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Biomedical subjects

M A Nasir

Publications and source records attributed to M A Nasir.

8 recordsLinked to original sources
PubMed1998

Clinicopathological correlation of primary and recurrent choroidal neovascularisation following surgical excision in age related macular degeneration.

AIMS/BACKGROUND: Fluorescein angiography and histopathological findings were correlated in two patients with recurrent choroidal neovascular membranes (CNVs) in an attempt to gain insight into the possible causes of recurrent CNVs and into the healing response after CNV excision. METHODS: Two patients with recurrent CNVs underwent repeat excision, and the excised tissue was studied with light and electron microscopy. RESULTS: Incomplete CNV excision probably led to the recurrences. The portion initially excised appears to have been anterior to the RPE in case 1. In both cases, recurrent CNVs contained RPE-like like cells suggesting that native RPE can repopulate the dissection bed. The tissue excised at the second operation contained areas with hyperplastic RPE and fragments of Bruch's membrane (external to the RPE basement membrane) in a matrix of fibrillar collagen and fibrocytes, suggesting that initial removal of the CNV can be followed by an abnormal anatomical arrangement of RPE and scarring of Bruch's membrane. CONCLUSIONS: Abnormal resurfacing of the dissection bed by RPE and fibroblasts may underlie, in part, the limited visual outcome often seen after surgical excision of CNVs in age related macular degeneration.

Aged↗
PubMed1997

Recombinant hirudin prevents postoperative fibrin formation after experimental cataract surgery.

PURPOSE: The authors studied the effect of a direct acting antithrombin agent, desulfatohirudin variant 1 (Revasc, Ciba-Geigy, Ltd., Basel, Switzerland), on postoperative fibrin formation after cataract surgery in rabbits. METHODS: Phacoemulsification was performed in a masked fashion on 28 eyes of 28 New Zealand white rabbits. Ten control group eyes had lactated Ringer's solution in the infusion and an intracameral injection (approximately 1.5 ml) at the end of the case. Ten group 1 eyes received hirudin 100 micrograms/ml in the infusion and intracameral injection. Eight group 2 eyes had 100 micrograms/ml hirudin in the intracameral injection only. Using slit-lamp examination, all eyes were graded for the amount of fibrin and intraocular hemorrhage in a masked fashion on postoperative day 1. RESULTS: Comparison of the mean postoperative fibrin grade (0-4) in group 1 (mean = 0.3), group 2 (mean = 0.25) and the control group (mean = 3.4) revealed a statistically significant difference between hirudin-treated and control eyes (P = 0.0002 for group 1, P = 0.0005 for group 2). No intraocular hemorrhage was noted in any group. CONCLUSIONS: Recombinant hirudin significantly decreases postoperative fibrin formation in a rabbit cataract extraction model. Intracameral injection of hirudin alone appears to be at least as effective as infusion of hirudin throughout the case. With further study, this agent has potential for use in cataract surgery on patients known to be at high risk for postoperative fibrin formation.

Animals↗
PubMed1997

Intraocular injection of recombinant hirudin to prevent experimental postoperative fibrin.

PURPOSE: To test the efficacy of a single intraocular injection of various doses of recombinant desulphatohirudin variant 1 (Revasc) in a rabbit model after lensectomy-vitrectomy surgery. METHODS: Standard fragmatome lensectomies and core vitrectomies were performed on Dutch Belted rabbits. In a masked fashion, 17 control eyes received single intraocular injections of lactated Ringer's solution, and the treated eyes, with eight eyes per treatment group, received single intraocular injections of hirudin at doses of 0.02 microgram, 2 micrograms, 10 micrograms, 50 micrograms, or 200 micrograms. RESULTS: Intraocular injections of hirudin were effective in preventing postoperative fibrin formation at doses of 2 micrograms. There was no notable intraoperative bleeding. With an injection of 2.0 micrograms hirudin there was no hemorrhage at any time after surgery; with an injection of 200 micrograms hirudin, however, there was notable bleeding. CONCLUSION: Hirudin is effective in the prevention of postoperative fibrin formation with a single intraocular injection of 2.0 micrograms after lensectomy-vitrectomy surgery in the rabbit model. There was no bleeding at the effective dose of 2.0 micrograms; at 100 times the effective dose, however, there was significant postoperative bleeding.

Animals↗
PubMed1997

Decreased choriocapillaris perfusion following surgical excision of choroidal neovascular membranes in age-related macular degeneration.

AIMS/BACKGROUND: To evaluate macular changes following surgical excision of subfoveal choroidal neovascular membranes (CNVs) in age-related macular degeneration (AMD). METHODS: The clinical records, fluorescein angiograms, and CNV histopathology of 12 patients with AMD who underwent surgical excision of subfoveal CNV were reviewed. RESULTS: New areas of decreased choriocapillaris perfusion were noted by fluorescein angiography in the previous location of the CNV in 8/12 (75%) cases. Surgically excised tissue contained retinal pigment epithelium (RPE) in 11/11 specimens and choriocapillaris in 1/11 specimen studied. CONCLUSIONS: Choriocapillaris atrophy may partly underlie the limited visual outcome following subfoveal surgery for AMD. Abnormal choriocapillaris perfusion following CNV excision may be due to pre-existing choriocapillaris atrophy, to choriocapillaris damage or removal at the time of surgery, or to RPE removal at surgery with abnormal RPE repopulation of the dissected area and subsequent choriocapillaris degeneration.

Aged↗
PubMed1996

Recombinant hirudin for prevention of experimental postoperative intraocular fibrin.

PURPOSE: To determine the efficacy of a specific antithrombin agent (recombinant desulphatohirudin variant 1 [Revasc, Ciba-Geigy, Ltd., Basel, Switzerland]) administered in the infusion fluid to prevent early postoperative fibrin formation in a rabbit lensectomy and vitrectomy model. METHODS: Standard fragmatome lensectomies and core vitrectomies were performed prospectively in a masked fashion on ten control eyes with lactated Ringer's infusion and on ten eyes treated with 10 microgram of recombinant hirudin/ml in the infusate. The amounts of fibrin and hemorrhage were graded in a masked fashion by using slit-lamp examination and indirect ophthalmoscopy on postoperative days 1 through 5 and on day 7. RESULTS: The difference in the mean grade of fibrin formed on the first postoperative day in the eyes treated with recombinant hirudin (mean, 0.9) in relation to the mean grade of fibrin in the control eyes (mean, 3.5) was statistically significant (P = .004). This difference was also significant on the second postoperative day (P = .01). None of the treated eyes developed intraoperative or postoperative hemorrhage. CONCLUSIONS: Recombinant desulphatohirudin variant 1 is an effective inhibitor of postoperative fibrin formation in a rabbit model and is not associated with an increased risk of intraoperative or postoperative bleeding at the tested dose. This drug may be a useful adjunct in vitreous surgery for both proliferative vitreoretinopathy and the complications of proliferative diabetic retinopathy.

Animals↗
PubMed1996

Cytomegalovirus retinitis associated with Hodgkin's disease.

BACKGROUND: Patients with intraocular involvement by Hodgkin's disease may present with a variety of ocular abnormalities. Intraocular infections also have been reported in these patients, including two cases of cytomegalovirus retinitis (CMV) diagnosed on postmortem examination. It often is difficult to differentiate between these conditions on clinical examination. METHODS: A patient with Hodgkin's disease presented with an atypical retinitis, vasculitis, and a serous macular detachment. Results of clinical examination, fluorescein angiography, and vitreous biopsy for culture and polymerase chain reaction (PCR) testing are described. RESULTS: The diagnosis of an atypical CMV retinitis simulating possible intraocular involvement by Hodgkin's disease was confirmed by PCR testing of undiluted vitreous. Intravenous therapy with foscarnet, guided by the results of the vitreous biopsy, resulted in resolution of the retinitis and an improvement in vision. CONCLUSION: Intraocular involvement by cytomegalovirus retinitis can simulate intraocular lymphoma in a patient with Hodgkin's disease Polymerase chain reaction testing was useful in establishing the diagnosis and guiding successful therapy in this patient.

Adult↗
PubMed1991

Multiple endocrine neoplasia type III.

The multiple endocrine neoplasia (MEN) syndromes are autosomally dominant inherited disorders in which hyperplastic or neoplastic changes occur in a wide variety of tissues. The specific syndromes are classified according to the endocrine glands affected. MEN type I consists of an aggregation of tumors of parathyroid, pancreatic, and pituitary glands. The association of medullary carcinoma of the thyroid (MCT) and pheochromocytoma is called MEN type II or type IIA, and if combined with mucosal neuromas, intestinal ganglioneuromatosis, and prominent corneal nerves, is named MEN type III or type IIB. Individuals afflicted with MEN type III are characterized by a marfanoid habitus, mucosal neuromas involving oral and ocular tissues, and a number of ophthalmologic findings including prominent corneal nerves, thickened eyelids, and subconjunctival neuromas. These features are easily recognized during the ocular exam, allowing the ophthalmologist to make an early diagnosis of this syndrome prior to the onset of life-threatening manifestations like medullary thyroid carcinoma and pheochromocytoma.

Adult↗