Could adverse effects and complications of selective laser trabeculoplasty be decreased by low-power laser therapy?

Selective laser trabeculoplasty is safe and effective in patients previously treated with prostaglandin analogs: An evidence-based review

PURPOSE

Prostaglandin analogs (PGAs) are first-line treatments for ocular hypertension (OHT) and open-angle glaucoma (OAG). However, frequent side effects and high costs hinder patient's compliance resulting in disease progression. Evidence suggests selective laser trabeculoplasty (SLT) may be considered a first-line treatment for OHT and OAG due to its safety profile, minor side effects, and reduced costs. Considering that PGAs and SLT share action mechanisms, it is hypothesized that previous PGA therapy may affect subsequent SLT efficacy. Therefore, we analyzed if PGAs reduce SLT efficacy.

METHODS

An evidence-based review was performed to assess the safety and efficacy of SLT in patients previously treated with PGAs. For this purpose, we performed an extensive literature search using the National Library of Medicine's PubMed and Google Scholar database for all English language articles published until May 2021.

RESULTS

There is evidence of non-superiority of PGAs therapy versus SLT for OHT and OAG. A multicenter, randomized, observer-masked clinical trial (RCT) of untreated OHT and OAG patients concluded that SLT should be offered as the first-line treatment for these patients. This study was supported by a meta-analysis of RCTs, comparing SLT efficacy versus antiglaucoma drugs only, with the advantage of an SLT lower rate of adverse effects.

CONCLUSIONS

Cost-effectiveness, patient compliance, and antiglaucoma drugs' side effects, including higher surgical failure, favor consideration of SLT as first-line therapy for OAG and OHT. Furthermore, SLT efficacy does not seem to be affected by prior PGA administration; however, larger cohort, comparative, multicenter RCTs are necessary to answer this question.

Effectiveness of selective laser trabeculoplasty and its safety on corneal endothelium in patients with primary open angle glaucoma and ocular hypertension

BACKGROUND AND AIM

The aim of this study was to evaluate the effectiveness of selective laser trabeculoplasty (SLT) in patients with primary open-angle glaucoma (POAG) and ocular hypertension (OHT), and to assess its effects and safety on corneal endothelial cell morphology.

PATIENTS AND METHODS

Forty patients with POAG (15 cases, 23 eyes) and OHT (25 cases, 48 eyes) were prospectively evaluated. All cases underwent pachymetry, goniolens examination, Humphrey Visual Field Test, Optical Coherence Tomography, and Corneal Confocal Microscopy measurements. Patients whose intraocular pressure (IOP) was more than 21 mmHg in POAG and OHT, underwent SLT. SLT treatment was applied to the inferior 180° region of the trabecular meshwork. Central corneal thickness (CCT), IOP, and specular microscopy examinations were taken at the visits before and after the first day, first week, first month, third and sixth months of the SLT procedure. Retinal nerve fiber layer (RNFL) thickness measurements and visual field tests were performed before and six month post-SLT. Results of the pre-SLT and post-SLT measurements were compared and a P value of lower than 0.05 was considered statistically significant.

RESULTS

The results of IOP measurements at first week, first month, third, and sixth month post-SLT were significantly lower than the results before and post-SLT first day. No significant difference was found between the results of initial and final measurements of CCT and specular microscopic corneal endothelial cell morphology evaluation. There was no statistically significant difference between the results of initial and final measurements for RNFL thickness and the results of the visual field tests.

CONCLUSION

SLT is an effective treatment modality for reducing IOP in patients with POAG and OHT and is also a safe procedure in terms of the entirety of corneal endothelial cell morphology.

Low-energy Selective Laser Trabeculoplasty Repeated Annually: Rationale for the COAST Trial

The recent Laser in Glaucoma and Ocular Hypertension Trial provided the evidentiary basis for a paradigm shift away from the historical medication-first approach to glaucoma--which has numerous limitations, the most important of which is poor adherence to therapy --and toward a laser-first approach. Now 20 years after its commercialization, selective laser trabeculoplasty (SLT) is routinely performed consistently with its initial description, with energy titrated to the appearance of fine, champagne-like cavitation bubbles. A recent data set suggested that lower energy SLT, applied as primary therapy and repeated annually irrespective of intraocular pressure--rather than pro re nata when its effect wanes and irrespective of intraocular pressure rises --yields longer medication-free survival than standard energy SLT repeated pro re nata. A new study--Clarifying the Optimal Application of SLT Therapy --has been initiated to explore this preliminary finding in a pair of consecutive randomized trials. Herein, we provide an evidence-based rationale for the use of low-energy SLT repeated annually as primary therapy for mild to moderate primary open-angle glaucoma or high-risk ocular hypertension.

Partial corneal recovery following selective trabeculoplasty-induced keratopathy: Longitudinal analysis through scheimpflug imaging

Purpose

To report an uncommon case of hyperopic shift and corneal haze, flattening and thinning following a single session of selective laser trabeculoplasty (SLT), and provide longitudinal clinical data and serial analyses of corneal profile through Scheimpflug imaging. Furthermore, a careful literature review was undertaken to determine possible risk factors for this complication.

Observations

A 47-year-old woman presented with blurred vision and mild corneal edema and haze three days following routine SLT. Ten days later, corneal edema resolved, but she was still symptomatic. Refraction exam revealed a significant hyperopic shift and high astigmatism (+4.00–6.00 x 80° versus −11.50 -0.75 x 170° at baseline). Scheimpflug imaging revealed a partial collapse of the corneal architecture, with an expressive central cornea flattening (>10 diopters) and thinning (>190μm). Over six months, refractometric and corneal parameters gradually (but not completely) returned to their pre-operative values.

Conclusions and Importance

This tetrad of clinical findings - hyperopic shift, corneal haze, flattening and thinning - following SLT is referred herein by the authors as selective trabeculoplasty-induced keratopathy (STIK), which is a rare but serious complication. A critical analysis based on this case findings and on the few others reported so far suggests high-myopic patients to be more predisposed to this complication, as all reported cases had −5.0 diopters or more. Future studies are warranted to determine whether this complication can be prevented.

Quantum biology in low level light therapy: death of a dogma

Background

It is shown that despite exponential increase in the number of clinically exciting results in low level light therapy (LLLT), scientific progress in the field is retarded by a wrong fundamental model employed to explain the photon-cell interaction as well as by an inadequate terminology. This is reflected by a methodological stagnation in LLLT, persisting since 1985. The choice of the topics is, by necessity, somewhat arbitrary. Obviously, we are writing more about the fields we know more about. In some cases, there are obvious objective reasons for the choice. Progress in LLLT is currently realized by a trial and error process, as opposed to a systematic approach based on a valid photon-cell interaction model.

Methods

The strategy to overcome the current problem consists in a comprehensive analysis of the theoretical foundation of LLLT, and if necessary, by introducing new interaction models and checking their validity on the basis of the two pillars of scientific advance (I) agreement with experiment and (II) predictive capability. The list of references used in this work, does contain a representative part of what has been done in the photon-cell interaction theory in recent years, considered as ascertained by the scientific community.

Results

Despite the immense literature on the involvement of cytochrome c oxidase (COX) in LLLT, the assumption that COX is the main mitochondrial photoacceptor for R-NIR photons no longer can be counted as part of the theoretical framework proper, at least not after we have addressed the misleading points in the literature. Here, we report the discovery of a coupled system in mitochondria whose working principle corresponds to that of field-effect transistor (FET). The functional interplay of cytochrome c (emitter) and COX (drain) with a nanoscopic interfacial water layer (gate) between the two enzymes forms a biological FET in which the gate is controlled by R-NIR photons. By reducing the viscosity of the nanoscopic interfacial water layers within and around the mitochondrial rotary motor in oxidatively stressed cells R-NIR light promotes the synthesis of extra adenosine triphosphate (ATP).

Conclusions

Based on the results of our own work and a review of the published literature, we present the effect of R-NIR photons on nanoscopic interfacial water layers in mitochondria and cells as a novel understanding of the biomedical effects R-NIR light. The novel paradigm is in radical contrast to the theory that COX is the main absorber for R-NIR photons and responsible for the increase in ATP synthesis, a dogma propagated for more than 20 years.