Development of a miniaturized HIFU device for glaucoma treatment with conformal coagulation of the ciliary bodies

Endocyclophotocoagulation Combined with Phacoemulsification in Glaucoma Treatment: Five-Year Results

BACKGROUND

this study aimed to assess the effectiveness and safety of phaco-endocyclophotocoagulation (phaco-ECP) in patients with glaucoma over five consecutive years.

METHODS

Thirty-eight patients (38 eyes) with primary and secondary glaucoma were enrolled to undergo phaco-ECP (Endo Optiks URAM E2, Beaver-Visitec International, Waltham, MA, USA). The primary outcome measures were intraocular pressure (IOP) reduction, success rates, glaucoma medication use, and visual acuity after phaco-ECP. An IOP reduction of 20% compared to the baseline value without re-intervention was considered a successful treatment. Complete success was defined as a cessation of antiglaucoma medications. Secondary outcome measures included intraoperative and postoperative complications. Measurements were performed preoperatively and in the first week and 1, 3, 6, 12, 18, 24, 30, 36, 42, 48, 54, and 60 months postoperatively.

RESULTS

The mean ± SD values of IOP preoperatively, at 12, 24, 36, 48, and 60 months postoperatively were 22.6 ± 6.7 mmHg, 15.9 ± 3.9 mmHg (p < 0.001), 15.9 ± 2.9 mmHg (p < 0.001), 15.6 ± 2.7 mmHg (p < 0.001), 15.5 ± 3.8 mmHg (p < 0.001), and 15.2 ± 2.6 mmHg (p < 0.001), respectively. The mean IOP at the last follow-up was reduced by 32.7%. The decrease in the number of antiglaucoma medications was statistically significant at each follow-up visit compared to the baseline. The qualified success rate was 40.6%. All patients at the 60-month follow-up visit required the use of antiglaucoma medications-none of the patients achieved complete success. During the follow-up period, nine patients (28.3%) that required retreatment due to nonachievement of the target IOP were considered failures. Six patients (15.8%) were lost from the follow-up. A total of 23 patients were evaluated 60 months after their phaco-ECP. Complications directly associated with the procedure, such as corneal edema (25.6%), IOP spikes (20.5%), IOL dislocation (2.6%), and uveitis (12.8%), were observed in our patients. Hypotony was not observed in any of our patients.

CONCLUSIONS

The phaco-ECP procedure was effective, well-tolerated, and safe for reducing IOP in glaucoma patients with cataracts over a long-term follow-up. Randomized, larger-scale studies are required to validate the results obtained.

Minimally Invasive Glaucoma Surgery: Latest Developments and Future Challenges

The development of minimally invasive glaucoma surgeries (MIGSs) was intended to provide safe and modestly efficacious modalities for early intervention of mild-to-moderate glaucoma, with minimal trauma and rapid recovery. They were mainly ab interno procedures that reduce intraocular pressure by facilitating the aqueous outflow by bypassing the trabecular meshwork resistance, reinforcing the uveoscleral flow via the supraciliary space, and reducing aqueous production by the ciliary body. While the cumulating evidence helps shape the role of the available MIGS, the exponential new development and advancement in this field has expanded the territory of MIGS. Apart from developing subconjunctival MIGS filtration devices (Xen gel stent and PRESERFLO MicroShunt), there is a tendency to revisit the "traditional" MIGS for alternative use and to modify the procedures with consideration of the fundamental aqueous outflow physiology. Combined MIGS has also been suggested, based on the theory that their different mechanisms may provide additive or synergistic effects. The advancement of laser procedures is also promising and could supplement unmet needs along the glaucoma treatment algorithm. This review examines the broad array of MIGS, updates the recent findings, discusses their potential alternative applications, and explores future challenges.

The Agreement of the Nomogram Tool and Ultrasound Biomicroscopy Images in Calculating Ultrasound Cycloplasty Probe Model in Chinese Patients

PURPOSE

The aim of the study was to compare and explore the agreement between the nomogram tool and ultrasound biomicroscopy (UBM) images method to calculate the ultrasound cycloplasty (UCP) probe model in Chinese glaucoma patients.

METHODS

Retrospective analysis of Chinese glaucoma patients who visited Zhongshan Ophthalmic Center in Guangzhou from January to December 2019 and were eligible for UCP surgery. Visual acuity, intraocular pressure (IOP), ocular axial length (AL), and horizontal corneal diameter (white to white [WTW]) were measured. UBM images with clear ciliary body imaging and AL and WTW data were sent to trained personnel for probe model measurements. The data calculated by both methods were analyzed using unweighted and weighted κ statistics. The level of agreement refers to Landis and Koch's guideline for the strength of agreement indicated with weighted κ values.

RESULTS

1,061 eyes of 642 patients were involved, with a mean age of 61.66 ± 11.66 years. Their best-corrected visual acuity converted to logarithm of minimal-angle-of-resolution (logMAR) scores of -0.18-3.00 with a mean value of 0.69 ± 0.77. IOP was 22.0-60.0 mm Hg with a mean of 27.97 ± 5.66 mm Hg. The mean AL and WTW were 22.88 ± 1.33 (19.15-32.14) mm and 11.52 ± 0.49 (10.00-12.90) mm, respectively. The agreement between the two methods was fair (weighted κ = 0.299), matching in 62.86% of eyes (weighted κ = 0.299, κ = 0.264). The agreement in primary open angle glaucoma, acute primary angle-closure glaucoma, chronic primary angle-closure glaucoma, and secondary glaucoma patients was 60.85% (weighted κ = 0.336, κ = 0.301), 65.06% (weighted κ = 0.146, κ = 0.127), 62.26% (weighted κ = 0.204, κ = 0.184), and 57.97% (weighted κ = 0.332, κ = 0.280) of eyes, respectively.

CONCLUSION

The agreement between UBM images and the nomogram tool to calculate the UCP probe model of Chinese patients is at a fair level. The nomogram tool prefers to use larger probes. Improvements to the nomogram tool, such as including data from more ethnic groups and being able to calculate separately for different types of glaucoma, are needed to improve accuracy. The inclusion of parameters or images from more directions of the eye may help measure probe models more accurately for both the nomogram tool and the UBM image measurement.

Efficacy and safety of ultrasound cycloplasty in Indian eyes with open-angle glaucoma

Purpose

To evaluate the safety and efficacy of ultrasound cycloplasty in eyes with primary or secondary open-angle glaucoma, not amenable to adequate control of intra-ocular pressure (IOP) with medical treatment.

Methods

Prospective interventional cohort study of 28 eyes of 28 subjects in a tertiary eye care centre in India in patients with open-angle glaucoma. All enrolled eyes underwent ultrasound cycloplasty with the second-generation probe with six shots of 8 s each, operated by a single surgeon between November 2018 and January 2020. They were followed up for a period of 12 months. The primary treatment outcome was IOP and the secondary outcomes were vision and postoperative complications.

Results

A total of 28 eyes of 28 patients were studied, and the mean age was 63.82 ± 6.46 years. Primary open-angle glaucoma (75%) was the most common etiology. There was significant reduction in IOP from the baseline (24.93 ± 4.27 mmHg) to the postoperative value (15.82 ± 3.14 mmHg) at the end of 12 months (P < 0.00001). Mean reduction in IOP was 9.14 ± 4.09 mmHg at 12 months (36.66%). Number of ocular hypotensives reduced significantly from baseline (3.32 ± 0.47) to 12-month postoperative follow-up (0.68 ± 0.74) (P < 0.00001). Qualified success was achieved in 89.28% eyes. No major complications were noted.

Conclusion

Ultrasound cycloplasty is found to be effective and safe in eyes with open-angle glaucoma because of the primary or secondary etiology, being more effective in the former.

Ultrasound ciliary plasty in glaucoma treatment: A long‐term follow‐up study

PURPOSE

The present study aimed to evaluate the efficacy and safety of ultrasound ciliary plasty (UCP) in patients with open-angle glaucoma for three consecutive years.

METHODS

Sixty-one patients (62 eyes) with primary and secondary glaucoma were enrolled to undergo UCP. The primary outcome measures were intraocular pressure (IOP) reduction, success rates, glaucoma medication use and visual acuity after UCP. An IOP reduction of 20% compared to the baseline value without re-intervention was considered a successful treatment. Complete success was defined as cessation of antiglaucoma medications. Secondary outcome measures included intraoperative and postoperative complications. Measurements were performed preoperatively and at the first week, and 1, 3, 6, 12, 18, 24, 30 and 36 months postoperatively.

RESULTS

A total of 41 patients (41 eyes) were evaluated 36-month after UCP. The mean ± SD values of IOP preoperatively at 1 day, 1 week, 1; 3; 6; 12; 18; 24; 30 and 36 months postoperatively were 22.7 ± 5.0 mmHg, 17.1 ± 4.2 mmHg (p < 0.001), 15.7 ± 4.8 mmHg (p < 0.001), 18.8 ± 4.8 mmHg (p < 0.001), 17.3 ± 3.7 mmHg (p < 0.001), 16.9 ± 3.2 mmHg (p < 0.001), 16.6 ± 2.7 mmHg (p < 0.001), 16.3 ± 3.0 mmHg (p < 0.001), 15.8 ± 3.4 mmHg (p < 0.001), 15.3 ± 2.1 mmHg (p < 0.001) and 16.3 ± 3.0 mmHg (p < 0.001), respectively. The mean IOP at the last follow-up was reduced by 28.5%. The qualified success rate was 64.0%. All patients at 36-month follow-up visit required the use of antiglaucoma medications - none of the patients achieved complete success. The decrease in the number of antiglaucoma medications was statistically significant at each follow-up visit compared to the baseline. Choroid detachment was observed in three patients (4.8%), while macular oedema was observed in three patients (4.8%) after the procedure. No other major intraoperative or postoperative complications occurred.

CONCLUSION

Ultrasound ciliary plasty seems to be an effective and well-tolerated method to reduce IOP in patients with refractory glaucoma. Further studies with a larger group are needed to confirm the efficacy of this procedure.

Acoustic Manipulation of Intraocular Particles

Various conditions cause dispersions of particulate matter to circulate inside the anterior chamber of a human eye. These dispersed particles might reduce visual acuity or promote elevation of intraocular pressure (IOP), causing secondary complications such as particle related glaucoma, which is a major cause of blindness. Medical and surgical treatment options are available to manage these complications, yet preventive measures are not currently available. Conceptually, manipulating these dispersed particles in a way that reduces their negative impact could prevent these complications. However, as the eye is a closed system, manipulating dispersed particles in it is challenging. Standing acoustic waves have been previously shown to be a versatile tool for manipulation of bioparticles from nano-sized extracellular vesicles up to millimeter-sized organisms. Here we introduce for the first time a novel method utilizing standing acoustic waves to noninvasively manipulate intraocular particles inside the anterior chamber. Using a cylindrical acoustic resonator, we show ex vivo manipulation of pigmentary particles inside porcine eyes. We study the effect of wave intensity over time and rule out temperature changes that could damage tissues. Optical coherence tomography and histologic evaluations show no signs of damage or any other side effect that could be attributed to acoustic manipulation. Finally, we lay out a clear pathway to how this technique can be used as a non-invasive tool for preventing secondary glaucoma. This concept has the potential to control and arrange intraocular particles in specific locations without causing any damage to ocular tissue and allow aqueous humor normal outflow which is crucial for maintaining proper IOP levels.

Development of a Numerical Model of High-Intensity Focused Ultrasound Treatment in Mobile and Elastic Organs: Application to a Beating Heart

High-intensity focused ultrasound (HIFU) is a promising method used to treat cardiac arrhythmias, as it can induce lesions at a distance throughout myocardium thickness. Numerical modeling is commonly used for ultrasound probe development and optimization of HIFU treatment strategies. This study was aimed at describing a numerical method to simulate HIFU thermal ablation in elastic and mobile heart models. The ultrasound pressure field is computed on a 3-D orthonormal grid using the Rayleigh integral method, and the attenuation is calculated step by step between cells. The temperature distribution is obtained by resolution of the bioheat transfer equation on a 3-D non-orthogonally structured curvilinear grid using the finite-volume method. The simulation method is applied on two regions of the heart (atrioventricular node and ventricular apex) to compare the thermal effects of HIFU ablation depending on deformation, motion type and amplitude. The atrioventricular node requires longer sonication than the ventricular apex to reach the same lesion volume. Motion considerably influences treatment duration, lesion shape and distribution in cardiac HIFU treatment. These results emphasize the importance of considering local motion and deformation in numerical studies to define efficient and accurate treatment strategies.

Effect of high-intensity focused ultrasound (HiFU) treatment on intraocular pressure and aqueous humour dynamics: 12 -months results

PURPOSE

High intensity focused ultrasound (HiFU) is a cyclodestructive therapy for controlling intraocular pressure (IOP) in glaucoma. The mechanism of action is thought to be through destruction of the ciliary epithelium as well as increased uveoscleral outflow. We reviewed the change in aqueous humour dynamics parameters including aqueous humour flow rate, tonographic outflow facility (TOF) and uveoscleral outflow at 12 months.

PATIENTS AND METHODS

This is a prospective observational study. Consecutive patients with open angle glaucoma (OAG) or ocular hypertension (OHT) requiring further IOP lowering were enroled in the study between August 2016 and January 2017. Patients were commenced on medication washout period prior to baseline and twelve months' visit.

RESULTS

Sixteen patients (OAG) in the treatment group underwent assessment at twelve months follow up. Mean age was 63.1 ± 11 years. Eleven patients were African/Caribbean and 5 were Caucasian. Nine patients were female and 7 were male. Mean post-washout IOP was reduced by 21% (28.3 ± 5.7 at baseline vs 22.4 ± 8.4 mmHg at 12 months, p = 0.04). Aqueous humour flow rate was reduced by 16% at twelve months (2.40 ± 0.6 at baseline vs 2.02 ± 0.6 µl/min at 12 months, p = 0.0493). There was no statistically significant change in the TOF (0.12 ± 0.09 at baseline vs 0.08 ± 0.05 µl/min/mmHg at 12 months, p = 0.08) or uveoscleral outflow (0.6 ± 1.3 at baseline vs 1.3 ± 0.85 µl/min at 12 months, p = 0.15).

CONCLUSION

In this study, we demonstrated that the observed IOP reduction was likely due to aqueous humour flow rate reduction. The TOF and uveoscleral outflow were not detectibly changed.

Efficacy and Safety of Ultrasound Cycloplasty for Refractory Glaucoma: A 3-Year Study

PRECIS

Ultrasound cycloplasty (UCP) treatment using high-intensity focused ultrasound is an effective and safe therapy to reduce intraocular pressure (IOP) in patients with refractory glaucoma over a 3-year period.

PURPOSE

The purpose of this study was to evaluate the 3-year efficacy and safety of UCP in patients with refractory glaucoma.

PATIENTS AND METHODS

In all, 104 patients with refractory glaucoma recruited from 2 university hospitals underwent UCP. Examinations were performed 7 days, 1 week, 1, 3, 6, 12, 24, and 36 months after the UCP procedure. Primary outcomes were therapeutic success at 3 years (IOP reduction from baseline ≥20% and IOP >5 mm Hg without other surgical procedures) and vision-threatening complications. Secondary outcomes included mean IOP change from baseline at each follow-up visit, medication use, complications, and subsequent UCP and/or other postsurgical interventions.

RESULTS

At 3 years post-UCP, the therapeutic success rate was 55%. For 75% of the patients, results were obtained with only one procedure. For the overall study population, IOP was reduced significantly (P<0.005) from 27.6±8.9 mm Hg (n=3.0 topical hypotensive medication) to 17.0±6.8 mm Hg at 36 months (n=2.8 topical hypotensive medication) (33% reduction). For the success patients, the IOP was initially 29.3±8.8 mm Hg (n=3.0 topical hypotensive medication) and 15.6±4.3 mm Hg at 36 months (n=2.8 topical hypotensive medication) (43% reduction). The rate of complications was low and there were no cases of phthisis.

CONCLUSION

The UCP procedure was efficacious with few complications and should be considered as an alternative to other IOP-lowering therapies including laser cyclocoagulation in patients with refractory glaucoma.

Ultrasound cycloplasty in Chinese glaucoma patients: Results of a 6-month prospective clinical study

PURPOSE

The aim of this study was to evaluate the short-term efficacy and safety of ultrasound cycloplasty (UCP) procedure in Chinese glaucoma patients.

METHODS

As a single-centre, prospective, non-comparative study, 23 eyes of 23 patients suffering from glaucoma with uncontrolled intraocular pressure (IOP) ≥ 21 mmHg underwent a multi-dose UCP treatment with the activations of 6, 8 or10 sectors. Types of glaucoma include primary open-angle glaucoma (POAG) (7/23), primary angle closure glaucoma (PACG) (9/23) and secondary glaucoma (SG) (7/23). A complete ophthalmic examination including intraocular pressure (IOP) measurements was performed before UCP procedure and at 1 day, 1 month, 3months and 6 months after the procedure. An IOP reduction of ≥20% and IOP > 5 mmHg without increasing hypotensive medication at the follow-up visit was defined as therapeutic success. The post-operative complications were also recorded and compared to baseline for safety evaluation.

RESULTS

The mean baseline IOP of 23 treated eyes was 37.2 ± 12.1 mmHg. The IOP reduction after UCP procedure were 23%, 49%, 33% and 34% at 1 day, 1 month, 3 months and 6 months, respectively. Thus, the corresponding overall therapeutic success rates reached 61% (14/23), 83% (19/23), 65% (15/23) and 61% (14/23), respectively. Baseline IOPs of 8 and 10 sectors group (37.0 ± 9.9 mmHg and 50.1 ± 12.2 mmHg) were significantly higher than that of 6 sectors group (30.1 ± 8.2 mmHg). Therapeutic success rates of 6, 8 and 10 sectors groups reached 44% (4/9), 56% (5/9) and 100% (5/5), respectively. There were the highest percentage of IOP reduction (50% and 41%) and therapeutic success rate (6/7; 86% and 7/9; 78%) in SG group and PACG groups respectively. In addition, pre-operative ocular pain symptoms of four patients were all disappeared within one week after UCP. No serious intra-operative or post-operative complications occurred.

CONCLUSION

UCP procedure is an effective and well-tolerated treatment to reduce IOP in Chinese glaucoma patients, which offered a novel alternative for glaucoma treatment.

Assessment of Scleral and Conjunctival Thickness of the Eye after Ultrasound Ciliary Plasty

PURPOSE

This study aims to assess scleral and conjunctival thickness using optical coherence tomography after ultrasound ciliary plasty (UCP) procedure with reference to scleral marks appearing in the area where the ultrasound energy was applied.

MATERIALS AND METHODS

Seventy-eight patients with primary and secondary refractory glaucoma participated in this study. Complete ophthalmic examinations including measurements of scleral and conjunctival thickness were performed preoperatively and at 1 week, and 1, 3, 6, 12, 18, and 24 months postoperatively. The parameters were determined using the Swept Source OCT with anterior attachment. Thirty-eight patients (58 scleral marks-23 superior and 35 inferior) fulfilled the inclusion criteria and completed the follow-up period of 24 months.

RESULTS

The mean ± SD scleral and conjunctival thickness in superior scleral mark before the procedure and at 1 week, and 1, 3, 6, 12, 18, and 24 months after the procedure was 684.57 ± 83.58 μm, 771.78 ± 112.03 μm (p < 0.001), 771.74 ± 100.12 μm (p < 0.001), 731.38 ± 83.92 μm (p=0.012), 719.52 ± 73.20 μm (p=0.037), 702.91 ± 66.50 μm (p=0.247), 694.13 ± 72.22 μm (p=0.482), and 699.35 ± 70.68 μm (p=0.200), respectively. The mean ± SD scleral and conjunctival thickness in inferior scleral mark before the procedure and at 1 week, and 1, 3, 6, 12, 18, and 24 months after the procedure was 816.86 ± 79.30 μm, 936.37 ± 107.33 μm (p < 0.001), 946.00 ± 130.40 μm (p < 0.001), 896.63 ± 123.40 μm (p < 0.001), 877.69 ± 114.38 μm (p=0.003), 843.03 ± 71.55 μm (p=0.021), 811.86 ± 68.91 μm (p=0.731), and 805.03 ± 69.52 μm (p=0.248), respectively. The transient thickening of the sclera was observed after the procedure; however, after 12 months postoperatively, the parameters returned to the initial value and no significant difference was noted.

CONCLUSION

The sclera thickness increases after UCP. However, with time the thickness reduces to its initial value with no significant difference. Clinical implication of the scleral changes lasts shorter than the measured significant difference in scleral thickness.

Efficacy and safety of high-dose ultrasound cyclo-plasty procedure in refractory glaucoma

AIM

To evaluate the efficacy and safety of high-dose ultrasound cyclo-plasty (UCP) for the treatment of refractory glaucoma in Chinese patients.

METHODS

In this 6-month retrospective study, 37 eyes of 37 patients suffering from severe glaucoma with uncontrolled intraocular pressure (IOP) of ≥21 mm Hg underwent 8-s ultrasonic cyclocoagulation with ten active piezoelectric elements. A complete ophthalmic examination was performed before and at 1d, 1, 3, 6mo after UCP. Therapeutic success was defined as IOP reduction from baseline ≥20% and IOP ≥5 mm Hg without adding new glaucoma medication compare to baseline at the 6-month follow-up visit. In addition to mean IOP at each follow-up visit, medications used and complications were also detected and compared to baseline.

RESULTS

After UCP procedure, the mean IOP was significantly reduced (P<0.01) from the preoperative 44.1±11.9 mm Hg to postoperative 26.7±11.8 mm Hg at 3mo, and 30.4±14.5 mm Hg at 6mo. The overall mean IOP reductions achieved at 3 and 6mo were 39% and 31% compared to baseline IOP. Sixty-one percent of patients responded well to UCP treatment with a mean IOP reduction of 48% at 3mo and 42% at 6mo. Ocular pain in most of patients were alleviated. No serious intraoperative or postoperative complications occurred.

CONCLUSION

High-dose UCP treatment is an effective and safe procedure to reduce IOP in Chinese patients with severe glaucoma.

The Effect of High-Intensity Focused Ultrasound on Aqueous Humor Dynamics in Patients with Glaucoma

PURPOSE

To investigate the effects of high-intensity focused ultrasound (HiFU) on aqueous humor dynamics in patients with glaucoma.

DESIGN

Comparative, nonrandomized, interventional study.

PARTICIPANTS

Adult patients with a diagnosis of open-angle glaucoma or ocular hypertension with suboptimal intraocular pressure (IOP) control despite maximum medical treatment who required further IOP optimization.

METHODS

All patients underwent comprehensive ophthalmic examination before aqueous humor dynamics study measurements, including fluorophotometry and digital Schiøtz tonography. All patients received 6 seconds of HiFU therapy. Aqueous humor dynamics studies were repeated 3 months after the treatment (patients had 4-week washout from their glaucoma medication before their aqueous humor dynamics study measurements at baseline and the 3-month visit).

MAIN OUTCOME MEASURES

Intraocular pressure, facility of topographic outflow, aqueous flow rate, and uveoscleral outflow.

RESULTS

Thirty eyes of 30 patients were included in the study. At the 3-month postoperative visit, the mean postwashout IOP was reduced by 16% (31.7±5.3 vs. 26.6±4.8 mmHg, P = 0.004), and aqueous flow rate was decreased by 15% (2.07±0.73 vs. 1.77±0.55 μl/min, P = 0.05) from baseline. Neither the tonographic outflow facility nor the uveoscleral outflow was significantly different from baseline. There is a 20% risk of treatment failure (those who needed further glaucoma surgical intervention) within 1 month after a single HiFU treatment (n = 6). Only 25 patients (80%) were able to undergo post-treatment washout measurements, and in these eyes, only 26.6% of eyes achieved >20% IOP reduction at 3 months compared with baseline.

CONCLUSIONS

We investigated the aqueous humor dynamics effects of a cyclodestructive procedure and specifically HiFU in patients with uncontrolled open-angle glaucoma on maximum tolerated medical therapy. High-intensity focused ultrasound reduced IOP 3 months postoperatively by 16% and aqueous flow decreased by 15% without any significant effect on tonographic outflow facility and uveoscleral outflow.

The Influence of Ultrasound Ciliary Plasty on Corneal Parameters

PRéCIS:: The ultrasound ciliary plasty (UCP) procedure affects corneal parameters, although the effect is transient. Ultrasound energy affects the sclera, leading to induced astigmatism. The area of energy application correlates with the astigmatism axis.

PURPOSE

To assess the postoperative corneal topography for 1 year after UCP.

MATERIALS AND METHODS

In total, 78 patients with primary and secondary refractory glaucoma were enrolled in the study. The primary outcome measures were the corneal parameters obtained with anterior segment swept-source optical coherence tomography. Intraocular pressure, number of antiglaucoma medications, and best-corrected logMAR visual acuities were analyzed as secondary outcome measures. Measurements were performed preoperatively and at 1 week, and 1, 3, 6, and 12 months postoperatively. A total of 39 patients (39 eyes) completed the follow-up period of 12 months.

RESULTS

There was a significant difference in the anterior/posterior steep/flat keratometry and anterior/posterior astigmatism values immediately after UCP. However, 3 months postoperatively these parameters returned to their initial values and there were no significant differences noted. The mean±SD values of anterior astigmatism preoperatively and at 1 week, and 1, 3, 6, and 12 months postoperatively were 1.12±0.66 D, 2.17±0.91 D (P<0.001), 2.05±0.93 D (P<0.001), 1.55±0.75 D (P=0.004), 1.31±0.70 D (P=0.024), and 1.20±0.73 D (P=0.406), respectively. The astigmatism axis tended to approach 90 degrees meridian with a significant difference 1 week postoperatively. Central and minimal corneal thickness remained unchanged, whereas the intraocular pressure and the number of antiglaucoma medications decreased significantly.

CONCLUSIONS

UCP influenced the corneal topography parameters in the immediate postoperative period; however, with time, all parameters returned to their initial values.

Efficacy and safety of ultrasonic circular cyclocoagulation with second-generation probe in glaucoma: A retrospective study

Background

To assess the efficacy and safety of the second-generation probe of ultrasonic circular cyclocoagulation (UC3) in naive or refractory glaucoma, with a 6-month follow-up.

Methods

A retrospective consecutive case-series study included patients having a UC3 procedure with the second-generation probe of the EyeOP1 device, intraocular pressure (IOP) ≥ 21 mmHg and under maximum tolerated medical treatment, with or without previous glaucoma surgery. Surgical success was defined at the 6-month post-operative visit as IOP > 5 and ≤ 21 mmHg with IOP reduction ≥ 20% from baseline, without any reoperation, and visual acuity better than negative light perception.

Results

100 patients were included and 97 (97.0%; 97 eyes) attended the 6-month follow-up. At 6 months, surgical success was obtained in 48 eyes (49.5%). Intraocular pressure was reduced from a mean ± SD preoperative value of 28.0 ± 5.6 mmHg to 19.3 ± 7.1 mmHg at 6 months (p<0.0001). The proportion of eyes requiring oral acetazolamide decreased from 57.0% to 30.0% between baseline and 6 months after surgery (p = 0.0007). We observed 15 (15.0%) cases of postsurgical macular edema, 8 (8.0%) of hypotony, and 20 (20.0%) of visual acuity loss > 2 Snellen lines. Postsurgical macular edema was associated with a history of epiretinal membranes, uveitis or retinal detachment. Risk factors for hypotony were a history of diabetes or trabeculectomy.

Conclusions

The second-generation UC3 probe significantly reduced IOP in eyes with naive and refractory glaucoma but severe post-operative complications were often observed. Further studies are needed to better identify responders and decrease the high risk for complications associated with the procedure.

Efficacy and Safety of Repeated Ultrasound Cycloplasty Procedures in Patients With Early or Delayed Failure After a First Procedure

PRECIS

Repeated ultrasound cycloplasty (UCP) procedures are valuable options in patients with early or delayed intraocular pressure (IOP) increase after a first procedure. The safety of a second procedure is similar to that of the first one.

PURPOSE

The purpose of this study was to evaluate the efficacy and safety of repeated UCPs in patients with early or delayed IOP increase after a first procedure.

PATIENTS AND METHODS

Thirty-one eyes with open-angle glaucoma, with an IOP decrease,>20% after a first UCP procedure (1 and/or 2 mo visit), and with an early or delayed IOP increase (IOP decrease<20% compared with baseline before or after the first 6 mo, respectively), underwent a second UCP procedure. Examinations were performed at 1 day, 1 week, 1, 2, 3, 6, and 12 months. Primary outcomes were surgical success (IOP reduction≥20% and IOP>5 mm Hg) at the last follow-up and vision-threatening complications. Secondary outcomes were mean IOP at each visit, medication use, and other surgical interventions.

RESULTS

In the group with early IOP increase, IOP was reduced (P<0.05) from a mean value of 29.8±8.2 mm Hg before retreatment (n=3.3 medications) to 18.5±7.4 mm Hg at the last follow-up (n=3.5 medications) (-34%). Success was achieved in 52.6% of eyes (10/19) at the last follow-up visit. In the late IOP increase group, IOP was reduced (P<0.05) from a mean value of 31.9±6.6 mm Hg before retreatment (n=4.0 medications) to 16.2±5.2 mm Hg at the last follow-up (n=4.0 medications) (-43%). Success was achieved in 55.5% of eyes (5/9) at the last follow-up visit. No major intraoperative or postoperative complications occurred.

CONCLUSION

A second UCP procedure could be considered in subjects with early or delayed failure after a first procedure.

Cyclodestructive Procedures in Glaucoma: A Review of Current and Emerging Options

The first surgical modalities to reduce aqueous humor production by damaging the ciliary body date back to the early twentieth century. Until recently, however, cyclodestructive procedures (e.g., cyclocryotherapy and transscleral diode laser photocoagulation) have been reserved as last option procedures in refractory glaucoma patients with poor visual potential. Emerging technologic innovation has led to the development of promising, safer and less destructive techniques, such as micropulse diode cyclophotocoagulation, endoscopic cyclophotocoagulation and ultrasound cyclodestruction. Consequently, an emerging paradigm shift is under way with the selection of these surgical options in eyes with less severe glaucoma and good visual potential. Although existing evidence has not, as yet, adequately defined the role and value of these procedures, their emergence is a welcome expansion of available options for patients with moderate-to-severe glaucoma. This article reviews the pertinent evidence on both established and evolving cyclodestructive techniques and describes their growing role in the management of glaucoma.

Short-Term Observation of Ultrasonic Cyclocoagulation in Chinese Patients with End-Stage Refractory Glaucoma: A Retrospective Study

Purpose

To assess the efficacy and safety of HIFU-based ultrasonic cyclocoagulation in Chinese patients with end-stage refractory glaucoma.

Method

Patients were recruited consecutively from May 2016 to May 2017 in the Zhongshan Ophthalmic Center. Ultrasonic cyclocoagulation was performed on every patient, using the EyeOP1 ultrasound emitting device. Return visits were set at 1 day, 7 days, 1 month, and 3 months after the treatment. An intraocular pressure (IOP) reduction of ≥20% while IOP ≥ 5 mmHg was deemed as success. Mean IOP change was assessed. Efficacy of two modes (6 sectors and 8 sectors) was also compared. Complications were recorded for safety evaluation.

Results

61 eyes were treated in this study. The baseline IOP (mean ± SD) was 41.11 ± 10.65 mmHg. The percentage of IOP reduction after treatment was 29.2%, 43.2%, 34.8%, and 23.1% at 1 day, 7 days, 1 month, and 3 months, respectively. Overall success rate at 3 months was 50.0% (26/52). No significant difference was found between the 6 sectors group and the 8 sectors group in terms of the success rate (48.6% vs. 52.9%, p=0.768) as well as IOP reduction (p=0.417) at 3 months. Primary angle-closure glaucoma (PACG) had the highest success rate (80.0%, 12/15). Scleral thinning existed in 12 eyes, among which 2 developed hypotony (2 mmHg and 3 mmHg). Average pain score decreased massively compared with baseline data.

Conclusion

With high percentage of IOP reduction and a good safety profile observed in our study, HIFU-based ultrasonic cyclocoagulation might become a promising alternative to cyclodestructive methods. Long-term efficacy and safety need further assessment. The study was registered with Chinese Clinical Trial Registry (http://www.chictr.org.cn; Registration number: ChiCTR-OOC-17014028).

High intensity focused ultrasound cyclocoagulation in dogs with primary glaucoma: a preliminary study

The objective was to assess the effect of high intensity focused ultrasound (HIFU) on intraocular pressure (IOP) in dogs with primary glaucoma (PG). Seven dogs (13 eyes) presenting with PG as diagnosed by a raised IOP (> 20 mm Hg) associated with consistent gonioscopy and ultrasound biomicroscopy of the ciliary cleft, with no other ocular disease. Patients were divided into 3 groups, corresponding to their pre-operative IOP (group 1 ranging from 21 to 30 mm Hg, group 2 from 31 to 40 and group 3 for 40 and above). Ciliary process sonication was achieved with a probe containing one high-frequency transducer operating at 21 MHz during 5 seconds. Six sites were treated in patients from group 1, 8 in group 2, 10 in group 3, under general anesthesia. Post-operative treatment consisted of systemic meloxicam and topical carbonic anhydrase inhibitors, beta-blockers and prostaglandins analogues. No intraoperative complications were observed. Conjunctival hyperaemia occurred in eyes from group 2 (66%) and 3 (100%). Conjunctival burns were visible in 2 patients from group 3. One patient from group 3 experienced a hypertensive spike during the first hours post-op with associated pain. The hypotensive effect of HIFU was observed in all groups. Normotensive IOP (≤20 mm Hg) was reached in all patients until the last recheck at 6 months post op. Despite the small number of patients included in the study, HIFU appears to be a promising option for the management of PG in dogs.

Ultrasound Cyclo Plasty in Eyes with Glaucoma

Glaucoma is a chronic disease caused by the progressive degeneration of the optical nerve fibers, resulting in decreased visual field that can lead to severe visual impairment, and eventually blindness. This manuscript describes a simple, surgeon-friendly, non-incisional technique, named Ultrasound Cyclo Plasty (UCP), for reducing intraocular pressure (IOP) in glaucoma patients. The technique determines a selective coagulation necrosis of the ciliary body; in addition, the stimulation of supra-choroidal and trans-scleral portions of the uveo-scleral outflow pathway has been recently proposed. UCP shows several technical improvements in ultrasound technology compared to previous techniques, providing more precise focusing on the target zone. The procedure is performed in the operating room under peribulbar anesthesia. Briefly, the coupling cone is put in contact with the eye and the ring probe, that contains six piezoelectric transducers which produce the ultrasound beams, is inserted inside it. Their proper centering over the ocular surface represents a crucial step for the correct targeting of the ciliary body. Sterile balanced salt solution is used to fill the empty spaces to ensure ultrasound acoustic propagation. Surgical treatment consists in the sequential automatic activation of each of the six transducers, for a total duration of less than 3 min. The patient leaves the hospital 1 h after the procedure with the treated eye patched. In the present study, 10 patients with open-angle glaucoma were followed-up during at least 12 months after the procedure. IOP was reduced at each interval compared to pre-operative, as well as the number of hypotensive medications. Twenty percent of patients did not respond to the treatment, and needed subsequent surgery to better control IOP. Treatment tolerability was good, with no cases of hypotony or phthisis. The UCP procedure is simpler, faster, safer, and less invasive than traditional cyclodestructive procedures with similar results in reducing IOP.

High-intensity Focused Ultrasound Cycloplasty: Analysis of Pupil Dynamics

Aim

High-intensity focused ultrasound cystoplasty (UCP) aims to noninvasively and selectively target the ciliary body, thus lowering intraocular pressure (IOP). To be used on a large scale, the safety of the UCP procedure should be studied. Therefore, its effect on pupil behavior is important to better inform patients and to help physicians predict possible treatment side effects. This study aimed to evaluate to what extent UCP procedure (EyeOP-1®) affects pupil dynamics.

Materials and methods

Consecutive glaucoma patients with uncontrolled IOP despite optimal medication scheduled for UCP treatment were recruited and followed for 6 months. Pupillometry (PlusoptiX^® S0₄) was performed at baseline, and 1, 3 and 6 months after UCP procedure at scotopic and mesopic conditions. The difference between pupil diameter (PD) in both lighting conditions was calculated at the three follow-up visits. Demographic, clinical characteristics and specific ocular parameters (anterior chamber depth and volume, white-to-white measurement, axial length, phakic status) were registered. Statistical analysis was performed using STATA 14.1.

Results

Sixteen eyes of 16 patients with a mean age of 69 ± 11 years were included. Mean preoperative IOP and number of medications were 23.6 ± 3.0 mm Hg and 2.4 ± 1.3, respectively. Mean baseline scotopic and mesopic PD were 4.8 ± 0.8 mm and 4.4 ± 0.9 mm, respectively (difference = 0.38 ± 0.30 mm; range 0.1 to 1.2 mm). At month-1, the pupil diameter (PD) change between scotopic (4.6 ± 0.7 mm) and mesopic (4.5 ± 0.8 mm) conditions decreased to 0.03 ± 0.34 mm, p = 0.01. On the longer follow-up periods, however, the amplitude difference in PD compared to baseline was no longer significant (month-3: 0.28 ± 0.49 mm; month 6: 0.23 ± 0.41 mm; p >0.05). At the end of follow-up, mean scotopic and mesopic PD were 4.7 ± 1.0 mm and 4.4 ± 0.9 mm, respectively.

Conclusion and clinical significance

In the early postoperative period after UCP treatment, most patients present with a less light-reactive pupil, which seems to normalize with time.

How to cite this article

Sousa DC, Ferreira NP, Marques-Neves C, Somers A, Vandewalle E, Stalmans I, Pinto LA. High-intensity Focused Ultrasound Cycloplasty: Analysis of Pupil Dynamics. J Curr Glaucoma Pract 2018;12(3):102-106.

Multicenter clinical trial of high-intensity focused ultrasound treatment in glaucoma patients without previous filtering surgery

PURPOSE

To evaluate the efficacy and safety of the ultrasonic circular cyclocoagulation procedure in patients with open-angle glaucoma naïve of previous filtering surgery.

METHODS

Prospective non-comparative interventional clinical study conducted in five French University Hospitals. Thirty eyes of 30 patients with open-angle glaucoma, intra-ocular pressure (IOP) > 21 mmHg and with no previous filtering glaucoma surgeries were sonicated with a probe comprising six piezoelectric transducers. The six transducers were activated with a 6-s exposure time. Complete ophthalmic examinations were performed before the procedure and at 1 day, 1 week, 1, 2, 3, 6 and 12 months after the procedure. Primary outcomes were qualified surgical success (defined as IOP reduction from baseline ≥20% and IOP > 5 mmHg with possible re-intervention and without hypotensive medication adjunction) and complete surgical success (defined as IOP reduction from baseline ≥20%, IOP > 5 mmHg and IOP < 21 mmHg with possible re-intervention and without hypotensive medication adjunction) at the last follow-up visit and vision-threatening complications. Secondary outcomes were mean IOP at each follow-up visit compared with baseline, medication use, complications and re-interventions.

RESULTS

Intra-ocular pressure was significantly reduced (p < 0.05) from a mean pre-operative value of 28.2 ± 7.2 mmHg (n = 3.6 hypotensive medications) to 19.6 ± 7.9 mmHg at 12 months (n = 3.1 hypotensive medications and n = 1.1 procedures) (mean IOP reduction of 30%). Qualified success was achieved in 63% of eyes (19/30) (mean IOP reduction of 37% in these eyes) and complete success in 46.7% of eyes (14/30) (mean IOP reduction of 37% in these eyes) at the last follow-up. No major intra- or post-operative complications occurred.

CONCLUSIONS

The UC(3) procedure seems to be an effective and well-tolerated method to reduce IOP in patients with open-angle glaucoma without previous filtering surgery.

Thermal safety of ultrasound-enhanced ocular drug delivery: A modeling study

PURPOSE

Delivery of sufficient amounts of therapeutic drugs into the eye for treatment of various ocular diseases is often a challenging task. Ultrasound was shown to be effective in enhancing ocular drug delivery in the authors' previous in vitro and in vivo studies.

METHODS

The study reported here was designed to investigate the safety of ultrasound application and its potential thermal effects in the eye using PZFlex modeling software. The safety limit in this study was set as a temperature increase of no more than 1.5 °C based on regulatory recommendations and previous experimental safety studies. Acoustic and thermal specifications of different human eye tissues were obtained from the published literature. The tissues of particular interest in this modeling safety study were cornea, lens, and the location of optic nerve in the posterior eye. Ultrasound application was modeled at frequencies of 400 kHz-1 MHz, intensities of 0.3-1 W/cm(2), and exposure duration of 5 min, which were the parameters used in the authors' previous drug delivery experiments. The baseline eye temperature was 37 °C.

RESULTS

The authors' results showed that the maximal tissue temperatures after 5 min of ultrasound application were 38, 39, 39.5, and 40 °C in the cornea, 39.5, 40, 42, and 43 °C in the center of the lens, and 37.5, 38.5, and 39 °C in the back of the eye (at the optic nerve location) at frequencies of 400, 600, 800 kHz, and 1 MHz, respectively.

CONCLUSIONS

The ocular temperatures reached at higher frequencies were considered unsafe based on current recommendations. At a frequency of 400 kHz and intensity of 0.8 W/cm(2) (parameters shown in the authors' previous in vivo studies to be optimal for ocular drug delivery), the temperature increase was small enough to be considered safe inside different ocular tissues. However, the impact of orbital bone and tissue perfusion should be included in future modeling efforts to determine the safety of this method in the whole orbit especially regarding potential adverse optic nerve heating at the location of the bone.

Keratorefractive Effect of High Intensity Focused Ultrasound Keratoplasty on Rabbit Eyes

Purpose. To evaluate high intensity focused ultrasound (HIFU) as an innovation and noninvasive technique to correct presbyopia by altering corneal curvature in the rabbit eye. Methods. Eighteen enucleated rabbit eyes were treated with a prototype HIFU keratoplasty. According to the therapy power, these eyes were divided three groups: group 1 (1 W), group 2 (2 W), and group 3 (3 W). The change in corneal power was quantified by a Sirius Scheimpflug camera. Light microscopy (LM) and transmission electron microscopy (TEM) were performed to determine the effect on the corneal stroma. Results. In the treated eyes, the corneal curvature increases from 49.42 ± 0.30 diopters (D) and 48.00 ± 1.95 D before procedure to 51.37 ± 1.11 D and 57.00 ± 1.84 D after HIFU keratoplasty application in groups 1 and 3, respectively. The major axis and minor axis of the focal region got longer when the powers of the HIFU got increased; the difference was statistically significant (p < 0.05). LM and TEM showed HIFU-induced shrinkage of corneal stromal collagen with little disturbance to the underlying epithelium. Conclusions. We have preliminarily exploited HIFU to establish a new technique for correcting presbyopia. HIFU keratoplasty will be a good application prospect for treating presbyopia.

Trimodal Therapy: Combining Hyperthermia with Repurposed Bexarotene and Ultrasound for Treating Liver Cancer

Repurposing of existing cancer drugs to overcome their physical limitations, such as insolubility, represents an attractive strategy to achieve enhanced therapeutic efficacy and broaden the range of clinical applications. Such an approach also promises to offer substantial cost savings in drug development efforts. Here we repurposed FDA-approved topical agent bexarotene (Targretin), currently in limited use for cutaneous manifestations of T-cell lymphomas, and re-engineer it for use in solid tumor applications by forming self-assembling nanobubbles. Physico-chemical characterization studies of the novel prodrug nanobubbles demonstrated their stability, enhanced target cell internalization capability, and highly controlled release profile in response to application of focused ultrasound energy. Using an in vitro model of hepatocellular carcinoma and an in vivo large animal model of liver ablation, we demonstrate the effectiveness of bexarotene prodrug nanobubbles when used in conjunction with catheter-based ultrasound, thereby highlighting the therapeutic promise of this trimodal approach.

High-intensity focused ultrasound treatment in refractory glaucoma patients: results at 1 year of prospective clinical study

PURPOSE

To evaluate the safety and efficacy of the ultrasonic circular cyclo-coagulation procedure using high-intensity focused ultrasound by a miniaturized annular device containing 6 piezoceramic transducers in patients with refractory glaucoma.

METHODS

This was a prospective interventional noncomparative study of 20 eyes of 20 patients with refractory glaucoma. All eyes were treated with 6 activated transducers operating at 21 MHz. Ultrasound biomicroscopy and a complete ophthalmic examination were performed before the procedure and at 1 day, 1 week, and 1, 3, 6, and 12 months after the procedure. Primary outcomes were surgical success (defined as intraocular pressure (IOP) reduction from baseline ≥20% and IOP &gt;5 mm Hg) at the last follow-up visit. Secondary outcomes were mean IOP at each follow-up visit compared to baseline, medication use, complications, and re-interventions.

RESULTS

Intraocular pressure was significantly reduced (p&lt;0.01) from a mean preoperative value of 36.4 ± 5.7 mm Hg to a mean postoperative value of 22.5 ± 10.3 mm Hg at 12 months. Four patients needed to be re-treated. The mean IOP reduction achieved was 38%. Surgical success was achieved in 13 of 20 eyes (65%). No major intraoperative or postoperative complications occurred.

CONCLUSIONS

Ultrasonic circular cyclo-coagulation using high-intensity focused ultrasound delivered by a circular miniaturized device containing 6 piezoceramic transducers is an effective and well-tolerated method to reduce IOP in patients with refractory glaucoma.

Noninvasive glaucoma procedures: current options and future innovations

Noninvasive glaucoma procedures (NIGPs) represent a new dawn in the management of glaucoma. They try to fill the gap between the shortcoming of invasive glaucoma surgeries and antiglaucoma medications. NIGPs were introduced as an adjunct or alternative treatments for glaucoma. Some of these procedures have shown good efficacy with few serious complications. Hence, they are now used as both primary and adjunctive therapy for glaucoma. The most common NIGPS involve laser and ultrasound technologies. Currently, the portfolio of NIGPs includes argon laser trabeculoplasty, selective laser trabeculoplasty, and micropulse diode laser trabeculoplasty. More recent innovations include therapeutic ultrasound for glaucoma, ultrasonic circular cyclocoagulation, and deep wave trabeculoplasty.

Towards a dosimetric framework for therapeutic ultrasound

There is a need for a coherent set of exposure and dose quantities to describe ultrasound fields in media other than water (including tissue and tissue-simulating materials). This paper proposes an outline dosimetry scheme, with quantities for free field exposure, in situ exposure, dose (both instantaneous and cumulative) and effect, to act as a structure for organising a more complete set of definitions. It also presents findings from a survey of the views of the therapeutic ultrasound community which generally supports the principle of using modified free field quantities to describe the in situ field, and the prioritising of dose quantities which are related to heating and thermal mechanisms. Although there is no one-to-one relationship between any known ultrasound dose quantity and a specific biological effect, this can also be said of radiotherapy and other modalities where weighting factors have been developed to calculate the degree of equivalence between different tissues and radiation types. This same separation is recommended for ultrasound, provided that an appropriate set of recognised 'engineering' quantities can be established for exposure and dose quantities.

Bi-modal cancer treatment utilizing therapeutic ultrasound and an engineered therapeutic nanobubble

We developed a bi-modal cancer therapy comprising a sorafenib loaded ultra-sonic responsive nanobubble (SRF-NB) for ultrasonic assisted delivery in hepatocellular carcinoma.

Short- and long-term effects on the ciliary body and the aqueous outflow pathways of high-intensity focused ultrasound cyclocoagulation

Several physical methods can be used to coagulate the ciliary body and decrease intra-ocular pressure in patients with glaucoma. The study described here investigated the short- and long-term effects of high-intensity focused ultrasound (HIFU) cyclocoagulation on the aqueous humor production structures and outflow pathways. Thirty-four rabbit eyes were sonicated with a ring-shaped probe containing six miniaturized HIFU transducers. Light, scanning electron and transmission electron microscopy and corrosion casts were performed. In the affected regions, the epithelium of the ciliary processes was degenerated or necrotic and sloughed off. Examinations performed several months afterward revealed involution of the ciliary processes. Vascular corrosion cast revealed focal interruption of the ciliary body microvasculature. In most animals, a sustained fluid space was seen between the sclera, the ciliary body and the choroid, likely indicating an increase in the aqueous outflow by the uveoscleral pathway. These results suggest that HIFU cyclocoagulation has a dual effect on aqueous humor dynamics.

Treatment of refractory open-angle glaucoma using ultrasonic circular cyclocoagulation: a prospective case series

OBJECTIVE

To evaluate the efficacy and safety of the ultrasonic circular cyclocoagulation (UC(3)) procedure in patients with refractory primary open-angle glaucoma.

RESEARCH DESIGN AND METHODS

Prospective non-comparative interventional case series performed in two French glaucoma centers. Twenty-eight eyes of 28 patients with primary open-angle glaucoma, intraocular pressure (IOP) >21 mmHg, an average of 1.4 failed previous surgeries and an average of 3.8 hypotensive medications were insonified with a therapy probe comprising six piezoelectric transducers. The six transducers were activated and all patients were treated with a 6 second exposure time. Complete ophthalmic examinations were performed before the procedure, and at 1 day, 1 week, 1, 2, 3, 6 and 12 months after.

MAIN OUTCOME MEASURES

Primary outcomes were surgical success (defined as IOP reduction from baseline ≥20% and IOP >5 mmHg) at the last follow-up visit, and vision-threatening complications. Secondary outcomes were mean IOP at each follow-up visit compared to baseline, medication use, complications, and re-interventions.

RESULTS

IOP was significantly reduced (P < 0.05), from a mean preoperative value of 29.0 ± 7.2 mmHg (n = 3.8 hypotensive medications) to a mean value of 21.6 ± 9.4 mmHg at last follow-up (n = 3.8 hypotensive medications and n = 1.29 procedures) (mean IOP reduction of 26%). Complete success (IOP reduction >20% without re-intervention and without hypotensive medications adjunction) was achieved in 50% of eyes at last follow-up (mean IOP reduction of 45% in these same eyes) and qualified success (IOP reduction >20% with possible re-interventions) was achieved in 68% of eyes at last follow-up. No major intra- or post-operative complications occurred.

CONCLUSIONS

UC(3) procedure seems to be an effective and well tolerated method to reduce intraocular pressure in patients with primary open-angle glaucoma. Studies directly comparing the efficacy and safety of the UC(3) procedure with that of trabeculectomy or diode laser are needed.

Contribution of inertial cavitation in the enhancement of in vitro transscleral drug delivery

In ocular drug delivery, the sclera is a promising pathway for administering drugs to both the anterior and posterior segments of the eye. Due to the low permeability of the sclera, however, efficient drug delivery is challenging. In this study, pulsed ultrasound (US) was investigated as a potential method for enhancing drug delivery to the eye through the sclera. The permeability of rabbit scleral tissue to a model drug compound, sodium fluorescein, was measured after US-irradiation at 1.1 MHz using time-averaged acoustic powers of 0.5-5.4 W (6.8-12.8 MPa peak negative pressure), with a fixed duty cycle of 2.5% for two different pulse repetition frequencies of 100 and 1000 Hz. Acoustic cavitation activity was measured during exposures using a passive cavitation detector and was used to quantify the level of bubble activity. A correlation between the amount of cavitation activity and the enhancement of scleral permeability was demonstrated with a significant enhancement in permeability of US exposed samples compared to controls. Transmission electron microscopy showed no evidence of significant alteration in viability of tissue exposed to US exposures. A pulsed US protocol designed to maximum cavitation activity may therefore be a viable method for enhancing drug delivery to the eye.

NEW COMPUTATIONAL APPROACHES FOR BIOPHYSICAL HEAT TRANSFER IN TISSUE UNDER ULTRASONIC WAVES: THE VARIATIONAL ITERATION AND CHEBYSCHEV SPECTRAL SIMULATIONS

A mathematical and numerical study is presented for simulating temperature distribution in a two-dimensional tissue medium using Pennes bioheat transfer equation, when the tissue is subjected to ultrasonic waves. Following nondimensionalization of the governing partial differential equation, a novel variational iteration method (VIM) solution is developed. This excellent technique introduced by He [Variational iteration method — a kind of non-linear analytical technique: Some examples, Int J Non-Linear Mech.34:699–708, 1999] employs Lagrange multipliers which can be identified optimally via variational theory. The space and time distributions of temperature are studied and solutions visualized via Mathematica. The influence of thermal conductivity and relaxation time are also examined. Excellent stability and convergence characteristics of VIM are demonstrated. Validation is achieved with a Chebyschev spectral collocation method (CSCM). The present work demonstrates the excellent potential of this powerful semi-numerical method in nonlinear biological heat transfer and furthermore provides an alternative strategy to conventional finite element and finite difference computational simulations. The model finds applications in minimally-invasive spinal laser treatments, glaucoma therapy in ophthalmology and thermoradiotherapy for malignant tumors.

New clinical application of high-intensity focused ultrasound: local control of synovial sarcoma

High-intensity focused ultrasound (HIFU) is playing an increasingly important role in cancer therapy. Primary synovial sarcomas of the chest wall are extremely rare. We report the first case of noninvasive HIFU therapy for the control of synovial sarcoma. A 51-year-old man was diagnosed with spindle cell sarcoma on the left chest wall through lumpectomy. After four cycles of chemotherapy, local recurrence of the sarcoma was detected. Subsequent extended resection confirmed synovial sarcoma. After five cycles of a new chemotherapy option, the sarcoma relapsed again. Then the patient received five courses of HIFU; this completely ablated the sarcoma without complications. No chemotherapy, radiotherapy, or biological therapy has been applied since. Now the patient is stable and has a high quality of life.

Therapeutic applications of ultrasound in ophthalmology

Therapeutic ultrasound, although less well known than ultrasound for diagnostic imaging, has become a topic of growing interest in ophthalmology. High intensity focused ultrasound (HIFU) for the treatment of glaucoma and ultrasonic drug delivery are the two main areas of research and potential clinical applications. For the treatment of glaucoma, the specific advantage of HIFU, particularly when compared to the laser, is that the energy can be focused through optically opaque media, especially through the sclera which is a strongly light-scattering medium. HIFU is therefore a possible method for partial coagulation of the ciliary body (an anatomical structure responsible for the production of the liquid filling the eye) and, hence, reducing intraocular pressure and the risk of glaucoma. Ocular drug bioavailability also remains a challenge, being limited by multiple barriers to drug entry and lacrimal drainage, and making it difficult to achieve a sufficient drug concentration for numerous diseases of the front and back of the eye. As the front wall of the eye (cornea and anterior sclera) is a pathway for topically applied drugs, locally applied ultrasound has been proposed as a way of enhancing the delivery and activity of drugs and genes. Despite the fact that experimental studies seem to confirm the potential benefit of ultrasound ocular drug delivery, there is still a lack of clinical evidence. The aim of this contribution is to provide an update on recent advances in the field of therapeutic ultrasound in ophthalmology.