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Biomedical subjects

M S Blumenkranz

Publications and source records attributed to M S Blumenkranz.

At least 19 recordsLinked to original sources
PubMed2007

[The effectiveness of the new fluoroquinolones against the normal bacterial flora of the conjunctiva].

BACKGROUND: Our aim was to determine the antibiotic susceptibility of the preoperative conjunctival bacterial flora against 25 commonly used antibiotics, especially the new fluoroquinolones levofloxacin, gatifloxacin, and moxifloxacin. PATIENTS AND METHODS: The Kirby-Bauer disk-diffusion technique was used to test for the in vitro antibiotic susceptibility of conjunctival bacterial strains isolated from 160 patients (median=74 years, mean=71 years) undergoing cataract surgery at the Department of Ophthalmology, Stanford University, CA, USA. RESULTS: Among the 256 bacteria isolated, 201 (79%) were coagulase-negative staphylococci (CNS), 26 Staphylococcus aureus, 15 Streptococcus group D and 14 gram-negative rods. A total of 100 of these 256 strains (39%) were classified as multiresitant (resistant to>or=five antibiotics). The resistance rate (RR) of commonly used antibiotics for all CNS was: gatifloxacin=moxifloxacin<gentamycin=tobramycin=levofloxacin=neomycin<ciprofloxacin=ofloxacin<erythromycin. The RR for S. aureus and the gram-negative rods was low and insignificant in comparison to the other antibiotics tested. None of the Streptococcus group D were resistant to gatifloxacin, levofloxacin, or moxifloxacin, however, they were highly resistant (RR over 30%) to the other antibiotics. Some 50% of the bacteria were resistant to erythromycin. CONCLUSION: Newer generation fluoroquinolones provide excellent efficacy against coagulase-negative staphylococci and Streptococcus group D despite a high number of multiresitant bacteria.

Aged↗
PubMed2001

Fluorescein angiographic findings in ocular siderosis.

PURPOSE: To report a case of siderosis from a retained intraocular iron foreign body manifesting localized retinal capillary nonperfusion documented by fluorescein angiography. METHODS: Case Report. In a 35-year-old man with decreased vision in the left eye, studies included fundus photography, fluorescein angiography, visual field testing, and electrophysiology. Surgical foreign body extraction and histopathologic examination were performed. RESULTS: Preoperatively, in the left eye, humphrey visual fields and electrophysiology testing revealed marked depression. Fluorescein angiography demonstrated nasal capillary nonperfusion with occlusion of the second- and third-order arterioles extending along a gradient from the foreign body. Microscopic examination of the lens capsule confirmed the diagnosis of siderosis secondary to a retained iron foreign body. CONCLUSION: Extensive capillary nonperfusion may be associated with a retained iron intraocular foreign body, as documented by fluorescein angiography.

Adult↗
PubMed2001

Presumed acquired ocular toxoplasmosis in deer hunters.

PURPOSE: To describe acquired ocular toxoplasmosis in deer hunters. METHODS AND RESULTS: The authors describe five young men presenting with flu-like symptoms followed by visual loss due to a unilateral, focal necrotizing retinitis. All five men gave a history of ingesting undercooked or uncooked venison. All five had elevated toxoplasma serology, and all five improved clinically with an antitoxoplasma regimen. CONCLUSION: In previously healthy young men, flu-like symptoms associated with visual loss and retinitis should prompt questioning about hunting and raw game meat ingestion, especially when toxoplasmosis is suspected.

Adolescent↗
PubMed2001

Pulsed electron avalanche knife (PEAK) for intraocular surgery.

PURPOSE: To develop a better and more economical instrument for precise, tractionless, "cold" cutting during intraocular surgery. The use of highly localized electric fields rather than laser light as the means of tissue dissection was investigated. METHODS: A high electric field at the tip of a fine wire can, like lasers, initiate plasma formation. Micrometer-length plasma streamers are generated when an insulated 25 micron (microm) wire, exposed to physiological medium at one end, is subjected to nanosecond electrical pulses between 1 and 8 kV in magnitude. The explosive evaporation of water in the vicinity of these streamers cuts soft tissue without heat deposition into surrounding material (cold cutting). Streamers of plasma and the dynamics of water evaporation were imaged using an inverted microscope and fast flash photography. Cutting effectiveness was evaluated on both polyacrylamide gels, on different tissues from excised bovine eyes, and in vivo on rabbit retina. Standard histology techniques were used to examine the tissue. RESULTS: Electric pulses with energies between 150 and 670 microJ produced plasma streamers in saline between 10 and 200 microm in length. Application of electric discharges to dense (10%) polyacrylamide gels resulted in fracturing of the gel without ejection of bulk material. In both dense and softer (6%) gels, layer by layer shaving was possible with pulse energy rather than number of pulses as the determinant of ultimate cutting depth. The instrument made precise partial or full-thickness cuts of retina, iris, lens, and lens capsule without any evidence of thermal damage. Because different tissues require distinct energies for dissection, tissue-selective cutting on complex structures can be performed if the appropriate pulse energies are used; for example, retina can be dissected without damage to the major retinal vessels. CONCLUSIONS: This instrument, called the Pulsed Electron Avalanche Knife (PEAK), can quickly and precisely cut intraocular tissues without traction. The small delivery probe and modest cost make it promising for many ophthalmic applications, including retinal, cataract, and glaucoma surgery. In addition, the instrument may be useful in nonophthalmic procedures such as intravascular surgery and neurosurgery.

Animals↗
PubMed2000

Lutetium texaphyrin (Lu-Tex): a potential new agent for ocular fundus angiography and photodynamic therapy.

PURPOSE: To investigate the suitability of lutetium texaphyrin (lu-tex) as a fluorescence imaging agent in the delineation of retinal vascular and choroidal vascular diseases. The utilization of an efficient fluorescent molecule that is also a photosensitizer represents a unique opportunity to couple diagnosis and therapy. METHODS: Fundus fluorescence angiography comparing lu-tex (motexafin lutetium, Optrin, Pharmacyclics Inc, Sunnyvale, California) with the conventional angiographic dyes, sodium fluorescein, and indocynanine green (ICG), was performed on the eyes of normal and laser-injured New Zealand white rabbits. Plasma pharmacokinetic data and plasma protein binding were assessed in addition to light microscopy of the retina in both imaged and laser-injured eyes. RESULTS: Normal retinal and choroidal vasculature was well delineated by lu-tex angiography. Experimentally induced choroidal and retinal vascular lesions were enhanced by lu-tex and demonstrated different staining patterns than fluorescein or ICG, particularly at the margins of the lesions. Lu-tex cleared rapidly from the plasma, with 39.7% bound to the high-density lipoprotein (HDL) fraction while 15.8% was bound to the low-density lipoprotein (LDL) fraction. No evidence of retinal toxicity after dye administration was observed by either ophthalmoscopy and fundus photography or by light microscopy. CONCLUSION: Lu-tex angiography is a potentially valuable method for retinal vascular and choroidal vascular evaluation, and it has advantages over fluorescein and ICG angiography. The same agent could conceivably be used for both the identification of abnormal vasculature and subsequent photodynamic treatment.

Animals↗
PubMed1999

The role of digital fundus photography in diabetic retinopathy screening. Digital Diabetic Screening Group (DDSG).

PURPOSE: The role of digital monochromatic nonmydriatic fundus photography as an adjunct in the diagnosis of diabetic retinopathy is evaluated. METHODS: 197 patients were sequentially evaluated by three different techniques: dilated ophthalmoscopy by an experienced ophthalmologist, performance of 7 standard color mydriatic stereo fields, and a single digital monochromatic nonmydriatic image incorporating the disc and macula. Stereo color photographs served as the reference standard and were compared to either ophthalmoscopy performed by a physician, or a single digital photograph transmitted electronically to a reading site and evaluated by a trained non-physician grader. Sensitivity and specificity of the three methods were compared. The decision as to whether or not to refer to an ophthalmologist for potential treatment (Kaiser modified ETDRS level > 21) was then chosen for analysis. RESULTS: A single nonmydriatic monochromatic digital photograph appeared equivalent to standard color photography and more sensitive than mydriatic ophthalmoscopy in the detection of diabetic retinopathy in this patient population. Sensitivity of digital photography compared with color photography was 78%, and the specificity 86% contrasted with comparable ratios of 34% and 100% for ophthalmoscopy versus color photography. No patient identified by ophthalmoscopy alone for referral based on retinopathy level of > 21 would have been missed by a single digital monochromatic photographic image. CONCLUSION: A single nonmydriatic monochromatic wide field digital photograph of the disc and macula in diabetic patients is a sensitive and cost-effective means for detecting diabetic retinopathy in high-risk populations.

Allied Health Personnel↗
PubMed1998

Management of submacular hemorrhage associated with retinal arterial macroaneurysms.

PURPOSE: Experience is reported with intraoperative pharmacologic lysis of recent submacular hemorrhage with tissue plasminogen activator followed by surgical drainage of the unclotted blood in patients with retinal arterial macroaneurysms. METHODS: Nine eyes (nine patients) with a recent (< or = 7 days old) submacular hemorrhage involving the center of the fovea secondary to retinal arterial macroaneurysm that were managed with recombinant tissue plasminogen activator-assisted subretinal hemorrhage evacuation, including subretinal injection of tissue plasminogen activator and removal of the liquefied blood. Patients were followed for a mean 18 +/- 7 months (range, 7 to 30 months). RESULTS: All nine eyes had improved final corrected visual acuity after surgery, and eight eyes (89%) attained a corrected visual acuity of 20/60 or better (mean, 20/40; range, 20/20 to 20/200). Final corrected visual acuity was limited to 20/200 in one eye. Two eyes developed a cataract that required surgery. CONCLUSIONS: Submacular surgery with tissue plasminogen activator-assisted thrombolysis achieved improved best-corrected visual acuity in eyes with recent submacular hemorrhage involving the center of the fovea associated with retinal arterial macroaneurysm.

Aged↗
PubMed1998

Treatment of reopened macular hole after vitrectomy by laser and outpatient fluid-gas exchange.

OBJECTIVE: This study aimed to assess a new nonsurgical treatment for patients who have previously undergone vitrectomy for macular hole with either persistent or reopened holes. DESIGN: A prospective, noncomparative, consecutive case series. PARTICIPANTS: Fifteen patients (15 eyes) were studied. INTERVENTION: Patients were treated by an outpatient method consisting of laser photocoagulation to the foveal pigment epithelium followed by fluid-gas exchange with 20% perfluoropropane gas and prone positioning. Patients without known allergy were treated with two doses of oral Diamox (250 mg) and ciprofloxacin (500 mg). MAIN OUTCOME MEASURES: Visual acuity, intraocular pressure, anatomic status of the macular hole, and cataract were the principal outcome measures studied. RESULTS: Thirteen of 15 macular holes were closed successfully with 1 or more procedures. All patients with macular hole closure achieved two lines or greater of vision improvement on Snellen testing. Three patients (20%) achieved 20/40 and nine (60%) achieved 20/80 or better. Three patients required more than one procedure. Four patients developed mild transient ocular hypertension. CONCLUSIONS: The combination of office-based outpatient fluid-gas exchange and laser appears to be a safe and cost-effective alternative to repeat surgery in selected patients with persistent or reopened macular holes after vitrectomy, in whom there are no visible epiretinal membranes, or in whom return to the operating room is undesirable for medical or personal reasons.

Aged↗
PubMed1998

Exudative retinal detachment in X-linked retinoschisis.

X-linked retinoschisis is a vitreoretinal dystrophy characterized by foveal and peripheral retinoschisis in the nerve fiber layer. Although many associated peripheral retinal findings have been reported, few reports have described massive exudative retinal detachments in patients with X-linked retinoschisis. The authors report the unusual occurrence of Coats'-like exudative retinopathy in two patients with X-linked retinoschisis. Both patients had peripheral massive exudative retinal detachments.

Adult↗
PubMed1997

Subretinal hemorrhages in proliferative diabetic retinopathy.

PURPOSE: To describe the clinical features of patients with advanced proliferative diabetic retinopathy who underwent vitrectomy and were found to have subretinal hemorrhages. METHODS: The authors conducted a retrospective study of 49 patients with complications of proliferative diabetic retinopathy requiring pars plana vitrectomy and demonstrating the presence of subretinal hemorrhage. Preoperative, intraoperative, and postoperative clinical characteristics were evaluated. Patients were observed for a minimum of 6 months. RESULTS: The location, size, and clearance of subretinal hemorrhages revealed wide variation. Forty-two patients had focal subretinal hemorrhages, and 14 patients within this group had submacular hemorrhages. A retinal break was observed in 15 patients (31%). Only one patient required drainage of the subretinal hemorrhage to achieve retinal reattachment. Vitreous surgery resulted in 59% of patients achieving a visual acuity > or = 5/200. Seventy-nine percent had stable or improved vision, whereas 20% had worse vision after surgery. CONCLUSION: Subretinal hemorrhages appear to be an uncommon feature associated with long-term, advanced proliferative diabetic retinopathy and portend a guarded visual prognosis. These hemorrhages may occur spontaneously in previously untreated eyes and are often unsuspected until observed at the time of vitreous surgery. In general, removal of subretinal hemorrhages was not necessary to achieve macular anatomic attachment, and most patients experienced improved visual function after surgery. Diabetic subretinal hemorrhages may indicate a retinal break, and, therefore, careful ophthalmic inspection should be performed in these patients.

Adolescent↗
PubMed1996

Multicenter clinical experience using an erbium:YAG laser for vitreoretinal surgery.

PURPOSE: To evaluate the advantages, disadvantages, safety, complications, and surgical applicability of an erbium:YAG laser system for maneuvers in vitreoretinal surgery. METHODS: A prospective, consecutive trial of 68 eyes in 66 patients undergoing vitreoretinal surgery in which an erbium:YAG laser with graduated output from 0.2 to 5.0 mJ per pulse, repetition rate of 2 to 30 Hz, and equipped with a flexible fiber optic and interchangeable 20-gauge intraocular fiber optic endoprobes was used to perform specific maneuvers, including transection, incision, and ablation of membranes, retinotomy, vessel coagulation, iridectomy, and lens tissue ablation. The patients were treated in five centers in contemporary vitreoretinal surgical settings for surgical indications, including proliferative diabetic retinopathy, proliferative vitreoretinopathy, epiretinal membrane, and retinopathy of prematurity. RESULTS: One hundred seventy-four maneuvers were performed with an overall surgical efficacy rating of excellent or good in 84% of maneuvers, ranging from a high of 100% for subretinal membrane transection to a low of 25% for coagulation of blood vessels. Complications included retinal break or photocoagulative injury in 5% of epiretinal membrane incisions, minor bleeding from transected retinal vessels during 29% of retinotomies, and intraocular lens damage during two posterior capsulotomies. The most significant limitation was the cautious pace used during maneuvers near the retinal surface. CONCLUSION: The erbium:YAG laser is capable of versatile new approaches offering precise tissue cutting and ablation in vitreoretinal surgical maneuvers with a high degree of safety. The main limitation encountered was the slow speed of certain critical maneuvers near the retina.

Adult↗
PubMed1995

Improved surgical treatment of familial exudative vitreoretinopathy in children.

PURPOSE: To evaluate current surgical results in patients with familial exudative vitreoretinopathy and study the histologic findings of epiretinal membranes obtained at the time of surgery. METHODS: We performed phakic pars plana vitrectomy and membrane peeling on five patients (six eyes) with familial exudative vitreoretinopathy, who ranged in age from 18 months to 9 years and had traction retinal detachment. Membranes from two eyes (two patients) were analyzed by light and electron microscopy. RESULTS: The macula was reattached in all six eyes. Visual acuity improved after surgery in five of the six eyes, with two eyes improving from a preoperative visual acuity of 20/400 to a postoperative visual acuity of 20/25 and 20/60. Electron microscopic analysis of the membranes from two patients disclosed thick fibrocellular fragments with vascular elements and astrocytes. CONCLUSION: With current surgical techniques, there appears to be improvement in the anatomic reattachment rate and visual outcome in patients with familial exudative vitreoretinopathy. Amblyopia, reproliferation, and vitreous hemorrhage may limit long-term improvement in vision.

Basement Membrane↗
PubMed1995

Cotton-wool spots and the early diagnosis of giant cell arteritis.

BACKGROUND: Giant cell arteritis is a common cause of severe visual loss in older individuals. Patients often present to the ophthalmologist having already lost vision in one eye. Detection of early ophthalmoscopic signs that precede irreversible visual loss in giant cell arteritis would allow preventative treatment in an otherwise frequently blinding disease. METHODS: Case presentations. RESULTS: Seven patients with mild visual symptoms and results of an ophthalmologic examination significant for cotton-wool spots were found to have giant cell arteritis. On specific questioning, six of seven patients described constitutional symptoms consistent with giant cell arteritis. Six patients had an abnormally elevated Westergren erythrocyte sedimentation rate. Temporal artery biopsy confirmed giant cell arteritis in six patients. The seventh patient received a diagnosis of polymyalgia rheumatica. Prompt treatment with corticosteroids led to preservation of vision and uneventful resolution of the cotton-wool spots in all seven patients. CONCLUSION: Cotton-wool spots are an early ophthalmoscopic finding in giant cell arteritis and can precede severe visual loss. Recognition of the significance of cotton-wool spots, use of laboratory studies, and prompt treatment may preserve vision in an otherwise frequently blinding disease.

Aged↗