In vitro ear cartilage shaping with carbon dioxide laser: an experimental study.

Deformed cartilage remodeling appears to be a challenge, as cartilage tends to keep its initial shape because of internal stresses. Cartilage can be remodeled with heat, and this report describes the use of a CO2 laser beam for in vitro cartilaginous tissue remodeling. Straight cartilage samples were removed from the ears of 21 rabbits deprived of perichondrium and remodeled with the CO2 laser at an output power of 3 W, a spot diameter of 2 mm, and an exposure time of 0.5 second. The remodeled cartilages and control samples were implanted into the rabbits' backs and retrieved 6 to 12 months later. Histologic and morphological analysis showed that the irradiated cartilages retained both their shape and their viability. This may be a useful clinical technique for in situ remodeling of a deformed cartilage in operations such as septoplasty.

Ciliary body PDT in pigmented rabbit eyes: effect of single and repeated treatment.

PURPOSE: To investigate the morphologic and hypotensive effect of contact transscleral ciliary body PDT in pigmented rabbit eyes. METHODS: The right eyes of 33 pigmented rabbits were irradiated using chloraluminum sulfonated phthalocyanine as photosensitizer and a diode laser (670 nm) as the light source. Twenty-five animals received a single treatment. Eight animals received a second treatment 13 days after the first one. Photosensitizer was administered by means of continuous intravenous infusion. Ciliary body was irradiated transsclerally by means of an optic fiber applied on the corneoscleral limbus. In all cases 14-16 laser applications were performed to cover 360 degrees of the ciliary body. Animals were followed for a maximum of 30 days by means of tonometry and biomicroscopy. Retreatments were performed using the same irradiation protocol. At the end of the follow up time animals were sacrificed and their were eyes prepared for light and electron microscopy. RESULTS: Transscleral ciliary body PDT resulted in significant but temporary reduction of IOP in all cases. The effect lasted about two weeks. Retreatment led to a new significant drop of the IOP, which lasted about two weeks again. In histological examination the initial effect was vascular thrombosis, followed by edema and disintegration of the ciliary epithelial layers. In all cases the appearance of the ciliary body had returned to normal 15 days after irradiation. CONCLUSION: Contact transscleral PDT with the treatment parameters used in this study results in significant but temporary functional and morphological alteration in pigmented rabbits ciliary body.

Topical use of zinc desferrioxamine for corneal alkali injury in a rabbit model.

PURPOSE: To evaluate the efficacy of topical zinc desferrioxamine in acute corneal alkali injury in rabbits. METHODS: Twenty rabbits were anesthetized and a standardized alkali burn (1N NaOH) was performed in the center of the cornea (7.5-mm diameter). The animals were randomly divided into two groups and treated (double-masked) with topical zinc desferrioxamine, 220 microM, (group 1) or its vehicle (group 2). Drops were applied 7 times/day for 28 days. Topical gentamicin, 0.3%, was instilled twice a day. Animals were evaluated twice a week. At each examination (using the slit-lamp), the depth of corneal ulcer was graded as follows: 0, no ulcer; 1, tissue loss less than one third of corneal thickness; 2, one third to two thirds tissue loss; 3, more than two thirds tissue loss; 4, descemetocele; or 5, perforation. Ulceration area, vascularization, and epithelial defects also were measured. RESULTS: During the study period, the grading of mean corneal ulcerations in group 1 ranged from 0.2 to 1.00, whereas in group 2, it ranged from 1.4 to 2.7. The mean grade and area of ulceration in group 2 were greater than those in group 1 (p < 0.05). CONCLUSION: Topical zinc desferrioxamine may be an adjunctive treatment in protecting the cornea against induced alkali injury.

Transscleral ciliary body photodynamic therapy using phthalocyanine and a diode laser: functional and morphologic implications in albino rabbits.

BACKGROUND AND OBJECTIVES: To evaluate the morphologic and functional effects of ciliary body photodynamic therapy (PDT) using phthalocyanine and a diode laser. MATERIALS AND METHODS: The upper half of the left eye ciliary body of 16 albino rabbits was irradiated transsclerally using a 670-nm diode laser (400 mW/cm2) after intravenous injection of phthalocyanine (6 mg/kg). The animals were observed for a maximum of 2 months by means of tonometry, biomicroscopy, and fundus examination. At the end of the follow-up period, they were killed and their eyes were prepared for light and electron microscopy. RESULTS: Transscleral PDT resulted in intraocular pressure (IOP) reduction in the treated eye, which lasted about 2 weeks. During this time, the treated eye had IOP values that were significantly lower than its baseline IOP values and the IOP values of the untreated eye (P < .05). One month after the procedure, the IOP had returned to baseline values. Histologic examination revealed vascular endothelial cell damage causing vascular thrombosis in the treated areas. The architecture of the two ciliary epithelium layers showed a significant abnormality. Disappearance of epithelial apical junction complexes and loss of the normal b-cytomembrane enfolding were observed in the course of electron microscopic examination. Large intercellular spaces between epithelial cells were noticed. All of these changes had subsided by the end of the second postoperative month. CONCLUSION: Transscleral phthalocyanine-mediated PDT with the parameters used in this experiment results in significant but temporary functional and morphologic alterations in the ciliary bodies of albino rabbits.

Histological evaluation of phthalocyanine mediated photodynamic occlusion of corneal neovascularization enhanced by hyperbaric oxygenation.

PURPOSE: We evaluated the effective irradiation parameters for photodynamic thrombosis of experimental corneal neovascularization enhanced by simultaneous hyperbaric oxygenation. METHODS: Neovascularization was provoked in both eyes of each of 35 albino rabbit corneas using the intracorneal suture technique. The lasered animals were divided in 3 groups. Group 1 (10 rabbits) was treated under hyperbaric conditions (28 atm for 25 min.); group 2 (5 rabbits) was treated breathing pure oxygen delivered by a face mask; group 3 (10 rabbits) was treated breathing room air. The fourth group (10 rabbits) was used for control. Animals were anaesthetized, and irradiation of new corneal vessels was carried out 30 minutes after the injection of 5 mg/kg chloroaluminum sulfonated phthalocyanine. A 670 nm diode laser with a power 4 mW and a spot diameter 350 mm was used. Exposure times necessary for vascular occlusion were registered. Histological examination was carried out at the end of the follow-up time. RESULTS: Exposure times were significantly lower in groups 1 and 2 as compared to group 3 (1.75 +/- 0.15 min., 3.1 +/- 0.4 min., and 4.75 +/- 0.15 min. respectively). Total light dose averaged 490 J/cm,2 870 J/cm,2 and 1330 J/cm,2 respectively. Histological examination revealed thrombus formation in the targeted vessels of all three investigated groups. CONCLUSION: Combination of PDT with hyperbaric oxygenation results in an acceleration of the photodynamic process and provides for a possibility of significant reduction of photodynamic dose.

Photothrombosis of retinal and choroidal vessels in rabbit eyes using chloroaluminum sulfonated phthalocyanine and a diode laser.

BACKGROUND AND OBJECTIVES: Photothrombosis is a relatively new photodynamic application leading to vascular occlusion. In the current work the effectiveness of phthalocyanine and a diode laser in photothrombosis of normal retinal and choroidal vessels was evaluated. STUDY DESIGN, MATERIALS AND METHODS: Big retinal vessels of temporal myelin wing were irradiated using a 670 nm diode laser (2 mW, 0.5 mm2) after the injection of chloroaluminum sulfonated phthalocyanine (5 mg/kg) in twenty albino rabbits. Animals were followed up to a maximum of 7 months using fundus photography, fluoroangiography, and histology. RESULTS: Photothrombosis of the irradiated retinal vessels and of underlying choroidal vessels resulted in all treated eyes after 13 to 17.5 min of irradiation. The retinal vessels were patent again by the 7th day after the procedure. Choroidal vessels remained closed during the whole follow-up period. Light and electron microscopy demonstrated occupation of irradiated choroidal and retinal vessels by platelet thrombi. Damage of endothelial cell structure of these vessels could be seen. Outer retinal and RPE damage localized at irradiation area was observed. CONCLUSION: The combination of phthalocyanine with a low power diode laser is a simple and effective way for the induction of photodynamic thrombosis in fundus vessels.

Phthalocyanine mediated photodynamic thrombosis of experimental corneal neovascularization: effect of phthalocyanine dose and irradiation onset time on vascular occlusion rate.

The aim of this study was to evaluate the possible influence of phthalocyanine dose and of time interval between phthalocyanine injection and irradiation commencement on the rate of experimental corneal neovascularization photodynamic thrombosis in albino rabbits. New corneal vessels were irradiated with a diode laser (670 nm, 2 mW) after the intravenous injection of chloroaluminum sulfonated phthalocyanine. Different animals were irradiated either 5 min after the injection of different phthalocyanine doses (3, 6, 8, 12, or 14 mg/kg), or at different times (5 min, 24 h, or 58 h) after a standard phthalocyanine dose (3 mg/kg) injection. Irradiation time necessary for vascular occlusion was recorded. Decrease of phthalocyanine dose as well as delay of irradiation onset resulted in a statistically significant increase of irradiation time. Electron and light histological examination revealed platelet thrombi inside irradiated corneal new vessels. Damage in the vascular endothelial cell membrane and in intercellular contact structure was noted, leading to disorganization of the endothelial cells layer and death of most endothelial cells. These results indicate that both early commencement of irradiation after phthalocyanine injection and phthalocyanine dose increase accelerate the rate of phthalocyanine mediated corneal neovascularization photodynamic thrombosis. Thrombosis seems to result from photochemically induced vascular endothelial cell damage.

Effectiveness of corneal neovascularization photothrombosis using phthalocyanine and a diode laser (675 nm).

We used chloroaluminum sulfonated phthalocyanine as a photo-sensitizer and a diode laser as a light source for induction of photothrombosis of corneal neovascularization. Corneal neovascularization was induced in 1 eye of each of 10 New Zealand white rabbits using intrastromal 6.0 silk sutures. After the intravenous injection of phthalocyanine in a dose of 4 mg per kg of body weight, photothrombosis was carried out using a diode laser emitting at 675 nm. The animals were followed up by both fluorescein angiography and slit-lamp photography for up to three months. At the end of the follow-up period the eyes were prepared for histology. After photothrombosis, thrombus formation was induced within new vessels demonstrating histological characteristics of both arterioles and venules. Most of the vessels disappeared or remained closed during the follow-up period. Recanalization of some of the thrombosed vessels occurred within the first 20 days after the operation. The combination of phthalocyanine and a 675 nm diode laser is effective for the induction of photothrombosis of corneal neovascularization.