Mohammad Taghi Fathi
- Name and Nationality
Mohammad Taghi Fathi (Iran)
- Experienced Researcher at Rodenstock GmbH, Munich, Germany (Partner 06)
- Start date:
- Principal Investigator:
Anne Seidemann / Gregor Esser
Diurnal variations of visual performance and Role of ocular chromatic aberration of the eye optics on vision
My study within this project has two major aims:
- The role of transversal chromatic aberration (TCA) induced by spectacle lenses and the subject’s ability to adapt to TCA
- The investigation of the diurnal variations of refraction and visual performances.
- Transversal chromatic aberration (TCA) is dependent on refractive power, lens material and eccentric position in the lens. Spectacle wearers with higher refractive errors realize this effect when looking through eccentric parts of lenses with high refractive index.
The objective of this project is to evaluate how subjects deal with induced TCA. Which amount of TCA is acceptable for subjects? Are there individual differences that are of interest for the development of spectacle lenses? To study this major point, lenses with different TCA will be developed and provided to the network partners to study by subjective tests whether there is adaptation to TCA.
Since the eyes move, the amount of TCA changes continuously by looking through different parts of the lenses. Is it possible to adapt to TCA in the presence of eye movements – even if TCA is just apparent with eccentric gaze directions? Are there inter-individual differences or correlations between refractive groups, lens materials or individual eye– and head movement characteristics?
- The second part of my project is to study the diurnal variations of visual performances in collaboration with the other ER (Dr. Yohann Benard). Indeed, recent reports demonstrate that different parameters of eye media (e.g. intraocular pressure, axial length, …) may fluctuate during the day so that the eye perceives variable visual performance during the day. To assess diurnal variations of refraction, we will measure the subjective and objective (i.e. Hartmann-Shack based method) refractions with different methods, corresponding visual performances, and axial length of the eye, at several moments of the day. Eye length will be measured in collaboration with OpAL partner 01. Goal of the study is a better understanding of circumstances that influence the refraction and about the best refraction for optical corrections over the whole day – with regard of possible adaptational processes.