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Biomedical subjects

G Richard

Publications and source records attributed to G Richard.

At least 19 recordsLinked to original sources
PubMed2006

Glaucoma progression is associated with decreased blood flow velocities in the short posterior ciliary artery.

BACKGROUND: An altered perfusion of the optic nerve head has been proposed as a pathogenic factor in glaucoma. AIM: To investigate potential differences in the ocular haemodynamics of patients having glaucoma with progressive versus stable disease, as well as healthy volunteers. METHODS: Peak-systolic velocity (PSV), end-diastolic velocity (EDV) and resistivity index in the short posterior ciliary artery (SPCA), central retinal artery (CRA) and ophthalmic artery were recorded in 114 consecutive patients having glaucoma with an intraocular pressure (IOP) < or =21 mm Hg, as well as in 40 healthy volunteers, by colour Doppler imaging (CDI). RESULTS: Of the 114 patients with glaucoma, 12 showed glaucoma progression (follow-up period: mean 295 (standard deviation (SD) (18) days). CDI measurements in these patients showed decreased PSV and EDV in the SPCA (p<0.001 and p<0.05, respectively) and decreased PSV in the CRA compared with patients with stable glaucoma and healthy controls (p<0.05). No differences in flow velocities were found for the ophthalmic artery. IOP and systemic blood pressure was similar in all the three groups. CONCLUSIONS: Progressive glaucoma is associated with decreased blood flow velocities in the small retrobulbar vessels supplying the optic nerve head. The detected difference could represent a risk factor for progression of glaucomatous optic neuropathy.

Adult↗
PubMed2006

[Status of TTT in the therapy for CNV].

Transpupillary thermotherapy (TTT) and photodynamic therapy (PDT) are recent treatment options for choroidal neovascularisation (CNV). In PDT a photochemical reaction is induced by the injection of a photosensitising substance. In contrast to this, TTT is a non-invasive photothermal treatment option for CNV and choroidal tumours. It leads to a low-grade-hyperthermia with consecutive induction of metabolic processes and production of heat-shock proteins in order to restore cellular homeostasis. Classical laser coagulation as recommended by the Macular Photocoagulation Study Group produces a photocoagulative effect with significant tissue hyperthermia and prompt visual loss. For classic CNV, PDT represents an established therapy option. Positive results of the treatment of occult CNV by PDT have enlarged the use of PDT to this kind of CNV. TTT represents an economic therapy modality for (mainly) occult CNV. The effect for visual outcome varies in different studies. The results are shown in a .

Choroidal Neovascularization↗
PubMed2005

Volumetric colour Doppler imaging: a useful tool for the determination of ocular blood flow in glaucoma patients?

PURPOSE: Disturbed ocular haemodynamics are discussed to contribute to the pathogenesis of glaucoma. Up to now there is no method available allowing direct determination of blood flow, which is the most relevant dimension for studies on haemodynamics. In this study, volumetric colour Doppler imaging (vCDI) is evaluated systematically in glaucoma patients. METHODS: A Siemens Elegra ultrasound set-up with a linear 7.5 MHz probe was used for all CDI measurements. For vCDI, the cross-sectional area of a vessel and the flow velocity is determined. From both these parameters blood flow can be calculated. Ocular pulse amplitude (OPA) was assessed by the method of Langham using a pneumatic applanation tonometer. RESULTS: (1) Velocity measurements using CDI in the ophthalmic artery and central retinal artery were highly reproducible (n=20). In contrast, reproducibility of vCDI measurements was low (n=20). Reproducibility improved if five vCDI measures were averaged. (2) Results from two different CDI-operators did not differ regarding the velocity measurements, but there was a difference in vCDI measurements (n=20). (3) Results from vCDI did not correlate with measurements of OPA in 69 patients. (4) In 15 patients, vCDI failed to detect changes of ocular perfusion induced by the application of dorzolamide. CONCLUSION: vCDI is not applicable in ophthalmology at present.

Adult↗
PubMed2005

[OCT in epiretinal gliosis].

Biomorphometric studies using optical coherence tomography (OCT) in patients with epiretinal membranes reveal a highly reflective membrane, a significant foveal thickening, loss of the foveal depression, and the presence of intraretinal cysts. Epiretinal membranes are more frequently totally adherent than separated with focal points of adherence. Visual acuity correlates with foveal thickness prior to and 6 months after vitrectomy and surgical removal of epiretinal membranes. Foveal thickening regresses postoperatively, but normal values are seldom reached. Marked foveal thickening, nonexistent foveal depression, and extensive cyst formation are supposed to correlate with a rather poor visual outcome. OCT plays a pivotal role in the differential diagnosis of pseudomacular hole in epiretinal membranes and of full-thickness macular hole. In addition to biomicroscopy and fluorescein angiography, OCT images provide valuable information for a structural assessment of the macula, especially in evaluating the postoperative course of macular surgery.

Epiretinal Membrane↗
PubMed2005

[Development of an epiretinal prosthesis for stimulation of the human retina].

Degenerations of the outer retina in retinal diseases such as retinitis pigmentosa lead to blindness due to photoreceptor loss. A therapeutic option for visual rehabilitation is presently not available. Over the last few years, a retinal prosthesis has been developed and its use has been tested in animal experiments as well as in humans. With the epiretinal implant images of the environment are taken by a camera, these data are transmitted to an intraocular encoder, and the retina is electrically stimulated by a retinal stimulator placed epiretinally. The stimulation electrodes are placed as flexible microcontact electrodes by pars plana vitrectomy in an epimacular position. The threshold is determined by stimulations of increasing amplitudes. Initial results of acute epiretinal stimulation using an epiretinal implant in legally blind patients demonstrate that acute epiretinal stimulation of the human retina is feasible and safe.

Animals↗
PubMed2005

Results of radiotherapy of subfoveal neovascularization with 16 and 20 Gy.

PURPOSE: In a nonrandomized, prospective study the efficacy of radiotherapy with 16 and 20 Gray (Gy) for subfoveal neovascularization in age-related macular degeneration (ARMD) was analysed. MATERIAL AND METHODS: From 1996 to 1998, 63 eyes were irradiated with 16 Gy and 38 eyes with 20 Gy for exudative ARMD. A total of 12 eyes had classic ARMD, 89 eyes occult ARMD, median baseline visual acuity (VA) was 6/30 (range: 3/60-6/9.5), median age was 78 years. Risk factors (type of ARMD, baseline VA) were evenly distributed in both groups. Median follow-up was 1.3 years (range: 4 months-4.7 years). VA of +/-1 line or better and unchanged size and activity of the membrane in fluorescein angiography were defined as stable. Actuarial methods were used. RESULTS: Median loss of VA was -3 lines (range: -14 to +5), neovascularization remained unchanged or decreased in size and activity in 35 eyes. At 18 months, the probability of stabilized VA was 0.4 (95% confidence interval (CI): 0.3-0.5), at 24 months 0.3 (95% CI: 0.2-0.4). Radiation dose, type of ARMD or baseline VA had no significant impact on outcome of VA and membrane size and activity (P>0.05). Side effects were mild and transient increased tearing. CONCLUSION: In this study, the results after radiotherapy were comparable to the natural course of the disease. An impact of radiation dose (16 vs 20 Gy) on stabilizing visual acuity and subfoveal neovascularization could not be shown. The results of studies on dose escalation using very small fields and high radiation doses should be awaited.

Aged↗
PubMed2005

[Radial optic neurotomy in ischemic central retinal vein occlusion].

BACKGROUND: Loss of visual acuity due to ischemic retinal vein occlusion (RVO) is still a major problem in ophthalmology. Prognosis is poor and loss of vision is a severe risk. New approaches for treatment like systemic fibrinolysis and surgical procedures have been suggested. PATIENTS AND METHODS: In a clinical trial 8 patients with ischemic CRVO underwent surgical decompression. Strict criteria of inclusion were maintained. Radial optic neurotomy (RON) was performed 0.25-5 months after retinal vein occlusion. Follow up-time was 3 months. Visual acuity and incidence of typical complications after RVO were the main points of interest in our scientific evaluation. RESULTS: Visual acuity improved significantly after the surgical procedure. For ischemic CRVO EDTRS charts increased from logMAR 1.0 (decimal 0.17) to 0.68 (0.30) at 3 months after surgery. Surgical or early complications did not occur within 3 months. The recovery of retinal blood flow during fluorescein angiography was investigated in 75 % of the patients. A resolution of non perfusion-areas could be detected in 50 % of the eyes. CONCLUSIONS: For patients with retinal vein occlusion RON seems to be a safe and feasible procedure. The results indicate the potential to improve visual acuity while typical complications due to surgery or vein occlusion did not occur during the first three months.

Adult↗
PubMed2005

[NF2: ocular, neural and genetic manifestations].

Neurofibromatosis 2 is an autosomal-dominant disease, which is characterized by vestibular schwannomas, cataract, retinal hamartomas as well as tumors of the peripheral and central nerve system, demonstrating a variety of expression. The ophthalmologist plays an important role in making the diagnosis, as several ocular manifestations may be shown during childhood, before tumors of the central nerve system become symptomatic. An early diagnosis of NF 2 may prevent deafness by early surgical intervention. Due to primary and secondary reasons such as age-related processes, different sensations like hearing or vision may be compromised. Neuropathy may lead to vestibular disturbances and loss of muscle control. Therapeutic options include cataract surgery, implantation of cochlear or brainstem implants as well as conservative therapy of the ocular surface in paresis of the VIIth cranial nerve or learning to read from the lips. The human NF2 gene was cloned from chromosome 22 in 1993. The major part of the genetic alterations described so far are point mutations as well as deletions or insertions in or around the exons. Geno-phenotype correlations allow some predictions of the course of the disease to be made.

Adolescent↗
PubMed2005

Netherton syndrome: report of two Taiwanese siblings with staphylococcal scalded skin syndrome and mutation of SPINK5.

Netherton syndrome (NS) is a severe autosomal recessive ichthyosis. It is characterized by congenital ichthyosiform erythroderma, trichorrhexis invaginata, ichthyosis linearis circumflexa, atopic diathesis and frequent bacterial infections. Pathogenic mutations in SPINK5 have recently been identified in NS. SPINK5 encodes lymphoepithelial Kazal-type-related inhibitor (LEKTI), a new type of serine protease inhibitor involved in the regulation of skin barrier formation and immunity. We report two Taiwanese brothers with NS. The patients had typical manifestations of NS with an atopic diathesis and recurrent staphylococcal infections, including staphylococcal scalded skin syndrome (SSSS) since birth. Horny layers were obtained by skin surface biopsy for electron microscopy from lesional skin of both patients and from normal controls. All 33 exons and flanking intron boundaries of SPINK5 were amplified for direct sequencing. The ultrastructure of the stratum corneum (SC) was characterized by premature degradation of corneodesmosomes (CDs) with separation of corneocytes. A homozygous 2260A --> T (K754X) mutation of SPINK5 was found in both patients. Staphylococcal exfoliative toxin A (ETA) is a serine protease capable of cleaving desmoglein 1, an important adhesive molecule of CDs, and can cause separation of the SC, resulting in SSSS. The premature degradation of CDs found in our patients may be attributable to insufficient LEKTI, and possibly also to colonization/infection of ETA-producing Staphylococcus aureus. Mechanisms involved in the pathogenesis of the skin barrier defect in NS are proposed. Further study is needed to prove this hypothesis.

Base Sequence↗
PubMed2005

A new, recurrent mutation of GJB3 (Cx31) in erythrokeratodermia variabilis.

BACKGROUND: Erythrokeratodermia variabilis (EKV) is an autosomal dominant or recessive genodermatosis characterized by the coexistence of randomly occurring, transient, erythematous patches and hyperkeratosis of the skin. The disorder has been mapped to chromosome 1p35.1 but is genetically heterogeneous. EKV may be caused by pathogenic mutations in one of two neighbouring connexin genes, GJB3 and GJB4, encoding the gap junction proteins Cx31 and Cx30.3, respectively. Twelve distinct mutations identified to date cluster either at the cytoplasmic amino-terminus or in the four transmembrane domains. OBJECTIVES: To report a large family with EKV and an unrelated sporadic case. METHODS: DNA amplification and mutation analysis, followed by denaturing high-performance liquid chromatography to confirm the segregation of the mutations in the two families with EKV. RESULTS: A novel, recurrent GJB3 mutation (625C-->T; L209F) was identified in the family with EKV and in the unrelated sporadic case. CONCLUSIONS: This mutation is the first to affect a conserved residue in the cytoplasmic carboxy-terminus of any connexin gene with a cutaneous phenotype, emphasizing its structural and/or functional importance.

Adult↗
PubMed2004

[Optical coherence tomography in optic pit and associated maculopathy].

BACKGROUND: Of patients with an optic pit 30% develop an associated maculopathy of unknown origin. We report on 8 patients with an optic pit and associated maculopathy evaluated by optical coherence tomography (OCT) for detection of structural retinal changes and indications for the pathogenesis. PATIENTS AND METHODS: A total of 8 patients (mean age 25 years) suffering from an optic pit and associated maculopathy were evaluated by biomicroscopy, fluorescein angiography (FLA) and OCT and the results were compared. RESULTS: Visual acuity was on average 0.5 (0.05-0.8). Funduscopy revealed a macular elevation. In clinically suspected 'pseudo' macular hole, OCT revealed foveal schisis. OCT demonstrated a retinal detachment with a typical convex schisis of the outer retinal layer (n=6), and three patients showed a neurosensory detachment with (n=2) and without (n=1) intraretinal cystoid formation. CONCLUSION: The typical macular schisis pattern in OCT in optic pit with serous maculopathy helps to differentiate this condition from other macular elevations.

Adolescent↗
PubMed2004

[OCT in macular holes].

The traditional Gass classification of macular holes can now be supplemented by additional and more detailed morphologic information obtained with optical coherence tomography (OCT). The perifoveal vitreous detachment and subsequent anterior foveal traction is considered to be the primary pathomechanism of macular hole formation. In cases of persistent traction on the fovea it may lead to foveal dehiscence. A possible explanation for intraretinal cyst formation may be secondary vitreous body fluid accumulation within the retina. A classification of macular holes based on additional information from OCT images is possible. Thus, OCT is a valuable tool for differential diagnosis of a pseudo macular hole versus macular hole, precise stage classification, therapy decision making process, outcome control after macular surgery, and prognosis prediction.

Diagnosis, Differential↗
PubMed2004

[Optical coherence tomography for macular edema. Classification, quantitative assessment, and rational usage in the clinical practice].

Optical coherence tomography (OCT) allows for morphological assessment of macular edema of various origins by producing two-dimensional images of the retina. In addition, retinal thickness can be measured quantitatively. In diabetic maculopathy, damage of the blood-retinal barrier can be indirectly assessed by locating the intraretinal fluid accumulation and the progress of maculopathy from diffuse to cystoid edema and even rupture of the retinal structure can be described as well as the formation of neurosensory retinal detachment with subretinal fluid. Increase of retinal thickness correlates with decrease in visual acuity. Detailed interpretation of OCT images can replace fluorescein angiography in certain cases, as has been shown for uveitis. In order to obtain correct classification of macular disease in routine clinical use, all images have to be completely assessed and compared to previous investigations and to the measurements of the fellow eye. More accurate normal values of retinal thickness and volume can be expected in the future. The importance of OCT in routine clinical assessment of macular edema will most probably continue to grow.

Diagnosis, Differential↗
PubMed2004

[Transpupillary thermotherapy for subfoveal choroidal neovascularization. A 9-month follow-up].

PURPOSE: The purpose of this study was to evaluate the efficiency, stability, and safety of transpupillary thermotherapy as a treatment of subfoveal occult choroidal neovascularizations (CNV) in age-related macular degeneration. METHODS: Transpupillary thermotherapy (TTT) was performed in 40 patients with uni- or bilateral predominantly occult CNV. Laser light derived from an infrared diode laser at 810 nm was used to apply spots for a duration of 60 s. A complete ophthalmic examination was performed prior to and 9 months after the treatment. RESULTS: After 9 months, visual acuity remained stable in 65% (+/-2 lines). In 35% of the patients TTT could not prevent further visual loss. Retinal leakage, assessed by fluorescein angiography, stabilized in 67.5% of the treated patients. CONCLUSIONS: The present data show stabilization of visual acuity in 65% after TTT. Compared to the natural course of occult and mixed subfoveal CNV, these data give some evidence for patient benefit after TTT.

Aged↗
PubMed2004

Reproducibility of blood flow velocity measurements using colour decoded Doppler imaging.

BACKGROUND: It is taken for granted that glaucomatous damage is caused by changed haemodynamics of the retrobulbar vessel system besides other factors such as, for example, an elevated intraocular pressure. This was proven by various studies in which glaucoma patients were shown to have a changed retrobulbar blood flow velocity. In this study, the reliability of measurements of retrobulbar vessel perfusion by colour decoded Doppler imaging (CDI) was evaluated. PATIENTS AND METHODS: A total of 18 healthy volunteers and 15 patients with various glaucoma types were enrolled in this study. Using a CDI system, type Siemens Sonoline Elegra with a combined applicator (7.5L40), retrobulbar vessel perfusions of the ophthalmic artery, the short posterior ciliary arteries, and the long posterior ciliary arteries of each patient were measured six times. In each measurement, pulse amplitude, end-diastolic velocity, maximum systolic velocity, pulsatility index, and resistivity index of the vessels were determined. The reproducibility of measurements was evaluated by the calculation of the intraclass correlation coefficient (ICC) for each parameter. RESULTS: The ICCs for the ophthalmic artery varied from 0.89 to 0.98, for the short posterior ciliary artery from 0.75 to 0.91, and for the long posterior ciliary artery from 0.77 to 0.99 in both the groups. CONCLUSIONS: The ICCs of the repeated measurements reflect a good reproducibility for both the groups with assumed different retrobulbar perfusion. These findings are prerequisites for the use of CDI in clinical practice and research.

Blood Flow Velocity↗
PubMed2004

[Arteriovenous sheathotomy in venous thrombosis].

BACKGROUND: The pathogenesis of branch retinal vein occlusion (BRVO) seems to differ from that of central retinal vein occlusion (CRVO). Arteriosclerotic and anatomic aspects suggest that arteriovenous crossing of vessels may play a significant role. New procedures like arteriovenous decompression have been proposed to be a suitable form of treatment. PATIENTS AND METHODS: In a clinical trial, 12 patients with ischemic BRVO underwent surgical decompression. Strict criteria of inclusion were maintained. Arteriovenous sheathotomy (AVS) was performed 0.5 - 6 months after retinal vein occlusion. Follow up-time was 3 months. Visual acuity and incidence of typical complications after RVO were the main aspects of interest in the scientific evaluation. RESULTS: After surgical AVS, visual acuity increased significantly from logMAR 0.74 (decimal 0.18) to 0.56 (0.32) in EDTRS charts. Surgical or early complications did not occur during the 3-month control period. Improvement of retinal blood flow during angiography was demonstrated in 75 % of the patients. In 50 % of the patients all non-perfusion areas had disappeared. CONCLUSIONS: For patients with retinal vein occlusion, AVS seems to be a safe and feasible procedure according to the pathogenesis of branch occlusion. Our results suggest that AVS has the potential to improve visual acuity while typical complications due to surgery or vein occlusion do not occur during the first three months.

Adolescent↗
PubMed2004

[Ocular hemodynamics in normal tension glaucoma: effect of bimatoprost].

BACKGROUND: Altered ocular perfusion plays a role in the pathophysiology of normal tension glaucoma. Prostaglandin-like substances are very effective in lowering intraocular pressure. Less data are available regarding the influence of these compounds on ocular perfusion. In the present study the effects of bimatoprost, which has recently been shown to increase the vascular tone of ciliary arteries in vitro, on the blood flow velocity are investigated. PATIENTS AND METHODS: n = 9 eyes from 9 normal tension glaucoma patients were subjected to color Doppler imaging (CDI) before and during a 3 - 5 week therapy with bimatoprost. RESULTS: Bimatoprost reduces intraocular pressure from 14.0 +/- 0.4 to 11.0 +/- 0.5 mmHg (n = 9; P < 0.001). Systolic as well as diastolic blood flow velocities, resistive index (RI) and pulsatility index (PI), measured by CDI, were unaltered in the presence of bimatoprost. DISCUSSION: Bimatoprost does not influence blood flow velocities in the retrobulbar vessels. The in vitro observation of increased vascular tone in the presence of bimatoprost seems not to be relevant for ocular hemodynamics.

Amides↗