Micropulse laser for the treatment of glaucoma: A literature review

Micropulse Trans-scleral Cyclophotocoagulation in Patients With Glaucoma: 1- and 2-Year Treatment Outcomes

PRéCIS:: Micropulse trans-scleral cyclophotocoagulation (TSCPC) is an effective and safe IOP-lowering treatment for patients with primary or secondary glaucoma.

PURPOSE

To investigate the 1-year and 2-year effect on intraocular pressure (IOP) and safety profile of micropulse TSCPC in patients with glaucoma.

METHODS

Patients with glaucoma underwent a standardized micropulse TSCPC (MicroPulse P3 probe, Iridex cyclo G6 laser system, Mountain View, CA) at the University Eye Clinic Maastricht from November 2016 to May 2018. Patients with at least 12 months of follow-up were included.

RESULTS

A total of 141 eyes of 136 patients were included. The mean age was 67.2±14.5 years, and 56.6% of patients were male individuals. The glaucoma subtypes treated were primary glaucoma (n=99) and secondary glaucoma (n=42). Prior glaucoma surgery was performed in 59 of 141 eyes (41.8%). The mean preoperative IOP was 23.5±9.4 mm Hg. The mean postoperative IOP dropped to 16.8±8.4, 17.0±7.8, and 16.8±9.2 mm Hg, after 12, 18, and 24 months, respectively. The mean number of IOP-lowering medications used preoperatively was 3.3±1.4. The mean number of medications used at 12, 18, and 24 months was respectively 2.6±1.5, 2.5±1.4, and 2.2±1.5. Postoperative complications included cystic macular edema (n=2), hypotony maculopathy (n=1), fibrinous/uveitic reaction (n=1), and rejection of corneal graft (n=1), all reversible after treatment. One patient developed persisting hypotony in the late postoperative period.

CONCLUSIONS

Micropulse TSCPC is a safe and effective treatment for lowering both IOP and the number of IOP-lowering medications. Micropulse TSCPC can also be considered as a good alternative treatment option for patients after failed incisional glaucoma surgery or patients who are at high risk for incisional surgery.

Angle-closure glaucoma secondary to ciliary body cysts treated with subliminal transscleral cyclophotocoagulation. Report of a case

Angle-closure glaucoma secondary to ciliary body cysts is a rare condition. Different pharmacological and surgical treatment modalities have been described. Among these, subliminal transscleral cyclophotocoagulation is a promising alternative due to fewer ocular complications and the same intraocular pressure reducing efficacy. The case is presented of a 33-year-old woman with a 6-year history of uncontrolled ocular hypertension, and a one-month history of glaucoma, treated with multiple drugs and surgical interventions, with persistent elevated intraocular pressure. She came to the clinic due to eye pain and photophobia of the right eye of 3 days onset prior to her visit. An ultrasound biomicroscopy was performed, finding cysts in the ciliary body. It was then decided to perform subliminal transscleral cyclophotocoagulation, achieving a reduction in intraocular pressure, which was maintained after three months of follow-up.

The application of continuous wavelet transform based on spectrophotometric method and high-performance liquid chromatography for simultaneous determination of anti-glaucoma drugs in eye drop

In this study, a fast, low-cost, accurate, and precise spectrophotometric method based on the continuous wavelet transform (CWT) was assayed to determine dorzolamide (DOR) and timolol (TIM) in an eye drop sample simultaneously. Different wavelet families were investigated to select the best family for analyzing the DOR and TIM. The Mexican hat wavelet (MHW) family with the wavelength of 281 nm and Gaussian wavelet family (gaus2) in the wavelength of 267 nm were found for the simultaneous analysis of DOR and TIM, respectively. Mean recovery values of synthetic mixtures were found 97.44%±2.63 and 99.18%±4.00 for DOR and TIM, respectively. The root mean square errors (RMSE) of DOR and TIM were achieved 0.5550 and 0.3306, respectively. Eye drop as a real sample was analyzed by spectrophotometry coupled with the CWT technique, as well as high-performance liquid chromatography (HPLC) as a reference method. The obtained results were compared with each other by the one-way analysis of variance (ANOVA) test and there was no significant difference between them.

Histologic effects of MicroPulse™ transscleral cyclophotocoagulation in normal equine eyes

OBJECTIVE

Determine the immediate post-operative effects of MicroPulse^™ transscleral cyclophotocoagulation (MP-TSCPC) in healthy equine eyes.

ANIMALS STUDIED

Ten adult horses.

METHODS

MP-TSCPC was performed on sedated horses in 12 eyes (4 groups) using the following parameters (power, duration, duty cycle): (1) 2000 mW, 180 seconds, 31.3%; (2) 3000 mW, 180 seconds, 31.3%; (3) 3000 mW, 270 seconds, 31.3%; and (4) 3000 mW, 270 seconds, 50%. Three additional eyes were left untreated (control). Eyes were monitored clinically until euthanasia (mean = 3 hours post-procedure). Histologic sections were assessed with light microscopy and transmission electron microscopy (TEM).

RESULTS

MP-TSCPC was well tolerated by sedated horses. Adverse effects were only noted in Group 4: ocular hypertension (n = 3/3), conjunctival burns (3/3), aqueous flare (2/3), and a corneal erosion (1/3). Histologic scoring of Group 4 was statistically greater than other treated groups (1-3) and control eyes (P ≤ .021). TEM showed subtle changes to the mitochondria and plasma membrane infoldings of the basilar surface of the nonpigmented epithelium in all treated eyes.

CONCLUSIONS

MP-TSCPC does not cause immediate post-procedure adverse clinical effects or pronounced morphological changes to the ciliary body, except with the highest laser settings evaluated (power 3000 mW, duration 270 seconds, duty cycle 50%).

Micropulse Cyclophotocoagulation: A Multicenter Study of Efficacy, Safety, and Factors Associated With Increased Risk of Complications

PRéCIS:: Micropulse cyclophotocoagulation (MPCP) lowered intraocular pressure (IOP) in the short-term but nearly half required additional intervention. Mydriasis was the most common complication (11%); 15% lost ≥3 Snellen lines of acuity; 11% had persistent complications at last follow-up.

PURPOSE

The purpose of this study was to evaluate the efficacy and complications of MPCP in a large series of patients with all stages of glaucoma.

DESIGN

Multicenter, retrospective chart review of patients from 3 clinical sites.

PARTICIPANTS

One hundred sixty-seven eyes of 143 patients.

METHODS

MPCP was performed with 2000 mW energy, 31.3% duty cycle and 2 to 4 180-degree applications of 80 seconds duration each per treatment. The procedure was considered a failure if any of the following occurred: additional IOP lowering intervention, <20% IOP reduction from baseline at the last follow-up (with or without medication), or severe complications.

RESULTS

Mean age was 71 years, 53% were female, and 53% were Asian. 60% of eyes had POAG, 63% were pseudophakic, 38% had prior glaucoma surgery, and 51% had Snellen visual acuity (VA) of 20/40 or better. Mean follow-up time was 11.9±7.8 months. Mean IOP was 21.9±8.4 mm Hg before intervention, and 17.4±7.2 mm Hg at last follow-up (P<0.0001). There was no change in mean logMAR VA (P=0.0565) but 15% lost ≥3 Snellen lines of VA. The success rate was 36.5% (61/167 eyes) at last follow-up. The probability of survival by Kaplan-Meier analysis was 82%, 71%, and 57% at 3, 6, and 12 months after the procedure, respectively. The reasons for failure were additional intervention in 47%, inadequate IOP reduction in 14%, and severe complication in 1.8%. In a multivariable Cox proportional hazard model, female sex was associated with a 56% decrease in failure rate compared with males (P<0.0001), while a unit increase in baseline IOP corresponded with a 5.7% increase in failure rate (P<0.0001). If repeat MPCP was allowed then success rate increased to 58%. There were no complications in 73% (122/167) but 11% (18/167) had persistent complications at the last follow-up and half of these 18 eyes had decrease in VA of 1 to 6 Snellen lines. Asian race (odds ratio 13.5, P=0.0131) and phakic status (odds ratio 3.1, P=0.0386) were associated with higher odds of developing mydriasis, which was the most common complication.

CONCLUSIONS

MPCP lowered IOP in the short-term but nearly half required additional IOP lowering intervention. Potential complications should be discussed in detail especially when the procedure is being considered for those with good VA and early stage disease.

Outcomes of Micropulse Transscleral Cyclophotocoagulation in Eyes With Good Central Vision

PRECIS

This study is the first to report micropulse transscleral cyclophotocoagulation (MP-TSCPC) use in only good vision patients. MP-TSCPC significantly reduced intraocular pressure (IOP) and glaucoma medication use without any significant reduction in visual acuity at every postoperative follow-up point.

PURPOSE

To evaluate outcomes of MP-TSCPC in eyes with baseline best-corrected visual acuity (BCVA) of ≥20/60.

METHODS

A retrospective review of patients who underwent MP-TSCPC at Mayo Clinic and Ross Eye Institute from July 2016 to August 2017 with BCVA of ≥20/60, and a minimum of 3 months follow-up.

RESULTS

A total of 61 eyes of 46 patients (68.80±17.12 y) underwent MP-TSCPC with a mean follow-up of 10.2±3.1 months. Mean IOP and mean number of glaucoma medications used were significantly reduced from baseline at every follow-up time point (P<0.0001). At month 12, mean IOP was reduced 40.2% from baseline with 85.4% of the patients having an IOP reduction of ≥20%, and mean glaucoma medication use reduced by 0.82±0.53 with 79.6% of the patients having a reduction of ≥1 medication. There was no significant reduction in BCVA from baseline at any follow-up point (P>0.05), except for 10 eyes with a vision loss of ≥2 lines and 5 out of 10 eyes had cataract progression. The probability of complete success (IOP range, 6 to 21 mm Hg or ≥20% IOP reduction; BCVA loss ≤2 lines, no reoperation for glaucoma) was 74.14%, 83.61%, 84.21%, and 75.0% at months 1, 3, 6, 12, respectively. The probability of qualified success (above criteria for IOP, no reoperation and BCVA loss >2 lines) was 81.03%, 91.80%, 94.74%, and 93.75% at months 1, 3, 6, 12, respectively.

CONCLUSIONS

MP-TSCPC should be considered earlier in the management of glaucoma and can possibly be offered as an alternative to incisional glaucoma surgeries.

Niosomal Drug Delivery Systems for Ocular Disease-Recent Advances and Future Prospects

The eye is a complex organ consisting of several protective barriers and particular defense mechanisms. Since this organ is exposed to various infections, genetic disorders, and visual impairments it is essential to provide necessary drugs through the appropriate delivery routes and vehicles. The topical route of administration, as the most commonly used approach, maybe inefficient due to low drug bioavailability. New generation safe, effective, and targeted drug delivery systems based on nanocarriers have the capability to circumvent limitations associated with the complex anatomy of the eye. Nanotechnology, through various nanoparticles like niosomes, liposomes, micelles, dendrimers, and different polymeric vesicles play an active role in ophthalmology and ocular drug delivery systems. Niosomes, which are nano-vesicles composed of non-ionic surfactants, are emerging nanocarriers in drug delivery applications due to their solution/storage stability and cost-effectiveness. Additionally, they are biocompatible, biodegradable, flexible in structure, and suitable for loading both hydrophobic and hydrophilic drugs. These characteristics make niosomes promising nanocarriers in the treatment of ocular diseases. Hereby, we review niosome based drug delivery approaches in ophthalmology starting with different preparation methods of niosomes, drug loading/release mechanisms, characterization techniques of niosome nanocarriers and eventually successful applications in the treatment of ocular disorders.

Assessment of efficacy and safety of micropulse diode laser treatment in glaucoma: One year follow-up

OBJECTIVE

To determine the effectiveness and safety of the micropulse transscleral technique in lowering intraocular pressure in patients with glaucoma.

MATERIALS AND METHODS

A retrospective cohort study was conducted on 143 eyes with various glaucoma subtypes between October 2016 and December 2018. Patients were grouped for analysis based on glaucoma subtypes, preoperative demographics, previous surgical procedures, and postoperative results. The data collected was based on intra- and post-operative complications, intraocular pressure, visual acuity, the need of micropulse re-treatment, incisional glaucoma surgery, and increasing the dose/quantity of medications. A logistic and Cox regression model was performed to determine predictors of therapeutic failure, in addition to building Kaplan-Meier curves.

RESULTS

The mean follow-up was 268 days, and 63% of the patients completed one year. The micropulse procedure achieved a mean intraocular pressure decline of 7.3mmHg (excluding neovascular glaucoma), independent of the glaucoma subtype. The percentage of patients who achieved intraocular pressure less than 20mmHg at 24h was 78%, with 80% at 3 months, 77% at 6 months, and 78% at 12 months. During the follow-up, 29.6% of the patients required additional treatment or a dose increase. Only 2patients presented with minimal postoperative complications.

CONCLUSION

The treatment with transscleral micropulse is a safe and efficient technique for use in glaucoma, attaining a reduction in intraocular pressure and decrease in need of antihypertensive medications within the first year following the procedure.

Minimally Invasive Glaucoma Surgery: What Do We Know? Where Should We Go?

With the arrival of a plethora of new and revolving minimally invasive glaucoma surgery techniques, glaucoma specialists currently are fortunate to have various surgical options that aim to recovery of the function of the aqueous outflow system in different ways. Meanwhile, the aqueous outflow system has become the hot point of researching. In ARVO 2019, a special interest group session was held on new perspectives on minimally invasive glaucoma surgery. Ten surgeons, clinical professors, and experimental scientists were invited to report their latest studies and discussed on five hot topics in this special interest group. This review summarizes the special interest group session and posts the issues of greatest concern, providing insight to the aqueous outflow system and areas that require further study.

Scleral structure and biomechanics

As the eye's main load-bearing connective tissue, the sclera is centrally important to vision. In addition to cooperatively maintaining refractive status with the cornea, the sclera must also provide stable mechanical support to vulnerable internal ocular structures such as the retina and optic nerve head. Moreover, it must achieve this under complex, dynamic loading conditions imposed by eye movements and fluid pressures. Recent years have seen significant advances in our knowledge of scleral biomechanics, its modulation with ageing and disease, and their relationship to the hierarchical structure of the collagen-rich scleral extracellular matrix (ECM) and its resident cells. This review focuses on notable recent structural and biomechanical studies, setting their findings in the context of the wider scleral literature. It reviews recent progress in the development of scattering and bioimaging methods to resolve scleral ECM structure at multiple scales. In vivo and ex vivo experimental methods to characterise scleral biomechanics are explored, along with computational techniques that combine structural and biomechanical data to simulate ocular behaviour and extract tissue material properties. Studies into alterations of scleral structure and biomechanics in myopia and glaucoma are presented, and their results reconciled with associated findings on changes in the ageing eye. Finally, new developments in scleral surgery and emerging minimally invasive therapies are highlighted that could offer new hope in the fight against escalating scleral-related vision disorder worldwide.

Efficacy of travoprost for the treatment of patients with glaucoma

BACKGROUND

This study will evaluate the efficacy of travoprost for patients with glaucoma systematically.

METHODS

A comprehensive literature search will be carried from following literature sources from inception to the present: Cochrane Library, MEDLINE, EMBASE, Web of Science, Google scholar, Chinese Biomedical Literature Database, and China National Knowledge Infrastructure. We will only consider randomized controlled trials on assessing the efficacy and safety of travoprost for glaucoma for inclusion. We will use Cochrane risk of bias tool for the methodological quality assessment for each qualified study. If it is possible, we will pool the outcome data, and will perform meta-analysis.

RESULTS

This study will systematically evaluate the efficacy and safety of travoprost for glaucoma. Primary outcomes include intraocular pressure (IOP), mean IOP, and mean reduction of IOP. Secondary outcomes consist of diastolic ocular perfusion pressure, central corneal thickness, and quality of life, as measured by 36-Item Short Form Health Survey, and treatment-related adverse events included hyperemia, eye pain, and eye pruritus.

CONCLUSION

The findings of the present study will summarize the updated evidence of travoprost for patients with glaucoma.PROSPERO registration number: PROSPERO CRD42019126956.