[Comparative evaluation of transscleral laser exposure in anatomical experiment]. / Sravnitel'naya otsenka lazernogo transskleral'nogo vozdeistviya v usloviyakh anatomicheskogo eksperimenta.

PURPOSE: This study comparatively analyzed the morphology of eye tissues after laser exposure using the latest generation of transscleral laser techniques - micropulse transscleral cyclophotocoagulation (MP-TSCPC) and laser activation of scleral hydropermeability (LASH) - in an anatomical experiment. MATERIAL AND METHODS: The study used pulsed-periodic radiation of an Er-glass fiber laser (λ=1.56 µm) and radiation of a diode laser (λ=0.81 µm) in the micropulse mode. A comparative morphological evaluation of histological preparations of target scleral and ciliary body (CB) tissues was performed with the study of laser-induced changes occurring after LASH and MP-TSCPC. RESULTS: The study of histological preparations obtained after MP-TSCPC and LASH did not reveal any noticeable signs of an inflammatory reaction or significant destructive changes. There were no signs of pronounced coagulative changes in the form of disorganization of connective and muscle tissue in the exposure area. At the same time, MP-TSCPC was accompanied by thinning and discontinuity of the CB pigment epithelium in the projection of its flat part and expansion of the gaps between the anterior connective tissue fibers fixing the CB to the sclera, which is likely a factor contributing to uveoscleral outflow. After LASH, in the irradiated areas at the level of the outer layers of the sclera (¾ of its thickness) located in the projection of the flat part of the ciliary body, multiple slit-like cavities and enlargements (stretching) of interfiber spaces were revealed with simultaneous compaction of the inner part of the sclera (» of its thickness). CONCLUSION: The identified morphological changes may indicate certain differences in the mechanisms of intraocular pressure (IOP) reduction after MP-TSCPC and LASH. The results of this study suggest that the enhancement of uveoscleral outflow of intraocular fluid and the hypotensive effect after MP-TSCPC may be associated with laser-induced expansion of the interspaces between the anterior connective tissue fibers of the CB in the suprachoroidal space. With LASH, the possible mechanism of lowering IOP may be related rather to an increase in transscleral filtration due to the appearance of slit-like interfiber spaces in the sclera, caused by local contraction of scleral fibers in the area of laser exposure. The absence of pronounced destructive changes at the histological level indicates the gentle nature of both laser techniques and the possibility of expanding the indications for the use of LASH in the treatment of glaucoma, including at its earlier stages.

[Clinical outcomes of laser activation of hydraulic permeability of the sclera in the treatment of advanced glaucoma]. / Klinicheskie rezul'taty lazernoi aktivatsii gidropronitsaemosti sklery v lechenii patsientov s dalekozashedshei stadiei glaukomy.

PURPOSE: This study evaluates the hypotensive effect and the outcomes of intravital morphological changes in the intervention site after laser activation of scleral hydro-permeability (LASH) by pulsed-periodic radiation from an Er-glass fiber laser (λ=1.56 µm) in patients with advanced glaucoma. MATERIAL AND METHODS: LASH surgery was performed in 19 patients (19 eyes) aged 48 to 73 years with uncompensated advanced stage (IIIb-c) glaucoma. In addition to standard methods of investigation, all patients were examined with optical coherence tomography (OCT) and laser confocal microscopy of sclera and conjunctiva (CMSC) at the laser treatment sites, and electronic tonography. RESULTS: The hypotensive effect after LASH in patients with advanced glaucoma was observed in 94.7% (n=18) of cases. The decrease in intraocular pressure (IOP) averaged 24.4% from baseline one month after intervention and 32.96% after six months of follow-up. In 15.7% (n=3) of cases, the recorded IOP decrease was insufficient as its target values were not achieved. However, in the vast majority of patients (n=16), the recorded IOP decrease corresponded to the target values and indicated compensation of the process. Results of complex morphological evaluation after LASH revealed structural changes indirectly indicating possible laser-induced influence on the processes of increased transscleral filtration and uveoscleral outflow. A high positive correlation dependence (r=0.848) was also revealed between the degree of IOP lowering and the increase in the coefficient of ease of aqueous humor outflow, attesting to the fact that IOP lowering was mainly due to the improvement of intraocular fluid outflow. CONCLUSION: The demonstrated efficacy of LASH technology indicates the possibility of its successful application as an independent method of IOP reduction in patients with advanced glaucoma.