[First clinical results with the PAUL® Glaucoma Implant at the University Eye Hospital Bonn]

BACKGROUND

Glaucoma drainage devices (GDD) are an invasive procedure for the treatment of glaucoma. The PAUL® Glaucoma Implant (PGI) has been developed as a new, innovative therapeutic procedure. The PGI differs from previous GDD with regard to the smaller size of the drainage tube.

OBJECTIVE

This study analyses 6‑months results of the PGI in terms of effectiveness and safety.

METHODS

A database of patients treated with the PGI at the University Eye Hospital Bonn was created and continuously updated based on follow-up controls. Statistical analysis was performed using SPSS Statistics for Windows (IBM Corp., Armonk, NY, USA).

RESULTS

A total of 53 eyes of the first 51 consecutive patients treated with the PGI were included in this study. Mean intraocular pressure was 26.62 mmHg (7-48 mmHg) preoperatively and reduced to 12.20 mmHg (3-22 mmHg) after 6 months. Local pressure-lowering therapy was reduced from 3.37 agents preoperatively to 0.30 agents after 6 months. The complication rate was low; only 3 patients (5.8%) had persistent hypotony. In 16 patients, the intraluminal prolene stent was removed in the postoperative course after an average of 2.9 months. Thereafter, these patients experienced a reduction of intraocular pressure from 22.21 to 11.07 mmHg.

CONCLUSION

The PAUL® Glaucoma Implant is a safe treatment modality that can successfully reduce intraocular pressure to a low level and reduce pressure-lowering local therapy. It has a low complication rate, particularly regarding postoperative hypotony.

Ranibizumab in retinopathy of prematurity - one-year follow-up of ophthalmic outcomes and two-year follow-up of neurodevelopmental outcomes from the CARE-ROP study

Purpose:

The primary endpoint results from the comparing alternative ranibizumab dosages for safety and effcacy in retinopathy of prematurity (CARE-ROP) core study identified ranibizumab as an effective treatment to control acute retinopathy of prematurity (ROP). This study reports the 1- and 2-year follow-up data focusing on long-term functional outcomes and safety.

Methods:

The CARE-ROP trial compared 0.12 mg versus 0.20 mg ranibizumab in 20 infants with ROP in a multicentric, prospective, randomized, double-blind, controlled study design. Sixteen patients entered the follow-up period. An ophthalmologic assessment at one year postbaseline was acquired from all 16 patients and a neurodevelopmental assessment at two years postbaseline was acquired from 15 patients.

Results:

Fifteen of 16 infants were able to fixate and follow moving objects at one year postbaseline treatment. One child progressed to stage 5 ROP bilaterally between the end of the core study and the 1-year follow-up (first seen at PMA 75 weeks). Mean spherical equivalents were −1.9 diopters (D) and −0.75 D in the 0.12 mg and the 0.20 mg treatment arms. Strabismus was present in seven and nystagmus in five out of 16 infants. Mental development scores were within normal limits in six out of ten patients with available data. No statistically significant difference was observed between the two treatment arms.

Conclusion:

Neurodevelopmental and functional ocular outcomes 1 and 2 years after treatment with ranibizumab are reassuring regarding long-term safety. Late reactivation of ROP, however, represents a challenge during the follow-up phase and it is of utmost importance that regular follow-ups are maintained.

Silicone oil tamponade for persistent macular holes

BACKGROUND

A variety of treatment strategies have been proposed for macular holes that persist or recur after surgery, and the debate about the best re-treatment approach is ongoing. To allow for a comparison with alternative surgical therapies, we assessed the anatomical and functional outcome of a temporary tamponade with conventional silicone oil in persistent or recurrent full-thickness macular holes.

METHODS

We retrospectively investigated consecutive patients with full-thickness macular holes that persisted or recurred following vitrectomy with internal limiting membrane peeling and gas tamponade. All patients received re-treatment by temporary tamponade of silicone oil and were allowed free postoperative positioning. Anatomical closure rate was assessed by optical coherence tomography, and change of best-corrected visual acuity (BCVA) was analyzed.

RESULTS

A total of 33 eyes of 33 consecutive patients were included. Macular hole closure following silicone oil tamponade was achieved in 30 of 33 eyes (90.9%). Median BCVA improved from 1.00 logMAR (interquartile range, 0.60-1.00) to 0.65 logMAR (0.49-1.00; p = 0.010) after silicone oil removal. In patients with macular hole closure, 61.3% exhibited functional improvement with median BCVA changing from 1.00 logMAR (0.70-1.00) to 0.60 logMAR (0.49-1.00; p = 0.0005). Mean minimal linear diameter of macular holes before primary surgery was 391.0 µm (±137.8; range 133-630), and 48.5% of macular holes were >400 µm in diameter.

CONCLUSIONS

Treatment of persistent or recurrent full-thickness macular holes by temporary conventional silicone oil tamponade without postoperative positioning results in a high closure rate and a significant mean improvement of visual acuity.

Survival and functionality of xeno-free human embryonic stem cell-derived retinal pigment epithelial cells on polyester substrate after transplantation in rabbits

PURPOSE

To study immunogenic properties of human embryonic stem cell-derived retinal pigment epithelium (hESC-RPE) and to evaluate subretinal xenotransplantation of hESC-RPE on porous polyethylene terephthalate (PET) in rabbits.

METHODS

Human ESC-RPE cells were characterized by morphology, transepithelial electrical resistance (TER), protein expression and photoreceptor outer segment phagocytosis in vitro. Expression of major histocompatibility complex (MHC) proteins was assessed in conventionally or xeno-free produced hESC-RPE ± interferon-gamma (IFN-γ) stimulation (n = 1). Xeno-free hESC-RPE on PET with TER < 200 Ω·cm²  > or PET alone were transplanted into 18 rabbits with short-term triamcinolone ± extended tacrolimus immunosuppression. Rabbits were monitored by spectral domain optical coherence tomography. After 4 weeks, the eyes were processed for histology and transmission electron microscopy.

RESULTS

Upon in vitro IFN-γ stimulation, xeno-free hESC-RPE expressed lower level of MHC-II proteins compared to the conventional cells. Outer nuclear layer (ONL) atrophy was observed over the graft in most cases 4 weeks post-transplantation. In 3/4 animals with high TER hESC-RPE, but only in 1/3 animals with low TER hESC-RPE, ONL atrophy was observed already within 1 week. Retinal cell infiltrations were more frequent in animals with high TER hESC-RPE. However, the difference was not statistically significant. In three animals, preservation of ONL was observed. Weekly intravitreal tacrolimus did not affect ONL preservation. In all animals, hESC-RPE cells survived for 4 weeks, but without tacrolimus, enlarged vacuoles accumulated in hESC-RPE (n = 1).

CONCLUSIONS

Xenografted xeno-free hESC-RPE monolayers can survive and retain some functionality for 4 weeks following short-term immunosuppression. The preliminary findings of this study suggest that further investigations to improve transplantation success of hESC-RPE xenografts in rabbits should be addressed especially toward the roles of hESC-RPE maturation stage and extended intravitreal immunosuppression.

A Step by Step Protocol for Subretinal Surgery in Rabbits

Age related macular degeneration (AMD), retinitis pigmentosa, and other RPE related diseases are the most common causes for irreversible loss of vision in adults in industrially developed countries. RPE transplantation appears to be a promising therapy, as it may replace dysfunctional RPE, restore its function, and thereby vision.

Here we describe a method for transplanting a cultured RPE monolayer on a scaffold into the subretinal space (SRS) of rabbits. After vitrectomy xenotransplants were delivered into the SRS using a custom made shooter consisting of a 20-gauge metallic nozzle with a polytetrafluoroethylene (PTFE) coated plunger. The current technique evolved in over 150 rabbit surgeries over 6 years. Post-operative follow-up can be obtained using non-invasive and repetitive in vivo imaging such as spectral domain optical coherence tomography (SD-OCT) followed by perfusion-fixed histology.

The method has well-defined steps for easy learning and high success rate. Rabbits are considered a large eye animal model useful in preclinical studies for clinical translation. In this context rabbits are a cost-efficient and perhaps convenient alternative to other large eye animal models.

Localized RPE Removal with a Novel Instrument Aided by Viscoelastics in Rabbits

PURPOSE

We developed a surgical method for localized and atraumatic removal of the retinal pigment epithelium (RPE) with a novel instrument.

METHODS

Bleb retinal detachments (bRD) were raised with balanced salt solution (BSS) following vitrectomy in 27 rabbits. The RPE was scraped with 3 loop variants (polypropylene [PP], 0.1 mm; PP, 0.06 mm; metal, 0.1 mm) of a custom-made instrument. Stabilization of bRDs with BSS or various concentrations (0.1%-0.5%) of hyaluronic acid (HA) was video analyzed. Perfusion-fixed samples of scraped areas and controls were studied by light and transmission electron microscopy.

RESULTS

The bRDs were sufficiently stabilized by ≥0.25% HA. Using the PP 0.1 mm loop with a single forward/backward stroke, an area of ca. 2.5 × 1.5 mm was nearly devoid of RPE, yet did show occasional Bruch's membrane (BM) defects combined with choriocapillaris hemorrhages in 13% of the bRDs. A single scrape with PP 0.06 mm resulted in unsatisfactory RPE denudement, while repeated scraping maneuvers caused more BM defects and hemorrhages. The metal loop resulted in incomplete RPE removal and massive intraoperative subretinal hemorrhages. Histologically, intact photoreceptor outer segments (POS) were observed above the RPE wounds in bRDs. Controls with bRDs alone showed an intact RPE monolayer with microvilli, with few engulfed remains of POS.

CONCLUSIONS

Localized removal of RPE in HA stabilized bRD can be achieved by a PP 0.1 mm loop instrument.

TRANSLATIONAL RELEVANCE

Removal of degenerated RPE may aid RPE cell replacement strategies.

[Intraoperative OCT in ophthalmic microsurgery]

Recent improvements in technology have enabled integration of SD-OCT into the optical path of an operating microscope. Here we present an overview of possible applications of iOCT (intraoperative optical coherence tomography) for retinal, glaucoma and corneal surgery. iOCT-based imaging can not only improve safety and quality of the surgery but also the learning curve of the surgeon. The ability to visualize barely visible or transparent structures with iOCT has achieved a significant added value intraoperatively, particularly in macular surgery, trabeculectomy and lamellar keratoplasty. Further, systematic assessment is warranted to define the usefulness of the iOCT more precisely.

Human RPE stem cells grown into polarized RPE monolayers on a polyester matrix are maintained after grafting into rabbit subretinal space

Transplantation of the retinal pigment epithelium (RPE) is being developed as a cell-replacement therapy for age-related macular degeneration. Human embryonic stem cell (hESC) and induced pluripotent stem cell (iPSC)-derived RPE are currently translating toward clinic. We introduce the adult human RPE stem cell (hRPESC) as an alternative RPE source. Polarized monolayers of adult hRPESC-derived RPE grown on polyester (PET) membranes had near-native characteristics. Trephined pieces of RPE monolayers on PET were transplanted subretinally in the rabbit, a large-eyed animal model. After 4 days, retinal edema was observed above the implant, detected by spectral domain optical coherence tomography (SD-OCT) and fundoscopy. At 1 week, retinal atrophy overlying the fetal or adult transplant was observed, remaining stable thereafter. Histology obtained 4 weeks after implantation confirmed a continuous polarized human RPE monolayer on PET. Taken together, the xeno-RPE survived with retained characteristics in the subretinal space. These experiments support that adult hRPESC-derived RPE are a potential source for transplantation therapies.

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Adult hRPESC-derived RPE had comparable in vitro characteristics to fetal hRPE

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hRPE monolayers survived 4 weeks on PET carriers under the rabbit retina

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Better xenograft survival may be due to the maintained hRPE cell polarity

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Atrophy of the retina overlaying the hRPE xenograft remains a future challenge

Subretinal delivery of ultrathin rigid-elastic cell carriers using a metallic shooter instrument and biodegradable hydrogel encapsulation

PURPOSE

To develop a surgical technique for the subretinal implantation of cell carriers suitable for the transplantation of cultured retinal pigment epithelium (RPE) in a preclinical animal model.

METHODS

Cell carriers were porous 10-μm-thick polyester membranes. A custom-made shooter instrument consisted of a 20-gauge metallic nozzle with a nonstick plunger. Fetal human RPE cultures were used for vitality assessment during instrument handling. Transvitreal subretinal implantation of carriers without RPE was performed in 31 rabbits after vitrectomy. Fourteen of 31 implants were encapsulated in gelatin. Fluid turbulence over the implantation site was minimized using a novel infusion cannula. Six rabbits had intravitreal plasmin injections before surgery. SD-OCT in vivo images were obtained after 3, 7, and 14 days, followed by perfusion-fixed histology.

RESULTS

Gelatin encapsulation of RPE/polyester implants made cell loss during handling reproducible, compared with 40% of controls showing random, large damage zones. Gelatin implants were ejected smoothly in 12 of 14 surgeries (86%), whereas "naked" implants frequently became trapped with the instrument, which reduced success to 9 of 17 cases (53%). Vitreous remnants after vitrectomy alone complicated subretinal placement of encapsulated and naked implants in 7 of 25 cases (28%). Plasmin-assisted vitrectomy resulted in implant ejection unperturbed by vitreous adhesions in six experiments. SD-OCT and histology demonstrated atraumatic subretinal implant delivery after uncomplicated surgery.

CONCLUSIONS

A novel shooter instrument design allows for safe and atraumatic transvitreal delivery of hydrogel-encapsulated, ultrathin, rigid-elastic carriers into the subretinal space. The procedure may be used in the future to deliver cultured RPE.

Intraocular humidity immediately after fluid–air exchange in pars plana vitrectomy

PURPOSE

To study vitreous cavity humidity during fluid-air exchange in pars plana vitrectomy.

METHODS

Intraocular humidity in the vitreous cavity was recorded for 2 min in six artificial eyes, six enucleated pig eyes, and ten patient eyes, after the eyes had been filled with either humidified air (75% humidity) or dry air (8% humidity).

RESULTS

In artificial eyes the humidity levelled off at a value that was approximately equal to the humidity of the infused air, i.e., a mean of 71.9% when humidified air was used and a mean of 14.4% when dry air was used. In enucleated pig eyes humidity increased slightly with humidified air and remained stable with dry air. In patients intraocular humidity increased to over 90%, regardless of whether humidified or dry air was used.

CONCLUSION

In the living eye, dry air deprives the retinal tissue of humidity, which is lost into the vitreous cavity. This effect can be reduced by using humidified air.