Riccardo Cheloni; Alexander G  Swystun; Mauro  Frisani; Christopher J  Davey

doi:10.5384/sjovs.v14i1.129

Authors

Riccardo Cheloni Bradford School of Optometry & Vision Science, University of Bradford https://orcid.org/0000-0002-6871-9498
Alexander G Swystun Bradford School of Optometry & Vision Science, University of Bradford, Bradford, UK https://orcid.org/0000-0003-1394-3027
Mauro Frisani University of Turin, Turin, IT; COMiB Research Centre in Optics and Optometry, University of Milano–Bicocca, Milan, IT https://orcid.org/0000-0002-5758-3353
Christopher J Davey Bradford School of Optometry & Vision Science, University of Bradford, Bradford, UK https://orcid.org/0000-0002-9050-379X

DOI:

https://doi.org/10.5384/sjovs.v14i1.129

Keywords:

Referral, routine eye examination, avoidable vision loss, refraction, asymptomatic patients, public health

Abstract

Italian optometrists refract patients and prescribe optical appliances. The routine optometric examination that is currently conducted in Italy, however, does not include a comprehensive ocular health assessment. Like many other countries, in Italy ophthalmologists are solely responsible for the diagnosis and treatment of ocular pathologies, yet, the care an optometrist provides must be done with the aim of promoting the general and ocular health of patients seen in practice. Such scope has to be pursued using a close collaboration with ophthalmologists, ultimately facilitating the earliest medical diagnosis and minimisation of visual impairment. Referral represents the basis of optometrist-ophthalmologist collaboration, yet, no guidance is available to Italian optometrists indicating when referral is warranted. The purpose of this study was to identify the circumstances deserving a referral in a routine Italian optometric examination in adults, ultimately constituting preliminary evidence-based indications of a referral model oriented to enhance the ocular and general health of patients. A literature review was conducted on Pubmed and the Cochrane Library, mainly targeting high quality secondary literature such as systematic reviews, meta-analysis and clinical guidelines. Several reasons for referral were identified. Further, while a wide range of anomalies of the visual system are likely to be discovered by the Italian optometric examination, up to 20% of patients could suffer an underlying condition undetected by the current assessment. This results in the need to refer seemingly healthy patients if they have not attended routine ophthalmological examinations within optimal time frames. In Italy, and countries with similar settings, the referral is an essential instrument that optometrists must largely use to ensure early diagnosis of ocular conditions by ophthalmologists and minimisation of avoidable visual impairment.

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References

Alexander, R. L., Miller, N. A., Cotch, M. F., & Janiszewski, R. (2008). Factors that influence the receipt of eye care. American Journal of Health Behavior, 32(5), 547-556. https://doi.org/10.5555/ajhb.2008.32.5.547

American Optometric Association. (2015). Comprehensive Adult Eye and Vision Examination Guide Line. Retrieved June 2020 from https://www.aoa.org/optometrists/tools-and-resources/evidence-based-optometry/evidence-based-clinical-practice-guidlines/evidence-based-clinical-practice-guideline-adult-eye-and-vision-examination-

American Optometric Association. (2017). Comprehensive Pediatric Eye and Vision Examination Guide Line. Retrieved June 2020 from https://www.aoa.org/optometrists/tools-and-resources/evidence-based-optometry/evidence-based-clinical-practice-guidlines/evidence-based-clinical-practice-guideline-comprehensive-pediatric-eye-and-vision-examination

Andersen, G. J. (2012). Aging and vision: changes in function and performance from optics to perception. Wiley Interdisciplinary Reviews Cognitive Science, 3(3), 403-410. https://doi.org/10.1002/wcs.1167

Bagolini, B. (1974). Sensory anomalies in strabismus. The British journal of ophthalmology, 58(3), 313-318. https://doi.org/10.1136/bjo.58.3.313

Baker, H., Ratnarajan, G., Harper, R. A., Edgar, D. F., & Lawrenson, J. G. (2016). Effectiveness of UK optometric enhanced eye care services: a realist review of the literature. Ophthalmic and Physiological Optics, 36(5), 545-557. https://doi.org/10.1111/opo.12312

Baker, R. S., Bazargan, M., Bazargan-Hejazi, S., & Calderon, J. L. (2005). Access to vision care in an urban low-income multiethnic population. Ophthalmic epidemiology, 12(1), 1-12. https://doi.org/10.1080/09286580590921330

Barrett, C., O'Brien, C., & Loughman, J. (2018). Glaucoma referral refinement in Ireland: managing the sensitivity-specificity paradox in optometric practice. Ophthalmic and Physiological Optics, 38(4), 400-410. https://doi.org/10.1111/opo.12446

Bourne, R. R., Jonas, J. B., Flaxman, S. R., Keeffe, J., Leasher, J., Naidoo, K., Parodi, M. B., Pesudovs, K., Price, H., White, R. A., Wong, T. Y., Resnikoff, S., & Taylor, H. R. (2014). Prevalence and causes of vision loss in high-income countries and in Eastern and Central Europe: 1990-2010. British Journal of Ophthalmology, 98(5), 629-638. https://doi.org/10.1136/bjophthalmol-2013-304033

Bourne, R. R. A., Jonas, J. B., Bron, A. M., Cicinelli, M. V., Das, A., Flaxman, S. R., Friedman, D. S., Keeffe, J. E., Kempen, J. H., Leasher, J., Limburg, H., Naidoo, K., Pesudovs, K., Peto, T., Saadine, J., Silvester, A. J., Tahhan, N., Taylor, H. R., Varma, R., Wong, T. Y., & Resnikoff, S. (2018). Prevalence and causes of vision loss in high-income countries and in Eastern and Central Europe in 2015: magnitude, temporal trends and projections. British Journal of Ophthalmology. https://doi.org/10.1136/bjophthalmol-2017-311258

Bowling, B., Chen, S. D. M., & Salmon, J. F. (2005). Outcomes of referrals by community optometrists to a hospital glaucoma service. The British journal of ophthalmology, 89(9), 1102-1104. https://doi.org/10.1136/bjo.2004.064378

Cacho-Martinez, P., Canto-Cerdan, M., Carbonell-Bonete, S., & Garcia-Munoz, A. (2015). Characterization of Visual Symptomatology Associated with Refractive, Accommodative, and Binocular Anomalies. Journal of Ophthalmology, 2015, 895803. https://doi.org/10.1155/2015/895803

Cacho-Martinez, P., Garcia-Munoz, A., & Ruiz-Cantero, M. T. (2014). Is there any evidence for the validity of diagnostic criteria used for accommodative and nonstrabismic binocular dysfunctions? Journal of Optometry, 7(1), 2-21. https://doi.org/10.1016/j.optom.2013.01.004

Cacho-Martínez, P., García-Muñoz, Á., & Ruiz-Cantero, M. T. (2010). Do we really know the prevalence of accomodative and nonstrabismic binocular dysfunctions? Journal of Optometry, 3(4), 185-197. https://doi.org/10.1016/s1888-4296(10)70028-5

Campbell, P., Redmond, T., Agarwal, R., Marshall, L. R., & Evans, B. J. (2015). Repeatability and comparison of clinical techniques for anterior chamber angle assessment. Ophthalmic and Physiological Optics, 35(2), 170-178. https://doi.org/10.1111/opo.12200

Chakravarthy, U., Wong, T. Y., Fletcher, A., Piault, E., Evans, C., Zlateva, G., Buggage, R., Pleil, A., & Mitchell, P. (2010). Clinical risk factors for age-related macular degeneration: a systematic review and meta-analysis. BMC Ophthalmology, 10, 31. https://doi.org/10.1186/1471-2415-10-31

Cocce, K. J., Stinnett, S. S., Luhmann, U. F. O., Vajzovic, L., Horne, A., Schuman, S. G., Toth, C. A., Cousins, S. W., & Lad, E. M. (2018). Visual Function Metrics in Early and Intermediate Dry Age-related Macular Degeneration for Use as Clinical Trial Endpoints. American journal of ophthalmology, 189, 127-138. https://doi.org/10.1016/j.ajo.2018.02.012

Colijn, J. M., Buitendijk, G. H. S., Prokofyeva, E., Alves, D., Cachulo, M. L., Khawaja, A. P., Cougnard-Gregoire, A., Merle, B. M. J., Korb, C., Erke, M. G., Bron, A., Anastasopoulos, E., Meester-Smoor, M. A., Segato, T., Piermarocchi, S., de Jong, P., Vingerling, J. R., Topouzis, F., Creuzot-Garcher, C., Bertelsen, G., Pfeiffer, N., Fletcher, A. E., Foster, P. J., Silva, R., Korobelnik, J. F., Delcourt, C., & Klaver, C. C. W. (2017). Prevalence of Age-Related Macular Degeneration in Europe: The Past and the Future. Ophthalmology, 124(12), 1753-1763. https://doi.org/10.1016/j.ophtha.2017.05.035

College of Optometrists. (2020). The routine eye examination. Retrieved February 2021 from https://guidance.college-optometrists.org/guidance-contents/knowledge-skills-and-performance-domain/the-routine-eye-examination/

Consorzio per la Ricerca Economica Applicata in Sanità. (2017). “Osservatorio sui tempi di attesa e sui costi delle prestazioni sanitarie nei Sistemi Sanitarie Regionali”. Retrieved May 2018 from http://www.quotidianosanita.it/allegati/allegato2112108.pdf

Cook, J. A., Botello, A. P., Elders, A., Fathi Ali, A., Azuara-Blanco, A., Fraser, C., McCormack, K., & Margaret Burr, J. (2012). Systematic review of the agreement of tonometers with Goldmann applanation tonometry. Ophthalmology, 119(8), 1552-1557. https://doi.org/10.1016/j.ophtha.2012.02.030

Craig, J. P., Nichols, K. K., Akpek, E. K., Caffery, B., Dua, H. S., Joo, C.-K., Liu, Z., Nelson, J. D., Nichols, J. J., & Tsubota, K. (2017). TFOS DEWS II definition and classification report. The ocular surface, 15(3), 276-283.

Davey, C. J., Green, C., & Elliott, D. B. (2011). Assessment of referrals to the hospital eye service by optometrists and GPs in Bradford and Airedale. Ophthalmic and Physiological Optics, 31(1), 23-28. https://doi.org/10.1111/j.1475-1313.2010.00797.x

Davey, C. J., Scally, A. J., Green, C., Mitchell, E. S., & Elliott, D. B. (2016). Factors influencing accuracy of referral and the likelihood of false positive referral by optometrists in Bradford, United Kingdom. Journal of Optometry, 9(3), 158-165. https://doi.org/10.1016/j.optom.2015.10.007

Diez Ajenjo, M. A., Garcia Domene, M. C., & Peris Martinez, C. (2015). Refractive changes in nuclear, cortical and posterior subcapsular cataracts. effect of the type and grade. Journal of Optometry, 8(2), 86-92. https://doi.org/10.1016/j.optom.2014.07.006

Doyle, L. A., McCullough, S. J., & Saunders, K. J. (2019). Cycloplegia and spectacle prescribing in children: attitudes of UK optometrists. Ophthalmic and Physiological Optics, 39(3), 148-161. https://doi.org/https://doi.org/10.1111/opo.12612

Durr, N. J., Dave, S. R., Lage, E., Marcos, S., Thorn, F., & Lim, D. (2014). From unseen to seen: tackling the global burden of uncorrected refractive errors. Annual Review of Biomedical Engineering, 16, 131-153. https://doi.org/10.1146/annurev-bioeng-071813-105216

ECOO European Council of Optometry and Optics. (2020). ECOO Blue Book 2020. Retrieved February 2021 from https://www.ecoo.info/2020/10/ecoo-blue-book-2020/

Elam, A. R., & Lee, P. P. (2013). High-Risk Populations for Vision Loss and Eye Care Underutilization: A Review of the Literature and Ideas on Moving Forward. Survey of Ophthalmology, 58(4), 348-358. https://doi.org/10.1016/j.survophthal.2012.07.005

Elliott. (2013). Clinical Procedures in Primary Eye Care E-Book. Elsevier Health Sciences.

Elliott, D. B., Yang, K. C., & Whitaker, D. (1995). Visual acuity changes throughout adulthood in normal, healthy eyes: seeing beyond 6/6. Optometry and Vision Science, 72(3), 186-191. https://doi.org/10.1097/00006324-199503000-00006

Evans, B. J. W. (2007). “Pickwell's binocular vision anomalies: investigation and treatment”. (E. H. Sciences, Ed.).

Faes, L., Bodmer, N. S., Bachmann, L. M., Thiel, M. A., & Schmid, M. K. (2014). Diagnostic accuracy of the Amsler grid and the preferential hyperacuity perimetry in the screening of patients with age-related macular degeneration: systematic review and meta-analysis. Eye (Lond), 28(7), 788-796. https://doi.org/10.1038/eye.2014.104

Feder, R. S., Olsen, T. W., Prum, B. E., Jr., Summers, C. G., Olson, R. J., Williams, R. D., & Musch, D. C. (2016). Comprehensive Adult Medical Eye Evaluation Preferred Practice Pattern((R)) Guidelines. Ophthalmology, 123(1), P209-236. https://doi.org/10.1016/j.ophtha.2015.10.047

Ferguson, L. (2004). External validity, generalizability, and knowledge utilization. Journal of Nursing Scholarship, 36(1), 16-22. https://doi.org/10.1111/j.1547-5069.2004.04006.x

Flaxman, S. R., Bourne, R. R. A., Jonas, J. B., Kempen, J. H., Stevens, G. A., Tahhan, N., Wong, T. Y., & Taylor, H. R. (2017). Global causes of blindness and distance vision impairment 1990-2020: a systematic review and meta-analysis. The Lancet Global Health, 5(12), e1221-e1234. https://doi.org/10.1016/S2214-109X(17)30393-5

Foot, B., & MacEwen, C. (2017). Surveillance of sight loss due to delay in ophthalmic treatment or review: Frequency, cause and outcome. Eye (Basingstoke), 31(5), 771-775. https://doi.org/10.1038/eye.2017.1

Fotouhi, A., Morgan, I. G., Iribarren, R., Khabazkhoob, M., & Hashemi, H. (2012). Validity of noncycloplegic refraction in the assessment of refractive errors: the Tehran Eye Study. Acta Ophthalmologica, 90(4), 380-386. https://doi.org/10.1111/j.1755-3768.2010.01983.x

Frick, K. D., & Foster, A. (2003). The magnitude and cost of global blindness: an increasing problem that can be alleviated. American journal of ophthalmology, 135(4), 471-476. https://doi.org/10.1016/s0002-9394(02)02110-4

Garcia-Munoz, A., Carbonell-Bonete, S., & Cacho-Martinez, P. (2014). Symptomatology associated with accommodative and binocular vision anomalies. Journal of Optometry, 7(4), 178-192. https://doi.org/10.1016/j.optom.2014.06.005

George, P. P., Yun, O. C. S., Siow, K., Saxena, N., Heng, B. H., Car, J., & Lockwood, C. (2019). Is there scope for expanding the optometrist's scope of practice in Singapore? – A survey of optometrists, opticians in Singapore [Article]. Contact Lens and Anterior Eye, 42(3), 258-264. https://doi.org/10.1016/j.clae.2019.02.008

Gerstenblith, A., & Rabinowitz, M. (2012). “The Wills eye manual: office and emergency room diagnosis and treatment of eye disease”. (L. W. Wilkins, Ed.).

Goebels, S., Kasmann-Kellner, B., Eppig, T., Seitz, B., & Langenbucher, A. (2015). Can retinoscopy keep up in keratoconus diagnosis? Cont Lens Anterior Eye, 38(4), 234-239. https://doi.org/10.1016/j.clae.2015.01.015

Goss, D. A., & Grosvenor, T. (1996). Reliability of refraction--a literature review. Journal of the American Optometric Association, 67(10), 619-630.

Greenhalgh, T., Thorne, S., & Malterud, K. (2018). Time to challenge the spurious hierarchy of systematic over narrative reviews? European journal of clinical investigation, 48(6), e12931-e12931. https://doi.org/10.1111/eci.12931

Guzowski, M., Wang, J. J., Rochtchina, E., Rose, K. A., & Mitchell, P. (2003). Five-year refractive changes in an older population: the Blue Mountains Eye Study. Ophthalmology, 110(7), 1364-1370. https://doi.org/10.1016/s0161-6420(03)00465-2

Henson, D. B., Spencer, A. F., Harper, R., & Cadman, E. J. (2003). Community refinement of glaucoma referrals. Eye (London, England), 17(1), 21-26. https://doi.org/10.1038/sj.eye.6700261

Huntjens, B., Charman, W. N., Workman, H., Hosking, S. L., & O'Donnell, C. (2012). Short-term stability in refractive status despite large fluctuations in glucose levels in diabetes mellitus type 1 and 2. PLoS One, 7(12), e52947. https://doi.org/10.1371/journal.pone.0052947

Hyman, L. (2007). Myopic and hyperopic refractive error in adults: an overview. Ophthalmic Epidemiol, 14(4), 192-197. https://doi.org/10.1080/09286580701535517

Irving, E. L., Harris, J. D., Machan, C. M., Robinson, B. E., Hrynchak, P. K., Leat, S. J., & Lillakas, L. (2016). Value of Routine Eye Examinations in Asymptomatic Patients. Optometry and Vision Science, 93(7), 660-666. https://doi.org/10.1097/opx.0000000000000863

Kapetanakis, V. V., Chan, M. P., Foster, P. J., Cook, D. G., Owen, C. G., & Rudnicka, A. R. (2016). Global variations and time trends in the prevalence of primary open angle glaucoma (POAG): a systematic review and meta-analysis. British Journal of Ophthalmology, 100(1), 86-93. https://doi.org/10.1136/bjophthalmol-2015-307223

Kassebaum NJ, Arora M, Barber RM, Bhutta ZA, Brown J, Carter A, Casey DC, Charlson FJ, & Coates MM. (2016). Global, regional, and national disability-adjusted life-years (DALYs) for 315 diseases and injuries and healthy life expectancy (HALE), 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet, 388(10053), 1603-1658. https://doi.org/10.1016/s0140-6736(16)31460-x

Kempen, G. I., & Zijlstra, G. A. (2014). Clinically relevant symptoms of anxiety and depression in low-vision community-living older adults. The American Journal of Geriatric Psychiatry, 22(3), 309-313. https://doi.org/10.1016/j.jagp.2012.08.007

Kiely, P., & Chappell, R. (2015). A Global Competency Based Model of Scope of Practice in Optometry. World Council of Optometry.

Klein, B. E., Lee, K. E., & Klein, R. (2011). Refraction in adults with diabetes. Arch Ophthalmol, 129(1), 56-62. https://doi.org/10.1001/archophthalmol.2010.322

Kosmorsky, G. S., & Diskin, D. (1991). Examination of the pupil. In The Basics of Neuro-ophthalmology. Philadelphia: Mosby.

Kukull, W. A., & Ganguli, M. (2012). Generalizability: the trees, the forest, and the low-hanging fruit. Neurology, 78(23), 1886-1891. https://doi.org/10.1212/WNL.0b013e318258f812

Lamoureux, E. L., Fenwick, E., Moore, K., Klaic, M., Borschmann, K., & Hill, K. (2009). Impact of the severity of distance and near-vision impairment on depression and vision-specific quality of life in older people living in residential care. Investigative Ophthalmology & Visual Science, 50(9), 4103-4109. https://doi.org/10.1167/iovs.08-3294

Laughton, D. S., Sheppard, A. L., & Davies, L. N. (2018). Refraction during incipient presbyopia: The Aston Longitudinal Assessment of Presbyopia (ALAP) study. Journal of Optometry, 11(1), 49-56. https://doi.org/10.1016/j.optom.2017.02.001

Leung, T. W., Lam, A. K., Deng, L., & Kee, C. S. (2012). Characteristics of astigmatism as a function of age in a Hong Kong clinical population. Optometry and Vision Science, 89(7), 984-992. https://doi.org/10.1097/OPX.0b013e31825da156

Li, J. Q., Welchowski, T., Schmid, M., Letow, J., Wolpers, C., Pascual-Camps, I., Holz, F. G., & Finger, R. P. (2020). Prevalence, incidence and future projection of diabetic eye disease in Europe: a systematic review and meta-analysis. European Journal of Epidemiology, 35(1), 11-23. https://doi.org/10.1007/s10654-019-00560-z

Livi, S., Zeri, F., & Baroni, R. (2017). Health beliefs affect the correct replacement of daily disposable contact lenses: Predicting compliance with the Health Belief Model and the Theory of Planned Behaviour. Contact lens & anterior eye : the journal of the British Contact Lens Association, 40(1), 25-32. https://doi.org/10.1016/j.clae.2016.09.003

Martinez-Roda, J. A., Vilaseca, M., Ondategui, J. C., Aguirre, M., & Pujol, J. (2016). Effects of aging on optical quality and visual function. Clinical and Experimental Optometry, 99(6), 518-525. https://doi.org/10.1111/cxo.12369

Martinez-Thompson, J. M., Diehl, N. N., Holmes, J. M., & Mohney, B. G. (2014). Incidence, types, and lifetime risk of adult-onset strabismus. Ophthalmology, 121(4), 877-882. https://doi.org/10.1016/j.ophtha.2013.10.030

McGraw, P. V., Winn, B., Gray, L. S., & Elliott, D. B. (2000). Improving the reliability of visual acuity measures in young children. Ophthalmic and Physiological Optics, 20(3), 173-184. https://doi.org/ https://doi.org/10.1046/j.1475-1313.2000.00497.x

McKendrick, A. M., & Brennan, N. A. (1995). Clinical evaluation of refractive techniques. Journal of the American Optometric Association, 66(12), 758-765.

McMonnies, C. W. (2017). Glaucoma history and risk factors. Journal of optometry, 10(2), 71-78. https://doi.org/10.1016/j.optom.2016.02.003

Mets, M. B., Rich, W. L., 3rd, Lee, P., Schuman, J. S., Wilson, D., Chew, E., & Buckley, E. (2012). The ophthalmic practice of the future. Archives of ophthalmology, 130(9), 1195-1198. https://doi.org/10.1001/archophthalmol.2012.1000

Michaud, L., & Forcier, P. (2014). Prevalence of asymptomatic ocular conditions in subjects with refractive-based symptoms. Journal of optometry, 7(3), 153-160. https://doi.org/10.1016/j.optom.2013.08.003

Mutti, D. O., & Zadnik, K. (2000). Age-related decreases in the prevalence of myopia: longitudinal change or cohort effect? Investigative ophthalmology & visual science, 41(8), 2103-2107.

Naroo, S. A., & Grit, F. (2009). Optometry and optics in Europe. Contact lens & anterior eye, 32(3), 101-102. https://doi.org/10.1016/j.clae.2009.04.002

National Institute for Health and Clinical Excellence NICE. (2017). Glaucoma: diagnosis and management, NICE guideline. Retrieved April 2018 from https://www.nice.org.uk/guidance/ng81/resources/glaucoma-diagnosis-and-management-pdf-1837689655237

Nelson, L. B., & Maumenee, I. H. (1982). Ectopia lentis. Survey of ophthalmology, 27(3), 143-160. https://doi.org/10.1016/0039-6257(82)90069-8

Owsley, C. (2016). Vision and Aging. Annu Rev Vis Sci, 2, 255-271. https://doi.org/10.1146/annurev-vision-111815-114550

Patel, S. V., Holmes, J. M., Hodge, D. O., & Burke, J. P. (2005). Diabetes and hypertension in isolated sixth nerve palsy: a population-based study. Ophthalmology, 112(5), 760-763. https://doi.org/10.1016/j.ophtha.2004.11.057

Patino, C. M., McKean-Cowdin, R., Azen, S. P., Allison, J. C., Choudhury, F., & Varma, R. (2010). Central and peripheral visual impairment and the risk of falls and falls with injury. Ophthalmology, 117(2), 199-206.e191. https://doi.org/10.1016/j.ophtha.2009.06.063

Pesudovs, K., & Elliott, D. B. (2003). Refractive error changes in cortical, nuclear, and posterior subcapsular cataracts. The British Journal of Ophthalmology, 87(8), 964-967. https://doi.org/10.1136/bjo.87.8.964

Peters, D., Bengtsson, B., & Heijl, A. (2014). Factors associated with lifetime risk of open-angle glaucoma blindness. Acta ophthalmologica, 92(5), 421-425. https://doi.org/10.1111/aos.12203

Picone, G., Brown, D., Sloan, F., & Lee, P. (2004). Do routine eye exams improve vision? International journal of health care finance and economics, 4(1), 43-63. https://doi.org/10.1023/b:ihfe.0000019262.27436.3d

Prum, B. E., Jr., Rosenberg, L. F., Gedde, S. J., Mansberger, S. L., Stein, J. D., Moroi, S. E., Herndon, L. W., Jr., Lim, M. C., & Williams, R. D. (2016). Primary Open-Angle Glaucoma Preferred Practice Pattern((R)) Guidelines. Ophthalmology, 123(1), P41-p111. https://doi.org/10.1016/j.ophtha.2015.10.053

Raasch, T. W., Schechtman, K. B., Davis, L. J., & Zadnik, K. (2001). Repeatability of subjective refraction in myopic and keratoconic subjects: results of vector analysis. Ophthalmic & physiological optics, 21(5), 376-383.

Ratnarajan, G., Newsom, W., Vernon, S. A., Fenerty, C., Henson, D., Spencer, F., Wang, Y., Harper, R., McNaught, A., Collins, L., Parker, M., Lawrenson, J., Hudson, R., Khaw, P. T., Wormald, R., Garway-Heath, D., & Bourne, R. (2013). The effectiveness of schemes that refine referrals between primary and secondary care--the UK experience with glaucoma referrals: the Health Innovation & Education Cluster (HIEC) Glaucoma Pathways Project. BMJ open, 3(7), e002715. https://doi.org/10.1136/bmjopen-2013-002715

Robinson, B. E. (2003). Prevalence of asymptomatic eye disease. Canadian Journal Optometry, 65, 175–180.

Robinson, B. E., Mairs, K., Glenny, C., & Stolee, P. (2012). An Evidence-Based Guideline for the Frequency of Optometric Eye Examinations. Primary Health Care 2:121. https://doi.org/10.4172/2167-1079.1000121

Sabanayagam, C., Banu, R., Chee, M. L., Lee, R., Wang, Y. X., Tan, G., Jonas, J. B., Lamoureux, E. L., Cheng, C.-Y., Klein, B. E. K., Mitchell, P., Klein, R., Cheung, C. M. G., & Wong, T. Y. (2019). Incidence and progression of diabetic retinopathy: a systematic review. The lancet. Diabetes & endocrinology, 7(2), 140-149. https://doi.org/10.1016/S2213-8587(18)30128-1

Sanfilippo, P. G., Chu, B. S., Bigault, O., Kearns, L. S., Boon, M. Y., Young, T. L., Hammond, C. J., Hewitt, A. W., & Mackey, D. A. (2014). What is the appropriate age cut-off for cycloplegia in refraction? Acta Ophthalmologica, 92(6), e458-462. https://doi.org/10.1111/aos.12388

Sanfilippo, P. G., Yazar, S., Kearns, L., Sherwin, J. C., Hewitt, A. W., & Mackey, D. A. (2015). Distribution of astigmatism as a function of age in an Australian population. Acta Ophthalmologica, 93(5), e377-385. https://doi.org/10.1111/aos.12644

Scanlon, P. H., Foy, C., & Chen, F. K. (2008). Visual acuity measurement and ocular co-morbidity in diabetic retinopathy screening. British Journal of Ophthalmology, 92(6), 775-778. https://doi.org/10.1136/bjo.2007.128561

Schuster, A. K., Pfeiffer, N., Schulz, A., Hoehn, R., Ponto, K. A., Wild, P. S., Blettner, M., Beutel, M. E., Lackner, K. J., Munzel, T., & Mirshahi, A. (2018). Refractive, corneal, and ocular residual astigmatism: distribution in a German population and age dependency-the Gutenberg Health Study. Graefe's archive for clinical and experimental ophthalmology, 256(2), 445-446. https://doi.org/10.1007/s00417-017-3822-7

Schwartz, L. (2002). Is there an advocate in the house? The role of health care professionals in patient advocacy. Journal of medical ethics, 28(1), 37-40. https://doi.org/10.1136/jme.28.1.37

Scilley, K., Jackson, G. R., Cideciyan, A. V., Maguire, M. G., Jacobson, S. G., & Owsley, C. (2002). Early age-related maculopathy and self-reported visual difficulty in daily life. Ophthalmology, 109(7), 1235-1242. https://doi.org/10.1016/s0161-6420(02)01060-6

Scully, N. D., Chu, L., Siriwardena, D., Wormald, R., & Kotecha, A. (2009). The quality of optometrists' referral letters for glaucoma. Ophthalmic & physiological optics, 29(1), 26-31. https://doi.org/10.1111/j.1475-1313.2008.00600.x

Senra, H., Barbosa, F., Ferreira, P., Vieira, C. R., Perrin, P. B., Rogers, H., Rivera, D., & Leal, I. (2015). Psychologic adjustment to irreversible vision loss in adults: a systematic review. Ophthalmology, 122(4), 851-861. https://doi.org/10.1016/j.ophtha.2014.10.022

Shah, R., & Wormald, R. P. (2011). Glaucoma. BMJ clinical evidence, 2011.

Simunovic, M. P. (2016). Acquired color vision deficiency. Survey of Ophthalmology, 61(2), 132-155. https://doi.org/10.1016/j.survophthal.2015.11.004

Taylor, H. R., Vu, H. T., McCarty, C. A., & Keeffe, J. E. (2004). The need for routine eye examinations. Investigative ophthalmology & visual science, 45(8), 2539-2542. https://doi.org/10.1167/iovs.03-1198

Ting, D. S., Cheung, G. C., & Wong, T. Y. (2016). Diabetic retinopathy: global prevalence, major risk factors, screening practices and public health challenges: a review. Clinical & experimental ophthalmology, 44(4), 260-277. https://doi.org/10.1111/ceo.12696

United Nations. (2017). World Population Prospects: The 2017 Revision, Data Booklet. Department of Economic and Social Affairs - Population Division. Retrieved May 2018 from https://esa.un.org/unpd/wpp/Publications/

Van Herick, W., Shaffer, R. N., & Schwartz, A. (1969). Estimation of width of angle of anterior chamber. Incidence and significance of the narrow angle. American journal of ophthalmology, 68(4), 626-629. https://doi.org/10.1016/0002-9394(69)91241-0

Vitali, C., Moutsopoulos, H. M., & Bombardieri, S. (1994). The European Community Study Group on diagnostic criteria for Sjögren's syndrome. Sensitivity and specificity of tests for ocular and oral involvement in Sjögren's syndrome. Annals of the rheumatic diseases, 53(10), 637-647. https://doi.org/10.1136/ard.53.10.637

Wang, F., Ford, D., Tielsch, J. M., Quigley, H. A., & Whelton, P. K. (1994). Undetected eye disease in a primary care clinic population. Archives of internal medicine, 154(16), 1821-1828.

Weinreb, R. N., Leung, C. K., Crowston, J. G., Medeiros, F. A., Friedman, D. S., Wiggs, J. L., & Martin, K. R. (2016). Primary open-angle glaucoma. Nature reviews, 2, 16067. https://doi.org/10.1038/nrdp.2016.67

Weiss, J. S., Møller, H. U., Aldave, A. J., Seitz, B., Bredrup, C., Kivelä, T., Munier, F. L., Rapuano, C. J., Nischal, K. K., Kim, E. K., Sutphin, J., Busin, M., Labbé, A., Kenyon, K. R., Kinoshita, S., & Lisch, W. (2015). IC3D classification of corneal dystrophies--edition 2. Cornea, 34(2), 117-159. https://doi.org/10.1097/ico.0000000000000307

Williams, K. M., Verhoeven, V. J., Cumberland, P., Bertelsen, G., Wolfram, C., Buitendijk, G. H., Hofman, A., van Duijn, C. M., Vingerling, J. R., Kuijpers, R. W., Hohn, R., Mirshahi, A., Khawaja, A. P., Luben, R. N., Erke, M. G., von Hanno, T., Mahroo, O., Hogg, R., Gieger, C., Cougnard-Gregoire, A., Anastasopoulos, E., Bron, A., Dartigues, J. F., Korobelnik, J. F., Creuzot-Garcher, C., Topouzis, F., Delcourt, C., Rahi, J., Meitinger, T., Fletcher, A., Foster, P. J., Pfeiffer, N., Klaver, C. C., & Hammond, C. J. (2015). Prevalence of refractive error in Europe: the European Eye Epidemiology (E(3)) Consortium. European journal of epidemiology, 30(4), 305-315. https://doi.org/10.1007/s10654-015-0010-0

Wolffsohn, J. S., Bhogal, G., & Shah, S. (2011). Effect of uncorrected astigmatism on vision. Journal of cataract and refractive surgery, 37(3), 454-460. https://doi.org/10.1016/j.jcrs.2010.09.022

Yau, J. W., Rogers, S. L., Kawasaki, R., Lamoureux, E. L., Kowalski, J. W., Bek, T., Chen, S. J., Dekker, J. M., Fletcher, A., Grauslund, J., Haffner, S., Hamman, R. F., Ikram, M. K., Kayama, T., Klein, B. E., Klein, R., Krishnaiah, S., Mayurasakorn, K., O'Hare, J. P., Orchard, T. J., Porta, M., Rema, M., Roy, M. S., Sharma, T., Shaw, J., Taylor, H., Tielsch, J. M., Varma, R., Wang, J. J., Wang, N., West, S., Xu, L., Yasuda, M., Zhang, X., Mitchell, P., & Wong, T. Y. (2012). Global prevalence and major risk factors of diabetic retinopathy. Diabetes Care, 35(3), 556-564. https://doi.org/10.2337/dc11-1909

Zadnik, K., Mutti, D. O., & Adams, A. J. (1992). The repeatability of measurement of the ocular components. Investigative ophthalmology & visual science, 33(7), 2325-2333.