Optics of the Eye: From Visual Optics to Clinical Application

A special issue of Photonics (ISSN 2304-6732).

Deadline for manuscript submissions: closed (28 February 2023) | Viewed by 7574

Special Issue Editor

Center of Physics of the Universities of Minho and Porto, School of Sciences, University of Minho, 4710-057 Braga, Portugal
Interests: vision sciences; adaptative optics; optometry; instrumentation; ocular aberrations
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Accommodation is the ability of the eye to actively change its dioptric power to focus on objects at a wide range of distances. The focusing mechanism involves an increase in the total optical power of the eye to change from a distant to a near viewing distance and vice versa. This is primarily achieved through a change in the shape and thickness of the crystalline lens varying its optical refractive power.

The ocular wavefront aberrations (WA) and, consequently, the retinal image quality, depend on the balance between the optical properties of the cornea and crystalline lens, the two refractive media of the eye. Accommodation naturally changes this balance as it induces a change in lens geometrical and optical properties and, therefore, affects the optical quality of the retinal image.

Moreover, ocular accommodation decreases with age, leading to presbyopia and the need for eyeglasses or other devices to compensate for the lack of accommodation being the accommodative intra-ocular lens (IOL) one of the most recent developments in this area.

The existence of accommodative dysfunctions leads to symptoms and difficulties in performing near-vision tasks however, there are no studies relating these disabilities to the optical quality of the eye changes with accommodation.

In this Special Issue we expect to cover several topics regarding ocular accommodation:

  • Relationship between ocular accommodation and wavefront aberrations;
  • Changes in morphological and optical properties of the crystalline lens during accommodation;
  • New optical instrumentation or techniques to evaluate the ocular accommodation;
  • Impact of accommodative dysfunctions in the ocular optical quality;
  • Application of the knowledge;
  • New optical approaches to the presbyopia correction.

Dr. Sandra Franco
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Photonics is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (3 papers)

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Research

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9 pages, 623 KiB  
Communication
Spherical Aberration and Accommodative Insufficiency: Is There a Link?
Photonics 2023, 10(4), 452; https://doi.org/10.3390/photonics10040452 - 14 Apr 2023
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Abstract
Given the relationship between spherical aberrations and accommodation, the study of these aberrations can be helpful to understand accommodative response in subjects with accommodative dysfunctions. The purpose of this study was to evaluate on-axis and off-axis changes of primary and secondary spherical aberrations, [...] Read more.
Given the relationship between spherical aberrations and accommodation, the study of these aberrations can be helpful to understand accommodative response in subjects with accommodative dysfunctions. The purpose of this study was to evaluate on-axis and off-axis changes of primary and secondary spherical aberrations, Z(4,0) and Z(6,0), with accommodation in subjects with accommodative insufficiency (AI). Ten subjects with AI and eleven without any accommodative dysfunction (control) participated in this study. On-axis defocus Z(2,0), Z(4,0), and Z(6,0) were obtained in both groups with a Hartmann–Shack aberrometer for the unaccommodated state and with 1.00 D, 2.44 D, 3.83 D, and 4.73 D of accommodative stimuli. Z(4,0) and Z(6,0) were also measured on 11.5° and 23° temporal, nasal, superior, and inferior retinal areas for unaccommodated state and for 2.44 D of accommodative stimulus. In the control group, Z(4,0) became more negative with accommodation and Z(6,0) became more positive, as was expected according to previous studies. This tendency was not observed in the group of subjects with AI group for Z(4,0) or for Z(6,0). No differences on off-axis Z(4,0) and Z(6,0) were observed between the groups. The changes of spherical aberrations with accommodation seem different in subjects with AI compared to those without any accommodative dysfunction. Those with AI do not present a decrease in Z(4,0) and an increase in Z(6,0) with accommodation as occurs in eyes without this type of dysfunction. Understanding how the optics of the eye changes with accommodation can be helpful to understand the origin of accommodative dysfunctions. Full article
(This article belongs to the Special Issue Optics of the Eye: From Visual Optics to Clinical Application)
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13 pages, 4087 KiB  
Article
Lighting-Induced Changes in Central and Peripheral Retinal Thickness and Shape after Short-Term Reading Tasks in Electronic Devices
Photonics 2022, 9(12), 990; https://doi.org/10.3390/photonics9120990 - 16 Dec 2022
Cited by 3 | Viewed by 1909
Abstract
Background: To assess retinal and optical changes associated with near vision reading for different lighting conditions in electronic screens. Methods: Twenty-four young healthy subjects participated in the study; an iPad and an Ebook were chosen as stimuli for 5 min of reading task [...] Read more.
Background: To assess retinal and optical changes associated with near vision reading for different lighting conditions in electronic screens. Methods: Twenty-four young healthy subjects participated in the study; an iPad and an Ebook were chosen as stimuli for 5 min of reading task with different lighting conditions. Central and peripheral retinal thicknesses in the macular ETDRS areas by optical coherence tomography were analyzed. Results: Significant differences were found between basal retinal thickness and retinal thickness after reading with iPad and high illumination, in the N6 (p = 0.021) and I6 (p = 0.049) areas, and low illumination (S3: p = 0.008, N3: p = 0.018, I3: p = 0.021, N6: p = 0.018 and I6: p = 0.020), being thinner after reading. The same trend was observed after reading with an Ebook and high lighting in the N3 (p = 0.037) and N6 (p = 0.028). For low lighting conditions, only retinal thinning was observed. After reading, retinal shape analysis revealed significant changes from computed basal eccentricity for high lighting conditions only. At the periphery, those differences in eccentricity values were statistically significant for both lighting conditions. Conclusions: Young people can recover visual quality after 5 min of reading tasks at different lighting levels on electronic devices, while peripheral retinal expansion remains altered, especially at low lighting levels. Full article
(This article belongs to the Special Issue Optics of the Eye: From Visual Optics to Clinical Application)
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Review

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15 pages, 1949 KiB  
Review
Blue Light and Eye Damage: A Review on the Impact of Digital Device Emissions
Photonics 2023, 10(5), 560; https://doi.org/10.3390/photonics10050560 - 11 May 2023
Cited by 1 | Viewed by 4193
Abstract
The pandemic and lockdown caused by COVID-19 accelerated digitalization. Personal digital devices, emitting high-energy light, namely in the blue wavelength, have raised concerns about possible harmful effects on users’ eyes. Scientific research history has shown a relationship between exposure to blue light and [...] Read more.
The pandemic and lockdown caused by COVID-19 accelerated digitalization. Personal digital devices, emitting high-energy light, namely in the blue wavelength, have raised concerns about possible harmful effects on users’ eyes. Scientific research history has shown a relationship between exposure to blue light and changes in ocular structures. The main goal of this review is to examine frequent and prolonged exposure to blue radiation from computers, tablets and smartphones and its consequences on vision and ocular structures. Bibliographic research was carried out on changes induced by blue light in ocular structures, the cornea, the crystalline lens and the retina based on the following scientific databases: BioOne Complete™; Google Scholar™; Paperity™; PubMed™; and ScienceOpen™. The most significant studies on blue light and ocular damage were selected and reviewed. The most relevant bibliographic data were analyzed and summarized and some gaps in the theme of blue light from digital devices were identified. The experimental need to acquire additional new data is suggested. The hypothesis that continued use of digital devices enriched with blue light may interfere with the biological tissues of the cornea, crystalline lens, or retina is not clarified in the available scientific evidence. Therefore, additional studies are needed to answer this problem. Full article
(This article belongs to the Special Issue Optics of the Eye: From Visual Optics to Clinical Application)
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