Jean-Pierre Hubschman

Embryonic stem cell trials for macular degeneration: a preliminary report

BACKGROUND It has been 13 years since the discovery of human embryonic stem cells (hESCs). Our report provides the first description of hESC-derived cells transplanted into human patients. METHODS We started two prospective clinical studies to establish the safety and tolerability of subretinal transplantation of hESC-derived retinal pigment epithelium (RPE) in patients with Stargardts macular dystrophy and dry age-related macular degeneration--the leading cause of blindness in the developed world. Preoperative and postoperative ophthalmic examinations included visual acuity, fluorescein angiography, optical coherence tomography, and visual field testing. These studies are registered with ClinicalTrials.gov, numbers NCT01345006 and NCT01344993. FINDINGS Controlled hESC differentiation resulted in greater than 99% pure RPE. The cells displayed typical RPE behaviour and integrated into the host RPE layer forming mature quiescent monolayers after transplantation in animals. The stage of differentiation substantially affected attachment and survival of the cells in vitro after clinical formulation. Lightly pigmented cells attached and spread in a substantially greater proportion (>90%) than more darkly pigmented cells after culture. After surgery, structural evidence confirmed cells had attached and continued to persist during our study. We did not identify signs of hyperproliferation, abnormal growth, or immune mediated transplant rejection in either patient during the first 4 months. Although there is little agreement between investigators on visual endpoints in patients with low vision, it is encouraging that during the observation period neither patient lost vision. Best corrected visual acuity improved from hand motions to 20/800 (and improved from 0 to 5 letters on the Early Treatment Diabetic Retinopathy Study [ETDRS] visual acuity chart) in the study eye of the patient with Stargardts macular dystrophy, and vision also seemed to improve in the patient with dry age-related macular degeneration (from 21 ETDRS letters to 28). INTERPRETATION The hESC-derived RPE cells showed no signs of hyperproliferation, tumorigenicity, ectopic tissue formation, or apparent rejection after 4 months. The future therapeutic goal will be to treat patients earlier in the disease processes, potentially increasing the likelihood of photoreceptor and central visual rescue. FUNDING Advanced Cell Technology.

Human embryonic stem cell-derived retinal pigment epithelium in patients with age-related macular degeneration and Stargardt's macular dystrophy: follow-up of two open-label phase 1/2 studies

BACKGROUND Since they were first derived more than three decades ago, embryonic stem cells have been proposed as a source of replacement cells in regenerative medicine, but their plasticity and unlimited capacity for self-renewal raises concerns about their safety, including tumour formation ability, potential immune rejection, and the risk of differentiating into unwanted cell types. We report the medium-term to long-term safety of cells derived from human embryonic stem cells (hESC) transplanted into patients. METHODS In the USA, two prospective phase 1/2 studies were done to assess the primary endpoints safety and tolerability of subretinal transplantation of hESC-derived retinal pigment epithelium in nine patients with Stargardts macular dystrophy (age >18 years) and nine with atrophic age-related macular degeneration (age >55 years). Three dose cohorts (50,000, 100,000, and 150,000 cells) were treated for each eye disorder. Transplanted patients were followed up for a median of 22 months by use of serial systemic, ophthalmic, and imaging examinations. The studies are registered with ClinicalTrials.gov, numbers NCT01345006 (Stargardts macular dystrophy) and NCT01344993 (age-related macular degeneration). FINDINGS There was no evidence of adverse proliferation, rejection, or serious ocular or systemic safety issues related to the transplanted tissue. Adverse events were associated with vitreoretinal surgery and immunosuppression. 13 (72%) of 18 patients had patches of increasing subretinal pigmentation consistent with transplanted retinal pigment epithelium. Best-corrected visual acuity, monitored as part of the safety protocol, improved in ten eyes, improved or remained the same in seven eyes, and decreased by more than ten letters in one eye, whereas the untreated fellow eyes did not show similar improvements in visual acuity. Vision-related quality-of-life measures increased for general and peripheral vision, and near and distance activities, improving by 16-25 points 3-12 months after transplantation in patients with atrophic age-related macular degeneration and 8-20 points in patients with Stargardts macular dystrophy. INTERPRETATION The results of this study provide the first evidence of the medium-term to long-term safety, graft survival, and possible biological activity of pluripotent stem cell progeny in individuals with any disease. Our results suggest that hESC-derived cells could provide a potentially safe new source of cells for the treatment of various unmet medical disorders requiring tissue repair or replacement. FUNDING Advanced Cell Technology.

THz Medical Imaging: in vivo Hydration Sensing

The application of THz to medical imaging is experiencing a surge in both interest and federal funding. A brief overview of the field is provided along with promising and emerging applications and ongoing research. THz imaging phenomenology is discussed and tradeoffs are identified. A THz medical imaging system, operating at ~525 GHz center frequency with ~125 GHz of response normalized bandwidth is introduced and details regarding principles of operation are provided. Two promising medical applications of THz imaging are presented: skin burns and cornea. For burns, images of second degree, partial thickness burns were obtained in rat models in vivo over an 8 hour period. These images clearly show the formation and progression of edema in and around the burn wound area. For cornea, experimental data measuring the hydration of ex vivo porcine cornea under drying is presented demonstrating utility in ophthalmologic applications.

Ultra Wide-Field Angiographic Characteristics of Branch Retinal and Hemicentral Retinal Vein Occlusion

PURPOSE To study the peripheral angiographic features of branch retinal vein occlusions (BRVO) and hemicentral retinal vein occlusions (HRVO) and explore associations with macular edema and neovascularization. DESIGN Retrospective observational case series. PARTICIPANTS Seventy-eight outpatients. METHODS An imaging database of angiograms performed at a single academic institution was searched for patients with a diagnosis of BRVO or HRVO. Images were graded for the presence of untreated nonperfusion (areas without evidence of laser photocoagulation), late peripheral vascular leakage (LPVL), neovascularization, macular edema, and prior laser treatment. Optical coherence tomography images were reviewed for all patients to confirm the presence of macular thickening and to exclude eyes with vitreomacular traction. MAIN OUTCOME MEASURES Angiographic evidence of nonperfusion, neovascularization, macular edema, LPVL, and prior laser treatment. RESULTS Angiograms from 80 eyes of 78 patients were analyzed with a diagnosis of BRVO (86%) or HRVO (14%). Angiographic macular edema (80%), untreated nonperfusion (82%), neovascularization (21%), and LPVL (58%) were observed. Untreated nonperfusion at any location was significantly associated with macular edema (P = 0.043). Untreated nonperfusion anterior to the globe equator was significantly associated with macular edema (P = 0.007). Untreated nonperfusion was significantly associated with the presence of neovascularization (P = 0.033). Late peripheral vascular leakage was not associated with other angiographic or clinical findings studied. CONCLUSIONS Ultra wide-field angiography provides visualization of peripheral retinal pathology in BRVO and HRVO patients, which may be useful in their evaluation and treatment. Our findings support the hypothesis that areas of untreated retinal nonperfusion may be the source of production of biochemical mediators that promote neovascularization and macular edema. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found after the references.

Terahertz sensing in corneal tissues.

This work introduces the potential application of terahertz (THz) sensing to the field of ophthalmology, where it is uniquely suited due to its nonionizing photon energy and high sensitivity to water content. Reflective THz imaging and spectrometry data are reported on ex-vivo porcine corneas prepared with uniform water concentrations using polyethylene glycol (PEG) solutions. At 79% water concentration by mass, the measured reflectivity of the cornea was 20.4%, 14.7%, 11.7%, 9.6%, and 7.4% at 0.2, 0.4, 0.6, 0.8, and 1 THz, respectively. Comparison of nine corneas hydrated from 79.1% to 91.5% concentration by mass demonstrated an approximately linear relationship between THz reflectivity and water concentration, with a monotonically decreasing slope as the frequency increases. The THz-corneal tissue interaction is simulated with a Bruggeman model with excellent agreement. THz applications to corneal dystrophy, graft rejection, and refractive surgery are examined from the context of these measurements.

Ischemic index and neovascularization in central retinal vein occlusion.

Purpose: To explore the association of angiographic nonperfusion with anterior segment and posterior segment neovascularization in central retinal vein occlusion (CRVO). Methods: An imaging database at one institution was searched for the diagnosis of central retinal vein occlusion. Ultra wide field fluorescein angiograms were graded for image quality, the presence of retinal neovascularization, and the quantity of nonperfusion; an ischemic index (ISI) was calculated. Charts were reviewed to exclude eyes with previous treatment and to determine which eyes had anterior segment or posterior segment neovascularization on the day of the angiogram. Time from onset to presentation could not accurately be ascertained. Results: In a 39-month period, there were 69 eyes that met inclusion criteria. The mean ISI was 25% (SD, 26%; range, 0-100%), and 15 eyes (21%) with neovascularization had a mean ISI of 75% (range, 47-100%) compared with eyes without neovascularization that had an ISI of 6% (range, 0-43%). Ischemic index significantly correlated to neovascularization, and eyes that had evidence of neovascularization had an ISI >45% (P < 0.0001). Conclusion: Ultra wide field fluorescein angiography provides visualization of nonperfusion in eyes with central retinal vein occlusion. Eyes with neovascularization on the day of the angiogram were found to have significantly larger areas of retinal nonperfusion compared with eyes without neovascularization. A prospective study is indicated to know if early treatment of peripheral retinal nonperfusion in CRVO improves outcomes.

20-, 23-, and 25-gauge vitreous cutters: performance and characteristics evaluation.

Purpose: The flow rate of nine vitreous cutters was tested in two different viscosity environments. Physical features of each probe, such as flexibility and internal lumen diameter, were measured. Methods: For each probe, a total of 26 aspiration tests were performed in two different liquids. The stiffness of the shaft of each probe was calculated by measuring the displacement of the tip of the probe under a known constant force. All the probes were dissected and the internal lumen diameter was measured. Results: Significant differences in flow rates were observed among the three separate conditions, among the three different gauge groups (25-, 23-, and 20-gauge vitreous cutter), and also within each gauge group. Internal lumen diameters and probe stiffness characteristics are presented. Conclusion: Vacuum, internal lumen diameter, and duty cycle seem to be the critical features governing actual flow rate. Knowledge of flow rate and stiffness of the various probes may aid surgeons in making an educated choice and may improve patient care.

Feasibility study of intraocular robotic surgery with the da Vinci surgical system.

Purpose: To assess the feasibility of performing intraocular robotic surgery with the da Vinci Surgical System (Intuitive Surgical, Sunnyvale, CA). Methods: Using modified robotic instruments, 25-gauge pars plana vitrectomy, intraocular foreign body removal, and anterior capsulorhexis were performed with the da Vinci system on porcine eyes. We assessed the surgical system’s ability to provide the control, dexterity, maneuverability, and visualization necessary for intraocular surgery. Results: Control of the robotic wristlike instruments allowed for full range of movement. The dexterity of the robotic arms was excellent, with steady instrument motion. Controlling the robotic arms was not as intuitive as moving the wrist. A high stable point of rotation induced motion-related stress at the site of instrument insertion. Visualization of the external operative field during intraocular procedures required camera realignment, and absent retroillumination made anterior segment surgery hard to perform. Conclusions: The da Vinci Surgical System provided adequate dexterity for performing delicate intraocular manipulations. In the current design, the kinematics of the robotic arms was found to be insufficient for standard intraocular surgery. The system’s endoscope did not did not yield the same detail acquired by an ophthalmic microscope.

Spectrum of Retinal Vascular Diseases Associated With Paracentral Acute Middle Maculopathy.

PURPOSE To evaluate the spectrum of retinal diseases that can demonstrate paracentral acute middle maculopathy and isolated ischemia of the intermediate and deep capillary plexus. DESIGN Retrospective, multicenter, observational case series. METHODS This is a retrospective case series review of 9 patients (10 eyes) from 5 centers with paracentral acute middle maculopathy lesions and previously unreported retinal vascular etiologies. Case presentations and multimodal imaging, including color photographs, near-infrared reflectance, fluorescein angiography, spectral-domain optical coherence tomography (SD OCT), and orbital color Doppler imaging, are described. Baseline and follow-up findings are correlated with clinical presentation, demographics, and systemic associations. RESULTS Five men and 4 women, aged 27-66 years, were included. Isolated band-like hyperreflective lesions in the middle retinal layers, otherwise known as paracentral acute middle maculopathy, were observed in all patients at baseline presentation. Follow-up SD OCT analysis of these paracentral acute middle maculopathy lesions demonstrated subsequent thinning of the inner nuclear layer. Novel retinal vascular associations leading to retinal vasculopathy and paracentral acute middle maculopathy include eye compression injury causing global ocular ischemia, sickle cell crisis, Purtschers retinopathy, inflammatory occlusive retinal vasculitis, post-H1N1 vaccine, hypertensive retinopathy, migraine disorder, and post-upper respiratory infection. CONCLUSION Paracentral acute middle maculopathy lesions may develop in a wide spectrum of retinal vascular diseases. They are best identified with SD OCT analysis and may represent ischemia of the intermediate and deep capillary plexus. These lesions typically result in permanent thinning of the inner nuclear layer and are critical to identify in order to determine the cause of unexplained vision loss.

Validating retinal fundus image analysis algorithms: Issues and a proposal

This paper concerns the validation of automatic retinal image analysis (ARIA) algorithms. For reasons of space and consistency, we concentrate on the validation of algorithms processing color fundus camera images, currently the largest section of the ARIA literature. We sketch the context (imaging instruments and target tasks) of ARIA validation, summarizing the main image analysis and validation techniques. We then present a list of recommendations focusing on the creation of large repositories of test data created by international consortia, easily accessible via moderated Web sites, including multicenter annotations by multiple experts, specific to clinical tasks, and capable of running submitted software automatically on the data stored, with clear and widely agreed-on performance criteria, to provide a fair comparison.