SELECTIVE LASER TRABECULOPLASTY 

Guest author

GULAFSHAN FATIMA

Ajmal Khan Tibbiya College 

Aligarh-India

INTRODUCTION 

Selective laser trabeculoplasty (SLT) is an effective treatment option for reduction of intra-ocular pressure (IOP) in patients with ocular hypertension.

SLT is at least as effective as Argon Laser Trabeculoplasty at lowering IOP in many forms of Glaucoma. SLT decreases IOP fluctuation and can be successfully used as a primary or adjunctive therapy for management of both early and advanced Glaucoma. Limited evidence suggests that SLT is cost effective as primary therapy for patients with Glaucoma.

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BASIC PRINCIPLES

SLT is based on the principle of selective laser thermolysis.

According to this concept, radiation energy applied to trabecular meshwork (TM) selectively targets pigmented cells without causing significant collateral thermal damage.

The SLT base is a 532-nm frequency-doubled Q-switched Nd:YAG laser with a fixed spot size of 400-nm and duration of 3 nanoseconds.

The power range for treatment varies from 0.4-1.4 mJ.

These parameters spare surrounding non-pigmented cells as the pulse duration is significantly shorter than thermal relaxation time (1 microsecond) of melanin granules contained in pigmented TM cells.

MECHANISM OF ACTION

The exact mechanism by which IOP is lowered by SLT is unknown and probably multifactorial.

SLT appears to lower IOP by increasing trabecular outflow.

Proposed mechanism of action include: structural alteration inflammatory response with remodeling of extracellular matrix and stimulation of TM cell proliferative changes.

SLT IN SPECIFIC TYPES OF GLAUCOMA

SLT is useful in various types of glaucoma including:

Normal tension glaucoma

Pseudoexfoliative glaucoma

Pigmentary glaucoma

Steroid induced glaucoma

Normal tension glaucoma:

SLT can have a significant IOP lowering effect in patients with NTG, albiet with a smaller absolute reduction in IOP. The use of SLT in NTG has been limited historically because of the fact that the most reliable predictor of success is a higher preoperative IOP. Lee et. al. treated 45 NTG eyes with 360-degree SLT after 1 month of medication washout, the IOP was significantly reduced.

Steroid induced glaucoma:

Although there is limited data available, SLT appears to effectively lower IOP in patients with steroid induced glaucoma and may even help prevent IOP spikes from subsequent steroid treatment.

SLT was found to produce a 35.9% drop in IOP over 12 months of follow up in patients with steroid induced glaucoma.

CONCLUSIONS

SLT is an effective treatment option for the reduction of IOP in patients with ocular hypertension and open angle glaucoma. Based on published data SLT is at least as effective as ALT and medications.

There is evidence that SLT can successfully be repeated to achieve additional or recurrent IOP reduction in eyes that had a modest response to initial treatment.

Adverse effects are uncommon after SLT. The most common complications being mild and transient rise in IOP immediately following the procedure.

SLT can be a useful and effective treatment option when medications are ineffective or are causing unwarranted side-effects.