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1.
J Hosp Infect ; 116: 16-20, 2021 Oct.
Article in English | MEDLINE | ID: mdl-34144097

ABSTRACT

Besides conventional prevention measures, no-touch technologies based on gaseous systems have been introduced in hospital hygiene for room disinfection. The whole-room disinfectant device Sterisafe Pro, which creates ozone as a biocidal agent, was tested for its virucidal efficacy based on Association Française de Normalisation Standard NF T 72-281:2014. All test virus titres were reduced after 150 and 300 min of decontamination, with mean reduction factors ranging from 2.63 (murine norovirus) to 3.94 (simian virus 40). These results will help to establish realistic conditions for virus inactivation, and assessment of the efficacy of ozone technology against non-enveloped and enveloped viruses.


Subject(s)
Disinfectants , Ozone , Animals , Disinfectants/pharmacology , Disinfection , Humans , Hygiene , Mice , Ozone/pharmacology , Virus Inactivation
2.
J Hosp Infect ; 112: 27-30, 2021 Jun.
Article in English | MEDLINE | ID: mdl-33771601

ABSTRACT

In the ongoing SARS CoV-2 pandemic, effective disinfection measures are needed, and guidance based on the methodological framework of the European Committee for Standardization (CEN) may enable the choice of effective disinfectants on an immediate basis. This study aimed to elucidate whether disinfectants claiming 'virucidal activity against enveloped viruses' as specified in the European Standard EN 14476 as well as in the German Association for the Control of Viral Diseases/Robert Koch Institute (DVV/RKI) guideline are effectively inactivating SARS-CoV-2. Two commercially available formulations for surface disinfection and one formulation for hand disinfection were studied regarding their virucidal activity. Based on the data of this study the enveloped SARS-CoV-2 is at least equally susceptible compared to the standard test virus vaccinia used in the EN 14476 and DVV/RKI guidelines. Thus, chemical disinfectants claiming 'virucidal activity against enveloped viruses' based on the EN 14476 and DVV/RKI guidelines will be an effective choice to target enveloped SARS-CoV-2 as a preventive measure.


Subject(s)
Antiviral Agents/pharmacology , Disinfectants/pharmacology , Disinfection/standards , Hand Disinfection/standards , SARS-CoV-2/drug effects , Antiviral Agents/chemistry , COVID-19/prevention & control , Disinfectants/chemistry , Disinfection/classification , Hand Disinfection/methods , Humans , Virus Diseases/prevention & control
3.
J Hosp Infect ; 111: 180-183, 2021 May.
Article in English | MEDLINE | ID: mdl-33582201

ABSTRACT

The outbreak of the SARS-CoV-2 pandemic is triggering a global health emergency alert. Until vaccination becomes available, a bundle of effective preventive measures is desperately needed. Recent research is indicating the relevance of aerosols in the spread of SARS-CoV-2. Thus, in this study commercially available antiseptic mouthwashes based on the active ingredients chlorhexidine digluconate and octenidine dihydrochloride (OCT) were investigated regarding their efficacy against SARS-CoV-2 using the European Standard 14476. Based on the requirement of EN 14476 in which reduction of at least four decimal logarithms (≥4 log10) of viral titre is requested to state efficacy, the OCT-based formulation was found to be effective within a contact time of only 15 s against SARS-CoV-2. Based on this in-vitro data the OCT mouthwash thus constitutes an interesting candidate for future clinical studies to prove its effectiveness in a potential prevention of SARS-CoV-2 transmission by aerosols.


Subject(s)
Anti-Infective Agents, Local/standards , Antiviral Agents/pharmacology , Antiviral Agents/standards , COVID-19/prevention & control , Chlorhexidine/pharmacology , Chlorhexidine/standards , Mouthwashes/standards , Anti-Infective Agents, Local/pharmacology , Humans , Pandemics , Reference Standards , SARS-CoV-2
4.
Gait Posture ; 68: 264-268, 2019 02.
Article in English | MEDLINE | ID: mdl-30551051

ABSTRACT

BACKGROUND: Gait speed tests are useful predictors of different health outcomes in people. These tests can be administered by the convenience of one's smartphone. RESEARCH QUESTION: Is the 6th Vital Sign app valid and reliable for measuring gait speed? METHODS: The study used a prospective test-retest design. Fifteen college subjects were asked to walk at their normal pace for 2 min. Each subject performed two trials. Speed was recorded by the 6th Vital Sign app, Brower timing gates, and by hand-measurement of distance walked divided by the 2 min. Criterion validity was assessed by paired t-tests, Cohen's D effect sizes, and Pearson correlation tests. Inter-trial reliability within each device was assessed with Pearson correlation tests. RESULTS: Speed measured by the app was significantly lower than speed measured by gates (p = 0.004) and by hand-measurement (p = 0.009). The difference between gates and hand-measurement was not significant (p = 0.684). The speed measured by gates and hand-measurement were very highly correlated (r = 0.974), but speed measured by app was only moderately correlated with gates (r = 0.370) and hand-measurement (r = 0.365). The inter-trial reliability was fairly high with correlations r = 0.916, 0.944, and 0.941 when speed was measured by the app, gates, and hand-measurement, respectively. SIGNIFICANCE: The app tended to underestimate speed when compared to gate and hand-measurements. Therefore, we conclude that the 6th Vital Sign app is not valid for use for clinical diagnosis or prognosis.


Subject(s)
Gait/physiology , Mobile Applications/standards , Outcome Assessment, Health Care/methods , Physical Fitness/physiology , Smartphone , Walking Speed/physiology , Adult , Female , Humans , Male , Middle Aged , Prospective Studies , Reproducibility of Results
6.
Biomed Res Int ; 2014: 217078, 2014.
Article in English | MEDLINE | ID: mdl-25013767

ABSTRACT

Resorbable polymeric implants and surface coatings are an emerging technology to treat bone defects and increase bone formation. This approach is of special interest in anatomical regions like the calvaria since adults lose the capacity to heal large calvarial defects. The present study assesses the potential of extracellular matrix inspired, embroidered polycaprolactone-co-lactide (PCL) scaffolds for the treatment of 13 mm full thickness calvarial bone defects in rabbits. Moreover the influence of a collagen/chondroitin sulfate (coll I/cs) coating of PCL scaffolds was evaluated. Defect areas filled with autologous bone and empty defects served as reference. The healing process was monitored over 6 months by combining a novel ultrasonographic method, radiographic imaging, biomechanical testing, and histology. The PCL coll I/cs treated group reached 68% new bone volume compared to the autologous group (100%) and the biomechanical stability of the defect area was similar to that of the gold standard. Histological investigations revealed a significantly more homogenous bone distribution over the whole defect area in the PCL coll I/cs group compared to the noncoated group. The bioactive, coll I/cs coated, highly porous, 3-dimensional PCL scaffold acted as a guide rail for new skull bone formation along and into the implant.


Subject(s)
Absorbable Implants , Bone Regeneration/drug effects , Osteogenesis/drug effects , Skull/growth & development , Tissue Engineering , Animals , Extracellular Matrix/metabolism , Extracellular Matrix/pathology , Humans , Polyesters/chemistry , Polyesters/therapeutic use , Rabbits , Skull/drug effects , Tissue Scaffolds , Wound Healing
7.
Internist (Berl) ; 54(7): 810-7, 2013 Jul.
Article in German | MEDLINE | ID: mdl-23736958

ABSTRACT

Due to continuous technical developments computed tomography (CT) is increasingly being used for cardiac diagnostics, especially for diagnosis of coronary artery disease (CAD) or less commonly for evaluation of coronary artery anomalies, cardiac valves or cardiac function. Because CT exposes patients to ionizing radiation it should only be performed in patients with a clear indication. Calcium scoring for example may improve risk stratification in asymptomatic patients with an intermediate risk profile or coronary CT angiography may be used to exclude or confirm obstructive CAD in symptomatic patients at intermediate cardiovascular risk. However, other patients, such as symptomatic patients with high cardiovascular risk should not be examined using CT. Therefore, a reasonable use of CT in cardiology requires a differentiated selection of patients.


Subject(s)
Calcinosis/complications , Calcinosis/diagnostic imaging , Coronary Angiography/methods , Coronary Artery Disease/diagnostic imaging , Coronary Artery Disease/etiology , Radiographic Image Enhancement/methods , Tomography, X-Ray Computed/methods , Humans
8.
J Hosp Infect ; 82(4): 277-80, 2012 Dec.
Article in English | MEDLINE | ID: mdl-23009803

ABSTRACT

Three ethanol-based sanitizers were compared with three antimicrobial liquid soaps for their efficacy to inactivate polio-, adeno-, vaccinia- and bovine viral diarrhoea virus (BVDV) as well as feline calicivirus (FCV) and murine norovirus (MNV) as surrogates for human norovirus in a suspension test. Additionally, sanitizers and soaps were examined against MNV in a modified fingerpad method. All sanitizers sufficiently inactivated the test viruses in the suspension test whereas two soaps were active only against vaccinia virus and BVDV. In the modified fingerpad test a povidone-iodine-containing soap was superior to the sanitizers whereas the other two soaps showed no activity.


Subject(s)
Antiviral Agents/administration & dosage , Disinfectants/administration & dosage , Hand Disinfection/methods , Viruses/drug effects , Alcohols/administration & dosage , Humans , Microbial Viability/drug effects , Soaps/administration & dosage
10.
J Microbiol Methods ; 74(1): 10-6, 2008 Jul.
Article in English | MEDLINE | ID: mdl-17884208

ABSTRACT

Robust filtering techniques capable of efficiently removing particulates and biological agents from water or air suffer from plugging, poor rejuvenation, low permeance, and high backpressure. Operational characteristics of pressure-driven separations are in part controlled by the membrane pore size, charge of particulates, transmembrane pressure and the requirement for sufficient water flux to overcome fouling. With long term use filters decline in permeance due to filter-cake plugging of pores, fouling, or filter deterioration. Though metallic filter tube development at ORNL has focused almost exclusively on gas separations, a small study examined the applicability of these membranes for tangential filtering of aqueous suspensions of bacterial-sized particles. A mixture of fluorescent polystyrene microspheres ranging in size from 0.5 to 6 microm in diameter simulated microorganisms in filtration studies. Compared to a commercial filter, the ORNL 0.6 microm filter averaged approximately 10-fold greater filtration efficiency of the small particles, several-fold greater permeance after considerable use and it returned to approximately 85% of the initial flow upon backflushing versus 30% for the commercial filter. After filtering several liters of the particle-containing suspension, the ORNL composite filter still exhibited greater than 50% of its initial permeance while the commercial filter had decreased to less than 20%. When considering a greater filtration efficiency, greater permeance per unit mass, greater percentage of rejuvenation upon backflushing (up to 3-fold), and likely greater performance with extended use, the ORNL 0.6 microm filters can potentially outperform the commercial filter by factors of 100-1,000 fold.


Subject(s)
Filtration/methods , Micropore Filters , Water Purification , Metals , Micropore Filters/standards , Particle Size , Water Purification/methods
11.
J Neurol Neurosurg Psychiatry ; 79(2): 170-5, 2008 Feb.
Article in English | MEDLINE | ID: mdl-17578855

ABSTRACT

OBJECTIVE: In vestibular schwannoma surgery, four different intraoperative brainstem auditory evoked potential (BAEP) patterns (stable BAEP, abrupt loss, irreversible progressive loss, reversible loss) can be identified and correlated with postoperative hearing outcome. Patients with reversible loss significantly benefit from postoperative vasoactive treatment consisting of hydroxyethyl starch and nimodipine. The present study investigates the treatment effect in the remaining three BAEP patterns. METHODS: A retrospective analysis was performed in 92 patients operated on for vestibular schwannoma between 1997 and 2005. Between 1997 and 2001, only patients with reversible loss of BAEP received vasoactive medication. Subsequently, all patients operated on between 2001 and 2005 received a 10 day course of therapy, regardless of the BAEP pattern. Serial audiological examinations before, after surgery and after 1 year were performed in all patients. RESULTS: All 30 patients with reversible loss of BAEP received medication, and postoperative hearing preservation was documented in 21 patients. All 13 patients with stable waves showed hearing preservation, regardless of treatment. In all 24 patients with abrupt loss and in all 25 patients with irreversible progressive loss, postoperative anacusis was documented, regardless of treatment. CONCLUSION: In patients with reversible loss of BAEP, a disturbed microcirculation of the cochlear nerve seems to be the underlying pathophysiological factor. In patients with abrupt or irreversible progressive loss, additional mechanical injury of nerve fibres determines hearing outcome. The study provides evidence that for the purpose of hearing preservation, only patients with reversible loss of BAEP benefit from vasoactive treatment.


Subject(s)
Evoked Potentials, Auditory, Brain Stem/physiology , Hearing/physiology , Monitoring, Intraoperative , Neuroma, Acoustic/surgery , Vasodilator Agents/therapeutic use , Adult , Brain Stem/physiopathology , Cochlear Nerve/blood supply , Cochlear Nerve/injuries , Deafness/drug therapy , Deafness/physiopathology , Female , Follow-Up Studies , Hearing Loss, Sensorineural/drug therapy , Hearing Loss, Sensorineural/physiopathology , Humans , Hydroxyethyl Starch Derivatives/therapeutic use , Ischemia/drug therapy , Ischemia/physiopathology , Male , Microcirculation/physiopathology , Middle Aged , Neuroma, Acoustic/physiopathology , Nimodipine/therapeutic use , Postoperative Complications/drug therapy , Postoperative Complications/physiopathology , Retrospective Studies
12.
Clin Res Cardiol ; 95(8): 405-12, 2006 Aug.
Article in English | MEDLINE | ID: mdl-16799879

ABSTRACT

AIMS: The DETECT study was performed to obtain representative data about the frequency, distribution, and treatment of patients with coronary artery disease (CAD) in the primary care setting in Germany. METHODS AND RESULTS: The DETECT study was a cross-sectional clinical- epidemiological survey of a nationally representative sample of 3795 primary care offices and 55,518 patients. Overall, 12.4% of patients were diagnosed with CAD. Stable angina pectoris and myocardial infarction were the most frequent (4.2%) subgroups, followed by status post (s/p) percutaneous coronary interventions (PCI, 3.0%) and s/p coronary bypass surgery (2.2%). Patients with CAD were prescribed AT1 receptor antagonists (in 19.4% of cases), beta blockers (57.2%), ACE inhibitors (49.9%), antiplatelet agents (52.7%), statins (43.0%), and long-term nitrates (24.5%). When comparing all CAD patients with social health care insurance to those who had private insurance, private patients had significantly higher rates of revascularisation procedures and use of preventive medications. CONCLUSION: Great potential remains for improving secondary prevention in primary care in Germany to reduce the risk of further coronary or vascular events, especially in patients with social health care insurance.


Subject(s)
Cardiovascular Agents/therapeutic use , Coronary Disease/epidemiology , Myocardial Revascularization/statistics & numerical data , Outcome Assessment, Health Care/methods , Physicians, Family , Adolescent , Adult , Aged , Coronary Disease/prevention & control , Cross-Sectional Studies , Female , Follow-Up Studies , Germany/epidemiology , Humans , Male , Middle Aged , Prevalence , Prospective Studies
13.
J Safety Res ; 35(1): 91-106, 2004.
Article in English | MEDLINE | ID: mdl-14992850

ABSTRACT

PROBLEM: Exclusive reliance on such practices as policy review, audiometric testing audits, and noise surveillance to evaluate the effectiveness of workplace hearing conservation programs (HCP) fails to capture the impact of these programs as experienced by workers at the "shop floor" and offers little insight into the reasons and potential remedies for noted deficiencies. METHODS: A qualitative approach for evaluating industrial HCPs (and their various components) is discussed using three industrial populations as case studies. For each study population, this paper illustrates how focus groups, comprised of line workers and supervisors, were used to clarify and augment information gathered through more traditional program assessments to provide a more enriched picture of hearing conservation practices. Descriptive data on plant hearing conservation program practices at each plant are presented with a comparison of proactive elements of each program relative to the Occupational Safety and Health Administration (OSHA) Hearing Conservation Amendment (HCA) requirement and to internal plant policy. RESULTS: Yearly program evaluation with input from all end-users is important in the process of hearing loss prevention. The qualitative assessment outlined in this paper serves as a basis for future quantitative assessments of HCP effectiveness using hearing threshold data and noise exposure assessments to examine changes in hearing levels as a function of noise exposure and other risk factors for hearing loss.


Subject(s)
Focus Groups , Hearing Loss, Noise-Induced/prevention & control , Noise, Occupational/prevention & control , Occupational Diseases/prevention & control , Adult , Aged , Audiometry , Ear Protective Devices , Environmental Monitoring , Female , Guideline Adherence , Humans , Male , Middle Aged , National Institute for Occupational Safety and Health, U.S. , Program Evaluation , United States , United States Occupational Safety and Health Administration
14.
J Neurosurg ; 95(5): 771-7, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11702866

ABSTRACT

OBJECT: Delayed hearing loss following surgery for acoustic neuroma indicates anatomical and functional preservation of the cochlear nerve and implies that a pathophysiological mechanism is initiated during surgery and continues thereafter. Intraoperative brainstem auditory evoked potentials (BAEPs) typically demonstrate gradual reversible loss of components in these patients. METHODS: Based on this BAEP pattern, a consecutive series of 41 patients with unilateral acoustic neuromas was recruited into a prospective randomized study to investigate hearing outcomes following the natural postoperative course and recuperation after vasoactive medication. Both groups were comparable in patient age, tumor size, and preoperative hearing level. Twenty patients did not receive postoperative medical treatment. In 70% of these patients anacusis was documented and in 30% hearing was preserved. Twenty-one patients were treated with hydroxyethyl starch and nimodipine for an average of 9 days. In 66.6% of these patients hearing was preserved and in 33.3% anacusis occurred. CONCLUSIONS: These results are statistically significant (p < 0.05, chi2 = 5.51) and provide evidence that these surgically treated patients suffer from a disturbed microcirculation that causes delayed hearing loss following removal of acoustic neuromas.


Subject(s)
Hearing , Hydroxyethyl Starch Derivatives/therapeutic use , Neuroma, Acoustic/drug therapy , Neuroma, Acoustic/surgery , Nimodipine/therapeutic use , Plasma Substitutes/therapeutic use , Postoperative Care , Vasodilator Agents/therapeutic use , Adult , Aged , Deafness/etiology , Evoked Potentials, Auditory, Brain Stem , Humans , Middle Aged , Neuroma, Acoustic/physiopathology , Postoperative Complications , Postoperative Period , Prospective Studies , Treatment Outcome
15.
Neurosurgery ; 48(5): 1157-9; discussion 1159-61, 2001 May.
Article in English | MEDLINE | ID: mdl-11334285

ABSTRACT

IMPORTANCE: Preservation of venous drainage during surgery of the cerebellopontine angle has received little attention. CLINICAL PRESENTATION: We describe changes in brainstem auditory evoked potentials after temporary obstruction of the superior petrosal vein during surgical resection of a small meningioma at the petrous apex via a standard suboccipital-lateral approach. Temporary clipping of the petrosal vein resulted in deterioration of the brainstem auditory evoked potentials. The tumor was removed with preservation of the superior petrosal vein. CONCLUSION: A transient postoperative cochlear nerve deficit emphasizes the importance of venous drainage and its preservation during surgery for small lesions of the cerebellopontine angle that do not distort normal anatomic structures.


Subject(s)
Cerebellopontine Angle/surgery , Cochlear Nerve/physiopathology , Constriction , Evoked Potentials, Auditory, Brain Stem , Meningeal Neoplasms/surgery , Meningioma/surgery , Petrous Bone/blood supply , Female , Humans , Middle Aged , Postoperative Complications , Time Factors , Veins/physiopathology
16.
J Neurol Neurosurg Psychiatry ; 69(5): 679-82, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11032629

ABSTRACT

Contralateral hearing loss after surgical procedures within the cerebellopontine angle is rarely seen and its pathophysiological background is not yet understood. A patient with contralateral hearing loss after microvascular decompression for trigeminal neuralgia is described. Ipsilateral brainstem auditory potential (BAEP) monitoring and facial nerve EMG did not show major abnormalities. During otherwise uneventful and successful surgery a branch of the petrosal vein was sacrificed to widen the access to the trigeminal root exit zone. On the third postoperative day the patient complained about contralateral hearing loss, which was verified by audiometry. Contralateral BAEPs showed low amplitudes and delayed interpeak latencies. Brain CT was normal. Brain MRI on the 8th postoperative day disclosed abnormal signals within the ipsilateral inferior colliculus. Intravenous heparinisation was performed and hearing slowly recovered over a 3 month period. Results from this patient offer a pathophysiological mechanism for contralateral hearing loss after cerebellopontine angle surgery, illustrate the importance of venous drainage preservation, gives evidence about the generation of BAEP components within the contralateral brainstem, and stresses the importance of intraoperative BAEP monitoring.


Subject(s)
Deafness/physiopathology , Evoked Potentials, Auditory, Brain Stem/physiology , Inferior Colliculi/physiopathology , Neurosurgical Procedures/adverse effects , Trigeminal Neuralgia/surgery , Acoustic Stimulation , Female , Functional Laterality/physiology , Humans , Middle Aged , Reaction Time/physiology
17.
Clin Neurophysiol ; 110(11): 1935-41, 1999 Nov.
Article in English | MEDLINE | ID: mdl-10576490

ABSTRACT

Based on a consecutive series of 70 hearing patients with unilateral acoustic neurinomas and intraoperative monitoring of brain-stem auditory evoked potentials (BAEP), 4 dynamic BAEP patterns could be characterized. These patterns correspond with early and late postoperative hearing outcome. All patients with stable wave V (pattern 1) showed definite hearing preservation, all patients with irreversible abrupt loss of BAEP (pattern 2) lost their hearing, despite early hearing preservation in two cases. All patients with irreversible progressive loss of either wave I or wave V (pattern 3) eventually suffered from definite postoperative hearing loss, despite early hearing preservation in two cases. Those cases with intraoperative reversible loss of BAEP (pattern 4) showed variable short and long term hearing outcome. In 34% hearing was preserved, 44% suffered from postoperative hearing loss, the remaining 22% showed postoperative hearing fluctuation, either as a delayed hearing loss or as reversible hearing loss. Postoperative hearing fluctuation indicates anatomical and functional preservation of the cochlear nerve during surgery and is suggestive of a pathophysiological mechanism initiated during the surgical procedure and continuing thereafter. Patients at risk for delayed hearing loss can be identified during surgery by a characteristic BAEP pattern and may benefit from vasoactive treatment.


Subject(s)
Ear Neoplasms/surgery , Evoked Potentials, Auditory, Brain Stem/physiology , Neuroma, Acoustic/surgery , Audiometry, Pure-Tone , Audiometry, Speech , Cochlear Nerve/physiopathology , Deafness/etiology , Ear Neoplasms/complications , Ear Neoplasms/physiopathology , Humans , Monitoring, Intraoperative , Neuroma, Acoustic/complications , Neuroma, Acoustic/physiopathology , Prognosis , Time Factors
18.
Int J Med Inform ; 55(3): 179-88, 1999 Nov.
Article in English | MEDLINE | ID: mdl-10619288

ABSTRACT

Hospital information systems may contribute in different ways to quality management activities such as monitoring of quality indicators. Most existing quality management activities in hospitals are adjusted to a special medical field or particular disease. These activities often run simultaneously with other procedures and the documentation of patient care. To determine an interdisciplinary integrated quality management procedure, a pilot study was carried out at the Neurosurgery Department and Neonatology Division of the Medical Center of the University of Heidelberg. Predefined generic indicators that may be integrated in an existing information system and used in hospital routine were the basis of this project. The aim of the study was to support the quality management with periodic reports of these indicators. The pilot study showed that there were barriers along the path to an integrated generic quality management. To meet the requirements of routine monitoring, using predefined generic indicators of hospital care, much integration effort, directed at organizational aspects of information processing and information systems architecture, is still needed.


Subject(s)
Hospital Information Systems , Quality Indicators, Health Care , Germany , Hospital Departments/organization & administration , Hospital Information Systems/organization & administration , Humans , Information Storage and Retrieval , Medical Records Systems, Computerized/organization & administration , Neonatology/organization & administration , Neurosurgery/organization & administration , Outcome and Process Assessment, Health Care , Patient Care/standards , Personnel Administration, Hospital , Pilot Projects , Quality Assurance, Health Care/organization & administration , Quality Indicators, Health Care/classification , Quality Indicators, Health Care/organization & administration , Surgery Department, Hospital/organization & administration , Systems Integration
19.
Ophthalmologe ; 94(11): 771-4, 1997 Nov.
Article in German | MEDLINE | ID: mdl-9465707

ABSTRACT

BACKGROUND: Keratoconus is associated with changes in the corneal structure, such as defects of Bowman's layer, a decrease of corneal thickness etc. They result in alterations of some of the biomechanical parameters of the cornea, namely, rigidity and elasticity. The present study was performed to examine how impression tonometry and applanation tonometry for determination of intraocular pressure (IOP) are affected by the changed biomechanical parameters associated with keratoconus. PATIENTS AND METHODS: We examined 20 normal subjects (40 eyes) and 17 keratoconus patients (25 eyes). The corneal thickness was measured by ultrasound pachymetry in the corneal center. In the keratoconus patients, an additional measurement was made at the conus peak. The corneal curvature was determined using the TMS keratoscope. The IOP measurements were made with the Schiötz tonometer (10 g). For comparison, additional IOP measurements in the corneal center and, in the keratoconus group, on the conus peak were made with the applanation tonometer. RESULTS: The normal subjects had a central corneal thickness of 548 +/- 30 microns, compared to 505 +/- 42 microns in the corneal center and 425 +/- 41 microns on the conus peak in keratoconus patients. The average corneal curvature was 43.3 +/- 1.8 D in the normal subjects and 47.8 +/- 4.1 D in keratoconus patients. Applanation tonometry produced results on 11.33 +/- 1.43 mm Hg in the normal group (corneal center) compared to values of 12.00 +/- 2.55 mm Hg (corneal center) and 7.30 +/- 1.95 mm Hg (conus peak) in the keratoconus cohort. The coefficient of rigidity was 0.0236 +/- 0.0026 microliter-1 in the normal subjects, compared to 0.0173 +/- 0.0050 microliter-1 in the keratoconus patients. CONCLUSION: The morphological changes associated with keratoconus may cause tonometry errors.


Subject(s)
Intraocular Pressure/physiology , Keratoconus/physiopathology , Adult , Cohort Studies , Cornea/physiopathology , Elasticity , Female , Humans , Male , Reference Values , Refraction, Ocular , Tonometry, Ocular
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