Dr Ben Wild
Overview |
Prescription eye glasses are designed to help the eyes focus light on the retina (the posterior surface of the inside of the eye that detects light). If the eyes are perfectly focused together, there is no need for prescription eye glasses. Non-prescription glasses such as non-prescription blue blocking glasses or non-prescription sunglasses do not provide any focusing power.
Example |
1) OD refers to Oculus Dexter or right eye, OS refers to Oculus Sinister or left eye
2) The sphere, on a superficial level, describes whether someone is nearsighted (trouble seeing distant objects without glasses) or farsighted (someone who strains to see up close). Minus (-) means nearsighted, plus (+) means farsighted. The number behind the (-) or (+) indicates severity. Plano (0) to -3.00 is considered mild nearsightedness, -3.00 to -6.00 is considered moderate and over -6.00 is considered high. (0) to +1.50 is considered mild farsightedness, +1.50 to +3.50 is considered moderate, and over +3.50 is considered high.
3) Cylinder refers to how much astigmatism (eye is in the shape of a cylinder instead of a sphere) is being corrected by the glasses. Optometrists always use the minus (-) form and ophthalmologists often use (+) form. Either way, the number behind the (-) or (+) describes the severity of astigmatism. (0) to -1.25 is considered mild, -1.25 to -2.25 is considered moderate and over -2.25 is considered high.
4) The axis refers to the direction of the cylinder. When holding a cylinder, it could be at 0 (180 would be the same) degrees or could be turned to any angle from 0 to 179 degrees.
5) Add, or additional, power refers to how much power on top of the distance prescription is needed to help with near vision. This usually only applies in cases of accommodative dysfunction or presbyopia (both conditions describing the inability to change focus from far to near)
6) Prism is a rare finding in a prescription. Prisms bend light. Changing the direction of light can help alleviate eye strain in certain patients or can alleviate symptoms of double vision in other patients. Prism can be edged into a lens base out (base towards ears), base in (base towards nose), base up, base down or in any direction. Interestingly, recent research has shown that in certain cases of poor balance due to concussion or traumatic brain injury, prisms can instantaneously help a patient walk upright and straight again.
7) The note section usually shows how long a prescription remains valid. In patients with certain eyes diseases that tend to progress rapidly or in children the prescriptions are usually only valid for 1 year. In healthy patients whose prescriptions haven't changed much in years, prescriptions are usually valid for 2 years. Other notes could include what type of lenses are required (progressives, bifocals, distance only, near only, etc.), refractive index of the lens (how dense the glass or plastic lens is), and/or lens coating recommendation (whether it's scratch resistant, UV blocking, blue blocking, or anti-reflective).
Σχόλια