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Laser treatment of eye disorders in children.

The increasing range of indications for laser treatment and the development of new modalities of lasering have led to a growing tendency to extend this type of treatment to the pediatric population. Problems of compliance in this age group often necessitate the use of general anesthesia. This report describes the operative technique used in 11 children (13 eyes) under the age of 13 years, all of whom underwent laser treatment under general anesthesia for a variety of ocular conditions. Argon or krypton laser photocoagulation was performed in eight children (10 eyes), seven of whom were treated for various retinal pathologies and one for an iris cyst. The other three children underwent Nd:YAG posterior capsulotomy for secondary cataract.

Anesthesia, General↗

The medical case for an Australian national cyclotron facility.

Both a national cyclotron and a reactor are necessary to provide Australia with the complete range of radioisotopes. For the last 17 years, Australia has been well supplied with reactor radioisotopes by the Australian Atomic Energy Commission which provides a daily nationwide distribution service, but, to be self-sufficient, Australia also needs a national cyclotron. Many cyclotron radioisotopes are too short-lived for importation, and the demand can be met only by domestic production. Despite the availability of the necessary expertise and instrumentation, Australian patients are being denied a wide range of important clinical investigations because of the lack of suitable radioisotopes, for example, krypton-81m and iodine-123. An Australian medical cyclotron is overdue. Australia and New Zealand are the only developed countries that do not possess at least one medical cyclotron. The historical events in Australia's quest for a medical cyclotron are summarized, and the medical reasons why the writers believe that Australia should now acquire its own medical cyclotron are reviewed.

Australia↗

[Vascular endothelial growth factor promotes experimental choroidal neovascularization in monkey eyes].

PURPOSE: To evaluate the effect of vascular endothelial growth factor (VEGF) on experimental choroidal neovascularization (CNV) in monkey eyes through clinical, morphometric, and histological observations. METHOD: CNV was induced in both eyes of 6 rhesus monkeys by intense photocoagulation by red krypton laser. Immediately after photocoagulation, 2.5 micrograms of exogenous human VEGF was injected into the vitreous of the left eye in each animal. The right eyes served as controls. The eyes were enucleated 3 days to 12 weeks after photocoagulation and were examined by light and electron microscopy. RESULTS: VEGF-treated eyes developed remarkable serous retinal detachment around the sites of photocoagulation with manifest CNV one week after photocoagulation. Although there was no difference in the incidence of CNV between the treated and control eyes, the treated eyes showed more intense leakage of fluorescein from the CNVs for up to 4 weeks after treatment. Morphometrically, the CNVs were significantly larger and continued to grow longer in the treated than in the control eyes after one week of photocoagulation. Histologically, newly formed vessels with a distinct lumen were present in the treated eyes after 3 days of photocoagulation. CONCLUSION: Intravitreal injection of human VEGF promotes experimental choroidal neovascularization in monkey eyes.

Animals↗

[Clinical application of 133-Xe ventilation scintigraphy].

Xenon-133 ventilation scintigraphy provides three sets of scintigrams: wash-in, equilibrium, and washout images. Krypton-81m or 99mTc-Technegas can be used as alternatives depending on their physical characteristics and the purpose of scintigraphy. Xenon-133 scintigraphy is compatible with SPECT when a multi-detector gamma camera is used. Ventilation images are analyzed by the height/area method to calculate regional lung volume and the mean transit time of the posterior planar view. If perfusion scintigraphy is done during the same examination, a ventilation/perfusion ratio image is also obtained. Factor analysis is applicable to the washout phase and permits a more detailed depiction of uneven ventilation. Series of consecutive SPECT during washout (dynamic SPECT) visualize ventilation in cross section and provide three-dimensional images of regional lung volume and poorly ventilated areas. A major indication for 133Xe scintigraphy is acute pulmonary thromboembolism (PTE) when used in combination with perfusion scintigraphy. The scintigraphic diagnosis of PTE is not inferior to that of contrast-enhanced helical CT, although the latter was initially reported to have higher sensitivity and specificity than scintigraphy. Other important indications are differentiation between primary pulmonary hypertension and chronic pulmonary thromboembolism, and the prediction of postoperative pulmonary function. Ongoing trials are attempting to create functional images of ventilation by CT or MRI, both of which may become rivals of scintigraphy because of their higher image resolution.

Diagnosis, Differential↗

Matrix metalloproteinase (MMP) expression in experimental choroidal neovascularization.

PURPOSE: Matrix metalloproteinases (MMP) are a family of proteolytic enzymes that degrade basement membrane and extracellular matrix proteins. To gain information on the possible role of MMPs in choroidal neovascularization (CNV), we have analyzed the mRNA expression of MMP-2 and MMP-9, two forms of MMPs implicated in ocular neovascularization, in a rat model. METHODS: Choroidal neovascularization was induced in pigmented rats by krypton laser photocoagulation of the fundus whereafter eyes were enucleated at 1, 3, 5, 7, 10 and 60 days. Antisense and sense riboprobes were generated using DNA complementary to MMP-2 and MMP-9, and mRNA expression was analyzed using in situ hybridization. RESULTS: In the untreated eyes MMP-2 mRNA expression was weakly detected in cells within the choroid. In laser-treated eyes MMP-2 mRNA expression was markedly increased and mainly localized to macrophage-like and retinal pigment epithelial (RPE)-like cells invading the choroid, subretinal space and inner retina. This increase in MMP-2 mRNA expression peaked at day 10 whereafter a decline was detected. MMP-9 mRNA expression was low in untreated eyes and did not increase following laser treatment. CONCLUSION: The results show that MMP-2 mRNA expression is increased in experimental CNV, and support of a role for MMP-2 in the development of CNV in age-related macular degeneration.

Animals↗

[YAG laser-induced reperfusion of photothrombotic middle cerebral artery occlusion in rats].

The laser-driven photochemical occlusion of middle cerebral artery(MCA) is much easier, and less traumatic than standard electrocautery or even clip methods, while the infarct size is fairly reproducible. This study aimed to establish the system for YAG laser-induced reperfusion of photothrombotic MCA occlusion. Male spontaneously hypertensive rats(5-7 months old, 350-450 g) were anesthetized with halothane, endotracheally intubated, and mechanically ventilated. The photosensitizing dye rose bengal(20 mg/kg body weight) was administered intravenously over 90 sec starting simultaneously with 3 min of krypton laser irradiation(568 nm, 20 mW). The irradiated middle cerebral artery was completely occluded by an intraluminal thrombus. A YAG laser operating at 355 nm(16 mW, 15 Hz) was focused with a cylindrical lens and positioned with a mirror onto the occluded distal MCA. This YAG laser irradiation for approximately 3 min caused reperfusion of the thrombosed distal MCA. We demonstrated a novel method of reperfusion in the photothrombotic MCA occlusion model. This reperfusion model should facilitate study of the therapeutic window for reversibility in thrombotic stroke.

Animals↗

Laser therapy in the management of choroidal breast tumor metastases.

PURPOSE: To evaluate the potential of laser photocoagulation as a method of treating small metastatic lesions of breast carcinoma in the choroid. METHODS: The 10 eyes of 7 patients were treated by Krypton red or argon green laser applications for small choroidal breast carcinoma metastasis with serous detachment of the retina. Before treatment 5 eyes had visual acuity of finger counting and 5 eyes had visual acuity of 6/15 or better. The treatment was repeated once in all eyes, except 1 eye in which it was repeated 3 times. RESULTS: In all eyes, one to two weeks after the treatment the tumor shrunk, the subretinal serous detachment absorbed, the retina flattened, and the visual acuity improved to 6/6-6/21. No reduction in vision was seen after the second treatment until the end of the follow-up period. In 1 eye, new tumors located elsewhere were again twice successfully treated. Patients reported a significant improvement of their quality of vision, as judged subjectively. CONCLUSIONS: Laser treatment is a feasible, easy, rapid, and effective therapy for small choroidal breast carcinoma.

Adult↗

Suppression of choroidal neovascularization by adeno-associated virus vector expressing angiostatin.

PURPOSE: To test the efficacy of a recombinant adeno-associated virus (rAAV) vector that expresses mouse angiostatin in suppressing experimental choroidal neovascularization (CNV) in a rat model. METHODS: An rAAV vector, rAAV-angiostatin, was constructed to deliver the mouse angiostatin gene. rAAV-angiostatin and a control virus, rAAV-lacZ, were delivered in vivo by subretinal injection in Brown Norway rats, and the delivery was confirmed by reverse-transcriptase polymerase chain reaction (RT-PCR). For a CNV suppression experiment, CNV was generated by fundus krypton laser photocoagulation 7 days after the viral vector injection and was evaluated by fluorescein angiography (FA) and histology. Apoptosis in retina was analyzed using the TUNEL assay. Inflammation in the retina was investigated by immunohistochemistry, using antibodies that recognize lymphocytes. RESULTS: rAAV-angiostatin injection led to sustained expression of the angiostatin gene in chorioretinal tissue for up to150 days. FA analysis revealed significant reduction of the average sizes of CNV lesions in rAAV-angiostatin-injected eyes when compared with rAAV-lacZ-injected eyes at both 14 (P = 0.019) and 150 (P = 0.010) days after injection. Moreover, histologic analysis of CNV lesions also revealed significantly smaller lesions in rAAV-angiostatin-injected eyes (P = 0.004). As for adverse effects, rAAV-angiostatin injection did not cause inflammation or apoptosis of cells in retina and choroid. CONCLUSIONS: This is the first report that subretinal injection of rAAV-angiostatin can significantly reduce the sizes of CNV lesions. This and the absence of apoptosis and inflammation in chorioretinal tissue indicate the feasibility of a gene therapy approach for treatment of CNV disease.

Angiostatins↗

[Choroidal osteoma--diagnosis and ophthalmic management ].

Two cases of the long term observation and clinical findings of choroidal osteoma are presented. Choroidal osteoma (choroidal osseous choristoma) is a very rare, benign, ossifying tumour of the choroid, which typically affects healthy young women. The etiology is unknown. Neovascularisation and haemorrhage is a frequent associated finding. Subretinal neovascularisation, which tend to develop progressive visual loss, may be treated successfully with argon or krypton laser photocoagulation.

Adolescent↗

[Laser photocoagulation of experimentally produced choroidal neovascularization. 2. Comparison of effects by dye and argon blue-green lasers].

Choroidal neovascularization was produced in 18 eyes of 12 rhesus monkeys by application of intense krypton laser photocoagulation. Eight weeks or later, a total of 34 choroidal neovascularizations were treated either by dye laser at wavelengths of 577 or 630 nm or by argon blue-green laser. The treated lesions were evaluated clinically and histopathologically from 24 hours to 3 months after treatment. All the treated lesions were apparently healed by each of the 3 laser modalities. Histopathologically, all the treated choroidal neovascularizations were occluded 24 hours after treatment. At 2 weeks to 3 months after treatment, newly-formed choroidal vessels were present in 3 of 9 lesions (33%) after 577 nm dye laser treatment, in 8 of 9 lesions (89%) after 630 nm dye laser treatment, and in 5 of 8 lesions (62%) after argon blue-green laser. These results seemed to show the clinical superiority of 577 nm dye laser in treating choroidal neovascularization.

Animals↗

[Immunologic disorders in patients with idiopathic subretinal neovascular membrane].

The authors analyze the results of comprehensive clinical and immunologic examinations of 52 patients with this condition (SNVM) in its active and inactive phases, angiographically confirmed, aged 19 to 46; 32 of these were women (61.5%), 20 (38.4%) men. A complex of immunologic methods was employed to reveal the etiology of the condition and the immune status of SNMV patients. The origin of the condition was identified in 44.2% of patients; it was toxoplasmic in 19.2, autoimmune in 15.4, tuberculous in 7.7, and mixed toxoplasmic and tuberculous in 1.9% of cases. T lymphocyte functional activity was inhibited in 37.5% of patients with the exudative hemorrhagic phase of SNMV and in 16.7% of those in the cicatrization phase. Changes in the humoral immunity presenting as gammapathies were detected in 34% of patients, those manifesting by hyperconcentrations of circulating immune complexes in 66.7%, and of cryoglobulins in 37.8% of patients. Krypton laser coagulation was employed in multiple-modality treatment of patients with SNMV. The remissions persisted for 3-5 years.

Adult↗

[Macular involvement in angioid streaks. Gronblad-Strandberg syndrome].

Between 1971 and 1988, we examined 116 eyes of 58 patients with Gronblad-Strandberg syndrome in private practice and in the Retinal Department of the Eye Clinic, Faculty of Medicine, Ankara University. There was initial macular involvement in 79% of cases with angioid streaks. The most frequently encountered lesion, found in 53% of the cases, was choroidal neovascularization. Macular involvement had become bilateral in 80% of the cases after 12.5 months median follow up. Thirteen of the 50 eyes with choroidal neovascularization were treated by argon or red krypton laser photocoagulation. Vision decreased during follow-up in 15% of the 13 eyes treated whereas it decreased in 32% of the 69 eyes unsuitable for laser treatment.

Adult↗

Sonochemical degradation of organophosphorus pesticide in dilute aqueous solutions.

Ultrasonic irradiation was found to accelerate the rate of hydrolysis of omethoate in aqueous solution over the pH range of 2-12. Process parameters studied include pH, steady-state temperature, concentration, and the type of gases. Greater than 96% hydrolysis was observed in 30 minutes through this process and the rate of destruction increased with the help of more soluble and low thermal inert gas. So with Krypton, omethoate was found to undergo rapid destruction as compared with Argon. In the presence of ultrasound, the observed first-order rate of hydrolysis of omethoate is found to be independent of pH. The formation of transient supercritical water (SCW) appears to be an important factor in the acceleration of chemical reactions in the presence of ultrasound. A detailed chemical reaction mechanism for omethoate destruction in water was formulated. Experimental results and theoretical kinetic mechanism demonstrated that the most of the omethoate undergo destruction inside the cavitating holes. A very less effect of temperature on the degradation of omethoate within a temperature range of 20-70 degrees C proves that a small quantity of omethoate undergoes secondary destruction in the bulk liquid.

Hydrogen-Ion Concentration↗

Verteporfin: new indication. In certain age-related macular degeneration: too little evidence.

(1) The standard treatment for neovascular forms of age-related macular degeneration is thermal coagulation by argon or krypton laser, but it is only suitable for patients with juxtafoveal or extrafoveal neovascularisation. (2) Verteporfin, a photosensitising agent, is injected intravenously 15 minutes before non thermal red laser activation. This protocol was initially restricted to patients with predominantly visible neovascularisation in the subfoveal choroidal region. In Europe (but not in the United States), this treatment has now been approved for patients with occult subfoveal neovascularisation, i.e. poorly defined zones of fluorescein diffusion. (3) Use in this indication is supported by a single double-blind trial comparing red laser + verteporfin with red laser + placebo. After one year's treatment there was no difference between the groups in the number of patients whose loss of visual acuity had stabilised. One of the several statistical analyses showed that red laser + verteporfin was significantly more effective than red laser + placebo at two years, after five treatment sessions on average. Only a minority of patients benefited, however, and these cannot yet be identified before treatment. It is unclear whether efficacy persists in the long term. (4) Some patients experienced a transient visual deterioration. Verteporfin infusion can provoke local reactions and thoracic or lumbar pain. Cutaneous photosensitisation can occur for 48 hours after treatment. (5) Treatment with verteporfin is expensive. (6) In practice, there is currently no reason to use red laser + verteporfin in patients with age-related macular degeneration and occult neovascularisation, other than in clinical trials.

Choroidal Neovascularization↗

[A case of isolated absence of the right pulmonary artery].

A 40-year-old woman was admitted to our hospital for investigation of an abnormal chest roentgenogram. She had been well with normal exercise tolerance and had no history of pneumonia. The chest roentgenogram showed decreased vascularity of the right lung, ipsilateral small hemithorax, and shift of the mediastinum toward the right. In the right lung field, hazy and confluent micronodular shadows were seen, and the left lung was emphysematous and hyperlucent. Herniation of the left lung into the contralateral thorax was seen. Although lung perfusion scintigrams showed no detectable blood flow to the right lung, a krypton ventilation study revealed diminished but homogeneous ventilation of the ipsilateral lung. A bronchogram showed normal structure of the bronchi. Cardiac catheterization revealed normal pulmonary arterial pressure. A pulmonary angiogram showed no right pulmonary artery, and absence of other cardiovascular anomalies. Therefore, the diagnosis of isolated absence of the right pulmonary artery was confirmed. An aortic angiogram demonstrated collateral vessels originating from one of the bronchial arteries, the infradiaphragmatic artery, and the right coronary artery. Chest CT disclosed cystic changes in the right lung field.

Adult↗

[Summary of 2004 Chinese National Conference on oral and maxillofacial vascular anomalies].

Congenital vascular anomalies have been the subject of much controversy and confusion over the years, many remain to be investigated and resolved. Authorized by the Managing Director Board of Chinese Stomatological Association (CSA), 2004 Chinese National Conference on Oral and Maxillofacial Vascular Anomalies was successfully held on July 15 to 18, 2004 in Shenzhen Grand Hotel. The conference was sponsored by Chinese Society of Oral and Maxillofacial Surgery (CSOMS), and undertaken by the Second People's Hospital of Shenzhen city. Professor ZHANG Zhen-kang, president of CSA, Professor QIU Wei-liu, president of CSOMS and academician of Chinese Academy of Engineers, and Professor LIU Bao-lin, vice president of CSOMS were present and made important speech at the meeting. More than 120 delegates nationwide attended this conference. Through a 3-day of oral presentation and discussion, the terminology, classification, treatment selection and outcome measurement of oral and maxillofacial hemangioma and vascular malformations were concerted among the delegates. Hemangiomas and vascular malformations have been recognized as distinct diseases that exhibit unique properties and behavior that demand an appropriately tailored treatment plan. The classification of Waner and Suen was adopted and different treatment modalities were reviewed and advocated for different lesions. Delegates were most interested in intralesional injection of Pingyangmycin for venous malformations, Krypton laser photodynamic therapy of venular malformations, Nd:YAG laser therapy for deep head and neck venous malformations after surgical exposure of the lesions, as well as "double" embolization of large venous malformations reported by Professor QIN Zhong-ping. The conference witnessed the foundation of the Division of Vascular Anomalies, Chinese Society of Oral and Maxillofacial Surgery.

Arteriovenous Malformations↗

The excimer lasers.

The excimer lasers are a group of lasers that have found wide application in a variety of medical fields including dermatology, cardiology, ophthalmology, and orthopedics. The word excimer refers to excited dimer. These lasers operate in the ultraviolet range, and examples include the 193 nm argon-fluroide, 248 nm krypton-fluoride, 351 nm xenon-fluoride, and of particular interest to dermatology, the 308 nm xenon-chloride. These lasers utilize a mixture of a noble gas and a halogen as a lasing material. They were first used in medicine for their ability to produce cold tissue ablation, but more recently have been used in dermatology as a method of non-ablative phototherapy.

Adolescent↗

[Clinical study on laser therapy of the venous malformations and hemangioma in oral and maxillofacial regions].

OBJECTIVE: To try to find the best method of laser therapy for the management of venous malformation and hemangioma in oral and maxillofacial regions. METHODS: From June, 1999 to July, 2002, 2 481 cases of venous malformations and hemangiomas were treated by several kinds lasers in our department. The lesions included port-wine stains, venous malformations, telangiectasia and hemangioma. The lasers used were continuous wave CO(2), Nd:YAG and Krypton lasers, pulsed dye laser and ultra-pulsed CO(2) lasers. The treatment modalities were direct irradiation, irradiation after surgical flap raising and photodynamic therapy. RESULTS: Follow up between 2 - 5 years revealed the treatment results as follows: excellent is 79.24%, good is 14.31% and poor is 6.45%. CONCLUSIONS: Laser therapy is one of the best method to treat venous malformations and hemangiomas. The key point is to apply different lasers properly.

Adolescent↗