Preliminary study on the optical diagnosis of orbital rhabdomyosarcoma by Raman spectroscopy.

To investigate the Raman spectral features of orbital rhabdomyosarcoma (ORMS) tissue and normal orbital tissue in vitro, and to explore the feasibility of Raman spectroscopy for the optical diagnosis of ORMS. 23 specimens of ORMS and 27 specimens of normal orbital tissue were obtained from resection surgery and measured in vitro using Raman spectroscopy coupled to a fiber optic probe. The important spectral differences between the tissue categories were exploited for tissue classification with the multivariate statistical techniques of principal component analysis (PCA) and linear discriminant analysis (LDA). Compared to normal tissue, the Raman peak intensities located at 1450 and 1655 cm-1 were significantly lower for ORMS (p < 0.05), while the peak intensities located at 721, 758, 1002, 1088, 1156, 1206, 1340, 1526 cm-1 were significantly higher (p < 0.05). Raman spectra differences between normal tissue and ORMS could be attributed to the changes in the relative amounts of biochemical components, such as nucleic acids, tryptophan, phenylalanine, carotenoid and lipids. The Raman spectroscopy technique together with PCA-LDA modeling provides a diagnostic accuracy of 90.0%, sensitivity of 91.3%, and specificity of 88.9% for ORMS identification. Significant differences in Raman peak intensities exist between normal orbital tissue and ORMS. This work demonstrated for the first time that the Raman spectroscopy associated with PCA-LDA diagnostic algorithms has promising potential for accurate, rapid and noninvasive optical diagnosis of ORMS at the molecular level.

Sclerectomy with nanojoule energy level per pulse by femtosecond fiber laser in vitro.

The use of nanojoule femtosecond pulses (NFP) for highly precise proceeding in anti-glaucoma surgery was evaluated. According to the observation of scanning electron microscopy (SEM), four types of incision patterns, including subsurface, slit-like, spot and cuboid ablations, were accomplished on in vitro sclera by NFP with little collateral damage. In comparison to microjoule femtosecond pulses (MFP), NFP can make extremely precise incisions with smoother inner surface with less peak power density. The present study first illustrates the potential use of NFP in minimally invasive laser sclerectomy for glaucoma therapy.

Active radiation hardening of Tm-doped silica fiber based on pump bleaching.

Tm-doped fiber laser or amplifier can be applied in varied adverse environments. In this work, we demonstrate the pump bleaching of Tm-doped silica fiber with 793nm pump source under gamma-ray irradiation in the range 50Gy-675Gy. The recovery time, the fiber slope efficiency and the fiber cladding absorption spectra after irradiation and bleaching have been measured. It is found that the recovery time and radiation induce absorption are positively associated with doses, however, the fiber slope efficiency of irradiated TDF and bleached TDF are both negatively correlated with doses. Based on the simulation of the fiber core temperature, the probable mechanism of pump bleaching is also discussed.

External sclerostomy with the femtosecond laser versus a surgical knife in rabbits.

AIM: To experimentally compare the external sclerostomy produced using a femtosecond laser with that made by a surgical knife and to evaluate the healing patterns, efficacy and technical advantages of femtosecond laser sclerostomy. METHODS: In a prospective randomized, controlled, masked-observer study, 10 pigmented rabbits underwent external sclerostomy with a femtosecond laser in the right eye; 10 additional rabbits underwent sclerostomy with a surgical superblade in the right eye. Clinical characteristics, which included bleb morphology and intraocular pressure, were recorded for 1 month after surgery. Six additional rabbits underwent external femtosecond laser sclerostomy in the right eye and mechanical sclerostomy in the left eye and were killed at day 14 after surgery. Histologic staining, immunohistochemistry and scanning electron microscopy were subsequently performed to assess the morphology of the filtering fistula. The titanium-sapphire femtosecond laboratory laser was operating at a repetition rate of 1 kHz, 0.4 mJ pulse energy, a central wavelength of 800nm and a pulse duration of 50 femtoseconds. Mann-Whitney and Kaplan-Meier tests were used for statistical analysis. RESULTS: Successful complete sclerostomy was achieved in each laser-treated eye which was hit only once by the laser. The laser treated time was approximately 15s-16s. In the laser-treated group (n=16), 2 eyes (12%) developed mild hyphema at the site of entry and 8 eyes (50%) showed transient edema in the corneal periphery adjacent to the laser impact zone. The differences between the groups in duration of function blebs and pressure reduction were statistically significant (P=0.025 and 0.016, respectively). The success rate of the laser-treated group was significantly higher than the knife group (P=0.005). Histologically, the subconjunctival connective tissue was loosely arranged with partially patent sclerostomy in the laser-treated eyes at postoperative day 14. This contrasted with the completely scarred sclerostomy tract in the knife group. The mean numbers of fibroblasts and new vessels as well as the amount of new collagen deposition at bleb site were significantly decreased in the laser group (P=0.045, 0.013 and 0.036, respectively). CONCLUSION: The current study demonstrates that external femtosecond laser sclerostomy may offer a safe and effective alternative for the minimally invasive surgical management of glaucoma.

[Preliminary study of femtosecond laser sclerostomy ab externo in a rabbit model of chronic ocular hypertension].

OBJECTIVE: To explore the feasibility, efficacy and safety of performing ab externo sclerostomy with a femtosecond laser in rabbits with chronic ocular hypertension. METHOD: The chronic ocular hypertension model was induced by injecting α-chymotrypsin into posterior chamber. Twenty rabbits with chronic ocular hypertension were randomly divided into experiment and control groups, each group consisting of 10 rabbits. An ab externo sclerostomy using a femtosecond laser was performed in the right eyes in the experiment group. The right eyes in control group were unoperated. The laser was a pulsed titanium-sapphire laser, operating at a repetition rate of 1000 per second, 0.4 mJ pulse energy, a central wavelength of 800 nm and a pulse duration of 50 femtoseconds. The survival of filtration blebs, clinical manifestation and intraocular pressure (IOP) were observed for 1 month after surgery. Animals were killed on days 3, 7, 14 and 30 post-operatively. Hematoxylin and eosin (HE) staining and scanning electron microscopy (SEM) were performed to evaluate the histopathologic changes in filtering tracts. The differences in IOP between the experiment and control groups were analyzed by repeated measures analysis of variance. RESULTS: A 2 mm × 1 mm clear full-thickness scleral incision was created in each eye in the experiment group which was hit only once by the laser. The laser treated time was approximately 15 - 16 s. There was a significant difference (F = 117.46, 39.96, 15.17, 11.62, 15.31, 11.10; P < 0.01). IOP between experiment and control groups at post-operatively day 1, 3, 7, 14, 21, 30. No serious intra- or post-operative complications happened in the treated eyes except for anterior chamber hemorrhage in 2 eyes triggered by laser injury to iris root. A conjunctival bleb was successfully formed in all treated eyes at 1 day after surgery and lasted from 14 to 21 days. Histopathology showed that the perforating scleral incisions created by femtosecond laser were sharply defined, with almost no collateral damage to the surrounding tissue. The tissue repair response in the filtering tracts was characterized by mild hyperplasia of fibroblasts and the loose deposition of a small amount of new collagen fibers. CONCLUSION: The current study demonstrates that ab externo femtosecond laser sclerostomy is a feasible, safe and effective option for the treatment of glaucoma.