Comparison of psychophysical and electrophysiological testing in early glaucoma

PURPOSE: To compare the sensitivity and specificity of a wide range of psychophysical and electrophysiological tests in the detection of early glaucomatous damage. METHODS: Forty-three normals and 43 patients with early glaucoma, some still without field defects, were tested with differential light threshold perimetry, short-wavelength automated perimetry, high-pass resolution perimetry, motion detection, flicker contrast sensitivity, flickering and isoluminantly matched letter tests, and pattern and flash electroretinography, including photopic, scotopic, oscillatory potentials, and 30 Hz flicker. Receiver operating characteristic analysis was applied to continuous variables derived from each of the tests. RESULTS: Most parameters reflected glaucomatous loss to some degree, even though only single variables were analyzed separately in the receiver operating characteristic analysis. The pattern electroretinogram and some of the letter acuity tests had the best sensitivity and specificity, followed by short-wavelength automated perimetry and high-pass resolution-perimetry. Motion detection, flicker contrast, and flash electroretinogram parameters scored poorly. Six patients with normal results on the Humphrey field test had abnormal results on many of the other tests. CONCLUSIONS: Applying different psychophysical and electrophysiological tests may add to our ability to detect early glaucomatous damage.     

Beyond insecurity: a reconceptualization of attachment disorders of infancy

Since the appearance of Campbell and Maffei's and Harter and White's reports it has been well established that the visual evoked potential (VEP) can be used to predict psychophysical contrast sensitivity and visual acuity and is thus suited as an objective technique to assess these fundamental aspects of vision. Nevertheless, the technique has not become a standard diagnostic tool, being too time-consuming to apply and suffering from variable reliability under pathological visual conditions. In addition, there are problems of reliability in normal subjects. By using an unconventional stimulus--temporally sinusoidal 16-Hz on-off modulation of sinewave gratings--we demonstrated that these problems can be alleviated in normal subjects. This stimulus avoids the low signals in the visible range that frequently occur with conventional pattern-reversal stimuli, it leads to high correspondence between normal observers, and it is much faster to apply than are transient VEPs. Initial applications of this stimulus to amblyopes yielded promising results. The steady-state VEP could consequently turn into a viable diagnostic procedure in disturbances of visual contrast perception.     

Determination of long-life radiocesiums Cs-134 and Cs-137 in food by gamma-ray spectrometry: summary of collaborative study

PURPOSE: The authors evaluated the ability of a confocal scanning laser ophthalmoscope to detect glaucomatous visual field loss by using their previously described discriminant formula on a prospectively obtained cohort. The relationship of optic disc size to diagnostic classification was also evaluated. METHODS: One eye was chosen randomly from each of 153 subjects. Sixty control eyes had intraocular pressure less than 21 mmHg and normal visual fields; 93 glaucomatous eyes had intraocular pressure greater than 21 mmHg and abnormal visual fields. The optic disc status purposely was not used for classification purposes. All subjects were examined with the Heidelberg Retina Tomograph (HRT; Heidelberg Engineering GMBH, Heidelberg, Germany) and Humphrey Perimeter, program 30-2 (Humphrey Instruments, Inc., San Leandro, CA). Visual fields were considered abnormal by the authors' previously published criteria. The HRT classification used age, adjusted cup shape measure, rim volume, and height variation contour to classify the optic disc as normal or glaucomatous. Then the authors assessed the sensitivity, specificity, and diagnostic precision for the entire group, and for three subsets classified by disc area: disc area less than 2 mm2, between 2 and 3 mm2, and more than 3 mm2. RESULTS: The entire group had a sensitivity, specificity, and diagnostic precision of 74%, 88%, and 80%, respectively. The specificity was 83% when disc area was less than 2 mm2 and improved to 89% when disc area was more than 2 mm2. The sensitivity tended to improve from 65% to 79%, and to 83% if the disc area increased, but the difference was not statistically significant. CONCLUSIONS: In a prospective cohort of patients, the HRT discriminant analysis formula was capable of detecting glaucomatous visual field loss with good precision. Unusually small optic discs continue to present diagnostic difficulties.     

The cupped disc. Who needs neuroimaging?

OBJECTIVE: To determine the incidence of positive neuroradiologic studies in consecutive patients with glaucoma associated with normal intraocular pressure and to compare the psychophysical and clinical characteristics of these eyes with eyes with disc cupping associated with intracranial masses. DESIGN: Retrospective case-controlled study. PARTICIPANTS: Fifty-two eyes of 29 patients with glaucoma associated with normal intraocular pressure and 44 eyes of 28 control patients with compressive lesions were reviewed. INTERVENTION: The medical records of consecutive glaucoma patients with normal intraocular pressure who underwent brain magnetic resonance imaging or computed tomography scanning as part of a diagnostic evaluation between January 1, 1985, and July 1, 1995, were reviewed. A masked reading of optic nerve photographs and visual fields was performed by one observer. A similar analysis was performed on a control group of consecutive patients with nonglaucomatous optic nerve cupping with known intracranial mass lesions. MAIN OUTCOME MEASURES: The neuroradiologic findings, clinical characteristics, optic nerve head appearance, and patterns of visual field loss were compared between groups. RESULTS: None of the patients diagnosed with glaucoma had neuroradiologic evidence of a mass lesion involving the anterior visual pathway. Compared to control subjects, patients with glaucoma were older (P = 0.0001), had better visual acuity (P = 0.002), greater vertical loss of neuroretinal rim tissue (P = 0.0001), more frequent optic disc hemorrhages (P = 0.01), less neuroretinal rim pallor (P = 0.0001), and more nerve fiber bundle visual field defects aligned at the horizontal midline (P = 0.0001). Visual acuity less than 20/40, vertically aligned visual field defects, optic nerve pallor in excess of cupping, and age younger than 50 years were 77%, 81%, 90%, and 93% specific for nonglaucomatous cupping associated with compressive lesions, respectively. CONCLUSIONS: Anterior visual pathway compression is an uncommon finding in the neuroradiologic evaluation of patients with a presumptive diagnosis of normal-tension glaucoma. Younger age, lower levels of visual acuity, vertically aligned visual field defects, and neuroretinal rim pallor may increase the likelihood of identifying an intracranial mass lesion.     

Identification of early glaucoma cases with the scanning laser ophthalmoscope

PURPOSE: This study aimed to define the confocal laser scanning ophthalmoscope (Heidelberg Retina Tomograph [HRT]) parameters that best separate patients with early glaucoma from normal subjects. STUDY DESIGN: A cross-sectional study. PARTICIPANTS: A total of 80 normal subjects and 51 patients with early glaucoma participated (average visual field mean deviation = -3.6 dB). INTERVENTION: Imaging of the optic nerve head with the HRT and analysis using software version 1.11 were performed. MAIN OUTCOME MEASURES: The relation between neuroretinal rim area and optic disc area, and cup-disc area ratio and optic disc area, was defined by linear regression of data derived from the normal subjects. The normal ranges for these two parameters were defined by the 99% prediction intervals of the linear regression between the parameter and optic disc area, for the whole disc, and for each of the predefined segments. Normal subjects and patients were labeled as abnormal if the parameter for either the whole disc or any of the predefined segments was outside the normal range. The sensitivity and specificity values of the method were calculated. RESULTS: The highest specificity (96.3%) and sensitivity (84.3%) values to separate normal subjects and those patients with early glaucoma were obtained using the 99% prediction interval from the linear regression between the optic disc area and the log of the neuroretinal rim area. Similar specificity (97.5%) and lower sensitivity (74.5%) values were obtained with the 99% prediction interval derived from regression between the disc area and cup-disc area ratios. Poor separation between groups was obtained with the other parameters. CONCLUSIONS: The HRT, using the technique of linear regression to account for the relationship between optic disc size and rim area or cup-disc area ratio, provides good separation between control subjects and patients with early glaucoma in this population.     

zALK-8, a novel type I serine/threonine kinase receptor, is expressed throughout early zebrafish development

AIMS: Progressive loss of neuroretinal rim tissue is known to occur early in glaucoma and measurement of the neuroretinal rim area is possible by magnification corrected analysis of optic disc photographs (planimetry). This study was performed to determine whether the facility to distinguish between glaucomatous and normal optic discs could be improved upon by: (a) taking into account the known relation between optic disc size and neuroretinal rim area, and (b) measuring rim area in a number of segments, in order to detect focal changes. METHODS: Planimetric examination of the optic disc photographs of 88 control subjects and 51 patients with early visual field defects was performed. In the control group, multiple linear regression analysis was performed between neuroretinal rim area and optic disc area, age, sex, eye side, refraction, and keratometry. This was repeated for the whole disc and for each of twelve 30 degree segments. Normal ranges were defined by the 98% prediction intervals of the regression analysis and the sensitivity and specificity for correct identification of optic discs in the two groups determined. RESULTS: Multiple linear regression demonstrated significant associations between the neuroretinal rim area and optic disc area and age in normal subjects. Sensitivity and specificity for glaucoma diagnosis, using the cut off derived from the 98% prediction intervals, was 37.7% and 98.9% respectively when total neuroretinal rim area alone was considered, and 88.7% and 94.3% respectively when the 30 degree segments were included. The most frequent pattern of neuroretinal rim loss was diffuse, followed by thinning in more than one sector and then by thinning in the inferotemporal sector alone. CONCLUSIONS: This method of optic disc analysis enables the examiner to identify glaucomatous optic discs at the stage of early perimetric loss with a high degree of precision. Optic disc photography is simple, and fundus cameras are widely available. This method for glaucoma case identification may therefore be suitable for the primary care setting as well as hospital practice.     

Nerve growth factor effects on the song control system of zebra finches

PURPOSE: The authors present the "pattern" visual evoked potentials (VEP) analysis with use of the artificial neural networks (ANN). MATERIALS AND METHODS: The study involved 11 patients with compressive chiasmal optic neuropathy, 20 patients with optic neuritis, 12 patients with anterior ischaemic optic neuropathy, 20 patients with optic nerve atrophy from neuritis, 8 patients with demyelinative neuropathy, 5 patients with oedema optic nerve, 20 healthy persons. The tests of visual evoked potentials were performed with the use of computer system UTAS-E1000. Classification of potentials was made by correlation of outputs of ANN with results of confirmed neuro-ophthalmology conditions. RESULTS: ANN of different architecture were classified correctly in 80-100% of VEP record samples. CONCLUSIONS: The obtained correctness of classification confirms usefulness of VEP analysis as the objective diagnostic method in some neuro-ophthalmological diseases and indicates application of ANN in multifactor analysis.     

Residual symptoms and signs after untreated acute optic neuritis. A one-year follow-up

PURPOSE: To study the symptoms and signs one year after optic neuritis. METHODS: Seventy population-based untreated patients, (44F, 26M; median age 35 years, range 14-48 years) were eligible for study, but the 11 bilateral cases were excluded. Among 59 patients participating in a one-year follow-up of the visual function, 58 answered a questionnaire. RESULTS: At follow-up 59% of the patients complained of visual impairment, though 49% of these patients had a Snellen visual acuity of 6/9 or better. The affected eyes showed decreased visual acuity in 34%, decreased contrast sensitivity in 63%, an abnormal score in 40% with the Lanthony D-15 desaturated panel, and in 13% with the Ishihara test, prolonged latencies of VEP in 58%, and decreased amplitudes of VEP in 41%. CONCLUSIONS: All tests except for VEP correlated significantly to the degree of perceived visual impairment. Subjective visual complaints and more sensitive tests than visual acuity should be used to evaluate the visual function following optic neuritis.     

Morphometric analysis of the optic disc surface. The level of smoothness as a diagnostic parameter for glaucoma

PURPOSE: Since the glaucomatous loss of nerve fibers changes the appearance of the optic disc, we evaluated the morphology of the surface of the optic disc in normal and glaucomatous eyes by using a computerized system to provide the reciprocal position of a large number of points placed on its surface in order to study the clinical significance of differences in the 'smoothness' of optic disc surface. METHODS: The morphology of the optic disc surface was evaluated by means of simultaneous stereoscopic videographic pictures (IMAGEnet X Rev-3.51b-Topcon Europe, The Netherlands): the reciprocal distribution of a large number of points located on the surface of one eye of 100 subjects randomly chosen (45 normal and 55 glaucoma patients) was studied. In order to define the level of 'smoothness' of the optic disc surface, the differences of the relative position of each surface point were studied by measuring the standard deviation (SD) from the average heights of the points (n. ranging from 623 to 1916 depending on the size of the disc area) that identify the optic disc surface. RESULTS: The coefficient of variation of the reciprocal location of the points, placed on the optic disc surface at the different measurements performed by a single operator was 10.4%. The differences in Optic Disc Surface Smoothness (ODSS) between glaucoma and normal group were statistically significant (p < 0.0001 using Mann-Whitney U test). No correlation was detectable between age and standard deviation. The best threshold value, calculated using ROC methodology, able to separate the two groups was: normal group: SD < or = 17.79 (-1 x 10(-2) mm); glaucoma group: SD > -17.79 (-1 x 10(-2) mm). Such threshold value had a sensitivity of 82.1%, a specificity of 92.2% and a diagnostic precision (DP) of 86.5% in dividing the glaucoma group from the normal group. CONCLUSION: ODSS is a global index of optic disc conditions based on quantitative measurements of the morphology of the optic disc surface. As such it does not provide information about the location and the characteristics of optic disc damage. Nevertheless, ODSS measurement is able to separate normal from glaucomatous optic disc with a rather interesting sensitivity, specificity and diagnostic precision (DP). As such it could be useful both for research and clinical applications.     

Stability of rifampin in plasma: consequences for therapeutic monitoring and pharmacokinetic studies

Several animal studies have shown an anatomical and functional separation between the ON- and OFF-pathways in the retina and in the lateral geniculate nucleus. Psychophysical studies in humans have also documented separate pathways that process increments and decrements of light. However, at the level of the visual cortex, there is electrophysiological evidence of interactions between the ON- and OFF-pathways. In addition, psychophysical studies have shown that these pathways can exhibit differential sensitivity and be differentially adapted. These findings motivated an electrophysiological study to gather further evidence of processing within the ON- and OFF-pathways in the human visual system. Using sawtooth stimulus modulation, we measured the visual evoked potential (VEP) before and after adaptation to both rapid-on and rapid-off sawtooth stimuli. The effect of adaptation was determined by comparing the VEP response in three test conditions: without adaptation, after adaptation to the same sawtooth polarity, and after adaptation to the opposite sawtooth polarity. The results reveal a selective adaptation effect, which provides physiological evidence for separate processing of increments and decrements in the human visual system. We conclude that with appropriate stimulus parameters, the VEP can serve as an objective measure of processing within the ON- and OFF-pathways in humans.     

Use of scanning laser ophthalmoscopy to monitor papilloedema in idiopathic intracranial hypertension

AIMS: To determine the sensitivity of confocal scanning laser ophthalmoscopy (SLO) in detecting clinically significant changes in papilloedema secondary to idiopathic intracranial hypertension (IIH) and the correlation with visual field loss. METHODS: Eight patients--three new, two recurrent, and three chronic cases of IIH--were examined over a 9 month period with SLO (Heidelberg retina tomograph) of optic nerve head and 30-2 Humphrey visual fields (six cases). Optic disc swelling (volume) was assessed in each eye using a circular contour line placed around the swollen optic nerve head on the mean image of three topographic images. Nine volume measurements from single images in each eye of every patient were performed on one occasion to assess repeatability. RESULTS: In the five acute cases optic disc volumes (range 1-16 mm3) decreased with treatment to stable, normal levels. Three of these had mild, reproducible, field defects which resolved. Two chronic cases had stable or fluctuating disc volume with no detectable change in grade of papilloedema and mild field loss. In one case which underwent theco-peritoneal shunting both disc volume and field worsened, indicating therapeutic failure. Both improved postoperatively. CONCLUSIONS: SLO has a high sensitivity for detecting small changes in disc volumes and correlates closely with visual field change in the short term. It can confirm therapeutic failure by detecting stable or increasing disc volume. Decreasing volume may indicate resolution of papilloedema or secondary optic atrophy, so accompanying funduscopy and visual fields remain essential.     

Topographic distribution of visual evoked potentials in optic neuropathy

INTRODUCTION: Digital treatment of electrical signals coming from the central nervous system on stimulation of the optic nerve path offers an objective method for evaluation of visual evoked potentials (VEP) shown graphically on a cerebral map. OBJECTIVE: To evaluate the topographical distribution of VEP in cases of optic neuropathy adding this parameter to the usual parameters of latency and amplitude. MATERIAL AND METHODS: We studied 35 patients with suspected optic neuropathy and normal findings on basic ophthalmological examination, in whom VEP and VEP mapping (VEPM) was done. RESULTS: In 26% of the cases there was no response for evaluation with the usual VEP recording techniques, whilst in those with VEPM this percentage was reduced to 11.5%. In the other cases there was a potential with characteristic distribution in the occipital areas and a maximally positive dipole posteriorly. CONCLUSION: VEPM is an objective method for evaluation of the visual pathway offering better discrimination than the usual VEP in more severe cases of neuropathy.     

Blue-on-yellow and achromatic perimetry in diabetic children without retinopathy

OBJECTIVE: We compared blue-on-yellow perimetry with achromatic perimetry to determine whether the first was more sensitive in detecting visual field defects. RESEARCH DESIGN AND METHODS: We studied 50 children and adolescents (22 male, 28 female) with IDDM, ranging in age from 10.1 to 16.3 years (mean 13.3+/-2.1 years), with a disease duration of 5.2-10.0 years (mean 7.1+/-1.9 years). Patients were divided into subgroups according to the presence of persistent microalbuminuria. No one had signs of diabetic retinopathy when studied with fluorescein angiography. RESULTS: By achromatic perimetry, the analysis of subareas of the central 30 degrees of the visual field (0-9 degrees; 10-18 degrees; out of 18 degrees) showed no differences between diabetic subgroups in the central 18 degrees of the visual field, while a significant difference between the same subgroups was found outside the 18 degrees of the 24-2 program of the Humphrey perimeter (P = 0.027). By blue-on-yellow perimetry, in all three of the perimetric subareas evaluated, the sensitivity was lower in microalbuminuric patients than in normoalbuminuric ones. The differential sensitivity between the perimetric tests performed with blue-on-yellow and with achromatic stimuli showed statistically significant data, with a higher level of significance in the central 18 degrees (P < 0.0001) than outside the 18 degrees (P = 0.033). CONCLUSIONS: Our study suggests that blue-on-yellow perimetry is more useful and more sensitive than achromatic perimetry in the detection of preclinical visual field defects in diabetic children with microalbuminuria but without clinically detectable retinopathy.     

Foveal dysfunction and central visual field loss in glaucoma

OBJECTIVE: To determine whether foveal function distal to the ganglion cell layer is an independent predictor of central visual field function in glaucoma. SETTING: University affiliated hospital and private practice. PARTICIPANTS: Twenty-seven eyes (27 patients) with normal-pressure glaucoma, 10 eyes (10 patients) with primary open-angle glaucoma, and 47 eyes of 47 matched normal volunteers. INTERVENTION AND MAIN OUTCOME MEASURES: Foveal cone electroretinogram (ERG) amplitude, relative optic cup to disc area and their relations to Humphrey full-threshold 30-2 visual field central 4-point mean total deviation (C4MTD) and pattern deviation (C4MPD). RESULTS: Foveal cone ERG amplitude was subnormal in 14 (37.8%) of the 37 glaucomatous eyes and lower in the glaucoma group compared with normal eyes (P<.01). The C4MTD and C4MPD were lower in glaucomatous eyes with subnormal amplitudes compared with those with normal amplitudes (P<.01 and P<.05, respectively). Amplitude was directly correlated with C4MTD (P<.01) and C4MPD (P<.01). Relative optic cup to disc area was inversely correlated with C4MTD (P<.001) and C4MPD (P<.001). Partial correlation analysis revealed that amplitude and relative optic cup to disc area were independent predictors of C4MTD and C4MPD. CONCLUSION: Foveal function distal to the ganglion cell layer and optic disc cupping independently predict central visual field function in glaucoma.     

Visual evoked potentials in patients with refraction amblyopia in the presence of high myopia

The informative value of a method for assessing the degree of amblyopia, developed by the author, was assessed in examinations of 16 children (29 eyes) with ametropic amblyopia caused by high myopia and 41 healthy controls. The method consists in recording the pattern-reversal visual evoked potentials (VEP) evoked by 4 patterns of different checksize and contrast. A relationship has been revealed between the VEP types detected by the proposed method and the degree of amblyopia (degree of vision acuity loss). The author came to a conclusion that in ametropic amblyopia, similarly as in stimulus deprivation amblyopia, changes of VEP develop that reflect the deterioration of contrast sensitivity function in low spatial frequencies. The developed VEP method with the modifications described in this paper may be useful in the diagnosis and objective evaluation of the degree of amblyopia.     

Influence of optic disc size on the sensitivity of the Heidelberg Retina Tomograph

PURPOSE: The aim of this study was to evaluate the influence of optic disc size on the ability of variables generated by the Heidelberg Retina Tomograph, software version 1.11, to distinguish glaucoma patients from normals in a cross-sectional study. PATIENTS AND METHODS: For evaluation of the optic disc with the Heidelberg Retina Tomograph, eyes of 87 normals and 61 glaucoma patients were selected. Disc area, volume above reference, rim area, cup area, cup volume, third moment in contour and the mean retinal nerve fibre layer thickness at the border of the optic disc were selected for evaluation. The sensitivity at 80% specificity of these variables was calculated under three conditions: (1) no correction for disc size; (2) calculation in the following disc size ranges: class I (1.0-2.0 mm2), class II (2.0-2.5 mm2), class III (2.5-3.15 mm2) and class IV (3.15-5.0 mm2); (3) calculation globally, taking into account the different disc sizes of the four classes. RESULTS: Neuroretinal rim area, cup area and volume, third moment and nerve fibre layer thickness were significantly and positively correlated with optic disc size in normals. Neuroretinal rim volume measurements were statistically independent of optic disc size. Sensitivity was lowest when the size of the optic disc was not considered. Sensitivity increased when evaluated in four optic disc size classes. With growing optic disc size sensitivity of the retinal nerve fibre layer increased and third moment value decreased. Cup volume and area had their lowest sensitivity for large optic discs. The area of the neuroretinal rim was the only variable which showed similar sensitivity values under all three conditions. CONCLUSIONS: The sensitivities of HRT variables varied with optic disc size. Evaluation of their sensitivity requires the definition of optic disc classes or statistical correction for the size of the optic disc.     

Retinal ganglion cell layer and visual function in a patient with optic disc drusen

BACKGROUND: To correlate the retinal ganglion cell pattern to visual acuity and visual field data in a patient with bilateral optic disc drusen, a quantitative clinicopathological study was carried out. METHODS: Both retinae of a patient with optic drusen were whole-mounted. Retinal ganglion cell counts were made using a sampling scheme covering the whole retina and compared to the findings in 10 normal retinae. Relative ganglion cell reduction in the drusen retinae was correlated to clinical data. RESULTS: The total retinal ganglion cell count was reduced from 1244858+/-98736 in normal retinae to 305319 on the right and 527571 on the left eye with optic disc drusen. Large ganglion cells had a better chance of survival. Parafoveal ganglion cell loss was 57% for the right and 36% for the left eye, while visual acuity was 0.8 and 1.0 respectively. The mean light sensitivity loss increased from the centre (6.2 dB) to paracentral (9.9 dB), mid-peripheral (13.7 dB) and outer peripheral (15.0 dB) retina, while ganglion cell losses were smallest in outer peripheral retina (21.9%), followed by central (53.0%), mid-peripheral (70.9%) and paracentral retina (87.7%). CONCLUSION: These data validate Frisén's theory on central retinal resolution and provide the structural basis for the clinical rule that low visual acuity should not be attributed to disc drusen. Automated light sense perimetry gives an inadequate picture of retinal damage caused by optic disc drusen.     

Visual disturbance: where do I look?

Visual disturbances often signal serious ophthalmic disease. Comprehensive general medical and ophthalmic histories are most helpful. Information about the animal's vision, based on its performance in familiar and unfamiliar environments, should be obtained from the owner. As bilateral involvement and visual disturbances are often associated with systemic diseases, a complete physical examination is indicated. The ophthalmic examination consists of a series of diagnostic procedures to isolate and define the ophthalmic disorder. Several clinical tests can be performed easily in the examination room, including the light-induced pupillary reflex, the dazzle or photic reflex, the menace reflex, the obstacle course test and, if indicated, the flash electroretinogram, the visual evoked response and, recently, the pattern electroretinogram. Ophthalmic diseases that produce visual disturbances in dogs often affect the cornea, aqueous pathways, lens and ocular fundus; in cats, they usually affect the uveal tract and are associated with serious systemic diseases. Orbital diseases are not usually associated with visual disturbance unless the optic nerve is involved. Corneal diseases and cataract formation that involve the visual axis and pupillary aperture often cause visual disturbance. Inflammations of the Iris and ciliary body can produce both acute and long-term visual disturbance and even blindness. Diseases of the retina and optic nerve usually present as visual disturbances in the absence of pain.     

The kinin system in rhinitis and asthma

During detailed visual function testing, pattern-reversal visual evoked potentials (VEP), generated by different spatial frequencies (3 c/d, 1 c/d and 0.6 c/d) and visual contrasts (100% and 10%) were recorded in 21 adolescent and young adult phenylketonuric (PKU) patients (11 females and 10 males; mean age 14.8 years, range 9-22.8) on and off diet. In 14 of the 21 patients, disease had been detected at neonatal screening and in 7 later. Ten age-matched healthy subjects acted as controls. Recordings in more than 40% of eyes in the whole group and 30% of eyes in the screening subgroup showed a prolonged P100 latency. All visual pattern stimuli elicited a significantly longer P100 latency in PKU patients than in controls. VEP latencies to 3 c/d, 1 c/d and 1 c/d with 10% contrast--but not to 0.6 c/d--were longer in patients off diet than in patients on diet. No differences were found between VEP latencies in early- and later-detected subjects. To study the link between biochemical variables and VEP latencies, we envisaged either a linear relationship between recent exposure to phenylalanine (Phe) and VEP abnormalities or a threshold model considering phenylalanine (Phe) concentrations among the factors influencing VEP latencies. The correlation analysis detected an association between plasma Phe concentrations and abnormal VEP latencies, predicting that plasma Phe concentrations > 901 mumol/L would prolong VEP latencies to 1 c/d; concentrations > 879 mumol/L would prolong latencies to 3 c/d; and concentrations > 898 mumol/L would prolong latencies to 1 c/d with 10% contrast.     

Neuroretinal rim width ratios in morphological glaucoma diagnosis

AIMS: To evaluate the inferior to temporal neuroretinal rim width ratio and superior to temporal rim width ratio as measures of rim shape for diagnosis of glaucoma. METHODS: Colour stereo optic disc photographs of 527 normal subjects, 100 ocular hypertensive individuals with normal visual fields, and 202 open angle glaucoma patients with a mean perimetric defect of less than 10 dB were morphometrically evaluated. Eyes with an optic cup area of < 0.2 mm2 were excluded. RESULTS: In the normal subjects, inferior to temporal rim width ratio (1.67 (SD 0.53)) was significantly (p < 0.0001) higher than superior to temporal rim width ratio (1.56 (0.49)). Both ratios were significantly (p < 0.0001) higher the more vertically the optic disc was configured. In the normal eyes, both ratios were statistically independent of disc size, rim area, refractive error, age, and sex. With the differences being more marked for the inferior to temporal ratio than for the superior to temporal ratio, both rim width ratios were significantly (p < 0.005) lower in the ocular hypertensive group than in the normal group. Despite the high significance of the differences, diagnostic power of the inferior ratio and the superior ratio was 59% and 58%, respectively, indicating a marked overlap between the groups. CONCLUSIONS: Abnormally low inferior to temporal and superior to temporal rim width ratios can indicate glaucomatous optic nerve damage in some ocular hypertensive eyes. Being independent of optic disc size and ocular magnification, the rim width ratios may be taken as one among other variables for the ophthalmoscopic optic disc evaluation, taking into account, however, a pronounced overlap between normal eyes and ocular hypertensive eyes.