Intraocular Pressure Telemetry for Managing Glaucoma during the COVID-19 Pandemic

PURPOSE

To evaluate in glaucoma patients the feasibility and use of remote monitoring of intraocular pressure (IOP) with an implanted telemetry sensor during the coronavirus disease 2019 (COVID-19) lockdown.

DESIGN

Cross-sectional study.

PARTICIPANTS

Patients previously implanted with a telemetric IOP sensor (Eyemate; Implandata GmbH) were included.

METHODS

Intraocular pressure measurements acquired by the patients during the lockdown were collected by physicians who were located remotely. A questionnaire was sent to 10 participating study centers to evaluate the clinical impact of remote monitoring of IOP via the IOP sensor system.

MAIN OUTCOME MEASURES

Number of patients who obtained home IOP measurements.

RESULTS

Data were available from all centers and from 37 eyes of 37 patients (16 patients with a sulcus-based sensor and 21 patients with a suprachoroidal sensor). Thirty-four patients obtained IOP measurements during the lockdown. Mean age of the patients was 69.3 ± 9.6 years, and 48.6% were women. A total of 8415 IOP measurements from 370 measurement days were obtained. Based on remote IOP measurements, treatment was changed in 5 patients. In another 5 patients, treatment change was considered when physicians received the IOP measurements after the lockdown. Nine of the 10 study centers judged remote IOP measurements to have a clinical impact.

CONCLUSIONS

These results show the feasibility of patient-acquired measurement of IOP in conjunction with remote IOP monitoring by physicians with an implantable sensor. The data obtained impacted clinical decision making, including adjustment of ocular hypotensive therapy and avoiding unnecessary office visits during the COVID-19 pandemic.

Alginate- and Hyaluronic Acid-Based Hydrogels as Vitreous Substitutes: An In Vitro Evaluation

Purpose

To study alginate- and hyaluronic acid–based hydrogels in vitro as vitreous substitutes.

Methods

Biopolymeric hydrogels based on high-molecular alginate (0.5% and 1.0%) and hyaluronic acid (1.0% and Healaflow) were compared with extracted human vitreous bodies and silicone oil (SIL-5000) regarding their optical properties (refractive index, transmission) and viscoelastic characteristics (storage modulus G′, loss modulus G″). The cytotoxic (metabolic activity, apoptosis) and antiproliferative profiles were determined using cultured human fibroblasts, ARPE-19, and photoreceptor cells. The hydrogel systems were applied to human fetal retinal pigment epithelial cells cultured for two months until maximum transepithelial electrical resistance (TEER) to investigate the effect of the gel matrices on tight junctions using TEER measurements and immunostainings against the tight junction protein ZO-1.

Results

Tested alginate- and hyaluronic acid–based hydrogels resembled the natural refractive index of human vitreous bodies (1.3356–1.3360) in contrast to SIL-5000 (1.4034) and showed high optical transparency (>90%) within the visible light region. The biopolymeric hydrogels exhibited viscoelastic properties similar to juvenile vitreous bodies with G′>G″ adjustable via different gelation times, contrary to SIL-5000 (G′<G″). The metabolic activity, apoptosis and tight junctions of all tested ocular cells were unaffected by the alginate- and hyaluronic acid–based vitreous substitutes.

Conclusions

The present in vitro study demonstrates good optical, viscoelastic, and biocompatible properties of alginate- and hyaluronic acid–based hydrogels required for their use as vitreous substitutes.

Translational Relevance

Biopolymer-based hydrogels represent a promising vitreous replacement strategy to treat vitreoretinal diseases.

Assessment of Macular Function Following Internal Limiting Membrane Peeling With ILM Blue®

Purpose To evaluate clinical outcome after surgery of idiopathic epiretinal membranes (ERM) with internal limiting membrane (ILM) peeling using a commercial combination of Brilliant blue G (BBG, 0.25 mg/ml) with 4% polyethylene glycol (PEG). Methods It was a prospective, single-center study. Macular surgery was performed due to ERM (n = 18) by two experienced surgeons. Exclusion criteria were secondary ERM, previous retinal surgery and pharmacological treatment. Best-corrected visual acuity (BCVA), optical coherence tomography (OCT), and multifocal ERG (RETIscan) were assessed at baseline and three months after surgery. Results The BCVA improved from baseline 0.4 ± 0.13 logMAR to 0.3 ± 0.2 logMAR after three months (p > 0.05). The mean central foveal thickness was reduced from 407 ± 85 μm to 366 ± 56 μm after three months (p > 0.05). At baseline, the mean P1 amplitude (nV/deg²) was 53.5 ± 32.1 in ring 1 and 35.9 ± 20.1 in ring 2. Three months after surgery the mean P1 amplitude was comparable with 57.2 ± 16.3 in ring 1 and 38.0 ± 11.7 in ring 2 compared with the initial situation (p = 0.22 and p = 0.3, respectively). Conclusion BBG with 4% PEG can be used for ILM peeling in patients with idiopathic epiretinal membranes without any sign of short-term toxicity.

Wireless retina implant with optical energy supply

We present the first results of work towards a foil-based epiretinal prosthesis that can stimulate retinal cells. The prosthesis receives trigger signals and energy in the form of high intensity infrared radiation. Array-like silicon photodiodes with attached thin film electrodes convert the received infrared light into electrical stimulation signals, which are intended to stimulate ganglion cells. The photodiodes are arranged like stones in a mosaic on an only 10 µm thin and thus flexible polymer foil. Like this, the prosthesis can adapt to the curved shape of the eye and will have close contact with the retina.

The photodiode array is fabricated on silicon wafers. Etched trenches guarantee the electrical separation between the individual photodiodes and pixels. Spectral sensitivities of backside-illuminated photodiodes were measured for wafers thinned to different thicknesses. The thin polymer foil is realized by spin coating polyimide on the photodiode array followed by imidization. Via holes are etched into the polyimide film for contacting the pads of the photodiodes. First spin coating tests were performed using silicon wafers without photodiodes but with metal pads and with etched trenches to simulate the gap between individual photodiodes.

Although the thickness of the spin-coated polyimide layer was very inhomogeneous, we succeeded in realizing vias for connecting contact pads by thin film gold tracks crossing deep trenches. The realized via holes had inclined sidewalls as desired. Electrical measurements showed sufficient electrical contact between two connected pads.

[Value of Intraoperative OCT in Retinal Surgery. Part 2: Contra]

One of the most controversial discussions in retinal surgery is currently being held about the importance of intraoperative OCT (iOCT). The background is the desire to combine the 2-dimensional fundus view of the surgeon with the layered depth information of OCT to achieve a 4-dimensional "augmented reality" (3-D plus change over time). This should help to visualise fine structures, which have been hidden from the surgeon's view. Therefore, retinal surgery seems to be predestined for the use of iOCT. The great hope is that a dynamic live 3-D image with real-time feedback will provide the surgeon with additional information and improve safety. Although fascinating at the first glance, in the surgical routine, however, iOCT technology is disappointing, especially in macular surgery. It rarely provides substantial information that would not be obtainable without iOCT or that would not be available in much better quality through preoperative diagnostic testing. Only some special indications remain, particularly related to subretinal surgery.

Canaloplasty with Suprachoroidal Drainage in Patients with Pseudoexfoliation Glaucoma - Four Years Results

Purpose: To evaluate the long-term efficacy and safety of the modified canaloplasty technique with additional suprachoroidal drainage in patients with pseudoexfoliation glaucoma. Methods: This retrospective clinical trial included 131 patients with pseudoexfoliation glaucoma who underwent canaloplasty with suprachoroidal drainage (scD). One hundred and eleven of 131 patients underwent the follow-up examination after 48 months. Primary endpoints were the pressure-lowering and drug-sparing effect as well as the success rates. Secondary endpoints were intra- and postoperative complications and the occurrence of secondary surgical interventions. Results: The IOP was reduced by 45.8% after 12 months (from baseline 23.4 ± 5.1 mmHg to 12.7 ± 2.2 mmHg) and by 45.1% after four years (12.8 ± 2.2 mmHg) (p < .001). The mean number of IOP-lowering medication decreased significantly from 3.4 at baseline to 0.6 after 12 months and to 1.0 after four years. The IOP-reducing effect was even stronger in those cases in whom canaloplasty+ scD was combined with cataract surgery (49.4% after 12 months and 47.6% after four years). No serious complications were observed. Conclusions: The modified surgery technique of canaloplasty with suprachoroidal drainage is a safe and effective way of reducing IOP in patients with pseudoexfoliation glaucoma.

Comparison of preloaded grafts for Descemet membrane endothelial keratoplasty (DMEK) in a novel preloaded transport cartridge compared to conventional precut grafts

To determine the safety and graft quality of eye bank precut and preloaded grafts for Descemet membrane endothelial keratoplasty (DMEK) after storage and shipping in a novel preloaded transport cartridge compared to precut grafts in a conventional viewing chamber. In this laboratory proof-of-concept study, 29 human donor corneas that were unsuitable for transplantation with a mean endothelial cell density of 1948 ± 260 cells/mm2 were prepared using liquid bubble technique for producing precut lamellar grafts. The grafts were either preloaded into novel transport cartridge (n = 16) or transferred into conventional Krolman viewing chamber (control, n = 13). Grafts were stored for 24 or 48 h in dextran-containing medium at room temperature and subjected to a shipping simulation. Endothelial cell loss (ECL) and morphology were determined at different steps. Endothelial cell viability staining was performed with calcein dye. Mean ECL in the preloaded transport cartridge was 0.7% ± 1.2% after 24 h and 3.4% ± 1.2% (p = 0.006) after 48 h storage and injection. In the control group the ECL was mean 1.6% ± 2.7% after 24 h compared to 3.7% ± 0.9% (p = 0.042) after 48 h. The slightly higher endothelial cell loss in the viewing chamber group after 48 h was not statistically significant compared to the preloaded transport cartridge (p = 0.8). Calcein staining was comparably low in all groups and correlated with the low ECL in both groups. DMEK grafts can be preloaded into a novel transport cartridge using a "no touch" technique, stored and shipped for up to 2 days in dextran-containing medium without significant ECL.

Predictive factors for the IOP reduction in phacocanaloplasty with suprachoroidal drainage

PURPOSE

Although the pressure-reducing effect of cataract surgery alone is not very high, it is often cited in the literature. Some authors describe predictive factors correlated with the IOP (intraocular pressure) reduction: in particular noteworthy are age, axial length, preoperative pressure level and the ratio of preoperative pressure/anterior chamber depth. The aim of this study was to determine the applicability of these predictive factors to phacocanaloplasty with suprachoroidal drainage. Setting Eye Clinic Sulzbach Germany.

DESIGN

Retrospective study with a 12-month follow-up, including patients that underwent phacocanaloplasty with suprachoroidal drainage between 2012 and 2014.

METHODS

Preoperatively, baseline information was collected (including age, diagnosis, medication), and the patients underwent a basic examination and optical biometry. To investigate the relationship between preoperative parameters and the IOP reduction, Pearson's correlation analysis and linear regression were used. Patients with missing data pre- or postoperatively were excluded from the analysis.

RESULTS

The study comprised 89 patients. Mean preoperative IOP was 23.0 ± 5.3 mmHg with 4.0 different antiglaucomatous eye drops. After 12 months, IOP was reduced to 12.1 ± 1.4 mmHg with a median medication of 0.0. The preoperative IOP and the ratio of preoperative IOP/anterior chamber depth were identified as predictive factors. There was no influence of axial length and anterior chamber depth.

CONCLUSION

Unlike in cataract surgery, anterior chamber depth and axial length have no influence on the pressure reduction caused by phacocanaloplasty. However, a strong predictive factor is the preoperative pressure level. The higher the preoperative IOP, the greater the postoperative pressure reduction.

Combined Administration of Preoperative Intravitreal and Intraoperative Subretinal Recombinant Tissue Plasminogen Activator in Acute Hemorrhagic Age-related Macular Degeneration

Purpose

To evaluate the efficacy of combining pre-operative intravitreal administration of recombinant tissue plasminogen activator (rTPA) followed by 23G pars plana vitrectomy with the subretinal administration of rTPA in the management of acute submacular hemorrhage (SMH) secondary to neovascular age-related macular degeneration (AMD).

Methods

This is a single-center case series report that included 14 patients with SMH secondary to neovascular AMD. All of them received preoperative intravitreal injection of 0.05 ml (50 µg) rTPA, followed on the next day by 23G pars plana vitrectomy with subretinal 0.1 ml (10 µg) rTPA administration and air tamponade.

Results

There was a significant (p=0.01) overall improvement in the visual acuity post-treatment (from 1.4±0.5 log MAR to 0.9±0.4). The mean overall change in the visual acuity post-treatment was 0.5±0.3 log MAR (mean % change=31.7±15.1). There was a significant (p=0.03) overall reduction in the central macular thickness post-treatment (896±608.1 µm to 497.2±196.0 µm). The mean overall change in the central macular thickness post-treatment was 398.8±458.1 µm (mean % change=38.1±18.1).

Conclusion

Combined treatment of 24 hours of preoperative administration of intravitreal rTPA followed the next day by vitrectomy and the administration of subretinal rTPA with air tamponade appeared to be effective as a prompt intervention in managing acute SMH secondary to neovascular AMD. However, similar studies with larger sample size and a control comparative group are warranted to further confirm these findings.

ADVERSE EVENTS OF THE ARGUS II RETINAL PROSTHESIS: Incidence, Causes, and Best Practices for Managing and Preventing Conjunctival Erosion

PURPOSE

To analyze and provide an overview of the incidence, management, and prevention of conjunctival erosion in Argus II clinical trial subjects and postapproval patients.

METHODS

This retrospective analysis followed the results of 274 patients treated with the Argus II Retinal Prosthesis System between June 2007 and November 2017, including 30 subjects from the US and European clinical trials, and 244 patients in the postapproval phase. Results were gathered for incidence of a serious adverse event, incidence of conjunctival erosion, occurrence sites, rates of erosion, and erosion timing.

RESULTS

Overall, 60% of subjects in the clinical trial subjects versus 83% of patients in the postapproval phase did not experience device- or surgery-related serious adverse events. In the postapproval phase, conjunctival erosion had an incidence rate of 6.2% over 5 years and 11 months. In 55% of conjunctival erosion cases, erosion occurred in the inferotemporal quadrant, 25% in the superotemporal quadrant, and 20% in both. Sixty percent of the erosion events occurred in the first 15 months after implantation, and 85% within the first 2.5 years.

CONCLUSION

Reducing occurrence of conjunctival erosion in patients with the Argus II Retinal Prosthesis requires identification and minimization of risk factors before and during implantation. Implementing inverted sutures at the implant tabs, use of graft material at these locations as well as Mersilene rather than nylon sutures, and accurate Tenon's and conjunctiva closure are recommended for consideration in all patients.

Impact of Patient Interface Diameter and Vacuum Level on Suction Stability Using a Flat Applanating Interface for Femtosecond Laser-Assisted LASIK

PURPOSE

To investigate the impact of different patient interface (PI) diameters and different vacuum levels on the suction stability during vacuum application for femtosecond laser-assisted LASIK.

METHODS

Break-away forces as a marker for suction stability were measured by an automated test bench set-up. The test bench was based on a customized stamp connected to a digital load cell. Three flat applanating PI with different diameters (8.5, 9.5 and 10.0 mm) and four different vacuum levels (500, 600, 700 and 800 mbar) were investigated using the FEMTO LDV Z8 (Ziemer Ophthalmic Systems AG, Switzerland).

RESULTS

Mean break-away force was 5.23N (±0.99N) using the 8.5 mm PI and 500 mbar vacuum, 8.18N (±1.39N) using the 8.5 mm PI and 800 mbar, 3.37N (±0.56N) using the 10.0 mm PI and 500 mbar, and 6.14N (±0.68N) using the 10.0 mm PI and 800 mbar vacuum (p < .001; CI95%). Increasing the PI diameter from 8.5 to 10.0 mm resulted in a 28.89% (+1.97 ± 1.02N) lower break-away force (p < .001) when using default vacuum settings (700 mbar) compared to increasing vacuum from 500 to 800 mbar, which resulted in a 60.37% (+1.95 ± 1.40N) higher mean break away force (p < .001).

CONCLUSION

The vacuum level and the diameter of the PI showed significant impact on suction stability measured as break-away force during flat applanating docking for corneal and refractive surgery. Break-away forces were inversely related to the PI diameter and directly to the vacuum level. Increasing the PI diameter by one step or reducing vacuum by 100 mbar resulted in a comparable decrease of break-away forces. Therefore, the surgeon could potentially maintain stabile suction by increasing vacuum when choosing a larger PI diameter to obtain a larger treatment zone. Furthermore, reduction of the PI diameter and/or increasing vacuum could help improving suction stability in situations of poor suction and in situations with increased risk of suction loss during LASIK.

Significant differences between specular microscopy and corneal bank endothelial cell counts - a pilot study

BACKGROUND

It was shown recently that endothelial cell count performed by cornea banks overestimates the real number of endothelial cells. The aim of this study was to investigate the internal quality of preclinical ECD in human donor corneas using two widely used methods for endothelial cell counting, transmitted light microscopy used in organ culture tissue bank and clinically used specular microscopy.

METHODS

Twenty human donor corneas that could not be transplanted were included in this analysis. Differences in evaluating endothelial cell density (ECD) and hexagonal endothelial cell ratio (HEX) between clinical specular microscopy (CSM) and corneal bank transmitted light microscope (CBLM) were evaluated as well as differences between automated and manual cell counts.

RESULTS

Automated CBLM showed a higher ECD of 31.85% compared to automated CSM, while manual CBLM counting is 10.51% higher compared to manual CSM (p < 0.01). Further, higher average ECD values result in a higher difference between CSM and CBLM measurements. The manual CBLM ECDs were significantly higher compared to automated derived ECD from CSM (p < 0.01). However, no systematic bias can be detected when comparing the differences of the measurements with the average ECD measurements of both methods.

CONCLUSION

This preclinical pilot study confirmed a significant higher ECD using transmitted light microscopy in organ culture compared to clinical specular microscopy. This indicates that the early rapid decrease of EC universally observed after surgery might be partly artefactual.

Analysis of different types of anesthesia in descemet membrane endothelial keratoplasty

PURPOSE

The purpose of this study is to compare the safety and clinical results of descemet membrane endothelial keratoplasty (DMEK) in topical, peribulbar or general anesthesia.

METHODS

This is a retrospective, post hoc matched study of 120 patients having received DMEK surgery with different types of anesthesia (n = 40 topical, n = 40 peribulbar, n = 40 general anesthesia). Endpoint criteria were intraoperative complications, endothelial cell count, central corneal thickness and graft rejection rate, rebubbling rate and best-corrected visual acuity after 1, 3 and 6 months.

RESULTS

The group with topical anesthesia showed more often intraoperative difficulties such as vitreous pressure (p < 0.05), difficult graft unfolding (p = 0.14) and patient restlessness (p = 0.07). However, all three groups achieved comparable functional visual results after 6 months (p = 0.96).

CONCLUSION

DMEK in topical anesthesia is feasible and shows comparable final visual results but should be restricted to selected cooperative patients and performed by experienced surgeons due to possible higher intraoperative challenges.

[Toxicity of heavy liquids]

BACKGROUND

Acute toxicity of perfluorocarbon liquids (PFCL) is a relevant problem in retinal surgery due to impurities in the medicinal product.

OBJECTIVE

This article gives an overview of the current problems, possible explanations, interactions with other medicinal products and approaches to improved patient safety.

RESULTS

Toxicity is caused by impurities in the raw material but can also be caused by interactions with other medicinal products or drugs. The current test procedures do not ideally represent the ophthalmological application but there are promising activities to set the course for the future.

CONCLUSION

The use of PFCL in retinal surgery is generally considered safe. Users should pay attention to the quality of medicinal products.

One-Year Safety and Performance Assessment of the Argus II Retinal Prosthesis: A Postapproval Study

Importance

The Argus II Retinal Prosthesis System is indicated for patients with vision loss due to severe to profound outer retinal degeneration, a group with few treatment options.

Objectives

To collect postapproval safety and visual function data for the Argus II.

Design, Setting, and Participants

Multicenter, postapproval clinical trial conducted at 9 sites in Germany and Italy. Data were collected from December 2, 2011, to September 30, 2017, and patients were followed-up for 12 months or longer. Patients were 25 years or older with severe to profound outer retinal degeneration, some residual light perception or the ability of the retina to respond to electrical stimulation, and a history of useful form vision and were already planning to undergo Argus II implantation.

Main Outcomes and Measures

The primary end point of this study was the nature and rate of adverse events. Secondary end points included 3 visual function tests: square localization (SL), direction of motion, and grating visual acuity (GVA).

Results

Forty-seven patients were followed for 12 months or longer after implant. Mean (SD) age was 56 (12) years, 37 (79%) had retinitis pigmentosa, and 27 (57%) were male. Through the first 12 months postimplantation, 23 patients (49%) experienced 51 nonserious adverse events and 12 (26%) experienced 13 serious adverse events (SAEs), 9 of which were judged to be related to the Argus II, and 4 of which were judged to be related to the procedure. The most common SAE was conjunctival erosion, reported in 4 patients. No significance testing was done for group analysis for the SL or direction-of-motion tests. When averaged across the group, patients' accuracy on the SL test, but not on the direction-of-motion test, appeared better when the Argus II was on than when it was switched off. For GVA, more patients at each point in time achieved the 2.9 GVA cutoff in the implanted eye when the Argus II was on compared with it switched off.

Conclusions and Relevance

Safety and visual function outcomes in this clinical practice setting cohort of patients with Argus II implants were consistent with previously reported results. Longer follow-up of these patients and data from additional patients are required to better outline the risks and benefits of this approach to addressing blindness secondary to severe-to-profound outer retinal degeneration.

Trial Registration

ClinicalTrials.gov identifier: NCT01490827.