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Biomedical subjects

B L Lam

Publications and source records attributed to B L Lam.

At least 55 records · Page 3Linked to original sources
PubMed1993

Chiasmal compression from fat packing after transsphenoidal resection of intrasellar tumor in two patients.

After transsphenoidal resection of a pituitary (or other) tumor, the remaining intrasellar cavity, and sphenoid sinus are usually packed with exogenous fat or muscle to prevent cerebrospinal leak and prolapse of the optic chiasm into an empty sella. We treated two patients in whom chiasmal compression occurred postoperatively because of packing of fat. In one patient, the expected visual improvement in the postoperative period was suboptimal. The subsequent removal of fat resulted in total visual recovery. In the other patient, chiasmal compression persisted from intrasellar fat and residual tumor. Iatrogenic compression of the optic nerves or chiasm should be considered in all patients in whom visual recovery is incomplete.

Adipose Tissue↗
PubMed1993

Elevated serum sialic acid in idiopathic acute iridocyclitis.

We measured the serum levels of sialic acid in 12 patients with idiopathic acute iridocyclitis and 18 normal controls. Sialic acid levels were significantly elevated in the patients with idiopathic acute iridocyclitis. Since animal studies have shown that intraocular inflammation alone cannot elevate serum level of sialic acid, the result of our study suggest that idiopathic acute iridocyclitis may be a multiorgan disease with systemic effects.

Acute Disease↗
PubMed1993

Iris crystals in chronic iridocyclitis.

Iris crystals in three patients with idiopathic iridocyclitis, Fuchs' heterochromic iridocyclitis, and iridocyclitis associated with systemic pseudolymphoma are described. Two patients had iris crystals in one eye, and the other patient had bilateral involvement. The number of iris crystals in each eye ranged from one to multiple crystals. Iris crystals were minute and refractile and glistened with light; they have previously been reported to be Russell bodies and to be associated with hypergammaglobulinaemia. However, two of the patients, who underwent serum protein electrophoresis, did not demonstrate hypergammaglobulinaemia.

Adult↗
PubMed1992

Optic neuropathy in Hodgkin's disease.

Hodgkin's disease is a rare cause of infiltrative optic neuropathy, which typically evolves late in the disease course. We managed an unusual case of isolated optic neuropathy in a 21-year-old man occurring during clinical remission from Hodgkin's disease. Radiotherapy and treatment with high-dose systemic corticosteroids resulted in dramatic improvement in vision. Even without other evidence of recurrent disease, acute-onset optic neuropathy in a patient with a history of a lymphoproliferative disorder should raise the question of a reemergence of the malignancy.

Adult↗
PubMed1992

High incidence of sympathetic ophthalmia after contact and noncontact neodymium:YAG cyclotherapy.

BACKGROUND: Two cases of sympathetic ophthalmia occurring after noncontact neodymium:YAG (Nd:YAG) cyclotherapy have previously been reported. In each case, the patient had undergone filtering surgery in the exciting eye. Although in each case Nd:YAG cyclotherapy was the last surgery performed, the inciting event of sympathetic ophthalmia was unclear. METHODS: The authors studied three additional patients who developed sympathetic ophthalmia after Nd:YAG cyclotherapy for glaucoma. RESULTS: Two patients developed sympathetic ophthalmia 4 months after noncontact Nd:YAG cyclotherapy, and 1 patient developed sympathetic ophthalmia 18 months after contact Nd:YAG cyclotherapy. All patients had previous cataract extractions but no filtering surgery in the exciting eye. Clinical features included chronic iridocyclitis, choroidal folds, Dalen-Fuchs nodules, and optic disc edema. Combining these cases with the two previously reported cases, the incidence of sympathetic ophthalmia at our institution thus far is 5.8% (4 of 69) and 0.67% (1 of 150) after noncontact and contact Nd:YAG cyclotherapy, respectively. CONCLUSIONS: The incidence of sympathetic ophthalmia after Nd:YAG cyclotherapy is high compared with other ocular procedures. The clinician should vigilantly monitor patients after Nd:YAG cyclotherapy and report additional cases that may have occurred at other institutions.

Aged↗
PubMed1992

Effect of mydriasis on visual field area in retinitis pigmentosa.

PURPOSE: The effect of mydriasis on Goldmann visual field area in patients with retinitis pigmentosa has not been suitably defined. The aim of this study is to determine whether visual field area in these patients varies with pharmacologic mydriasis. METHODS: Fifteen adult patients with retinitis pigmentosa were studied prospectively. Goldmann visual fields with II4e and V4e isopters were obtained in both eyes before and after full pharmacologic mydriasis of the right eye. The isopter areas were quantified and analyzed to determine the effect of mydriasis on visual field area. RESULTS: The difference in the right eye isopter areas was compared with the difference in the left eye isopter areas using paired t tests, where the differences were computed from areas obtained before and after dilation of the right eye. Mydriasis had no significant effect on the visual field in terms of isopter area difference (II4e, P = 0.87; V4e, P = 0.45) and percent change in isopter area (II4e, P = 0.81; V4e, P = 0.24). CONCLUSION: Pharmacologic mydriasis had no appreciable effect on the Goldmann visual field area in a selected group of patients with retinitis pigmentosa. These findings suggest that visual fields of such patients obtained in the dilated or undilated state can be meaningfully compared.

Adult↗
PubMed1992

Pseudotumor cerebri from cranial venous obstruction.

Dural sinus hypertension from cerebral venous outflow impairment is a cause of pseudotumor cerebri. The authors documented six such patients: two with unilateral neck dissection, one with surgical ligation of the dominant sigmoid sinus, two with thrombosed central intravenous catheterization, and one with dural sinus thrombosis. The site of cerebral venous outflow obstruction was variable and identified in three patients with computed tomography, conventional magnetic resonance imaging, magnetic resonance angiography, and/or angiography. Magnetic resonance angiography used in two patients characterized the venous flow pattern and identified the site of obstruction, confirming magnetic resonance angiography as an effective noninvasive blood flow technique in diagnosing and following these patients. Three patients were treated successfully with medical therapy and one patient with optic nerve fenestration. The two patients with thrombosed central venous catheters had serious systemic illnesses and suffered permanent visual loss.

Adult↗
PubMed1992

Bilateral retinal hemorrhages from megaloblastic anemia: case report and review of literature.

A 33-year-old woman who was a chronic alcohol abuser and had bilateral visual loss was found to have megaloblastic anemia with thrombocytopenia. Both fundi showed retinal venular dilatation and tortuosity, superficial and deep intraretinal hemorrhages, white-centered retinal hemorrhages, and optic disc edema. Her megaloblastic anemia was caused by vitamin B12 and folate deficiencies, resulting from an inadequate diet and alcohol abuse. The retinal changes were believed to be the result of the severe anemia and thrombocytopenia. Both the megaloblastic anemia and retinal changes resolved promptly after she received vitamin B12 and folate supplements. This case shows that megaloblastic anemia should be suspected as a cause of bilateral retinal hemorrhages.

Adult↗
PubMed1991

Early-onset autosomal dominant retinitis pigmentosa with severe hyperopia.

We studied a four-generation family with early-onset autosomal dominant retinitis pigmentosa, severe hyperopia, and axial eye lengths of less than 20 mm. The affected members had decreased vision, night blindness, typical peripheral retinal pigmentary changes, and electroretinographic abnormalities characteristic of retinitis pigmentosa. This pedigree suggests there is another variant of retinitis pigmentosa associated with hyperopia besides Leber's congenital amaurosis and preserved para-arteriole retinal pigment epithelium.

Adolescent↗
PubMed1991

Effect of cataract on automated perimetry.

Humphrey visual fields (30-2 program) were performed on 24 otherwise healthy patients before and after cataract extraction to examine the effect of cataract on automated visual fields. All patients met reliability index criteria and recovered visual acuity of 20/25 or better. The effect of learning associated with repeated testing was controlled with visual fields of the fellow eye. Although a greater absolute threshold recovery occurred in the central region of the visual field after cataract extraction, the percent of threshold recovery did not vary across the visual field except for the most peripheral testing points, which demonstrated less recovery. Thus, cataracts depress an automated visual field fairly uniformly. Clinical grading of cataracts by a single experienced clinician was generally a poor predictor of visual field loss. Only the presence of posterior subcapsular plaque in the visual axis and the preoperative visual acuity correlated significantly with postoperative central threshold recovery. Pattern standard deviation remained unchanged after cataract removal, confirming it as a useful way of estimating visual loss from cataracts.

Aged↗
PubMed1991

Lamellar corneal autograft for corneal perforation.

A corneal perforation developed in the right eye of a 46-year-old man after removal of a corneal foreign body. Two attempts to seal the perforation with cyanoacrylate glue failed. The patient subsequently underwent lamellar corneal autograft, which successfully closed the perforation. To the best of our knowledge, this is the first report of repairing a corneal perforation with lamellar corneal autograft.

Corneal Injuries↗
PubMed1990

Visual prognosis in macular retinoblastomas.

Since 1979, we have treated 11 patients who had macular retinoblastomas. Two patients eventually recovered 20/20 visual acuity despite the presence of subretinal fluid in the fovea at the time of diagnosis. The diagnosis was made at 11 and 14 months of age, and follow-up periods were ten and seven years, respectively. One case was sporadic and the other was hereditary. Both patients were treated with external radiation; one patient was also treated with chemotherapy. The lesions regressed markedly after treatment. These cases demonstrate that visual prognosis in macular retinoblastomas is not uniformly poor even when a foveal detachment is present. Visual acuity may be good in some cases, which supports the merits of medical treatment rather than enucleation in selected patients.

Eye Neoplasms↗
PubMed1990

A unilateral cataract produces a relative afferent pupillary defect in the contralateral eye.

The relative afferent pupillary defect (RAPD) was measured with neutral density filters in ten patients, each of whom had a dense cataract in one eye only. In each instance, the cataract reduced visual acuity to counting fingers or worse, whereas visual acuity in the other eye was 20/25 or better. All patients with mature or nuclear cataracts had a measureable RAPD in the other eye (mean, 0.44 log unit). In each instance, after extraction of the cataract, the RAPD disappeared. Thus, a dense cataract causes an RAPD in the contralateral eye by increasing the pupillomotor effectiveness of the stimulus light and that this is the reason why even a brunescent cataract does not cause an RAPD in the same eye. In addition, two clinical cases are reported. One case records the development of a cataract in an eye with a preexisting RAPD resulting from optic neuritis; as the cataract became more opaque, the afferent defect became smaller and finally was reversed. The other case shows that a traumatic cataract can produce an RAPD in the contralateral eye. Thus, when an afferent pupillary defect is seen in an eye with a cataract, a visual pathway defect in that eye should definitely be suspected.

Adult↗