Sergio Bonaque (CiViUM and Instituto Oftalmológico Amigó) has published a new manuscript in the Journal of Refractive Surgery in collaboration with the University of Oklahoma (USA). In this paper they indicate how to reduce the induction of spherical aberration in the hyperopic LASIK. These results are applicable when the WaveLight Allegretto platform is used, a very common refractive surgery laser used in Europe.
Recent research that the CiViUM carried out in colaboration with the department of Optics of the University of La Laguna has been published in one of the most prestigious journals of ophtalmology, the Journal of Refractive Surgery. It consisted of the simulation of the effects of a multifocal, assimetrical lens (Mplus) on vision when it was implanted in different orientations into the human eye.
The results indicate that when the surgery is personalized for each patient, an improvement of visual quality within the range from 20% to 121% can be achieved. This work may change the paradigm of premium cataract surgery, allowing for a significant improvement of results in the majority of patients. Link to the original article: here.
Ocular straylight has been measured by means of psychophysical methods over the years. This approach gives a functional parameter yielding a straight comparison with optically defined light scattering, and the Point Spread Function. This is of particular importance when the effect of intraocular lenses (IOLs) on postoperative straylight is sought. An optical system for straylight measurements of IOLs was adapted to a commercial device (C-Quant, Oculus), which employs such psychophysical method. A measurement principle of the proposed by the CiViUM group methodology along with the results of different IOL models have been recently published in the Journal of Biomedical Optics Express (G. Łabuz, F. Vargas-Martín, T.J.T.P. van den Berg, N. López-Gil, “Method for in vitro assessment of straylight from intraocular lenses,” Biomed. Opt. Express 6, 4457-4464)
Researchers at CiViUM presented their first experimental results on the effect of high-order aberrations in dynamic accommodation and a theoretical optical explanation for the larger lag found in myopes in comparison with emmetropes or hyperopes at The 15th International Myopia Conference that was hold on September 23-27, 2015 in Wenzhou, P. R. China. López-Gil et al. showed that clinical experiments can easily avoid artifactual apparent lag of perfectly accommodating axial myopic eye by choosing the appropriate reference plane.
Marín-Franch et al. presented the experimental results on effect of astigmatism and spherical aberration in dynamic accommodation. From these early stage results, astigmatism seemed to give cues for the sign of defocus in 2 out of 5 subject eyes, whereas spherical aberration did not. These are the first experimental results obtained with the MurciAO (the Murcia adaptive optics system in CiViUM’s lab) for the ERC project ERC-2012‐StG‐309416‐SACCO entitled “Signals for Accommodative Responses in Humans”, made in collaboration with the GIO group at the Universitat de Valencia and Phil Kruger from SUNY in New York. More information here.
CiViUM scientists have found that if the eye does not suffer the so-called Stiles-Crawford effect we would need more correction to observe nearby objects, due to the interaction with certain eye defects (aberrations). This effect produces that the light entering into the eye near the edge of the pupil is attenuated when reaching the retina.
This behavior is called apodization and in artificial systems, such as telescopes, is used to facilitate the detection of planets near bright stars.
In general, when observing distant objects the eye has positive spherical aberration. However, when the observed objects approach the eye, the change in the shape of the lens produces this aberration to decrease, usually becoming negative. The combination of the apodization with this change in sign produces that we have the best vision with lower correction than in the case the eye does not behave as described by the Stiles-Crawford effect. In this study the mathematical calculations needed to calculate the effect on any optical system affected of spherical aberration and apodization have been developed.
A recent publication from researchers of CiViUM group in the “Journal of Cataract and Refractive Surgery” gives explanation to undesirable effects suffered by some patients of cataract surgery, replacing its crystalline lens with and aspheric intraocular lens. This type of lens is specially designed with the aim to enhance images in the patient’s retina.
However, clinical studies show that some patients experience a worsening of their vision regarding the expected results. In the published paper it is shown through mathematical calculations that improper centering of the intraocular lens during operation causes a loss of quality in the patient’s vision. This study allows to know a priori for each aspheric lens design, the amount of decentration (tenths of a millimeter) that can be tolerated in the intervention in order to the special design of these lenses do not end up eroding the quality of the patient’s vision for what they were devised.
During the 4, 5 and 6th of September in Aguilas we celebrated the XII edition of the summer course “Current Issues in Vision Science: The International Year of Light”, directed by professors Vicente Fernández and Norberto López fron the University of Murcia. The course has reunited numerous researchers and professors from the field of vision sciences, including doctor José Manuel González Méijome, from the University of Minho (Braga, Portugal) with his talk about the progression of myopia. María Sagrario Millán García Varela from the Technical University of Cataluña gave a talk about the most recent intraocular lenses.
The members of the CIVIUM research group also gave interesting lectures. Diego López Alcón talked about various subjective and objective methods of addition, Vicente Fernández, a great professional in his field, talked about visual rehabilitation of children, and Francisco Lara spoke about the impact of luminosity on close vision. The students also participated in a workshop on refraction.
The next edition of the course awaits us the following year and all the information can be found on the official website (in Spanish) of the Universidad del Mar.
civium (from latin, genitive plural of civis-civis, "belong to the citizens")