Silicone oil insulation effects on flash electroretinogram and visual evoked potential in patients with retinal detachment / Efectos del aislamiento del aceite de silicona sobre el electrorretinograma flash y el potencial evocado visual en pacientes con desprendimiento de retina

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.(AU)

A novel vector field analysis for quantitative structure changes after macular epiretinal membrane surgery.

The aim of this study was to introduce novel vector field analysis for the quantitative measurement of retinal displacement after epiretinal membrane (ERM) removal. We developed a novel framework to measure retinal displacement from retinal fundus images as follows: (1) rigid registration of preoperative retinal fundus images in reference to postoperative retinal fundus images, (2) extraction of retinal vessel segmentation masks from these retinal fundus images, (3) non-rigid registration of preoperative vessel masks in reference to postoperative vessel masks, and (4) calculation of the transformation matrix required for non-rigid registration for each pixel. These pixel-wise vector field results were summarized according to predefined 24 sectors after standardization. We applied this framework to 20 patients who underwent ERM removal to obtain their retinal displacement vector fields between retinal fundus images taken preoperatively and at postoperative 1, 4, 10, and 22 months. The mean direction of displacement vectors was in the nasal direction. The mean standardized magnitudes of retinal displacement between preoperative and postoperative 1 month, postoperative 1 and 4, 4 and 10, and 10 and 22 months were 38.6, 14.9, 7.6, and 5.4, respectively. In conclusion, the proposed method provides a computerized, reproducible, and scalable way to analyze structural changes in the retina with a powerful visualization tool. Retinal structural changes were mostly concentrated in the early postoperative period and tended to move nasally.

Surgical management of a case of giant retinal tear with closed funnel retinal detachment in a pediatric patient.

BACKGROUND: A 7-year-old male child was brought by his parents with a complaint of low vision in both eyes for 2 months. The child had low vision in both the eyes for 1.5 years, but the parents noticed when it worsened further 2 months back, leading to profound vision loss. On ophthalmic evaluation, the child did not perceive light in the right eye. Furthermore, anterior segment examination showed complicated cataract and open funnel retinal detachment with intra-retinal cysts in ultrasound (USG) B scan. In the left eye, he could appreciate light but with poor fixation. Fundus evaluation of the left eye showed total retinal detachment on indirect ophthalmoscopy, which was confirmed on USG B scan. Since the right eye had poor visual potential, no intervention was done. The left eye underwent pars plana vitrectomy with silicone oil tamponade, which led to successful anatomical outcomes. The immediate and late postoperative periods were uneventful, and the child was kept under follow-up and was observed closely. PURPOSE: To educate regarding the surgical management of giant retinal tears in a pediatric patient. SYNOPSIS: To inform regarding the surgical challenges faced and steps adopted to manage such cases. HIGHLIGHTS: Through this case, we want to highlight the challenges faced, such as delayed presentation, difficult preoperative evaluation, intraoperative difficulties such as mobile retina, absence of posterior vitreous detachment, and tenacious vitreous gel. We also want to emphasize on the steps taken to overcome the challenges. CONCLUSION: In such challenging situations, effective planning, careful manipulation, and persistence are essential for success. VIDEO LINK: https://youtu.be/T0Gy6Wj13zI.

Real-Time Temperature-Controlled Retinal Laser Irradiation in Rabbits.

Purpose: Subdamaging thermal retinal laser therapy has the potential to induce regenerative stimuli in retinal diseases, but validated dosimetry is missing. Real-time optoacoustic temperature determination and control could close this gap. This study investigates a first in vivo application. Methods: Two iterations of a control module that were optically coupled in between a continuous-wave commercial laser source and a commercial slit lamp were evaluated on chinchilla rabbits. The module allows extraction of the temperature rise in real time and can control the power of the therapy laser such that a predefined temperature rise at the retina is quickly achieved and held constant. Irradiations with aim temperatures from 45°C to 69°C were performed on a diameter of 200 µm and a heating time of 100 ms. Results: We analyzed 424 temperature-guided irradiations in nine eyes of five rabbits. The mean difference between the measured and aim temperature was -0.04°C ± 0.98°C. The following ED50 values for visibility thresholds could be determined: 58.6°C for funduscopic visibility, 57.7°C for fluorescein angiography, and 57.0°C for OCT. In all measurements, the correlation of tissue effect was higher to the temperature than to the average heating laser power used. Conclusions: The system was able to reliably perform temperature-guided irradiations, which allowed for better tissue effect control than simple power control. This approach could enhance the accuracy, safety, and reproducibility of thermal stimulating laser therapy. Translational Relevance: This study is a bridge between preclinical ex vivo experiments and a pilot clinical study.

Role of Optical Coherence Tomography in Predicting Visual Outcome after Surgery for Sellar and Supra-Sellar Tumors.

BACKGROUND: Almost one-fifth of patients undergoing surgery for sellar/supra-sellar tumors do not gain a significant improvement in their vision. Various methods have been described to predict prospective visual outcomes in them, although they lack uniformity. OBJECTIVE: The study was conducted to predict visual outcomes following surgery for sellar and supra-sellar tumors compressing the anterior optic pathway based on pre-operative optical coherence tomography (OCT) parameters. METHODS AND MATERIALS: This was a record-based observational descriptive longitudinal study done in a tertiary care center in India. Thirty-seven patients (74 eyes) diagnosed with sellar supra-sellar lesions were included in the study. Patients' ophthalmic evaluations, done pre-operatively and 3 months post-operatively, were reviewed. Spectral-domain OCT and segmentation were done using the automated segmentation technology of Spectralis software. The thickness of the respective layers was measured. RESULTS AND CONCLUSIONS: The mean age of the study population was 42.68 years. Eyes with a pre-operative visual acuity component of VIS (visual impairment score) ≤61, pre-operative ganglion cell layer thickness ≥26.31 um, a pre-operative inner plexiform layer thickness of ≥25.69 um, a pre-operative ganglion cell inner plexiform layer thickness of 52.00 um, pre-operative ganglion cell complex thickness ≥84.47 µm, and a pre-operative inner retinal layer thickness of ≥205.25 µm were more likely to have an improved visual outcome. Eyes with a pre-operative duration of visual symptoms of ≥15 months, VIS ≥126.50, a pre-operative decimal visual acuity of <0.035, a pre-operative visual field index of ≤8%, a pre-operative macular thickness of ≤287.06 um, a pre-operative macular RNFL (retinal nerve fiber layer) thickness ≤66.00 µm, and a pre-operative peri-papillary RNFL thickness ≤64.62 µm were unlikely to have visual improvement.

Pars Plana Vitrectomy in the Treatment of Rhegmatogenous Retinal Detachment.

AIM: The aim of the study is to retrospectively evaluate the anatomical success rate and functional results of 25G+ PPV in the treatment of newly diagnosed rhegmatogenous retinal detachment (RRD). MATERIAL AND METHODS: The set consists of 152 eyes of 152 patients, of which 71 (47%) were men, average age 54 years, operated on by one surgeon for RRD at the Eye Clinic of the University Hospital and Medical Faculty of Masaryk University Brno from 1.7.2019 to 4.5.2021 using the 25G+ PPV technique. 25G+ PPV with pre-equatorial cerclage was performed on 7 patients. The patients' anamnesis included blunt ocular trauma and uncomplicated cataract surgery with implantation of a posterior chamber intraocular lens. The cause of RRD was retinal tear/s, regardless of their number and location. The transparency of the anterior segment of the eye enabled reliable visualization of the posterior segment. Preoperative proliferative vitreoretinopathy (PVR) grade A-D2 was admissible. Patients with a history of penetrating ocular trauma were excluded. The postoperative findings and functional outcomes of the patients were evaluated 1-3 months after PPV. The operation was anatomically successful if the retina was fully attached. Final visual acuity (VA) was evaluated for each patient. The final visual acuity examination was carried out typically on a Snellen optotype, either without correction, with the patient's own spectacle correction or with correction according to the current values on the autorefractometer. The arithmetic average was used for the numerical expression of the attained results, and the numerical values were also expressed in percentages. Since the different groups were not compared with each other, no statistical test was necessary to analyze the results. RESULTS: In 150 (98.7%) of the 152 patients in the group, we achieved complete retinal reattachment, in 2 (1.3%) patients the retina remained detached, and we recorded anatomical failure of the treatment. Fifty (33%) patients achieved VA ≥ 4/8. CONCLUSION: In 133 (87.5%) patients, we are able to state anatomical success even without the presence of intraocular tamponade in the operated eye. These patients can be considered completely cured. 25G+ PPV has demonstrated its contribution to resolving RRD.

Comparison of effect of machine muteness to reduce noise anxiety vs regular settings on patient compliance during pan-retinal photocoagulation.

This Quasi Experimental study was conducted at Major Eye Clinic, Gujranwala, from January to December 2022, to study the effect of muting the sound of Argon Laser machine on patient compliance and the pain felt during pan-retinal photocoagulation (PRP). Eighty patients were included in the study with proliferative diabetic retinopathy (PDR), retinal breaks, lattice and myopic fundus degenerations for which PRP was performed. A total of 80 patients were enrolled, who were divided in two groups with 40 patients in each group. Group A patients received muted machine settings, while group B underwent regular PRP. The mean age was 54.6±3.4 years. Sixty-eight (85%) cases were of PDR, 4 (5%) of retinal breaks, 3 (3.75%) of lattice degenerations associated with breaks, and 5 (6.25%) of laser barrage. In group A, 28 (70%) patients had grade 1 and grade 2 pain score, while in group B, 26 (65%) had grade 3 and grade 4 pain score. It was concluded that by eliminating machine sound, noise anxiety can be greatly reduced ensuring better patient cooperation.

Retinal Oxygenation With Conventional 100-ms Versus Short-Pulse Pan-Retinal Laser Photocoagulation.

BACKGROUND AND OBJECTIVE: Conventional (100 ms) pan-retinal photocoagulation (PRP) laser burns are larger than short-pulse (10 ms to 20 ms) PRP burns. This study investigates the effect of PRP burns of different sizes on retinal oxygenation. METHOD: A mathematical model using COMSOL Multiphysics 6 was used to create a three-dimensional abstraction of the coupled biology of the choroid, photoreceptor, and retinal tissues. Laser burn sizes were varied in the model, specifically considering burn diameters of 500 µm, 250 µm, and 125 µm, while keeping the total burn area constant. RESULTS: Total increase in retinal oxygenation was the same for different burn sizes, but the oxygen distribution differed. Smaller burns resulted in a more even lateral oxygen distribution but with reduced penetration into the inner retina. CONCLUSIONS: Conventional and short-pulse PRP may affect retinal oxygenation differently, even when total burn area is the same. Further investigation into optimum burn size and pattern is required. [Ophthalmic Surg Lasers Imaging Retina 2024;55:40-45.].

Aniseikonia and retinal morphological changes in eyes undergoing macular hole surgery.

Even after idiopathic macular hole (MH) surgery and with successful closure of MH, aniseikonia is a common postoperative symptom. We investigated the correlation of MH diameter, retinal displacement and retinal layer thicknesses with aniseikonia in 41 eyes of 41 patients undergoing MH surgery with internal limiting membrane peeling. Aniseikonia was measured with the New Aniseikonia Test. Retinal displacement (RD%) was defined as change of retinal distance between the temporal margin of the optic papilla and the intersection of the retinal vessels. Changes of thicknesses of the inner nuclear layer (INL%) and the outer retinal layer (OR%) were calculated. Aniseikonia improved postoperatively. Preoperative aniseikonia and their improvement at 6 months correlated with MH diameters (P = 0.004-0.046). Improvement of aniseikonia correlated with temporal RD% (P = 0.002-0.012). Improvement of vertical aniseikonia correlated with INL% at 2 weeks and with the nasal OR% at 1, 3, and 6 months (P = < 0.001-0.028). MH diameter and age were significant predictors for improvement of aniseikonia. The greater the temporal retina displacement, and the thinner the postoperative INL and OR, the greater the improvement of aniseikonia. MH diameter and age are strong predictors for improvement of aniseikonia after MH surgery.

Honeycomb-Patterned Graphene Microelectrodes: A Promising Approach for Safe and Effective Retinal Stimulation Based on Electro-Thermo-Mechanical Modeling and Simulation.

The main objective of the present study is to use graphene as electrode neural interface material to design novel microelectrodes topology for retinal prosthesis and investigate device operation safety based on the computational framework. The study's first part establishes the electrode material selection based on electrochemical impedance and the equivalent circuit model. The second part of the study is modeling at the microelectrode-tissue level to investigate the potential distribution, generated resistive heat dissipation, and thermally induced stress in the tissue due to electrical stimulation. The formulation of Joule heating and thermal expansion between microelectrode-tissue-interface employing finite element method modeling is based on the three coupled equations, specifically Ohm's law, Navier's equation, and Fourier equation. Electrochemical simulation results of electrode material reveal that single-layer and few-layer graphene-based microelectrode has a specific impedance in the range of 0.02- [Formula: see text], comparable to platinum counterparts. The microelectrode of [Formula: see text] size can stimulate retinal tissue with a threshold current in the range of 8.7- [Formula: see text]. Such stimulation with the observed microelectrode size indicates that both microelectrodes and retinal tissue stay structurally intact, and the device is thermally and mechanically stable, functioning within the safety limit. The results reveal the viability of high-density graphene-based microelectrodes for improved interface as stimulating electrodes to acquire higher visual acuity. Furthermore, the novel microelectrodes design configuration in the honeycomb pattern gives the retinal tissue non-invasive heating and minimal stress upon electrical stimulation. Thus, it paves the path to designing a graphene-based microelectrode array for retinal prosthesis for further in vitro or in vivo studies.

Relaxing radial retinal incisions for the treatment of persistent macular holes.

PURPOSE: Various surgical techniques have been described for managing persistent macular holes after an unsuccessful vitrectomy with internal limiting membrane (ILM) peeling. However, the closure and functional improvement rates after these procedures are limited. Therefore, the aim of this study was to evaluate the usefulness of radial retinal incisions (retinotomies) in eyes with persistent large macula holes despite previous vitrectomy with ILM peeling. DESIGN: In a retrospective case series, closure rate and best-corrected visual acuity (BCVA) were evaluated in eyes with persistent macular holes after an unsuccessful vitrectomy that included posterior vitreous detachment and ILM peeling. SUBJECTS: 22 eyes of 22 patients (10 men and 12 women) underwent re-vitrectomy with radial retinal incisions. All the patients had undergone an unsuccessful surgery before. METHODS: Small-incision re-vitrectomy with radial retinal incisions (retinotomies) and air tamponade was performed. MAIN OUTCOME MEASUREMENTS: For all eyes, high-definition SD-OCT scans (SD-OCT Spectralis, Heidelberg Engineering GmbH, Germany) of the macula were routinely performed before surgery; 1 week and 1 month after surgery; and at final follow-up. Additionally, age, gender, axial length, macular hole diameter, biomicroscopic fundus evaluation and best-corrected visual acuity (BCVA) in logMAR and Snellen at baseline, 1 and 4 months after operation, and at the final follow-up visit were analyzed. RESULTS: The mean baseline macular hole diameter was 668.5 ± 226.8 µm. At the final examination, 16 (72.72%) of the 22 macula holes were closed. Visual acuity increased in 17 eyes, was stable in 3 eyes, and decreased in 2 eyes owing to central retinal atrophy in both. The mean BCVA increased from logMAR 1.04 ± 0.29 at baseline to 0.57 ± 0.31 (Snellen 0.11 ± 0.05 to 0.33 ± 0.18). In all successful cases, macula hole closure was attained after 3 days, and none of the eyes showed macula hole recurrence. CONCLUSION: The results of this limited case series suggest that radial retinal incisions of the rim in persistent macula holes after initial surgery with ILM peeling increase the success rate of macula hole closure and results in a relevant increase in BCVA. However, as the number of eyes included in this series is limited, the results must be confirmed in a study with a larger sample size.

Correlation between Anatomical and Functional Outcomes in Patients with Idiopathic Epiretinal Membrane after Vitrectomy.

BACKGROUND: Idiopathic epiretinal membrane (iERM) is a common disorder of the vitreomacular interface characterized by decreased visual acuity and metamorphopsia. This study aimed to analyze the association between the anatomical change of the retina and functional outcomes in iERM patients so as to derive the prognostic factors of visual acuity (VA) and metamorphopsia. METHODS: Forty-five patients (one eye per patient; 45 eyes in total) who underwent pars plana vitrectomy and membrane peeling for iERM by a single surgeon were enrolled in this retrospective study. The results on best-corrected visual acuity (BCVA) and metamorphopsia as well as retinal images were obtained before the surgery and 1, 3, 6 months after the surgery. The BCVA and retinal microstructure, including central retinal thickness (CRT), ganglion cell layer (GCL) thickness, inner nuclear layer (INL) and outer nuclear layer + outer plexiform layer (ONL+OPL), and continuity of photoreceptor inner/outer segment (IS/OS) junction before and after iERM surgery were compared using paired samples t-test (continuous variables) or Chi-square test (categorical variables). Multiple regression analysis was carried out to explore the association among BCVA, M-score, and the parameters derived from optical coherence tomography. RESULTS: Compared with preoperative data, a significant improvement in BCVA was observed 1, 3, and 6 months postoperatively (t = 5.37, p < 0.0001; t = 7.29, p < 0.0001; t = 6.44, p < 0.0001 for 1, 3, and 6 months postoperatively, respectively), whereas the M-score only decreased significantly 3 and 6 months after the surgery (t = 2.36, p = 0.02; t = 5.00, p < 0.0001, respectively). In comparison with the baseline, the CRT, INL, and ONL+OPL thickness showed a significant decrease at each postoperative follow-up time, and GCL thickness (t = 3.86, p = 0.0002) and IS/OS disruption ratio (χ2 = 4.86, p = 0.027) were markedly reduced only 6 months postoperatively. Six-month postoperative BCVA was considerably associated with preoperative CRT and ONL+OPL thickness, as well as postoperative CRT, ONL+OPL thickness, and severity of IS/OS disruption. Moreover, the M-score after surgery was markedly correlated with both the preoperative and postoperative INL and CRT thickness. CONCLUSIONS: Both VA and M-score in iERM patients were significantly improved after vitrectomy. Pre- and post-operative CRT was significantly associated with both postoperative BCVA and M-score. Besides, pre- and post-operative INL thickness was correlated to postoperative metamorphopsia, and postoperative BCVA was associated with postoperative ONL+OPL thickness and IS/OS integrity.

A Literary Pediatric Retina Fellowship With Michael T. Trese, MD.

Michael T. Trese, MD (1946-2022), a vitreoretinal surgeon, made significant contributions to the field of retina. Although most known for his work in pediatric retina surgery, he was a pioneer in areas such as medical retina, translational research, and telemedicine. This article reviews his major contributions to spread his knowledge more widely to vitreoretinal trainees and specialists. We discuss six areas where Trese made a lasting impact: lens-sparing vitrectomy, familial exudative vitreoretinopathy, congenital X-linked retinoschisis, autologous plasmin enzyme, regenerative medicine, and telemedicine. [Ophthalmic Surg Lasers Imaging Retina 2023;54:701-712.].

[Primary vitrectomy in the treatment of retinopathy of prematurity with unfavorable progression]. / Pervichnaya vitrektomiya v lechenii retinopatii nedonoshennykh neblagopriyatnogo tipa techeniya.

PURPOSE: The study aims to determine the indications and evaluate the results of primary vitrectomy in unfavorable progression of stage III active retinopathy of prematurity (ROP). MATERIAL AND METHODS: The control group consisted of 17 patients (28 eyes) with unfavorable progression of stage III ROP, who had the disease progress after coagulation of the avascular retina and underwent the second stage of treatment - vitrectomy. The main group consisted of 5 patients (10 eyes) with unfavorable progression of stage III ROP, who underwent primary vitrectomy. Gestational age at birth was 24-30 weeks, body weight ranged from 680 to 1250 g. According to spectral optical coherence tomography (SOCT) and OCT angiography (OCT-A), the initial state of the retina and vitreoretinal interface in patients of the main and control groups were identical. RESULTS: A retrospective analysis of control patients, according to SOCT and OCT-A data, showed the spread of neovascularization beyond the retinal plane, its interaction with the posterior hyaloid membrane and vitreous body structures in the early stages of the disease, traction changes in the underlying retina, areas of retinoschisis, as well as thickening of the posterior hyaloid membrane. The tactics of treating patients with unfavorable progression of stage III ROP has changed since 2020. Primary vitrectomy was performed in case the signs listed above were identified. The transition of the disease to the inactive stage was recorded in all cases one month after primary vitrectomy. After one year the pathological process did not reactivate in any of the cases, and no pathological changes were found in the projection of the former proliferation ridge. CONCLUSIONS: Extraretinal retinovitreal neovascularization, according to multimodal preoperative diagnostics, indicates the need for vitreoretinal surgery as a pathogenetically substantiated method of treatment for unfavorable progression of stage III active ROP.

Obtaining High-Quality Cryosections of Whole Rabbit Eye.

This protocol describes how to obtain high-quality retinal cryosections in larger animals, such as rabbits. After enucleation, the eye is briefly immersed in the fixative. Then, the cornea and iris are removed and the eye is left overnight for additional fixation at 4 °C. Following fixation, the lens is removed. The eye is then placed in a cryomold and filled with an embedding medium. By removing the lens, the embedding medium has better access to the vitreous and leads to better retinal stability. Importantly, the eye should be incubated in embedding medium overnight to allow complete infiltration throughout the vitreous. Following overnight incubation, the eye is frozen on dry ice and sectioned. Whole retinal sections may be obtained for use in immunohistochemistry. Standard staining protocols may be utilized to study the localization of antigens within the retinal tissue. Adherence to this protocol results in high-quality retinal cryosections that may be used in any experiment utilizing immunohistochemistry.

Deep learning-based prediction of the retinal structural alterations after epiretinal membrane surgery.

To generate and evaluate synthesized postoperative OCT images of epiretinal membrane (ERM) based on preoperative OCT images using deep learning methodology. This study included a total 500 pairs of preoperative and postoperative optical coherence tomography (OCT) images for training a neural network. 60 preoperative OCT images were used to test the neural networks performance, and the corresponding postoperative OCT images were used to evaluate the synthesized images in terms of structural similarity index measure (SSIM). The SSIM was used to quantify how similar the synthesized postoperative OCT image was to the actual postoperative OCT image. The Pix2Pix GAN model was used to generate synthesized postoperative OCT images. Total 60 synthesized OCT images were generated with training values at 800 epochs. The mean SSIM of synthesized postoperative OCT to the actual postoperative OCT was 0.913. Pix2Pix GAN model has a possibility to generate predictive postoperative OCT images following ERM removal surgery.