Halit Oguz

The role of oxidative stress in diabetic retinopathy

Purpose To investigate the role of oxidative stress in the development of diabetic retinopathy.Methods This study included 25 patients with diabetic retinopathy (group 1), 34 patients with non-insulin-dependent diabetes mellitus without any angiopathy complications (group II) and 26 healthy subjects (group III). The serum malondialdehyde (MDA)-like metabolite levels as an index of lipid peroxidation, the erythrocyte glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and serum vitamin C levels of the patients and healthy subjects were measured.Results The mean serum concentration of MDA-like metabolites of patients in group I was 4.38 ± 1.31 nmol/ml, in group II was 3.38 ± 0.95 nmol/ml and in group III was 2.61 ± 0.85 nmol/ml. There were significant differences between the groups (p = 0.001 for group I compared with group II, p = 0.0001 for group I compared with group III and p = 0.002 for group II compared with group III). There was a significant correlation between the serum lipid peroxidation concentrations and duration of the disease (r = 0.36, p = 0.047). The mean erythrocyte GSH-Px and SOD levels of group I were respectively 68.97 ± 18.04 and 1597.78 ± 296.46 U/g Hb, of group II were 64.30 ±19.26 and 1581.33 ± 278.08 U/g Hb, and of group III were 65.52 ± 17.58 and 1587.44 ± 281.17 U/g Hb. There were no significant differences among the antioxidant enzyme levels in the three groups (p > 0.05). The mean serum vitamin C level in group I was 42.72 ± 8.90 μmol/l, in group II was 49.26 ± 11.52 μmol/l and in group III was 58.57 ± 9.75 μmol/l. There were significant differences among the mean serum vitamin C levels of the three groups (p = 0.02 for group I versus group II p = 0.001 for group I versus group III and p = 0.002 for group II versus group III).Conclusions Free radicals forming in diabetes mellitus and increasing over time may play a role in the development of diabetic retinopathy, which is an important complication of the disease.

The Use of Hyperbaric Oxygen Therapy in Ophthalmology

Hyperbaric oxygen therapy is a primary or adjuvant therapeutic method used in treatment of various acute or chronic disorders. Currently, eye diseases are among the off-label use of hyperbaric oxygen. However, there is an increasing body of evidence showing its safety and efficacy in retinal artery occlusion, cystoid macular edema secondary to retinal vein occlusion, scleral thinning and necrosis faced after pterygium surgery, orbital rhino-cerebral mucormycosis, nonhealing corneal edema, and anterior segment ischemia. Its potential to treat some blinding disease has also been pointed out in recent studies. This article constitutes an up-to-date summary of knowledge and therapeutic use of hyperbaric oxygen, and aims to contribute understanding of current and potential use of hyperbaric oxygen therapy in ophthalmology.

Treatment of Xanthelasma Palpebrarum with Argon Laser Photocoagulation

Purpose: We report the results of argon laser coagulation of xanthelasma lesions. Methods: Forty eyelids of 24 patients with xanthelasma were treated in 1 to 4 sessions at 2–3 week intervals, using an argon green laser. The laser parameters were as follows: wavelength 514 nm; spot size 500 microns; energy 900 mW; the duration of the laser pulse 0.1–0.2 seconds. The procedure was done on outpatient basis. A gauze pad soaked in topical anaesthetic eye drops was applied to the surface of the lesion. Results: The therapy was well tolerated, and all lesions responded to the therapy. There were no complications and no functionally relevant scar developed. The cosmetic outcome was considered to be good in 85% of the cases. Conclusion: Argon laser photocoagulation represents an alternative treatment in selected cases. It is easy to perform and well tolerated by the patients.

The antibacterial effect of topical anesthetic proparacaine on conjunctival flora

Purpose: To investigate the antibacterial effect of topical anesthetic proparacaine on conjunctival flora.Methods: One hundred and forty-four eyes of 72 patientsawaiting cataract surgery were included in the study. A commercially available solution of proparacaine, preserved with benzalkonium chloride 0.01%, was instilled in one eye of all subjects while the vehicle solution, including the same concentration of preservative in aqueous solution, was administered to the other eye. Conjunctival cultures were taken from all eyes before and 15 minutes after the instillation of proparacaine and the vehicle.Results: Of the 144 eyes, 76 (52.8%) had positive-conjunctival cultures with the most commonly isolated organisms being coagulase-negative staphylococci in each group. Of the 76 culture-positive eyes, 40 (52.6%) received proparacaine and 36 (47.4%) the vehicle preparation. Fifteen minutes after the instillation of proparacaine and the vehicle eyedrops, four eyes (10%) and 12 eyes (33.3%) had culture-positive conjunctival smears, respectively. Proparacaine significantly reduced the number of culture-positive eyes (p = 0.0003), in contrast to the vehicle (p = 0.21).Conclusion: A topicalanesthetic, proparacaine, demonstrates antibacterial effects on the conjunctival flora.

Ophthalmic techniques described by Serefeddin Sabuncuoğlu (1385-1468 AD).

¸Serefeddin Sabuncuoglu (1385−1468 ad) was a Turkish surgeon who lived in the Ottoman Empire during the fifteenth century, a time of progressive expansion. When in his eighties, he wrote Cerrahiyyetü’l‐Haniyye, which means Imperial Surgery. His book is the first example of an illustrated surgical textbook in the Turkish−Islamic medical literature. The importance of his book rests upon the inclusion of colour miniatures of the surgical procedures, incisional techniques and instruments, all drawn by Sabuncuog˘lu himself. Only three hand‐written copies exist, two of which were originally written by the author and are currently exhibited in Paris and Istanbul. The book was rediscovered in 1936, but some parts of it are still suspected to be missing. At present, the book consists of three chapters divided into 193 known sections. The sections deal with all fields of surgery including ophthalmology, and cite relevant Greek, Arabic and Persian textbooks. In this historical article the sections of Cerrahiyyetü’l‐Haniyye pertinent to ophthalmology are critically reviewed, including a selection of the coloured drawings.

Diabetic Retinopathy in Pregnancy: Effects on the Natural Course

Pregnancy can cause changes in the functioning of the eye in health and in disease and also affect preexisting ocular conditions, such as diabetic retinopathy. Progression of retinopathy in pregnancy depends on a variety of factors, including severity of retinopathy at conception, adequacy of treatment, duration of diabetes, metabolic control before pregnancy, and the presence of additional vascular damage (ie, preexisting or concomitant hypertensive disorder). Developments in medical, obstetrical, and ophthalmologic management of the pregnant diabetic have greatly improved the prognosis for successful pregnancies and maintaining vision.

Microbiologic Analysis of Aqueous Humor in Phacoemulsification

PURPOSE This study was designed as a microbiologic survey of the fluids aspirated from the anterior chamber at the end of cataract extraction performed by phacoemulsification, and to correlate the contamination rate of the anterior chamber to the surgical technique used. METHODS One hundred and one consecutive patients (126 eyes) who underwent cataract extraction by phacoemulsification and posterior chamber intraocular lens implantation were included in the study. Microscopical examination, culture, and determination of the number of colonies were carried out on the bacteria and fungi in the anterior chamber fluids aspirated at the end of surgery, before final suture placement. RESULTS Anterior chamber fluids yielded positive cultures in nine specimens (8.14%), six of which were identified as coagulase-negative staphylococci. Quantification disclosed colony counts ranging between 2-10 and 10-40 per mL. CONCLUSIONS Preliminary results in a small population show that the contamination of the aqueous humor is significantly less frequent if the cataract extraction is performed by phacoemulsification.

Effectiveness of Topical Taurolidine versus Ciprofloxacin, Ofloxacin, and Fortified Cefazolin in a Rabbit Staphylococcus aureus Keratitis Model

Purpose. Taurolidine is a broad-spectrum, nonantibiotic antimicrobial agent, not previously tested against the common causes of bacterial keratitis. This study, employing an experimental rabbit model of Staphylococcus aureus keratitis, investigated the effectiveness of topical taurolidine in reducing the number of bacteria, and its effectiveness was compared with topical ciprofloxacin, ofloxacin, and 5% cefazolin.Methods. The right corneas of all rabbits were intrastromally injected with 100 colony-forming units of Staphylococcus aureus ATCC strain 25923. The animals were divided into the following seven groups: Group 1 (6 rabbits) received taurolidine, group 2 (6 rabbits) received ciprofloxacin, group 3 (6 rabbits) received ofloxacin, group 4 (6 rabbits) received cefazolin, group 5 (5 rabbits) received polyvinylpyrrolidone (vehicle), group 6 (4 rabbits) received sterile water, and group 7 (4 rabbits) was left untreated (control group). The eyes were topically treated every 30 min with the above-mentioned substances from 4 to 9 h postinjection. One hour after the last drop administration (at 10 h postinjection), signs of inflammation were scored in a masked fashion by slit-lamp examination. Then, their corneas were processed. The number of colony-forming units (cfu) per cornea in all eyes was also determined.Results. All antimicrobial (taurolidine, ciprofloxacin, ofloxacin, and cefazolin) treatments significantly reduced cfu numbers and slit-lamp examination scores compared with untreated eyes, eyes that received the vehicle, or eyes with sterile water (all p values < 0.05). Regarding cfu numbers, although taurolidine therapy was significantly less effective than ciprofloxacin or ofloxacin, there was no significant difference between taurolidine and cefazolin groups. However, taurolidine had similar clinical examination scores with the other antimicrobials, while it had lower scores than the vehicle, sterile water, or untreated eyes. Conclusions. The results obtained in this study suggest that topical taurolidine is an effective, novel ocular chemotherapeutic agent for the therapy of rabbit experimental Staphylococcus aureus keratitis. This drug may be a useful and promising ocular antimicrobial.

Intravitreal taurolidine against experimental Staphylococcus epidermidis endophthalmitis in rabbits

Purpose. Taurolidine is a broad spectrum, non-antibiotic antimicrobial agent, not previously tested against infectious endophthalmitis. The efficacy of intravitreal taurolidine in the treatment of experimental Staphylococcus epidermidis endophthalmitis was evaluated and compared with vancomycin in a rabbit model. Methods. The right eyes of 34 albino rabbits were infected with an intravitreal inoculum of S. epidermidis (10 5 colony-forming units/0.1 ml). The right eyes of four rabbits (group 7) were not infected and served as uninfected controls. 24 hours after inoculation of bacteria the animals were divided into the following treatment groups: group 1 (7 rabbits) received intravitreal taurolidine at 24 hours and group 2 (7 rabbits) received at 48 hours. Group 3 (7 rabbits) received vancomycin at 24 hours and group 4 (7 rabbits) at 48 hours. Group 5 (3 rabbits) received polyvinylpyrrolidone at 24 hours and group 6 (3 rabbits) at 48 hours. Clinical scoring was performed at 24, 48 and 72 hours. At 72 hours post inoculation, vitreous samples were collected for quantitative microbiological studies and then, the eyes were enucleated for histopathological scorings. Results. The clinical and histopathological examinations revealed significant amelioration of inflammation in eyes treated with taurolidine and vancomycin when compared with polyvinylpyrrolidone. The eyes treated with taurolidine also had significantly lower colony forming units than the eyes treated with polyvinylpyrrolidone and taurolidine rendered many eyes sterile. Conclusion. Taurolidine is expected to be a potential agent for treatment of S. epidermidis endophthalmitis.

No effects of long-term sildenafil treatment on ocular functions

PurposeSildenafil is a new and effective oral medication for the treatment of erectile dysfunction. The purpose of this study was to assess the long-term effects of sildenafil on visual acuity, color vision, intraocular pressure (IOP), electroretinography (ERG), blue-on-yellow and white-on-white Humphrey visual field (HVF), and tear functions.MethodsTen impotent patients ingested 50 mg of sildenafil one or more times a week for a minimum of 3 months. Ten age-matched subjects without any ophthalmological disorders other than refractive problems served as controls. Visual acuity (Snellen), color discrimination (Ishihara), and a slit-lamp examination were performed on the patients. Cotton thread and Schirmer I tests and tear break-up time were applied to random eyes of all subjects. IOP was measured in both eyes of the patients by Goldmann applanation tonometry. Both eyes of each subject were tested with white-on-white (fastpac 30-2, size 3 stimulus) followed by blue-on-yellow (fastpac 30-2, size 5 stimulus) HVF analyzer. ERG in scotopic (dark-adapted) condition was performed with unipolar corneal electrodes and rod response was recorded.ResultsIn comparison with control, no clinically or statistically significant differences were detected in the patients ingesting sildenafil with regard to the visual acuity, color discrimination, IOP, mean deviation, cotton thread and Schirmer I tests, tear break-up time, amplitude, and implicit time of b-wave.ConclusionLong-term treatment with sildenafil did not produce any significant abnormality on ocular functions. Repeated exposures of ocular tissues to therapeutic doses of sildenafil are unlikely to impair their functions.