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Biomedical subjects

T S Stevens

Publications and source records attributed to T S Stevens.

At least 19 recordsLinked to original sources
PubMed2001

Treatment of submacular hemorrhage with low-dose intravitreal tissue plasminogen activator injection and pneumatic displacement.

OBJECTIVE: To investigate the safety and efficacy of low-dose intravitreal tissue plasminogen activator (tPA) and an expansile gas bubble in displacing submacular hemorrhage in patients with age-related macular degeneration (ARMD). PATIENTS AND METHODS: We reviewed retrospectively the medical records of 14 consecutive patients with ARMD from 1 academic center who received low-dose intravitreal tPA (18-50 microg) and expansile gas (0.3-0.4 mL of perfluoropropane) for thrombolysis and displacement of submacular hemorrhage. After the procedure, patients maintained face-down positioning for 1 to 3 days. MAIN OUTCOME MEASURES: Displacement of blood from the fovea, early and final visual acuity, and toxicity of tPA. RESULTS: Submacular blood was completely displaced from the fovea in 10 (71%) of the 14 patients and partially displaced in 3 (21%). In 1 patient, no displacement occurred. Early (<2 months) postoperative visual acuity improved by 2 or more lines in 8 patients (57%). With a mean follow-up of 7.7 months, 2 (15%) of 13 patients maintained 2 or more lines of improvement and 69% (9 patients) maintained preoperative visual acuity. No clinical evidence of retinal toxicity was seen at this low-dose of tPA. CONCLUSIONS: Doses of intravitreal tPA ranging from 18 to 50 microg and an expansile gas bubble are safe and effective in displacing submacular hemorrhage in patients with ARMD. Final visual acuity was limited by the underlying presence of end-stage ARMD.

Aged↗
PubMed1997

Occult choroidal neovascularization in age-related macular degeneration. A natural history study.

OBJECTIVE: To explore morphological and vision changes in untreated eyes with subfoveal choroidal neovascularization (CNV) that have poorly demarcated boundaries. DESIGN: Analysis of photographs of untreated patients with poorly demarcated occult CNV participating in a prospective clinical trial evaluating laser treatment compared with observation. SETTING: Two tertiary retinal referral centers. PATIENTS: Symptomatic individuals with poorly demarcated subfoveal occult CNV associated with age-related macular degeneration. MAIN OUTCOME MEASURES: Change in size of lesion, development of classic CNV, change in vision, and development of subretinal fibrosis. RESULTS: During follow-up (9-12 months), 32% of the occult choroidal neovascular lesions more than doubled their original size. Classic CNV developed in 52% of eyes that started without it. The median loss in visual acuity was 2.5 lines. Eyes with classic CNV or subretinal blood or both at baseline developed subretinal fibrosis more frequently and lost more visual acuity, but not to a statistically significant degree. CONCLUSIONS: The morphological changes of eyes with subfoveal occult CNV in which the boundaries are poorly demarcated in variable; the presence of subretinal blood or a component of classic CNV may influence the prognosis for further loss of vision.

Aged↗
PubMed1996

Macular scatter ('grid') laser treatment of poorly demarcated subfoveal choroidal neovascularization in age-related macular degeneration. Results of a randomized pilot trial.

OBJECTIVES: To determine the effects of macular scatter ("grid") laser photocoagulation compared with observation on the visual function of eyes with subfoveal choroidal neovascularization (CNV) that has poorly demarcated boundaries and to provide preliminary data for the evaluation of the feasibility and design of a larger, definitive trial. DESIGN: Randomized pilot clinical trial. SETTING: Two tertiary care retinal referral practices. PATIENTS: Symptomatic individuals with subfoveal CNV secondary to age-related macular degeneration in whom fluorescein angiography showed occult CNV with poorly demarcated boundaries; classic CNV was allowed but did not need to be present for entry into the study. MAIN OUTCOME MEASURE: Change in visual acuity from baseline to specified time periods. RESULTS: Fifty-two eyes were assigned to observation. Fifty-one eyes were assigned randomly to treatment consisting of macular scatter ("grid") laser photocoagulation to the area of CNV. The treatment protocol for 8 of these eyes also included confluent laser photocoagulation to areas of classic CNV. The average visual acuity decrease from baseline was greater in the treated than in the observed group. The difference between these groups was greatest within the first year after study enrollment. At 24 months, slightly more than 40% of the eyes in each group had lost 6 or more lines of visual acuity. Similar results were noted for the subgroup of eyes initially with angiographic features of occult CNV but no classic CNV. CONCLUSIONS: These short-term study results suggest that macular scatter ("grid") laser treatment is not beneficial and is possibly harmful compared with observation for symptomatic subfoveal CNV with poorly demarcated boundaries in age-related macular degeneration. With or without treatment, a significant proportion of these patients are at risk of severe visual loss within 2 years of seeking treatment, even when the eye initially has occult CNV and no classic CNV.

Aged↗
PubMed1991

Clinicopathologic correlation of diode laser burns in monkeys.

One hundred twenty-five retinochoroidal photocoagulation burns, produced by a transpupillary diode laser (810 nm) in six eyes of three cynomolgus monkeys, were evaluated by clinicopathologic correlation for up to 9 weeks after laser treatment. Diode burns of clinical grade 2 strength were comparable to those described for argon laser. However, diode burns of clinical grade 3 strength produced choroidal changes more intense than those described for argon laser. Where present underneath photocoagulation sites, ciliary nerves in choroid or sclera consistently showed scarring. Prospective randomized controlled clinical trials to document possible clinical equivalence or superiority of diode treatment have not yet been performed. Potential clinical advantages of the diode laser include its weight, size, durability, price, absence of visible flash, and its ability to produce burns that profoundly affect the choroid.

Animals↗
PubMed1990

Immunocytochemical study of an eye with proliferative vitreoretinopathy and retinal tacks.

After an eye-wall resection for a choroidal melanoma, a 32-year-old woman had subsequent retinal detachment with proliferative vitreoretinopathy (PVR), and an unsuccessful attempt at repair with retinal tacks. Gross and light-microscopic examination of the globe revealed a total retinal detachment with extensive preretinal and subretinal membranes. The membranes surrounded the tack heads and extended in taut bands to form a tractional detachment of the pars plana. The membranes contained glial and nonglial cells. The glial cells immunolabeled for glial fibrillary acidic protein (GFAP), carbonic anhydrase-C (CA-C), vimentin, and glutamine synthetase (GS), thus suggesting that they were Müller's cells. While the tacks did not seem to cause PVR, in this case they may have provided an anchoring point from which membranes were able to exert traction on the retina and pars plana.

Adult↗
PubMed1989

Immunostaining of preretinal membranes for actin, fibronectin, and glial fibrillary acidic protein.

The frequency and extent of immunostaining for actin, fibronectin (FN), and glial fibrillary acidic protein (GFAP) were determined in 37 preretinal membranes (PRMs) obtained at vitrectomy from 35 patients with proliferative diabetic retinopathy (PDR) (n = 16), proliferative vitreoretinopathy (PVR) (n = 18), or idiopathic macular pucker (MP) (n = 3). All three proteins were detected in the vast majority of specimens (actin, 86%; FN, 95%; GFAP, 96%), although the extent of staining varied for each. Actin-FN co-localization was observed in all diagnostic groups on comparison of adjacent sections and in double-labeled sections. The extent of actin staining did not correlate with clinical grading of PRM contraction. In PDR membranes, FN staining was low overall, but proportional to the vascular content of the PRM. Fibronectin staining of PVR membranes was greater, and extensive even in avascular specimens. In MP membranes, most cells were GFAP-positive, whereas in PDR and PVR specimens, GFAP staining was variable. The lack of correlation of clinical contractility and membrane composition, as studied in this article by immunostaining, indicates that other factors must play significant roles in determining membrane behavior.

Actins↗
PubMed1988

Latent disseminated blastomycosis with choroidal involvement.

A 36-year-old man developed blurred vision and a cough five months after traveling to an area from where a large outbreak of acute blastomycosis had been reported. Examination revealed a left choroidal lesion in the macular region, skin lesions on the right calf, and a left lung apical infiltrate. Histopathologic examination of the skin lesion demonstrated a granulomatous inflammation and broad based, budding yeast characteristic of Blastomyces dermatitidis. Amphotericin B therapy produced a rapid resolution of both choroidal and pulmonary lesions. During a six-month follow-up, there was no evidence of recurrence.

Adult↗
PubMed1988

Posterior ciliary-artery occlusion after subcutaneous silicone-oil injection.

Visual loss occurred after subcutaneous silicone-oil injection for cosmetic purposes. To our knowledge, this is the first instance of amaurosis caused by a subcutaneous foreign-material injection that spared the central retinal artery and affected portions of the posterior ciliary-artery distribution, including a probable cilioretinal artery. The visual-field defects produced allow a rare opportunity to view the distribution of the human posterior ciliary-artery circulation by means of this in vivo pathologic embolic process. The facial arterial anatomy pertinent to ocular embolism is also discussed.

Adult↗
PubMed1985

Diagnosis and pathogenesis of retinal pigment epithelial tears.

Ten cases of retinal pigment epithelial tears were observed in eight patients with serous pigment epithelial detachments associated with age-related macular degeneration. Eight of the ten tears were spontaneous and all occurred at the detachment margin. The resulting area of exposed choroid was sometimes initially mistaken for pigment epithelial atrophy. In two cases it was misdiagnosed as choroidal neovascularization and treated with laser photocoagulation. All but two patients suffered severe visual loss.

Aged↗
PubMed1984

Actin filaments in contracting preretinal membranes.

In 14 patients, preretinal membranes, causing retinal traction and severe visual impairment, were removed by vitrectomy and evaluated by light and electron microscopy using myosin subfragment-1 to stain actin filaments. Eight membranes were of vascular origin, six of nonvascular origin. All but one contained bundles of oriented actin filaments within a number of their nonvascular stroma cells, suggesting that the contractile protein action may have been involved in their clinically observed contraction.

Actins↗
PubMed1981

Actin filaments in diabetic fibrovascular preretinal membrane.

A vitrectomy specimen from a diabetic patient was studied by light and electron microscopy using myosin subfragment 1 to decorate and identify actin filaments. The patient had proliferative diabetic retinopathy, a shrinking fibrovascular preretinal membrane associated with retraction of the thickened posterior hyaloid, and a localized traction retinal detachment. The fibrovascular tissue comprised normal mature collagen, few cells, and occasional blood vessels. The cells contained numerous thick bundles of the contractile protein, actin. We suggest that actin may have been involved in the contraction phenomena observed clinically and that membrane contraction might be blocked by pharmacologic treatment.

Actins↗
PubMed1981

Diabetic maculopathies.

Pathological changes in the diabetic macula are a frequent cause of visual loss. They can be classified as intraretinal or vitreoretinal maculopathies. The intraretinal ones are due to hyperpermeable retinal capillaries or retinal vascular shut-down. They appear clinically as macular edema, exudative maculopathy, fluorescein dye leak maculopathy, or ischemic maculopathy. When edema and exudation cause or threaten to cause significant visual loss they are treated by photocoagulation. The vitreoretinal maculopathies are due to traction resulting from (1) the formation of vitreoretinal adhesions with subsequent vitreous shrinkage, (2) the formation of bands or membranes from one retinal area to another and their subsequent shrinkage, or (3) epiretinal membrane formation and contraction. They appear clinically as epiretinal membranes, retinal wrinkling, macular heterotopia, or traction detachment of the macula. Traction detachment and contracted epiretinal membranes associated with significant visual loss are treated by vitreous surgery; an effective treatment for macular heterotopia has not been demonstrated.

Adult↗
PubMed1978

Pigmented paravenous retinochoroidal atrophy.

A patient with paravenous pigmented chorioretinal atrophy is presented. A differential diagnosis and review of the literature are discussed. Fluorescein angiography confirms the presence of a widespread paravenous retinal pigment epithelial defect with minimally affected choroidal vasculature. The visual fields are constricted in proportion to the extent of the pigmentary abnormality. The electro-oculogram and electroretinogram show reduced responses indicative of a more extensive abnormality than is visible ophthalmoscopically. The etiology and natural course of this entity are unknown.

Adolescent↗
PubMed1976

Retinal vascular changes of incontinentia pigmenti.

Of 19 patients with incontinentia pigmenti, seven had a bizarre retinal anomaly that consisted of a zone of abnormal arteriovenous connections and preretinal fibrotic tissue at the temporal equator, with no perfusion peripheral to it. In one patient, the vascular changes progressed and required photocoagulation. This retinal lesion may represent an early stage of the pseudoglioma that so commonly is reported with this skin disease. Incontinentia pigmenti should be considered in the differential diagnosis of retinal vascular disease in girls and women of any age.

Adolescent↗