[Postoperative Follow-Up of Glaucoma Drainage Devices]. / Nachsorge von epibulbären Glaukomdrainageimplantaten.

There is an increasing trend towards using glaucoma drainage implants. The postoperative management of such devices depends on their technical characteristics and specific complications. The Baerveldt glaucoma implant with its larger surface area has been shown to lower mean intraocular pressure more effectively than the Ahmed-FP7 implant. As a non-valve implant, however, it has been associated with a higher rate of severe complications, particularly ocular hypotension. Moreover, glaucoma implants may induce diplopia if they interfere with extraocular muscles. Topical treatment with antibiotics and steroids is necessary in cases of intraocular inflammation. In refractory cases, the tube may even have to be removed. Surgical reposition of the tube may be indicated when it is severely dislocated. Increased intraocular pressure is primarily treated by pressure-lowering medications during postoperative follow-up. If topical glaucoma medication is insufficient to control increases in intraocular pressure due to encapsulation, a second implant may be considered or the capsule surrounding the implant may be excised to reduce outflow resistance or additional cyclodestructive procedures can be performed. Chronic hypotension may be treated with tube ligation or occlusion. Severe corneal oedema may require lamellar keratoplasty. Conjunctival erosions with tube exposure or tube retractions also require surgical correction.

Clinical and genetic findings in a family with NMNAT1-associated Leber congenital amaurosis: case report and review of the literature.

BACKGROUND: Leber congenital amaurosis (LCA) is a severe retinal dystrophy, typically manifesting in the first year of life. Mutations in more than 18 genes have been reported to date. In recent studies, biallelic mutations in NMNAT1 encoding nicotinamide mononucleotide adenylyltransferase 1 have been found to cause LCA. PURPOSE: To broaden the knowledge regarding the phenotype of NMNAT1-associated LCA. METHODS: Clinical ophthalmologic examinations were performed in two sisters with LCA. Whole exome sequencing was performed in one of the affected girls, with subsequent segregation analysis in the affected sister and unaffected parents. The literature was reviewed for reports of NMNAT1-associated LCA. RESULTS: Exome sequencing revealed the known NMNAT1 mutation c.25G>A (p.Val9Met) in a homozygous state. Segregation analysis showed the same homozygous mutation in the affected younger sister. Both parents were found to be heterozygous carriers of the mutation. The two girls both presented with severe visual impairment, nystagmus, central atrophy of the pigment epithelium, and pigment clumping in the periphery before the age of 6 months. Retinal vessels were attenuated. Both children were hyperopic. In the older sister, differential diagnosis included an inflammatory origin, but electrophysiology in her as well as her sister confirmed a diagnosis of LCA. Pallor of the optic nerve head was not present at birth but developed progressively. CONCLUSIONS: We confirmed a diagnosis of NMNAT1-associated LCA in two siblings through identification of the mutation (c.25G>A [p. Val9Met]) in a homozygous state. In infants with non-detectable electroretinogram (ERG), along with severe congenital visual dysfunction or blindness and central pigment epithelium atrophy with pigment clumping resembling scarring due to chorioretinitis, LCA due to NMNAT1 mutations should be considered.

[Medial rectus tendon elongation with bovine pericardium for type 1 Duane's retraction syndrome]. / M.-rectus-internus-Sehnenverlängerung mit bovinem Perikard bei Duane-Retraktionssyndrom Typ 1.

BACKGROUND: Some patients with esotropic Duane's retraction syndrome (type 1) adopt a head turn to gain binocular vision. For some patients recession of the ipsilateral medial rectus muscle is not sufficient to eliminate head turn and squint angle. Surgery with tendon elongation allows the correction of larger angles and maintains a sufficient arc of contact. We report our results and experience. METHODS: We retrospectively reviewed the medical records of 10 patients with unilateral, esotropic Duane syndrome type 1 who had tendon elongation with bovine pericardium to correct a head turn or squint angle. Two patients had primary surgery with tendon elongation due to preoperative excessive angles, eight patients had tendon elongations as secondary procedures. Nine of the patients had their follow-up examination at least six weeks after surgery. RESULTS: The median preoperative angle of squint in primary position was + 27.5 pdpt, the median postoperative angle + 0 pdpt. The median dose effect relation for secondary interventions was 2.4 pdpt reduction of squint angle/mm surgery, for one patient with primary surgery and long-term follow-up 2.75 pdpt/mm. The median, preoperative head turn of seven patients with preoperative binocular functions was 20°. Postoperatively, six patients with long-term follow-up showed a median head turn of 0°. The median dose-effect relation was 3.3° reduction of head turn/mm surgery. All nine patients with long-term follow-up had a maximal head turn of 10°, six of the patients had no persisting head turn. Binocular functions were stable or better than preoperatively. CONCLUSIONS: For patients with retraction syndrome type 1, tendon elongation of the medial rectus muscle using Tutopatch® is a good option for secondary interventions or excessive preoperative squint angle or head turn.

Inferior rectus muscle recession as a treatment for vertical diplopia following cataract extraction.

BACKGROUND: Persistent vertical diplopia may occur after cataract surgery as a rare complication of retro- or parabulbar anesthesia. This is probably caused by structural changes in the muscles, altering muscular elasticity and function and thus complicating setting of the dosage for corrective strabismus surgery. The aim of our study was to investigate the effect of strabismus surgery in this specific motility disorder. METHODS: The findings from 15 consecutive patients (six women, nine men, median age 76 years), who had undergone initial strabismus surgery in our eye clinic between 2007 and 2010 due to vertical diplopia following cataract surgery, were investigated retrospectively. In all cases, cataract surgery had been performed under retro- or parabulbar anesthesia. RESULTS: Preoperatively, all affected eyes (five right eyes, ten left eyes) showed hypotropia with elevation deficiency and overaction of the inferior rectus muscle and/or superior oblique muscle on down-gaze. The median vertical deviation in primary position was 9.1 deg (min. 4.6, max. 24.7), measured with the alternate prism cover test, and 8 deg (min. 3.5, max.18) at the tangent screen of Harms. In all cases, the inferior rectus muscle was recessed 3 to 6 mm (median 3.5 mm). On the first day after surgery, the median angle of squint in primary position was 2.3 deg (min. 0, max. 10.2), when measured with the alternate prism cover test, with a mean dose-effect relationship of 1.8 ± 0.7 deg angle reduction per millimetre recession (median 1.9 deg/mm). In the postoperative period, eight patients examined after 2 to 20 months (median 3.5 months) showed a median vertical deviation of 5.7 deg (min. 1.7, max. 11.3), with a mean dose-effect relationship of 1.7 ± 1.3 deg/mm (median 1.8 deg/mm), but the values ranged widely. Four patients were not examined but interviewed by telephone. There was no feed-back from three patients. Six of 12 follow-up patients had no complaints, three had prisms to correct a persisting angle, and three patients needed further squint surgery. CONCLUSIONS: The efficacy of inferior rectus muscle recession for correction of hypotropia following cataract surgery with local anesthesia ranged widely. In this condition, operating on one muscle is a good option for correction of squint angles of less than 12 deg. Squint angle enlargement can occur in the postoperative course, and may necessitate further surgery.

[Diagnostics, clinical aspects and genetics of congenital corneal opacities]. / Diagnostik, Klinik und Genetik kongenitaler Hornhauttrübungen.

BACKGROUND: Congenital corneal opacities are comparatively rare diseases with high amblyogenic potential. PURPOSE: The present work provides an overview of the diagnostics, clinical aspects and genetics of congenital corneal opacities. METHODS: A literature search was carried out to compile an overview and illustration with own clinical case examples. RESULTS: Differentiated diagnostics are of high importance in the treatment of patients with congenital corneal opacities. A close cooperation between the medical departments involved and also the parents is absolutely essential. The structured classification of congenital corneal opacities provides the basis for a targeted treatment. DISCUSSION: The causes and the clinical symptoms of congenital corneal opacities are manifold. The correct diagnosis should be made early and in an interdisciplinary manner. Based on this, conservative and surgical treatment measures can be planned and an impending development of amblyopia can be specifically counteracted.

[Neuro-ophthalmological and ophthalmological findings in Joubert syndrome]. / Neuroophthalmologische und ophthalmologische Befunde beim Joubert-Syndrom.

BACKGROUND: Joubert syndrome (JS) belongs to the ciliopathies and is a mostly autosomal recessively inherited disease (in the case of OFD1 mutations, JS is an X-linked trait). It is characterised by midbrain-hindbrain malformations with developmental delay, hypotonia and ataxia and a broad spectrum of other facultative findings. The aim of our study was to examine the ophthalmological and neuro-ophthalmological features of JS in our patients and to compare our findings to those of other studies. METHODS: In a retrospective study we evaluated the ophthalmological and neuro-ophthalmological findings of 9 consecutive patients who met the diagnostic criteria of JS. RESULTS: All patients had abnormalities of ocular motility, 4/9 used head thrusts to shift gaze (oculomotor apraxia OMA). In 6/8 patients, the optokinetic reflex (OKN) was absent. Furthermore, 8/9 children showed nystagmus, mostly see-saw nystagmus. Manifest strabismus was found in 8/9 while 3/9 had a retinopathy with either abnormal ERG and/or fundus appearance with or without visual impairment. Chorioretinal colobomata were present in 5/9 cases. Two patients showed a unilateral congenital ptosis, one a facial nerve paresis. CONCLUSIONS: The early neuro-ophthalmological findings in JS are not pathognonomic, but may lead to the diagnosis of JS. The syndrome should be suspected in patients with nystagmus, especially see-saw nystagmus, and abnormal OKN and/or OMA, and/or colobomata of the fundus, and further paediatric examinations should be initiated.

Comparison of standard endoscopic submucosal dissection (ESD) versus an optimized ESD technique for the colon: an animal study.

BACKGROUND AND STUDY AIMS: Endoscopic submucosal dissection (ESD) is a promising therapeutic technique for en bloc resection of large gastrointestinal tumors. However, this technique has disadvantages such as a long intervention time, complexity of the procedure, and a higher rate of complications. The primary aims of the study were to show the feasibility of ESD in the pig colon and to evaluate a new ESD technique comprising the use of a newly developed hybrid knife for colon procedures combining RF (radiofrequency) application and a distance-dependent water-jet application. MATERIALS AND METHODS: ESD was conducted at three different locations in the colon according to the computer-generated randomization list, using either the standard technique (injection needle, flex knife, and hook knife as therapeutic instruments and DRY CUT and SWIFT COAG as RF currents), or the new ESD technique (hybrid knife as the therapeutic instrument combined with the new cutting mode ENDO CUT D) in 12 healthy pigs. The perforation and bleeding rates were documented and statistically analyzed. Intervention time, resected specimen size, thermal and mechanical damage of the resection bed, and number of instrument changes required were also recorded. RESULTS: A total of 16 and 18 ESD procedures were performed by the standard and new techniques, respectively. Complete en bloc resection was achieved in all cases. The standard ESD technique showed a perforation rate of 25 % (4/16) whereas the new ESD technique resulted in a 5.5 % perforation rate (1/18) ( P = 0.035); bleeding rates were similar. The new ESD technique was significantly safer compared with the standard ESD technique. CONCLUSIONS: A new ESD technique for the successful en bloc resection in thin-walled regions such as pig colon has been described. This procedure is as effective as the standard procedure but is easier to handle and significantly safer.

Kestenbaum procedure on the vertical rectus muscles with simultaneous compensation of the induced cyclodeviation for nystagmus patients with chin-up or chin-down head posture.

BACKGROUND: Kestenbaum surgery is performed for nystagmus-related abnormal head posture, and symmetrically changes the position of both eyes to shift the null point to the primary position. Most patients with infantile nystagmus have their null point zone in a lateral gaze position. Less frequently, surgery can be performed to reduce chin-up or chin-down head posture. We report indications for, and the results of eight consecutive interventions performed according to the Kestenbaum principle for the reduction of a chin-up or chin-down head posture. METHODS: In a retrospective study, the clinical findings for eight patients who consecutively underwent treatment in the University Eye Hospital of Cologne between 2001 and 2007 were investigated. The patients were aged 6 to 16 years; median age was 6.5 years. For all patients, surgery was to correct a chin-up or chin-down head posture due to infantile nystagmus. Preoperatively, five patients showed a chin-down, three a chin-up head posture. All vertical rectus muscles were recessed or tucked between 6 and 7 mm; the resulting cyclodeviation was reduced by an intervention on the superior oblique muscles (6 to 8 mm tucking, in the case of chin-down, or recession in the case of chin-up head posture). RESULTS: Surgery was successful in seven of the eight patients, with a reduction of the vertical head posture to less than 10 degrees. In the cases of chin-down posture, head posture was reduced to between 0 degrees and a maximum of 20 degrees in one case postoperatively (before the operation 20 degrees to 35 degrees ); in the cases of chin-up posture, to less than 8 degrees (before the operation 25 degrees to 35 degrees). One case showed no postoperative improvement in chin-down posture but a head turn to the left of up to 20 degrees; another case had a remaining chin-up posture of 8 degrees with a right turn of 15 degrees . Binocular vision was better or the same in all cases after surgery. CONCLUSION: For nystagmus patients with chin-up or chin-down head posture, surgery for bilateral parallel shifting of the eyes can considerably improve the head posture. It is possible to compensate the induced cyclodeviation at the same time by bilateral surgery on the superior oblique muscles.

[Surgical options for eye muscle surgery in third nerve palsy]. / Augenmuskelchirurgische Differenzialtherapie bei Okulomotoriusparesen.

Uni- or bilateral third nerve palsies account for about one third of cranial nerve palsies affecting ocular motility. Due to the large nuclear complex of the third nerve and due to the multiple effector muscles of the third nerve, incomplete palsies are common. When conservative treatment is insufficient and a potential remission did not occur, surgical intervention on the extraocular muscles may be indicated to reduce diplopia, establish a field of binocular single vision or relieve annoying head postures or improve the patient's appearance. Standard procedures in strabismus surgery such as simple recessions or strengthening procedures often do not yield permanent effects under the conditions of third nerve palsies so that transposition procedures may be required. Special considerations in individual indications, e. g., concerning binocular prognosis, possible misinnervation and potential accompanying fourth nerve palsy are discussed in general and illustrated with case reports.

[Bilateral modified Hummelsheim procedure in severe bilateral abduction deficiency]. / Muskeltransposition modifiziert nach Hummelsheim bei bilateralen Abduktionseinschränkungen.

BACKGROUND: Bilateral sixth nerve paralysis is a rare motility disturbance. The functional and cosmetic problems, operative management and postoperative outcome in three patients are presented. MATERIAL AND METHODS: We report on the pre- and postoperative findings of three patients who in one operative session received bilateral transposition surgery in modification of the Hummelsheim procedure. RESULTS: All three patients postoperatively showed good cosmetic results with no significant head posture for far and near fixation. The abduction deficiency was reduced. In one case a field of binocular single vision at far fixation was established. This field was positioned centrally and measured 15 degrees in diameter. No intraoperative or postoperative complications occurred. CONCLUSION: Simultaneous bilateral transposition surgery as a modified Hummelsheim procedure can reduce head turn in patients with severe bilateral abduction deficiencies and may reestablish limited binocular single vision. In regard to their psycho-social interactions, the patients benefit from the diminished angle of squint.

[Influence of two different cameras on the spectrometric measurement of oxygen saturation]. / Einfluss von unterschiedlichen Kameratypen auf die spektrometrische Messung der Sauerstoffsättigung.

OBJECTIVES: Oxygen saturation in retinal vessels can be measured by spectrometry. However, there are no studies on the influence of different camera chips on these measurements. The presented study reports the effect of two different camera chips ("1-CCD" vs. "3-CCD") on the spectrometric measurements in the same patients. METHODS: 61 eyes of 61 patients were included in this study. The study was approved by the local ethics commission. Patients were separated in 3 groups: the first group contained healthy volunteers, the second group patients with diabetes mellitus but without previous laser treatment, the third group included patients with diabetes mellitus and previous laser coagulation treatment. The oxygen saturation was calculated from the difference between wavelengths on and right next to the retinal vessel. This methodology uses the different absorption spectra of oxy- and deoxyhaemoglobin. RESULTS: All 3 groups demonstrated valid outcomes of the retinal oxygen saturation in arterial and venous vessels. No significant differences we found in the arterial-venous oxygen difference between the two different camera chips (group 1 p = 0.063, group 2 p = 0.204, group 3 p = 0.059). CONCLUSION: As no significant differences could be found between the two camera chips, the less expensive system should be used if the spectrometric measurement of oxygen saturation is added to an analysis system already established on the market.

Endoscopic ultrasound-guided application of a new internally gas-cooled radiofrequency ablation probe in the liver and spleen of an animal model: a preliminary study.

BACKGROUND AND STUDY AIMS: In a previous study, a new flexible bipolar hybrid cryotherm probe was applied with success to the pancreas of a living pig. Here we evaluated feasibility, efficacy, and safety of its application to the porcine liver and spleen. MATERIAL AND METHODS: Ten applications to the liver and nine to the spleen were performed in 19 pigs. Power input (16-18 W) and simultaneous cooling with CO(2) (standardized pressure: 675 psi) as the cryogenic agent were investigated. Application time varied from 120 seconds to 900 seconds. The ablation area was measured by endoscopic ultrasound (EUS) after ablation (T0), and before euthanasia (T1). Gross pathology (T2) and histology after necropsy represented the gold standard. The interval from treatment to euthanasia was 1 or 2 weeks. RESULTS: For both organs the correlation between EUS and gross pathology was good (correlation coefficient R(liver) = 0.71; R(spleen) = 0.73). EUS tended to overestimate the area of the ablated zone. EUS observed a time-dependent ablation area: we demonstrated a positive trend of lesion size (T1) over time in liver tissue (R = 0.51 (P = 0.1)). In the spleen we found a clear correlation of lesion area T2 and application time (R = 0.75, P = 0.01). There were no complications. CONCLUSIONS: Selective EUS-guided transgastric cryotherm ablation of the liver and spleen in a pig model is feasible and safe. The new bipolar probe creates a time-dependent ablation area without any complications, and opens a field of new potential indications of RF-ablative therapies.

Long gap esophageal atresia and arterial circle of Willis variant leading to ischemic stroke during gastric transposition.

In children, strokes occur with a frequency of 2 to 13 per 100,000. Risk factors include hematological, embolic and anatomical anomalies. But often the exact cause of strokes in pediatric patients remains unclear. We report here on a patient with long gap esophageal atresia, who suffered an ischemic stroke during gastric transposition. Postoperative assessment revealed a cerebral vascular variant of the circle of Willis. Follow-up clinical controls showed a favorable course. Today, at the age of 14 months, almost no neurological deficits are evident. To the best of our knowledge, no description of vascular cerebral complications combined with esophageal atresia can be found in the literature.

[Strabologic and neuro-ophthamologic aspects of childhood cancer]. / Strabologische und neuroophthalmologische Aspekte kindlicher Tumorerkrankungen.

Pediatric oncology has achieved major progress by continuous optimization of diagnostic and therapeutic approaches. In the interdisciplinary team, the ophthalmologist plays an important role. In the field of strabismus and neuro-ophthalmology clinical symptoms as strabismus, visual loss, anisocoria, visual field defects, and involuntary eye movements may be key indicators of childhood cancer. The appropriate diagnostic workup as well as the diagnostic and therapeutic steps during the course of the disease are important often requiring individually tailored approaches.

[Extra-ocular muscle surgery using combined topical and subconjunctival anesthesia]. / Augenmuskeloperationen in kombinierter Tropf- und Subkonjunktivalanästhesie Indikationsspektrum, Technik und Risikoprofil.

A retrospective study of a consecutive series of 284 cases of strabismus surgery under local anesthesia is presented. A total of 284 operations on the extraocular muscles, performed with topical and subconjunctival application of local anesthetics-in some cases combined with anesthesiological sedation and monitoring-were analyzed retrospectively for adverse effects or complications caused by the type of anesthesia chosen. No ophthalmological complications caused by the mode of anesthesia and no vital complications occurred. In three cases, the intended surgery could not be fully completed due to discomfort of the patient caused by pain perception. In this case series, combined topical and subconjunctival anesthesia in strabismus surgery had a low frequency of complications.

Finite-element-modeling of egg white as a substitute for tissue coagulation during bipolar radiofrequency-induced thermofusion.

Radiofrequency-induced thermofusion is a frequently used electrosurgical procedure for the sealing of blood vessels. A disadvantage of vessel sealing instruments is that the generated thermal energy spreads to the surrounding tissue and may irreversibly damage it. This is particularly problematic when operating close to sensitive structures such as nerves. Given their advantages, there is nonetheless a lot of interest in using bipolar vessel sealing for surgical procedures. To select instruments that may be safely used in such cases, it is important to reliably quantify the thermal spread to the surrounding tissue. Mathematical models can help to evaluate the transient behavior, that is the evolution of the thermal spread over time, more precisely. A finite element model allows for a detailed analysis of inhomogeneities in the spatial temperature distribution. As a first step towards a finite model of the bipolar vessel sealing process, a model of the coagulation of chicken egg white is presented here. Egg white has thermal and electrical properties that are very similar to tissue, making it suitable as a substitute for the analysis of the coagulation process. It has the additional advantage, that the spatial and temporal evolution of the thermal spread can be visually gauged. The presented model describes the experimentally observed spatial temperature distribution, the shape of the coagulated egg white, and the formation of hotspots. Furthermore, it is shown that the model can correctly predict the shape of the coagulated egg white in further experiments.

New onset of crossed eyes in an adult.

A 77-year-old woman presents with a seven-year history of an isolated slowly progressive esotropia with bilateral abduction defects. The only potential cause discovered was dolichoectasia of the intracavernous carotid arteries.

Distributed changes in rat brain DNA synthesis with long-term habituation and potentiation of the perforant path-granule cell synapse.

The involvement of brain deoxyribonucleic acid (DNA) synthesis in adaptive neural events was studied in the adult rat during long-term habituation (LTH) or potentiation (LTP) of the perforant path-granule cell synapse. Male Long-Evans rats were given 50 muCi [3H]thymidine intraventricularly under urethane anesthesia. Soon thereafter, field excitatory postsynaptic potential (EPSP) slope and population spike were monitored from the right dentate gyrus before and at various times (5, 10, 15, 60 min) following the delivery to the ipsilateral perforant bundle of a low frequency (LFS: 1.0 Hz, 160 s) or a high-frequency train (HFS: 400 Hz, 200 ms), repeated once after 5 min. Unstimulated implanted rats served as controls. DNA synthesis was evaluated by the incorporation of the radioactive precursor into DNA of several brain areas at the end of a 1 h incorporation period. In CA1, LTH and LTP increased DNA synthesis by 30% on the stimulated side. In the entorhinal cortex, LTH but not LTP increased DNA synthesis (by 30%) on the stimulated side. Conversely, in the frontal cortex, LTP but not LTH increased DNA synthesis (by 100%) on both sides. Long-lasting changes in synaptic efficacy covaried non-linearly with DNA synthesis in mono- and polysynaptically stimulated hippocampal regions, and in functionally associated neocortical areas. The co-variations of population spike amplitude were positive for LTH and negative for LTP in the dentate gyrus and frontal cortex of both sides, and in CA3/CA1 of the stimulated side, indicating higher DNA synthesis at lower values of LTH and LTP, and viceversa. Further, regional cross-correlation analyses revealed a high degree of synchronization among brain sites, following low- or high-frequency train pulses, indicating that (i) extra-target sites participate on the stimulated and on the contralateral side, and (ii) small distributed changes take place across the sampled neural networks. A modulatory role of information flow on brain DNA synthesis is inferred to take place in a diffuse, distributed manner.

Modified transposition procedure of the vertical recti in sixth nerve palsy.

PURPOSE: To report a modified transposition procedure of the vertical recti for severely limited abduction of the globe caused by sixth nerve palsy and to compare this with the Hummelsheim transposition procedure. METHODS: Retrospective study of 13 eyes of 12 patients that had Hummelsheim transposition procedure and 19 eyes of 17 patients that had modified transposition procedure of the vertical recti for severely limited abduction of the globe caused by sixth nerve palsy. The modified transposition procedure joins lateral strips of the vertical recti and sutures this junction to the lateral rectus muscle. Functional results of the Hummelsheim procedure are compared with functional results of the modified transposition procedure. RESULTS: Abductive capacity improved by 4.19 +/- 1.67 mm in the Hummelsheim group and 4.08 +/- 1.7 mm in the modification. The angle of squint changed from +22.33 +/- 6.74 degrees to -0.20 +/- 2.61 degrees in the Hummelsheim group and from +25.54 +/- 5.66 degrees to +0.95 +/- 5.26 degrees in the modification group. The functional results as to abductive capacity and postoperative angle of squint showed no significant difference between the two methods (P >.05, t test). The modification was less time consuming. CONCLUSIONS: A modification of the transposition techniques of eye muscles in sixth nerve palsy is introduced. Its functional results are comparable to the classic technique of Hummelsheim. Operative risk and trauma are reduced, because the technique avoids scleral stitches and was found to be less time consuming than the Hummelsheim procedure.

Unscheduled brain DNA synthesis, long-term potentiation, and depression at the perforant path-granule cell synapse in the rat.

We investigated the effect of long-term potentiation (LTP) of the perforant path-granule cell synapse, on the synthesis of DNA in the target area and in polysynaptically stimulated hippocampal (CA3/CA1) and cortical areas (entorhinal, temporal, and occipital cortices) in the rat. The contralateral nonstimulated side was used as a control. The degree of LTP was indexed by the field EPSP and population spike amplitude recorded in the dentate area of the stimulated side before and after high frequency stimulation (250 Hz, 250 ms) every 30 min. DNA synthesis was evaluated in tissue homogenates after a 3-h period of incorporation of 3H-thymidine. DNA synthesis was significantly lower in the stimulated side in the hippocampal cortex CA3/CA1 (-25%), and in the entorhinal cortex (-50%), but not in the dentate area. In addition, the occurrence of preparations without expression of LTP allowed the analysis of unscheduled brain DNA synthesis (UBDS) in a supposedly long-term depression (LTD) subgroup. UBDS was higher in the group without LTP (no-LTP group) than in that with a significant LTP expression (LTP-group) on both sides of the brain. Furthermore, correlative analyses revealed that UBDS covaried with LTP of the EPSP (but not of population spike) in the dentate area and in extratarget hippocampal subregions on both sides and in dorsal cortex on the stimulated side. Further, regional crosscorrelation analyses revealed a high degree of coupling among brain sites following LTP.(ABSTRACT TRUNCATED AT 250 WORDS)