Final Report Summary - ADV VISUAL OPTICS (Advanced Visual Optics)
FINAL SUMMARY REPORT
The aim of the project was to provide a description of the optics of the eye at the different cycles of life and to help in the development of new optical interventions against myopia. Both aspects have been combined together in the development of new laboratory instrumentation that could provide new assessments of the many different aspect in the optics of the eye.
Following these two lines, the main achievements are listed below:
Myopia and peripheral optics of the human eye
Before a serious optical intervention in myopia is applied, there should be enough optical information of the subjects who suffer the disease. In this context, peripheral refraction is one of the ocular variables that are proposed as a target for an optical intervention. It is expected that superimposing peripheral myopia to the eccentric retina has the effect to stop the central retina growing or at least to slow down retinal elongation. However in the first clinical trials performed on asian countries the superimposed peripheral myopia had a fixed amount of myopic diopters for all subject in the trials, which lead to a relatively low success of the experiment. From the beginning of the project we have been working in the direction to explain these results.
- We have explained how peripheral refraction suffers a high variability across a population and performed a group classification of the different types of profiles. That explained why a fixed amount of peripheral myopia imposed on the retina would only have a relative success across the whole population. Our work suggested that individual measurements and solutions should be performed instead of a general solution for all myopes.
- A new Hartmann-Shack peripheral sensor was developed. The new method was systematically compared to a previous established instrument performing faster and adding some additional information that other methods are not able to measure.
- We explored peripheral optic in subjects who had cataract surgery on his eyes. We discovered that after implanting an intraocular lens, there was in average a two diopters myopic shift in peripheral refraction. This result opens the question of better designed intraocular lenses for the periphery and suggest that there is still some possibilities of improving vision with better optical designs.
Optics of the human eye at different stages of life
Concerning the research line that implies the optics of the eye across a cycle of life, we have provide advances in different aspects of research either basic or instrumental.
- We have completed the description of the aging eye adding the new variable of ocular alignment. Our results implied that geometrical changes in the crystalline lens with age contributed to modify its aberration structure, reducing the compensation mechanism and explaining most of the measured increment of ocular aberrations with age. Ocular alignment remained mostly stable with age.
- We have also performed optical modelling of the changes of aberrations with age to try to identify those geometrical variations in the crystalline lens that contribute to aging. We found that the increase in SA with age could only be explained as a consequence of an increase in the conic constant of the lens and/or additional changes on the gradient index. The models agreed well with published data.
- Focusing on a typical aging disease as presbyopia, we developed a new instrument to measure the stability of the human lens. This instrument has interest to study the accommodation state of the crystalline lens and the disease of presbyopia. Helmholtz theory of accommodation predicts that under the maximum accommodation state, the ciliary body release tension on the zonule, therefore leaving the crystalline lens with less tensional forces that attach the lens mass to the eye orbit and in general with less mechanical stability. With the new prototype we pretend to study this effect in a population as a function of age.
Our instrument uses a high temporal resolution CMOS camera sensor attached to a telecentric lens and a semicircular ring of IR LEDs placed on the lens aperture to generate Purkinje images. The images are recorded immediately after the eye performs a saccadic eye movement of 9 degrees. Oscillations in the positions of lens and corneal reflections are used to calculate the stabilization time and amplitude of the lens movement.
Conclusions and future research prospects
There has been advances in myopia research that established peripheral optics as an important variable to study the progression of the disease. However little success has been found so far in the clinical studies. The huge variability of peripheral refraction reported in this project will be important for the near future clinical trials. A better personalized optical solution should be relevant to establish the success rate of new therapies.
Concerning the aging eye, there is still lot of work to perform mainly on the presbyopic eye and its different optical solutions. Also, the human optics through a cycle of life will not be complete unless a study was performed to include children and infants. It will require high technical, management and ethics efforts, but the benefits of understanding the development of human optics are still huge.
The aim of the project was to provide a description of the optics of the eye at the different cycles of life and to help in the development of new optical interventions against myopia. Both aspects have been combined together in the development of new laboratory instrumentation that could provide new assessments of the many different aspect in the optics of the eye.
Following these two lines, the main achievements are listed below:
Myopia and peripheral optics of the human eye
Before a serious optical intervention in myopia is applied, there should be enough optical information of the subjects who suffer the disease. In this context, peripheral refraction is one of the ocular variables that are proposed as a target for an optical intervention. It is expected that superimposing peripheral myopia to the eccentric retina has the effect to stop the central retina growing or at least to slow down retinal elongation. However in the first clinical trials performed on asian countries the superimposed peripheral myopia had a fixed amount of myopic diopters for all subject in the trials, which lead to a relatively low success of the experiment. From the beginning of the project we have been working in the direction to explain these results.
- We have explained how peripheral refraction suffers a high variability across a population and performed a group classification of the different types of profiles. That explained why a fixed amount of peripheral myopia imposed on the retina would only have a relative success across the whole population. Our work suggested that individual measurements and solutions should be performed instead of a general solution for all myopes.
- A new Hartmann-Shack peripheral sensor was developed. The new method was systematically compared to a previous established instrument performing faster and adding some additional information that other methods are not able to measure.
- We explored peripheral optic in subjects who had cataract surgery on his eyes. We discovered that after implanting an intraocular lens, there was in average a two diopters myopic shift in peripheral refraction. This result opens the question of better designed intraocular lenses for the periphery and suggest that there is still some possibilities of improving vision with better optical designs.
Optics of the human eye at different stages of life
Concerning the research line that implies the optics of the eye across a cycle of life, we have provide advances in different aspects of research either basic or instrumental.
- We have completed the description of the aging eye adding the new variable of ocular alignment. Our results implied that geometrical changes in the crystalline lens with age contributed to modify its aberration structure, reducing the compensation mechanism and explaining most of the measured increment of ocular aberrations with age. Ocular alignment remained mostly stable with age.
- We have also performed optical modelling of the changes of aberrations with age to try to identify those geometrical variations in the crystalline lens that contribute to aging. We found that the increase in SA with age could only be explained as a consequence of an increase in the conic constant of the lens and/or additional changes on the gradient index. The models agreed well with published data.
- Focusing on a typical aging disease as presbyopia, we developed a new instrument to measure the stability of the human lens. This instrument has interest to study the accommodation state of the crystalline lens and the disease of presbyopia. Helmholtz theory of accommodation predicts that under the maximum accommodation state, the ciliary body release tension on the zonule, therefore leaving the crystalline lens with less tensional forces that attach the lens mass to the eye orbit and in general with less mechanical stability. With the new prototype we pretend to study this effect in a population as a function of age.
Our instrument uses a high temporal resolution CMOS camera sensor attached to a telecentric lens and a semicircular ring of IR LEDs placed on the lens aperture to generate Purkinje images. The images are recorded immediately after the eye performs a saccadic eye movement of 9 degrees. Oscillations in the positions of lens and corneal reflections are used to calculate the stabilization time and amplitude of the lens movement.
Conclusions and future research prospects
There has been advances in myopia research that established peripheral optics as an important variable to study the progression of the disease. However little success has been found so far in the clinical studies. The huge variability of peripheral refraction reported in this project will be important for the near future clinical trials. A better personalized optical solution should be relevant to establish the success rate of new therapies.
Concerning the aging eye, there is still lot of work to perform mainly on the presbyopic eye and its different optical solutions. Also, the human optics through a cycle of life will not be complete unless a study was performed to include children and infants. It will require high technical, management and ethics efforts, but the benefits of understanding the development of human optics are still huge.