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Biomedical subjects

I Schipper

Publications and source records attributed to I Schipper.

At least 19 recordsLinked to original sources
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

Bilateral papilledema from a massive intracranial epidermoid cyst.

PURPOSE: To report an unusual case of bilateral papilledema from a large intracranial epidermoid cyst. METHODS: Case report. RESULTS: A 26-year-old man presented with visual loss, bilateral papilledema, and only a few neurological symptoms. Magnetic resonance imaging disclosed such a large lesion that his right cerebral hemisphere was compressed to one half its normal size. Histopathologic examination of the completely removed tumor revealed an epidermoid cyst. CONCLUSION: This unique case involved a patient with bilateral papilledema caused by a huge intracranial epidermoid cyst. Epidermoid tumors should be considered in the differential diagnosis of papilledema.

Adult↗
PubMed2000

Manual keratometry and videokeratography after photorefractive keratectomy.

PURPOSE: To examine the relative accuracy of manual keratometry and videokeratography in eyes treated by photorefractive keratectomy (PRK). SETTING: Eye Clinic, Cantonal Hospital, Lucerne, Switzerland. METHODS: Results of manual keratometry and videokeratography were compared with those of subjective refraction in 128 eyes before and 6 months after PRK. RESULTS: Six months after PRK, the mean subjective refraction of all eyes decreased more than the mean corneal dioptric power measured with videokeratography (P <.0001). The change in the mean subjective refraction compared with the corresponding difference in the mean manual keratometry of all eyes was also significant (P <.0001). CONCLUSIONS: This study confirmed an earlier observation that there is a disparity between the change in refraction and the reduction in corneal power measured by videokeratography and with the manual keratometer. Topographical changes from PRK and the subsequent wound-healing processes are likely to falsify objective measurements. The keratometric value in the center of the cornea, since it is not measured by manual keratometry and videokeratography, may actually be lower.

Adult↗
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↗
PubMed2000

[Vertical diplopia after cataract operation].

PURPOSE: Presentation and analysis of patients with vertical diplopia appearing after cataract surgery in retrobulbar anesthesia. SUBJECTS AND METHODS: Between 1990 and 1998 9 Patients with vertical diplopia following cataract surgery in retrobulbar anesthesia were studied in our Orthoptic Department. Each patient had complete orthoptic examination with Hess-screen-test. Additionally, some patients underwent neuroradiologic imaging and forced-duction testing. RESULTS: We subdivided the patients in a group of 4 patients with hypertropia and of 5 patients with hypotropia of the operated eye. All hypotropias were left-sided. Seven patients showed an overaction of the involved muscle without regression. Seven patients underwent surgery of a vertical muscle. Only 1 patient needed prismatic therapy postoperatively. The other 2 non-operated patients were satisfied with prisms alone. CONCLUSIONS: The proposed pathogenesis of vertical diplopia in these cases is fibrosis and contracture of the injured muscle, which could be due to anesthetic myotoxicity after direct injection into the muscle or to an intramuscular hemorrhage. On the other hand hypertropia could be a result of placement of bridle sutures. We discuss prevention and therapy of such complications.

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↗
PubMed1998

Lack of correlation between maximum early follicular phase serum follicle stimulating hormone concentrations and menstrual cycle characteristics in women under the age of 35 years.

The gradual increase in follicle stimulating hormone (FSH) concentrations in women approaching menopause results from the depletion of the ovarian follicular pool, a process referred to as 'ovarian ageing'. This study investigates whether variable endogenous FSH concentrations, as have been observed in normo-ovulatory young women, are related to menstrual cycle characteristics, including predictors of ovarian ageing. Serum concentrations of immunoreactive FSH, oestradiol, and inhibin-A and inhibin-B were measured, and follicular growth was assessed by transvaginal ultrasound throughout the follicular phase in 39 healthy volunteers (20-35 years) with regular menstrual cycles. Median serum FSH concentration on cycle day 3 was 5.1 IU/l (range 3.6-11.2), and median maximum follicular phase FSH was 6.2 IU/l (range 4.3-11.2), observed on cycle day 6 (range 2-15). Maximum FSH concentrations were not correlated with age or cycle length, nor with maximum inhibin-B. The number of small (<10 mm) antral follicles on cycle day 3 was 11 (range 4-21) and was not correlated with age, nor with maximum FSH. Inhibin-A remained low until a significant rise on cycle day 9 (range 3-12), which was significantly correlated with the late follicular rise in oestradiol (r = 0.56, P = 0.01). These observations indicate a lack of correlation between maximum follicular phase serum FSH concentrations and parameters of ovarian ageing in women under the age of 35 years. In addition, FSH concentrations assessed on cycle day 3 represent an underestimation of maximum early follicular phase FSH. Distinct individual differences in intra-ovarian modification of FSH action, resulting in differences in the FSH threshold for stimulation of ovarian function, may be operative.

Adult↗
PubMed1998

Confocal microscopy reveals persisting stromal changes after myopic photorefractive keratectomy in zero haze corneas.

AIMS: Micromorphological examination of the central cornea in myopic patients 8-43 months after excimer laser photorefractive keratectomy (PRK), using the slit scanning confocal microscope. METHODS: Patients were selected from a larger cohort of individuals on the basis of full corneal clarity (haze grading 0 to +1; mean 0.3) and their willingness to participate in the study. 15 eyes of 10 patients with myopic PRK (-4 to -11 D; mean 6.7) and an uneventful postoperative interval of 8-43 months (mean 26) were examined. Contact lenses had been worn by eight of the 10 patients for 4-11 years (mean 6.7) before surgery. Controls included the five untreated fellow eyes of PRK patients, 10 healthy, age matched volunteers without a history of ocular inflammation or contact lens wear, and 20 patients who had worn rigid gas permeable (n = 10) or soft contact lenses (n = 10) for 2-11 years. Subjects were examined with a real time flying slit, scanning confocal microscope using x25 and x50 objectives. RESULTS: In PRK treated patients and contact lens wearers, basal layer epithelial cells sporadically displayed enhanced reflectivity. The subepithelial nerve plexus was observed in all individuals, but was usually less well contrasted in the PRK group, owing to the presence of a very discrete layer of subepithelial scar tissue, which patchily enhanced background reflectivity. Within all layers of the stroma, two distinct types of abnormal reflective bodies were observed in all PRK treated eyes, but in none of the controls. One had the appearance of long (> = 50 microns), slender (2-8 microns in diameter) dimly reflective rods, which sometimes contained bright, punctate, crystal-like inclusions, arranged linearly and at irregular intervals. The other was shorter (< 25 microns), more slender in form (< 1 micron in diameter), and highly reflective; these so called needles were composed of crystal-like granules in linear array, with an individual appearance similar to the bright punctate inclusions seen in rods, but densely packed. Both of these unusual structures were confined, laterally, to the ablated area, but were otherwise distributed throughout all stromal layers, with a clear predominance in the anterior ones. These rods and needles were observed in all PRK treated corneas, irrespective of previous contact lens wear. On the basis of qualitative inspection, the incidence of rods and needles did not appear to correlate with either the volume of tissue ablated or the length of the postoperative interval. In contact lens wearing controls, highly reflective granules, reminiscent of those from which the needles were composed, were found scattered as isolated entities throughout the entire depth and lateral extent of the corneal stroma, but rods and needles were never encountered. The corneal endothelium exhibited no obvious abnormalities. CONCLUSION: Confocal microscopy 8-43 months after PRK revealed belated changes in the corneal stroma. These were manifested as two distinct types of abnormal reflective bodies, which had persisted beyond the stage when acute wound healing would have been expected to be complete. The clinical significance of these findings in the context of contrast visual acuity and long term status of the cornea is, as yet, unknown.

Adult↗
PubMed1998

The follicle-stimulating hormone (FSH) threshold/window concept examined by different interventions with exogenous FSH during the follicular phase of the normal menstrual cycle: duration, rather than magnitude, of FSH increase affects follicle development.

According to the threshold concept, FSH concentrations need to surpass a distinct level to stimulate ovarian follicle growth. The window concept stresses the significance of a limited duration of elevated FSH levels above the threshold for single dominant follicle selection. The aim of this study was to investigate effects on follicle growth of increased FSH levels, differing in duration and magnitude of elevation, during the follicular phase. Twenty-three normo-ovulatory (cycle length, 26-31 days), young (age, 20-31 yr) women volunteered for this study. In all subjects a series of daily transvaginal sonography scans of the ovaries and blood sampling [for FSH and estradiol (E2) determinations] were performed during two consecutive cycles. The first study cycle (control cycle) started 10 days after urinary assessment of the LH surge in the preceding cycle (DayLH) and was concluded on the day of ovulation assessed by transvaginal sonography scans. The second series of daily monitoring (intervention cycle) started 10 days after DayLH in the control cycle. After randomization, subjects received either 375 IU urinary FSH, s.c., as a single injection on Day(LH+14) (group A; n = 11) or 75 IU daily from Day(LH+19) until Day(LH+23) (group B; n = 12). In group A, FSH levels increased on the day after injection to a median concentration of 10.1 IU/L, which was 1.9 times higher (P < 0.01) than levels on matching days during the control cycle. Concentrations returned to basal levels 3 days after injection. In group B, a moderate elevation of FSH concentrations (15% increase; P < 0.05) was observed compared to levels during the control cycle. In group A, E2 concentrations increased (P = 0.03) 1 day after FSH injection and returned to baseline levels within 2 days. In group B, E2 levels started to increase after the first injection of FSH and remained significantly higher (P < 0.01) during the following 5 days compared to those on matching days in the control cycle. Compared to matching days in the control cycle an increased number of follicles 8-10 mm in size was found in group A (P < 0.01) during the period from Day(LH+14) until Day(LH+19), without an increase in follicles 10 mm or larger thereafter. In contrast, in group B, the numbers of both 8- to 10-mm and 10-mm or larger follicles were higher during the period from Day(LH+19) until Day(LH+24) in group B (P = 0.02 and P < 0.01, respectively). Results from the present study suggest that a brief, but distinct, elevation of FSH levels above the threshold in the early follicular phase does not affect dominant follicle development, although the number of small antral follicles did increase. In contrast, a moderate, but continued, elevation of FSH levels during the mid to late follicular phase (effectively preventing decremental FSH concentrations) does interfere with single dominant follicle selection and induces ongoing growth of multiple follicles. These findings substantiate the FSH window concept and support the idea of enhanced sensitivity of more mature follicles for stimulation by FSH. These results may provide the basis for further investigation regarding ovulation induction treatment regimens with reduced complication rates due to overstimulation.

Adult↗