How patient axial length, corneal power and effective lens position affect the near-vision with a multifocal lens
- Subhabrata Bhattacharya
- Nov 27, 2024
- 2 min read
Updated: Mar 14
Recently, Filomena and co-authors ( https://doi.org/10.1097/j.jcrs.0000000000001502 ) presented evidence based scientific classification of partial and full range vision lenses.
Based on their classification, I could summarize the following:
a) IOLs that provide more than 2.3 diopter of pseudo-accommodation at .2 log mar (6/9.5 or 20/32) in the defocus curve can be classified as full range of vision IOLs
b) IOLs that provide less than 2.3 diopter of pseudo-accommodation at .2 log mar in the defocus curve can be classified as 'partial-range of field vision' lens.
In the later category of lens, that is partial- range of field vision lens, that provides less than 2.3 diopter of pseudo-accommodation, the following categorization may be applicable:
i) Less than 1.2 diopter of pseudo- accommodation at .2 log mar - monofocal IOLs
ii) Between 1.2 diopter to 1.58 diopter of pseudo-accommodation at .2 log mar - enhanced monofocal IOL
iii) More than 1.58 diopter of pseudo-accommodation at .2 log mar- extended depth of field IOL
Since patients, axial length, pre operative anterior chamber depth (ACD) and Keratometry readings play a role in depth of field that the patient will get with any of the above category of IOLs, this calculator may help you determine the exact depth of field based on the patient biometry.
At the least, this calculator gives you an idea how the patient axial length, corneal power and effective lens position affect the add power in the corneal plane and how the effect add power of the multifocal IOL on the corneal plane impact the reading distance for the patient.
You can work on the below file, or access the calculator in the link here:
