Free radical scavenging and antioxidant activity of allopurinol and oxypurinol in experimental lens-induced uveitis

Purpose. In addition to the inhibition of xanthine oxidase, allopurinol is known to act, dependent on the dose, as a free radical scavenger, an antioxidant, and a "scavenger" of hypochlorous acid. This activity was investigated using a model of lens-induced uveitis. Methods. Lipid peroxides (LPO) were determined in aqueous humor and in retinal tissue. Reduced and oxidized glutathione (GSH and GSSG) of the aqueous humor and myeloperoxidase (MPO) activity in the iris-ciliary body complex were analyzed. Allopurinol and oxypurinol concentrations were determined by high-performance liquid chromatography in aqueous humor and retinal tissue of both control eyes and eyes with uveitis. These measurements were performed 6 hours after intravenous application of allopurinol. Results. In lens-induced uveitis, LPO are significantly elevated, GSH is reduced, and GSSG and MPO are increased. A xanthine oxidase inhibition dose (<10 mg/kg body weight) of allopurinol showed no effects on oxidative tissue damage in the model used in this study. Higher doses, however, were able to reduce the oxidative damage. Allopurinol (20 mg/kg body weight) had slight effects on GSH and GSSG. All parameters improved using a dose of 50 mg/kg body weight; a dose of 100 mg/kg body weight only showed additional improvement in GSH and GSSG. There was no further change in the other parameters. Allopurinol and oxypurinol concentrations in aqueous humor and retinal tissue showed a dose dependency reaching scavenger concentrations after application of 50 mg/kg body weight of allopurinol. Conclusions. These results suggest that the xanthine oxidase mechanism plays a minor role in the oxidative tissue damage due to lens-induced uveitis. Free radicals and oxidants are generated by activated leukocytes; therefore, the effect of higher doses of allopurinol is due to its free radical scavenging and antioxidative activity. Invest Ophthalmol Vis Sci. 1994; 35:3897-3904. Allopurinol is widely used in clinical medicine for the treatment of hyperuricemia. A reduction in uric acid is achieved by the inhibition of the enzyme xanthine oxidase. In ischemic diseases, xanthine oxidase uses oxygen as a reduction equivalent, leading to the formation of superoxideanion radicals. Therefore

Comparative evaluation of diode laser versus argon laser photocoagulation in patients with central serous retinopathy: A pilot, randomized controlled trial [ISRCTN84128484]

BACKGROUND: To evaluate the efficacy of diode laser photocoagulation in patients with central serous retinopathy (CSR) and to compare it with the effects of argon green laser. METHODS: Thirty patients with type 1 unilateral CSR were enrolled and evaluated on parameters like best corrected visual acuity (BCVA), direct and indirect ophthalmoscopy, amsler grid for recording scotoma and metamorphopsia, contrast sensitivity using Cambridge low contrast gratings and fluorescein angiography to determine the site of leakage. Patients were randomly assigned into 2 groups according to the statistical random table using sequence generation. In Group 1 (n = 15), diode laser (810 nm) photocoagulation was performed at the site of leakage while in Group 2 (n = 15), eyes were treated with argon green laser (514 nm) using the same laser parameters. Patients were followed up at 4, 8 and 12 weeks after laser. RESULTS: The mean BCVA in group 1 improved from a pre-laser decimal value of 0.29 ± 0.14 to 0.84 ± 0.23 at 4 weeks and 1.06 ± 0.09 at 12 weeks following laser. In group 2, the same improved from 0.32 ± 0.16 to 0.67 ± 0.18 at 4 weeks and 0.98 ± 0.14 at 12 weeks following laser. The improvement in BCVA was significantly better in group 1 (p < 0.0001) at 4 weeks. At 4 weeks following laser, all the patients in group1 were free of scotoma while 6 patients in group 2 had residual scotoma (p < 0.05). The mean contrast sensitivity in group 1 improved from pre-laser value of 98.4 ± 24.77 to 231.33 ± 48.97 at 4 weeks and 306.00 ± 46.57 at 12 weeks following laser. In group 2, the same improved from 130.66 ± 31.95 to 190.66 ± 23.44 at 4 weeks and 215.33 ± 23.25 at 12 weeks. On comparative evaluation, a significantly better (p < 0.001) improvement was noted in group 1. CONCLUSION: Diode laser may be a better alternative to argon green laser whenever laser treatment becomes indicated in patients with central serous retinopathy in terms of faster visual rehabilitation and better contrast sensitivity. In addition, diode laser also has the well-recognized ergonomic and economic advantages

OPERATIVE BEHANDLUNG DER MYOPIE (RADIARE KERATOTOMIE)

Beschreibung der weltweiten Adoption der radiaeren Keratotomie fuer die Behandlung der Myopie

Combined relaxing incisions and epikeratophakia for the correction of aphakia and high postkeratoplasty degree astigmatism

A combined surgical procedure consisting of corneal relaxing incisions and epikeratophakia was used to correct high-degree postkeratoplasty astigmatism and aphakia in two patients. Both patients achieved their final refractive result as soon as 1 month after suture removal (2 and 3 months after surgery, respectively). Keratometric readings showed a reduction of approximately 20.00 diopters in one case and 10.00 D in the other, while the spherical equivalent changed from +10.00 D to +0.50 D in one eye and from +7.50 D to +1.75 D in the other. Spectacle correction was prescribed for both patients. At the last follow-up visit, about 2 years after surgery, these values were unchanged. The main advantage of the combined technique over two separate procedures was that postoperative visual rehabilitation was faster. Equally important was the stability of the refractive result over a long period of time after surgery, as well as the absence of negative effects on the preexisting corneal graft. In spite of the technical complexity of a combined surgical procedure, this approach probably represents the best choice in rare cases such as the ones reported here

Electron microscopic examination of prelathed, lyophilized tissue used for epikeratophakia in humans

Electron microscopic findings obtained in the analysis of prelathed, lyophilized tissue lenses for epikeratophaki

DIE CHRONISCHE LOW-GRADE-ENDOPHTHALMITIS. EINE WACHSENDE INDIKATION ZUR EXPLANTATION VON INTRAOKULARLINSEN

The aim of this study was to evaluate the effect of progress made in cataract surgery regarding the indications and results of intraocular lens (IOL) removal. For this purpose, the charts of all patients who had undergone IOL explantation at our institution between January 1990 and December 1992 were reviewed. Indications were divided into six groups: (a) chronic low-grade endophthalmitis; (b) pseudophakic bullous keratopathy; (c) luxation; (d) traumatic expulsion; (e) high-degree aniseikonia; (f) acute endophthalmitis. Visual acuities were grouped according to a good (1.0 to 0.5) acceptable (0.4 to 0.05) and poor (less than 0.05) outcome. Fifty-two IOL were removed from 52 eyes of 52 patients during the period considered in this study. Sixteen were anterior chamber, 5 were iris-fixated, and 31 were posterior chamber lenses. The removal rates were 30.8% for chronic, low-grade endophthalmitis (n = 16), 28.8% for bullous keratopathy (n = 15), 28.8% for luxation (n = 15), 5.8% for traumatic expulsion (n = 3), 3.8% for high-degree aniseikonia (n = 2), and 1.9% for acute endophthalmitis (n = 1) After explantation vision equal to or better than 20/400 was achieved by the vast majority of patients in all groups with the exception of those with bullous keratopathy. The progress made in cataract surgery over the last decade has greatly influenced the rate of complications leading to IOL removal. Continuous monitoring of explanted IOLs is mandatory to evaluate further changes in surgical technique and lens design