PRESBYOPIA: AN AGE RELATED FAILING AUTOFOCUS
Presbyopia is the age-related loss of clear close vision. To see nearby clearly, the eye has to accommodate (make a focus) with 3 Dioptries. The ability to focus decreases as people ages due to the loss of elasticity of the lens. Presbyopia symptoms appear between the age of 45 (when the limit of 3 dioptries focusing necessary to see close clearly is reached) and 60 (when the eye isn’t able anymore to focus all.)
Surgeries to correct presbyopia
Currently, several techniques allow close vision restoration for the presbyopic patient. The choice will depend on the far vision defect, the age of the patient and his needs.
THE BASIC TECHNIQUE OF PRESBYLASIK
IS THE LASIK / FEMYOLASIK TECHNIQUE.
The added term "Presby" to form the name "PresbyLASIK" indicates that modifications are applied to the laser correction (ablation profile) in order to improve intermediate and near vision.
The operative complication rates are low (1%). The surgical risk is related to the creation of the corneal flap. This one is performed with an automated microkeratome in case of LASIK or a femtosecond laser in case of FemtoLASIK. The correction is then performed with the excimer laser.
This operation removes the far-sightedness defect and greatly improves the intermediate and near-sightedness. Between the age of 45 and 55 years old, the patient in most cases doesn’t need any glasses for far and near vision. Beyond the age of 55, a small reading correction will be needed for long lasting reading.
Learn more about the PresbyLASIK
URGERY OF CRYSTALLINE, MULTIFOCAL
INTRA-OCULAR LENSES AND "FIELD DEPTH"
The removal of the lens and its replacement with a "multifocal" lens or an EDOF “depth of field” lens can correct presbyopia.
The multifocal lens will give two sharp areas if it is bifocal (far and near) or three clear areas if it is trifocal (far, intermediate and near distance). The rings present in the optics of these implants can be the source of a contrast reduction and a halo perception around light sources.
The Depth Of Focus or Depth of Field lens works the same way as the PresbyLASIK, combining the increase of the sharp depth of field vision with better visual quality in far and intermediate vision such as the multifocal lens, but with less effective near vision.
Learn more about lens surgery, multifocal implants and EDOF
Monovision is an interesting surgical solution, especially for myopic patients.
Most myopic patients have heard that myopia "balances" over time. In reality, myopia stabilizes between 20 and 25 years old. After 45 years old, when presbyopia appears, the myopic realizes that it is harder to read with his glasses or lenses. But reading is still possible when the patient removes his glasses (at least in case of light myopia) because the shortsighted eye does not have to focus for near vision, it can see clear close-up at rest.
The myopic can take advantage of this thanks to monovision. One eye is totally corrected for far-sightedness, the other one is left slightly myopic to allow near-sightedness. This is called monovision.
Monovision is an excellent solution for some patients but it is not suitable for everyone. A preliminary test with a contact lens makes it possible to select the right candidates.
f the test is conclusive, a surgical correction can be performed by :