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Biomedical subjects

H Gerding

Publications and source records attributed to H Gerding.

At least 19 recordsLinked to original sources
PubMed2004

[Perfluorohexyloctane as internal tamponade in patients with complicated retinal detachment. Results after 6 months].

BACKGROUND: Perfluorohexyloctane (F6H8) is the first medium that can be transiently used as postoperative heavy vitreous substitute expanding the technique of intraocular tamponade by the principle of an inferiorly acting medium. Legally it can be used for up to 3 months. So far very few clinical reports are available on the efficacy and possible complications of F6H8. It was the aim to analyze this in a group of patients with retinal redetachment after one or several previous retinal/vitreoretinal interventions. PATIENTS AND METHODS: This study included 17 patients (10 male, 7 female, median age 66 years, range 34-88 years) with a complicated retinal redetachment (at least inferior quadrants). Median duration of intraocular F6H8 use was 25 days. Follow-up was limited to 6 months. RESULTS: Primary retinal reattachment could be achieved in 16/17 eyes. 8/17 developed retinal redetachment during follow-up. After additional surgery 12/17 presented complete retinal attachment, 4/17 subtotal attachment and 1/17 total retinal detachment. The latter was enucleated as a consequence of several further complications such as chronic hypotony, severe keratopathy and painful atrophy. The spectrum of complications during and after F6H8 tamponade included dispersion 17/17 (10/17 clinical, 7/17 minor), hypotony (endpoint) 14/17, massive cell precipitation on lens/IOL or in the anterior segment 7/17, severe progression of capsular fibrosis (8/17), and keratopathy 6/17. CONCLUSIONS: The spectrum of postoperative complications after F6H8 use, especially the high proportion of eyes with chronic hypotony, indicates that F6H8 may not be a recommendable option in eyes with a complicated surgical history.

Adult↗
PubMed2004

Illuminated artificial orbit for the training of vitreoretinal surgery in vitro.

PURPOSE: Demonstrations and practical experiments are important constituents of the teaching of surgical principles and techniques to residents in ophthalmology. The objective was to develop an eye-support device for experimental and didactic use during vitreoretinal microsurgery in vitro. METHODS: Various eye-support devices with different light sources and illumination intensities were designed and tested. The main components of the final prototype are a high-intensity halogen lamp, a flexible light guide, a cylinder with a mirror inside, and a replaceable, transparent eye support with a ring-adapter. Light from the point source is reflected via the light guide into the cylinder and through the eye support transsclerally into the eye. RESULTS: The device illuminates the retina and the vitreous body sufficiently. It accentuates the transparent appearance of the retina and makes the three-dimensional structure more visible, for example, in case of retinal detachment. Subretinal tissue can be visualized and differentiated more precisely. CONCLUSIONS: The device is useful, in the teaching of residents and in experimental vitreoretinal surgery.

Animals↗
PubMed2003

Phantom eye syndrome: Its prevalence, phenomenology, and putative mechanisms.

This study presents data on the clinical characteristics and possible mechanisms of the phantom eye syndrome in 112 patients after removal of one eye. The prevalence of phantom eye pain was 26%, nonpainful phantom sensations 29%, and visual hallucinations 31%. Headaches and preoperative eye pain were associated with the presence of phantom experiences. These results suggest that pain is an important cofactor for the development of phantom eye phenomena.

Adult↗
PubMed2003

[Phantom pain after eye enucleation].

BACKGROUND: Phantom pain is a well known and extensively documented complication after limb amputation. Nearly all surgical disciplines have to deal with phantom symptoms related to different anatomical regions and organs but limited data is available about phantom eye pain (PEP) after enucleation. Only one pilot study is present in literature. It was the aim of this study to analyze a group of patients with a standardized surgical procedure of enucleation concerning the incidence of PEP and its relation to further preoperative and postoperative data. PATIENTS AND METHODS: A standardized questionnaire was sent to all enucleation patients with primary orbital implant performed between 1/1/1986 and 12/31/1995 at Münster University. Data of 94 patients could be analyzed with regard to PEP, perioperative pain symptoms and further ophthalmological and surgical data. RESULTS: 24 of 94 patients reported PEP after enucleation. The frequency of PEP was less than once per month in the majority of patients (71%). 2 of 24 patients suffered from PEP on more than 4 days/month. Perioperative pain symptoms (ocular pain [OP], preoperative and postoperative headache) were reported with a higher proportion (each p<0.0025) in patients with PEP compared to those not affected by PEP. All patients with a preoperative history of OP longer than 5 years and 75% of patients with OP longer than 12 months of pre-enucleation OP were affected by PEP. CONCLUSIONS: Phantom eye pain is present in nearly 1/4 of patients after enucleation and is significantly related to other perioperative pain symptoms.

Adult↗
PubMed2001

[Electrical stimulation of the visual system. From empirical approach to visual prostheses].

The investigation of the influence of electrical stimulation on the visual system can be sub-divided into empirical, diagnostic and therapeutic phases of development. The first electrical stimulations of the visual system in animals dating back to the eighteenth century represent empirical approaches well before knowledge on the principles of bioelectrical nerve activity was available. Despite this lack of understanding, attempts were made at that time to treat blind people by electrical stimulation. More than 100 years later, with the advancement of technology and knowledge on nerve function, attempts were made to establish various methods of electrical stimulation for the diagnosis of different diseases of the visual system. For more than 30 years attempts to develop electrical devices have been made to by-pass defects of the visual system and to restore basic orientation. Presently nine different groups world-wide are focusing on retinal, optic or cortical implants. A short review on the historical use of electrical stimulation and new therapeutical attempts are given in this paper.

Action Potentials↗
PubMed1998

Expression of the gene for the retinal protein peripherin in the pineal gland of humans and Djungarian hamsters (Phodopus sungorus).

This study investigated whether the gene for peripherin, a protein previously considered to play only a role in the retina, may also be expressed in the pineal gland of both Djungarian hamsters (Phodopus sungorus) and humans. After extraction of mRNA from pooled pineal glands of hamsters and from one human pineal gland, mRNA was transcribed into cDNA followed by PCR amplification with specific primers. Clear signals were obtained at the expected sizes of the PCR products. An additional experiment in hamsters revealed that the peripherin gene is expressed throughout the entire 24-h period. Since peripherin is an important protein in the retina stabilizing the photoreceptor discs it is speculated that this protein might also play a structural role in the pineal gland.

Animals↗
PubMed1998

Ocular complications and a new surgical approach to lens dislocation in homocystinuria due to cystathionine-beta-synthetase deficiency.

The ocular findings in patients with homocystinuria due to cystathionine-beta-synthetase (CBS) deficiency are reviewed and a new approach to lens surgery is presented. Lens surgery in CBS deficiency was reported to be accompanied by a high risk of secondary complications like vitreal prolapse and retinal detachment. So far an operative procedure for these patients that allows a complete preservation of the anterior vitreous cortex, the posterior lens capsule and an implantation of an artificial lens is not established. A minimal invasive method of lens surgery was developed in vitro and applied in the case of a 10-year-old patient with an uncorrectable refractive situation due to progressed lens dislocation. Principle steps of the evolved operative procedure are (1) visco-elastic stabilization of the anterior chamber; (2) small (1.5 mm) peripheral capsulorhexis; (3) manual endocapsular aspiration of lens material and removal of lens epithelium; (4) ab externo introduction of a transcleral fixation suture; (5) positioning of the haptic into the ciliary sulcus in the inferior position; (6) resection of the anterior lens capsule; and (7) positioning of the second haptic into the ciliary sulcus. The first patient treated according to this method presented a stable position of the pseudophakos during the follow up of 1 year. Visual acuity improved from a level of 20/200 (O.D.) and 10/200 (O.S.) to 18/20 in both eyes. The surgical procedure presented in this report seems to be useful for dealing with dislocated lenses due to zonular deficiency in patients with CBS deficiency and hopefully with Marfan disease. It allows a minimal invasive removal of the lens, a complete preservation of the anterior vitreous cortex and at the same time a stable fixation of an artificial intraocular lens.

Child↗
PubMed1998

[Intraocular lens implantation in childhood. Functional results and complications].

UNLABELLED: IOL implantation in childhood is still controversial. INTENTION: The purpose of this retrospective study was to evaluate functional results and complications in children after IOL implantation. METHODS AND RESULTS: Posterior chamber IOLs were implanted in 52 eyes of 45 children. Cataract extraction was necessary because of traumatic, congenital/developmental and secondary lens opacities. Nine IOLs were implanted in children between the ages of 1.9 and 4 years, 17 IOLs from 4 to 8 years and 26 IOLs in patients 8 to 14.3 years old. In 38 of the 52 eyes (73%) vision improved after the surgery. Fifty-four percent had an acuity of at least 0.5. The functional results of children more than 8 years old were superior to those of younger patients. Children with traumatic cataracts had better visual acuities than those with other types of cataract. Except for secondary capsular opacities (75%) that could not be prevented by performing a primary posterior capsulotomy or capsulectomy and iris capture (31%), postoperative complications were rare. CONCLUSION: Favorable functional results can be achieved by IOL implantation in children with cataracts. Many patients require secondary surgical procedures because of capsular opacities and iris capture.

Adolescent↗
PubMed1998

A dummy orbit for training in diagnostic procedures and laser surgery with enucleated eyes.

PURPOSE: A dummy orbit for enucleated eyes was developed for training residents in diagnostic and surgical procedures. METHODS: Porcine eyes were used to construct the model. The device is made of black anodized metal. The final prototype was tested for ease of use and optical quality. Principal elements are an adjustable eye support, a cylinder, and a removable ring. RESULTS: The dummy orbit and enucleated eye allow direct and indirect ophthalmoscopy; inspection with contact lenses, including gonioscopy; and retinal laser coagulation using contact lenses. Laser trabeculoplasty, argon laser trabeculotomy, Nd:YAG laser iridectomy, and Nd:YAG laser capsulectomy are possible, as well as training in tonometry and ultrasonography techniques. CONCLUSION: The dummy orbit is a valuable aid for teaching and training in diagnostic and laser surgery procedures with nondissected enucleated eyes.

Animals↗
PubMed1997

[Effect of locally applied lidocaine on expression of the oculocardiac reflex].

INTRODUCTION: The oculocardiac reflex causes severe bradycardic arrhythmias and is a frequent complication during surgical manipulation at the medial rectus muscle. The purpose of this study was to evaluate the influence of lidocaine administered topically on the muscle on the incidence of the oculocardiac reflex. PATIENTS AND METHODS: After obtaining informed consent, 140 patients with strabism or retinal surgery were included in this study. All patients received standard premedication and anesthesia and were randomly assigned to two groups. Patients (n = 70) randomly assigned to the first group received 1 mg/kg lidocaine applied topically to the muscle after opening the conjunctiva. Individuals in the placebo group received the same volume of saline (0.9%). Surgical stimulation occurred 5 min after administration of the drug. The study parameters (blood pressure/heart rate) were recorded before and after stimulation of the oculocardiac reflex caused by routine surgical preparation. RESULTS: Topical administration of lidocaine reduced the incidence of the oculocardiac reflex (86.1% vs 37.1%), and the frequency of severe bradycardiac arrhythmias was also significantly reduced (40 vs. 2.9%). Cardiac arrest for longer than 10 s did not occur in the lidocaine group. In the control group this phenomenon was observed in 14.8%.

Adolescent↗
PubMed1997

[Keratoprosthesis for experimental surgical use of donor eyes after corneal removal].

BACKGROUND: Keratoprosthetic devices have been introduced for short-term use during surgical interventions and for long-term therapeutical use. The keratoprosthesis presented here was developed for the experimental use of human donor eyes after removal of the cornea. MATERIALS AND METHODS: In a step-by-step modification process, the main constructive elements of the keratoprosthesis were modified and tested for handling, operative stability and optical quality. PMMA was used as basic material. RESULTS: The final model was a two-piece device consisting of a screw (8.0 mm long, 14.5 mm in diameter) with an ample base (17.5 mm in diameter) for the introduction into the anterior segment following a corneal removal 15.0 mm in diameter. A threaded outer ring fixes the scleral rim against the screw. Lateral boreholes enable the devices to be handled by ordinary surgical forceps. CONCLUSIONS: The keratoprosthesis proved to be a useful and efficient aid in experimental and nearly realistic vitreoretinal surgery with human donor eyes after removal of the cornea.

Corneal Transplantation↗