Biomedical subjects
Publications and source records attributed to P Hamard.
We report a case of a 71-year-old man with sequential visual loss within 3 days due to giant cell arteritis confirmed by a temporal artery biopsy. The anterior ischemic optic neuropathy was associated with cilioretinal artery occlusion on the right eye. He improved after intravenous corticosteroid therapy. Clinical characteristics and treatment are discussed.
The spatial distributions of leaf expansion rate, cell division rate and cell size was examined under contrasting soil water conditions, evaporative demands and temperatures in a series of experiments carried out in either constant or naturally fluctuating conditions. They were examined in the epidermis and all leaf tissues. (1) Meristem temperature affected relative elongation rate by a constant ratio at all positions in the leaf. If expressed per unit thermal time, the distribution of relative expansion rate was independent of temperature and was similar in all experiments with low evaporative demand and no water deficit. This provides a reference distribution, characteristic of the studied genotype, to which any distribution in stressed plants can be compared. (2) Evaporative demand and soil water deficit affected independently the distribution of relative elongation rate and had near-additive effects. For a given stress, a nearly constant difference was observed, at all positions of the leaf, between the relative elongation rates of stressed plants and those of control plants. This caused a reduction in the length of the zone with tissue elongation. (3) Methods for calculating cell division rate in the epidermis and in all leaf tissues are proposed and discussed. In control plants, the zone with cell division was 30 mm and 60 mm long in the epidermis and in whole tissues, respectively. Both this length and relative division rate were reduced by soil water deficit. The size of epidermal and of mesophyll cells was nearly unaffected in the leaf zone with both cell division and tissue expansion, suggesting that water deficit affects tissue expansion rate and cell division rate to the same extent. Conversely, cell size of epidermis and mesophyll were reduced by water deficit in mature parts of the leaf.
Neovascular glaucoma is a dreadful pathology with a rapid spontaneous evolution responsible for painful and blind eye. The main cause is an anterior neovascular proliferation following a broad retinal ischemia. Early diagnosis and treatment are required in order to maintain a good visual status and a satisfactory IOP control with medical, surgical or cylodestructive procedures. In any case, the treatment of the retinal ischemia has to be performed. One must keep in mind that the most efficient way to avoid the incidence of neovascular glaucoma is a strict control of clinical situations potentially responsible for retinal ischemia, namely VRO in elderly patients and diabetic retinopathy in younger patients.
Three trabeculectomy failures raises the delicate problem of refractory glaucoma with unresponsive ocular hypertony. The therapeutic strategy requires first a careful assessment of the reasons for the previous failures (internal or external obstacles to filtration which might have responded to preventive treatment), then, depending on the patient's age, type of glaucoma, anatomic status of the ocular structures and the visual potential of the eye, a choice has to be made between different surgical techniques aimed at favoring aqueous humor evacuation (trabeculectomy associated with antimetabolites or drainage implant) or destruction of the ciliary body to reduce intraocular pressure by limiting the production of aqueous humor. Choosing between these two possibilities is not an easy task as success rates are highly variable on such eyes and complications are frequent, leading to lower visual acuity in 30 % of the cases. These salvage procedures recall that first line trabeculectomy must be optimized in all cases.
PURPOSE: To evaluate the success rate of contact diode transscleral cyclophotocoagulation (TSCPC) in pediatric refractory glaucoma. PATIENTS: and method: Twenty-eight eyes of 28 patients (age range 5 months to 26 years) with medical and surgical refractory pediatric glaucoma due to primary congenital glaucoma (group 1, 20 eyes) or aphakic congenital glaucoma (group 2: 8 eyes), were included in this retrospective study. All eyes underwent one or more TSCPC with the diode laser (Oculight SLX, Iris Medical) with a minimal follow-up of 2 months. Success was defined as intraocular pressure (IOP) between 6 and 20 mmHg after one or more procedures, with no increase in medical hypotensive therapy, and no progression to another hypotensive procedure. RESULTS: Mean baseline IOP was 29.4 +/- 7.8 mmHg (range 25 to 60 mmHg) and mean follow-up was 10.3 +/- 6.9 months (range 2 to 26 months). Success rates evaluated at 6 and 12 months (Kaplan Meier survival curves) were 54.4% and 27.7% respectively, with one-third of the eyes retreated once or more. These success rates were similar in both groups with a mean baseline IOP decrease of 38.9 +/- 15.9%. Postoperative uncontrolled hypertony occurred in the first 3 months in 6 (21.4%) eyes, leading to surgical IOP management. Other complications were decrease in visual acuity (14.3%), inflammation (25.5%) and phthisis (3.5%). CONCLUSION: TSCPC with the diode laser is a disappointing procedure for the management of refractory pediatric glaucoma, with poor mid-term IOP control and high incidence of complications including severe uncontrolled IOP increase. For these reasons, this cyclodestructive procedure should be considered as a last resort therapy for patients with refractory pediatric glaucoma.
We reported a retrospective study of 27 children (mean age = 10 years), who presented a loss of vision due to an acute optic neuritis, between 1982 and 1997. The symptoms ar more likely bilateral in children, and frequently associated with systemic viral infection or hepatitis B vaccination. Multiple sclerosis occurs approximately in 20 p. cent of the cases, i.e. less frequently than by adults. Magnetic resonance imaging is now systematic: in 20 children hyperintense nodular abnormalities in a various distribution was demonstrated by 9 children. During the follow-up, 23 eyes of 27 have an excellent recovery of vision, but 4 patients have developed multiple sclerosis. Corticotherapy was uses in 23 cases, in the form of methylprednisolone intravenous flashes in 14 cases.
PURPOSE: The aim of this retropective study is to evaluate and to compare in glaucoma patients, the mid-term results of the non penetrating deep-sclerectomy (NPDS) with collagen implant or with per operative application of 5 fluorouracile (5 FU). MATERIAL AND METHODS: The aim of the NPDS, a new filtering surgical procedure, is to remove under a scleral flap the Schlemm's canal and the juxtacanalicular trabecular meshwork responsible for the outflow resistance in order to obtain a sub-conjunctival filtration of the aqueous humor with no opening of the anterior chamber. Forty-two open angle glaucoma patients with uncontrolled intra-ocular pressure and with no risk factor of bleb fibrosis, underwent a NPDS. In 27 eyes (group 1) a sponge soaked with 5 FU (50 mg/ml) was applied for 5 minutes in the scleral bed, and in 15 eyes (group-2) a collagen implant (Staar*) was sutured in the scleral bed. A complete ophthalmologic examination was performed on days 1, 8, months 1,2,3 and each 3 months until the end of the follow-up. In case of increased IOP, goniopuncture with the Nd: YAG laser was performed at any time of the post operative period. RESULTS: The mean intra-ocular pressure (IOP) significantly decreased from 23.5 +/- 5.1 mmHg to 15.5 +/- 2.9 at 11.1 +/- 5.6 months follow-up (group 1, p < 10(-3)) and from 22.6 +/- 6.9 Hg to 16.2 +/- 3.9 mmHg at 8.8, 3.6 months follow-up (group 2, p < 10(-3)) with a significant decrease in the medical treatment (p < 10(-3)). The Kaplan Meier probability of success (IOP < or = 20 mmHg without treatment and with no visual field deterioration) at 6 and 12 months was similar in both groups: 57.3% (group 1) and 66.0% (group 2) with a mean decrease in IOP of 30%. Goniopuncture had to be performed in more than one third of case in each group and was effective to control the IOP in half of the cases. No complication related to hypotony or inflammation occured in the post operative period. CONCLUSION: NPDS is an interesting alternative to the classical trabeculectomy since the post operative complications are markedly reduced. However, the mid-term control in IOP appears to be slightly lower. The use of a collagen device does not lead to better control in IOP as compared to the use of a sponge of 5 FU.
Glaucoma is a common ocular disorder; a high intraocular pressure is observed in the majority of glaucoma (HIOPG) cases, but some patients have low-tension glaucoma (LTG). In the literature, some works link LTG and migraine, which is speculative of a potential role of a vasospastic factor or diathesis common to migraine and LTG. Using a standardized questionnaire based on International Headache Society (IHS) criteria, we investigated 954 glaucoma patients; 320 (33.5%) described a headache (migraine or tension-type headache) and 240 (25.1%) presented the IHS criteria for migraine. Migraine prevalence was not significantly different between HIOPG and LTG patients (22.8% and 32%, respectively) in this study.
PURPOSE: To evaluate the new threshold strategies of the Humphrey Field Analyser, SITA Standard and SITA Fast, in normals and glaucoma patients. METHODS: Fifty healthy volunteers and 50 glaucoma patients were tested twice with three algorithms: Full Threshold, SITA Standard and SITA Fast in two sessions. The second test was taken into account to eliminate learning effect. Glaucoma patients were chosen to cover a large range of deficits. Quantitative analysis of global indexes was performed as well as qualitative comparison of visual fields by a trained optometrist. RESULTS: Compared to Full Threshold, testing time was reduced by 51% in normals and 49% in glaucoma with SITA Standard and by 72% and 69% with SITA Fast, respectively. In glaucoma, mean testing time dropped from 16'01" with Full Threshold to 8'05" with SITA Standard and to 4'55" with SITA Fast. Quantitative comparison showed a high correlation between indexes (MD Full Threshold vs MD SITA Standard: r = 0.98, p < 0.01; PSD Full Threshold vs PSD SITA Standard: r = 0.94, p < 0.01). However SITA Standard and SITA Fast had a tendency to underestimate visual field defects. In glaucomatous subjects, mean MD ameliorated by 1.01 dB with SITA Standard and by 1.71 dB with SITA Fast. Mean PSD ameliorated by 0.04 dB and 0.43 dB, respectively. Qualitative analysis confirmed these last results showing artificial slight or important improvement of visual fields in 21% of the cases with SITA Standard and 30% with SITA Fast, compared to Full Threshold. CONCLUSION: SITA Standard and SITA Fast strategies improve dramatically visual field testing time, by 51% and 72% respectively. However, one should be cautious in comparing results obtained with different algorithms, as these new strategies improve the mean defect and, to a lesser extent, the localized defect.
The GLC1A locus for autosomal dominant juvenile and middle age onset primary open angle glaucoma (OAG) has been mapped to chromosome 1q21-q31. OAG, however, is a heterogeneous disease. We tested linkage of OAG and ocular hypertension (OHT), a major risk factor for OAG, to GLC1A in eight French families with multiple cases of juvenile and middle age onset OAG. There was strong evidence of genetic heterogeneity, four families being linked to GLC1A and two or three others being unlinked, depending on whether the complete OAG phenotype was analysed alone or jointly with OHT. Peak intraocular pressure (IOP) did not differ significantly between the two groups of families, while linkage to GLC1A conferred a highly increased risk of developing OAG and of having severe glaucomatous optic neuropathy. Testing linkage of familial OAG to GLC1A may therefore have prognostic value too.
PURPOSE: To evaluate the effects of transscleral cyclophotocoagulation with the diode laser for refractory glaucoma with respect to intra-ocular pressure, reduction of medical therapy and complications. METHODS: The diode laser system (Iris Medical Instrument, Oculight SLX) was used to treat 50 eyes of 47 patients with therapy resistant glaucoma and a poor prognosis with filtering surgery. All eyes had maximal hypotonic therapy and 40 (82%) patients were using carbonic anhydrase inhibitors. Laser energy was delivered to the eye through a quartz glass fiber optic probe [13 to 20 spots over 270 degrees using 3.5 J (1.75 W x 2.0 sec)]. The mean follow-up was 19.4 +/- 9.1 months (from 12 to 29 months). RESULTS: Intra-ocular pressure significantly decreased from mean baseline 32.4 +/- 9.1 mmHg to 19.7 +/- 8.1 mmHg at the end of the follow-up (p < 0.001). An intra-ocular-pressure below 20 mmHg was obtained in 66% of the eyes. In 13 patients the carbonic anhydrase inhibitors were discontinued. Six of the 8 painful eyes had pain relief. Visual acuity decreased in 17 (34%): cataract progression in 5 eyes, uncontrolled intra-ocular-pressure in 4 eyes, glaucoma progression despite controlled intra-ocular-pressure in 3 eyes, corneal dystrophy in 3 eyes. Chronic uveitis occurred in 5 (10%) eyes. No conjonctival, scleral or direct lens damage was detected. CONCLUSION: Contact transscleral cylophotocoagulation with the diode laser system can be successfully used to reduce intra-ocular-pressure in therapy resistant glaucoma. The incidence of complications is low with no loss of vision related to cyclodestruction.
PURPOSE: Ciliary photocoagulation was used to reduce pressure in eyes with refractory glaucoma or to suppress pain in blind painful eyes. The efficiency of transscleral cyclophotocoagulation (TSCPC) with a clinical diode laser system (Iris Medical Instrument, Oculight SLX) was evaluated. METHODS: This diode laser system (wavelengh: 810 nm) provides light energy to the eye through a specially designed quartz glass fiberoptic probe allowing precise location centered 1.2 mm behind the limbus, i.e. in front of the ciliary body. Thirty eight eyes in 38 patients with refractory glaucoma underwent TSCPC with the diode laser. RESULTS: Three months after surgery, intra-ocular pressure was controlled at 20 mmHg or below in 70% of the patients. Patients who most failed with the TSCPC had higher initial IOP (neovascular and congenital glaucoma). Seventy five percent of the painful glaucoma were painless after the laser treatment. Only a few cases (10%) of transient secondary hypertony were observed. The inflammatory response (21%) was mild and transient. No case of scleral perforation, no case of posterior uveitis, cararact or hypotony were observed. CONCLUSION: The transscleral ciliary photocoagulation laser diode system is efficient to reduce intraocular pressure in refractory glaucoma. Complications are mild compared with other methods of cyclophotocoagulation. A long-term study is necessary to evaluate the results on IOP and the incidence of hypotony.
In order to evaluate the optic nerve head perfusion in patients with primary open-angle glaucoma (POAG), we measured the velocity of the red blood cells (RBCs) in the capillaries of the optic nerve head with a laser-Doppler velocimeter and evaluated the blood viscosity by determining the capacity of the RBCs to disaggregate with an erythroaggregameter. Our results showed that in POAG patients optic nerve blood velocity was reduced and that the aggregability of the RBCs was increased. The two parameters were not significantly correlated, possibly because of local papillary autoregulation and anatomical variability in the papilla vessels. These two factors could explain why the same rheological anomaly in two subjects could lead to different responses in blood velocity. The RBC hyperaggregability cannot be explained by quantitative modifications of the plasma proteins. Modifications in the membrane of the RBCs could indeed be responsible for hyperaggregability, since our data suggest that deformability of the RBCs is impaired in glaucoma.
Optic disc blood flow velocity was measured in healthy patients, those with primary open angle glaucoma (POAG), and patients with normal pressure glaucoma (NPG). The velocity of the red blood cells (RBCs) in the capillaries of the optic nerve head (ONH) has been measured with a laser Doppler velocimeter (LDV), and blood viscosity has been evaluated notably by determining the aggregability of the RBCs with an erythroaggregameter. Our results in POAG patients and NPG patients showed that their optic nerve blood flow velocity was reduced and that the aggregability of the RBCs was increased. The hyperaggregability of the erythrocytes is responsible for the increase of the local viscosity in the papillary capillary network. These haemodynamic modifications observed in patients with glaucoma support the hypothesis of a vasogenic mechanism that could impair the optic nerve in glaucoma patients.
Three cases of ocular myasthenia gravis were observed. The first patient, a 74-year-old man was found to have complete left ophthalmoplegia and ptosis unchanged at examination on month after onset. The second patient, a 42-year-old man, developed incomplete right ophthalmoplegia with pseudoanterior internuclearis ophthalmoplegia, then ptosis two days later. The third patient, a 70-year-old man, presented with sudden onset complete right palsy of the third nerve. Diabetes mellitus or intra-cranial lesions were suspected in all three patients although laboratory tests, tomodensitometry, nuclear magnetic resonance imaging, or arteriography gave no confirmation. Ptosis was relieved and eye movement was improved after the intravenous edrophonium test, but electromyography was negative. The three patients were treated with anticholinesterase agents and showed unequivocal improvement. The second patient underwent thymectomy. Clinicians should inform patients of the contraindications of drugs in this disease. The diagnosis of pure oculomotor forms of myasthenia gravis is sometimes difficult to establish and should be suspected in cases of unexplained oculomotor palsy.
Leber's optic neuroretinitis is a particular form of optic neuropathy characterized by swelling of the optic disc and a stellate pattern of exsudative deposits in the macula. It occurs most often in healthy young subjects who have acute monolateral visual loss, often preceded by presumed viral illness. The etiology is unknown and viral infection has been suggested in the pathogenesis of this condition. The prognosis for visual recovery is reported to be excellent, but late visual sequelae have been described: loss of vision or visual field loss. This entity should be recognized and distinguished from more serious diseases causing septic neuroretinitis or papillitis.
The vascular participation to the optic nerve pathogenesis has been contradicted. The red blood cell velocity in the optic nerve capillary with a laser Doppler velocimeter, an atraumatic and reliable method, and the aggregability was determined with an erythroaggregameter to know whether an erythrocyte hyperaggregability could slow down the optic nerve blood flow as it has been previously demonstrated in an experimental study. The experiment on the open angle glaucoma patients showed that their optic nerve blood flow was reduced, and their erythrocyte aggregability significantly increased. The two parameters were not significantly correlated, certainly because of a local papillary autoregulation and of the papilla vessels variability, those two factors could modulate the blood flow response to blood qualitative changes. The erythrocyte hyperaggregability could be explained by erythrocyte membrane modifications that could agree with the glaucoma heredity.
We study capillary microcirculation on the optic nerve head and its interrelation with blood rheological modifications. The mean maximal velocity has been evaluated in the capillaries of the rabbit optic nerve with a laser doppler velocimeter, in physiological conditions and after intravenous Dextrane 250 injections. Dextrane 250 increases red blood cells aggregation and induces blood hyperviscosity at low flow rates. This hyperaggregation is determined with a reflectometric method. Experimental results show a significant reduction of blood velocity when blood viscosity increases. In our present study, we compare blood capillaries flow rate in the optic nerve, between two groups: healthy humans and subjects suffering from glaucoma. The aggregation level is simultaneously measured for the two groups. First results seem to prove that blood flow rate decrease is associated with red blood cells aggregation increase for the second group.