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Biomedical subjects

W R Freeman

Publications and source records attributed to W R Freeman.

At least 163 records · Page 9Linked to original sources
PubMed1993

New ophthalmic lasers for the evaluation and treatment of retinal disease.

Ophthalmic lasers are used as diagnostic as well as therapeutic modalities in patients with retinal diseases. Recent advances in laser technology have allowed more convenient selection of wavelength and a wide variety of delivery systems is available to deliver the laser energy to the retina. In addition, newer lasers that disrupt and cut tissue will become available for use in patients with retinal diseases. The use of imaging lasers and lasers in combination with dyes selectively to enhance their effects have become useful in diagnosis and understanding of pathophysiology of diseases. These lasers will also be therapeutically useful. This manuscript delineates the new types of diagnostic and therapeutic lasers, new imaging dyes and techniques as they apply to retinal diseases as well as the principles of laser-tissue interaction as applied to the retina. This should allow the ophthalmologist who treats patients with retinal diseases to make more intelligent decisions regarding the use and acquisition of laser systems.

Animals↗
PubMed1993

Ocular examination and diagnosis in patients with the acquired immunodeficiency syndrome.

Ocular involvement is seen frequently and is an important source of morbidity in patients with the acquired immunodeficiency syndrome. We outline here the general skills of physical diagnosis valuable to primary care physicians or infectious diseases specialists in recognizing and evaluating ocular complaints in patients infected with the human immunodeficiency virus. We provide an overview of common ocular diseases in these patients, with an emphasis on signs and symptoms that aid in the differential diagnosis.

AIDS-Related Opportunistic Infections↗
PubMed1992

Visual dysfunction without retinitis in patients with acquired immunodeficiency syndrome.

Patients with human immunodeficiency virus infection may have noninfectious and infectious retinopathies, as well as clinical symptoms consistent with optic nerve dysfunction. Noninfectious acquired immunodeficiency syndrome-related retinopathy is seen in most patients with AIDS. Morphologic studies have shown that the number of retrobulbar optic nerve fibers in patients with AIDS is decreased compared to the number of optic nerve fibers in normal control eyes. To determine whether these patients had a visual dysfunction consistent with damage to the macula and optic nerve, 78 subjects (156 eyes) were studied using color-vision and contrast-sensitivity testing. The Farnsworth-Munsell 100-Hue color-vision test was performed on all subjects and age-corrected color-vision scores for all groups were compared. A significant decrease in color discrimination was found in the patients with AIDS (P less than .001). Contrast-sensitivity testing disclosed a deficit of contrast threshold in patients with AIDS at four of five spatial frequencies and in patients with AIDS-related complex at three of the five spatial frequencies examined. This study demonstrated a functional visual deficit in eyes without retinitis consistent with dysfunction of the macula or optic nerve in patients with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Morphometric comparisons of optic nerve axon loss in acquired immunodeficiency syndrome.

Axonal degeneration and diminution of the axonal population in the optic nerve have been documented in aging and in various neuro-ophthalmic conditions. We applied morphometric techniques to the postmortem examination of optic nerves obtained from patients with acquired immunodeficiency syndrome. Twelve optic nerves (eight from patients with AIDS and four from age-matched control eyes) were stained with paraphenylenediamine and morphometrically analyzed with a computer-assisted image and measurement system. Degeneration was often severe and was scattered throughout all of the AIDS-affected optic nerves. In the AIDS-affected optic nerves, the mean axonal population was markedly lower than the mean obtained from normal optic nerves (880,000 vs 1,507,000). Despite the approximate 40% loss of axons, mean axonal diameters were not markedly different, suggesting that no particular class of axon was especially susceptible to AIDS-associated degeneration. The extent and pattern of axonal loss in optic nerves of patients with AIDS suggest that the changes may not only be secondary to damage at the retina, but may reflect an AIDS-associated primary optic neuropathy.

Acquired Immunodeficiency Syndrome↗
PubMed1992

The prethreaded pupillary dilating (torpedo) suture for phakic and aphakic eyes.

A variety of methods for maintaining pupillary dilation for intraocular surgery have been advocated because pharmacologic agents may fail to maintain or adequately dilate the pupil. We have used a threaded needle to rapidly dilate the pupils of 19 aphakic, pseudophakic, or phakic eyes without damaging the lens or pseudophakos. This dilating suture can be constructed from available materials at low cost. We discuss the preparation of the suture and the techniques that allow rapid and reliable dilation during posterior vitrectomy or anterior segment surgery. Histologic studies were performed on rabbit eyes and demonstrated the position of the suture after performing pupillary dilation in phakic eyes. The technique has been used to dilate the pupils of phakic, aphakic, and pseudophakic patients without evidence of clinically significant complications.

Animals↗
PubMed1992

Atypical healing of cytomegalovirus retinitis. Significance of persistent border opacification.

PURPOSE: To analyze a phenomenon seen in patients with acquired immune deficiency syndrome (AIDS) with cytomegalovirus (CMV) retinitis undergoing systemic antiviral treatment: a persistent white border opacification on the edge of healed CMV retinitis. PATIENTS AND METHODS: The authors prospectively evaluated a population of 137 patients with AIDS and CMV retinitis during a 44-month period. Eleven patients (12 eyes) who were undergoing maintenance antiviral treatment were identified with an atypical healing response--the persistence of a white flat border opacification that did not advance for many weeks to months. Patient records and photographs were reviewed. Results of one autopsy were analyzed with histopathology and special stains. RESULTS: The persistent white edge maintained (without advancement or smoldering) for an average of 11.6 weeks (range, 4 to 41 weeks). This border opacification was not affected by reinduction treatment in the six patients to whom reinduction was given. Results from histopathologic examination of one patient with a persistent white border are presented: these results show that dead cytomegalic cells formed stable structures within the retina, causing white opacification that could be confused with active lesions. Immunoperoxidase stains identified CMV antigens. CONCLUSION: This persistent white border opacification, which does not advance or smolder, represents an important clinical entity that should be recognized during antiviral treatment for CMV retinitis. It can often be observed. If it is not recognized as a stable configuration, patients may undergo unnecessary reinductions with potentially toxic doses of antiviral medications.

AIDS-Related Opportunistic Infections↗
PubMed1992

Surgical repair of rhegmatogenous retinal detachment in immunosuppressed patients with cytomegalovirus retinitis.

The authors performed retinal reattachment surgery in 29 eyes of 24 patients with acquired immune deficiency syndrome virus with retinal detachment associated with cytomegalovirus (CMV) retinitis and documented the course of eight additional untreated eyes. Retinal detachment repair using vitrectomy, posterior hyaloid removal, and intraocular tamponade with silicone oil or SF-6 gas resulted in a total retinal reattachment rate of 76% and a macular attachment rate of 90% in one operation. The mean postoperative visual acuity (best corrected) was 20/60, but, in some patients, the visual acuity decreased because of progressive retinitis. Prophylactic laser photocoagulation of fellow eyes to surround CMV lesions did not appear to prevent retinal detachment. The mean postoperative survival was 37 weeks (range, 8 to 127 weeks). The surgical techniques used and pathophysiology of these retinal detachments are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Digital overlay of fluorescein angiograms and fundus images for treatment of subretinal neovascularization.

A system for comparing sequential fundus photographs and angiograms has been developed using a personal computer and commercially available image processing software. This process provides rapid results and a high degree of accuracy in image correlation, even when images come from different cameras with different magnifications. Though no concentrated effort was made to compare the superiority of this method to the manual technique, the value of the manual results is fully acknowledged, and this technique is offered as another method of achieving the same end. This technique can be used to determine the adequacy of treatment of subretinal neovascularization, recurrence of subretinal neovascularization in subsequent angiograms, pigment epithelial creep, and changes in fundus lesions.

Adult↗
PubMed1992

Evaluation of outpatient experience with vitreoretinal surgery.

The experience of 55 consecutive individuals undergoing outpatient vitreoretinal surgery was evaluated. Objective variables, including preoperative and intraoperative information, subjective postoperative pain, and discomfort were measured with a previously validated 100 mm visual analogue scale. Patients also ranked the overall experience. Average pain and discomfort scores in the recovery room were 21.8 and 22.6 and overnight were 26.7 and 30.4 (scale 0 to 100), respectively. Eighty eight per cent of subjects were satisfied with the experience. Elevated pain and discomfort scores were statistically correlated with scleral buckling, prolonged surgical or recovery room time, requirement for parenteral pain medications, and high intraocular pressure on the first postoperative visit. None of the patients needed further hospital treatment. This study suggests that vitreoretinal surgery in an appropriately selected population does not require routine inpatient care.

Adult↗
PubMed1992

Role of HIV and CMV in the pathogenesis of retinitis and retinal vasculopathy in AIDS patients.

Cotton-wool spots and cytomegalovirus (CMV) retinitis are seen frequently in AIDS patients. Human immunodeficiency virus (HIV) infection of the retina has been proposed as a mechanism for the high incidence of retinal pathology. An autopsy study of the eyes from 25 consecutive cases of AIDS was performed using gross examination, light microscopy, trypsin digestion of retinal vasculatures, and immunohistochemistry to evaluate the possible role of HIV, as well as CMV, in the pathogenesis of retinitis and retinal vasculopathy. Brain tissue was studied in the first 20 of these cases to evaluate any correlation between retinal and central nervous system pathology. CMV retinitis was observed in 15 cases (60%). Cotton-wool spots were seen in nine cases (36%). CMV encephalitis was detected in four cases, whereas HIV encephalitis was noted in five cases. We were unable to demonstrate a correlation between CMV retinitis and CMV encephalitis. However, the number of cases studied was small, and the frequency of CMV encephalitis was low. On the other hand, bilateral CMV retinitis demonstrated a correlation to HIV encephalitis (P less than 0.005, Fisher's exact test). HIV infection of the retina was not detected by typical morphologic changes or immunohistochemistry. Immunohistochemistry localized CMV infection solely to areas of active retinitis. These findings suggest that bilateral CMV may serve as a marker of HIV encephalitis, possibly indicating a severely immunodepressed state.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1991

Hemorrhagic choroidal detachment with anterior vitreoretinal adhesions.

We present three cases of large intraoperative or postoperative hemorrhagic choroidal detachment with subsequent adherence of the retina to anterior segment structures. Surgical management involved bimanual vitrectomy through anterior sclerotomy sites and dissection within the anterior segment. Successful retinal reattachment was achieved in two of these cases (18-months' follow up). In the third case, the retina remained attached for 4 months but then redetached.

Adolescent↗
PubMed1990

Experimental endoretinal biopsy.

We performed transvitreal endoretinal biopsy in rabbit eyes to develop a reliable and safe technique to obtain retinal specimens from attached retina. Pars plana vitrectomy without lensectomy was followed by injection of Ringer's solution into the subretinal space to produce a focal retinal detachment. The apex of the focal detachment was excised by intraocular scissors and removed from the eye by pneumohydraulic expulsion. A fluid-air exchange reattached the retina. The biopsy sites were evaluated clinically and by light and electron microscopy at regular intervals up to 20 weeks postoperatively. The initial five procedures were performed without heparin in the infusion fluid, and they were complicated by severe fibrin reaction and early retinal detachment. Of the remaining 17 eyes, 15 were without intraoperative complication and maintained attached retinas. The biopsy site developed an early ring of hyperpigmentation along the border, and the biopsy bed became increasingly hyperpigmented because of cytoplasmic hyperplasia and hypertrophy of the pigment epithelium. Epiretinal membranes and subretinal neovascularization were observed histologically. Retinal biopsy specimens were reproducible and suitable for diagnostic studies.

Animals↗
PubMed1990

Magnetic resonance imaging in the evaluation of vitreoretinal disease in eyes with intraocular silicone oil.

Media opacification in eyes filled with silicone oil makes the evaluation of recurrent retinal detachment difficult. Ultrasonography through silicone oil is subject to significant imaging artifacts. We performed magnetic resonance imaging on six patients with unilateral intravitreal silicone oil to determine if the technique would detect detached retina and subretinal oil. All patients had undergone pars plana vitrectomy with silicone oil injection for proliferative vitreoretinopathy; five patients had encircling solid silicone scleral buckles. In five patients the media were clear, and ophthalmoscopic findings were correlated with magnetic resonance findings. Four patients had recurrence of inferior retinal detachment; magnetic resonance imaging demonstrated subretinal oil in three of these patients. One patient had a concentric, shallow, anterior retinal detachment; magnetic resonance scanning demonstrated a globular hyperintensity suggestive of subretinal oil. In the sixth patient, who had an opaque cornea, magnetic resonance imaging suggested that the retina was attached preoperatively; this was confirmed at subsequent surgery. A chemical shift artifact was helpful in defining the contour of retinal detachments and the presence of subretinal oil by outlining the silicone oil within the eye.

Eye↗
PubMed1990

Longitudinal study of cytomegalovirus retinitis in acquired immune deficiency syndrome.

The authors prospectively evaluated 67 consecutive patients with the acquired immune deficiency syndrome (AIDS) and cytomegalovirus (CMV) retinitis during a 33-month period to assess the clinical patterns of retinal infection, efficacy of treatment, long-term survival, and relationship of retinitis to immune function. Immediately sight-threatening retinitis presented in six patients (9%) with peripapillary disease; primary foveal infection was not observed. Eighty-seven percent of patients were treated with ganciclovir. Thirty-nine patients (58%) presented with unilateral disease and contralateral infection developed in 15% of those while on ganciclovir. Smoldering (incompletely responsive) retinitis was seen in 33% of the 21 patients whose retinitis progressed while receiving ganciclovir. Progression of treated retinitis was associated with a lower lymphocyte count (P = 0.04). Median survival after diagnosis of CMV retinitis was 8 months. This represents the largest reported prospective study of CMV retinitis and indicates that (1) CMV infrequently poses an immediate threat to vision on presentation, (2) response to therapy may be related to immune function, and (3) smoldering retinitis should be recognized as an important clinical entity associated with treatment failure.

Acquired Immunodeficiency Syndrome↗