Morphological and functional changes of the macula after vitrectomy and creation of posterior vitreous detachment in eyes with diabetic macular edema

The purpose of this study was to determine the morphological and functional changes in the macula after pars plana vitrectomy with the creation of a posterior vitreous detachment in eyes with diabetic macular edema (DME). A simple posterior vitreous detachment was created during pars plana vitrectomy accompanied by simultaneous cataract surgery in 19 eyes of 17 patients with DME. The visual acuity (log MAR units), multifocal electroretinograms (mfERGs), and optical coherence tomographically (OCT)-determined foveal thickness were determined preoperatively and at 6 months postoperatively. The median preoperative log MAR visual acuity was 0.7 (20/100; range, 0.3–1.1), and it improved significantly to 0.4 (20/50; range, 0.15–1.0) postoperatively (p = 0.016). The median foveal thickness was 510 (range, 194–800) m preoperatively and was significantly reduced to 201 (range, 60–631) m postoperatively (p =0.0002). The median of response density of the mfERGs in the macular area was 6.3 nV/deg² (range, 2.8–14.8) preoperatively, and 6.1 nV/deg² (range, 2.4–14.3) postoperatively, a non-significant change (p = 0.27). The median of peak latency of the macular response was 30.0 ms (range, 25.0–44.2) preoperatively and it decreased significantly to 28.3 ms (range, 26.7–35.0) postoperatively (p = 0.003). In conclusion, vitrectomy with the creation of a PVD in eyes with DME improved the visual acuity and foveal thickness significantly. In addition, a decrease of the peak latency of the macular mfERGs suggested an improvement of the physiological function of the macula although the amplitude of the mfERGs was not changed significantly.     

Human conjunctival surface mucins: A quantitative study of normal and diseased (KCS) tissue

The architecture and distribution of surface mucins were studied qualitatively and quantitatively by transmission electron microscopy in ruthenium red stained biopsies of the human conjunctiva. Six control specimens were compared with three from early keratoconjunctivitis sicca (KCS) and with three specimens from severe KCS cases. The area of the ruthenium red/Os04/mucin reaction product on the conjunctival epithelial surface was measured by image analysis and the values were expressed in m² per m length of epithelium. The total area of surface mucins was differentiated from the narrow zone of mucins in close contact with the microplicae. The value for total mucins in two cases of early KCS was higher (0.4 m²/m) than the control range (0.1–0.3 m²/m) due to the presence of large clumps of mucins on the surface. The values for microplical mucins in early and severe KCS were within the control range, but were an overestimate owing to the presence of abnormal structures, e.g. vesicles, and abnormal clumps on the surface. This morphometric technique has limitations, but with appropriate material it might be a useful tool for the identification of conjunctival surface mucins.This paper was presented in part at the Eighth Annual Meeting of the European Club for Ophthalmic Fine Structure in West Berlin on 28th, 29th March, 1980     

The negative response of the flash electroretinogram in glaucoma

The existence of a negative ERG component following the b-wave has been known for a long time. Recently, in unilateral macaque experimental glaucoma, a negative response in flash electroretinograms under scotopic as well as photopic conditions has been shown to be greatly reduced or absent compared to the healthy fellow eye. The aim of this pilot study was to test whether a late negative electroretinogram component is reduced also in human glaucoma patients under different stimulus conditions. Dark-adapted ganzfeld flash electroretinograms were recorded after 30 min of dark using two test conditions, obtained as optimal in pilot studies on controls. Under the scotopic condition I white Xenon-flashes of intensity 0.53 Log photopic Td s were presented on a low white background of 1.38 Log scotopic Td. Under the more photopic condition II orange flashes of intensity –0.37 Log photopic Td s were presented on a blue-adapting background of 2.5 Log scotopic Td. Nine controls and 18 patients with advanced glaucoma were analyzed. The amplitude of the negative response was not significantly reduced in glaucoma patients (condition I: –28.5±23.7 V; condition II: –25.2±19.7 V) compared to controls (condition I: –41.4±36.6 V; condition II: –31.3±26.2 V). The peak latency of the responses under condition I and II did not differ significantly between patients and controls. Thus, the late negative electroretinogram component in ganzfeld flash electroretinograms obtained under scotopic and more photopic conditions does not seem to distinguish as easy between human controls and glaucoma patients as animal experiments suggest.     

Functional imaging of the retinal microvasculature by Scanning Laser Doppler Flowmetry

Purpose: to image functionally perfused retinal vessels and to assess quantitatively the intercapillary space of the retinal microvasculature.Method: The base offunctional imaging and the quantitative assessment of the retinal vasculature is the two-dimensional map of the retina encoded by the laser Doppler frequency shift. By Scanning Laser Doppler Flowmetry (HRF. Heidelberg Engineering) the laser Doppler frequency shift of 16.384 retinal sites (256 pixels × 64 lines, spatial resolution10 m) of a retinal area of 2.7 × 0.7 mm was gained. The image processing was performed by a recently described algorithm (AFFPIA). Using the data of the laser Doppler frequency shift of every retinal site, a color-coded retinal image was establishedshowing perfused vessels and capillaries. By automatic pattern analysis of this image vessels and capillaries were identified and segmented. Based on this image the distances in [m] of every retinal site to the next vessel or capillary were calculated ("distanceto next capillary'). The functional imaging of the retinal perfusion was demonstrated in (1) normal retina, (2) retinal arterial occlusion, and (3) proliferative retinopathy. Intraobserverreliability of the quantitative assessment of the parameter ``distance to next capillary' was estimated by measuring 10 eyes of 10 subjects at 5 different days by one observer. Interobserver reliability of the quantitative assessment was evaluated by analysing10 perfusion maps by 5 different operators. In 93 eyes of 71 normal subjects (mean age 40.4 15 years) the juxtapapillary retina was quantitatively evaluated.Results: Qualitative evaluation: The functional images of the retinal perfusion of eyes with normal retina, with retinal arterial occlusion, and with proliferative retinopathy correspondedwell with the fluorescein angiography. Perfused vessels and capillaries became visible in a high local resolution. Quantititative assessment: The coefficient of reliability of the introobserver and interobserver reproducibility of the parameter ``mean distance to next capillary' was 0.74, and 0.95, respectively. The quantitative assessment of the perfusion showed that the major part of the retinal sites (>700%) had distancesto the next capillary lower than 30 m 46% of the retinal area had distances to the next capillary from 0–20 lm 26% of the retina had distances from 20–30 m, 12% of the retina had distances from 30–40 m 7% of the retina had distances from 40–50 m, 4% of the retina had distances from 50–60 m, and 4% of the retinal sites showed distances to the next capillary greater than 60 m. The mean distance tothe next capillary or vessel was calculated with 21 ± 6.5 m.Conclusion: By non-invasive Scanning Laser Doppler Flowmetry in combination with adequate softwareit is possible to perform a functional imaging of the retinal vasculature and to measure all index for the functional density of retinal capillaries and vessels.     

Rod and cone contribution to adaptation processes in cat retinal ganglion cells

Extracellular ganglion cell responses were recorded to investigate mechanisms of light adaptation. Monochromatic test spots (575 nm) were projected onto the receptive field center of off-center cells and superimposed on a steady blue-green Ganzfeld background (Schott Filter BG 28), the strength of which was increased in steps of 0.5 log units to adapt rods. Response vs. log intensity functions were determined over a range of 7 log units of test light irradiance at each background level. At higher adaptation levels response thresholds followed the typical Weber function. Surprisingly at lower adaptation levels the sensitivity of the cell increased by about 0.7 log units, most markedly in a range of 1 log unit of moderate light adaptation when the background was changed from dark to the dimmest detectable background (10^–5lm/m²). In the dark-adapted state a small off-response of long latency (40–100ms at 10² quanta · s^–1 · m^–2) is observed at low rod stimulating test light irradiances. A transition to a cone-dominated transient response of 2 to 5 ms duration occurred at high intensities (10⁵ quanta · s^–1 · m²). At mesopic levels the two responses seem to cancel each other, rendering a delayed off-response that is probably the result of rod-cone interaction. As in psychophysics, saturation can be observed at very high background intensities (10⁶ quanta · s^–1 m^–2). These data suggest interactions between rods and cones that determine the sensitivity of cat retinal ganglion cells at low levels of adaptation for suprathreshold stimuli.     

Hemodynamic parameter estimation from ocular fluorescein angiograms

Background: A method is proposed for parameterizing choroidal blood flow from fluorescein angiograms. Methods: After digitizing and aligning the angiographic sequence, the intensity build-up curves of fluorescence are analysed per pixel (approx. 10 m in fundo). Two models are compared. A one-compartment model predicts an exponential build-up curve, from which the following parameters are estimated: maximum fluorescence, dye appearance time and local perfusion rate (reciprocal of the time constant of the exponential). To account for the contribution of the systemic circulation to the shape of the build-up curve, a two-compartment model is used which predicts a bi-exponential curve. Results: Introduction of the second (systemic) compartment resulted in a significant improvement of fit in 37 of 48 patients studied. The rate constants of the systemic compartment found were mainly in the range of 0.30–1.00 s^–1. Conclusion: For the individual patient, the local perfusion rates may vary strongly, with lower perfusion rates possibly being of prognostic value for ocular diseases such as glaucoma or diabetic retinopathy.     

Ultrasound biomicroscopic analysis of the effect of pilocarpine on the anterior chamber angle

Background: This study was carried out to determine the effects of pilocarpine on the anterior chamber angle in healthy volunteers. Methods: We measured changes in anterior chamber depth (ACD), trabecular-iris angle (TIA), angle opening distance at 250 and 500 m from the scleral spur (AOD250 and AOD500), and iris thickness using ultrasound biomicroscopy in 48 eyes of 48 normal volunteers (ages 18–57 years, mean 34.8 years) before and 1 h after instillation of 2% pilocarpine. Results: Pilocarpine altered the TIA by –18.6° to + 10.5° (mean –4.16°), and change in the TIA increased significantly and linearly in relation with decrease in the pretreatment TIA (r = 0.929). Pilocarpine altered AOD250 change by –136 to +94 m (mean –38 m) and AOD500 by –151 to +157 m (mean –42 m); changes in the AOD250 and AOD500 were significantly correlated to the pretreatment AOD250 and AOD500 values, respectively (r = 0.923 andr = 0.896, respectively). The pilocarpine-induced change in the ACD showed a linear relationship to the pretreatment ACD (r = 0.887). The changes in the TIA, AOD250 and AOD500 showed greater increases in association with lower pretreatment ACD (r = 0.848,r = 0.891,r = 0.842) and smaller change in the ACD (r = 0.834,r = 0.839,r = 0.812). Conclusions: The response of the anterior chamber angle to pilocarpine, narrowing or widening, depended on its pretreatment state. The ability to predict the pilocarpine-induced change in the angle before the instillation of pilocarpine would be helpful in treating patients with glaucoma.     

[3H]-Dopamine release from the rabbit retina

[³H]-Dopamine was found to be released from the rabbit retina in vitro by light stimulation, by 40 mM K +, and by -MSH (-Melanocyte-Stimulating Hormone) down to about 10^–7 M. The effect of -MSH was dose-dependent. A number of known and putative retinal neurotransmitters and agonists (GABA, muscimol, glutamic acid, kainic acid, glycine, and carbachol, all 10^–4 M) were without significant effect. The results show that it is unlikely that there are excitatory receptors on the retinal dopaminergic neurons to any of the conventional transmitters. Further, -MSH seems of interest as a possible neuroactive retinal substance, which has previously not been suspected.     

Effects of intravitreal perfusion with dopamine in different concentrations on the DC electroretinogram and the standing potential of the albino rabbit eye

The direct current electroretinogram and the standing potential were recorded from both eyes of 23 albino rabbits during intraocular perfusion of one of the eyes, which was vitrectomized, with a physiologic reference solution (PHS). PHS was then replaced by a test solution containing dopamine dissolved in PHS. The fluids were subsequently alternated (PHS-dopamine-PHS). During irrigation with 0.25–0.5 mM dopamine (11 rabbits) the c-wave amplitude was 140% higher (p < 0.001) and during irrigation with 25 mM dopamine (6 rabbits) 85% lower (p < 0.01) than it was during the corresponding initial perfusion with PHS. The simultaneously recorded b-wave amplitude was reduced (0.25–0.5 mM: -22%, p < 0.001; 25 mM: - 69%, p < 0.001) and the SP level increased (0.25–0.5 mM: +2375 V, p < 0.01; 25 mM: +2530 V, p < 0.05) compared with the values obtained during the corresponding preceding irrigation with PHS. Thus the changes in the b- and c-wave amplitudes during perfusion with dopamine were dependent on the concentration of the drug. In the contralateral control eye (23 rabbits) the c-wave amplitude was 21% higher (p < 0.001), the b-wave amplitude 14% higher (p < 0.001) and the standing potential 1007 V higher (p < 0.001) during intravitreal perfusion with dopamine in the other eye than during the preceding irrigation with PHS in that eye, possibly as a result of increasing dark adaptation.     

„Aberrante“ Ganglienzellen in der Wurzel des Nervus oculomotorius des Menschen

Zusammenfassung 56 Nn. oculomotorii von 37 Erwachsenen (mittleres Alter 66 Jahre) wurden untersucht. In 25 der 56 Nerven (44,6%) bzw. bei 19 der 37 Erwachsenen (51%) wurden insgesamt 243 Ganglienzellen in der Nervenwurzel gefunden. Der mittlere Durchmesser von 100 Zellen betrug 43.7 (range: 26,8–69,8 ; größte Frequenz bei 35–45 ). Histologisch ähneln sie den sensiblen Zellen eines Spinalganglions. Es wird die Frage aufgeworfen, ob es sich um aberrante Ganglienzellen oder ein Zellsystem handelt.Der Befund eines sensiblen Ganglion mit 46 Ganglienzellen im Verlauf des N. trochlearis wird erwähnt.

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Aberrant ganglion cells in the human ocullomotor nerve

Summary 56 oculomotor nerves of 37 adult men (mean age 66 years) were examined. A total amount of 243 nerve cells were counted in 25 nerves (44.6%) that is to say in 19 men (51%). The mean diameter of 100 cells was 43.7 (range: 26.8–69.8 ,). The diameter of most of the cells fell between 35 to 45 . Histologically they look like sensory cells of a spinal ganglion. The question arises, whether these neurones represent aberrant cells or an independent neuronal grouping.The finding of a sensory ganglion in the course of the trochlear nerve with 46 nerve cells in it is mentioned.

     

Distribution of calcium and sulphur in the blue-light-exposed rat retina

Background: Blue-light exposure inhibits cytochrome oxidase and may therefore inhibit retinal metabolism. The reduced metabolism decreases the extrusion of calcium from the photoreceptor cell. Overload of calcium is proposed as one of the factors that lead to photoreceptor degeneration after light exposure. The light-induced photoreceptor degeneration can be ameliorated by calcium overload blocker. In the present study the calcium concentration was measured in the inner and outer segment layer of the rat retina. Methods: Six eyes were exposed to blue (404 nm) light at a retinal dose of 380 kJ/m². Five eyes served as the control group. The calcium and sulphur distributions were measured with a nuclear microprobe in the freeze-dried rat retina. The proton beam size was 12 × 12 m and the energy of the protons was 2.55 MeV The calcium concentration was calculated using sulphur as a reference. Results: The level of calcium per milligram sulphur was 21 g (range 17–23 g) in the inner segment of the control retina. It increased to 62 g/mg sulphur (range 52–67 g) and 61 g/mg sulphur (range 58–66 g) 1 h and 12 h after blue-light exposure, respectively. Conclusion: The findings of the present study support the idea that accumulation of calcium in the inner segment layer is one of the factors that cause photoreceptor degeneration.     

Morphometric analysis of the optic disc surface

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 <- – 17.79 (–1 × 10^–2 mm); glaucoma group: SD > – 17.79 (– 1 × 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.     

Ciliary body toxicity of cyclosporin A and octreotide acetate in rabbit eyes: a comparison with mitomycin C and 5-fluorouracil

Purpose To compare the toxicities of cyclosporin A, octreotide acetate, mitomycin C and 5-fluorouracil to the ciliary body.Method We applied sponges soaked in these compounds to the open scleras of rabbit eyes. Histopathological specimens were obtained from the operation site and at 180° from it on the 14th day after surgery.Results Mean ciliary epithelial thickness in the study groups was as follows: 12.29±2.69 m in group 1 (mitomycin C), 13.85±4.56 m in group 2 (5-fluorouracil), 17.71±3.09 m in group 3 (cyclosporin A), 11.64±2.92 m in group 4 (octreotide acetate), 11.92±2.89 m in group 5 (topically applied octreotide acetate) and 21.85±4.29 m in group 6 (control). The ciliary epithelial thickness in groups 1, 2, 4 and 5 was statistically different from that in the control group. Intracellular vacuolisation and degenerative changes of the non-pigmented epithelium, and pigment loss of the pigmented epithelium, were found mostly in group 1 and moderately in group 2 and 3.Conclusion Octreotide acetate and cyclosporin A are less toxic alternatives to mitomycin C and 5-fluorouracil in glaucoma filtration surgery.     

Immunohistochemical study of leucine-enkephalin and its secretory effects in the isolated pig lacrimal gland

Background: In our previous studies immunohistochemical studies have demonstrated the presence of leucine-enkephalin (Leu-Enk) in the intrinsic nerves of the pig lacrimal gland, which are discernible in the interlobular and interacinar areas from where branches that innervate the acinar tissues are sent. Since the intrinsic nerves have been shown to contain Leu-Enk, this study aimed to investigate the secretory effects of this neuropeptide in isolated segments of the pig lacrimal gland and to reconfirm its presence in the neuronal tissue of the lacrimal gland. Methods: Leu-Enk was identified using immunohistochemical techniques, while total protein output was measured in the effluent samples by an automated on-line colorimetric method. The Ca²⁺ and Mg²+ concentrations in the effluent samples were determined using an atomic absorbance spectrophotometer. Results: Leu-Enk (10^–12 – 10^–7 M) evoked marked increases in total protein output from superfused lacrimal gland segments. The secretory effect of Leu-Enk was not blocked by pretreatment of the tissue with atropine but was substantially reduced by a combination of phentolamine and propranolol. The competitive antagonist, naloxone, has no effect on basal protein output, but when combined with Leu-Enk it caused a significant reduction in total protein output. Combining theophylline (10^–3 M) with Leu-Enk resulted in a marked potentiation of total protein output. In superfused lacrimal gland segments Leu-Enk (10^–8 M) evoked a net efflux of magnesium (Mg²⁺ release) and a net influx of calcium (Ca²⁺ uptake). Conclusion: The results indicated a physiological role for Leu-Enk in the regulation of protein secretion in the pig lacrimal gland.     

Toxicity and efficacy of intravitreal injection of spartanamicin B* in the treatment of Candida endophthalmitis **

Aims/Background: We evaluated the retinal toxicity of spartanamicin B and its efficacy in a rabbit model of Candidal endophthalmitis. Methods: Toxicity. Fourteen albino rabbit eyes were injected intravitreally with spartanamicin B (1, 2, 5, 10, 25, 50, and 100 g) ; 2 eyes received the vehicle alone. Efficacy. Ten rabbit eyes were inoculated with 3000 Candida organisms which caused endophthalmitis in 24 hours. Eight eyes were treated with intravitreal spartanamicin B in doses of 1, 2, 5, or 10 g/0.1 ml; 2 untreated eyes served as controls. Results: Toxicity. The eyes injected with 10 g and the control group eyes exhibited no clinical, histological, or electroretinographic evidence of retinal toxicity. Doses > 10 g caused vitritis. Efficacy. Clinical examination of the treated eyes showed a gradual improvement over 3–6 days; mild opacities remained until day 14. Results of cultures performed 15 days after infection were negative in all treated eyes. Conclusions: Intravitreally injected spartanamicin B (10 g) is nontoxic to the retina, effective against C. albicans in the endophthalmitis model in the rabbit eye and caused no discernible histological changes in the retina.     

Count and density of human retinal photoreceptors

This investigation was directed at determining the count and regional distribution of photoreceptors in the eyes of 21 human cornea donors aged between 2 and 90 years. Mean count of rods was 60 123 000 ±12907000, and mean cone count was 3173000 ± 555000. Determined 40 m away from the foveola, cone density measured 125 500 cones/mm². Extrapolating the distribution curve, cone concentration in the foveal center can be assumed to be about 150 000 cells/mm² to 180 000 cones/mm². Towards the retinal periphery, cone density decreased from 6000 cones/mm² at a distance of 1.5 mm from the fovea to 2500 cells/mm² close to the ora serrata. Comparing different fundus regions, cone concentration was significantly highest in the nasal region. Cone diameter increased from the center towards the periphery. At a distance of 40 m away from the foveola, it measured about 3.3 m, and in the outer retinal regions about 10 m Rod density was highest in a ring-like area at a distance of about 3–5 mm from the foveola with a mean of 72 246 ± 17 295 cells/mm². Rod density peaked at 150 000 rods/mm². It decreased towards the retinal periphery to 30 000–40 000 rods/mm². Rod diameter increased from 3 m at the area with the highest rod density to 5.5 m in the periphery. The hexagonal rod and cone inner segments were regularly arranged in a honey-comb fashion.Supported by the Deutsche Forschungsgemeinschaft (Klinische Forschergruppe Glaukome Na 55/6-1/Jo) Correspondence to: J.B. Jonas     

Effects of vitrectomy and phakectomy on the drainage of the vitreous compartment

Plastic microspheres (7–10 m in diameter), ⁵¹Cr-labeled autologous red blood cells (RBC), and ¹²⁵I-tagged homologous albumin were injected into the vitreous space of vitrectomized phakic and aphakic rabbits. The drainage into the aqueous compartments and blood circulation was assessed. In phakic eyes, there was practically no movement of microspheres and RBC into the anterior chamber over a period of 19 days. In aphakia, vitreous clearance improved but only 1%–3% of labeled RBC appeared in the blood circulation during the first 3–4 days. About 40%–70% of the ¹²⁵I-albumin injected left the eye within 24 h, as compared to 15%–25% in phakic rabbits.Thus, a vitrectomy in phakic eyes does not lead to anterior drainage of intact RBC and even after combined vitrectomy and phakectomy, the drainage of RBC is not complete; the elimination of albumin is greatly enhanced after vitrectomy.

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Zusammenfassung Plastische Mikrokügelchen (7–10 m Durchmesser), ⁵¹Cr-markierte autologe rote Blutzellen (RBC) und ¹²⁵J-markiertes Albumin wurden in den Glaskörperraum vitrektomierter phaker und aphaker Kaninchenaugen injiziert. Die Drainage in Kammerwasserräume und Blutzirkulation wurde beurteilt. In phaken Augen fand sich innerhalb 19 Tage praktisch keine Bewegung von Mikrokügelchen und RBC in die Vorderkammer. In aphaken Augen war die, Clearance' aus dem Glaskörper erhöht, jedoch nur 1–3% der markierten RBC erschienen innerhalb der ersten 3 bis 4 Tage im Blutkreislauf. Etwa 40–70% des injizierten ¹²⁵J-Albumins verließ das Auge innerhalb 24 Stunden, verglichen mit 15–25% bei phaken Kaninchenaugen.Eine Vitrektomie in phaken Augen führt demgemäß nicht zu einer vorderen Drainage intakter RBC, und auch nach kombinierter Vitrektomie und Linsenentfernung ist die Drainage der RBC nicht vollständig; die Eliminierung von Albumin ist nach der Vitrektomie deutlich erhöht.

     

The effect of the water-drinking test on aqueous humor dynamics in healthy volunteers

In 19 healthy volunteers (9 men, 10 women) we studied the effect of drinking 1000 ml of water within 10 min on aqueous humor dynamics. Fluorescein was applied topically five times, 6 h before measurements. All readings were taken during the afternoon. The Wilcoxon signed-rank test was used to evaluate the statistical relevance of the data. Aqueous humor flow was measured 60 min before (F1) and 10 min (F2), 30 min (F3), 60 min (F4) and 90 min (F5) after drinking 11 of water. Flow (mean ± SD) changed as follows: F1, 2.25 ± 1.2 ll/min ; F2, –3.29 ± 3.4 /min (P < 0.0000); F3, 1.69 ± 1.0 gml/min (P=0.007); F4, 2.39±0.9 l/min (P=0.25); F5, 2.64±0.9 l/min (P=0.02). Three to four days later the identical procedure was performed in each individual: F1, 2.06 ± 1.0 l/min F2, –3.12 ± 2.4 l/min (P < 0.0000); F3, 1.09 ± 0.6 l/min (P < 0.0001); F4, 1.76 ± 0.6 l/min (P=0.15); F5, 2.54±0.8 l/min (P=0.01). The correlation coefficient for the left and night eyes (F1–F5, both days) was r=0.85. The mean flow in the 19 healthy volunteers during the afternoon hours was 2.25 ± 1.0 l/min. Water load consistently led to a reflux of unbound fluorescein into the eye about 10 min later. This is documented as a negative flow. Ninety minutes after drinking 1000 ml of water there is a significant increase in flow, which is in contrast to the normal diurnal curve of aqueous humor dynamics. Water load causes hydremia and an increase in episcleral venous pressure. Fluorophotometry together with water load may be useful to study the aqueous humor dynamics in healthy and glaucomatous eyes and eyes with ocular hypertension.     

Über das Vorkommen lichtempfindlicher,fluorescierender Substanzen in verschiedenen Geweben von Rinderaugen

Zusammenfassung und Ergebnisse Papierchromatographisch wurde aus Hornhäuten, Linsen und Netzhäuten von Rindern eine nach denR _f -Werten und UV-Spektren gleiche Substanz isoliert. Sie fluorescierte im alkalischem Medium leuchtend grün, im sauren leuchtend blau. Die Absorptionsmaxima lagen in n/10 Natronlauge bei 258–260 m und bei 400 m und in n/10 Salzsäure bei 258–260 m und bei 360 m. Auffallend war die starke Lichtempfindlichkeit dieser Verbindung. Eine Identifizierung der fluorescierenden Substanz gelang nicht. Auf Grund der gefundenen UV-Spektren und derR _f -Werte in Pteridinlaufmitteln kann vermutet werden, daß es sich um ein Pteridin handeln könnte.Mit 5 Textabbildungen     

Determination of the pseudofacility by fluorophotometry in the human eye

Purpose: Pseudofacility (decrease in aqueous humor flow in response to increase in the intraocular pressure (IOP)) has been evaluated in animals and in humans by a combination of different techniques that seriously alter the ocular physiology, such as the cannulation of the eyeballs, use of radioactive isotopes, perilimbic suction cups or tonography. Very different results have been obtained. Our objective is to relate the value of the aqueous humor flow in humans (as measured by fluorometry) with IOP. In order to obtain the widest range of IOP possible, we have performed this study in both normal as well as glaucoma patients. Methods: 48 eyes were studied, corresponding to 31 subjects (mean age 58 ± 14 years). Of these, 21 corresponded to normal subjects and 27 to glaucoma patients. The aqueous humor flow (F) was determined by fluorophotometry (Protocol of Yablonsky) and the IOP was measured thereafter. Results: The mean value of F was 2.1 ± 0.5 l/min for healthy eyes and 2.2 ± 0.7 l/min for glaucoma-affected eyes. The values were not different (p > 0.1). The mean value of the IOP was 15.3 ±3.1 mmHg in the normal population and 22.1 ± 4.3 mmHg in the glaucoma patients. A linear relationship between F and IOP was found (r = – 0.41, p < 0.05, decrease in F = 0.081 l min^–1 mmHg^–1). Conclusions: The value of the pseudofacility in the humans can be estimated at 0.081 l min^–1 mmHg^–1, which constitutes 27% of the total outflow facility. This figure also makes it possible to estimate the role of the ultrafiltration in blood in the production of the aqueous humor since it is assumed that active secretion is pressure-independent. The results obtained are concordant with a secondary but no unimportant role of the plasmatic ultrafiltration with respect to the active secretion.