The clinical relevance of structural changes of the optic nerve head and retinal nerve fibre layer in glaucomatous optic neuropathy

BACKGROUND: Imaging is widely used to quantify glaucomatous structural changes. Although previous studies have examined the relationship between structure and function, measured using standard automated perimetry (SAP), the true relevance of structural changes remains poorly understood. AIM: The aim of this body of work was to explore the structure-function relationship and to ascertain the point at which structural changes become associated with impaired ability to perform vision-dependent tasks. PLAN OF RESEARCH: After critically appraising previously described structurefunction models, an investigation was conducted progressively evaluating the relationship between glaucomatous structural changes and 1) estimated loss of retinal ganglion cells (RGCs), 2) an objective measure of visual function (the pupil response), and 3) a vision-related task relevant to quality of life (driving). RESULTS: Localised RNFL defects visible on photographs, a common manifestation of glaucoma, were associated with large estimated RGC losses. However, problems were identified with the published method of RGC estimation. Asymmetric RNFL thinning was also found to be associated with asymmetry of the pupil response, and the magnitude of asymmetry required for a clinically detectable relative afferent pupillary defect (RAPD) was calculated. Finally, loss of RNFL was associated with worse ability to perform a simulated driving task, providing additional information to SAP alone. SIGNIFICANCE: Glaucomatous structural defects may be associated with significant functional impairment. Incorporating information from both structure and function may improve our ability to predict patients at risk of developing problems with vision-related tasks of daily living

Paediatric glaucoma in Scotland

Background The primary aim was to estimate the incidence of primary and secondary childhood glaucoma in Scotland over a 2-year period. The secondary aim was to gauge the confidence and experience of ophthalmologists in Scotland in managing these patients. Methods A 7 question electronic survey was distributed to all consultant members of the Scottish Paediatric Club and Scottish Glaucoma Club. Respondents were asked to report the number of cases and types of childhood glaucoma they had managed in the last 2 years. Respondents were also asked about experience and confidence in a range of glaucoma procedures, number of patients requiring referral to specialist centres and interest in the development of a centre of excellence in Scotland. Results The survey returned a 56% response rate, reporting 85 new cases of paediatric glaucoma in Scotland over the preceding 2 years. 11 (12.9%) had primary glaucoma and 74 (87.1%) had secondary glaucoma. The most common subtype of secondary glaucoma was uveitic glaucoma (n = 29). None of the respondents declared confidence or experience in trabeculotomy or goniotomy procedures. Eleven children required referral to a specialist unit outside Scotland. 85.7% of respondents felt Scotland would benefit from a specialist unit for paediatric glaucoma. Conclusions This survey reflects an appetite for a specialist service for paediatric glaucoma in Scotland. However, further consideration is needed to determine if there is sufficient patient load to maintain such a service.Publisher PDFPeer reviewe

Higher intraocular pressure is associated with slower axial growth in children with non-pathological high myopia

ObjectivesTo investigate the association between intraocular pressure (IOP) and axial elongation rate in highly myopic children from the ZOC-BHVI High Myopia Cohort Study.Methods162 eyes of 81 healthy children (baseline spherical equivalent: −6.25 D to −15.50 D) aged 7–12 years with non-pathological high myopia were studied over five biennial visits. The mean (SD) follow-up duration was 5.2 (3.3) years. A linear mixed-effects model (LMM) was used to assess the association between IOP (at time point t−1) and axial elongation rate (annual rate of change in AL from t−1 to t), controlling for a pre-defined set of covariates including sex, age, central corneal thickness, anterior chamber depth and lens thickness (at t−1). LMM was also used to assess the contemporaneous association between IOP and axial length (AL) at t, controlling for the same set of covariates (at t) as before.ResultsHigher IOP was associated with slower axial growth (β = −0.01, 95% CI −0.02 to −0.005, p = 0.001). There was a positive contemporaneous association between IOP and AL (β = 0.03, 95% CI 0.01–0.05, p = 0.004), but this association became progressively less positive with increasing age, as indicated by a negative interaction effect between IOP and age on AL (β = −0.01, 95% CI −0.01 to −0.003, p = 0.001).ConclusionsHigher IOP is associated with slower rather than faster axial growth in children with non-pathological high myopia, an association plausibly confounded by the increased influence of ocular compliance on IOP

Estimated Rates of Retinal Ganglion Cell Loss in Glaucomatous Eyes with and without Optic Disc Hemorrhages

Purpose: To evaluate whether optic disc hemorrhages are associated with faster rates of estimated retinal ganglion cell (RGC) loss in glaucoma.Methods: A longitudinal observational cohort study of 222 eyes of 122 patients with glaucoma recruited from the Diagnostic Innovations Glaucoma Study (DIGS) followed for an average of 3.74 +/- 0.85 years. All subjects had optical coherence tomography and standard automated perimetry during follow up. Optic disc hemorrhages were detected by masked evaluation of stereophotographs. Rates of change in estimated numbers of RGCs were determined using a previously described method. A random coefficients model was used to investigate the relationship between disc hemorrhages and rates of change in estimated RGC counts over time.Results: 19 eyes of 18 subjects had at least one disc hemorrhage during follow up. At baseline, average estimated RGC counts in eyes with and without disc hemorrhages were 677,994 cells and 682,021 cells, respectively (P = 0.929). Eyes with optic disc hemorrhages during follow-up had significantly faster rates of estimated RGC loss than eyes without disc hemorrhages (22,233 cells/year versus 10,704 cells/year, P = 0.020). the effect of disc hemorrhages on the rates of estimated RGC loss remained significant after adjusting for confounding variables.Conclusion: Eyes with disc hemorrhages showed faster rates of RGC loss compared to eyes without disc hemorrhages. These results provide further evidence that disc hemorrhages should be considered as an indicator of increased risk for faster neural loss in glaucoma.National Institutes of Health/National Eye InstituteResearch to Prevent Blindness (New York, N.Y.)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)AlconAllerganPfizerMerckSantenUniv Calif San Diego, Hamilton Glaucoma Ctr, San Diego, CA 92103 USAUniv Calif San Diego, Dept Ophthalmol, San Diego, CA 92103 USAUniversidade Federal de São Paulo, Dept Ophthalmol, São Paulo, BrazilUniv Edinburgh, Princess Alexandra Eye Pavil, Edinburgh, Midlothian, ScotlandUniv Edinburgh, Dept Ophthalmol, Edinburgh, Midlothian, ScotlandUniversidade Federal de São Paulo, Dept Ophthalmol, São Paulo, BrazilNational Institutes of Health/National Eye Institute: EY021818National Institutes of Health/National Eye Institute: EY11008National Institutes of Health/National Eye Institute: EY14267National Institutes of Health/National Eye Institute: EY019869National Institutes of Health/National Eye Institute: P30EY022589CAPES: 12309-13-3Web of Scienc

Novel linkage approach to join community-acquired and national data

BackgroundCommunity optometrists in Scotland have performed regular free-at-point-of-care eye examinations for all, for over 15 years. Eye examinations include retinal imaging but image storage is fragmented and they are not used for research. The Scottish Collaborative Optometry-Ophthalmology Network e-research project aimed to collect these images and create a repository linked to routinely collected healthcare data, supporting the development of pre-symptomatic diagnostic tools.MethodsAs the image record was usually separate from the patient record and contained minimal patient information, we developed an efficient matching algorithm using a combination of deterministic and probabilistic steps which minimised the risk of false positives, to facilitate national health record linkage. We visited two practices and assessed the data contained in their image device and Practice Management Systems. Practice activities were explored to understand the context of data collection processes. Iteratively, we tested a series of matching rules which captured a high proportion of true positive records compared to manual matches. The approach was validated by testing manual matching against automated steps in three further practices.ResultsA sequence of deterministic rules successfully matched 95% of records in the three test practices compared to manual matching. Adding two probabilistic rules to the algorithm successfully matched 99% of records.ConclusionsThe potential value of community-acquired retinal images can be harnessed only if they are linked to centrally-held healthcare care data. Despite the lack of interoperability between systems within optometry practices and inconsistent use of unique identifiers, data linkage is possible using robust, almost entirely automated processes