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Importance: Myopia (ie, nearsightedness) is becoming the most common eye disorder to cause blindness in younger persons in many parts of the world. Visual impairment due to myopia is associated with structural changes of the retina and the globe because of elongation of the eye axis. How axial length-a sum of the anterior chamber depth, lens thickness, and vitreous chamber depth-and myopia relate to the development of visual impairment over time is unknown., Objectives: To evaluate the association between axial length, spherical equivalent, and the risk of visual impairment and to make projections of visual impairment for regions with high prevalence rates., Design, Setting, and Participants: This cross-sectional study uses population-based data from the Rotterdam Study I (1990 to 1993), II (2000 to 2002), and III (2006 to 2008) and the Erasmus Rucphen Family Study (2002 to 2005) as well as case-control data from the Myopia Study (2010 to 2012) from the Netherlands. In total, 15 404 individuals with data on spherical equivalent and 9074 individuals with data on axial length were included in the study; right eyes were used for analyses. Data were analyzed from September 2014 to May 2016., Main Outcomes and Measures: Visual impairment and blindness (defined according to the World Health Organization criteria as a visual acuity less than 0.3) and predicted rates of visual impairment specifically for persons with myopia., Results: Of the 15 693 individuals included in this study, the mean (SD) age was 61.3 (11.4) years, and 8961 (57.1%) were female. Axial length ranged from 15.3 to 37.8 mm; 819 individuals had an axial length of 26 mm or greater. Spherical equivalent ranged from -25 to +14 diopters; 796 persons had high myopia (ie, a spherical equivalent of -6 diopters or less). The prevalence of visual impairment varied from 1.0% to 4.1% in the population-based studies, was 5.4% in the Myopia Study, and was 0.3% in controls. The prevalence of visual impairment rose with increasing axial length and spherical equivalent, with a cumulative incidence (SE) of visual impairment of 3.8% (1.3) for participants aged 75 years with an axial length of 24 to less than 26 mm and greater than 90% (8.1) with an axial length of 30 mm or greater. The cumulative risk (SE) of visual impairment was 5.7% (1.3) for participants aged 60 years and 39% (4.9) for those aged 75 years with a spherical equivalent of -6 diopters or less. Projections of these data suggest that visual impairment will increase 7- to 13-fold by 2055 in high-risk areas., Conclusions and Relevance: This study demonstrated that visual impairment is associated with axial length and spherical equivalent and may be unavoidable at the most extreme values in this population. Developing strategies to prevent the development of myopia and its complications could help to avoid an increase of visual impairment in the working-age population.

In the year 2004 there were an estimated 220,000-320,000 people in The Netherlands with visual impairment. In 150,000-220,000 (70%) of them the visual impairment is either curable or could have been prevented. Those most at risk are people with intellectual disabilities, elderly people in care institutions, elderly people in general and diabetics. 'Vision 2020 Netherlands', an initiative of the World Health Organization, was launched to eliminate avoidable visual impairment in the Netherlands by the year 2020 by means of awareness campaigns, implementation of screening programmes and by expanding eye care capacity through efficient cooperation between the professional groups involved in eye care.

Aim: To assess foveal cone photoreceptor function in patients with unexplained loss of central visual acuity., Methods: Testing of foveal cone photoreceptor function was performed using scanning laser densitometry, colour matching (Rayleigh equation), and pattern electroretinography (ERG). Standard tests included full field ERG, electrooculography, visual evoked potentials, static perimetry, and fluorescein angiography., Results: Decreased foveal cone photopigment density and abnormal pattern ERG were found in three patients. Results of colour matching were not unequivocal., Conclusion: Testing of foveal cone photoreceptor function using scanning laser densitometry may determine the location of pathological changes in certain patients with unexplained visual loss.

A 28-year-old man with multiple evanescent white dot syndrome (MEWDS) in the left eye was examined with a scanning laser densitometer. The first measurements were taken in the acute stage, and repeat examinations were performed during the process of recovery. Fundus pictures were obtained from a 20 degrees retinal field, in dark and light adapted stages. From these images visual pigment density maps were derived. In the acute stage of the disease, maps revealed small round areas of absent visual pigment, which did not always correspond with the visible white dots. The areas of absent visual pigment density were also larger than the white dots seen on funduscopic examination. Single spot densitometry at the fovea was also performed and showed no significant density difference of the foveal cones. Rod density difference measured at a locus 16 degrees in the temporal retina was much lower than normal with an increased time constant of rhodopsin regeneration. Ten weeks after the onset of the disease, no white dot lesions were visible on funduscopic examination. Rod density difference and regeneration time had become normal again, but with scanning laser densitometry the abnormal areas of no pigment were still faintly visible. It is concluded that these findings, completed with data of electroretinography, anomaloscopic testing, and perimetry, are in agreement with a metabolic disturbance at the level of the retinal pigment epithelium-photoreceptor complex.