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At least 631 records · Page 35Linked to original sources
PubMed1992

[Histopathological study on the pars plicata of cynomolgus monkey by the CW Nd:YAG laser].

The pars plicata of cynomolgus monkey eyes were coagulated by a continuous wave (CW) Nd:YAG laser contact system. the intraocular pressure and histopathological changes were observed during the following 3 months. the intraocular pressure decreased during the first week to a minimum level and returned gradually to the pre-coagulation level within 1-3 months. Immediately after photocoagulation, both pigment and non-pigmented epithelium of pars plicata were destroyed. Three weeks after the coagulation nonpigmented epithelium and capillaries showed regeneration. Three months after coagulation, the proliferation of non-pigmented epithelium was conspicuous and regenerating pigment epithelium was observed around the merging of the burned lesion. The CW-Nd:YAG laser contact photocoagulation induced localized destruction of ciliary processes. The regeneration of epithelium and capillaries might indicate that the function of ciliary body could recover to a certain extent and it may be comparatively easy to control the degree of coagulation. These findings suggest that it might be possible to apply CW-Nd:YAG laser photocoagulation to various types of glaucoma.

Animals↗
PubMed1989

Cytochemical studies on pathological Müller cells after argon laser photocoagulation.

The cytochemical localization of G6Pase activity, which is specific to the endoplasmic reticulum (ER) of Müller cells, was studied after argon laser photocoagulation in the guinea pig retina. After argon laser radiation, Müller cells exhibited enlargement of the cytoplasm, an increase of reactive ER and the nuclei, dislocation of the nuclei and diagonal stretching of the cytoplasm. However, cell attachment between Müller cells and the proliferated pigment epithelial cells or Bruch's membrane differed with the degree of retinal coagulation. This histo- and cytochemical method may be useful for examining Müller cells under various pathological conditions.

Animals↗
PubMed1978

[Experience with the new photocoagulator (Zeiss) (author's transl)].

The new Zeiss Xenon-photocoagulator has considerable advantages. The possibility of converging the light beam allows coagulating even prominent areas (folds) in lensless eyes without difficulty. From our experience Xenon coagulation with individually adapted coagulation offers advantages over argon-laser coagulation with relatively short coagulation times.

Humans↗
PubMed1992

Interactions between light and vitreous fluid substitutes.

To determine the interactions between light and vitreous fluid substitutes, we studied the absorption and fluorescence properties of the following fluids that are commonly used in vitreoretinal surgery: Ringer's solution, balanced salt citrate-buffered solution, balanced salt bicarbonate-buffered solution, hydroxypropyl methylcellulose ophthalmic solution, hyaluronate sodium, perfluorocarbons, silicone oil, and fluorosilicone oil. The absorption spectra for all the fluids peaked in the UV-C (reference range <280 nm) and UV-B (reference range from 315 to 280 nm) regions of the spectrum, with little or no absorption in the visible region of the spectrum (from 400 to 700 nm). Emission of almost all of the fluids occurred mainly in the 300- to 360-nm region, with fairly low-quantum efficiency. The limited light absorption properties of the fluids calls for caution during transpupillary and intraocular laser photocoagulation to avoid excessive retinal damage, mainly when the laser power is increased during treatment. Transmission of incoherent light (environmental and ophthalmic artificial light) through highly transparent vitreous fluid substitutes may lead in time to dangerous light exposure, particularly in aphakic eyes. The emitted fluorescence in these fluids generates a minimal risk of long-term damage.

Absorption↗
PubMed1983

Infrared-contact coagulation of parenchymatous organs - report of three cases.

Infrared-contact coagulation of the spleen with an infrared-sapphire-coagulator was applied in two children with subcapsular hematoma and splenic cyst, thereby achieving complete and partial organ preservation, respectively. This method was also used for haemostasis following the dissection of a common liver in Siamese twins. Infrared-contact coagulation is a proper method for organ preservation in injuries or other pathological conditions of parenchymatous organs.

Child↗
PubMed1983

Bjerrum lecture. Treatment of diabetic retinopathy with photocoagulation. Results of photocoagulation therapy of proliferative retinopathy in childhood-onset and maturity-onset diabetes and an approach to the dosage in photocoagulation.

The results of photocoagulation treatment of proliferative retinopathy in childhood onset and maturity onset diabetes are compared with each other. It is clearly shown that childhood onset diabetes needs more photocoagulation treatment than maturity onset diabetes, and that this difference is statistically significant. From this comparison we approach the problem of the dosage of photocoagulation considering either the surface of the coagulated field or the volume of the coagulated retina. Further papers on the same problem will be published from our hospital.

Adolescent↗
PubMed1991

[Treatment of diffuse diabetic maculopathy with "grid pattern argon laser coagulation"].

Sixty eyes of 42 patients with diffuse diabetic macula edema were treated with argon laser in a "grid pattern" mode. The eyes were divided into three groups according to the preoperative visual acuity. In the first group with a preoperative visual acuity of below 0.1 (23 eyes), after 6 months of follow-up, 5 eyes improved in function by at least two lines on a Snellen chart. In the second group with an initial visual acuity of 0.2-0.4 (20 eyes) 5 eyes showed improvement and in the group with a pretreatment visual acuity of 0.5 or more (17 eyes) 6 eyes improved in function. In the first group, the visual acuity did not worsen; in the second group it worsened in 4 eyes. Two eyes in the third group showed a worse visual acuity after treatment. Similar results were found after 1 year of follow-up (27 eyes). After a 2-year follow-up (13 eyes) 9 eyes had a stable visual acuity compared to the preoperative visual acuity. Even though the number of cases with a long follow-up was relatively small, our results show clearly that early application of argon laser coagulation for diffuse macular edema allows stabilization to be achieved and, in some cases, even improvement in the visual acuity.

Adult↗
PubMed1977

[Concentration of ampicillin in the vitreous after photocoagulation of the retina (author's transl)].

After photocoagulation of the retina a higher amount of ampicillin was found in the vitreous of the coagulated eyes, as our tests have shown. The reached concentrations of ampicillin were in the therapeutical region for sensitive germs. The highest concentration of ampicillin was reached when the ampicillin was injected in the edema stage of the coagulation effects. Therapeutical effective concentrations in the vitreous could be kept with this method up to five days after photocoagulation.

Ampicillin↗
PubMed1991

[Changes in the visual field in diabetic retinopathy after grid laser coagulation of the posterior pole of the eye].

The influence of grid laser photocoagulation on the central visual field of 15 eyes with diffuse diabetic maculopathy was studied in a prospective clinical trial. Throughout the 3 month follow-up period, visual fields were monitored by static perimetry using a combination of 30-1 and 30-2 programs of the Humphrey Field Analyzer. Statistical analysis of all clinical parameters shows that visual acuity correlates very well with foveal light difference sensitivity. The overall sensitivity of the 30 degrees field, however, does not correlate significantly with either of them. During the follow-up period, patients' subjective vision improved significantly (p = 0.0234); for the overall sensitivity of the 30 degrees visual field there was a trend towards improvement (p = 0.0692). The sensitivities of the central 10 degrees and 3 degrees of the visual fields, of the fovea and visual acuity did not change. The results of the present study suggest that during the first 3 months after grid photocoagulation of diffuse diabetic macular edema, the treatment affects mainly the retina outside the macula. The improvement in patient vision may be due to these changes in the visual field.

Aged↗
PubMed1997

[Optical coherence tomography of the cornea and the anterior eye segment].

TARGET: The method of optical coherence tomography (OCT) was investigated regarding its suitability and limits for measuring the cornea and the anterior segment of the eye. Furthermore, the stromal expansion of thermally induced lesions in the cornea directly after irradiation was determined within the scope of the laser thermokeratoplasty (LTK). MATERIAL AND METHODS: With the experimental scanning OCT system, x-z sections of the anterior eye segment were made with an optical resolution of about 20 microns axially and 25 microns laterally. Freshly enucleated, tonicized porcine eyes were used as model eyes. Thermal lesions were applied with a continuously emitting laser diode (lambda = 1.86 microns) and various radiation parameters. Before and after coagulation, the cornea was viewed from limbus to limbus in a central OCT scan and the individual coagulation source was measured. RESULTS: Global and local changes of the thickness of the cornea as well as the distance between cornea and lens were measured with high precision. Thermal lesions in their expansion can be dearly presented and matching well with the histologically stained sections, but are not as exactly defined at the edges due to the limited optical resolution, as known from histological preparations. CONCLUSION: With the OCT method quantitative measuring of the anterior eye segment can be performed in vitro and with reduced resolutions also in vivo. Due to the qualitatively good correspondence regarding the dimensions of thermal damage of the cornea with histologically obtained morphometric results, this method can be used for supervision of coagulation directly after LTK as well as for examination of the individual healing process.

Animals↗
PubMed1992

Application of argon beam coagulation in urological surgery.

Argon beam coagulation is a new form of electrocautery that has proved useful to control diffuse bleeding in other surgical specialties. We report its application to urology. Three cases are presented in which argon beam coagulation provided excellent hemostasis in situations that are often difficult to control, such as partial nephrectomy for penetrating trauma, hemorrhagic cystitis refractory to other forms of treatment and after anterior exenteration for bladder cancer. The basis, technique and advantages of argon beam coagulation are discussed, as well as other instances in urological surgery in which it may have application. Argon beam coagulation is an alternative to conventional methods of hemostasis whenever there is a diffusely bleeding operative site.

Adult↗
PubMed1987

Single session treatment for bleeding hemorrhoids.

Fifty consecutive outpatients with bleeding internal hemorrhoids were prospectively treated with a single application of rubber band ligation or infrared coagulation. Complete follow-up observation was obtained in 48 patients (23 underwent rubber band ligation and 25 underwent infrared coagulation). At one month after treatment, 22 patients who underwent rubber band ligation and 16 who underwent infrared coagulation, were symptomatically improved (p less than 0.05). At six months, 15 patients who had undergone rubber band ligation and ten who had infrared coagulation treatment, remained improved (p less than 0.05). There was no statistical difference in the discomfort experienced by either group during or after the procedure as determined by a self-assessment scale. Two patients who underwent rubber band ligation experienced complications--a thrombosed external hemorrhoid developed in one patient and another had delayed rectal bleeding. Although associated with occasional complications after treatment, rubber band ligation is more effective than in infrared coagulation for single session treatment of bleeding internal hemorrhoids.

Ambulatory Surgical Procedures↗
PubMed1997

Histologic study of a shielded macula.

PURPOSE: To illustrate the histologic changes at the macula of an eye shielded from focused light for 76 years. Age-related macular degeneration with a central, subretinal, fibrous scar was present in the fellow eye. METHODS: Autopsy examination of both eyes of a 91-year-old man was performed. The superior half of the macular area of the shielded eye was studied by light microscopy, and the inferior half was studied by electron microscopy. Serial sections through the macular area of the fellow eye were prepared and studied. RESULTS: The shielded eye contained basal laminar deposits up to 6.0 microns in thickness and basal linear deposits up to 1.0 micron in thickness in the macular area. The photoreceptor outer and inner segments of the outer nuclear layer were intact. The macular area of the fellow eye contained a two-component, vascularized, disciform scar that measured up to 250 microns in one area, with retinal pigment epithelial tears at the nasal and temporal margins. Extensive photoreceptor layer atrophy was present. CONCLUSIONS: Such marked asymmetry of macular degeneration in this case may be further evidence of the role of light exposure in the development of age related macular degeneration.

Aged↗
PubMedDate not supplied

[Laser therapy of ocular toxoplasmosis].

The authors present the results of treatment by laser coagulation of inflammatory retino-choroidal foci in 32 persons with ocular toxoplasmosis. The diagnosis of Toxoplasma etiology was set on a basis of positive immunological reaction for Toxoplasma gondii antigen and after exclusion of other etiological factors. Among 42 eyes stabilization of the process after 1 intervention was observed in 34, i.e. in 89 p.c. (period of observation--up to 4 years). In the following 8 eyes arised the necessity to perform additional coagulations because of formation of fresh foci which appeared in 5 eyes after 6 months, in 2 eyes after 1 year and in 1 eye after 2 years since onset. The authors consider the application of laser coagulation in ocular toxoplasmosis as a favourable method together--or independently--with pharmacological treatment.

Adolescent↗
PubMed1988

The retinal effects of copper vapor laser exposure.

The copper vapor laser is a pulsed gas laser which emits energy in two wavelengths simultaneously: 510.6 nm (green) and 578.2 nm (yellow). Each pulse has a duration of 15 nsec, maximal energy of 3 mJ and a peak power of more than 100 kW. It is a variably high repetition rate laser, in the range between 1 kHz and more than 20 kHz. We studied its interaction with the rabbit retina, while using two different repetition rates, 4 kHz and 18 kHz. The histological analysis of the lesion produced by 4 kHz repetition rate showed undesired retinal effects, similar to those caused by other pulsed lasers. On the other hand, the histological examination of the lesion produced by the 18 kHz repetition rate showed a desired coagulation effect, limited to the outer retinal layers, and comparable to a lesion produced by a continuous wave (CW) laser.

Animals↗
PubMed1989

Endoscopic laser applications in the gastrointestinal tract.

The Nd:YAG and, to a lesser degree, the argon laser have become valuable tools for the surgical endoscopist. Over the last 10 years, the impetus for application of these expensive instruments has changed from what the laser can do to what the laser can do better than less expensive technology. Whereas a few controlled randomized studies suggest that the Nd:YAG laser is better than no therapy and equivalent to other heat-producing instruments for control of upper gastrointestinal bleeding, such studies do not exist for other laser applications. Despite the lack of such studies, we remain convinced that, where available, lasers are the instrument of choice for palliation of unresectable mucosal-based cancers, coagulation of arteriovenous malformations, and ablation of certain adenomatous polyps in selected patients. New techniques on the horizon include the use of endoscopic photo-dynamic therapy for treatment of gastrointestinal cancers and endoscopic laser fragmentation of large common bile duct stones. The potential role for a nonthermal "endoscopic scalpel" is questionable because most gastrointestinal tissues are well vascularized; however, a pulsed laser capable of cutting and coagulation, such as the holmium:YAG laser, may be of some value for incisional endoscopic procedures.

Animals↗
PubMed1991

Histopathology of continuous wave neodymium: yttrium aluminum garnet and diode laser contact transscleral lesions in rabbit ciliary body. A comparative study.

Neodymium: yttrium aluminum garnet (Nd:YAG) laser transscleral cyclophotocoagulation has been shown to be an effective method of lowering intraocular pressure (IOP). Transmission and absorption features of diode laser radiation (810 nm) make these new laser sources suitable for production of transscleral thermal lesions. The transscleral effects on rabbit ciliary body of Nd:YAG and diode laser wavelengths were compared using a CW Nd:YAG laser and a CW Aluminum Gallium Arsenide diode laser. Both lasers were delivered by silica optic fibers, 600 microns in diameter. Eight rabbits were treated by applying the optic fiber 0.5 mm from limbus while increasing energy values from 0.2-2 J. The lesions produced at equal energy values underwent gross and histologic and ultrastructural comparison. Gross examination revealed threshold lesions at 1 J energy for the Nd:YAG laser and 0.8 J for the diode laser. The diode laser produced transscleral thermal lesions of the rabbit ciliary body comparable to those achieved by the Nd:YAG laser. The histologic and ultrastructural study showed that diode laser radiation produced more remarkable damage to the ciliary pigmented structures, causing deep coagulation necrosis of the pigmented epithelium, wide disorganization of the collagen in the stroma, and intravascular coagulation phenomena in the ciliary vessels. Before the introduction of these new laser sources in clinical transscleral procedures, further investigation is needed to determine optimal energy levels.

Animals↗
PubMed1994

[Multicenter prospective study of retinopathy of prematurity--IV. Comparison with the data from University of Miami].

We investigated the records of 360 cases of retinopathy of prematurity (ROP) in 12 institutions in Japan (we treated the severe progressive "plus" disease by coagulation therapy), and compared them with data from University of Miami (Ophthalmology 94: 620-629, 1987), as representative of the natural course of ROP without coagulation therapy in those days. The timing of the first examination and the first positive diagnosis were later at University of Miami than in Japan. The time of maximal severity of the disease and occurrence of regression were also later the University of Miami than in Japan. In Japan, the first examination was performed at 29 weeks of postconceptional age or at 3 weeks after birth. At the University of Miami, the first examination was performed at 32 weeks of postconceptional age. If the severe progressive "plus" disease is to be properly treated by photo-coagulation or cryotherapy, it is essential to commence fundus examination earlier.

Florida↗