[Femtosecond laser ablation and scanning microscopy of the internal retinal limiting membrane: an experimental study].

The investigation was undertaken to study whether femtosecond laser ablation and microscopy might be used in the internal retinal borderline membrane. Ablation of internal limiting membrane preparations removed using or not using indocyanine green was made by a low-energy femtosecond laser. Examination of the preparations by laser and electron microscopy revealed precision laser cuts of the internal retinal borderline membrane. The use of indocyanine green during laser ablation reduced laser irradiation parameters as compared to the dye not being applied. Low-energy femtosecond lasers enable precision contactless ablation of the internal borderline membrane to be carried out without collateral damage to the adjacent tissue. The parameters of laser impulses, particularly low ones used in the ablation of indocyanine green-stained preparations, prove the photosensitizing effect of the dye.

[Does acetylsalicylic acid have a negative influence on photodynamic therapy?]. / Wirkt sich Acetylsalicylsäure negativ auf die photodynamische Therapie aus?

BACKGROUND: Non-thermal photodynamic therapy (PDT) is presently being used for the treatment of certain forms of age-related macular degeneration (AMD). This therapy results in selective occlusion of newly growing vessels. Due to this effectiveness of PDT the question came up whether inhibitors of platelet aggregation have an influence on PDT. PATIENTS AND METHODS: Our retrospective study included 60 patients with mainly classic subfoveal choroidal neovascularizations (CNV) due to AMD. All patients were treated by PDT. Thirty patients took acetylsalicylic acid (aspirin) because of their general disease before and during treatment. In the control group none of the patients took acetylsalicylic acid. RESULTS: Best corrected visual acuity and measured dimension of the choroidal neovascularization showed before beginning PDT no statistically significant difference (visual acuity p=0.676; dimension of CNV p=0.678). Also no significant difference existed between visual acuity (p=0.412; p=0.226; p=0.969) and CNV (p=0.871; p=0.245; p=0.323) at the follow-up examination. CONCLUSION: Our study has shown that acetylsalicylic acid does not have any effect on PDT treatment.

[The Ahmed glaucoma valve. Medium term results]. / Die "Ahmed glaucoma valve" Mittelfristige Ergebnisse.

BACKGROUND: In complicated glaucoma, when classical filtrating surgery would be ineffective, aqueous shunts may be used. Complications due to hypotonia are reduced by valved systems, such as the Ahmed glaucoma valve (AGV). METHOD: In a retrospective case control study, 28 patients with complicated glaucoma were included. In addition to the clinical examination, we examined the size and function of the filtering area using ultrasound. RESULTS: The medium term follow-up was 25+/-16 months, the preoperative intraocular pressure (IOP) 35.5 mmHg+/-10.3 while 17 eyes were pseudophakic and nine aphakic. In the first weeks after AGV implantation, the mean IOP was 6.3+/-2.5 mmHg. In nine eyes, the pressure was less than 5 mmHg and five developed a temporary choroidal detachment. At the last visit, IOP was regulated in 22 eyes (82.1%). There was no correlation between IOP regulation and the size of the filtering bleb or the increase in the latter by digital pressure. CONCLUSION: In the management of complicated glaucoma, if there is a high risk of failure due to conjunctival scarring, AGV implantation can be used as a save procedure with a success rate comparable to other glaucoma implants.

Ablation of vitreous tissue with erbium:YAG laser.

PURPOSE: Using a noncontact erbium (Er):yttrium--aluminium--garnet (YAG) laser, ablation of vitreous was compared to distilled water in vitro. METHODS: The porcine vitreous body and distilled water were ablated in vitro at different pulse lengths and pulse energies. Selected pulse energies were 25, 35, 45, 75, and 100 mJ (pulse rate: 1 Hz; laser beam diameter at the surface of the sample: 2 mm). Pulse lengths were at 140 +/- 3 microsec, 190 +/- 4 microsec, and 240 +/- 5 microsec. The loss of weight in vitreous tissue and distilled water was measured using precision scales and corrected for evaporation, respectively. The Mann-Whitney U test was used to assess the significance of differences in ablation rates of water and vitreous. P < 0.05 was considered statistically significant. RESULTS: Reproducible and constant ablation rates were found in both vitreous and distilled water in each of 10 consecutive series of 50 laser pulses at constant laser parameters. Ablation rates per pulse (microg/microsec) of vitreous tissue were as follows: 3.0 microg to 45.8 microg (140 microsec), 10.4 microg to 53.8 microg (190 microsec), and 17.9 microg to 24.2 microg (240 microsec). The ablation rates exhibited a linear correlation with increasing pulse energies and also with decreasing pulse lengths. Considering the pulse lengths of 190 microsec and 240 microsec with all pulse energies tested, the ablation rates of distilled water were significantly higher (P < 0.05) than ablation of vitreous tissue. The ablation rates at a pulse length of 140 microsec were not significantly different. The differences per pulse were as follows: 0.5 microg to 2.1 microg (140 microsec), 1.9 microg to 6.0 microg (190 microsec), and 3.5 microg to 8.7 microg (240 microsec). CONCLUSIONS: Vitreous ablation is possible using Er:YAG laser. The ablation characteristics of vitreous have proved to be similar but not equal to that of water.

Surgical removal of pontomesencephalic cavernous hemangiomas.

Cavernous hemangiomas of the brain stem are usually discovered accidentally during evacuation of a hematoma, and successful surgical treatment of these lesions is seldom achieved. With the increasing use of magnetic resonance imaging, the presence of a cavernous hemangioma can be detected before surgery, allowing an elective surgical approach. We successfully removed pontomesencephalic cavernous hemangiomas from 2 patients and pontomedullary hemangiomas from 2 others. Elective surgery was performed with perioperative bimodal monitoring of somatosensory and auditory evoked potentials. Performing surgery soon after the hemorrhage minimizes the risk of additional postoperative neurological deficit, since surgical excision is facilitated when the hematoma is not completely organized. Pontine hemangiomas are approached via the 4th ventricle. Mesencephalic hemangiomas are removed by a midline supracerebellar approach when they are lateralized by using a subtemporal approach. The lesion can be removed through a small incision in the brain stem at the site of the lesion. The favorable results, which include marked improvement of preoperative neurological deficits and documentation of complete removal of the lesion by magnetic resonance imaging, support a more aggressive approach to the treatment of symptomatic cavernous hemangiomas of the brain stem. Further investigation of the natural history of these lesions is mandatory.

Oral premedication with low dose midazolam modifies the immunological stress reaction after the setting of retrobulbar anaesthesia.

BACKGROUND/AIMS: An acute immunological stress reaction was previously reported to occur after the painful setting of retrobulbar anaesthesia before intraocular surgery. This study was conducted to find out whether an oral low dose premedication with midazolam would modify the immunological stress reaction. METHODS: 32 patients undergoing intraocular surgery using retrobulbar anaesthesia were included in a randomised, double blind trial. They received premedication with either 3.75 mg midazolam or placebo 30 minutes before the retrobulbar injection. Counts of leucocyte subpopulations, cardiovascular, and psychometric parameters were measured repetitively before and after the retrobulbar injection. RESULTS: The numbers of leucocytes increased significantly in the placebo group after the setting of retrobulbar anaesthesia (before retrobulbar injection: 6687 (SD 1025) cells x10(6)/l; after injection: 7067 (1022) cells x10(6)/l, p=0.0009) caused by rising numbers of neutrophils (before injection: 4111 (1063) cells x10(6)/l; after injection: 4352 (1147) cells x10(6)/l, p=0.0007) and natural killer cells (before injection: 290 (84) cell x10(6)/l; after injection 354 (133) cells x10(6)/l, p=0.003). There was no significant increase in total leucocytes (before injection: 5997 (1288) cells x10(6)/l; after injection: 6189 (1215) cells x10(6)/l) or in any leucocyte subpopulation in the midazolam group. A significant rise in systolic blood pressure occurred in the placebo group, but not in the midazolam group. CONCLUSION: A low dose premedication with midazolam attenuates the immunological and cardiovascular stress reactions occurring with retrobulbar anaesthesia.

Bacterial anterior chamber contamination with foldable silicone lens implantation using a forceps and an injector.

PURPOSE: To compare the rate of anterior chamber (AC) contamination during implantation of a foldable three-piece silicone lens using a forceps and an injector. SETTING: Department of Ophthalmology, University of Saarland, Homburg (Saar), Germany. METHODS: In a prospective, randomized study, we cultured AC aspirates of patients who had phacoemulsification with silicone lens implantation through a 3.5 mm temporal clear corneal incision. In Group A, the lens was implanted with a forceps and in Group B, with an injector. Immediately after lens implantation, the AC aspirate (0.05 to 0.10 ml) was collected and sent to the microbiology department. All cultures were incubated for 3 days. As a topical antibiotic, gentamicin was given preoperatively and intraoperatively. RESULTS: One hundred patients (50 in each group) were examined. In each group the bacterial contamination of the AC was 2%. CONCLUSION: Bacterial contamination of the AC was not significantly different after silicone lens implantation with a forceps and with an injector.

Possibilities and limitations of current stereo-endoscopy.

BACKGROUND: Stereo-endoscopy has become a commonly used technology. In many comparative studies striking advantages of stereo-endoscopy over two-dimensional presentation could not be proven. To show the potential and fields for further improvement of this technology is the aim of this article. METHOD: The physiological basis of three-dimensional vision limitations of current stereo-endoscopes is discussed and fields for further research are indicated. New developments in spatial picture acquisition and spatial picture presentation are discussed. RESULTS: Current limitations of stereo-endoscopy that prevent a better ranking in comparative studies with two-dimensional presentation are mainly based on insufficient picture acquisition. CONCLUSION: Devices for three-dimensional picture presentation are at a more advanced developmental stage than devices for three-dimensional picture acquisition. Further research should emphasize the development of new devices for three-dimensional picture acquisition.

Ophthalmological aspects in patients with Werner's syndrome.

In ten of 18 eyes from nine patients with Werner's syndrome, cataract surgery was complicated by wound dehiscence and its consequences: peripheral anterior synechiae (4), secondary epiretinal gliosis (4), cystoid macular edema (3) in the framework of Hruby-Irvine-Gass syndrome, unplanned filtering bleb (2), and post-operative anterior ischemic optic neuropathy (1). Additionally, corneal endothelial decompensation occurred in eight eyes. In view of the fibroblasts' reduced growth potential, we suggest small surgical incisions, extracapsular cataract surgery using phacoemulsification, intraocular irrigation solutions protecting corneal endothelium, nonabsorbable single knot sutures not removed before 1 year after surgery, and no local or systemic use of cortisone.

Plasma lipids and composition of red cells in four cases of Werner's syndrome.

Four cases of accelerated aging, known as Werner's syndrome (WS), are presented. Plasma lipid and lipoprotein findings and lipid compositions of red cell membranes are compared to those of old and young healthy people. Typical clinical findings, as reported in the literature, confirmed the diagnosis. Furthermore, an elevated osmotic fragility of red blood cells (RBC) was observed. RBC membranes of WS patients showed phospholipid concentrations similar to those found in people aged over 70 years, which have been reported to be lower than those of mature donors aged below 30 years. Fatty acid patterns of RBC membranes and plasma phospholipids were indicative of some disturbance in phospholipid subclass distributions in WS-patients.

Oral low-dose midazolam as premedication for intraocular surgery in retrobulbar anesthesia: cardiovascular effects and relief of perioperative anxiety.

The aim was to investigate the efficacy and practicability of oral low-dose premedication with 3.75 mg midazolam (1/2 tablet Dormicum 7.5 mg) for selective intraocular surgery with retrobulbar anesthesia. Forty-six ASA II-III patients were randomly assigned to either group I: midazolam (n = 24) or group II: placebo (n = 22). Sedation was objectively quantified with a scale derived from the Glasgow-Coma-Scale and a verbal self-rating scale. Trait-anxiety was studied with the State-Trait Inventory by Spielberger, perioperative situative anxiety with the Erlanger Anxiety Scale. Cardiovascular variables and oxygenation were automatically monitored. Midazolam produced significant and sufficient sedation and significant anxiolysis. Systolic, diastolic and mean blood pressure were moderately but significantly, reduced. The effect on diastolic pressure was more pronounced. There was no effect on heart-rate. Oxygenation at all times remained well above 90% SpO2. In conclusion low-dose oral midazolam proved to be a single and effective premedication before intraocular surgery under local anesthesia.

The endocrine stress response after oral premedication with low-dose midazolam for intraocular surgery in retrobulbar anaesthesia.

PURPOSE: It was the purpose of this study to examine the endocrine stess response in patients undergoing elective intraocular surgery in retrobulbar anaesthesia (RBA), and the effect of an oral premedication with 3.75 mg midazolam on this reaction. METHODS: In a prospective double-blind study, 23 patients were randomly assigned to either group I (n = 12), receiving 3.75 mg midazolam, or group II (n = 11), receiving a matched placebo 60 min before RBA. Plasma concentrations of known mediators of the endocrinological stress response were analysed at five perioperative times: adrenocorticotropic hormone (ACTH), cortisole (CORT), somatotropic hormone (STH), epinephrine (EPI), norepinephrine (NOR), and dopamine (DOP). RESULTS: The observed endocrinological reaction was moderate. Perioperative anxiety and, above all, RBA were the main stressors. The endocrine stress response could best be seen within the fast-reacting sympathoadrenergic system. Midazolam significantly suppressed the epinephrine and the cortisole answer (p < 0.01). After RBA an ACTH plasma peak only was observed after placebo. Plasma-STH showed extreme variability. An STH-peak after midazolam is presumably due to a gonadotropic hormone-releasing hormone (GHRH) secretion directly stimulated by midazolam. Midazolam had no significant effect upon norepinephrine. A significant (p < 0.01) increase for plasma-cortisole was seen 60 min after the operation when compared to preoperative values. CONCLUSIONS: The results indicate that even at a low dose midazolam positively influences the endocrine stress response. The combination of this stress-reducing effect with the well-known hemodynamic stability, the distinct anxiolytic and sedative action, suggest low-dose midazolam as a favourable premedication for intraocular surgery.

Comparison of analgesia and akinesia after retrobulbar injections at different speeds.

PURPOSE: To assess how the speed of injection of local anesthetic solutions affected pain of injection, bulbar akinesia and analgesia with retrobulbar anesthesia (RBA). METHODS: 70 patients undergoing RBA for cataract surgery were enrolled in a prospective masked trial. They were allocated randomly to receive 5 ml anesthetic solution injected either within 20 seconds (group A) or within 60 seconds (group B). Additionally, akinesia of the orbicularis muscle was created according to O'Brien's technique. The pain of injection was registered on an ordinal analogue scale immediately before and after RBA. The following data were collected before and 20 minutes after retrobulbar injection: eye motility (Kestenbaum test), and corneal sensitivity (0: no sensitivity; 1: sensitivity remaining). Data were also collected on age, sex, and bulbar length, and any side effects of the intervention. RESULTS: Injection pain did not differ in the two groups. After RBA horizontal and vertical eye motility was slightly lower in group A than group B. Persistent motility was found in 18 patients in group A and 16 in group B. Median horizontal and vertical motility was 0 mm in both groups. Four patients in group A and five in group B had corneal sensitivity persisting after RBA. CONCLUSIONS: This comparison of different injection velocities brought to light no significant differences regarding bulbar analgesia and akinesia after RBA.

Risk factors for anatomical success and visual outcome in patients undergoing silicone oil removal.

PURPOSE: To define risk factors for anatomical success and visual outcome in patients undergoing removal of silicone oil. METHODS: This retrospective study included patients who had silicone oil removed at this hospital between 1996 and 2000. All were followed for at least six months. Patients with recurrent retinal detachment after silicone oil removal were compared with patients without this complication. We also compared patients whose vision improved or stabilized with patients whose vision deteriorated. Risk factors for anatomical success and visual outcome were identified. RESULTS: We analysed 94 eyes of 92 patients with silicone oil removal. Nineteen eyes (20%) had recurrent retinal detachment, and in 30 eyes (32%), the vision deteriorated after removal of the oil. Initial vision less than ambulatory vision, initial pathology of giant retinal tears and recurrent retinal detachment, postoperative hypotony and postoperative epiretinal membrane occurred more frequently in eyes with than without recurrent retinal detachment. Pre- and postoperative hypotony, postoperative epiretinal membranes and postoperative recurrent retinal detachment were also more frequent in eyes with deteriorated vision. CONCLUSIONS: When treating giant retinal tears or recurrent retinal detachments with silicone oil tamponade, surgeons and their patients need to be aware of the higher possibility of unfavorable results, particularly when the initial vision is less than ambulatory vision. The presence of risk factors before and after silicone oil removal should remind surgeons of the higher risk profile of this particular surgery.

Low-dose oral clonidine as premedication before intraocular surgery in retrobulbar anesthesia.

PURPOSE: We investigated whether low-dosed oral clonidine premedication before elective intraocular surgery in retrobulbar anesthesia is effective in terms of anxiolysis, sedation, stable hemodynamics, lower intraocular pressure and perioperative endocrine stress response. METHODS: In a prospective, randomised, double-blind study, 44 patients scheduled for elective intraocular surgery received either 0.15 mg clonidine (n=22) or a matched placebo (n=22) orally 60 minutes before retrobulbar anesthesia. The main study parameters were sedation, anxiolysis, hemodynamics and intraocular pressure. Additionally, mediators of endocrine stress responses were measured five times, in 13 patients after clonidine and 12 after placebo. RESULTS: After clonidine 86% of the patients showed sedation and after placebo 90.9% showed no sedation (p<0.01). Clonidine produced effective anxiolysis (Erlanger-Anxiety-Scale: 31.6 +/- 2.6 points vs. 38.1 +/- 8.5 points) before the operation (p<0.01). Systolic blood pressure was significantly lower after clonidine. Effects on mean and diastolic blood pressure were small but statistically significant. Norepinephrine and cortisol plasma concentrations were significantly lower after clonidine. Intraocular pressure was significantly lower too (p<0.05). No clinically relevant adverse effects were observed e.g. inappropriate sedation, hypotension (<100 mmHg), bradycardia (<50 bpm) or hypoxemia (SpO2<90%). CONCLUSIONS: Oral low-dose clonidine produces light sedation, significant anxiolysis and stable hemodynamics, and attenuates the endocrine response to perioperative stress. Thus, clonidine seems sufficient to increase patient comfort for intraocular surgery and might even offer clinically worthwhile benefits such as stable hemodynamics and a reduced response to perioperative stress.

[The Ahmed glaucoma valve - a new implant for high intraocular pressure]. / Die Ahmed Glaucoma Valve.Ein neues Implantat zur operativen Drucksenkung.

UNLABELLED: In incurable glaucoma the implantation of traditional drainage systems (such as the Molteno implant) usually leads to extreme hypotension in the eye in the first postoperative period. The Ahmed Glaucoma Valve presents an alternative method to avoid this problem. PATIENTS AND METHOD: Ten patients with incurable glaucoma received an Ahmed Glaucoma Valve. The average age was 59 years (22-81) and the follow-up period was an average of 8 months (4-20). RESULTS: In the early postoperative period the average IOP was 5.5 mm Hg (range 4-8.5). We saw chorioidal detachments in two patients but no shallow anterior chamber. In six patients the pressure rose over 22 mm Hg, but we induced filtration by massaging the eye or rinsing the system in three and two patients, respectively. In nine of the ten patients, tension was definitively regulated, in one with an additional topical medication against glaucoma. CONCLUSIONS: Unlike the classic glaucoma drainage systems, the Ahmed Glaucoma Valve reduces intraocular pressure in the first postoperative period without the problems of excessive hypotension.

[Dry eye. An update on epidemiology, diagnosis, therapy and new concepts]. / Das trockene Auge. Ein Update über Epidemiologie, Diagnose, Therapie und neue Konzepte.

Recent epidemiologic studies quote a prevalence of 5,2% to 63% for dry eye depending on definition. Many risk factors have been identified, among other things the female gender. Dry eye interferes significantly with quality of live. Measurement of the change in temperature and humidity during blinking turned out to be a reliable diagnostic tool. Videokeratoscopy explains well-known visual impairments related to dry eye and, along with lipid film interferometry, provides insight into tear film dynamics. The importance of tear film proteins is underestimated. Among therapeutics for symptomatic relief hyaluronic acid proved to be particularly useful but also the sequence of lid hygiene, warm compresses and lid massage is fundamentally important. The effectiveness of punctum plugs is ascribed considerably to a more efficient impact of essential tear film components. Topical cyclosporine A, INS365, 15(S)-HETE as well as topical androgens represent a whole new class of drugs for causal therapy of dry eye.

[Drainage systems in glaucoma surgery]. / Drainagesysteme in der Glaukomchirurgie.

Glaucoma drainage devices, also known as aqueous shunts (AS) are widely used in the USA. They consist of a silicone tube that is inserted into the anterior chamber and connected to a plate made of silicone or polypropylene, the explant. The latter is positioned between the recti muscles and over several weeks the surrounding tissue forms a fibrous bleb around the plate. This serves as a permanent filtration reservoir.Recurrent failure of filtrating surgery is the main indication for the use of AS. Other indications include situations in which the formation of a filtering bleb seems to be unpromising because of extensive conjunctival scarring. Qualified success has been achieved for many years in 50-100% of the eyes treated depending on patient selection. The most serious complication is postoperative hypotonia that can lead to serious chorioidal detachment, suprachorioidal hemorrhage, flat anterior chamber and corneal decompensation. To avoid this complication some devices, i.e.the Ahmed Glaucoma and the Krupin valve have integrated mechanisms to sustain a residual intraocular pressure. With other devices i.e. the Molteno and the Baerveldt devices, the tube has to be temporarily ligated until bleb formation has started. On the other hand fibrous infiltration of the bleb 1-4 months after the surgery often leads to a reversible rise in introcular pressure, which can be treated by massaging the bulbus, needling the bleb or injection of antimetabolites. There are no obvious differences between the various forms of AS with regard to the success of pressure regulation. In summary,by close scrutiny of indications and management of complications,drainage systems are a useful option in the management of complicated glaucoma that carry a high risk of failure from conventional filtering surgery.

[Better evaluation of HRT (Heidelberg Retina Tomography) images by 3-dimensional display]. / Bessere Auswertung von HRT-Aufnahmen durch dreidimensionale Darstellung.

BACKGROUND: The Heidelberg retina tomograph (HRT) is routinely used for the analysis of the structures of the eye ground (glaucoma diagnosis). The Dresden 3D-display, developed by the Technical University Dresden, is an autostereoscopic display which facilitates the three-dimensional presentation of geometrical data. The aim of this study was to test whether the spatial presentation improves the precision of measurements. METHODS: Out of the patients who attended our hospital for glaucoma treatment within the past 3 years, 17 (9 women and 8 men) were chosen on grounds of a long follow-up time. In addition the patients had to have had at least 4 HRT examinations (mean: 5.29). The patients data was explored in three ways: 1. regular HRT examination, 2. manual follow-up HRT examination and 3. examination with the Dresden 3D-display. RESULTS AND CONCLUSIONS: The measurements performed with the Dresden 3D-display showed a significantly higher precision compared to traditional HRT measurements. With spatial presentation a better assessment of the measured HRT data is possible.

[Osteo-odonto-keratoprosthesis. A summary of 6 years surgical experience]. / Die Osteo-Odonto-Keratoprothese. Ein Resümee nach sechs Jahren operativer Erfahrung.

PURPOSE: In patients with severe corneal scarring and vascularisation, corneal grafts have a high risk of failure. In those patients an osteo-odonto-keratoprosthesis (OOKP) can be performed. METHOD: We performed OOKP in eight patients in all with ocular pemphigoid, severe alkali burns, or repulsion of a corneal graft. Each of the patients had finger-counting visual acuity or less. The OOKP consisted of a PMMA cylinder 8 mm long, with a diameter of 3-4 mm, and from a root of the patient's tooth. This was implanted in the cornea and covered with buccal mucosa. RESULTS: The medium follow-up was 3 years. The implants are now well incorporated. The best visual acuity was between 0.6 and 0.9 in four patients with intact retinas. In the remaining patients, visual acuity was dependent on the posterior segment findings. The visual field was centred. Five of the eight patients had vitreous bleeding after the operation that was spontaneously absorbed. Revision of the mucous coverage was necessary in four patients, and one of them had a severe inflammation with partial absorption of the bone and tooth implant. One patient developed a secondary angle-closure glaucoma and was treated successfully by implantation of an Ahmed valve. Two patients developed membranes behind the cylinder that were successfully removed. There was no loss of any prosthesis during follow-up. CONCLUSIONS: In impasse in severe corneal scars, the osteo-odonto-keratoprosthesis is still indicated and shows good results in visual rehabilitation of patients.