We all communicate. Communication involves an action or characteristic of one individual that influences the behavior of another individual in a non-coercive way. One key way individuals communicate is through the use of eye signals. A signal is a display or act produced by a sender that influences the behavior of the receiver, wherein the signal and its response evolved in senders and receivers because, on average, senders and receivers benefit from the use of the signal.
Another key way individuals communicate is through the use of cues. A cue is a phenotypic variation in a sender that causes a reaction in a receiver that benefits the receiver even though the phenotypic variation in the sender has not evolved to cause that reaction.
When you look at your prescription for eyeglasses, you will see numbers listed under the headings of OS and OD. They are Latin abbreviations: OS (oculus sinister) means the left eye and OD (oculus dextrus) means the right eye. Occasionally, you will see a notation for OU, which means something involving both eyes.
In general, the further away from zero the number on your prescription, the worse your eyesight and the more vision correction (stronger prescription) you need. A “plus” (+) sign in front of the number means you are farsighted, and a “minus” (-) sign means you are nearsighted. These numbers represent diopters, the unit used to measure the correction, or focusing power, of the lens your eye requires. Diopter is often abbreviated “D.”
For example, if your prescription says -1.00, you have one diopter of nearsightedness. This is a fairly mild amount of nearsightedness. If you are -4.25, that means you have 4 and 1/4 diopters of nearsightedness. This is more nearsighted than -1.00 and requires stronger (thicker) lenses. Similarly, +1.00 would be a small amount of farsightedness, and +5 would be more.
For people who have astigmatism, there will be three numbers in your prescription. The general form for writing these numbers is S x C x Axis.
The S refers to the “spherical” portion of the prescription, which is the degree of nearsightedness or farsightedness discussed above.
The C refers to the “cylinder” or astigmatism and can be a negative or a positive number. It measures in diopters the degree of astigmatism that you have. The bigger this number, the more astigmatism you have. Astigmatism most often is caused by a cornea that is shaped more like a football than a basketball.
The Axis is a number anywhere between 0 and 180 degrees. It reveals the orientation of astigmatism. It is not enough to specify how much astigmatism there is; you have to know where the difference in curvature is taking place.
Here are two examples of what prescriptions for eyes with astigmatism could look like
-2.00 +1.50 x 180
+3.50 +3.00 x 45
The first prescription means that the person has 2 diopters of nearsightedness with 1.5 diopters of astigmatism and an axis of 180 degrees.
The second prescription means that the person has 3.5 diopters of farsightedness, 3 diopters of astigmatism, and an axis of 45 degrees.
Standard Practice of Eye Safeguards
Safeguard your vision – it’s never too late to change a routine or break a habit. Here are a few recommendations that will help you get your eye health and vision on track gradually.
Rest the eyes | Taking regular breaks after every 30-40 minutes of reading, writing, or playing the computer is recommended. Time spent on electronic devices such as tablets, mobile phones, or handheld devices should be reduced too.
It is recommended that children should engage with entertainment media for no more than 1 or 2 hours per day. Television or other entertainment media should be avoided for infants and children under age. A child’s brain develops rapidly during these first years, and young children learn best by interacting with people, not screens.
Protection against sun damage | Invest in sun protection accessories such as sunglasses with ultraviolet (UV) protection, or hats to shield your child from the sun’s damaging rays. For younger children, a hat or umbrella will be more ideal to avoid the risk of them poking their eyes with the sunglasses.
Increase time spent outdoors | Outdoor activities delay the development of myopia. Therefore, incorporating more outdoor activities with your child like swimming or cycling is beneficial. These outdoor activities promote physical fitness as well as improve hand-eye coordination for your child. However, do remember to avoid the heated periods of the day (typically from 11am to 4pm).
Intake of fruits, vegetables and fatty fish | Eating vegetables and fruits that are high in lutein and zeaxanthin have been found to protect the eyes from free radical damage. These nutrients can be found in foods such as kale, collard greens, spinach, brussels sprout, egg yolks, corn, avocado, pistachios, goji berries, orange peppers, kiwi, grapes, orange juice, and zucchini. Eating fatty fish like salmon, herring, and tuna is also beneficial to the development of the eyes.
Get regular eye exams | Your eye examiner can identify and treat eye problems early. It’s important to schedule yearly eye care appointments, so any developing issues can be cared for as early as possible. The exam should be conducted from children starting when they are newborns, during infancy (between six months to one year), and throughout their pre-school and school-going years.
Encourage healthy eye care habits | Maintain healthy eye care habits such as providing adequate lighting when your child is reading or playing. When reading, your child should be kept about 30-40cm away from the book, or about 50cm away from electronic devices. Getting at least eight hours of sleep each night is also important in preventing your child’s eyes from getting strained.
Wearing eye protection | If you have a job or activity where you could get an eye injury, always wear eye protection. This could include various sports, construction work, or factory work.
Exercising regularly | Making time to regularly exercise can help to prevent a variety of health issues throughout your life. These can include diabetes and high blood pressure, which can cause vision problems.
Avoid smoking | Not smoking can reduce your risk of developing diseases like cataracts and macular degeneration.
Blink, Blink, Blink | Another result of extensive device use is that your blink rate tends to drop when you stare at text on a screen. Not blinking often enough can lead to dry, irritated eyes. Apply the 20-20-20 rule: every 20 minutes look at an object 20 feet away for 20 seconds and don’t forget to blink!
Throw away old eye makeup | Such as mascara that is over four months old. Sharpen eyeliner pencils regularly and don’t put liner on the inside of your eyelid. If your eyes become irritated, stop using eye makeup until they heal.
Investigate “RED EYE” Warning Signs | This signal for a possible vision problem involves the red-eye displayed by children in their photographs. If a child is looking directly at the camera, ophthalmologists say the red should be equal—or appearing the same—in each eye. (Adults must keep in mind, however, that a child must be looking directly at the camera for these “red-eye” warnings to have any validity). If a child gets an unusual white reflection off the back of the eye or complete absence of the reflex in one eye consistently, that is a potential cause for concern.
The earlier an eye problem is detected, the earlier the appropriate treatment could be recommended for you and your child to prevent permanent visual impairment. In the event of a positive detection, intervention, including a prescription for glasses, patch therapy, medication or even surgery may be prescribed by the ophthalmologist to restore your and your child’s vision.