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Biomedical subjects

H Helbig

Publications and source records attributed to H Helbig.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Long-term vision follow-up after vitrectomy in diabetic retinopathy].

BACKGROUND: We investigated whether visual acuity remained stable in the long run after vitrectomy for complications of diabetic retinopathy and which risk factors for a decrease in vision could be identified. MATERIALS AND METHODS: The charts of 389 patients who had undergone vitreous surgery for complications of diabetic retinopathy between 1990 and 1994 were retrospectively reviewed. The median follow-up was 26 months with a minimum of 6 months. RESULTS: Seventy-two percent of the eyes with a vision of 20/200 or better within 6 months after surgery retained this vision after 2 years. The percentage of eyes with vision of less than 5/200 was 25% after 6 months and increased to 41% after 4 years. After 2 years 24% of the eyes had lost two or more lines compared to the best vision within the first 6 months after surgery. The main cause for a decrease of vision in type-I diabetics was retinal detachment, in type-II diabetics a progression of maculopathy and opticopathy. Risk factors for a detachment were pre-existing retinal detachment before surgery and reduced postoperative vision. The risk factor for a progression of maculopathy and opticopathy was a silicone tamponade. CONCLUSIONS: Eyes with good vision soon after surgery remain stable in the long run. Eyes with advanced stages of diabetic retinopathy and only ambulatory vision after surgery have an increased risk for new loss of visual function in the long run.

Adult↗
PubMed1996

Primary vitrectomy without scleral buckling for rhegmatogenous retinal detachment.

BACKGROUND: Pars planta vitrectomy has evolved as an alternative method in the treatment of more complicated rhegmatogenous retinal detachments. We report a series of patients who underwent primary vitrectomy with gas tamponade without the use of additional scleral buckling. METHODS: A retrospective study of 53 patients with a follow-up of 6-45 months (mean 17.8 months) was carried out. Preoperative findings included unusual, multiple or large breaks, vitreous haemorrhage, proliferative vitreoretinopathy and bullous retinal detachment. Preoperative visual acuity was between light perception and 1.0, with 30% (16/53) of patients with 0.4 or better. RESULTS: Retinal reattachment was achieved in 64% of cases (34/53) with one and in 92% (49/53) with one or more operations. Final visual acuity was between light perception and 1.0, with 41% (22/53) of patients with 0.4 or better. Cataract formation occurred in 86% (37/43) of all patients with a clear lens preoperatively. Macular pucker was noted in 11% (6/53) and postoperative proliferative vitreoretinopathy causing redetachment in 6% (3/53). CONCLUSION: With primary vitrectomy, a high final anatomical success rate with few intraoperative complications can be achieved in more complicated forms of rhegmatogenous retinal detachment. The major drawback of the procedure is the high incidence of post-operative cataract formation.

Adult↗
PubMed1996

[Limits and possibilities of vitreous body surgery in diabetic retinopathy].

BACKGROUND: Several indications for vitreous surgery for complications of diabetic retinopathy have been established, but there is little well-founded information concerning situations in which visual prognosis is poor and vitreous surgery should not be performed. MATERIALS AND METHODS: The charts of 389 patients who had undergone vitreous surgery for complications of diabetic retinopathy between 1990 and 1994 were retrospectively reviewed. The minimum follow-up was 6 months with a median of 26 months. Using multivariate logistic regression analysis we studied factors which were correlated with a postoperative visual acuity of less than 5/200. A model was developed predicting the probability of an unfavorable visual outcome in various situations. RESULTS: Forty-five eyes (12%) had a best postoperative visual acuity of less than 5/200. Risk factors were detachment of the macula, extent of the detachment, iris neovascularisations and the duration of visual loss. For reoperations similar risk factors were found. The chance that an eye with total tractional retinal detachment of more than 6 months duration and with rubeosis of the iris will achieve a postoperative visual acuity of 5/200 or better is only 2%. CONCLUSIONS: Eyes with total tractional retinal detachment, especially with longer duration of the detachment and rubeosis, have a very poor chance of achieving useful vision and should not be operated.

Adult↗
PubMed1996

[Phenocopies of hereditary retinal degenerations].

BACKGROUND: Phenocopies of retinal degenerations mimic the clinical signs of inherited retinal dystrophies. The purpose of this study is to discuss the difficulties of differential diagnosis. METHODS: Four patients were examined ophthalmologically and by standard electroretinography (ERG). RESULTS: (a) A 19-year-old woman presented with progressive visual loss, bone spicules, concentric narrowing of visual fields and extinguished ERG responses. At 3 years of age, she had developed a retinopathy induced by an infection with measles. (b) A 27-year-old man had bilateral visual loss, night blindness, pigmentary retinal changes, marked attenuation of visual fields and a reduced ERG. All signs of syphilitic retinopathy were regressive under antibiotic therapy. (c) A 59-year-old man showed a visual loss in the left eye, bilateral photophobia, color vision disturbances and a ring scotoma. Cone responses were nonrecordable in the ERG. A birdshot chorioretinopathy was suggested by ophthalmoscopic appearance and HLA typing. (d) A 40-year-old woman presented with paravenous pigmented retinochoroidal atrophy associated with Behcet disease. CONCLUSION: Systemic viral or bacterial inflammation as well as autoimmune disorders may present as phenocopies of hereditary retinal degenerations. A faulty diagnosis may have serious consequences, because necessary therapy may be withheld. Moreover, the misdiagnosis of a hereditary retinal degeneration may have severe effects on the psychic and social status of the patient.

Adult↗
PubMed1996

Life expectancy of diabetic patients undergoing vitreous surgery.

BACKGROUND: Patients with advanced diabetic eye disease are commonly in poor general health. In addition to the ocular status, life expectancy is an important factor in the decision whether and how to perform vitreous surgery. The present study investigates mortality and risk factors for survival in diabetic patients following vitrectomy. METHODS: The follow up of 332 consecutive patients who underwent vitrectomy for complications of diabetic retinopathy between 1990 and 1994 was studied retrospectively. Survival and risk factors for survival were analysed using the Kaplan-Meier life table method and for multivariate analysis the Cox proportional hazard model. RESULTS: The 5 year survival rate was 68%. Absence of heart disease was the most important predicting factor for survival. Fifty per cent of the patients with heart disease had died within 3.5 years. Patients without heart disease had a 5 year survival rate of 90%. Other significant, independent risk factors were age and presence of nephropathy. CONCLUSION: In diabetic patients undergoing vitrectomy the presence of heart disease indicates a poor prognosis for survival. This should be taken into consideration for indications and strategies in cases of vitrectomy.

Adult↗
PubMed1996

Management of hypotonous cyclodialysis with pars plana vitrectomy, gas tamponade, and cryotherapy.

BACKGROUND AND OBJECTIVE: Cyclodialysis after ocular trauma or surgery may lead to hypotony and visual loss. A new surgical approach for the treatment of cyclodialysis is reported. PATIENTS AND METHODS: In three patients with long-standing cyclodialysis and hypotony, a pars plana vitrectomy with gas tamponade and transscleral cryotherapy to the region of the cleft was performed. RESULTS: In all patients intraocular pressure increased to normal or near normal, choroidal detachment and retinal and disc edema resolved, and visual acuity increased. CONCLUSION: A hypotonous cyclodialysis can be successfully treated with vitrectomy, gas tamponade, and cryotherapy. This approach may be superior to other techniques if there are also additional posterior segment problems, or if there is lens dislocation.

Adult↗
PubMed1996

Cataract surgery and YAG-laser capsulotomy following vitrectomy for diabetic retinopathy.

The present study was initiated to assess time-course and risk factors for the development of cataract and posterior-capsule opacification as well as complications of cataract surgery and YAG-laser capsulotomy following vitrectomy for diabetic retinopathy. The charts of all patients undergoing vitrectomy for diabetic retinopathy during a 5-year period in a university eye hospital were retrospectively reviewed. The course of 306 consecutive eyes in which the lens was retained during vitrectomy was analyzed for subsequent cataract surgery and YAG-laser capsulotomy. The first 6 months after cataract or YAG-laser surgery were examined for the occurrence of complications. Data were analyzed with regard to the time course using Kaplan-Meier life-table analysis. The proportion of eyes that underwent cataract surgery after vitrectomy increased nearly linearly with time, approaching 75% after 5 years. Silicone tamponade (relative risk 1.9; P = 0.0005) and transscleral retinal cryotherapy (relative risk 1.4; P = 0.003) were risk factors for subsequent cataract surgery. No significant cataractogenous effect of intravitreal gas as compared with balanced salt solution was found. YAG-laser capsulotomy was performed in 60% of vitrectomized diabetic eyes within 2 years but in only 10% of nondiabetic controls (P < 0.0001). Within 6 months of extracapsular cataract surgery with implantation of an intraocular lens (IOL) in 54 eyes, no serious complication was observed. After YAG-laser capsulotomy, vitreous hemorrhage occurred within 6 months in 6 of 21 eyes. In conclusion, cataract surgery was performed in 75% of the phakic eyes within 5 years of vitrectomy for diabetic retinopathy. Posterior capsular opacification is particularly common in this subset of eyes. No serious complication was observed after extracapsular cataract surgery with IOL implantation, but YAG-laser capsulotomy was associated with an increased risk for vitreous hemorrhage.

Adult↗
PubMed1995

[Oxygen in the anterior chamber before and after cataract operation].

The purpose of the study was to investigate whether removal of the lens would change the physiology of oxygen supply to the anterior segment of the eye. Oxygen partial pressure in the anterior chamber was measured using oxygen-sensitive electrodes during cataract surgery or removal of after-cataracts in aphacic and pseudophacic eyes. We found significantly reduced oxygen tension in the anterior chamber of aphacic or pseudophacic eyes compared to cataractous eyes. These results could be explained either by a reduced barrier between aqueous humor and vitreous or by atrophic changes of the iris vasculature after cataract surgery. These changes in oxygen supply to the anterior chamber after cataract surgery could be clinically relevant in the eyes with ischemic diseases.

Aged↗
PubMed1995

Natural course of retinal development in preterm infants without threshold retinopathy.

In a consecutive series, 209 preterm infants with birth weights below 1501 g or a gestational age of < or = 32 weeks were observed. Stage 3 retinopathy of prematurity (ROP) developed in 48 infants (23%) of between 32 and 46 weeks postconceptional age (PCA; mean, 37 weeks). Stage 3 ROP was not seen before 6 weeks after birth. Threshold ROP was seen and treated at between 34 and 42 weeks PCA (mean, 38 weeks PCA; n = 22, 10.5%). A subgroup of 126 untreated infants were followed until complete retinal vascularisation. At estimated term, 38.7% of eyes with vessels ending in zone 3 at the first examination showed complete vascularisation as compared with 17.6% of eyes with vessels ending in peripheral zone 2 and none of those with vessels ending in central zone 2. Occurrence of ROP delayed retinal development. At estimated term, no eye with any stage of ROP showed complete vascularisation as compared with 35.4% of eyes without ROP. Regression of stage 3 ROP below threshold started in all cases before 56 weeks PCA.

Cryosurgery↗
PubMed1995

[Evaluation of published recommendations for screening studies of retinopathy of prematurity].

PURPOSE: Evaluation of different and partially contradictory guidelines for screening for retinopathy of prematurity published in Germany. PATIENTS: The data on 1219 preterm infants examined in Bern (n = 900) and Berlin (n = 319) were analyzed. A total of 680 preterm infants (56%) had a birth weight below 1500 g. The remaining infants were examined because oxygen had to be supplied or surgery done before or around the estimated delivery time. RESULTS: Stage 3 retinopathy was found in 88/1219 (7.2%) preterm infants. Only 5/88 infants weighed more than 1500 g at birth. Three of these infants had a birth weight below 2000 g and needed supplemental oxygen for a prolonged period of time. The other 2 infants had birth weights of more than 2000 g and were severely ill. Of 1219 preterm infants, 37 (3%) developed threshold retinopathy (according to the criteria of the multicenter trial); 35/37 infants weighed less than 1230 g at birth. The remaining 2 children (1650 g and 2185 g birth weight) were severely ill. CONCLUSIONS: Preterm infants should be screened for retinopathy of prematurity: (1) if the birth weight is below 1500 g; (2) if the birth weight is below 2000 g and oxygen supply was necessary for more than 30 days; (3) if infants are very sick or must undergo multiple surgery before term. The first examination should be scheduled for the 6th week postnatal and not before 31 weeks postmenstrual age.

Berlin↗
PubMed1994

Sympathetic ophthalmia following laser cyclocoagulation.

We describe a 49-year-old white man with sympathetic ophthalmia following contact neodymium-YAG laser cyclotherapy. There was no invasive surgery, and no perforating injuries preceded cyclodestructive therapy. The eye had hemorrhagic secondary glaucoma due to Coats' disease. It was treated three times with contact cyclophotocoagulation after cyclocryotherapy failed to lower intraocular pressure. Subsequently, the intraocular pressure slowly decreased and the eye became phthisical 15 months after the last surgery. Intraocular inflammation developed in the fellow eye and sympathetic ophthalmia was suspected. Histologic and immunohistologic study of the enucleated blind eye confirmed this diagnosis.

Ciliary Body↗
PubMed1994

[Varicella zoster virus infections of the retina in patients with and without immune suppression].

BACKGROUND: Infections of the retina with the varicella-zoster virus can lead to severe visual impairment. Patients with immunodeficiency are particularly predisposed to viral infections, and the alterations of the immune system may lead to a modified clinical picture. PATIENTS: Two cases of infections of the retina with the varicella-zoster virus in an immunocompromised and an immunocompetent patient are presented. The first otherwise healthy patient showed the typical clinical picture of the "acute retinal necrosis syndrome" with orbital pain and decrease of vision. He had inflammatory infiltration of the vitreous and the anterior chamber, retinal vasculitis, optic disc edema and whitening of the peripheral retina with full thickness retinal necrosis. The second patient with AIDS presented with a history of sudden painless loss of vision in one eye. He had a swollen optic disc, inflammatory infiltrates in the choroid and virtually no cellular infiltration of the vitreous or the anterior chamber. The diagnosis of varicella-zoster virus infection of the retina was confirmed in both patients by polymerase chain-reaction of aqueous and vitreous humor, by determination of intraocular antibody titers and immunohistochemistry on retinal biopsy material, respectively. In both patients no inflammation in the fellow eye developed under therapy with aciclovir. The first patient regained full vision after vitrectomy with membrane dissection. CONCLUSIONS: Varicella-zoster virus infections of the retina can present with different clinical pictures in immunocompromised and immunocompetent patients. Early diagnosis and adequate medical and surgical therapy can significantly improve visual prognosis.

AIDS-Related Opportunistic Infections↗
PubMed1994

Anterior-chamber hypoxia and iris vasculopathy in pseudoexfoliation syndrome.

Iris vasculopathy is a well-recognized clinical feature in pseudoexfoliation syndrome (PES). In the present study we examined the morphology of the iris vasculature in PES using electron microscopy and we tested whether these iris vascular changes were correlated with an impaired oxygen supply to the anterior chamber. In the affected vessels we found a gradual degeneration of vascular cells, progressing from adventitial to endothelial cells, associated with the production of excess extracellular material, including pseudoexfoliative fibers. Oxygen partial pressure (pO2) was measured in the anterior chamber during cataract surgery using a polarographic oxygen electrode in eyes with and without PES. The pO2 value measured in the anterior chamber of 10 eyes without PES was 45 +/- 11 mmHg (mean +/- SD) in the chamber angle, 33 +/- 12 mmHg in front of the pupillary margin, and 13 +/- 8 mmHg in the center of the pupil. This spatial distribution of pO2 indicates that aqueous humor oxygenation occurs along the anterior iris surface. The mean pO2 values obtained in 8 patients with PES were 19 +/- 6 mmHg in the chamber angle, 16 +/- 4 mmHg in front of the pupillary margin, and 8 +/- 3 mmHg in the center of the pupil. We conclude that anterior-chamber hypoxia due to iris vasculopathy may represent a complication of PES that could play a role in the pathogenesis of PES-associated alterations in the anterior segment of the eye.

Aged↗
PubMed1993

Effect of elevated glucose concentration on membrane voltage regulation in retinal capillary pericytes.

The influence of elevated glucose concentration on resting membrane voltage, electrogenic Na(+)-K(+)-ATPase, and ATP-sensitive potassium channels (KATP channels) was studied in cultured bovine retinal capillary pericytes using conventional microelectrodes. The resting membrane voltage in cells grown in medium containing 5 mM glucose (control) averaged -27 +/- 1.2 mV (mean +/- SE, n = 26) and was not different from cells grown in medium containing 22.5 mM glucose (-26 1.2 mV, n = 26). Addition of ouabain (10(-4) M), a specific inhibitor of the Na(+)-K(+)-ATPase, depolarized the membrane potential by 3.6 +/- 0.4 mV (n = 10) in cells grown under control conditions and 0.7 +/- 0.2 mV (n = 6) in cells grown under elevated glucose conditions. Thus, electrogenic activity of the Na(+)-K(+)-ATPase was significantly (P < 0.0001) reduced to 19% compared with control conditions. Electrogenic Na(+)-K(+)-ATPase activity could be partially restored (ouabain-induced depolarization delta V = 2.0 +/- 0.2 mV, n = 6) in cells grown with high glucose in the presence of the aldose reductase inhibitor tolrestat (10(-5) M). The potassium channel opener Hoe 234 (10(-6) M) induced membrane potential hyperpolarization in control cells (delta V = 7.3 +/- 1.2 mV, n = 13), which could be completely inhibited by the KATP channel blocker glibenclamide (10(-7) M, n = 5). This indicates that pericytes possess KATP channels. The effect of KATP channels on membrane voltage was not significantly changed (P = 0.16) in cells cultured under high-glucose conditions (delta V = 9.6 +/- 2.0 mV, n = 6).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Insulin-induced hyperpolarization in retinal capillary pericytes.

PURPOSE: This study investigated the mechanism of insulin-induced membrane voltage hyperpolarization in retinal capillary pericytes, which possess electrical membrane properties typical for smooth muscle cells and are supposed to regulate retinal microcirculation by a contractile mechanism. METHODS: The mechanism of insulin-induced hyperpolarization was studied in cultured bovine retinal capillary pericytes using conventional microelectrodes. RESULTS: Resting voltage averaged -28 +/- 0.9 mV (mean +/- SEM, n = 45). Insulin (10(-9) to 10(-7) mol/l) induced a slow hyperpolarization in a dose-dependent fashion. Voltage change (delta V) was -3.1 +/- 0.4 mV (n = 14, P < 0.0001, = control) with an insulin concentration of 10(-8) mol/l. Blockade of potassium channels with Ba2+ (5 mmol/l) completely abolished the hyperpolarizing effect of insulin (n = 5). Apamin (10(-9) mol/l), a blocker of low-conductance Ca(2+)-activated potassium channels, also completely inhibited the insulin-induced hyperpolarization (n = 4). Blocking ATP-sensitive potassium channels with glibenclamide (10(-7) mol/l) did not reduce the hyperpolarizing action of insulin (delta V = -2.2 +/- 0.4 mV, n = 5, P = 0.29). Equivalent hyperpolarizations were recorded when insulin was added in the presence of ouabain (10(-4) mol/l) to inhibit the electrogenic Na+/-/K+/-ATPase (delta V = -3.5 +/- 1.0 mV, n = 4, P = 0.68). When pericytes were grown for 3 days in culture medium with elevated glucose concentrations (22.5 mmol/l), the resting membrane voltage and the insulin-induced hyperpolarization were not significantly altered. CONCLUSION: Insulin hyperpolarizes the membrane voltage of retinal pericytes probably mediated by activation of apamin-sensitive Ca(2+)-activated potassium channels. Therefore, hormonal modulation of membrane voltage by insulin might be an important factor in the regulation of pericyte contractility and retinal microcirculation under physiological conditions and in diabetes mellitus.

Adenosine Triphosphate↗
PubMed1993

Oxygen in the anterior chamber of the human eye.

Oxygen partial pressure (pO2) was measured in the anterior chamber of the human eye during routine cataract surgery using a polarographic oxygen electrode. We found a reproducible spatial distribution of oxygen in the aqueous humor. The pO2 (n = 8) was 44.9 +/- 9.1 mmHg in the chamber angle, 35.0 +/- 10.9 mmHg above the pupillary margin, and 13.5 +/- 8.0 mmHg in front of the center of the pupil. Pretreatment of the eye with the alpha-adrenergic agonist phenylephrine (5%) resulted in a marked reduction in pO2 to 19.8 +/- 5.8 mmHg in the chamber angle, 13.4 +/- 4.7 mmHg above the pupillary margin, and 7.4 +/- 3.3 mmHg in front of the center of the pupil (n = 8). The pO2 in the anterior lens was very low (2.5 +/- 0.6 mmHg, n = 7). We conclude that oxygen is supplied at the anterior iris surface to the aqueous humor. The lens is an extremely low oxygen compartment. Topical phenylephrine causes anterior-segment hypoxia, probably by the constriction of iris vessels.

Aged↗
PubMed1992

Membrane potentials in retinal capillary pericytes: excitability and effect of vasoactive substances.

Retinal capillary pericytes are believed to have a contractile function and to regulate retinal blood flow at the microvascular level. Membrane potential is an important control element for contractility in smooth muscle cells. In the present study, bovine retinal capillary pericytes have been grown in tissue culture and membrane potentials have been measured using glass microelectrodes. Resting potentials averaged -31 +/- 7 mV (n = 203). Relative K+ conductance was low, with a transference number for K+ of 0.16. Readdition of K+ to K(+)-depleted cells transiently hyperpolarized the membrane potential, probably by stimulating the electrogenic Na+/K+ transport. Repetitive spike-like depolarizations (action potentials) were induced by stimulating the Na+/K(+)-ATPase, by applying norepinephrine (10(-5) mol/l), and by adding 10 mmol/l Ba2+. These action potentials depended on the presence of extracellular Ca2+ and were inhibited by the Ca2+ antagonist nifedipine (10(-6) mol/l). Norepinephrine (10(-5) mol/l) depolarized the membrane by 7.4 +/- 3.5 mV (mean +/- SD, n = 49). This response was blocked by the alpha 1-antagonist prazosin (10(-5) mol/l). Histamine also led to a membrane depolarization of 8.6 +/- 2.8 mV (n = 49), which could be inhibited by the H1-antagonist diphenhydramine. Endothelin (10(-7) mol/l), vasopressin (10(-6) mol/l), and acetylcholine (10(-4) mol/l) had no major effects on membrane potential. The conclusion is that retinal capillary pericytes are excitable cells and react to several vasoactive substances.

Acetylcholine↗