Interventional radiology with laser in bone and joint

Laser energy is able to ablate, coagulate, and vaporize tissues. Its transmissibility in thin optical fibers makes it an ideal tool for use in percutaneous procedures. This article describes two applications in interventional musculoskeletal radiology. In percutaneous laser disc decompression the laser source is used to vaporize a small portion of the nucleus pulposus. In interstitial laser photocoagulation of osteoid osteoma the laser energy is used to coagulate and destroy the tumor by direct heating.     

Expression of cell adhesion molecules and vascular endothelial growth factor in experimental choroidal neovascularisation in the rat

AIMS: To investigate the longevity and reproducibility of choroidal neovascularisation (CNV) induced by krypton laser photocoagulation in the rat. The presence of cell adhesion molecules (CAMs) and vascular endothelial growth factor (VEGF) during the development of CNV was also studied. METHODS: 67 pigmented rats underwent retinal photocoagulation by krypton laser. The eyes were examined by either single or serial fluorescein angiography at 3 days, 1, 2-3, 4-5, 7-8, and 12 weeks post photocoagulation. The expression of CAMs (ICAM-1, E-selectin, and CD44) and VEGF post photocoagulation was studied by immunohistochemistry. RESULTS: CNV related fluorescein leakage appeared in 46.4% of 766 laser spots delivered to the 58 eyes that were tested at 2-3 weeks post treatment. The ratio of hyperfluorescent laser sites did not change significantly at 8 weeks post laser. The number of leaky spots was independent of the total number of lesions delivered to each eye (at 2-3 weeks post laser 10-15 spots/eye: 44% and 25-30 spots/eye: 49%; t = 0.7673; p = 0.3903). Nine eyes were followed by serial angiography between 2 and 12 weeks. The laser spots with fluorescein leakage at 2 weeks (51.5%) remained leaky at 12 weeks (51.5%). Histopathologically, macrophage accumulation peaked at 5 days and CNV was firstly observed at 1 week post photocoagulation. ICAM-1, E-selectin, CD44, and VEGF were maximally induced at 3-5 days post laser photocoagulation, and were localised to RPE, choroidal vascular endothelial, and inflammatory cells. VEGF was also detected in intravascular leucocytes at the sites of laser lesions. CONCLUSIONS: These studies demonstrated that krypton laser photocoagulation can be successfully used to produce lesions similar to those of human CNV. The response induced remained present for an extended period of time (12 weeks), thus offering a potential model to screen candidate CNV inhibitory agents. In addition, it is proposed that the expression of ICAM-1, E-selectin, CD44, and VEGF before new vessel formation might be linked to the initiation of CNV.     

Treatment of retinoblastoma with the transscleral diode laser

PURPOSE: To report a case of retinoblastoma successfully treated by contact transscleral photocoagulation with a diode laser. METHODS: In an 18-month-old girl, a small (6.6 x 4.3 x 3.2-mm) discrete retinoblastoma anterior to the superotemporal arcade in the right eye was treated with transscleral photocoagulation using a diode laser (810 nm) and a fiberoptic probe. RESULTS: The tumor regressed after photocoagulation, leaving a pigmented chorioretinal scar. There was no regrowth of the tumor 12 months after photocoagulation. CONCLUSION: Contact transscleral photocoagulation with a diode laser may be a viable new treatment for small retinoblastoma.     

The study on changes of macular light sensitivity before and after photocoagulation for diabetic macular edema

OBJECTIVE: The study was designed to determine whether laser photocoagulation could damage macular visual function in treatment of diabetic macular edema. METHODS: A prospective clinical trial was taken to determine the effects of argon green (514.5nm) laser photocoagulation on macular light sensitivity (MLS) by comparing the self MLS pairing data collected from a Humphrey automatic visual field analyzer before and after the procedure. Nineteen eyes of 15 patients with diabetic macular edema consistent with its diagnostic criteria were enrolled in this study, a follow-up period being 3 months. RESULTS: The mean MLS at the photocoagulation area, non-photocoagulation area, 5 degrees and 13 degrees eccentricity were significantly decreased within 1 week after the treatment, the drops of MLS were 1.85 dB, 1.05 dB, 0.99 dB, 1.66 dB respectively (P < 0.05). The mean reduction of MLS at the fovea within 1 week after the treatment has no statistical significance. The MLS gradually recovered at the 1st and 3rd month after photocoagulation, and the visual acuities in most of the cases were stable or increased. CONCLUSIONS: MLS is affected little by laser photocoagulation, and photocoagulation can reduce the risk of visual loss or increase visual acuity in an eye with diabetic macular edema.     

Photocoagulation of well-defined choroidal neovascularization in age-related macular degeneration: clinicopathologic correlation

PURPOSE: To present the clinicopathologic features of the eyes of a patient with age-related macular degeneration (ARMD): the right eye was treated for well-defined extrafoveal choroidal neovascularization (CNV), and the left eye had an untreated disciform scar. METHODS: The patient was studied ophthalmoscopically and by fluorescein angiography at the time of presentation and on follow-up examinations up to 54 days after laser treatment, when he died. The posterior portions of both eyes (obtained postmortem), including the macula and optic nerve head, were sectioned serially for light microscopy. Tissue sections from both eyes were removed from glass slides and studied by transmission electron microscopy. RESULTS: Histopathologic study of the right eye disclosed a thin layer of basal laminar deposit throughout the posterior pole. Two defects in Bruch's membrane without CNV were present within the area of laser photocoagulation located superior to the fovea. No CNV was present in the scar. Eleven areas of early CNV were present in the posterior pole. Histopathologic study of the left eye showed a prominent basal laminar deposit throughout the posterior pole. A 2.6 x 2.7 mm disciform scar was present that was located mostly in the subretinal space. Four sources of CNV were present. CONCLUSIONS: The clinicopathologic features of a treated eye with well-defined extrafoveal CNV, and the fellow eye with a disciform scar, both associated with ARMD, are presented. Although laser treatment obliterated a choroidal neovascular membrane, 11 additional areas of early, subclinical CNV were present.     

Association between watershed zone and visual field defect in normal tension glaucoma

In order to evaluate the association between the watershed zone and glaucomatous optic damage, we performed indocyanine green fluorescence angiography with a scanning laser ophthalmoscope in 54 eyes of 27 patients with normal tension glaucoma. The visual field indices were measured with a Humphrey Field Analyzer. We identified 8 eyes (14.8%) of 7 patients with a watershed zone not including the optic nerve head (type I), 32 eyes (59.3%) of 20 patients with the zone partially including the optic nerve head (type II), and 14 eyes (26.0%) of 10 patients with the zone including the optic nerve head (type III). Of the total of 27 patients, 10 patients (37.0%) had different types in each eye. In these patients, the mean deviation (MD) of visual field indices was worse in the eye with the watershed zone which included a larger part of the optic disc than in the contralateral eye (p < 0.05). Conversely, the eye with worse MD than the contralateral eye had a watershed zone which included a larger part of the optic disc than the other eye (p < 0.05). The location of watershed zone appeared to influence the progression of the visual field defect.     

The function of sensory nerve fibers in lumbar radiculopathy. Use of quantitative sensory testing in the exploration of different populations of nerve fibers and dermatomes

STUDY DESIGN: The function of sensory nerve fibers in patients with lumbar radiculopathy and in control individuals was evaluated using quantitative sensory testing. OBJECTIVES: To investigate the effect of lumbar nerve root compression on different populations of nerve fibers and to explore the function of sensory nerve fibers in neighboring nerve roots not involved in the mechanical compression. BACKGROUND DATA: Results from experimental and clinical studies indicate that chronic compression of lumbar nerve roots affects the large myelinated nerve fibers. The majority of nerve fibers involved in the sensation of pain, however, are small afferent nerve fibers. It is therefore of interest to study the effect of compression on large and small sensory afferent channels. Several authors have elucidated the biochemical interaction between disc tissue and nerve roots. Chemical substances in the epidural space can reach the nerve fibers in nerve roots at the same or neighboring lumbar segments. In this way, fibers not involved in the mechanical compression may be affected. METHODS: The small nerve fibers were studied using tests for thermal thresholds (thermotest), and the large myelinated fibers were studied by vibrametry. Forty-two patients were investigated in the symptomatic and the asymptomatic leg, and the results were compared with those of 21 healthy individuals. RESULTS: The thresholds of cold, warmth, and vibration were significantly increased in the dermatome of the compressed nerve root, indicating that large and small sensory nerve fibers were affected. Further, the thresholds were significantly increased in the neighboring dermatomes in the symptomatic and the asymptomatic leg. CONCLUSION: Large and small sensory afferent nerve fibers are affected in lumbar radiculopathy. The increase in sensation thresholds in the ipsilateral neighboring dermatome and in the dermatomes in the asymptomatic leg indicates that adjacent nerve roots are involved in the pathophysiology of sciatica in patients with lumbar disc herniation.     

Photocoagulation in the prevention of retinal detachment in perforating injuries of the eye caused by warfare

Main indications for application of photocoagulation in the prevention of retinal detachment in penetrating eye war injuries were presented. Photocoagulation was performed when intrabulbar foreign body was present, before its extraction and in the cases of traumatic ruptures of sectorial traumatic tractional retinal detachment. Modified photocoagulation by argon laser, with linked spots in two rows was used since it was shown to be clinically the most suitable.     

Neural structures within the sheep temporomandibular joint

To better understand pathologic processes associated with arthritis of the temporomandibular joint (TMJ), detailed information on the innervation of TMJ tissues in normal as well as arthritic joints is needed. The aim of this study was to describe the normal innervation of the sheep TMJ in preparation for using this animal as a model for the study of the effects of arthritis on joint innervation. The macroscopic and microscopic appearance plus the distribution of neural structures within the TMJ were examined using fluorescence histochemistry (glyoxylic acid), immunohistochemistry (calcitonin gene-related peptide), silver, and gold chloride techniques. Joints from 10 mature merino sheep were studied. Calcitonin gene-related peptide-immunoreactive nerve fibers were found in the capsule and the synovial membrane, but not in the disc. Nerve bundles and single nerve fibers in the capsule, synovial membrane, and the peripheral 2 to 3 mm of the disc were stained by glyoxylic acid. Ruffini, paciniform-type, and Golgi organ nerve endings plus free nerve endings were located in the capsule, with the highest density of nerve endings occurring at the site of attachment of the disc to the capsule. The highest density of neural structures (using gold chloride) was in the posterior part of the joint. The highest density of autonomic fibers (using glyoxylic acid) was in the anterior capsule. The highest density of sensory fibers (using calcitonin gene-related peptide) was in the synovial and subsynovial tissues of the anterior capsule. These results confirm the existence of autonomic and sensory nerves in the capsule, synovial membrane, and peripheral disc in healthy adult sheep.     

Course of the optic nerve fibers through the lamina cibrosa in human eyes

BACKGROUND: This study investigated whether regional variations in the course of the optic nerve fibers through the lamina cribrosa may be one of the reasons why the local susceptibility for glaucomatous optic nerve fiber loss differs among the various regions of the optic disc. METHODS: The study included 34 human eyes enucleated because of a malignant melanoma of the peripheral choroid without involvement of the anterior chamber angle or the optic nerve. Anterior-posterior sections through the pupil and the optic disc were histomorphometrically evaluated. In the central region and the peripheral part of the optic disc, we measured the thickness of the lamina cribrosa and the length of the lamina cribrosa "channels" through which the nerve fibers pass. RESULTS: In the peripheral parts of the disc, compared with its central region, the lamina cribrosa was significantly thicker (P < 0.0001, Wilcoxon test), the lamina cribrosa "channels" with the nerve fibers passing through were significantly longer (P < 0.0001), and the ratio of length of the fiber "channels" to the thickness of the lamina cibrosa was significantly higher (P = 0.0001). CONCLUSION: The lamina cribrosa is thicker and the course of the optic nerve fibers through the lamina cribrosa is more curvilinear in the disc pheriphery than in the disc center. These variations in the anatomy of the lamina cribrosa may be one of several factors influencing the regional susceptibility for glaucomatous optic nerve fiber loss within the optic nerve head.     

Use of scanning laser ophthalmoscopy to monitor papilloedema in idiopathic intracranial hypertension

AIMS: To determine the sensitivity of confocal scanning laser ophthalmoscopy (SLO) in detecting clinically significant changes in papilloedema secondary to idiopathic intracranial hypertension (IIH) and the correlation with visual field loss. METHODS: Eight patients--three new, two recurrent, and three chronic cases of IIH--were examined over a 9 month period with SLO (Heidelberg retina tomograph) of optic nerve head and 30-2 Humphrey visual fields (six cases). Optic disc swelling (volume) was assessed in each eye using a circular contour line placed around the swollen optic nerve head on the mean image of three topographic images. Nine volume measurements from single images in each eye of every patient were performed on one occasion to assess repeatability. RESULTS: In the five acute cases optic disc volumes (range 1-16 mm3) decreased with treatment to stable, normal levels. Three of these had mild, reproducible, field defects which resolved. Two chronic cases had stable or fluctuating disc volume with no detectable change in grade of papilloedema and mild field loss. In one case which underwent theco-peritoneal shunting both disc volume and field worsened, indicating therapeutic failure. Both improved postoperatively. CONCLUSIONS: SLO has a high sensitivity for detecting small changes in disc volumes and correlates closely with visual field change in the short term. It can confirm therapeutic failure by detecting stable or increasing disc volume. Decreasing volume may indicate resolution of papilloedema or secondary optic atrophy, so accompanying funduscopy and visual fields remain essential.     

Influence of laser photocoagulation for clinically significant diabetic macular oedema (DMO) on short-wavelength and conventional automated perimetry

The aim of the study was to determine the effect of laser photocoagulation for clinically significant diabetic macular oedema (DMO) on macular visual function as assessed by conventional and short-wavelength automated static threshold perimetry. The sample comprised 24 patients who required laser photocoagulation for clinically significant DMO (mean age 59.75 years, range 45-75 years). One eye of each patient was selected for the study. Patients underwent conventional and short-wavelength perimetry using programme 10-2 of the Humphrey Field Analyser on two separate occasions prior to treatment and subsequently within 1 week of, and at 1, 2, 4 and 12 weeks after, treatment. The pointwise pattern deviation plot was analysed for conventional perimetry and a pointwise horizontal and vertical hemifield asymmetry analysis was derived for short-wavelength perimetry (thereby negating the influence of pre-receptoral absorption). The extent of sensitivity loss was determined by counting the number of stimulus locations with statistical probability levels of p less than 0.05. Group mean log minimum angle of resolution (logMAR) visual acuity was largely unchanged over the course of the study. Conventional perimetry showed an increase in the group mean number of abnormal contiguous stimulus locations from 2.4 (SD 4.3, range 0-14) immediately prior to treatment, to 12.4 (SD 7.8, range 0-30) within 1 week of treatment; at 3 months post-treatment, the group mean number of abnormal contiguous stimulus locations was 8.1 (SD 6.5, range 0-20). A similar but less pronounced change was found for short-wavelength perimetry. The spatial position of the post-treatment localised sensitivity loss corresponded with the area of retinal photocoagulation. Despite proven benefit in the stabilisation of visual acuity, laser photocoagulation for clinically significant DMO invariably results in a localised loss of perimetric sensitivity within 10 degrees eccentricity of the fovea. Evidence for the value of laser therapy for clinically significant DMO must be re-examined.     

Early treatment of posterior retinopathy of prematurity: a controlled trial

OBJECTIVE: The purpose of the study is to assess the possible benefits of early laser treatment for posterior retinopathy of prematurity (ROP) and to provide data concerning the natural history of posterior ROP. DESIGN: The study design was a prospective, multicenter, randomized trial. PARTICIPANTS: A total of 19 infants with prethreshold posterior ROP were studied. INTERVENTION: Randomization to immediate indirect laser photocoagulation or observation, with application of laser photocoagulation for those control eyes reaching threshold disease, was performed. MAIN OUTCOME MEASURES: Patients were assessed at 3 months and the anatomic outcome recorded along with any adverse treatment effects. RESULTS: An unfavorable structural outcome developed in 3 (16%) of 19 early treatment eyes compared with 3 (18%) of 17 for those treated only if threshold disease was reached. Of the 17 control eyes, 15 (88%) reached threshold disease. Progression to threshold occurred within 1 week in all but two eyes. All 12 control eyes with posterior ROP and any amount of extraretinal fibrovascular proliferation progressed to threshold disease. CONCLUSIONS: Although the number of patients studied is too small to reach statistical significance, the likelihood of a favorable outcome for eyes with prethreshold posterior ROP treated immediately with laser photocoagulation is comparable to that obtained by withholding treatment until threshold disease is reached. There is a high probability of progression from prethreshold to threshold disease, usually within 1 week or less.     

Racial and ethnic disparities in the use of cardiovascular procedures: associations with type of health insurance

This is the first report showing VIP fibers in the optic chiasm and the optic nerves of intact rats. These fibers form a fan-shaped dorso-medial bundle in the optic nerves. After colchicine injection into the vitreous body VIP fibers could be followed farther in the optic nerve toward the eye when compared to intact rats. After removal of eyes (enucleation) the VIP fiber-bundle became more prominent and VIP immunoreactive perikarya appeared in the supraoptic and para ventricular nuclei. When five-nine months after the enucleation Phaseolus vulgaris leucoagglutinin was administered to the paraventricular or supraoptic area, the anterogradely transported tracer was demonstrated in the optic nerve. These observations suggest the existence of a hypothalamic projection to the eye, which is, at least in part, VIP immunoreactive.     

Prevention of retinal detachment in Wagner-Stickler disease. Comparative study of different methods. Apropos of 22 cases

Prophylactic treatment in patients presenting Wagner-Stickler disease has not been yet well defined. We retrospectively studied twenty-two patients who had a retinal detachment on the first eye. Among the ten patients treated by peripheral confluent laser photocoagulation, five had a retinal detachment after a mean follow-up of fifteen months; with a 42% rate of spontaneous retinal detachment bilateralization, we can conclude that laser therapy has not been efficient. Four patients treated by focal or circular laser photocoagulation, cryotherapy or vitrectomy developed retinal detachment. Eight eyes treated by a preventive encircling scleral buckle did not develop retinal detachment, with a mean follow-up of twenty-one months. This follow-up is still too short, but greater than the mean bilateralization delay. Per and postoperative complications had no consequences.     

Differential inhibition of human prostaglandin endoperoxide synthase-1 and -2 by nonsteroidal anti-inflammatory drugs

PURPOSE: The authors determined the effect of photocoagulation of drusen on visual acuity and progression to subretinal neovascular membranes (SRNV). METHODS: One of paired eyes was randomized to photocoagulation with other eye to control in 27 patients having symmetrical maculopathy and visual acuities, aged 46 to 81 years (mean, 69.7 years); follow-up 1 to 6 years (mean, 3.2 years). RESULTS: Final visual acuity was improved in treated eye or decreased in control eye in 12 patients, equal in 13 patients, and decreased in treated eye in 2 patients (P < 0.006). Progression to SRNV was less with treatment. CONCLUSION: Laser photocoagulation of confluent soft macular drusen may improve long-term visual prognosis.     

Characterisation of the infarct-limiting effect of delayed preconditioning: timecourse and dose-dependency studies in rabbit myocardium

BACKGROUND: Although the choroidal neovascularization (CNV) is a common pathologic feature of a number of different eye diseases, its pathological mechanisms have not been fully elucidated. We investigated the expression of vascular endothelial growth factor (VEGF) in CNV using an experimental primate model. METHOD: CNV was induced by intense laser photocoagulation in four monkey eyes. Single eyes were enucleated at 1, 3, 7 or 14 days after photocoagulation and examined immunohistochemically for VEGF, macrophage antigen, von Willebrand factor and glial fibrillary acidic protein (GFAP). Expression of VEGF mRNA was examined by in situ hybridization. RESULTS: One day after photocoagulation, the normal structure of the outer portion of the retina and the inner portion of the choroid was destroyed. Three days after photocoagulation, choroidal vascular endothelial cells migrated into the subretinal space through the defect in Bruch's membrane. Increased expression of VEGF was detected in the accumulating macrophages, migrating retinal pigment epithelial (RPE) cells and Müller cells. Maximal expression of VEGF was observed between 3 and 7 days after wounding, and many newly formed vessels extended into the subretinal space 7-14 days after photocoagulation. CONCLUSION: VEGF derived from RPE cells, macrophages and Müller cells may play a role in the formation of CNV.     

A long-term course of experimentally produced choroidal neovascularization in the rat

We studied morphologically a long-term course of experimental choroidal neovascularization (ChNV) induced by krypton laser photocoagulation in the rat retina. Fifty-two weeks after photocoagulation, ChNV was enveloped completely by the retinal pigment epithelium. Vascular endothelial cells of ChNV were thin, with many fenestrations and wide lumen. The ChNV maintained the morphological characteristics of mature leaky capillaries similar to choriocapillaris. The lumen of the neovascularizations tended to be compressed by massive collagen fibers produced by the retinal pigmented epithelium. We found that experimental ChNV in the rat retina retains the characteristics of leaky capillaries for a long time unlike that in the monkey ChNV.     

Application of Raney nickel to measure adducts of styrene oxide with hemoglobin and albumin

BACKGROUND: Although peripheral cryotherapy decreases the incidence of unfavorable anatomic outcomes in threshold retinopathy of prematurity (ROP), apnea, bradycardia, and lid edema can occur. Argon laser indirect ophthalmoscope photocoagulation has been used as an alternative to cryotherapy, with fewer adverse effects. Retinal lesions placed with diode lasers are deeper than similar argon laser lesions, and it is not known whether this difference could influence the response to ablative therapy. METHODS: Patients were enrolled under a prospective, randomized protocol. One eye of each patient with symmetric, threshold ROP was treated with an 814/815 nm diode laser, while the other eye was treated with cryotherapy. Patients with asymmetric diseases also were randomized for treatment in the threshold eye. RESULTS: Nineteen infants (33 eyes) were treated, ranging from 485 to 863 g birth weight (23 to 27 weeks gestational age); 18 patients (32 eyes) were followed for 3 months or longer. Four patients (8 eyes) had bilateral zone 1 disease. Postconceptional age was 36 to 45 weeks at the time of treatment. The diode laser treatment was better tolerated than cryotherapy, and the treatment apparatus was more easily transported. Apneic episodes requiring intubation resulted from two cryotherapy sessions but no diode laser sessions. Five cryotherapy-treated eyes required retreatment because of persistent disease with adjacent skip areas. In the group followed for 3 to 15 months, 1 cryotherapy-treated eye and 1 diode laser-treated eye progressed to stage 5 retinal detachment. CONCLUSION: Compared with cryotherapy, the diode laser was more convenient, technically easier to administer, and better tolerated by the patient. Although the number of patients was too small for meaningful statistical analysis of outcome, diode laser peripheral retinal ablation appeared to be as effective as cryotherapy for the treatment of threshold ROP.     

A case of nonarteritic anterior ischemic optic neuropathy with cilioretinal artery occlusion

We report a case of nonarteritic anterior ischemic optic neuropathy (AION) with cilioretinal artery occlusion. The patient was a 61-year-old man with sudden visual loss in his right eye. Funduscopy showed pale swelling of the entire optic disc with retinal ischemic edema of the upper half of the retina, and fluorescein angiography revealed faint filling of the dye in the optic disc in the retinal arterial phase, and dye staining of the optic disc in the late phase. We initially diagnosed the disease as AION with branch retinal artery occlusion, but systemic administration of a corticosteroid and urokinase were ineffective and the optic disc became atrophic. As the optic disc swelling decreased and the course of arteries in the optic disc became clear, we repeated fluorescein angiography which proved that the involved upper retinal artery was a cilioretinal artery having earlier dye appearance than the lower retinal artery. Thus, we finally diagnosed the disease as AION with cilioretinal artery occlusion. We believe that Hayreh's view that AION may result from occlusion of the posterior ciliary artery is supported by the intraocular findings in this case.