Cytotoxic effects of antiproliferative agents on human retinal glial cells in vitro

Purpose: Proliferative vitreoretinopathy (PVR) is characterizedby the formation of cellular membranes on the detached retina and also in the vitreous. Glial cellscan be found in epiretinal and subretinal membranes from eyes with PVR, proliferative diabeticretinopathy (PDR), idiopathic macular pucker, uveitis and other diseases affecting theretina. Proliferation and contraction of glial cells appears to play a role in the pathogenesisof PVR. This study is designed to inspect the effectiveness of harringtonine, as well as colchicine,daunomycin and fluorouracil, against cellular proliferation of cultured human retinal glial cellsthat might be involved in the retinal and/or vitreous proliferation. Methods: Cultures of human retinal glial cells were preparedusing the enzyme digesting method. Cells that had been in culture for 2–5 passages were usedin this study. Harringtonine (0.063 g/ml 2.0 g/ml), colchicines(0.5 g/ml 16.0 g/ml), daunomycin (0.1 g/ml 3.2 g/ml) and 5-fluorouracil(0.5 g/ml 16.0 g/ml) were added to cultures of human retinal glial cellsand the proliferation rates of the cells were measured by the MTT method. Results: Harringtonine at the dosage of 0.063 g/mlinduced suppression of cellular growth, but the changes were not statistically significant (p > 0.05).At a dosage ranging from 0.125 g/ml to 2.0 g/ml, harringtonine significantly suppressedcellular growth according to the test (p < 0.01). Likewise, other antiproliferativeagents inhibited cellular growth significantly at a dosage from 1.0 g/ml to 16.0 g/ml(colchicine), 0.2 g/ml to 3.2 g/ml (daunomycin) and 1.0 g/ml to 16.0 g/ml(5-fluorouracil), but not at 0.5 g/ml (colchicine), 0.1 g/ml (daunomycin) and0.5 g/ml (5-fluorouracil). The ID₅₀ were 0.33 g/ml (harringtonine), 3.11 g/ml (colchicine), 0.79 g/ml (daunomycin) and 5.23 g/ml (5-fluorouracil), respectively.Conclusions: Harringtonine was extremely effective ininhibiting human retinal glial cell proliferation, like other antiproliferative drugs such as colchicine,daunomycin and 5-fluorouracil. Harringtonine, therefore, may be a candidate for further studies regardingthe treatment of experimental PVR.     

Retinal toxicity and ocular kinetics of 1-β-D-arabinofuranosyl-E-5-(2-bromovinyl)uracil in rabbits

The intraocular penetration of 1--d-arabinofuranosyl-E-5-(2-bromovinyl)uracil (BV-araU), a new antiviral drug, after oral administration, the effects of non-toxic intravitreal doses of BV-araU, and the intraocular kinetics of BV-araU after intraocular injection were studied in rabbits. The intravitreal penetration of BV-araU after oral administration was very poor: 0.11 ± 0.13 g/ml and 0.20 ±0.02 g/ml respectively in albino and pigmented rabbits 2 h after 30 mg/kg. An intravitreal injection of 200 g BV-araU caused transient electroretinographic (ERG) changes, whereas a 100-g injection and intravitreal irrigation with 20 g/ml BV-araU caused no ERG and histologic changes over the 4-week follow-up period. The half-life of the intravitreal concentration of BV-araU after an intravitreal injection was short (2.4 h). The results suggest that an intravitreal injection of 100 g BV-araU or an intravitreal irrigating solution containing 20 g/ml BV-araU is nontoxic to the retina and may be used for treatment of retinitis caused by varicella-zoster virus or herpes simplex virus type 1.     

Lamellar excimer laser keratoplasty: Reproducible photoablation of corneal tissue

We examined the depth of ablation of the recipient bed with different counts of oscillations of excimer laser beam, to determine the correlation between planned and real depth. The ablation rate per oscillation was tested preoperatively by blackened photographic paper of defined thickness and thus was calculated to be 5 m. Forty pig eyes were used for the first study. Each eight eyes were ablated in the planned depth 100 m, 200 m, 300 m, 400 m and 500 m. The corneal thickness was measured with an ultrasonic pachymeter before and after the procedure. The depth measured after the photoablation was 99.4 ± 36.4 m for 100 m planned depth, 186.7 ± 55.3 m for 200 m, 298.4 ± 68.5 m for 300 m, 373.9 ± 65.7 m for 400 m and 480.1 ± 59.3 m for 500 m. Comparing the depth measured after the photoablation to planned depth, there was a significant correlation (correlation coefficient: R = 0.93; p < 0.0001). Five other corneas trephinated from pig cadaver eyes were ablated from the endothelial side to the desired thickness (100 to 500 m) of lamellar graft. In a second step a donor mask was placed onto the cornea and a laser light spot was led until perforating on all sides. The lamellar keratoplasty was completed by suturing the corneal graft into the bed. Macroscopic and microscopic examination of sutured eyes after fixation showed a good fit of wound margins and stromal interface. These results indicate that excimer laser is useful for reproducible corneal photoablation in lamellar keratoplasty.     

Effect of oxygen on relaxation of retinal pericytes by sodium nitroprusside

Background: This study addresses whether oxygen modulates the relaxation induced in retinal pericytes by sodium nitroprusside (SNP), a nitric oxide (NO) donor that stimulates the NO/guanylate cyclase pathway. Methods:Bovine retinal pericytes were cultured on silicone. On the silicone surface, basal pericyte contractile tone induces wrinkles. Drug-induced changes in pericyte contractile tone were assessed by changes in the number of wrinkles. The effects of 100% nitrogen (hypoxia) and 100% oxygen (hyperoxia) were studied on: (a) the basal tone of quiescent pericytes, (b) the relaxation to 3 and 10 M SNP or 1 M forskolin, and (c) the recontraction that followed the washout of 3 M SNP or 1 M forskolin. Results: Neither hypoxia nor hyperoxia had any apparent influence on pericyte basal tone, on forskolin-induced relaxation, or on pericyte recontraction after a forskolin-induced relaxation. In hypoxia, relaxations to SNP 3 M (P<0.05) and 10 M (P<0.01) were significantly more pronounced than in hyperoxia. Hypoxia also reduced the recontraction after an SNP-induced relaxation (P<0.001). Conclusion: Oxygen modulates the relaxation of bovine retinal pericytes evoked by SNP (guanylate cyclase-mediated), but not the relaxation induced by forskolin (adenylate cyclase-mediated). These results suggest that in the retinal capillary circulation an interaction between oxygen and the NO/guanylate cyclase pathway modulates pericyte tone, and thus potentially blood flow.     

Contact diode laser: High power application through fiberoptic cutting tips

Diode laser energy has been applied through a fiberoptic probe using a power setting of 2.5 watts (W) in the continuous mode. In this study we employed high-power diode laser energy (4 to 12 W, continuous wave) to incise ocular tissue through a fiberoptic probe using 100m and 300m tips. The retina was photocoagulated with a 300m orb tip. No bleeding occurred at the incision sites. Histologic evaluation revealed coagulation into the healthy tissue ranging from 10 to 50m.     

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.     

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.     

Toxicity of 1-(β-d-arabinofuranosyl)cytosine after intravitreal injection in the rabbit eye

The retinal toxicity of intravitreally injected 1-(-d-arabinofuranosyl)cytosine (cytarabine) was examined in 7 chinchilla rabbits to determine if cytarabine can be used as local therapy for vitreoretinal non-Hodgkin's lymphoma. Fractionated dose of 600 g, 1500 g, and 2700 g cytarabine in stabilized saline were given intravitreally in one eye (2 × 300 g, 5 × 300 g, and 3 × 900 g, respectively, with an interval time of 24 h) and stabilized saline in the other eye as control. Toxic effects were evaluated with biomicroscopy, direct ophthalmoscopy, fluorophotometry, electroretinography, light, and electron microscopy. Toxic effects were found with the 1500 g and 2700 g doses only. They consisted of a temporary impairment of the blood retina barrier function for fluorescein as measured by fluorophotometry and an irreversible change of the b-wave in the electroretinograms. No histopathologic changes were seen under the light microscope. Electron microscopic examination showed aberrations in the synaptic pedicles of the photoreceptor cells at a dose of 1500 g cytarabine. The results suggest that the cytarabine dose that is expected to be therapeutic for vitreoretinal non-Hodgkin's lymphoma (about 90 g given in three doses of 30 g) is non-toxic for ocular structures.Correspondence to: J.A. van Best     

In-vivo-Messungen der Breite des Schlemmschen Kanals beim Hydrophthalmus

Zusammenfassung In-vivo-Messungen der Breite des Schlemmschen Kanals ergaben bei 9 Hydrophthalmusaugen einen Mittelwert von 678 m. Die Extremwerte lagen bei 600 m und 800 m. Damit unterscheiden sich diese Werte signifikant von denen, die bei Glaucoma-simplex-Augen in vivo ermittelt worden waren (Mittelwert ¯x: 542 m, Extremwerte 425 m und 625 m).Die Kanalbreite bei Hydrophthalmusaugen nimmt sowohl mit dem Hornhautdurchmesser als auch mit der Höhe des Augeninnendrucks zu.Die Erfolgsaussichten einer Trabekulotomie bei Hydrophthalmusaugen sind offenbar besser, wenn die Kanalbreite unter 650 m liegt. Die Trabekulotomie sollte deshalb so früh wie möglich ausgeführt werden.

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In vivo-measurements of the latitude of Schlemm's canal in buphthalmos

Summary In 9 cases of buphthalmos in vivo-measurements of the latitude of Schlemm's canal gave us a mean value of 678 m. The extreme values ranged between 600 m and 800 m. Therefore these values differ significantly from those measured in vivo in chronic simple glaucoma (¯x: 542 m, extreme values 425 m and 625 m). The latitude of Schlemm's canal correlates with the diameter of cornea and the rise of intra-oculare pressure.In cases of buphthalmos the success of trabeculotomy seems to be better, if the latitude of Schlemm's canal is less than 650 m. Trabeculotomy should therefore be performed as soon as possible.

     

Use of vancomycin in vitrectomy infusion solution and evaluation of retinal toxicity

The retinal toxicity of vancomycin in infusion solution used in vitrectomy and lensectomy was investigated in rabbit eyes by means of electroretinography and histologie study (light microscopy). Concentrations of 8g/ ml, 16g/ml, and 32g/ml of vancomycin in balanced salt solution caused no abnormal ERG or histologic changes. However, ERG amplitude depression and abnormal histologie changes occurred when the concentration of 100g/ml of vancomycin was used.Supported in part by U.S. Public Health Service grants EY07541 and EY02377 from the National Eye Institute, National Institutes of Health, Bethesda, MD.     

Evaluation of toxicity and efficacy of a combination of antineoplastic agents in the prevention of PVR

The retinal toxicity of a combination of antineoplastic drugs in free and liposome-encapsulated form was determined in the rabbit eye. Bleomycin sulfate and 5-fluorouridine were evaluated by clinical observation, electroretinogram, and histological study. Forty-five eyes were injected with combinations of various doses of bleomycin and 5-FUR in free and encapsulated form; 10 eyes served as controls. The nontoxic free dose was found to be 3.5g bleomycin and 150g 5-FUR. Liposome encapsulation increased the nontoxic dose to 4.7g bleomycin and 200g 5-FUR. Four groups of rabbits in which proliferative vitreoretinopathy had been induced were used for the efficacy study; the control group received an injection of PBS; the second group was injected with a combination of 3.5g bleomycin and 150g 5-FUR in free form; the third group was injected with the identical doses in liposome-encapsulated form; and the fourth group received encapsulated bleomycin (4.7g) and 5-FUR (200g). The dose used in Group 4 was significantly more effective (P<0.01) in preventing tractional retinal detachment and marginally more effective (P=0.054) in preventing neovascularization.Supported in part by U.S. Public Health Service grants EY07541 and EY02377 from the National Eye Institute, the National Institutes of Health Services, Bethesda, MD     

Electrophysiologic characteristics of human and rat retinas in vitro

To promote studies on the human retina, we investigated the survival of function in postmortem specimens. Visual pigment has been regenerated in normal human retinas, 5 to 58 hours postmorten, by exposure to retinal isomers in the dark. Levels from 0.1 to 0.41 nmol/ mg protein were reached. Photoresponses were obtained in 9 of 13 retinas: P III maximum amplitudes ranged from 20–398 V and thresholds, taking the criterion amplitude as 3 V, ranged from 8.8–1340 quanta/m ². In three cases, the b-wave was also seen. The P III amplitude vs. log intensity curves gave values of n between 0.6 and 1.0, and (the stimulus intensity for a half maximal response) between 132–3700 quanta/m². Recovery of sensitivity did not always correspond to that of maximum response.     

Die Stereo-Ultrastruktur der Cornealoberfläche bei der Ratte

Zusammenfassung Die dreidimensionale Beschaffenheit der Cornealoberfläche der Ratte wurde mittels des Scanning Electron Microscope und anhand konventioneller elektronenmikroskopischer Schnittpräparate untersucht. Dabei konnte das Vorhandensein von Mikrovilli (0,15 breit, bis 1,0 hoch) und von Mikroplicae (0,1–0,2 breit, 0,3–0,4 hoch, 1–3 lang) nachgewiesen werden. Bei diesen Strukturen dürfte es sich um während der Desquamation entstandene Ausstülpungen der Epithelzellmembran im Bereiche der Desmosomen handeln.

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The stereo ultrastructure of the corneal surface in rat

Summary Combined morphological examination of the corneal surface of rat both with the scanning and the transmission electron microscope reveals two kinds of protrusions covering the polygonal, regularly arranged epithelial cells: Mikrovilli and Mikroplicae; the former being approximatively 0.15 large and up to 1.0 high, the latter being 0.1–0.2 large, 0.3–0.4 high and 1–3 long. These formations are with high probability the remnants of desmosomes having been formed during desquamation.

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Diese Untersuchungen wurden mit Unterstützung des Fonds National suisse de la recherche scientifique (Nr. 5322.3) durchgeführt.     

Effects of β-agonists on b- and c-waves implicit for adrenergic mechanisms in cat retina

Nylidrin (buphenine) is a -adrenergic agonist known to dilate peripheral vessels and used therapeutically in retinal degeneration and glaucoma. We studied retinal function under -agonists in arterially perfused cat eyes and observed a dose-dependent, reversible increase in b-wave amplitude and a decrease in c-wave amplitude in concentrations from 4.5 to 120M. A half maximal response was obtained at 40 to 50M. The optic nerve response to light showed dose-dependent reversible changes under nylidrin. Standing potential, light peak, intraocular pressure, vascular resistance, and diameter of or retinal vessels showed no consistent changes under nylidrin.The effects were inhibited by each of the -blocking agents propranolol, ICI 118, and oxprenolol (in sequence of decreasing potency).Another potent ₂-agonist, clenbuterol, was used to determine the extent to which the responses to nylidrin were due to -receptor-mediated action. Clenbuterol had similar effects on the b-wave and optic nerve response at slightly higher concentrations (30–200 M) but more variable effects on the c-wave.The data are interpreted as functional evidence that -adrenergic mechanisms are involved in retinal signal processing. This concept is corroborated by identification of -adrenergic binding sites in cat retina (Bruinink et al., 1986).     

The effect of body temperature on the murine electroretinogram

Purpose: To study the effect of body temperature on the murine electroretinogram (ERG). Methods: The corneal ERG elicited by a strobe flash from dark-adapted mice was recorded using a saline wick electrode while measuring rectal temperature continuously. The mouse was placed within a cylindrical coil of tubing through which water circulated from a temperature controlled bath. The body temperature of the mouse was changed stepwise between 30 and 37°C. Results: ERGs of approximately normal configuration were recorded at body temperature ranging between 30 and 37°C. The maximum amplitude of the a- and b-waves varied linearly with temperature. The rate of change of b-wave amplitude was about 100 V/degree. At 30°C, maximum b-wave amplitude was about 400 V; at 37°C it was about 1000 V. A change in body temperature produced a rapid change in ERG amplitude. Conclusion: The murine ERG is very sensitive to changes in temperature. In order to monitor the ERG accurately over time, continuous recording of body temperature is essential.     

Die fixation des menschlichen auges

Zusammenfassung Während der Fixation wird ein Fixationsfeld beansprucht im Ausmaße von 100 , d.i. das Bereich der dünnsten und höchsten Zapfen, von 1 Durchmesser. In diesem Fixationsfeld ist der Fixationspunkt der Willkür entzogen. Während der strengen Fixation macht das Auge bekanntlich dreierlei Bewegungen, von denen die schnellen ebenfalls in einem Feld von 100 Durchmesser liegen. Das maculopapilläre Bündel führt die Erregungen aus dem auch in Bezug auf das Ableitungssystem ausgezeichneten Fixationsfeld ab. Die Sehschärfe unterschreitet weit die Grenze von 1 , was auf die Synapsenfunktionen der Retina, des Corpus geniculatum laterale und auf die cortikalen Bezirke zurückgeführt wird.

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Summary During fixation a fixation-field of 100 diameter is required, corresponding to the area of the thinnest and longest cones of 1 diameter. Within this fixation-field the position of the fixation point is involuntary and at random. The fast component of the three eye movements during fixation also covers a field of 100 diameter. Impulses from this field are conducted via the maculo-papillary bundle. The visual acuity is far below the limit of 1 ; this is attributed to the synaptic function of the retina, the lateral geniculate body and the cortical areas.

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Résumé Pendant la fixation un champ de 100 se trouve occupé, c'est-à-dire la région des cônes les plus hauts et les plus minces, qui ont pour diamètre 1 . Dans le champ de fixation le point de fixation n'est plus soumis à la volonté. Pendant la fixation précise l'oeil fait trois sortes de mouvements; les plus rapides d'entre eux intéressent aussi un champ d'un diamètre de 100 . Le faisceau papillo-maculaire conduit les influx nerveux hors du champ de fixation. L'acuité visuelle descend bien en-dessous de 1 . Ce fait est attribué aux fonctions synaptiques de la rétine, du corps genouillé externe et des régions corticales.

     

Mathematical consideration of aqueous outflow after Trabeculo-Electropuncture (TEP)

Summary The obtainable postoperative intraocular pressure following a TEP in a glaucoma patient with an intraocular pressure of 30 mm Hg is calculated in accordance with the concept that there is no outflow of aqueous humor along Schlemm's canal. If aqueous humor reaches all collector channel openings in the surgical area without resistance, the postoperative intraocular pressure reads 14.75 mm Hg. This intraocular pressure is obtained at a point when a collector channel of 1 mm length and of 32 m in diameter or two collector channels of 27 in diameter or five collector channels of 22 in diameter establish connection with the trabecular opening.

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Zusammenfassung Der erreichbare postoperative Augendruck nach einer TEP bei einem Glaukompatienten mit dem Augendruck von 30 mm Hg wird unter der Vorstellung berechnet, daß es keinen Kammerwasserabfluß im Schlemmschen Kanal entlang gibt. Wenn das Kammerwasser alle Collector channel Öffnungen im Operationsgebiet ohne Widerstand erreicht, dann ist der postoperative Augendruck 14,75 mm Hg. Dieser intraokulare Druck wird dann erreicht, wenn ein Collector channel von 1 mm Länge und einem Durchmesser von 32 oder zwei Collector channel mit einem Durchmesser von 27 oder fünf Collector channel mit einem Durchmesser von 22 mit der Trabekelöffnung in Verbindung stehen.

     

Increased release of tenascin in tear fluid after photorefractive keratectomy

Background: Extracellular matrix protein tenascin (TN) is expressed in the anterior stroma during corneal wound healing. In this study we analysed TN release in tear fluid after photorefractive keratectomy (PRK). Methods: Tear fluid TN concentrations of ten PRK patients were measured with an immunoassay. Tear fluids were collected preoperatively and 1, 2 and 7 days after PRK. The tear fluid collection time and the volume of tears collected were registered. Because tear fluid flow was greatly increased postoperatively, tear fluid flow-corrected release (TN flux) was calculated. Results: The tear fluid flow was 4.50±0.94 l/min (mean±SEM) preoperatively, 55.48±16.70 l/min (P<0.01) on the 1st, 33.91±7.91 l/min (P<0.01) on the 2nd, and 13.79±5.49 l/min (P>0.05) on the 7th postoperative day. The preoperative TN concentration was 0.85±0.20 g/ml. On the 1st postoperative day it decreased to 0.37±0.17 g/ml (P>0.05), most likely due to the dilution effect caused by hypersecretion after PRK. The TN concentration was 0.67±0.12 g/ml (P>0.05) on the 2nd and 0.78±0.15 g/ml (P>0.05) on the 7th postoperative day. The preoperative TN flux was 5.23±1.88 ng/min. On the 1st and 2nd postoperative days the TN flux was 14.40±4.99 ng/min (P<0.05) and 22.66±6.I2 ng/min (P<0.05), respectively. On the 7th postoperative day a tendency towards decreased flux (14.00±6.02 ng/min, P>0.05) was observed. Conclusion: Although there is a minor decrease in TN concentration after PRK due to increased tear fluid flow, a significant increase in TN flux was observed. Complete reepithelialization of the ablated area was observed in all eyes at the follow-up visit on postoperative day 7.     

Effects of norfloxacin on the retina in rabbits

Background: Fluoroquinolones have a strong affinity with melanin, and their ocular effects have been reevaluated. Norfloxacin, one of the fluoroquinolones, has broad-spectrum activity against aerobic gram-positive and gram-negative bacteria. We examined the retinal toxicity and intraocular pharmacokinetics of intravitreal norfloxacin in rabbits. Methods: Twenty-three albino and 23 pigmented rabbits were divided into three groups to evaluate retinal toxicity and two groups to investigate the intraocular pharmacokinetics. Each of these five groups was further divided into two subgroups (albino rabbits and pigmented rabbits). Results: With 500 Etg norfloxacin, the oscillatory potential of the electroretinogram was transiently and selectively deteriorated in albino and pigmented rabbits, whereas the electroretinogram remained unchanged with 50 g in pigmented rabbits. No changes were observed in the visual evoked potential or on histology of the retina 7 days after an intravitreal injection of 50 or 500 ltg norfloxacin. The electroretinogram and the retinal histology became abnormal 7 days after four intravitreal injections of 500 g norfloxacin at 7-day intervals. As regards the intraocular pharmacokinetics after an intravitreal injection, the norfloxacin concentration in the chorioretina was as high as that in the vitreous 3 h after injection and was much higher than that in the vitreous 7 days after injection. Similar results were obtained after multiple injections. Conclusion: These results indicate a high concentration of norfloxacin in the melanin-containing ocular tissues.     

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.