Why do I have both shortsightedness and longsightedness?Eye & LASIK
It is not possible to have both short-sightedness (myopia) and long-sightedness (hypermetropia). It is more likely that you have a combination of myopia and presbyopia (old-sight, or the inability to read near objects). This is a situation that is commonly confused by many of my patients.
Myopic patients have an eye-ball that is longer than the refractive state of the eye, and hence require a negative / concave lens in order to see clearly for distance.
Hypermetropic patients have an eye-ball that is shorter than the refractive state of the eye, and hence require a positive / convex lens in order to see clearly for distance, however many young patients are able to "accommodate" (or increase the positive power of their internal lens) in order to overcome this refractive error if they are less than +3/+4 hyperopia.
Presbyopia is a condition where the internal lens of the eye has lost its ability to accommodate / increase its convexity in order to allow you to read near text / see near objects. Presbyopia occurs to ALL patients, both myopic and hypermetropic.
However hypermetropic patients are at an added disadvantage when they become presbyopic. They become symptomatic at a much earlier stage than myopic patients, and will need spectacle correction for distance and near. Myopic patients become symptomatic for presbyopia much later, as they continue to wear their spectacles for distance, and are able to read for near either by removing their spectacles (near-sightedness), or pushing their spectacles further down along their noses.
Hope this is helpful in clarifying your situation. For scenarios specific to your situation, you should consult your ophthalmologist!
An eye cannot be myopic (shortsighted) and hyperopic (longsighted) at the same time. But an eye can be myopic and presbyopic at the same time.
Hyperopia is not the same as presbyopia. Unfortunately, a lot of people get confused and call presbyopia longsightedness, when it is not.
Presbyopia is the loss of autofocusing power of the eye as the person gets older. Since the eye cannot autofocus, the person needs a certain spectacle power for distance, and a different spectacle power for near.
Hyperopia, or real longsightedness affects people differently. Mainly, hyperopia requires the eye to put in extra effort to focus (accommodate) for any particular distance.
For young people, hyperopia is usually not an issue, they usually do not need to wear glasses and they see everything clearly since they can accommodate a lot.
But as they get older, the (auto)focusing power gets less, and they will usually need reading glasses at a younger age, and then when they get even older they will also need progressives or different glasses for distance and near.
Short-sightedness is a type of refractive error where one is unable to see far well. It occurs in both the young and older people. Singapore has one of the highest prevalence of short-sightedness in the world.
Long-sightedness is another type of refractive error where one is unable to see near. Young people’s eyes with low levels of long-sightedness are able to accommodate which allow them to see without glasses. Akin to short-sightedness, it can occurs in both young and older people.
It is not possible to have the same eye to have both short-sightedness and long-sightedness. I believe what you are referring to is presbyopia, more commonly known as ‘lao hua’ in Mandarin. Presbyopia occurs when the natural lens in the eye loses its ability to accommodate and this usually only occurs to one who is aged 40 and above. A person with presbyopia will need reading glasses for near tasks.
It is advisable to visit an optometrist or an ophthalmologist to get fitted with a pair of glasses, should you experience difficulty seeing things far and/or near.
An Eye Surgeon's Guide To Reducing Singapore's Shortsightedness Problem (2019)
Singapore has one of the world’s highest rates of myopia (or shortsightedness). We spend $311.5 million on prescription glasses each year. More than...READ MORE