This check is pivotal, especially for those who wear spectacles. Familiar to most, it involves reading letters or numerals and discerning the direction of the opening in special rings (Landolt rings) of varying sizes on a projection surface. The optician assesses your ability to identify these elements effortlessly. Subsequently, a subjective refraction takes place, where different lenses with varying powers are inserted into a trial frame. You provide feedback on whether each lens improves or worsens your vision. The optician fine-tunes the lens for each eye, followed by a binocular test to assess eye interaction. Additional tests can identify associated heterophoria, correctable and sometimes treatable. In Part 1 of our complimentary online check, we simulate visual performance testing on-screen, offering an initial impression of your vision quality. This simulation doesn't replace your optician's tests but provides valuable insight. During eye exams, the refractive power needed to correct vision defects is determined without accommodation, capturing the eye's automatic adjustment to different distances.

Color blindness, more prevalent in men than women and affecting around 180 million people globally, is a genetic defect where certain sensory cells in the retina, particularly red, green, and blue cones, do not function correctly. The most common type is red/green blindness. Partial color blindness involves the absence or malfunctioning of some sensory cells, leading to impaired color vision. This can pose risks, such as red-weak or red-blind drivers struggling to distinguish red lights in fog, perceiving them as black. Total color blindness, or achromatopsia, is rare and results in the inability to perceive any color nuances. Diagnosis involves tests like pseudoisochromatic plates, the Farnsworth test, and Nagel's anomaloscope. Part 2 of our complimentary online check allows you to assess your color vision using color charts, offering insights into your perception abilities.

Astigmatism, a refractive error in the eye, occurs when the focal point is unevenly distributed along the meridians. Like other refractive errors, astigmatism can change gradually, particularly with age. Symptoms may include eyestrain, headaches, or difficulty driving at night. Fortunately, properly fitted glasses or contacts can correct astigmatism. In Part 3, you can assess your eyes for astigmatism using a symbol featuring differently oriented groups of black lines. These lines are designed to appear in varying shades of grey if astigmatism is present. Your task is to indicate whether you perceive the lines as differently sharp or black, a potential first sign of astigmatism.

While it may seem inconspicuous, the contrast vision test holds significant importance for comfortable and strain-free vision. Inability to distinguish contrast differences can lead to eye fatigue, a familiar experience when computer screens lack proper contrast settings or when reading in poor light. Assessing contrast vision becomes crucial for detecting changes in our vision, with alterations in contrast sensitivity potentially indicating conditions like glaucoma. Part 4 of our online screening check replicates a contrast vision test, offering an initial indication if your contrast vision could be improved. Your optician can delve deeper into this aspect during a detailed examination.