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Biomedical subjects

F H Lambrou

Publications and source records attributed to F H Lambrou.

At least 19 recordsLinked to original sources
PubMed1998

Surfing-related ocular injuries.

PURPOSE: This report evaluates the clinical characteristics of surfing-related ocular trauma to learn the nature of such injuries and propose possible preventive measures. METHODS: The authors reviewed 11 cases of surfing-related eye injuries caused by direct trauma from the surfboard, studying their mechanism of injury, the associated ocular complications, and the anatomic and visual outcomes of surgical repair. RESULTS: Surfing-related ocular injuries occurred exclusively in young males (mean age, 24.8 years; range, 14-37 years). The mechanism of injury most frequently responsible was impact with the sharp nose of the surfboard following a fall. Serious posterior segment complications were observed in all 11 patients, with nine patients suffering ruptured globes. Despite immediate medical attention, five patients did not recover ambulatory levels of visual acuity (>5/200). CONCLUSIONS: Surfing-related ocular trauma presenting to the retinal specialist typically leaves the patient with a permanent visual disability. Important factors contributing to these high-velocity injuries include the sharply pointed nose of the surfboard and the leash keeping the surfer in close proximity to the board following a fall. A simple modification in surfboard design such as blunting the sharp nose of the surfboard, or appropriate protective guards fitted over the surfboard nose, should lessen the severity of such injuries.

Adolescent↗
PubMed1992

Management of dislocated lens fragments during phacoemulsification.

BACKGROUND: Dislocation of nuclear lens fragments during phacoemulsification can lead to a high incidence of glaucoma, uveitis, and poor visual acuity. The correct approach to these patients is uncertain. The authors report on eight patients who underwent pars plana vitrectomy with removal of lens fragments. METHODS: Charts of eight consecutive patients who developed dislocation of nuclear lens fragments into the vitreous cavity during phacoemulsification were retrospectively reviewed. All patients underwent a standard three-port pars plana vitrectomy with removal of the dislocated nuclear fragments by pars plana fragmentation. After the vitrectomy, the retina was inspected with indirect ophthalmoscopy. Tears were treated with cryopexy. A fluid-air exchange and scleral buckle were performed when indicated. RESULTS: Retinal tears were located at the vitreous base in four of eight patients. After vitrectomy, visual acuity improved in all patients, with 7 of 8 patients achieving visual acuity of 20/40 or better. The type of pseudophakia did not influence the final visual acuity. There were no cases of glaucoma, uveitis, or macular edema with up to 22 months of follow-up. CONCLUSIONS: These results suggest that large nuclear fragments dislocated into the posterior segment during phacoemulsification can be removed safely with pars plana vitrectomy and lensectomy with an excellent visual prognosis. Attempts to remove lens fragments during the phacoemulsification through an anterior wound should be avoided because of excessive vitreous traction, leading to retinal break formation.

Aged↗
PubMed1991

Sudden blindness associated with central nervous symptoms in a hemodialysis patient.

Purtscher's-like retinopathy as a cause of sudden blindness in hemodialysis patients is not widely known. This is believed to occur secondary to leukoembolization to retinal arterioles following complement activation. We describe a patient who developed sudden but reversible loss of vision on hemodialysis associated with varying reversible neurological signs and symptoms which we felt may have been a manifestation of leukoembolic aggregates lodging in the arterioles of the retina and central nervous system circulations.

Adult↗
PubMed1989

Obstruction of the trabecular meshwork by retinal rod outer segments.

Rod outer segments (ROS) have been described in the anterior chamber of patients with the Schwartz syndrome (retinal detachment, uveitis, and glaucoma). The effect of ROS on aqueous outflow was studied by intracameral injection of ROS in human eye bank eyes and in vivo in the cat. Injection of 10(8) ROS in eye bank eyes (n = 8) caused a 19.7% decrease in outflow facility. This was significantly different than in control eyes (n = 8), where the outflow facility decreased 5.2%. Injection of intracameral ROS in the cat resulted in a rise in intraocular pressure (IOP) from a baseline of 19.7 +/- 1.3 mm Hg to a peak of 30.0 +/- 0.7 mm Hg at 24 hours. By 48 hours, IOP returned to baseline. Control injection did not cause a change in IOP. Electron microscopy of the cat trabecular meshwork revealed occlusion of the intratrabecular spaces by ROS with little evidence of inflammatory activity.

Aged↗
PubMed1989

Mechanisms of intraocular pressure elevation after pars plana vitrectomy.

A prospective study of 222 consecutive patients undergoing pars plana vitrectomy was done to determine the incidence and mechanisms of postoperative intraocular pressure (IOP) elevation. Within 48 hours of surgery, postoperative IOP increased by at least 5 to 22 mmHg in 136 eyes (61.3%) and to 30 mmHg or more in 79 eyes (35.6%). Presumed mechanisms of open-angle glaucoma included intraocular gas expansion (28.4%), inflammatory trabecular meshwork obstruction (4.5%), silicone oil-related glaucoma (3.6%), and erythroclastic glaucoma (2.2%). Closed-angle mechanisms included pupillary block glaucoma (6.8%) and ciliary body edema (3.6%). Factors which were associated with postvitrectomy pressure elevation included placement of a scleral buckle, either intraoperatively (P = 0.003) or before vitrectomy (P = 0.001), intraoperative scatter endophotocoagulation (P = 0.041), intra-operative lensectomy (P = 0.024), and development of postoperative fibrin membranes (P = 0.038). Surgery was required to lower IOP or relieve pupillary block in 25 eyes (11.3%).

Adolescent↗
PubMed1989

Vitrectomy when asteroid hyalosis prevents laser photocoagulation.

Asteroid hyalosis is a relatively common disorder of the vitreous that rarely causes visual impairment. However, funduscopic examination and laser photocoagulation can be difficult because of reflections off the asteroid bodies. Although vitrectomy is rarely indicated for impaired visual acuity, we report three cases in which pars plana vitrectomy was necessary to permit required retinal laser photocoagulation. In two patients with proliferative diabetic retinopathy and a third patient with subretinal neovascularization marked asteroid hyalosis precluded photocoagulation by standard techniques.

Aged↗
PubMed1988

Cryopexy of the vitreous base in the management of peripheral uveitis.

We reviewed 27 consecutive eyes with peripheral uveitis and vitreous base neovascularization that had been treated with cryopexy and followed up for a median of 4.5 years. During the follow-up period, 21 eyes (78%) remained quiescent, whereas five eyes (18%) demonstrated intermittent inflammation, although only one of these eyes progressed to a traction retinal detachment. One eye (4%) eventually atrophied; however, this was believed to be a result of the ongoing uveitis rather than the cryopexy. The treated eyes had an average improvement of three lines in Snellen visual acuity. We found that corticosteroid therapy remains the primary treatment modality for active inflammation, and vitreous base cryopexy should be reserved for those cases which are resistant to corticosteroids, and which demonstrate active neovascularization.

Adolescent↗
PubMed1988

Treatment of postvitrectomy fibrin formation with intraocular tissue plasminogen activator.

Twenty-five micrograms of human recombinant tissue plasminogen activator (tPA) was injected intracamerally into the eyes of three aphakic patients who developed severe intraocular fibrin formation within 24 hours after vitrectomy surgery. Fluid obtained from gas-fluid exchange specimens taken 24 hours after tPA injection was analyzed for tPA by an enzyme-linked immunosorbent assay and a spectrophotometric solid-phase fibrin assay. In each of the three patients, complete fibrin resolution occurred within four hours after the tPA injection. There were no complications associated with the intraocular tPA injections. There was measurable tPA activity 24 hours after the initial injection ranging from 0.23 to 1.4 micrograms. In contrast, tPA was undetectable in gas-fluid exchange specimens obtained from seven patients who did not receive intraocular tPA injections. Intraocular tPA is an effective means of treating postvitrectomy fibrin formation in selected aphakic patients.

Adolescent↗
PubMed1988

A new technique for subchoroidal implantation of experimental malignant melanoma.

A new technique for implanting Greene hamster amelanotic melanoma cells into the rabbit eye is described. The technique involves the deposition of a tumor fragment into the subchoroidal space via a transvitreal approach. Thirty rabbit eyes were implanted with 26 successful tumor growths producing solitary choroidal nodules. This technique offers the advantages of rapid implantation, the ability to precisely choose the site of implantation including posterior sites, and eliminates the need for a large scleral incision.

Animals↗
PubMed1987

Treatment of experimental intravitreal fibrin with tissue plasminogen activator.

We produced experimental intravitreal fibrin clots in rabbits that had previous gas compression of the vitreous or intact vitreous. Twenty-four hours after production of fibrin, the eyes were injected with 25 micrograms of tissue plasminogen activator or physiologic irrigation solution. In the gas compression group (n = 11), all tissue plasminogen activator-treated eyes cleared within six hours of injection; complete clearing was not seen until six days in the physiologic irrigation solution-treated eyes (n = 9). A similar response was seen in the intact vitreous group. No evidence of toxicity was observed as measured by slit-lamp biomicroscopy, intraocular pressure, corneal thickness, electroretinography, or histopathologic examination.

Animals↗
PubMed1987

Use of tissue plasminogen activator in experimental hyphema.

Tissue plasminogen activator (tPA) is a fibrin-specific fibrinolytic agent that has recently been shown to be effective in accelerating the clearance of fibrin clots from the rabbit anterior chamber. We studied the effect of intracameral tPA on the clearance of experimental hyphema in the rabbit. Fifteen eyes were treated with an intracameral injection of tPA (1800 IU), 11 eyes were treated with a physiologic saline solution (PS) injection, and 16 eyes received no injection. Total hyphemas treated with tPA showed 80% clearance within 24 hours, while eyes treated with PS and untreated eyes cleared in 14 days. Measurement of corneal thickness revealed the tPA-treated eyes to have less corneal edema than eyes treated with PS and untreated eyes. There was no difference in intraocular pressure. The results indicate that tPA is effective in accelerating the clearance of experimental hyphema.

Animals↗
PubMed1987

Secondary surgical management of expulsive choroidal hemorrhage.

Eight cases of expulsive hemorrhage with herniation of intraocular contents were managed with secondary procedures after initial operative closure of the eye. Two eyes with giant retinal tears and clear vitreous were treated with photocoagulation alone; each regained 20/200 visual acuity. Vitreous hemorrhage, traction retinal detachment, or rhegmatogenous retinal detachment was an indication for surgery in six eyes. Vitrectomy, choroidal drainage with simultaneous intraocular infusion, and scleral buckling restored useful vision in two eyes. In cases without vitreous hemorrhage or retinal detachment, conservative management may yield good results, while intraocular surgery may salvage useful vision in more complicated cases.

Adult↗
PubMed1987

Effect of silicone oil on experimental traction retinal detachment.

The use of silicone oil as a retinal tamponade in the treatment of proliferative vitreoretinopathy is often complicated by membrane reproliferation. We studied the development of traction retinal detachments following the intravitreal injection of 15,000 retinal pigment epithelial cells in silicone-, perfluoropropane-, and fluid-filled rabbit eyes. By 28 days a higher proportion of silicone-filled eyes (83%) had severe proliferative vitreoretinopathy than either the perfluoropropane-filled (30%) or fluid-filled (10%) eyes. An in vitro proliferation assay using the vitreous samples showed that the silicone-filled vitreous had increased mitogenic activity for retinal pigment epithelial cells compared with the gas-filled or fluid-filled vitreous. Silicone oil appears to increase proliferation by stimulating the release of more or different mitogenic factors as well as by concentrating active factors into a smaller volume near the retina.

Animals↗
PubMed1987

Intraocular fibrinolysis with recombinant human tissue plasminogen activator. Experimental treatment in a rabbit model.

Intraocular fibrin formation following ocular surgery is a potentially binding problem. Current therapy for this postoperative fibrin response is often ineffective. In the rabbit, we developed a quantitative reproducible model for intraocular fibrin deposition. Using this model, we have tested the efficacy of human tissue plasminogen activator (tPA) in promoting intraocular fibrinolysis. Citrated rabbit plasma (0.2 mL) was injected intracamerally following paracentesis, resulting in fibrin clot formation within three hours. The fibrin clots were stable for four days, and then slowly lysed over the next four days. Approximately 24 hours after clot formation, various concentrations of human tPA were injected intracamerally. The time taken for clot lysis was dose dependent, with 1800 IU of tPA producing clot lysis in three hours. Toxicity, as measured by intraocular pressure, corneal thickness, inflammation, or cataract formation, was minimal.

Animals↗
PubMed1987

Wound dehiscence following cataract surgery.

We retrospectively examined ophthalmic surgery at two teaching hospitals from 1982 to 1985 to determine the incidence, cause, treatment, and outcome of wound dehiscence following cataract surgery. In the 1276 cataract procedures performed during this period, 18 patients (1.4%) underwent repair of wound dehiscence. Thirty-one percent of patients with dehiscence had had cataract extraction on subluxed traumatic cataracts; trauma also caused 69% of the dehiscences. Posterior chamber lenses remained in place in 88% of cases. Seventy-seven percent regained 20/40 or better visual acuity following repair.

Adult↗
PubMed1985

The production and mechanism of ghost cell glaucoma in the cat and primate.

Fresh human ghost blood cells (GBCs) have been shown to cause increased resistance to outflow in enucleated human eyes. In addition, glutaraldehyde-fixed GBCs can cause glaucoma in the rabbit and primate in vivo. The present study shows for the first time that fresh autologous GBCs can cause an acute in vivo rise of intraocular pressure when injected into the anterior chambers of the cat and primate. This rise was of greater magnitude and longer duration than that caused by the injection of a greater number of pliable, fresh red blood cells. It has been theorized that ghost cell glaucoma (GCG) is due to cellular obstruction of the intertrabecular spaces by the nonpliable GBCs. Histologic results from the present study confirm this belief. No evidence of significant trabecular meshwork degeneration or significant GBC phagocytosis was seen.

Animals↗