Evaluation of the prophylactic use of mitomycin-C to inhibit haze formation after photorefractive keratectomy in high myopia: a prospective clinical study

BACKGROUND: To study the effect of prophylactic application of mitomycin-C on haze formation in photorefractive keratectomy (PRK) for high myopia. METHODS: Fifty-four eyes of 28 myopic patients were enrolled in this prospective study. All eyes were operated by PRK followed by 0.02% mitomycin-C application for two minutes and washed with 20 ml normal saline afterwards. All eyes were examined thoroughly on the first 7 days and one month after surgery; 48 eyes (88.9%) at 3 and 6 months postoperatively. Hanna grading (in the scale of 0 to 4+) was used for assessment of corneal haze. RESULTS: The mean spherical equivalent refraction (SE) was -7.08 diopters (D) ± 1.11 (SD) preoperatively. Six months after surgery, 37 eyes (77.1%) achieved an uncorrected visual acuity (UCVA) of 20/20 or better, all eyes had a UCVA of 20/40 or better and 45 (93.7%) eyes had an SE within ± 1.00D. One month postoperatively, 2 eyes (3.7%) had grade 0.5+ of haze, while at 3 and 6 months after surgery no visited eye had haze at all. All eyes had a best corrected visual acuity (BCVA) of 20/40 or better and there were no lost lines in BCVA by 6 months after surgery. In spatial frequencies of 6 and 12 cycles per degree contrast sensitivity had decreased immediately after PRK and it had increased 1.5 lines by the 6(th )postoperative month compared to the preoperative data. CONCLUSIONS: The results show the efficacy of mitomycin-C in preventing corneal haze after treatment of high myopia with PRK. This method- PRK + mitomycin-C – can be considered an alternative treatment for myopic patients whose corneal thicknesses are inadequate for laser in situ keratomileusis (LASIK). However, the results should be confirmed in longer follow-ups

LiteBIRD Science Goals and Forecasts. A Case Study of the Origin of Primordial Gravitational Waves using Large-Scale CMB Polarization

We study the possibility of using the $LiteBIRD$ satellite $B$-mode survey to constrain models of inflation producing specific features in CMB angular power spectra. We explore a particular model example, i.e. spectator axion-SU(2) gauge field inflation. This model can source parity-violating gravitational waves from the amplification of gauge field fluctuations driven by a pseudoscalar "axionlike" field, rolling for a few e-folds during inflation. The sourced gravitational waves can exceed the vacuum contribution at reionization bump scales by about an order of magnitude and can be comparable to the vacuum contribution at recombination bump scales. We argue that a satellite mission with full sky coverage and access to the reionization bump scales is necessary to understand the origin of the primordial gravitational wave signal and distinguish among two production mechanisms: quantum vacuum fluctuations of spacetime and matter sources during inflation. We present the expected constraints on model parameters from $LiteBIRD$ satellite simulations, which complement and expand previous studies in the literature. We find that $LiteBIRD$ will be able to exclude with high significance standard single-field slow-roll models, such as the Starobinsky model, if the true model is the axion-SU(2) model with a feature at CMB scales. We further investigate the possibility of using the parity-violating signature of the model, such as the $TB$ and $EB$ angular power spectra, to disentangle it from the standard single-field slow-roll scenario. We find that most of the discriminating power of $LiteBIRD$ will reside in $BB$ angular power spectra rather than in $TB$ and $EB$ correlations.Comment: 22 pages, 13 figures. Submitted to JCA

Concept design of low frequency telescope for CMB B-mode polarization satellite LiteBIRD

LiteBIRD has been selected as JAXA’s strategic large mission in the 2020s, to observe the cosmic microwave background (CMB) B-mode polarization over the full sky at large angular scales. The challenges of LiteBIRD are the wide field-of-view (FoV) and broadband capabilities of millimeter-wave polarization measurements, which are derived from the system requirements. The possible paths of stray light increase with a wider FoV and the far sidelobe knowledge of -56 dB is a challenging optical requirement. A crossed-Dragone configuration was chosen for the low frequency telescope (LFT : 34–161 GHz), one of LiteBIRD’s onboard telescopes. It has a wide field-of-view (18° x 9°) with an aperture of 400 mm in diameter, corresponding to an angular resolution of about 30 arcminutes around 100 GHz. The focal ratio f/3.0 and the crossing angle of the optical axes of 90◦ are chosen after an extensive study of the stray light. The primary and secondary reflectors have rectangular shapes with serrations to reduce the diffraction pattern from the edges of the mirrors. The reflectors and structure are made of aluminum to proportionally contract from warm down to the operating temperature at 5 K. A 1/4 scaled model of the LFT has been developed to validate the wide field-of-view design and to demonstrate the reduced far sidelobes. A polarization modulation unit (PMU), realized with a half-wave plate (HWP) is placed in front of the aperture stop, the entrance pupil of this system. A large focal plane with approximately 1000 AlMn TES detectors and frequency multiplexing SQUID amplifiers is cooled to 100 mK. The lens and sinuous antennas have broadband capability. Performance specifications of the LFT and an outline of the proposed verification plan are presented

LiteBIRD satellite: JAXA's new strategic L-class mission for all-sky surveys of cosmic microwave background polarization

LiteBIRD, the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission for primordial cosmology and fundamental physics. JAXA selected LiteBIRD in May 2019 as a strategic large-class (L-class) mission, with its expected launch in the late 2020s using JAXA's H3 rocket. LiteBIRD plans to map the cosmic microwave background (CMB) polarization over the full sky with unprecedented precision. Its main scientific objective is to carry out a definitive search for the signal from cosmic inflation, either making a discovery or ruling out well-motivated inflationary models. The measurements of LiteBIRD will also provide us with an insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. To this end, LiteBIRD will perform full-sky surveys for three years at the Sun-Earth Lagrangian point L2 for 15 frequency bands between 34 and 448 GHz with three telescopes, to achieve a total sensitivity of 2.16 μK-arcmin with a typical angular resolution of 0.5° at 100 GHz. We provide an overview of the LiteBIRD project, including scientific objectives, mission requirements, top-level system requirements, operation concept, and expected scientific outcomes

Overview of the medium and high frequency telescopes of the LiteBIRD space mission

LiteBIRD is a JAXA-led Strategic Large-Class mission designed to search for the existence of the primordial gravitational waves produced during the inflationary phase of the Universe, through the measurements of their imprint onto the polarization of the cosmic microwave background (CMB). These measurements, requiring unprecedented sensitivity, will be performed over the full sky, at large angular scales, and over 15 frequency bands from 34 GHz to 448 GHz. The LiteBIRD instruments consist of three telescopes, namely the Low-, Medium-and High-Frequency Telescope (respectively LFT, MFT and HFT). We present in this paper an overview of the design of the Medium-Frequency Telescope (89{224 GHz) and the High-Frequency Telescope (166{448 GHz), the so-called MHFT, under European responsibility, which are two cryogenic refractive telescopes cooled down to 5 K. They include a continuous rotating half-wave plate as the first optical element, two high-density polyethylene (HDPE) lenses and more than three thousand transition-edge sensor (TES) detectors cooled to 100 mK. We provide an overview of the concept design and the remaining specific challenges that we have to face in order to achieve the scientific goals of LiteBIRD

Influence of co-payment levels on patient and surgeon acceptance of advanced technology intraocular lenses.

PURPOSE: To investigate patients' willingness to pay for advanced technology intraocular lenses and surgeons' willingness to recommend them. METHODS: In this study, 370 cataract surgeons and 700 patients undergoing cataract surgery from seven countries underwent online interviews in which they were shown unbranded profiles of three advanced technology intraocular lenses (ie, biconvex toric aspheric optic, symmetric biconvex diffractive optic, and biconvex diffractive aspheric toric) and asked to indicate their willingness to accept (for patients) or suggest (for surgeons) each lens. Acceptance was assessed assuming there was either no co-payment or co-payments of €500 to €1,500 +15%. RESULTS: All three lenses were widely accepted by patients, with 68% to 99% indicating acceptance when there was no co-payment. In contrast, surgeons' willingness to suggest them was markedly lower (20% to 43%). Both patients' acceptance of the lenses and surgeons' willingness to suggest them decreased with increasing co-payment levels to 19% to 74% (patients) and 5% to 31% (surgeons) at the highest co-payment levels. CONCLUSIONS: There is a marked discrepancy between patients' acceptance of the three lenses and surgeons' willingness to suggest them. Although patients' acceptance is high, it decreases with increasing out-of-pocket expenditure. Manufacturers should communicate the relative benefits and costs of their lenses to both surgeons and patients

Influence of co-payment levels on patient and surgeon acceptance of advanced technology intraocular lenses.

PURPOSE: To investigate patients' willingness to pay for advanced technology intraocular lenses and surgeons' willingness to recommend them. METHODS: In this study, 370 cataract surgeons and 700 patients undergoing cataract surgery from seven countries underwent online interviews in which they were shown unbranded profiles of three advanced technology intraocular lenses (ie, biconvex toric aspheric optic, symmetric biconvex diffractive optic, and biconvex diffractive aspheric toric) and asked to indicate their willingness to accept (for patients) or suggest (for surgeons) each lens. Acceptance was assessed assuming there was either no co-payment or co-payments of €500 to €1,500 +15%. RESULTS: All three lenses were widely accepted by patients, with 68% to 99% indicating acceptance when there was no co-payment. In contrast, surgeons' willingness to suggest them was markedly lower (20% to 43%). Both patients' acceptance of the lenses and surgeons' willingness to suggest them decreased with increasing co-payment levels to 19% to 74% (patients) and 5% to 31% (surgeons) at the highest co-payment levels. CONCLUSIONS: There is a marked discrepancy between patients' acceptance of the three lenses and surgeons' willingness to suggest them. Although patients' acceptance is high, it decreases with increasing out-of-pocket expenditure. Manufacturers should communicate the relative benefits and costs of their lenses to both surgeons and patients

Short-Term Effects of a Novel Eye Mask Producing Heat and Vibration for the Treatment of Meibomian Gland Dysfunction: A Pilot Study

Purpose. To investigate the short-Term effects on tear film parameters and ocular symptoms of a novel eye mask producing heat and vibration developed for the treatment of dry eye disease owing to meibomian gland dysfunction (MGD). Methods. This is a pilot study including the first 20 consecutive patients (6 males, 14 females; mean age 52.4 ± 16.8 years) who were treated with a novel eye mask producing heat (42°) and vibration (up to 20 Hz) (Activa, SBS Sistemi, Turin, Italy) for 15 minutes. The treatment incorporates 2 phases in the following chronological order: 5 minutes of heating (phase I); 10 minutes of combination of heating and vibration (phase II). Noninvasive ocular surface examination was carried out before (T0) and 30 minutes after the mask session (T1) by means of Idra (SBS Sistemi, Turin, Italy) for the measurement of noninvasive break-up time (NIBUT) and lipid layer thickness (LLT). Patients' satisfaction after treatment was ascertained by asking the patients whether they perceived improvement from their baseline symptoms according to a 5-grade scale: none = 0; trace = 1; mild = 2; moderate = 3; high = 4. Results. All patients completed regularly the mask session and no device-related adverse events were noted. NIBUT improved significantly from T0 to T1 (from 7.2 ± 1.8 s to 8.1 ± 2.1; P = 0.014). In parallel, also LLT improved from from T0 to T1 (72.5 ± 13.9 nm to 83.1 ± 16.1; P = 0.016). Seven patients (35% of the total) had a moderate satisfaction (grade 3) while 13 patients (65%) had a high satisfaction (grade 4) with treatment. Conclusions. This eye mask represents a novel well tolerated tool in the armamentarium of MGD treatments. Thirty minutes after the session, NIBUT and LLT increased significantly; furthermore, all patients reported an improvement of discomfort symptoms with a moderate to high satisfaction with treatment