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Biomedical subjects

P Senn

Publications and source records attributed to P Senn.

At least 19 recordsLinked to original sources
PubMed2003

Changes on diffusion-weighted MRI with focal motor status epilepticus: case report.

Transient imaging abnormalities, including changes on diffusion-weighted imaging (DWI), may be seen in focal status epilepticus. The changes on DWI provide am insight into the pathophysiology. We report a 53-year-old man with focal motor status epilepticus involving the left hand, arm and face with focal slowing on EEG. The apparent diffusion coefficients (ADC) were higher in the affected hemisphere than on the other side. At 10 days and 6 weeks after the end of the seizures, we saw normal ADCs and atrophy of the affected hemisphere. We conclude that the MRI findings indicate both cytotoxic and vasogenic oedema during seizure activity and subsequent loss of brain parenchyma.

Arm↗
PubMed2001

[Ocular barostress and barotrauma. A study of 15 scuba divers].

BACKGROUND: During SCUBA-diving, relative changes of the pressure in the diving mask, compared to the environmental pressure, are transmitted to the eye and to the periocular tissue. Barotrauma results from lack of pressure equilibration. MATERIAL AND METHODS: In 15 divers (6 experienced, 9 beginners) the pressure difference (delta-p) between inside and outside of the diving mask was measured every second during recreational SCUBA-diving. Data were transmitted wireless to a modified standard diving computer. An overall dive time of 323 minutes was analysed. RESULTS: Mean delta-p was 14.8 mbar (-44 to , std.dev. +/- 9), it was not dependent on the diving depth (r2 = 0.0004). Delta-p oscillated between 0 and 25 mbar (0-19 mm Hg), parallel to respiration. Negative delta-p values were 9.5 times more frequent in beginners than in experienced divers. Negative pressure peaks (changes > or = 10 mbar for more than 6 sec) occurred in the beginner group exclusively (p = 0.01). CONCLUSIONS: During SCUBA diving, ocular tissues undergo oscillating changes of environmental pressure, parallel to respiration. This may be important in eyes with previous surgery. Pressure peaks, leading to severe ocular barotrauma, are easily avoidable.

Adult↗
PubMed2000

The formation and regression of a flow-related cerebral artery aneurysm.

The authors report a patient with an aneurysm of the right cerebral posterior communicating artery (PCoA) developing after thrombotic pseudo-occlusion of the right internal carotid artery (ICA). The aneurysm regressed spontaneously subsequent to ipsilateral ICA endarterectomy and reversal of blood flow in the PCoA. The formation and regression of the aneurysm was well documented by repeat cerebral digital subtraction angiography studies, computed tomography and magnetic resonance imaging. The authors conclude that the formation and regression of this 'flow-related' aneurysm was associated with hemodynamic changes in blood flow of the right PCoA and the right ICA.

Aged↗
PubMed2000

Central and peripheral pressure measurements with the Goldmann tonometer and Tono-Pen after photorefractive keratectomy for myopia.

To compare the accuracy of Goldmann tonometry with that of the Tono-Pen(R) in measuring intraocular pressure (IOP) after photorefractive keratectomy (PRK). Eye Clinic, Cantonal Hospital, Lucerne, Switzerland.Thirty-five eyes (25 patients) had PRK for a mean myopia of -6.2 diopters +/- 2.6 (SD). Intraocular pressure (IOP) measurements were performed first with the Goldmann tonometer and then with the Tono-Pen in 2 corneal locations: centrally in the usual manner and temporally. For the temporal measurements, the patient was directed to gaze nasally as the tonometer was placed perpendicular to the temporal portion of the cornea and with the rim of the tonometer positioned just inside the limbus of the cornea. Subsequently, similar measurements were made with the Tono-Pen. Measurements were performed before and 1 and 3 months after PRK. Preoperative IOPs measured centrally and temporally were similar. After PRK, the central pressure readings with the Goldmann tonometer and the Tono-Pen were between 1.8 and 2.3 mm Hg lower than those measured temporally. The differences were statistically significant (P <.0001). Central corneal pressure readings obtained with either the Goldmann tonometer or the Tono-Pen after myopic PRK are inaccurate. Measurements over the temporal part of the cornea are likely more reliable.

Adult↗
PubMed2000

[Intraocular pressure after phacoemulsification and implantation of silicone plate haptic intraocular lenses without viscoelastics].

BACKGROUND: A rise in intraocular pressure (IOP) after cataract operation is a well known problem. Avoidance of the use of viscoelastics seems to solve the problem. PATIENTS AND METHODS: The IOP was measured in a group of 33 eyes of 33 patients one day before, as well as 6 hours, 24 hours, and 7 days after phacoemulsification and implantation of a foldable silicone plate haptic intraocular lens without viscoelastics and by means of an injector and of the anterior chamber maintainer. RESULTS: Mean preoperative IOP was 16.1 +/- 3.9 mm Hg (range 10 to 28 mm Hg). Postoperatively mean IOP was 12.3 +/- 3.3 mm Hg (range 5 to 18 mm Hg) after 6 hours (p < 0.0001), 13.8 +/- 2.8 mm Hg (range 7 to 19 mm Hg) after 24 hours (p = 0.032), and 15.5 +/- 3.4 (range 10 to 24) after one week (p = 0.39). In none of the eyes was the pressure in the first 24 hours higher than 18 mm Hg. When excluding the 4 patients with glaucoma and PEX or when taking them as a separate group, the results were similar. CONCLUSIONS: Pressure elevation after cataract operation without the use of viscoelastic substances can be avoided, thus contributing not only to lower costs but also to a higher safety.

Adjuvants, Immunologic↗
PubMed2000

[Prognostic factors and results after surgical treatment of idiopathic macular holes, stage 2 and 3].

PURPOSE: To determine prognostic factors, functional outcome and subjective rating after surgery for macular holes stage 2 and 3. METHODS: We studied 53 eyes of 49 patients undergoing vitreous surgery for macular holes stage 2 (46%) and 3 (54%). Mean follow-op was 114 weeks (32-204, std.dev. +/- 48), mean age 68.9 years (44-89, std.dev. +/- 6.8). 72% were female, 11% were pseudophakic, 19% phakic, 70% had a combined procedure (pars plana vitrectomy, phacoemulsification and IOL). Surgery consisted in a pars plana vitrectomy, peeling of epiretinal membranes and ILM, internal tamponade with SF6 (98%) resp. Si-oil in one case. Patients had to keep face-down position 6 x 20 minutes per day. RESULTS: The hole was completely closed in 90.6%. Anatomical failures included, 86% had an increase of VA, 41% = 5 lines (Final VA median 20/30, max. 20/20). No further increase of the retinal function occurred after 6 months. The visual result did not correlate with the duration of symptoms. 84% were satisfied with the outcome, subjective rating was not correlated with final VA or change of VA. 19% showed postoperative typical peripheral visual field defects. Visual field loss was not correlated with perioperative IOP elevation. CONCLUSION: Macular hole surgery has a high functional success rate. Postoperative visual field defects are an important problem.

Aged↗
PubMed1999

[Perioperative circulatory side effects of topical 5% phenylephrine for mydriasis].

PURPOSE: To study the systemic effects of topically applied 5% phenylephrine. To investigate intraoperative injection of epinephrine in the anterior chamber as an alternative. METHOD: 75 patients undergoing cataract surgery were randomized into three groups. In group 1, the pupil was dilated using topically 5% phenylephrine and 1% cyclopentolate, the patients blocked the lacrimal drainage system themselves by digital compression. Group 2 received the same drops, digital compression was performed by one of the investigators. In Group 3, no preoperative phenylephrine was used--instead, epinephrine 1:25,000 was injected in the anterior chamber at the beginning of surgery. Retrobulbar anesthesia was performed in a short narcosis with ketamine and propofol. RESULTS: Mean preoperative blood pressure values were higher than the day before. They fell during narcosis, to increase significantly after the injection of the local anesthetics. At the beginning of surgery they were back to prenarcotic values. Intraoperative blood pressure remained stable. Preoperative day values were found two hours postop. There was no significant difference in the circulatory behavior between the three groups. For mydriasis, intraoperative intracameral epinephrine was not as effective as preoperative phenylephrine. CONCLUSION: In normotonic or medically treated arterial hypertensive patients, preoperative mydriasis using 5% phenylephrine is safe--proceeding the way described above. Compression of the lacrimal drainage system can be performed by the patients effectively. Intraoperative intracameral epinephrine does not replace preoperative phenylephrine.

Administration, Topical↗
PubMed1997

Photoastigmatic refractive keratectomy for primary treatment and revision of myopic astigmatism.

PURPOSE: To evaluate the results in 43 eyes treated with a rotating mask for myopic astigmatism and followed for up to 1 year. SETTING: Lucerne Eye Clinic, Cantonal Hospital, Lucerne, Switzerland. METHODS: Thirty-two patients (42 eyes) were selected to have photoastigmatic refractive keratectomy (PARK). In 33% (14 eyes), this treatment was the second or third ablation. The Aesculap Meditec MEL 60 excimer laser was operated in toe scanning slit mode, and a rotating mask was used. To evaluate cylindrical shaping, vector analysis was performed. RESULTS: One year after PARK, mean uncorrected visual acuity in all patients (26 eyes) improved from 20/160 preoperatively to 20/40. Surgically induced astigmatism in 20 of 26 eyes (77%) was within +/- 1.00 diopter (D) of the targeted induced astigmatism. At 1 year, 81% of patients who had primary excimer laser treatment for myopic astigmatism equivalent to -10.00 D or less were within +/- 1.00 D of target refraction compared with 44% of re-treated eyes. CONCLUSION: The result of PARK in eyes with low to moderate degrees of myopic astigmatism was satisfactory. However, in eyes with extensive scarring and wound healing activity after the first ablation, re-treatment was less predictable.

Adult↗
PubMed1997

Glare sensitivity and visual acuity after excimer laser photorefractive keratectomy for myopia.

BACKGROUND: Following excimer laser photorefractive keratectomy (PRK), an increase in glare sensitivity and a reduction in contrast sensitivity can occur owing to changes in the cornea (structure and topography). In this study, an attempt was made to quantify and document objectively a change in those subjective perceptual factors. METHODS: Snellen visual acuity and disability glare were measured with the Berkeley glare test preoperatively as well as 1, 3, 6, 9, and 12 months postoperatively, after excimer laser photorefractive keratectomy (PRK) on 32 myopic patients (46 eyes). During the postoperative progress checks, haze was graded and contrast sensitivity was measured with the Vistech chart. All the data were statistically analysed by multiple regression. RESULTS: One year after PRK, a reduction in visual acuity (VA) measured with the low acuity contrast chart (10%) with and without glare could still be found, despite the fact that acuity measurements with a high contrast Snellen chart showed the same VA 6 months postoperatively as well as before the treatment. The lowest VA could be measured 1 month postoperatively; thereafter, the acuity increased despite the increase in haze that occurred during the first 3 months. CONCLUSION: Disability glare and a reduction in contrast sensitivity could be observed in most patients after PRK treatment with the Meditec laser system with its scanning slit. The future will show if new technology and a broader flattening area of 6 to 7 mm can minimise these postoperative complications.

Adult↗
PubMed1997

Interaction between silicone oil and silicone intraocular lenses: an in vitro study.

The objective of this study was to examine the interaction between silicone oil and silicone intraocular lenses (IOLs) in vitro. Six types of silicone IOLs were placed in silicone oil (1000 or 5000 centistokes) for 1 minute, 7 days, and 420 days. Slit-lamp examination, target photographs, and opacity measurements were performed. Optical measurements were repeated in a balanced salt solution after removal from the oil. The IOL surface was examined through scanning electron microscopy, and surface irregularities underwent x-ray spectroscopy. No changes were observed while the IOLs were stored in silicone oil, but in the balanced salt solution, the IOLs were observed to have a layer of silicone oil droplets that reduced the optical quality. Scanning electron microscopy showed that oil-coated foreign body particles were simulating IOL surface defects. After ultrasonic cleaning with ethanol, the oil layer was broken, and no damage to the IOL surface could be detected. The length of exposure to silicone oil, the type of oil, and the type of IOL were found to have no bearing on the interaction between silicone oil and silicone IOLs. Although no surface damage is incurred by silicone IOLs from silicone oil, the reduction in optical quality and fundus view due to remnant oil droplets seems to indicate that complex cases requiring silicone oil injection may contraindicate IOLs made of silicone.

Adhesiveness↗
PubMed1996

[Candida albicans spondylitis: successful treatment with fluconazole. 2 case reports].

Two patients suffering from candida albicans spondylitis in the lumbar spine are reported. Both had been operated on because of malignancy. One patient's clinical course was complicated by candida septicemia, and later on, serious candida endophthalmia developed. Conventional X-rays, combined with technetium scintigraphy, showed inflammatory destruction of the end plates of neighbouring vertebrae. Computerized tomography was done in the second patient, when an abscess was detected on both sides in the psoas muscle. Consecutively, operative removal and a spondylodesis were performed. Candida albicans could be isolated from removed discal material. Treatment by fluconazole for six months, in the first case in the beginning also by amphotericin B, lead to the healing of fungal spondylitis, accompanied by partial osseous consolidation.

Aged↗
PubMed1995

[Are we measuring the right intraocular pressure after excimer laser photorefractive laser keratoplasty in myopia?].

BACKGROUND: It is possible that the traditional method to determine the intraocular pressure after excimer-laser PRK is inaccurate. Measuring the pressure in the temporal part of the cornea might give the true values. METHODS: Intraocular pressure was measured with a Goldmann Applanation Tonometer and with the Tonopen, before and after PRK for myopia in the central and in the temporal parts of the cornea. The paired student t-test was used for statistical analysis. RESULTS: The results of central and temporal measurements before treatment were identical with both instruments. After PRK, central values were 2 to 3 mm Hg lower than temporal values when measured with a Goldmann Tonometer, and about 2 mm lower when measured with the Tonopen. The differences were highly significant (p < 0.0001 and p = 0.004 respectively). CONCLUSIONS: The intraocular pressure measured in the usual manner after excimer-laser PRK is lower than the temporally measured pressure. These differences could be caused by absence of the Bowman's membrane, thinning of the cornea and/or change of its topography.

Cornea↗
PubMed1995

Results of reshaping with the 193-nm excimer laser.

We report herein our experience with reshaping following primary photorefractive keratectomy (PRK). Reshaping was performed on 7 of 116 myopic eyes (6 patients) 6-12 months subsequent to initial treatment. We carried out reshaping on 5 eyes (4 patients) for either undercorrection or regression. The mean preoperative refraction was -6.9 D, and at 1 year postsurgery it was -0.3 D. At 6 months following reshaping, the mean refraction was -0.15 D and the average uncorrected visual acuity (VA) was 20/25. In one patient, retreatment was performed 6 months after initial PRK due to marked regression and deterioration of VA. At 9 months subsequent to reshaping, the VA had improved to 20/25 with spherical correction of -1.0 D. In another patient, the best corrected VA deterioriated from 20/40 (-13.5 D) to 20/80, with hyperopia of +3.5 D being combined with marked scarring. At 6 months following phototherapeutic keratectomy (PTK), the VA had improved to 20/50, with spherical correction of +1.0 D. In conclusion, these observations demonstrate that reshaping is a satisfactory mode of treatment in certain indications.

Adult↗
PubMed1995

Tapered transition zone and surface smoothing ameliorate the results of excimer-laser photorefractive keratectomy for myopia.

This report compares the results we obtained after photorefractive keratectomy (PRK) for myopia using different treatment modalities. PRK was performed on 35 eyes (group 2; mean refraction, -5.7 +/- 2.3 D) using a tapered transition zone (TTZ), smoothing of the corneal surface, and somewhat more steroids than usual. The results were compared with those obtained in another group of patients (group 1) with equally high myopia in whom these measures were not used. Quicker rehabilitation and stabilization of visual acuity (VA) and less regression were observed. An uncorrected VA of +/- 20/40 after 9 months was found in 94.4% of eyes in group 1 (P = 0.026). A refraction of +/- D after 9 months was found in 89% of eyes in group 2 and in only 58% of eyes in group 1 (P = 0.024). Haze reduction was quicker and stronger in group 2, and fewer patients in this group suffered loss of best corrected VA. The results of PRK of myopia can be ameliorated thanks to improved technique and increased experience.

Adult↗
PubMed1994

[2 years experience with the Excimer laser photorefractive keratectomy in myopia].

PATIENTS AND METHODS: Myopic PRK (Photorefractive Keratectomy) has been performed on 116 eyes (myopia of between -3.0 D and -25.5 D) in the eye clinic of Lucerne, since october 1990. 25 patients had both eyes treated, 7 eyes were retreated. RESULTS: Results are satisfactory for myopia of up to -10 D (-15 D); treatment of the higher myopia is problematic. CONCLUSION: Regression was the biggest problem in all patients, being the more pronounced the higher the ablation. Based on this experience recommendations for treatment are given.

Adult↗
PubMed1994

Correction of astigmatism with Excimer laser transverse keratectomy.

Transverse keratectomies with the Excimer laser were performed on seven eyes of 4 patients with a mean, naturally occurring astigmatism of 5.32D (SD 1.0), range 4.25 to 7.0D. One month later mean astigmatism was 3.46D (SD 1.35), 3 months later 3.8D (SD 1.35), rising to 4.3D (SD 1.6) after 6 months, and to 4.68 (SD 1.4) after 1 year. The refractive cylinder was reduced from a mean of 5.8D to 4.5D and the mean uncorrected visual acuity rose from 0.16 to 0.3. No serious complications occurred, and uncorrected visual acuity could be improved slightly. Excimer laser transverse keratectomy cannot be recommended as a good method to treat high degrees of naturally occurring astigmatism.

Adult↗
PubMed1994

Bubbles in the bleb--troubles in the bleb? Molteno implant and intraocular tamponade with silicone oil in an aphakic patient.

A 14-year-old aphakic girl who had had previous bilateral glaucoma surgery with a Molteno implant underwent pars plana vitrectomy and silicone-oil tamponade for proliferative-vitreoretinopathy retinal detachment in both eyes. The filtering bleb of the left eye was functional for 5 months before becoming available for histologic examination. We found numerous foreign-body granulomas coating the inner surface of the bleb, as well as intracellular and extracellular deposits of emulsified silicone oil in the wall of the bleb. In the fellow eye, the filtering bleb remained functional despite repeated vitreous surgery with silicone oil. Filtration in aphakic eyes with previous Molteno surgery and silicone-oil tamponade after vitrectomy may continue normally for a prolonged period of time, although emulsified oil droplets likely will have accumulated in the bleb and become incorporated in its fibrous capsule.

Adolescent↗