Lens-corrected visual field sensitivity and diabetes.

PURPOSE: To examine whether peripheral S-cone system and achromatic sensitivity was reduced in patients with diabetes compared to normal controls. METHODS: Perimetric measurements were obtained to study peripheral S-cone system and achromatic sensitivity in patients with diabetes and normal controls. Measures of individual lens absorption of short-wavelength light were used to correct visual field sensitivity values for attenuation of test light due to lens absorption. RESULTS: Both before and after correction for lens absorption of test spot light, peripheral field-averaged S-cone system and achromatic sensitivities were not significantly reduced among patients with diabetes compared to normals of the same age. However, localized sensitivity losses in the visual field were found in most patients with diabetes both before and after lens absorption correction, compared to age norms. The amount of localized loss (number of field locations with reduced sensitivity) was significantly correlated with the level of retinopathy. Statistical analysis showed that after the effects of age and duration were removed, field-averaged S-cone system sensitivity in patients with diabetes was also significantly reduced as a function of increasing severity of retinopathy. CONCLUSIONS: Patients with diabetes may have areas of reduced S-cone system sensitivity with development of diabetic retinopathy.

Lenses of diabetic patients "yellow" at an accelerated rate similar to older normals.

The authors used a psychophysical method to measure lens transmission of young, type I diabetic patients and normal controls. The results from normal controls agreed with previously published reports of decreasing lens transmission with age, and those from diabetic subjects suggested that lenses of young, type I diabetic patients age or "yellow" at an accelerated rate that was similar to that of normal controls over the age of 60 yr. The rate of accelerated lens density that occurs per year with the duration of diabetes is similar to the rate of accelerated lens density that occurs per year with patient age over 60 yr. A possible molecular explanation for the accelerated lens yellowing in both populations is discussed. Both diabetic individuals and the older normal populations have elevated plasma glucose levels and therefore may have accelerated glycosylation of lens proteins which causes increased lens yellowing.

Genetic studies of variation in Rayleigh and photometric matches in normal trichromats.

The inheritance of Rayleigh match midpoints and photometric matches (551-667 nm) was studied in observers with normal color vision. An analysis was performed to evaluate whether the measured interobserver variations in these two traits were consistent with single gene allelic variation, polygenic variation, or environmental factors. A bipartite 2 deg field and a computerized tracking method were used to obtain Rayleigh matches; a new photometric technique, termed heterochromatic modulation photometry (HMP), was used to obtain photometric matches. Data were collected from 72 nonrelated males to determine distribution characteristics for the normal population. The distributions were analyzed for evidence of multimodality and the results indicated that the distributions for Rayleigh match midpoints and HMP matches obtained in this study were unimodal and symmetrical. Data from 52 observers from 5 families were used to study the transmission of the two traits in pedigrees. Statistical analysis of the pedigree data suggested that the major source of variations for Rayleigh match midpoints and for HMP matches were each due to allelic variation at single gene loci; that is, each may be determined by a single gene. Results were inconclusive as to whether variation in the two traits could be determined by the same gene.

Lumbar disk compliance and degeneration.

Comparison between 242 intradiscal pressure/volume recordings and corresponding diskograms (performed at the same occasion) has shown a significant (p less than 0.01) correlation between disk compliance and the degree of diskographic degeneration. Intradiscal pressure/volume testing is a simple, reliable, and risk-free procedure that should precede every diskogram and be incorporated into the preoperative diagnostic routine of patients undergoing chemonucleolysis or percutaneous diskectomy.

[Initial experiences with implanted drug pumps for continuous intrathecal calcitonin therapy in therapy-resistant pain]. / Erste Erfahrungen mit implantierten Medikamentenpumpen zur kontinuierlichen intrathekalen Calcitonintherapie bei therapieresistenten Schmerzen.

The hormone calcitonin has proved itself for some years in the treatment of chronic pain syndromes. In addition to its known influence on calcium exchange it gives vise to an analgesic effect within the central nervous system and this follows systemic administration or after bolus intrathecal injection. Two patients with chronic non malignant pain are presented in whom continuous delivery pumps have been used for intrathecal Lachs-Calcitonin (Karil, Fa. Sandoz).

Periradicular therapy in lumbar radicular syndromes: methodology and results.

Periradicular therapy (PRT) has become popular in the treatment of lumbar radicular complaints, both primary, due to disc herniations (Group 1), and postoperative, following disc surgery (Group 2). However, hitherto reported data on 'periradicular injections' are more of a technical nature. The present study was designed to evaluate the therapeutic success of CT- versus fluoroscope-guided periradicular injections of local anaesthetics and corticoids, and to investigate the impact of imaging procedures on the results. We report on 80 patients who underwent CT-guided (n = 40) or fluoroscope-guided (n = 40) PRT for lumbar radicular irritation since April 1993. Forty patients had primary nerve root irritation due to disc protrusion, and 40 suffered from postoperative epidural fibrosis. Follow-up consisted in a clinical examination and an interview one day after each injection as well as 1 and 6 months later. Assessment was based on a score taking into account the clinical findings, the patient's complaints, and the patient's evaluation. Six months following treatment there was a significant reduction of ischialgia in both Groups 1 and 2 (p < 0.001). However, the results were significantly poorer in Group 2 (postoperative). Among the patients not operated on, those who underwent CT-guided injections had a significantly better outcome (p < 0.001). PRT had no significant influence on low back pain or pseudoradicular syndromes. The improvement of sensory disturbances achieved by both CT- and fluoroscope-guided injections in patients not previously submitted to surgery is statistically significant (p < 0.05). As compared to Group 1 (no surgery), the positive effects in patients of Group 2 were of significantly shorter duration (p < 0.05). Motor deficits were not influenced by the treatment. Long-term follow-up shows that there is no positive effect in those patients in whom the first two PRT attempts had failed. Thus, PRT represents a useful long-term therapeutic alternative for lumbar radicular syndromes, particularly when due to primary discogenic compression. CT-guided injection is superior to fluoroscope-assisted treatment for both its visualization and its longer-lasting effect.

Aging of the human lens.

The optical density of the human lens changes during life. Literature concerning both the spectral density function and the rate of such changes is reviewed. Analysis indicates that two components govern the spectral lens density function, with one increasing gradually during life. The average lens density increases linearly at 400 nm by 0.12 density unit per decade between the ages of 20 and 60 and by 0.40 density unit per decade above age 60. A tabulation of the two components of the average 32-yr old lens is given, as are equations to derive the average spectral lens density functions for observers aged 20-80.

Heterochromatic modulation photometry.

Heterochromatic modulation photometry is a method for obtaining equiluminance for a pair of heterochromatic lights presented in temporal alternation. A series of fixed standard luminance/test luminance ratios are presented, and at each ratio the modulation depth of the pair is reduced in tandem until the observer reports that flicker disappears. The data can be described by a luminance contrast template that appears V shaped when plotted on log-log coordinates. In the fitting of individual data, a free vertical scaling factor reflects the observer's sensitivity to luminance modulation and a free horizontal scaling factor reflects the observer's similarity in spectral sensitivity to the CIE standard observer. Data for red/green flicker photometric matches demonstrate the technique. Heterochromatic modulation photometry offers several advantages over flicker photometry: (1) a single fixed perceptual transition occurs on each trial series, namely, the transition from flicker to steady, and (2) luminance matches can be obtained at fixed frequencies at a number of luminance levels. The same procedure can be applied to the measurement of the minimally distinct border and to the identification of tritan pairs (stimulus pairs that differ only in their stimulation of short-wavelength-sensitive cones).