Acute corneal edema with subsequent thinning and hyperopic shift following selective laser trabeculoplasty

Micropulse Laser Trabeculoplasty with 577 nm Wavelength at 1500 or 1000 mW for Primary Open-Angle Glaucoma: A Pilot Study

Aim: To investigate the efficacy and safety of micropulse laser trabeculoplasty (MLT) using a 577 nm yellow wavelength laser randomly assigned to either 1500 or 1000 mW in patients with primary open-angle glaucoma (POAG). Methods: A prospective, double-blinded study of POAG patients was performed in a single center. MLT treatment included a 577 nm micropulse laser (IRIDEX IQ 577^TM, IRIDEX, Mountain View, CA, USA) to 360° of the trabecular meshwork at randomly assigned varying powers: 1500 mW in one eye (MLT 1500 group) and 1000 mW in the other (MLT 1000 group). Best-corrected visual acuity (BCVA), intraocular pressure (IOP), corneal central thickness (CCT), and endothelial cell count (ECC) were evaluated at baseline (T0), post-operative 1 h (T1), 24 h (T2), 1 month (T3), 3 months (T4), and 6 months (T5) after laser treatment. Topical medications were assessed pre-treatment and at T4. Results: Among the 18 eyes included, we achieved a success rate (IOP reduced > 20%) in 77% of sampled eyes. In particular, IOP reduced at T2 and T3 with both MLT 1500 and 1000 without any significant differences (IOP reduction 22.9% vs. 17.3%, respectively, MLT1500 vs. MLT1000 at T2). The IOP returned to baseline values at T4 and T5 in both groups, with a reduction in topical medications administered from 2.5 ± 1.1 to 2.0 ± 1.2 to the 1500 mW group and from 2.4 ± 1.0 to 1.9 ± 1.0 to the 1000 mW group. At 1 h post-laser treatment, a transient IOP spike was registered among the MLT1500 group. There were no differences in CCT and ECC at any timepoint according to the laser powers. Conclusions: Over a 6-month follow-up period, 577 nm MLT at either 1500 or 1000 mW reduces IOP, enabling a stable reduction in the number of topical medications required for patients treated for POAG without any significant difference in terms of effectiveness and safety.

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.

A Review of Selective Laser Trabeculoplasty: “The Hype Is Real”

Presently, there is no efficacious treatment for glaucomatous optic neuropathy; the current treatment is focused on lowering intraocular pressure (IOP). Studies have demonstrated the safety and efficacy of selective laser trabeculoplasty (SLT) in reducing the IOP in eyes with open-angle (OAG) glaucoma or ocular hypertension (OH). Moreover, the European Glaucoma Society has instated SLT as the first-line or adjunctive treatment in OAG or OH, reiterating its clinical significance. In this review, we outline the old and the new roles of SLT, with an emphasis on clinical practice, and look further into its renewed appeal and future developments.

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.

Hypopyon following selective laser trabeculoplasty

Purpose

To report a hypopyon following selective laser trabeculoplasty (SLT).

Observations

An 85-year-old woman with primary open-angle glaucoma underwent routine SLT. In the early post-procedural period, she presented with pain and decreased vision, and she was found to have hypopyon, trabeculitis, and corneal edema. The patient was treated with prednisolone acetate and empirically with valacyclovir due to the possibility of herpetic keratouveitis. Work-up for potential etiologies was unrevealing. Her symptoms resolved with treatment, and at eight months follow-up her visual acuity and intraocular pressure had stabilized to her baseline.

Conclusions

Though safe, SLT may be associated with rare adverse events requiring intervention. Hypopyon following SLT is extremely rare, and investigation for causes unrelated to the history of SLT should be undertaken as appropriate.

Importance

To the best of our knowledge, this is the first report of a hypopyon following SLT in a patient with no history of inflammatory intra-ocular disease.

The Rationale for Selective Laser Trabeculoplasty in Africa

Glaucoma is the leading cause of irreversible blindness in Africa. The condition is treatable but not curable. There are numerous obstacles to glaucoma care in Africa, including availability, accessibility and affordability of treatments, as well as medication nonadherence among patients. Medical therapy is costly relative to the average income in Africa and it requires daily self-dosing by patients. Surgery is of limited availability in many regions in Africa, and a high proportion of patients refuse surgery because it is expensive. Selective laser trabeculoplasty (SLT) proves to be a favorable alternative to medical or surgical care, as it is highly effective and safe in people of African descent, more cost-effective than medical therapy, quick and easy to perform, and portable. The procedure also requires no postoperative care, thus obviates the issue of nonadherence. In uncontrolled studies, SLT has a high response rate and it lowers intraocular pressure by 30% to 40%, which exceeds the goal in international guidelines for initial therapies. The African Glaucoma Consortium (AGC), a member-driven stakeholder collective, has been formed in part to develop the infrastructure for continent-wide improvements in glaucoma care. It embraces SLT as a potential key tool in their development plans. The mission of AGC includes improving clinical care by educating existing and new health care professionals to expand the provider network, by conducting trials to identify optimal care strategies for glaucoma in Africa, and by facilitating the development of an integrated network of Centers of Excellence to bring SLT and other crucial glaucoma therapies to communities throughout Africa.

Rare corneal complication following selective laser trabeculoplasty

Purpose

This case report describes two glaucoma patients who underwent selective laser trabeculoplasty (SLT) and developed a rare post-procedure corneal complication and subsequent permanent corneal distortions and reduced acuity.

Observations

Both patients experienced early post-procedure corneal edema, reduced visual acuity, and pain. Each patient was treated with topical steroids with resolution of the edema, but each patient had irregular corneal astigmatism which was not present pre-operatively and did not resolve.

Conclusions and importance

There are very few reported cases of post-SLT corneal edema and these typically resolve without long-term complications. The following two cases represent an uncommon adverse event of irregular corneal astigmatism despite resolution of the corneal edema. The exact mechanism of these corneal effects is not known. Practitioners should inform patients of this rare, but possible complication following SLT and consider extra precautions in patients susceptible to corneal edema.

Selective laser trabeculoplasty: past, present, and future

Over the past two decades, selective laser trabeculoplasty (SLT) has increasingly become an established laser treatment used to lower intraocular pressure in open-angle glaucoma and ocular hypertensive patients. In this review we trace the origins of SLT from previous argon laser trabeculoplasty and review the current role it has in clinical practice. We outline future directions of SLT research and introduce emerging technologies that are further developing this intervention in the treatment paradigm of glaucoma.

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

Selective laser trabeculoplasty (SLT) has been used for treatment of primary open-angle glaucoma, ocular hypertension, pigmenter and pseudoexfoliative glaucoma being considered a low-risk procedure. Therefore, transitory and permanent adverse effects have been reported, including corneal changes, subclinical edema, and reduction in endothelial cells and in central corneal thickness. Despite rarer, serious corneal complications after SLT can be permanent and lead to visual impairment, central corneal haze, opacity and narrowing. The mechanism involves increase of vasoactive and chemotactic cytokines causing inflammatory infiltrate, destruction of stromal collagen by fibroblasts and increase of matrix metalloproteinases type 2, which impair reepithelization. SLT also increases free radical production and reduces antioxidant enzymes, resulting in endothelium damages. Low-power laser therapy (LPLT) has been used in regenerative medicine based on its biostimulatory and anti-inflammatory effects. Biostimulation occurs through the interaction of laser photons with cytochrome C oxidase enzyme, which activates intracellular biochemical cascades causing synthesis of a number of molecules related to anti-inflammatory, regenerative effects, pain relief and reduction in edema. It has been showed that LPLT reduces gene expression related to pro-inflammatory cytokines and matrix metalloproteinases, and it increases expression of growth factors related to its proliferative and healing actions. Although radiations emitted by low-power lasers are considered safe and able to induce therapeutic effects, researches based on experimental models for glaucoma could bring important data if LPLT could be an alternative approach to improve acceptation for patients undergoing SLT.

Transscleral Selective Laser Trabeculoplasty Without a Gonioscopy Lens

PURPOSE OF THE STUDY

The purpose of the study was to investigate results of selective laser trabeculoplasty (SLT) performed directly on the sclera without a gonioscopy lens.

DESIGN

Interventional case series, prospective, randomized, masked, controlled clinical trial.

METHODS

Setting: Meir Medical Center, Kfar-Saba, Israel.

STUDY POPULATION

Adults with uncontrolled primary open angle or pseudoexfoliation glaucoma randomized into 2 groups.

INTERVENTION

The controls underwent conventional SLT with 100 spots delivered using a gonioscopy lens for 360 degrees of the trabecular meshwork. The study group underwent irradiation using the same parameters with the laser applications administered on the perilimbal sclera. Study visits: 1 hour, 1, 7, 30, 60, 180, and 365 days postprocedure.

MAIN OUTCOME MEASURES

Intraocular pressure (IOP) and side effects.

RESULTS

Thirty adults were randomized into 2 groups. The mean (±SD) pretreatment IOP was 20.21±3.19 mm Hg for the study group (n=14) and 21.14±2.98 mm Hg for the controls (n=14; P =0.43), dropping to 15.50±3.77 and 15.00±4.08 mm Hg (P =0.74) after 6 months and to 16.00±3.31 and 14.00±2.45 mm Hg (P =0.22) after 12 months. The average IOP reduction after 6 and 12 months was 23.4% and 20.83% for the study group and 27.1% and 33.77% for the controls (P=0.528). Success (a decrease of ≥15% at 6 months with no additional medications, laser, or glaucoma surgery) was achieved in 12 (85.7%) study patients and 9 (69.2%) controls (P=0.385). Complications were mild and transient (n=30), although significantly higher in the controls (n=15; P <0.0001).

CONCLUSIONS

SLT applied directly to the perilimbal sclera may be as efficacious as the conventional procedure for 1 year.

Randomized Prospective Study of the Use of Anti-Inflammatory Drops After Selective Laser Trabeculoplasty

PURPOSE

Evaluating the use of Indomethacin, Dexamethasone, and no anti-inflammatory treatment immediately after selective laser trabeculoplasty (SLT).

MATERIALS AND METHODS

Prospective randomized clinical trial of 132 eyes. Both eyes of the patient underwent SLT. One of the eyes was treated with Indomethacin 0.1% or Dexamethasone 0.1% 3 times daily for 1 week; the other eye did not receive any anti-inflammatory treatment. Intraocular pressure (IOP) and inflammatory parameters were recorded at 1 hour, 1 week, 1, 3, and 6 months.

RESULTS

Cells in the anterior chamber were present in 57% to 71% of the patients after 1 hour. About 16% to 37% of the patients reported pain/discomfort after 1 hour. Redness was present before SLT in 29% to 34% of the patients, probably due to antiglaucoma medication. After 1 hour, the amount of redness recorded raised to 32% to 42%, but the amount of patients with redness returned to pretreatment levels after 1 week. An IOP peak of >5 mm Hg above baseline IOP 1 hour after laser was present in 3% to 9% of the patients. IOP lowered 11% to 21% compared with IOP at baseline. The number of medications needed changed from 1.45 to 1.49 before, to 0.23 to 0.45 six months after SLT.No differential effects based on the kind of anti-inflammatory treatment or no treatment were found for any of the parameters.

CONCLUSIONS

SLT induces little inflammation: anti-inflammatory drops do not make a significant difference in pain, redness, cells in anterior chamber, or peak IOP following SLT.The IOP-lowering effect of the SLT is not influenced by the use of Indomethacin or Dexamethasone.

Acute corneal edema without epithelium compromise. A case report and literature review

El edema de córnea es una entidad que se produce por un gran número de causas y tiene diversas formas de presentación y diferentes grados de afección. En este artículo se reporta el caso de un hombre con edema de córnea agudo sin compromiso epitelial, en el que el cuadro clínico, el examen oftalmológico y los estudios de extensión no lograron establecer su etiología. Además, se hace una revisión de la literatura disponible respecto a todas las posibles causas de edema de córnea agudo, agrupándolas en aquellas que ocasionan el edema por lesión o inflamación epitelial o estromal, por disfunción endotelial o por un aumento en la presión intraocular.

Corneal edema and keratitis following selective laser trabeculoplasty

Purpose

To describe three cases of keratitis following Selective Laser Trabeculoplasty (SLT).

Observations

Three females with a history of glaucoma presented with corneal edema, keratitis (endothelial, epithelial) and decreased visual acuity shortly after SLT. There was variable resolution of symptoms after starting treatment with oral antiherpetics and topical steroids.

Conclusions and importance

With the increase in usage of SLT as a treatment for glaucoma and subsequent reports of keratitis, it is imperative for ophthalmic surgeons to be aware of herpes simplex as a possible risk factor. Prompt treatment with antivirals and steroids can potentially prevent scarring and permanent damage to the cornea.

Corneal topographic alterations after selective laser trabeculoplasty

PURPOSE

To investigate the presence of corneal alterations in the long term among patients with primary open-angle glaucoma (POAG) after a single session of selective laser trabeculoplasty (SLT) treatment.

MATERIALS AND METHODS

The files of the POAG patients who had been treated with SLT were evaluated retrospectively. The Pretreatment Scheimpflug corneal topographic (SCT) findings were then compared with the post-treatment findings.

RESULTS

The files of 33 patients were eligible. The changes in central corneal thickness, thinnest point of cornea, and posterior corneal asphericity at 5 and 8 mm were statistically significant (p = 0.03, 0.01, 0.02, and 0.04 respectively). On the other hand, the simulated K, anterior 3 mm K, anterior 5 mm K, posterior 3 mm K, posterior 5 mm K, anterior asphericity at 3 mm, posterior asphericity at 3 mm, and Zernike values did not change significantly following the treatment (p = 0.19, 0.08, 0.1, 0.3, 0.2, 0.75, 0.09, and 0.3 respectively).

CONCLUSION

SLT can slightly alter pretreatment SCT findings in 3-6 months. Clinicians should wait for at least 6 months after SLT before performing any subsequent surgeries that depend on corneal parameters.

Where does selective laser trabeculoplasty stand now? A review

Background

Chronic treatment of glaucoma can present a challenge in patients who lack the means and/or the discipline to use daily glaucoma medication. We wondered if selective laser trabeculoplasty (SLT) could be a useful alternative.

Methods

Inclusion criteria: controlled trials comparing efficacy of SLT in adult patients with any form of open angle glaucoma or ocular hypertension and case reports on side effects of SLT. Two recent meta-analyses identified eight randomized clinical trials (RCTs) comparing the effect of SLT with medication (prostaglandin analogs) and with argon laser trabeculoplasty (ALT). We took these eight RCTs as reference base and calculated their success rates where they were not given. Other articles were added to elaborate on technique and side effects.

Results

Mean intraocular pressure (IOP) reduction after SLT was 3.8–8.0 mmHg after 6 months to 1 year. Mean success rate of SLT at 6 months to 1 year is 55–82 %. Higher IOP before laser predicts a higher IOP-lowering effect. In terms of mean IOP reduction, reduction in number of medications and treatment success, the effect of SLT was found to show no clinically relevant difference from that of contemporary medication (prostaglandin analogs) and from ALT.

Conclusions

The evidence indicates that SLT is an efficacious primary or adjunctive therapy for treating glaucoma.

Herpetic Stromal Keratitis following Selective Laser Trabeculoplasty

This is a case report describing two cases of disciform corneal edema following uncomplicated selective laser trabeculoplasty (SLT) thought to be secondary to herpes simplex virus (HSV) given the presence of a dendrite, decreased corneal sensation, corneal thinning, and response to therapy with oral and topical antivirals. Corneal edema after SLT treatment has been reported before, but the etiology has been unclear. Our cases highlight HSV as a likely etiology, which may help with prevention and better management of such cases in the future.

Selective Laser Trabeculoplasty: An Update

Selective laser trabeculoplasty (SLT) is an effective treatment option for the reduction of intraocular pressure (IOP) in patients with ocular hypertension or open-angle glaucoma. The mechanism by which SLT lowers IOP is not completely understood and is likely multifactorial. Published studies indicate that SLT is at least as effective as argon laser trabeculoplasty or medications at lowering IOP in many forms of glaucoma. In addition to IOP reduction, SLT may decrease IOP fluctuation and can be successfully used as primary or adjunctive therapy for the management of both early and advanced glaucoma. However, SLT may not be effective in certain forms of glaucoma, and the IOP-lowering effect seems to wane with time. High pretreatment IOP is the strongest predictor of treatment success, even in patients with normal-tension glaucoma. Repeatability of SLT has been controversial, but recent evidence suggests that it can be successfully repeated to achieve additional or recurrent IOP reduction, even in eyes that only had a modest response to initial treatment. Adverse events are uncommon after SLT, and the most common complications such as discomfort and inflammation are typically mild and transient. Further investigation is required to determine the optimal treatment parameters for SLT treatment. Limited evidence suggests that SLT is cost-effective as primary therapy for patients with glaucoma.