Long-term outcomes for pediatric patients having transscleral fixation of the capsular bag with intraocular lens for ectopia lentis

PURPOSE

To report the long-term outcomes of transscleral fixation of capsular tension rings (CTR) with intraocular lens (IOL) placement in pediatric patients with ectopia lentis.

SETTING

John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.

DESIGN

Retrospective case series.

METHODS

Pediatric patients requiring lens extraction with transscleral capsular bag fixation with a CTR and IOL for ectopia lentis between January 2006 and January 2016 were analyzed.

RESULTS

Thirty-seven patients (67 eyes) who had transscleral fixation of the capsular bag using a CTR fixated with 9-0 or 10-0 polypropylene (Prolene), 8-0 polytetrafluoroethylene (Gore-Tex), or 9-0 nylon were identified. The mean age at time of surgery was 7.25 years (2 to 18 years) and the mean follow-up was 35.3 months (0.25 to 120 months). The proportion of eyes showing improvement in corrected distance visual acuity (CDVA) postoperatively was 78.5%, which demonstrated significance with a 95% confidence interval. In the immediate postoperative period, 1 eye developed a hyphema and 1 eye required IOL repositioning. Long-term complications included posterior capsule opacification in 35 eyes (52%) and uveitis-glaucoma-hyphema syndrome in 1 eye (1.5%). Three eyes (4.4 %) required IOL repositioning for spontaneous delayed IOL dislocation, 2 sutured with 8-0 polytetrafluoroethylene at postoperative month 8 and postoperative year 3 and 1 sutured with 9-0 polypropylene at postoperative year 7.

CONCLUSION

Transscleral fixation of the capsular bag using a CTR improved CDVA and provided IOL stability in pediatric patients with ectopia lentis.

Comparing consistency of clear corneal incisions using a traditional diamond keratome and a newly designed diamond keratome

Purpose

To compare the consistency of incision architecture utilizing a traditional diamond keratome and a newly designed diamond keratome.

Methods

We used a traditional diamond keratome and newly designed diamond keratome to create clear corneal incisions in human cadaveric donor eyes. Three surgeons with varying levels of experience made 30 incisions with each keratome; and the wound architecture was measured including incision lengths, epithelial and endothelial widths, and the central epithelial incision’s deviation from a straight line entrance.

Results

The mean absolute difference in right and left incision lengths (traditional: 0.182 ± 0.158 mm and new 0.088±0.077 mm [P<0.003]), mean absolute difference in epithelial and endothelial incision width (traditional: 0.181±0.144 mm and new 0.080±0.092 mm [P<0.002]), endothelial incision central deviation from a straight line (traditional: 0.128±0.242 mm and new −0.046±0.124 mm [P<0.001]) were all significantly more consistent with the newly designed diamond keratome than with the traditional diamond keratome.

Conclusion

The newly designed diamond keratome creates a more consistent clear corneal incision than a traditional diamond keratome across a variety of surgical skill levels and does not require advanced levels of training to achieve this consistency.

A pilot study on providing ophthalmic training to medical students while initiating a sustainable eye care effort for the underserved

IMPORTANCE

We present a method to reintroduce ophthalmic training into the medical school curriculum.

OBJECTIVES

To evaluate knowledge and skills acquired when participating in a service project, the Community Vision Project, and to develop a quantitative method for testing skills with the direct ophthalmoscope in patients.

DESIGN

Second-year medical students participated in the study. After 1 month, their knowledge was compared with that of peers and graduates (internal medicine residents). Also at 1 month, their direct ophthalmoscope skills were compared with those of upperclassmen who had completed all core clerkships. One year later, after the participants had completed their core clerkships, long-term ophthalmoscope skills retention was tested, and their performance was compared with that of their classmates.

SETTING AND PARTICIPANTS

Training occurred in mobile eye clinics. Knowledge and skills assessments were performed in the hospital eye clinic among students and residents at The University of New Mexico School of Medicine. Patients were recruited from the hospital eye clinic. Participants attended a 3-hour training session held by an attending physician in the hospital eye clinic and took part in at least 1 mobile eye clinic.

MAIN OUTCOMES AND MEASURES

A knowledge assessment quiz was administered to participants (n = 12), their classmates (n = 18), and internal medicine residents (n = 33). Skills assessment with the direct ophthalmoscope was performed at 1 month and at 1 year in 5 participants and 5 nonparticipants. Tonometer skills were assessed by comparing participants' readings with those of an ophthalmologist's obtained in patients at the mobile eye clinics. RESULTS Participants' median knowledge assessment scores were 48% higher than those of their classmates and 37% higher than those of internal medicine residents (P < .001 for both). Short-term (1 month) direct ophthalmoscopy median scores were 60% (quartile 1 to quartile 3 range, 40%-80%) for participants and 40% (quartile 1 to quartile 3 range, 20%-60%) for nonparticipating upperclassmen (P = .24). Long-term direct ophthalmoscopy median scores were 100% (quartile 1 to quartile 3 range, 75%-100%) for participants and 0% (quartile 1 to quartile 3 range, 0%-25%) for nonparticipating classmates (P = .11). Participants' tonometer readings were similar to those of the ophthalmologist's; their median reading was 2 mm Hg (quartile 1 to quartile 3 range, 0-4 mm Hg) higher than that of the ophthalmologist's (P = .05, sign test).

CONCLUSIONS AND RELEVANCE

Service-based learning offered an efficient model for incorporating ophthalmic training into the medical school curriculum. A viable tool for quantitatively testing ophthalmoscope skills is presented.

Stable transmission of radio frequency signals on fiber links using interferometric delay sensing

We demonstrate distribution of a 2850 MHz rf signal over stabilized optical fiber links. For a 2.2 km link we measure an rms drift of 19.4 fs over 60 h, and for a 200 m link an rms drift of 8.4 fs over 20 h. The rf signals are transmitted as amplitude modulation on a continuous optical carrier. Variations in the delay length are sensed using heterodyne interferometry and used to correct the rf phase. The system uses standard fiber telecommunications components.

Measurement of electron clouds in large accelerators by microwave dispersion

Clouds of low energy electrons in the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation at high currents. Furthermore, it is difficult to probe their density over substantial lengths of the beam pipe. We have developed a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave transmitted over a section of the accelerator and used it to measure the average electron cloud density over a 50 m section in the positron ring of the PEP-II collider at the Stanford Linear Accelerator Center.

Laser seeding of the storage-ring microbunching instability for high-power coherent terahertz radiation

We report the first observation of laser seeding of the storage-ring microbunching instability. Above a threshold bunch current, the interaction of the beam and its radiation results in a coherent instability, observed as a series of stochastic bursts of coherent synchrotron radiation (CSR) at terahertz frequencies initiated by fluctuations in the beam density. We have observed that this effect can be seeded by imprinting an initial density modulation on the beam by means of laser "slicing." In such a situation, most of the bursts of CSR become synchronous with the pulses of the modulating laser and their average intensity scales exponentially with the current per bunch. We present detailed experimental observations of the seeding effect and a model of the phenomenon. This seeding mechanism also creates potential applications as a high-power source of CSR at terahertz frequencies.

Tailored terahertz pulses from a laser-modulated electron beam

We present a new method to generate steady and tunable, coherent, broadband terahertz radiation from a relativistic electron beam modulated by a femtosecond laser. We have demonstrated this in the electron storage ring at the Advanced Light Source. Interaction of an electron beam with a femtosecond laser pulse copropagating through a wiggler modulates the electron energies within a short slice of the electron bunch with about the same duration of the laser pulse. The bunch develops a longitudinal density perturbation due to the dispersion of electron trajectories, and the resulting hole emits short pulses of temporally and spatially coherent terahertz pulses synchronized to the laser. We present measurements of the intensity and spectra of these pulses. This technique allows tremendous flexibility in shaping the terahertz pulse by appropriate modulation of the laser pulse.

A model describing stable coherent synchrotron radiation in storage rings

We present a model describing high power stable broadband coherent synchrotron radiation (CSR) in the terahertz frequency region in an electron storage ring. The model includes distortion of bunch shape from the synchrotron radiation (SR), which enhances higher frequency coherent emission, and limits to stable emission due to an instability excited by the SR wakefield. It gives a quantitative explanation of several features of the recent observations of CSR at the BESSY II storage ring. We also use this model to optimize the performance of a source for stable CSR emission.

Observation of broadband self-amplified spontaneous coherent terahertz synchrotron radiation in a storage ring

Bursts of coherent synchrotron radiation at far-infrared and millimeter wavelengths have been observed at several storage rings. A microbunching instability has been proposed as the source for the bursts. However, the microbunching mechanism has yet to be elucidated. We provide the first evidence that the bursts are due to a microbunching instability driven by the emission of synchrotron radiation in the bunch. Observations made at the Advanced Light Source are consistent with the values predicted by the proposed microbunching model. These results demonstrate a new instability regime for high energy synchrotron radiation sources and could impact the design of future sources.