Biomedical subjects
Publications and source records attributed to T R Friberg.
Previous studies have found increased pancreatic intraductal pressures in dogs and the development of acute pancreatitis in humans after cholinergic stimulation. However, we did not find abnormally high levels of serum lipase or serum amylase in 44 patients with glaucoma using therapeutic doses of echothiophate iodide for intraocular pressure control on a long-term basis.
Aphakic cystoid macular edema was demonstrated angiographically in both eyes of the patient, two months after bilateral cataract extraction. The right eye, which suffered a previous temporal branch artery occlusion, demonstrated a distinctive semicircular pattern of edema. No leakage of fluorescein occurred in the region below the horizontal raphe. The case illustrates that aphakic cystoid macular edema is caused by abnormalities in the retinal, rather than the choroidal, vasculature.
A patient with decreased visual acuity had small, glistening white particles that were scattered over both posterior poles. Monochromatic fundus photography revealed ghost vessels and intraluminal particulate matter in small retinal vessels. Fluorescein angiography demonstrated nonperfusion of small arterioles and macular capillaries. The patient admitted to multiple intravenous injections of crushed methylphenidate (Ritalin) hydrochloride tablets, which contain talc 18 months prior to examination. To our knowledge, visual loss and irreversible macular ischemia from talc emboli have not been previously documented.
Schlieren or streaks can be observed as light passes through incompletely mixed fluids having different refractive indices. During vitreous surgery, the vitreous humor is replaced by an aqueous solution whose density and refractive index differ from those of subretinal fluid. The observation of schlieren during vitrectomy therefore suggests the presence of subretinal fluid and a retinal hole. After observing this sign, a careful search should be made for the retinal break if it has not been previously diagnosed.
A 17-year-old girl was struct in the right eye by a mortarboard tossed into the air during high school graduation exercises. She suffered commotio retinae with damage to the retinal pigment epithelium and macular hole formation. Fluorescein angiography in the acute stages revealed diffuse staining at the level of the pigment epithelium. Five months later, the areas of abnormal staining had undergone depigmentation and dye no longer accumulated in the pigment epithelial layer. The fluorescein findings in traumatic retinal pigment epithelial edema are unusual.
Visual loss is uncommon in thrombosis of the cavernous sinus. A patient observed closely in the acute stages developed high introcular and intraorbital pressures. Although the retinal vasculature remained patent, total unilateral blindness occurred within 48 hours. To our knowledge this is the first documented case in which ischemic optic neuropathy caused blindness in a patient suffering from cavernous sinus thrombosis.
Clinical, ophthalmoscopic, perimetric, and color vision tests and visual evoked responses were recorded in symptomatic and asymptomatic eyes in five members of a family with Leber hereditary optic atrophy. The presymptomatic eyes showed abnormalities in the retinal nerve fiber layer. Optic nerve dysfunction was found before central vision failed. The appearance of degenerating retinal nerve fibers, particularly in the papillomacular bundle, was documented photographically in the weeks after the onset of visual symptoms. Treatment with prednisone and hydroxocobalamin did not reverse or halt serious impairment of vision.
PURPOSE: To define one possible etiology for the rise in intraocular pressure (IOP) after neodymium: YAG (Nd:YAG) laser capsulotomy and provide information for the continued investigation of this process. SETTING: Laser Center, Eye and Ear Institute, Pittsburgh, Pennsylvania. METHODS: Samples of 1% sodium hyaluronate or balanced salt solution (BSS) (control) were placed in a closed system and exposed to varying amounts of Nd:YAG energy delivered by a Coherent YAG laser. This system was hydrostatically coupled to a pressure monitor, and changes in pressure were recorded as a function of time. RESULTS: Average pressure increase was 0.140 mm Hg/mJ of YAG energy in the sodium hyaluronate samples and 0.017 mm Hg/mJ in BSS (P < .01). The relationship between total energy delivered and maximum pressure recorded for both substances was nearly linear. Further analysis of treated sodium hyaluronate samples showed that Nd:YAG energy can produce structural alterations. CONCLUSIONS: Neodymium:YAG laser energy has a pronounced effect on sodium hyaluronate that exceeds the thermal effect seen with BSS when the pressure is monitored in a closed system. These structural changes might contribute to the IOP rise seen clinically.
PURPOSE: Ocular trauma is one of the main causes of visual reduction or loss, particularly in the younger population. METHODS: In this prospective study the authors included 67 consecutive patients with ocular trauma secondary to motor vehicle accidents who were hospitalized in the Athens University Eye Clinic from September 1993 to December 1996. The mean follow-up time was 31 months, the mean age was 31.7 years, and the ratio between men and women was 2.7:1. RESULTS: Thirty-two of the accidents (47.76%) took place in populated areas. Among the 67 injured persons, 58 (86.56%) were car passengers, 8 (11.95%) were on motorcycles, and 1 (1.49%) was a pedestrian. Only 3 (5.2%) of the 58 persons injured inside automobiles used safety belts and none of the motorcyclists used crash helmets during the accidents. Fifty-three (79.1%) ocular traumas were penetrating in nature, with glass fragments being the main cause in 36 of them (67.9%). Among the 53 injured persons experiencing penetrating ocular trauma, 49 had a follow-up time of more than 6 months. Twenty of them (40.8%) underwent one surgical procedure, 22 (44.9%) were submitted to two surgical procedures, and the remaining 7 persons (14.3%) needed three or more operations. Eighteen (36.7%) of the 49 patients with penetrating ocular trauma and with 6 months follow-up had a final visual acuity of less than 1/20, 21 (42.9%) had a visual acuity of more than 5/10, and 3 (6.1%) underwent enucleation. Among the 67 patients, 61 had a follow-up time of more than 6 months, regardless of their history of penetrating ocular trauma. Eighteen of them (29.5%) had a final visual acuity of less than 1/20, 8 (13.1%) had a visual acuity between 2/10 and 4/10, and 22 (52.5%) had a visual acuity of more than 5/10. CONCLUSIONS: Because motor vehicle accidents can cause severe ocular trauma, it would be helpful for drivers to be more careful and aware of motor vehicle regulations. There seems to be a great need of enforcement of seatbelt laws in Greece.
Subretinal neovascular membranes (SRNVM) in the pediatric population are rare. The clinical presentation, etiology, course, and management of SRNVM in 25 children (27 eyes) were studied retrospectively. Inflammatory or infectious conditions predominated (10 of 25). Eleven of 19 untreated SRNVM (58%) spontaneously involuted, with 9 of these 11 achieving a final visual acuity of 20/50 or better. A hyperpigmented ring on fluorescein angiography was associated with 9 of the 11 involuted SRNVM. The presence of this pigmented ring may help to identify those cases with a better visual prognosis.
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BACKGROUND AND OBJECTIVE: Some patients with macular disease, because of physical infirmity or disability, cannot be treated with laser photocoagulation using a typical slit lamp delivery system. The purpose of this study was to determine whether the binocular indirect ophthalmoscope could be used to deliver treatment to the macula when photocoagulation would otherwise be very difficult, if not impossible, to perform. MATERIALS AND METHODS: Ten eyes of 10 patients who could not sit for slit lamp laser delivery were treated with binocular indirect ophthalmoscope laser photocoagulation over a 36 month period. Eight had subfoveal choroidal neovascularization (CNV) from age-related macular degeneration (AMD), and 2 patients had clinically significant macular edema (CSME) from diabetes mellitus. Argon laser photocoagulation was delivered to the choroidal neovascular membrane in patients with exudative AMD, and a grid treatment was given to eyes with diabetic macular edema. RESULTS: Six of 8 patients with exudative AMD were successfully treated with eradication of the CNV. Two required retreatment within 6 months of original treatment. Both patients with CSME had resolution of their edema at 3 and 6 months after treatment. Best corrected visual acuity did not change by more than 2 Snellen lines in any patient with CNV and 1 Snellen line in patients with CSME. No complications of treatment were encountered. CONCLUSION: In certain circumstances, laser photocoagulation of the macula using the indirect ophthalmoscope laser delivery system should be considered when more conventional treatment strategies cannot be implemented.
BACKGROUND AND OBJECTIVE: Corneal decompensation and complications are a frequent cause of visual loss after vitreoretinal surgery. This paper presents data regarding endothelial cell loss in aphakic and pseudophakic silicone oil filled eyes when oil was retained for many months. This study updates our previous investigation on the subject. PATIENTS AND METHODS: The corneal endothelial cell count of 10 eyes of 10 consecutive patients who had undergone vitreoretinal surgery, including fluid-gas exchange and ultimately silicone oil placement, were obtained. The patients underwent an average of 2.7+/-0.9 vitreoretinal procedures before the final procedure which induced the placement of silicone oil in the vitreous cavity. All had inferior iridectomies. The endothelial cell density measurements were obtained an average of 1 year after silicone oil placement. In all eyes, the oil was felt necessary for long term tamponade and therefore was not removed. The cell density of the operated eye was compared to the fellow eye, none of which had undergone silicone oil placement. RESULTS: Both gas and retained silicone oil contribute to the loss of corneal endothelial cell density. The average endothelial cell loss in the 10 eyes with oil retained for an average of 10+/-12 months was 68.8 +/-31.4%, as compared to the fellow eye. The average cell loss was higher in the three eyes with silicone oil in the anterior chamber (range 44 to >95%). Pseudophakic eyes fared better, on average, than aphakic eyes (51.66+/-28% vs. 66.63+/-26.3%) with respect to cell loss. Five aphakic eyes and 1 pseudophakic eye developed corneal edema. CONCLUSIONS: Endothelial cell loss occurs after vitreoretinal surgery and is exacerbated by long term silicone oil retention. The corneal endothelial cell damage is probably cumulative from procedure to procedure. Endothelial cell loss may be pronounced in eyes without a physical barrier between the anterior segment and the vitreous cavity, and in eyes where oil migrates into anterior chamber.
BACKGROUND: Although pneumatic retinopexy was introduced for the repair of primary retinal detachments, we have had excellent long-term success in employing this technique along with laser photocoagulation following failure of routine scleral buckle surgery in nonvitrectomized eyes over the last 10 years. PATIENTS AND METHODS: We categorized a consecutive series of 40 eyes that failed primary scleral buckling surgery and had at least six months follow-up. Eyes were separated into two groups: those with 1) subretinal fluid persisting or developing during the first 14 days after surgery or 2) those accumulating subretinal fluid at least 14 days after initially successful anatomic reattachment of the retina. RESULTS: In these groups, 36 of the 40 eyes (90%) were successfully reattached using outpatient pneumatic retinopexy alone. Complications were limited to the production of new retinal breaks in 5 patients. The 4 pneumatic retinopexy failures were all subsequently treated successfully with either scleral buckle revision or vitrectomy. CONCLUSION: We believe that laser pneumatic retinopexy repair of recurrent retinal detachments following scleral buckle and without significant proliferation vitreoretinopathy (PVR) should be considered ahead of conventional surgical intraoperative techniques. Laser pneumatic retinopexy may be a very successful procedure for the treatment of recurrent retinal detachments after failed scleral buckle surgery. In a consecutive series of 40 eyes with recurrent retinal detachment, we were able to repair 36 with pneumatic retinopexy alone.
To determine the ocular manifestations of inverting the human body into a head-down vertical position, we evaluated normal volunteers with applanation tonometry, fundus photography, fluorescein angiography, and ophthalmodynamometry. Compared with data obtained in the sitting position, the intraocular pressure more than doubled on inversion (35.6 +/- 4 v 14.1 +/- 2.8 mm Hg, n = 16), increasing to levels well within the glaucomatous range. Pressures in the central retinal artery underwent similar increases, while the caliber of the retinal arterioles decreased substantially. External ocular findings associated with gravity inversion included orbital congestion, conjunctival hyperemia, petechiae of the eyelids, excessive tearing (epiphora), and subconjunctival hemorrhage. We suggest that patients with retinal vascular abnormalities, macular degeneration, ocular hypertension, glaucoma, and similar disorders refrain from inversion altogether. Whether normal individuals will suffer irreversible damage from inversion is uncertain, but it seems prudent to recommend that prolonged periods of inverted posturing be avoided.
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