Journals: redundant publications are bad news.
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Authorship↗
Biomedical subjects
Daniel S Mojon
Publications and source records attributed to Daniel S Mojon.
Detection of nonorganic visual loss with a new optotype chart in simulated malingerers.
BACKGROUND: We tested a new distance and pocket optotype chart for detection of nonorganic symmetrically decreased vision in simulated malingerers. The new optotype used in the charts is based on a subjective contour formed by a misalignment of two line segments. The minimum angle of resolution of this optotype is independent of its size. Subjects claiming to see only the larger optotypes are suspected of malingering. SUBJECTS AND METHODS: 90 normal subjects were asked to simulate symmetrically decreased vision. 60 of these subjects were tested with a distance chart and 30 with a pocket chart. The distance chart was always presented at a fixed distance of 5 m. The pocket chart was moved towards the malingerer until the largest optotype was clearly legible. RESULTS: With the distance chart, 62 % (37/60) of all simulated patients claimed to recognize only the larger optotypes, 33 % (20/60) claimed not to recognize any optotype size, and 5 % (3/60) were able to read all optotype sizes. With the pocket chart, 84 % (25/30) of all simulated patients claimed to recognize only the larger optotypes, 3 % (1/30) claimed not to recognize any optotype size, and 13 % (4/30) were able to read all optotype sizes. The difference between the two distributions of behavior was statistically significant (chi-square statistic, P < 0.005). CONCLUSIONS: Movement of the chart towards the subject (pocket chart) was better at detecting nonorganic visual loss than using a fixed distance (distance chart). Therefore, we suggest to use the pocket chart for the detection of nonorganic disease.
Chi-Square Distribution↗
[A new objective visual acuity test: an automated preferential looking].
BACKGROUND: The Preferential Looking test using Teller acuity cards is widely used for preverbal children but has some weaknesses, in particular because it is examiner dependent and at best half-objective. We tested a new automated method in a pilot study. PATIENTS AND METHODS: In our preferential looking setting we project separate images into the left and right eye. This permits measuring each eye without having to cover the other. An infrared oculography system documents objectively and reproducibly whether or not the stimulus is seen. A square is shown which moves consecutively in a square formation on a background that has the same average brightness. Charting an XY-plot of the eye position results in a square with two diagonals, if the stimulus is seen. By using a specific baby examination unit, this test is already feasible in babies. In this study, the new setting was tested on two children. RESULTS: In two healthy children we found a good correlation between visual acuities determined with the new method and Teller visual acuity charts. Fogging one eye in each of the children resulted in fixation loss of the stimulus when the required visual acuity rose above the fogging value. CONCLUSIONS: This new technique permits one to perform an objective preferential looking test without the need of verbal answers. Larger studies have to validate these preliminary results.
Attention↗
[A new objective test for random-dot stereopsis in preverbal children].
BACKGROUND: The Lang-Stereotest is at best half-objective in testing stereovision in preverbal children. We developed a new method which might objectively measure random-dot stereopsis in preverbal children. PATIENTS AND METHODS: We project two separate random-dot images into the left and right eye using a 3D-monitor. If both eyes are perfectly aligned and random stereopsis is present, the child perceives a stimulus. Four different stimulus positions are shown at random. An infrared oculography system objectively detects whether the stimuli are seen. By using a specific baby examination unit, testing is already feasible in infants. RESULTS: We present the plots of two children with a positive (normal) and two with a negative (pathologic) response to random-dot stimuli. CONCLUSIONS: This new examination technique allows an objective assessment of random-dot stereopsis in non-verbal children. It permits us for the first time to study the development of stereovision under natural conditions. In future, the method may also be used to screen preverbal children for visual abnormalities. Larger studies are required to determine the positive and negative predictive values of this new test.
Child, Preschool↗
[A new method to test vertical ocular deviations using perilimbal light reflexes].
BACKGROUND: To develop a new diagnostic technique to determine vertical ocular deviations when the center of the pupil is covered by swollen eyelids in up- and downgaze. PATIENTS AND METHODS: In upgaze (downgaze) the reflex of a diagnostic lamp held at about 50 cm distance from the patient is observed on the lower (upper) limbus. In the case of an asymmetric reflex, prisms are used to obtain symmetrical reflexes. The amount of prisms indicates the size of the vertical misalignment. In five healthy volunteers, the angles of vertical changes of gaze position were plotted against the prism size needed to recenter the perilimbal reflex. RESULTS: There was a linear correlation between the amount of upgaze changes in degrees and the strength of prisms used for compensation in degrees. This linear correlation was also found in downgaze. For both the correlation coefficient was r = 0.98 +/- 0.01. In upgaze the slope of the average regression line was 0.55 +/- 2.3 degrees, in downgaze - 4.1 +/- 0.8 degrees. A prism of 1 degrees corresponds in upgaze to a vertical deviation of about 1.3 +/- 0.14 degrees, in downgaze to a deviation of about 1.1 +/- 0.07 degrees. CONCLUSIONS: These results demonstrate that the perilimbal light reflex test is suitable for measuring simulated vertical ocular deviations. Therefore, the test may also be used in patients with vertical deviations who cannot be measured with classical methods. The method is more exact for measurements in upgaze.
Adult↗
[Orbital blow-out fractures, a series of 12 operated cases].
BACKGROUND: The management for blow-out fractures is controversial. Some studies suggest early surgical treatment, others a conservative attitude. PATIENTS AND METHODS: We studied retrospectively the data of patients with blow-out fracture, referred to our Neuro-Ophthalmology and Strabismus Clinic from July 1993-May 2000. Out of 48 patients, 22 were operated. We evaluated all 12 patients who underwent pre- and postoperative orthoptic examinations. RESULTS: The patients' age at the time of the accident was 7.8 to 67.8 years (median 25.3). The delay between accident and operation was 2 to 91 days (median 5.5). Eleven patients were operated within 14 days, one after three months. All patients suffered preoperatively from double-vision. Postoperatively the field of fusion augmented, the middle point centralised. The follow-up time was 22 to 915 days (median 251). However, at the last examination, 0.5 to 16 months (median 4.5) after surgery, only seven out of 12 patients were symptom-free. CONCLUSION: Surgical reconstruction within the first week after trauma shows good results concerning ocular motility, sensibility, enophthalme, and field of fusion. An individual evaluation is surely necessary.
Adolescent↗
Association between sleep apnea syndrome and nonarteritic anterior ischemic optic neuropathy.
OBJECTIVE: To determine if patients with nonarteritic ischemic optic neuropathy (NAION) have sleep apnea syndrome (SAS), an entity characterized by repetitive upper airway obstructions during sleep, inducing hypoxia and sleep disruption. METHODS: We recruited 17 patients with NAION and 17 age- and sex-matched controls from patients referred for treatment because of suspected restless legs syndrome. We performed overnight polysomnography and determined the respiratory disturbance index during night sleep, a value used to diagnose and grade SAS. We compared the proportions of patients with SAS among patients with NAION and matched controls using the chi(2) test. Additionally, we compared the proportions of patients with SAS among patients with NAION and a large SAS prevalence study using the binomial test. RESULTS: Twelve (71%) of 17 patients with NAION had SAS. According to the respiratory disturbance index, 4 patients (24%) had mild, 4 patients (24%) had moderate, and 4 patients (24%) had severe SAS. Only 3 (18%) of 17 controls had SAS (P =.005). In the 45- to 64-year age group, 4 (50%) of 8 patients with NAION had SAS; 51 (11.9%) of 430 of the random sample in the prevalence study had SAS (P =.005). In the group older than 64 years, 8 (89%) of 9 patients with NAION had SAS; 18 (24%) of 75 of the random sample in the prevalence study had SAS (P<.001). CONCLUSIONS: We found a high prevalence of SAS in patients with NAION, which supports previous case reports suggesting that such an association exists. This association may explain why approximately 75% of all patients with NAION discover visual loss on first awakening or when they first use vision critically after sleeping. Our findings indicate that SAS may play an important role in the pathogenesis of NAION.
Aged↗
A new optotype chart for detection of nonorganic visual loss.
OBJECTIVE: To develop a new optotype chart for detection of nonorganic decreased vision. DESIGN: Comparative observational case series. PARTICIPANTS: Optotype thresholds determination in three normal subjects and testing on 30 consecutive patients with unclear visual acuity loss. METHODS: A new optotype chart was developed, with an optotype minimum angle of resolution that is independent of size. In three normal subjects rank correlation was calculated between the optotype thresholds and the optotype sizes. A pocket chart was tested in a masked manner on 30 consecutive patients referred because of unclear visual acuity loss. MAIN OUTCOME MEASURES: Optotype thresholds and usefulness in clinical routine (positive and negative predictive values including 95% confidence intervals [CI]). RESULTS: The optotype thresholds did not correlate with the optotype sizes. Ten percent (3 of 30) of the patients referred because of unclear visual acuity loss had to be excluded, because their diagnosis remained unclear. All patients (16 of 16) with organic visual loss saw all optotypes sizes. Eighty-nine percent (10 of 11) of patients with nonorganic visual loss claimed to see only the larger optotypes. The positive predictive value for nonorganic visual loss of the new pocket chart was 100% (CI, 74%-100%); the negative predictive value was 94% (CI, 75%-100%). CONCLUSIONS: The new pocket chart seems to be useful for detection of visual loss caused by nonorganic disease.
Adolescent↗
The Pulfrich phenomenon in a large population of young healthy subjects.
BACKGROUND: To determine whether the Pulfrich phenomenon, an optical illusion occurring in many ophthalmological diseases, is perceived equally in both eyes in a large group of healthy medical students. SUBJECTS AND METHODS: A pendulum bob swinging perpendicular to the direction of observation was observed with either the right or the left eye covered with neutral density filters (50, 80 or 90 % absorption) and the apparent elliptical pendulum movement measured in depth. Interocular time delay was calculated from depth. Data from 65 individuals were included based on having: completed all 7 determinations of depth, a visual acuity of >/= 20/20 on both eyes and an intact stereoscopic perception (Titmus stereotest, acuity of >/= 20/25). RESULTS: All subjects perceived the phenomenon. Depth perception was not significantly different (p > 0.05; MANOVA) between the two eyes (depth in [mm]; mean +/- sem): OD: 8.5 +/- 0.38, 23.7 +/- 0.53, 36.3 +/- 0.81; OS 9.4 +/- 0.50, 24.1 +/- 0.69, 35.6 +/- 0.92; for 50, 80 and 90 % absorption of the filter respectively. At 0 % absorption the pendulum was seen in average at positive values (0.9 +/- 0.23 mm; p > 0.05). Calculated interocular time delay (ms) was: OD: 8.0 +/- 0.18, 5.1 +/- 0.12, 1.8 +/- 0.08; OS: 7.46 +/- 0.15, 5.0 +/- 0.11, 1.9 +/- 0.10. The average depth perceived without filter corresponded to a time delay for the right eye of 0.2 +/- 0.05 ms. Correction for the depth perception perceived without filter did not alter statistical significance. CONCLUSIONS: The Pulfrich phenomenon is perceived equally in both eyes. Depth perception without filters was not significantly different from zero. The illusion has clinical utility, since in normal subjects reliability of measurements is good and size of the illusion (without filters) small.
Adult↗
Exercise-induced vasospastic amaurosis fugax.
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Adult↗
Normal-tension glaucoma is associated with sleep apnea syndrome.
INTRODUCTION: In normal-tension glaucoma, optic nerve damage occurs without elevated intraocular pressures, hence vascular and pathogenic mechanisms other than intraocular pressure effects have been postulated. However, the exact cause(s) remain unknown. We have looked for an association between normal-tension glaucoma and sleep apnea syndrome, a disease characterized by repetitive upper airway obstructions during sleep, inducing hypoxia and sleep disruption with the risk of late cardiovascular and neurological sequelae. METHODS: We performed overnight polysomnography in 16 consecutive Caucasian patients with normal-tension glaucoma. The respiratory disturbance index (RDI) during night sleep was used to diagnose and grade obstructive sleep apnea. Patients with an RDI of 10 or more were diagnosed as having obstructive sleep apnea. RESULTS: We observed the following prevalences of obstructive sleep apnea in normal-tension glaucoma patients: 0% (0 of 2) for the group of patients younger than 45 years, 50% (3 of 6) for the age group 45-64 years, and 63% (5 of 8) for the group older than 64 years. Prevalences in the middle and older age group were significantly higher than in a historic control group (p < 0.025 for both, binomial test). CONCLUSION: Normal-tension glaucoma patients constitute a high-risk population for sleep apnea syndrome. Therefore, they should be screened for sleep apnea syndrome, and, if necessary, be treated to avoid late cardiovascular and neurological sequelae.
Adult↗
Deep sclerectomy with collagen implant: initial experience.
OBJECTIVE: To evaluate complications of deep sclerectomy with collagen implant (DSCI), a recently introduced nonpenetrating glaucoma-filtering surgical technique. PATIENTS AND METHODS: 30 eyes of 23 patients with open-angle glaucoma were included in this prospective, noncomparative, interventional case series. In all eyes, preoperative intraocular pressure (IOP) was lowered inadequately by topical antiglaucomatous medications. After undergoing DSCI, the patients were followed prospectively. If necessary, the procedure was combined with cataract surgery or mitomycin C application. RESULTS: In 27 (90%) of 30 eyes, DSCI could be performed. In 3 (10%) of 30 eyes, DSCI had to be transformed intraoperatively into a trabeculectomy because of a large trabecular penetration. Microperforations without further consequences occurred in 2 (7%) of 30 eyes. The mean follow-up was 6.6 +/- 3.8 months. IOP dropped from 26.0 +/- 6.7 to 13.6 +/- 4.7 mm Hg (p < 0.05). Medical glaucomatous treatment was reduced from 2.3 +/- 3.8 to 0.3 +/- 0.6 (p < 0.05). In cases without cataract, visual acuity decreased from 0.7 +/- 0.3 to 0.66 +/- 0.4 at the last visit (p > 0.1). Postoperative complications included Seidel (1/27, 4%), encapsulated bleb (4/27, 15%), astigmatism (1/27, 4%), iris capture (2/27, 7%), microhyphema (3/27, 11%) and peripheral anterior synechiae (4/27, 15%). Fifteen (56%) of the 27 eyes needed the following postoperative procedures: laser goniopuncture (8/27, 30%), needling of the filtering bleb (4/27, 15%), surgical revision in the operating theater (3/27, 11%). All 3 eyes where trabeculectomy was performed instead of DSCI had a favorable course. CONCLUSIONS: During the evaluation period, complications occurred in about half of the cases. None of the complications was severe or irreversible. Target pressure and a reduction in drug treatment could be achieved in all of the patients.
Aged↗
Normal isopter position in the peripheral visual field in goldmann kinetic perimetry.
PURPOSE: Often in young patients the question arises if a disease state has contracted their peripheral boundary of the visual field. Since the 'hill of vision' is steeper in the periphery, kinetic perimetry is more sensitive in detecting peripheral visual field abnormalities than static perimetry. In order to be able with kinetic perimetry to detect mild peripheral visual field constrictions, we determined the normal position of 4 isopters in the peripheral visual field. SUBJECTS AND METHODS: Intraindividual sensitivity variations of the isopters in the peripheral visual field were determined in 3 normal subjects by one perimetrist. Then, in 22 subjects (19-42 years old) the position of the isopters V4e, III4e, I4e and I3e has been determined by one perimetrist. Visual fields were registered using a Goldmann kinetic perimeter. RESULTS: The intraindividual sensitivity variations (measured as 1 standard deviation) for the isopter V4e was 0.98 degrees and for the isopter I4e 1.13 degrees. To visualize the normal isopter positions in the peripheral visual field, the average positions +/- 2 standard deviations were plotted for the isopters V4e, III4e, I4e and I3e. CONCLUSION: In this study, we determined the normal position of 4 isopters frequently used to plot the peripheral visual field. The plots have been printed in a scale of 1:4 in order to facilitate its use. Photocopying the figures on transparencies by scaling them with a factor 4 will allow to superpose the transparencies on individual Goldmann kinetic visual fields in order to easily determine whether the individual isopters are inside or outside the normal range.
Adult↗
Low specificity of scanning laser polarimetry.
PURPOSE: Scanning laser polarimetry is used to assess the peripapillary retinal nerve fiber layer. This study evaluates scanning laser polarimetry in normal subjects. SUBJECTS AND METHODS: 28 eyes of 28 normal subjects (age range 21-48 years, mean age 36.5 years) had scanning laser polarimetry (NFA-GDx, Laser Diagnostic Technologies, San Diego, Calif., USA). All subjects had normal eye examinations, refractive errors with spherical equivalents <5 D and astigmatism <2 D, normal intraocular pressures, no history of diseases affecting the visual field or nerve fiber layer, and normal white-on-white automated perimetry (Octopus 101, program G2). The mean image of three good-quality measurements with the scanning laser polarimeter was included. RESULTS: 36% of the normal subjects (10/28) had at least one NFA parameter outside normal (p < 0.05). The parameters most frequently found to be outside normal were symmetry (21%, 6/28) and superior ratio (17%, 5/28). CONCLUSIONS: Scanning laser polarimetry is often used for early detection of glaucomatous damage in glaucoma suspects. This study found a specificity of only 64% and indicates that the actual selection of parameters is not adequate. Especially the parameters symmetry and superior ratio should be reevaluated in order to achieve a higher specificity.
Adult↗
Normal values of short-wavelength automated perimetry.
BACKGROUND: The purpose of this study was to evaluate short-wavelength automated perimetry (SWAP, i.e., blue-yellow) in normal volunteers and to review the current normal values provided by the manufacturer. METHODS: 28 eyes of 28 normal subjects (age range 21-48 years, mean age 36.5 years) had SWAP (Octopus 101, two phases of program G2, Interzeag AG, Schlieren, Switzerland). All subjects had normal eye examinations, refractive errors with spherical equivalents <5 diopters and astigmatism <2 diopters, normal intraocular pressures, no history of diseases affecting the visual field or nerve fiber layer, and normal white-white automated perimetry (Octopus 101, program G2). RESULTS: 21% of the subjects (6/28) had to be excluded since visual field testing was not reliable (reliability factor >5%). With the normal values provided by the manufacturer, only 45% of the remaining subjects (10/22) had all other indices within normal limits. With the appropriate normal values based on the multicenter SWAP Octopus 101 study, 11% (3/28) were beyond the normal range: all had abnormal high sensitivities - 2 due to false-positive response. The normal value range for the index Mean Defect is remarkably wide (5.-, median, 95.- percentile: -4.4, -0.5, +5.3 dB, respectively). The normal value range for the index Loss Variance is surprisingly low and similar to standard perimetry (5.-, median, 95.- percentile: -1.7, 6.8, +21.2 dB(2), respectively). CONCLUSION: SWAP with the Octopus G2 program reaches appropriate specificity but only if the correct normal values of the multicenter SWAP Octopus 101 study are used. The variability between subjects is remarkably large. The variability within a visual field is similar for SWAP and standard perimetry as reflected by similar values for the visual field index Loss Variance. Further studies have to establish the sensitivity to detect a disease for SWAP on the Octopus 101.
Adult↗
Conservative treatment of vertical diplopia in a patient with silent sinus syndrome.
Silent sinus syndrome is a rare disease of the maxillary sinus characterized by bony absorption processes leading to progressive sinus wall thinning with consecutive enophthalmos and hypoglobus. It represents a benign cause of acquired enophthalmos and is often accompanied by painless vertical diplopia, the latter treated surgically in all cases published to date. We report a 56-year-old patient with silent sinus syndrome in whom vertical diplopia was treated with prisms showing that conservative treatment alone may, in mild cases, be an effective alternative to reconstructive surgery.
Diplopia↗
Influence of cycloversions induced by head tilt on scanning laser polarimetry parameters.
OBJECTIVE: To study the influence of cycloversions induced by head tilt on parameters of scanning laser polarimetry. METHODS: Five left and five right eyes of 9 normal subjects were measured in seven different head tilt positions by one examiner using a scanning laser polarimeter (Nerve Fiber Analyzer, NFA II, LDT Inc., San Diego, Calif., USA). Images were acquired for the following head tilt positions: upright, 10, 20, 30 degrees to the right, and 10, 20, 30 degrees to the left. For each position five to eight images of the peripapillary area were recorded. Objective cycloversions were determined trigonometrically on the fundus pictures provided by the scanning laser ophthalmoscope. Parameters acquired for different head positions were compared using a Friedmann's two-way analysis of variance. RESULTS: Average objective cyclodeviations were 5.9 degrees for the 10 degrees head tilts, 11.2 degrees for the 20 degrees head tilts, and 18.9 degrees for the 30 degrees head tilts. Head tilts to the right in left eyes and to the left in right eyes (both of them corresponding to an incycloposition) induced a significant increase in several parameters (p < 0.05). Head tilts to the left in left eyes and to the right in right eyes (both corresponding to an excycloposition) showed no influence on parameters (p > 0.05). CONCLUSIONS: Ocular incycloposition has a significant influence on several scanning laser polarimetry parameters. Therefore, evaluation is limited in patients having an incyclorotation of the nonfixating eye with the head in an upright position or in patients having a head tilt inducing an incyclorotation.
Adult↗
Automated analysis of eye tracking movements.
OBJECTIVE: To present a quick algorithm to automatically analyze the raw data acquired by a photo-oculography (POG) system. METHODS: We developed a simple algorithm for POG data analysis based on an extrapolation of missing values due to blinking and on exclusion of outliers using the robust mean and standard deviation. RESULTS: POG curves of 4 children aged between 1.5 and 7 years are shown before and after automatic analysis. After applying our algorithm, the curves are much smoother. CONCLUSION: Our algorithm allows a quick data analysis and will help to better interpret and analyze POG data.
Algorithms↗