models for the meta-analyses. We summarised the overall certainty of the evidence using GRADE. Main results We included 51 RCTs from 17 different countries, although most studies either did not report relevant outcomes, or provided data in a format that could not be extracted. Together, the included studies considered the outcomes of IOL implantation in over 5000 eyes. The number of participants ranged from 13 to 300, and the follow-up period ranged from one month to five years. Only two of the studies had a trial registry record and no studies referred to a published protocol. We did not judge any of the studies to have a low risk of bias in all seven domains. We judged approximately two-thirds of the studies to have a high risk of bias in domains relating to 'blinding of participants and personnel' (performance bias) and 'blinding of outcome assessment' (detection bias).We found with moderate certainty, that distance BCVA with a blue-light filtering IOL, at six to 18 months postoperatively, and measured in logMAR, was not clearly different to distance BCVA with a non-blue-light filtering IOL (mean difference (MD) -0.01 logMAR, 95% confidence interval (CI) -0.03 to 0.02, P = 0.48; 2 studies, 131 eyes).There was very low-certainty evidence relating to any potential inter-intervention difference for the proportion of eyes that developed late-stage AMD at three years of follow-up, or any stage of AMD at one year of follow-up, as data derived from one trial and two trials respectively, and there were no events in either IOL intervention group, for either outcome. There was very low-certainty evidence for the outcome for the proportion of participants who lost 15 or more letters of distance BCVA at six months of follow-up; two trials that considered a total of 63 eyes reported no events, in either IOL intervention group.There were no relevant, combinable data available for outcomes relating to the effect on contrast sensitivity at six months, the proportion of eyes with a measurable loss of colour discrimination from baseline at six months, or the proportion of participants with adverse events with a probable causal link with the study interventions after six months.We were unable to draw reliable conclusions on the relative equivalence or superiority of blue-light filtering IOLs versus non-blue-light filtering IOLs in relation to longer-term effects on macular health. We were also not able to determine with any certainty whether blue-light filtering IOLs have any significant effects on MPOD, contrast sensitivity, colour discrimination, daytime alertness, reaction time or patient satisfaction, relative to non-blue-light filtering IOLs. Authors' conclusions This systematic review shows with moderate certainty that there is no clinically meaningful difference in short-term BCVA with the two types of IOLs. Further, based upon available data, these findings suggest that there is no clinically meaningful difference in short-term contrast sensitivity with the two interventions, although there was a low level of certainty for this outcome due to a small number of included studies and their inherent risk of bias. Based upon current, best-available research evidence, it is unclear whether blue-light filtering IOLs preserve macular health or alter risks associated with the development and progression of AMD, or both. Further research is required to fully understand the effects of blue-light filtering IOLs for providing protection to macular health and function.

PURPOSE The aim of this study was to compare the self-reported clinical practice behaviours of optometrists in Australia and the United Kingdom (UK) with respect to the diagnosis and management of dry eye disease (DED). We also sought to examine whether the reported practices of clinicians in each region were consistent with current evidence-based recommendations for DED. METHODS An online survey was distributed to optometrists (Australia, n = 654; UK, n = 1006). Respondents provided information about practice modality, years of optometric experience, preferred diagnostic and management strategies (stratified by DED severity) and the information/evidence base used to guide patient care. RESULTS A total of 317 completed surveys were received (response rates, Australia: 21%, UK: 17%). Optometrists in both regions demonstrated similarly strong knowledge of tear film assessment and adopted both subjective and objective techniques to diagnose DED. Patient symptoms were considered the most important, valuable and commonly performed assessment by both Australian and UK respondents. UK practitioners valued and utilised conjunctival signs and tear meniscus height assessments more than Australian optometrists (p < 0.05), who placed relatively greater emphasis on sodium fluorescein tear break-up time to diagnose DED (p < 0.05). Clinicians in both locations tailored DED therapy to severity. While practitioners in both regions predominantly managed mild DED with eyelid hygiene and tear supplementation, Australian optometrists indicated prescribing topical corticosteroid therapy significantly more often than UK practitioners for moderate (14% vs 6%) and severe (52% vs 8%) disease (p < 0.05). The major source of information used to guide practitioners' dry eye management practices was continuing education conferences. CONCLUSIONS This study highlights a range of parallels and divergences in dry eye clinical practice between Australian and UK optometrists. Our data identify both areas of strength in the adoption of evidence-based practice, as well as some potential to improve international translation of dry eye research evidence into practice.

Purpose We consider whether quantification of ocular bulbar redness, using image processing of relative Red-channel activity (Red-value), can be applied to a clinical sample and how this approach compares to an automated bulbar redness grading technique (Oculus Keratograph 5M, R-scan). Methods Red-values from dry eye patients (n = 25) were determined using image processing of digital photographs over the nasal bulbar conjunctiva. Red-values were compared with subjective grades from six clinicians who graded the images using the IER scale. We considered the level of agreement between the Red-value and automated bulbar redness scores from the commercial instrument (R-scan). Scoring variability for each technique was assessed using the geometric coefficient of variation (gCoV, %). Agreement between techniques was considered with Bland-Altman analyses. Results Red-values showed a strong linear relationship (R2 = 0.99) to the R-scan. The Red-value had least variability (gCoV = 0.97%, 95% CI: 0.76–1.35%). The IER grade showed a linear relationship with Red-value (R2 = 0.99), bound by a floor effect; it did not discriminate changes in redness below a threshold of 1.75 units (Red-value = 33.0%), after which it paralleled the redness returned by the R-scan. Intra-method variability for the redness returned by the R-scan (gCoV = 9.84%, 95% CI: 7.60–13.94%) and IER grades (gCoV = 7.30%, 95% CI: 1.73–10.31%) was similar (p > 0.05). Bland-Altman analysis showed the R-scan was consistently biased towards lower absolute redness scores than the IER. Conclusions Digital imaging processing, using relative Red-channel activity, was the least variable of the three techniques. The R-scan and IER showed similar intra-observer variability. The linear relationship between R-scan and Red-value suggests that the R-scan could be derived using similar methods.

Age-related macular degeneration (AMD) is the leading cause of irreversible visual impairment in developed countries. In the absence of effective treatments to slow AMD progression, it is predicted that the prevalence of AMD will double over the next 20 years. One area of significant interest is the potential role that nutrition may play in preventing and/or delaying the progression of AMD. Specifically, is there any benefit in oral antioxidant and/or mineral supplementation? This review critically evaluates the currently available evidence relating to nutrition and AMD, with particular reference to the key findings of two large National Eye Institute-sponsored clinical studies, namely, the Age-Related Eye Disease Study (AREDS) and AREDS2. Topical controversies relating to nutrition and AMD are considered and analyzed in the context of the published literature to guide practitioners through assessing the merit, or otherwise, of common claims. This article provides a foundation for clinicians to provide informed advice to AMD patients based on available research evidence.

Importance Cataract surgery, with intraocular lens (IOL) implantation, is the most common ocular surgical procedure worldwide. It has been suggested that IOLs that selectively attenuate short wavelength visible light (blue light–filtering IOLs) may be beneficial for macular health. Whether blue light–filtering IOLs impart retinal photoprotection is of public health relevance, particularly in the context of aging demographics and the increasing global prevalence of age-related macular degeneration. This review analyzes and interprets the key findings, including consideration of the implications for practice and future research, of a 2018 Cochrane systematic review that evaluated the efficacy and safety of blue light–filtering IOLs for providing protection to macular health and function. Observations The Cochrane systematic review included 51 randomized controlled trials that were performed in 17 countries. The trials involved adults undergoing cataract surgery in which a blue light–filtering IOL was compared with an equivalent non-blue light–filtering IOL. Study follow-up periods ranged from 1 month to 5 years. Together, these studies considered clinical outcomes in more than 5000 eyes. There was limited ability to combine data across trials (to draw overall conclusions) because of the use of different measurement techniques for outcomes, incomplete reporting of data, and/or varied follow-up periods. We identified substantial shortcomings in the internal validity of many of the included studies, particularly regarding trial design, conduct, and reporting. We propose several avenues for improving the rigor of potential future research in the field, including developing a core set of outcome measures, the inclusion of sample size calculations, the masking of trial participants and outcome assessors, and prospective clinical trial registration. Conclusions and Relevance Using blue light–filtering IOLs to impart benefits to the macula is currently not supported by the best available clinical research evidence, and it is important that clinicians are mindful of this evidence limitation when adopting these devices in clinical practice.

Purpose Tobacco smoking and nutrition are key lifestyle factors with long-term effects on eye health. However, little is known about patients’ perceptions and experiences in these areas in relation to the care received from optometrists. The main aim was to survey patients’ perceptions and prior experience regarding the role of optometrists in enquiring and providing advice about tobacco smoking and nutrition. Methods An anonymous, paper-based survey was distributed to a convenience sample of 225 adults attending the University of Melbourne eye care clinic. Respondents provided demographic and other information (age, sex, length of time since last eye examination, country of most recent eye examination, smoking status and intake of nutritional supplements) and indicated their level of agreement (using a five-step Likert scale) with a series of statements relating to the care provided by optometrists in the areas of health, smoking and nutrition. The statements were designed to assess the perceived scope of practice of optometrists and the extent to which patients expect, and feel comfortable, discussing these issues with their optometrist. Results 220 completed surveys were returned. Most respondents (>80%) agreed that they visit their optometrist to quantify their refractive error and to examine their eye health. About two-thirds of respondents indicated that they expect their optometrist to ask about their general health, with almost half expecting their optometrist to communicate with their general medical practitioner. Approximately one-third of respondents indicated having been routinely questioned about their smoking status, diet and nutritional supplement intake by their optometrist. This was despite about half expecting their optometrist to question them about these factors and almost three out of four respondents indicating that they felt comfortable talking with their optometrist about these lifestyle behaviours. Conclusions This study provides novel insight into patients’ perceptions and experience with optometric practice in the areas of tobacco smoking and nutrition. The majority of respondents expected their optometrist to examine their eye health, ask them about their smoking and diet habits, and indicated feeling comfortable discussing these topics with their primary eye care provider. These findings suggest that brief advice interventions relating to tobacco use and diet are likely to be acceptable to deliver in optometry practice.

Dry eye disease (DED) is a common, multifactorial disease of the tears and anterior ocular surface. The clinical diagnosis of DED is complex, requiring the consideration of both patient symptoms and signs, which can be apparently contradictory. Misdiagnosis can lead to suboptimal clinical management. Studies of the practice behaviors of optometrists suggest that there is the potential to improve the translation of research evidence relating to the diagnosis of DED into primary ophthalmic care. This review describes an evidence-based, pragmatic approach to the contemporary clinical diagnosis of DED, as a means for guiding best practice for the care of dry eye patients.

Dry eye disease (DED) is a highly prevalent chronic ocular disorder that can lead to significant discomfort and visual disturbance. It is a potentially debilitating condition that can have significant negative impact on quality of life. A diverse range of management options exists for DED, including tear supplement products, anti-inflammatory agents, immunomodulators, punctal occlusive devices, and environmental modifiers. Although the availability of a variety of treatment approaches provides clinical flexibility and can enable individualized care, it can also complicate clinical management decisions and lead to variability in the nature of the clinical care provided to patients. By considering two dry eye case scenarios, this review evaluates the currently available evidence relating to DED therapy to describe a pragmatic clinical approach to best-practice management of dry eye patients.

ObjectiveThe primary aim of this study was to examine the self-reported, routine clinical practice behaviors of Australian optometrists with respect to advice regarding smoking, diet and nutritional supplementation. The study also sought to assess the potential influence of practitioner age, gender, practice location (major city versus regional), therapeutic-endorsement status and personal nutritional supplementation habits upon management practices in these areas.MethodsA survey was electronically distributed to Australian optometrists (n = 4,242). Respondents anonymously provided information about their personal demographics and lifestyle behaviors (i.e., age, gender, practice location, therapeutic-endorsement status, smoking status, nutritional supplement intake) and routine patient management practices with respect to advice across three domains: smoking, diet and nutritional supplementation. Multivariate logistic regression analyses were performed to assess for potential effects of the listed factors on practitioner behavior.ResultsA total of 283 completed surveys were received (completed survey response rate: 6.7%). Fewer than half of respondents indicated routinely asking their patients about smoking status. Younger practitioners were significantly (p < 0.05) less likely to enquire about patients' smoking behaviors, but this did not extend to counseling for smoking cessation. Almost two-thirds of respondents indicated routinely counseling patients about diet. About half of practitioners specified routinely asking their patients about nutritional supplement intake; this form of questioning was significantly more likely if the respondent was female (p < 0.05). Practitioners who recommended nutritional supplements most commonly did so for age-related macular degeneration (91.2%) and dry eye disease (63.9%). The primary source of evidence used to guide practitioners' nutrition-related patient management was reported to be peer-reviewed publications.ConclusionsThese findings demonstrate that there are no clear predictors of practitioner behavior across the three domains. Overall, this study suggests that there is scope for Australian optometrists to improve their routine engagement by questioning patients, as well as providing evidence-based clinical advice, about smoking status, diet and nutritional supplement behaviors, being key modifiable lifestyle risk factors with long-term implications for eye health.

In a scenario set to be played out across the country with increasing frequency over the coming years, an optometrist discusses the management options available to an elderly patient diagnosed with...

Objective The aim of this study was to investigate the personal nutrition – related attitudes and behaviors of Australian optometrists and, in particular, their understanding of the evidence relating to the merit of specific dietary supplements, as applicable to their own health. Methods An online survey was distributed to optometrists registered in Australia (N = 4242). Respondents anonymously provided information regarding their demographic characteristics (age, sex, practice location and modality), diet and lifestyle behaviors (assessment of self-perceived diet quality, smoking status), and nutritional supplement intake (including the rationale for consumption). Results Completed surveys were received from 283 practitioners. Although most respondents considered themselves to eat a healthy, balanced diet, approximately 75% indicated taking nutritional supplements in the preceding year. The four most common supplements were fish oil/ω-3 (62%), multivitamins (54%), vitamin C (30%), and vitamin D (29%). In addition to vitamin D, which was typically recommended by a general medical practitioner for an established deficiency, the other three supplement categories were consumed on the basis of the respondents' self-assessment and decision. Analyses of the motivations for taking these supplements highlighted a significant misunderstanding of the evidence; furthermore, these practitioners appeared to base their personal behaviors on this misinterpretation. Conclusions These findings demonstrate scope for optometrists to enhance their critical thinking and/or understanding of the available evidence relating to the merit, or otherwise, of nutritional supplementation in managing their own health, and more broadly, improving their understanding of what a healthy diet is and its role in eye health.

Purpose: To evaluate the relation between measures of corneal power and refractive error after photorefractive keratectomy (PRK) by applying fast Fourier transform (FFT) to computerized corneal topography data. Setting: Corneal Diseases and Excimer Laser Ginic, Sunderland Eye Infirmary, Sunderland, England, and University of Dundee Department of Ophthalmology, Dundee, Scotland. Methods: Twenty-six left eyes of consecutive patients treated by PRK with a VISX Twenty-Twenty excimer laser were retrospectively analyzed. Preoperative and 3, 6, and 12 month postoperative data were studied. Changes in corneal parameters derived from corneal topography data using the FFT were compared with changes in refractive status vectors (spherical equivalent and astigmatic cosine and sine values). Result: Although highly correlated ( r 2 = 0.8839), the change in FFT-derived corneal spherical equivalent underestimated the change in refractive spherical equivalent by 25.5% over the 12 month follow-up. Decentration, measured by the 1-cycle FFT harmonic, increased significantly from a mean preoperative value of 0.12 mm ± 0.07 (SD) to 0.51 ± 0.35 mm 12 months postoperatively. Conclusions: The FFT is a powerful method for extracting clinically meaningful descriptors from corneal topography data; however, care must be taken when interpreting refractive changes from corneal data.

Purpose: To test the hypothesis that the bow-tie corneal topography pattern results from corneal asphericity in the presence of astigmatism. Methods: Astigmatic color-coded power maps using different shape factors were computer generated. Each simulation was based on the calculation of dioptric power at 20 points along each of 180 hemimeridia, for a total of 3600 points. The calculations were made independent of the capture or measurement of videokeratographs. These simulations were compared to power maps taken from clinical records. Results: A shape factor of 1.00 resulted in a spherocylinder color-coded map with straight-edged sectors of power. The familiar bow-tie pattern was generated using an elliptical model with a shape factor of less than 1.00. This pattern was reversed by modeling the cornea as an oblate ellipsoid using a shape factor greater than 1.00. Conclusions: By simple alteration of the amount of corneal asphericity through manipulation of the shape factor, computer simulation showed that this surface characteristic is responsible for the bow-tie pattern observed in corneal topography power maps.

This article reviews the optical principles of computer-assisted videokeratoscopy (CVK) and provides a guide to the differences between short and long working distance systems. The description of the corneal surface involves a number of complex issues which have yet to be adequately resolved and the importance of alignment and reference axis assumptions to CVK is discussed. With the increasing clinical use of such systems, the debate of such issues has meaning, not just in the research environment but also in routine clinical practice. A number of applications are illustrated.

Purpose. The aims of this study were to investigate the clinical practices of Australian optometrists as related to the diagnosis, quantification, and management of dry eye and to assess whether these are consistent with research evidence and current guidelines. Methods. An online survey was distributed to registered optometrists (n = 654). Respondents provided information regarding their preferred diagnostic procedures and management strategies for dry eye, practice modality, year of commencing practice, and whether they possessed an interest in dry eye. Results. Respondents (n = 144) used multiple procedures for diagnosis. Recording patient symptoms ranked as the most important, most valuable, and most commonly used technique. The main objective tests were fluorescein-assisted tear breakup time, corneal fluorescein staining, and meibomian gland evaluation. Optometrists with an interest in dry eye more frequently used lissamine green, phenol red test, interference fringes, and tear osmolarity than nonspecialist practitioners. Dry eye treatment varied with severity. The mainstay of therapy was nonpreserved lubricants and eyelid hygiene; more practitioners recommended topical corticosteroids, systemic omega-3 fatty acid supplementation and increased dietary intake of omega-3 fatty acids for moderate and severe disease, respectively. The primary sources of information used to guide practitioners’ management were derived from continuing education conferences. Conclusions. This study indicates that although Australian optometrists use subjective and objective diagnostic tests and stratify treatment based on dry eye severity, there is a lack of uniformity regarding diagnostic testing, infrequent use of standardized grading scales, and significant variability in clinical care. These findings highlight the potential to improve the translation of dry eye research evidence and evidence-based guidelines into Australian optometric practice. (Optom Vis Sci 2013;90:1385Y1395)

Background: Graphical display of the many thousands of data points generated by corneal topography systems has progressed from three-dimensional wire representations, through curvature and power maps, to three-dimensional subtraction models. Standard colour-coded corneal ‘topographic’ maps may be misinterpreted as representing corneal profile instead of a form of corneal power. A variety of two- and three-dimensional output methods for displaying corneal topography data are demonstrated. Method: Axial colour-coded isodioptric maps were obtained with the MasterVue Ultra corneal topography system. Separate software was written to access the data files to enable construction of alternative display forms, that is, instantaneous power maps and various colour-coded three-dimensional models. Results: The relative advantages and disadvantages of various methods for viewing corneal topography measurements are demonstrated for data taken from the clinical records of two subjects. Conclusion: Newer methods for displaying corneal topography data enable the visualisation of the differences between representations of power and those of profile. The different display methods have their own advantages and limitations which make them more appropriate in certain applications and less so in others.

Using computer-assisted videokeratoscopy we measured corneal astigmatism and compared these results over a range of corneal zone diameters with total ocular astigmatism derived by subjective refraction. Videokeratoscopes permit a more detailed analysis of the power distribution within a given corneal surface area, enabling comparison to the total astigmatism for equivalent aperture sizes. Although there were significant individual variations, the group average data supports the traditional view of a linear relation between corneal and total astigmatism. This was true across the range of apertures tested from 2 to 7 mm, with the coordinates of the relation being consistent with that of the modified Javal's rule; namely a slope of 1 and an intercept of approximately 0.50 D against-the-rule residual astigmatism.

EDITOR: In stating the case for a specific use of the term ‘evidence’ in evidence‐based practice (EBP) to mean external research evidence,2012 I suggested that to do otherwise is potentially confus...

BACKGROUND: The clinical interpretation of corneal topography power maps has progressed through the development of both qualitative pattern classification systems and a range of quantitative descriptors. Although a number of different indices have been described, they do not all possess obvious clinical utility. METHODS/RESULTS: Fourier series analysis decomposes any circumferential fluctuations in corneal power into various components that have direct clinical correlates. The zero frequency and two-cycle components, which represent spherical equivalent and regular astigmatism, respectively, are analogous to keratometric spherical (equivalent) and astigmatic powers. The other Fourier components have no keratometric equivalent but have distinct clinical value. Decentration is a tilt of the cornea with respect to the videokeratoscope axis and irregular astigmatism is the sinusoidal variation in power that cannot be corrected with conventional lenses. CONCLUSION: The present paper demonstrates the application of Fourier series analysis to corneal topography data.

Excimer laser photorefractive keratectomy (PRK) procedures photoablate the central optical zone, potentially altering the corneal vertex normal and thus the corneal topography (CT) system reference axis. Anterior corneal surface coordinates (x, y, and z) were computer generated to simulate spherical and PRK-ablated corneal surfaces. Power maps were reconstructed by using surface tangents relative to various assumed CT reference axes, the original and displaced vertex normals. The simulation process eliminated focus, alignment, and surface-reconstruction errors. A simulated 5.00-D myopic PRK decentered 1 mm from the vertex produced a new corneal vertex 0.13 mm from the original position. Axial power-map generation by using this new reference axis produced a spherical keratectomy with astigmatic untreated periphery. This computer simulation demonstrates that reference axis changes are significant for even modest PRK decentration and can explain apparent steepening in untreated corneal areas. CT users should be aware that pre- and postoperative CT power maps may not be directly comparable.

A group of 20 subjects had fixation disparity curves plotted at three times in one day, and also had distance and near associated and dissociated heterophorias recorded. These measures were made in the morning, at midday and in the evening. Statistical analysis showed that there were no time-of-day effects on fixation disparity of heterophoria.