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Papachristou A, Lambraki A, Giannakopoulou T, Tsilimbaris MK, Plainis S. Silicone oil insulation effects on flash electroretinogram and visual evoked potential in patients with retinal detachment. J Optom 2024; 17:100502. [PMID: 37931571 PMCID: PMC10654225 DOI: 10.1016/j.optom.2023.100502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 09/20/2023] [Accepted: 10/16/2023] [Indexed: 11/08/2023]
Abstract
BACKGROUND Silicone oil is used as endotamponade following vitreoretinal surgery to maintain the retina reattached when indicated. This study investigates the hypothesis that silicone oil causes insulation effects on the retina by affecting its response to light. METHODS Electrophysiological responses to a flash stimulus were recorded using full-field electroretinography (ERG) and visual evoked potentials (VEP). Recordings were performed in 9 patients who underwent surgery for retinal detachment, before (1-2 days) and after (2-3 weeks) silicone oil removal (SOR) in both the study and the control eye. Flash ERG and VEP recordings were performed according to the ISCEV standard protocol. RESULTS Statistically significant differences were found in the study eye in the amplitudes of the ERG responses and their corresponding ratios, i.e. the amplitude after SOR over the amplitude before SOR, in all conditions tested. No differences were observed in the control eye. The mean ratio of photopic ERG response was 3.4 ± 2.4 for the study and 1.0 ± 0.3 for the control eye (p<0.001). The mean ratio of ERG flicker response was 3.1 ± 2.4 and 1.0 ± 0.3, respectively (p = 0.003). Scotopic flash ERG ratio was 5.0 ± 4.4 for the study and 1.3 ± 0.6 for the control eye (p = 0.012). No differences were observed for the amplitude and latency of flash VEP response after SOR. CONCLUSIONS Silicone oil causes a reduction in flash ERG responses; no effect was found on flash VEP responses. ERGs in eyes filled with silicone oil should not be considered representative of retinal functionality, in contrast to VEPs, which are not affected by silicone oil presence.
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Affiliation(s)
- Anastasia Papachristou
- Laboratory of Optics and Vision (LOV), School of Medicine, University of Crete, Greece
- Ophthalmology Department, University Hospital of Heraklion, Crete, Greece
| | - Argiri Lambraki
- Laboratory of Optics and Vision (LOV), School of Medicine, University of Crete, Greece
| | - Trisevgeni Giannakopoulou
- Laboratory of Optics and Vision (LOV), School of Medicine, University of Crete, Greece
- Ophthalmology Department, University Hospital of Heraklion, Crete, Greece
| | - Miltiadis K. Tsilimbaris
- Laboratory of Optics and Vision (LOV), School of Medicine, University of Crete, Greece
- Ophthalmology Department, University Hospital of Heraklion, Crete, Greece
| | - Sotiris Plainis
- Laboratory of Optics and Vision (LOV), School of Medicine, University of Crete, Greece
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Vermisoglou EC, Giannakopoulou T, Todorova N, Vaimakis T, Boukos N, Petridis D, Trapalis C. 2-Dimensional Clay/Reduced Graphene Oxide Ordered Heterostructures Dispersible in Water via a One-Step Hydrothermal Route. J Nanosci Nanotechnol 2018; 18:4684-4691. [PMID: 29442646 DOI: 10.1166/jnn.2018.15334] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
A facile and green method for trapping the hydrophobic reduced graphene oxide between the hydrophilic Kunipia F layers in order to attain stable aqueous dispersions of reduced graphene oxide is described. Initially stable aqueous dispersions of hydrophilic clay intercalated with hydrophilic graphene oxide sheets were formed providing well-organized heterostructures, as it was revealed by scanning electron microscopy images. These structures were preserved in the product obtained after hydrothermal treatment where the hydrophilic graphene oxide was converted to hydrophobic reduced graphene oxide. Ultraviolet measurements revealed the aforementioned conversion which was accompanied by a characteristic change in color from yellow-brown to black in the corresponding aqueous dispersions of these hybrids before and after hydrothermal treatment. The stability of these homogeneous dispersions was confirmed by Zeta Potential measurements implying interactions both in cases of graphene oxide and reduced graphene oxide with clay sheets that made feasible the effective interstratification of graphene-clay layered materials. In these stable dispersions chemistry in aqueous environment could be fully utilized making possible their incorporation e.g., as fillers to hydrophilic polymeric matrices extending thus the limits of application.
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Affiliation(s)
- E C Vermisoglou
- Institute of Nanoscience and Nanotechnology (INN), NCSR "Demokritos", 15343, Agia Paraskevi, Attikis, Greece
| | - T Giannakopoulou
- Institute of Nanoscience and Nanotechnology (INN), NCSR "Demokritos", 15343, Agia Paraskevi, Attikis, Greece
| | - N Todorova
- Institute of Nanoscience and Nanotechnology (INN), NCSR "Demokritos", 15343, Agia Paraskevi, Attikis, Greece
| | - T Vaimakis
- Department of Chemistry, University of Ioannina, P.O. Box 1186, Ioannina, Greece
| | - N Boukos
- Institute of Nanoscience and Nanotechnology (INN), NCSR "Demokritos", 15343, Agia Paraskevi, Attikis, Greece
| | - D Petridis
- Institute of Nanoscience and Nanotechnology (INN), NCSR "Demokritos", 15343, Agia Paraskevi, Attikis, Greece
| | - C Trapalis
- Institute of Nanoscience and Nanotechnology (INN), NCSR "Demokritos", 15343, Agia Paraskevi, Attikis, Greece
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Karapati S, Giannakopoulou T, Todorova N, Boukos N, Papailias I, Dimotikali D, Trapalis C. Novel ‘Pickering’ modified TiO 2 photocatalysts with high De-NOx efficiency. Catal Today 2017. [DOI: 10.1016/j.cattod.2017.01.044] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Bontzos G, Plainis S, Papadaki E, Giannakopoulou T, Detorakis E. Mechanical optic neuropathy in high myopia. Clin Exp Optom 2017; 101:613-615. [PMID: 28503855 DOI: 10.1111/cxo.12548] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 02/21/2017] [Accepted: 02/25/2017] [Indexed: 01/30/2023] Open
Affiliation(s)
- Georgios Bontzos
- Department of Ophthalmology, University Hospital of Heraklion, Heraklion, Greece.,Institute of Vision and Optics, University of Crete, Heraklion, Greece
| | - Sotiris Plainis
- Department of Ophthalmology, University Hospital of Heraklion, Heraklion, Greece.,Institute of Vision and Optics, University of Crete, Heraklion, Greece.,Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Efrosini Papadaki
- Department of Radiology, University Hospital of Heraklion, Heraklion, Greece
| | - Trisevgeni Giannakopoulou
- Department of Ophthalmology, University Hospital of Heraklion, Heraklion, Greece.,Institute of Vision and Optics, University of Crete, Heraklion, Greece
| | - Efstathios Detorakis
- Department of Ophthalmology, University Hospital of Heraklion, Heraklion, Greece.,Institute of Vision and Optics, University of Crete, Heraklion, Greece
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Plainis S, Petratou D, Giannakopoulou T, Radhakrishnan H, Pallikaris IG, Charman WN. Small-aperture monovision and the Pulfrich experience: absence of neural adaptation effects. PLoS One 2013; 8:e75987. [PMID: 24155881 PMCID: PMC3796532 DOI: 10.1371/journal.pone.0075987] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2013] [Accepted: 08/19/2013] [Indexed: 11/19/2022] Open
Abstract
PURPOSE To explore whether adaptation reduces the interocular visual latency differences and the induced Pulfrich effect caused by the anisocoria implicit in small-aperture monovision. METHODS Anisocoric vision was simulated in two adults by wearing in the non-dominant eye for 7 successive days, while awake, an opaque soft contact lens (CL) with a small, central, circular aperture. This was repeated with aperture diameters of 1.5 and 2.5 mm. Each day, monocular and binocular pattern-reversal Visual Evoked Potentials (VEP) were recorded. Additionally, the Pulfrich effect was measured: the task of the subject was to state whether a a 2-deg spot appeared in front or behind the plane of a central cross when moved left-to-right or right-to-left on a display screen. The retinal illuminance of the dominant eye was varied using neutral density (ND) filters to establish the ND value which eliminated the Pulfrich effect for each lens. All experiments were performed at luminance levels of 5 and 30 cd/m(2). RESULTS Interocular differences in monocular VEP latency (at 30 cd/m(2)) rose to about 12-15 ms and 20-25 ms when the CL aperture was 2.5 and 1.5 mm, respectively. The effect was more pronounced at 5 cd/m(2) (i.e. with larger natural pupils). A strong Pulfrich effect was observed under all conditions, with the effect being less striking for the 2.5 mm aperture. No neural adaptation appeared to occur: neither the interocular differences in VEP latency nor the ND value required to null the Pulfrich effect reduced over each 7-day period of anisocoric vision. CONCLUSIONS Small-aperture monovision produced marked interocular differences in visual latency and a Pulfrich experience. These were not reduced by adaptation, perhaps because the natural pupil diameter of the dominant eye was continually changing throughout the day due to varying illumination and other factors, making adaptation difficult.
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Affiliation(s)
- Sotiris Plainis
- Institute of Vision & Optics (IVO), University of Crete, Heraklion, Greece
- Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
- * E-mail:
| | - Dionysia Petratou
- Institute of Vision & Optics (IVO), University of Crete, Heraklion, Greece
| | | | - Hema Radhakrishnan
- Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
| | | | - W. Neil Charman
- Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
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Todorova N, Vaimakis T, Petrakis D, Hishita S, Boukos N, Giannakopoulou T, Giannouri M, Antiohos S, Papageorgiou D, Chaniotakis E, Trapalis C. N and N,S-doped TiO2 photocatalysts and their activity in NOx oxidation. Catal Today 2013. [DOI: 10.1016/j.cattod.2012.11.019] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Giannakopoulou T, Plainis S, Pallikaris IG, Tsilimbaris MK. Contrast sensitivity in the ‘good eye’ of adult patients with severe impairment in the other eye. Ophthalmic Physiol Opt 2013; 33:150-6. [DOI: 10.1111/opo.12026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 01/03/2013] [Indexed: 10/27/2022]
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Anastasakis A, Plainis S, Giannakopoulou T, Papadimitraki E, Fanouriakis C, Tsilimbaris MK. Xerophthalmia and acquired night blindness in a patient with a history of gastrointestinal neoplasia and normal serum vitamin A levels. Doc Ophthalmol 2013; 126:159-62. [DOI: 10.1007/s10633-012-9370-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 12/18/2012] [Indexed: 11/28/2022]
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Plainis S, Petratou D, Giannakopoulou T, Radhakrishnan H, Pallikaris IG, Charman WN. Interocular differences in visual latency induced by reduced-aperture monovision. Ophthalmic Physiol Opt 2012; 33:123-9. [PMID: 23278194 DOI: 10.1111/opo.12018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 11/12/2012] [Indexed: 11/28/2022]
Abstract
PURPOSE To explore the interocular differences in the temporal responses of the eyes induced by the monocular use of small-aperture optics designed to aid presbyopes by increasing their depth-of-focus. METHODS Monocular and binocular pattern-reversal visual evoked potentials (VEPs) were measured at a mean photopic field luminance of 30 cd/m(2) in seven normal subjects with either natural pupils or when the non-dominant eye wore a small-aperture contact lens (aperture diameter 1.5, 2.5 or 3.5 mm, or an annular opaque stop of inner and outer diameters 1.5 and 4.0 mm respectively). Responses were also measured with varying stimulus luminance (5, 13.9, 27.2 and 45 cd/m(2)) and a fixed 3.0 mm artificial pupil. RESULTS Mean natural pupil diameters were 4.7 and 4.4 mm under monocular and binocular conditions respectively. The small-aperture contact lenses reduced the amplitude of the P100 component of the VEP and increased its latency. Inter-ocular differences in latency rose to about 20-25 ms when the pupil diameter of the non-dominant eye was reduced to 1.5 mm. The measurements with fixed pupil and varying luminance suggested that the observed effects were explicable in terms of the changes in retinal illuminance produced by the restrictions in pupil area. CONCLUSIONS The anisocoria induced by small-aperture approaches to aid presbyopes produces marked interocular differences in visual latency. The literature of the Pulfrich effect suggests that such differences can lead to distortions in the perception of relative movement and, in some cases, to possible hazard.
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Affiliation(s)
- Sotiris Plainis
- Institute of Vision and Optics, School of Health Sciences, University of Crete, Crete, Greece.
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Plainis S, Petratou D, Giannakopoulou T, Radhakrishnan H, Pallikaris IG, Charman WN. Reduced-aperture monovision for presbyopia and the Pulfrich effect. J Optom 2012; 5:156-163. [PMCID: PMC3860761 DOI: 10.1016/j.optom.2012.06.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 06/18/2012] [Indexed: 06/09/2023]
Abstract
Purpose Monocular use of reduced-aperture optics in the form of a corneal inlay or contact lens may improve near vision of presbyopes by increasing their depth-of-focus (DOF). However, the associated induced interocular differences in retinal illuminance may cause distortion in spatial perception due to the Pulfrich effect. Methods Three young subjects were used to explore the Pulfrich effect during reduced-aperture monovision using afocal contact lenses (in the non-dominant eye) which were either opaque with a central clear aperture of 1.5, 2.5 or 3.5 mm diameter, or had an annular opaque stop of inner and outer diameters 1.5 and 4.0 mm, respectively. The two-alternative forced choice (2AFC) task of the subject was to state whether a 2° circular spot appeared in front or behind the plane of a central cross when moved left-to-right or right-to-left. The retinal illuminance of the dominant eye was varied using neutral density (ND) filters to establish the ND value which eliminated the Pulfrich effect for each lens. Results The Pulfrich effect was observed with all the lenses. The ND value required to null the effect decreased as the diameter of the aperture of the lenses increased. A reasonably good agreement was found between observed ND values for the different lenses and those predicted from the relative areas of the effective pupils of the two eyes. Minor discrepancies were attributed to decentration of the contact lenses with respect to the natural pupils. Conclusions Reduced-aperture monovision generates marked Pulfrich-type distortions in spatial perception under conditions where the visual world is changing dynamically as a result of movement.
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Affiliation(s)
- Sotiris Plainis
- Institute of Vision and Optics (IVO), School of Health Sciences, University of Crete, Greece
| | - Dionysia Petratou
- Institute of Vision and Optics (IVO), School of Health Sciences, University of Crete, Greece
| | | | | | - Ioannis G. Pallikaris
- Institute of Vision and Optics (IVO), School of Health Sciences, University of Crete, Greece
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Plainis S, Petratou D, Giannakopoulou T, Atchison DA, Tsilimbaris MK. Binocular summation improves performance to defocus-induced blur. Invest Ophthalmol Vis Sci 2011; 52:2784-9. [PMID: 21228386 DOI: 10.1167/iovs.10-6545] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To assess whether there are any advantages of binocular over monocular vision under blur conditions. METHODS The effect of defocus, induced by positive lenses, was measured on the pattern reversal visual evoked potential (VEP) and on visual acuity (VA). Monocular (dominant eye) and binocular VEPs were recorded from 13 volunteers (average age, 28 ± 5 years; average spherical equivalent, -0.25 ± 0.73 D) for defocus up to 2.00 D using positive powered lenses. VEPs were elicited using reversing 10 arcmin checks (4 reversals/s). The stimulus subtended a circular field of 7° with 100% contrast and mean luminance 30 cd/m(2). VA was measured under the same conditions using ETDRS charts. All measurements were performed at 1 m viewing distance with best spectacle sphero-cylindrical correction and natural pupils. RESULTS With binocular stimulation, amplitudes and implicit times of the P100 component of the VEPs were greater and shorter, respectively, in all cases than for monocular stimulation. Mean binocular enhancement ratio in the P100 amplitude was 2.1 in focus, increasing linearly with defocus to be 3.1 at +2.00 D defocus. Mean peak latency was 2.9 ms shorter in focus with binocular than for monocular stimulation, with the difference increasing with defocus to 8.8 ms at +2.00 D. As for the VEP amplitude, VA was always better with binocular than with monocular vision, with the difference being greater for higher retinal blur. CONCLUSIONS Both subjective and electrophysiological results show that binocular vision ameliorates the effect of defocus. The increased binocular facilitation observed with retinal blur may be due to the activation of a larger population of neurons at close-to-threshold detection under binocular stimulation.
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Affiliation(s)
- Sotiris Plainis
- Institute of Vision & Optics, School of Health Sciences, University of Crete, Crete, Greece.
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Plainis S, Moschandreas J, Nikolitsa P, Plevridi E, Giannakopoulou T, Vitanova V, Tzatzala P, Pallikaris IG, Tsilimbaris MK. Myopia and visual acuity impairment: a comparative study of Greek and Bulgarian school children. Ophthalmic Physiol Opt 2009; 29:312-20. [DOI: 10.1111/j.1475-1313.2009.00654.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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