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Biomedical subjects

T Mark Johnson

Publications and source records attributed to T Mark Johnson.

5 recordsLinked to original sources
PubMed2005

Micropulse laser treatment of retinal-choroidal anastomoses in age-related macular degeneration.

BACKGROUND: Retinal-choroidal anastomoses (RCA) are a common finding in advanced cases of age-related macular degeneration. These high-flow lesions are associated with extensive subretinal exudation. This study examines the role of high-energy, short-duration (micropulse) laser pulses in effectively closing these shunts and reducing subretinal fluid. METHODS: Nineteen consecutive eyes with advanced age-related macular degeneration undergoing treatment of RCAs to reduce subretinal exudation in a referral-only retina practice were reviewed retrospectively. RCA were identified using high-speed indocyanine green angiography. RCA were closed using a high-energy, short-duration laser pulse technique. Outcome measures included visual acuity, resolution of subretinal fluid and persistence of RCA. RESULTS: Nineteen eyes with RCA associated with macular degeneration were successfully treated. Mean baseline visual acuity was 20/140 (HM to 20/50). One hundred percent of eyes had subretinal exudation and 73% had subretinal fibrosis at the time initial treatment. At mean follow-up of 11.7 (2-23) months, patients had undergone an average of 3.52 (1-12) sessions of laser treatment. Average final visual acuity was 20/146 (CF to 20/40). Fifty-three percent of eyes had complete resolution of subretinal fluid. One hundred percent had subretinal fibrosis. Forty-three percent had complete closure of RCA. No significant complications were encountered. CONCLUSION: High-energy, short-duration laser appears to be a reproducible technique to obtain closure of RCA associated with advanced macular degeneration. It appears to be effective in reducing subretinal exudation associated with these lesions. The technique is associated with stabilization of visual acuity without significant risk of complication.

Aged↗
PubMed2004

Pathogenic implications of subretinal gas migration through pits and atypical colobomas of the optic nerve.

OBJECTIVE: To describe subretinal migration of gas and silicone oil in a series of patients with congenital cavitary optic disc anomalies and to further clarify the pathogenesis of the associated maculopathy. METHODS: Medical records of 4 female patients, aged 8 to 34 years, who developed subretinal gas migration after vitreous surgery for macular detachment associated with cavitary optic disc anomalies were reviewed. A theoretical model was used to calculate the pressure differential required to induce subretinal gas migration through an optic pit. RESULTS: The 4 patients had bilateral atypical optic nerve colobomas or a unilateral large optic pit. A definite defect in the tissue overlying the disc excavation could be seen in one eye, and intraoperative drainage of subretinal fluid through the disc anomaly was possible in all cases. Subretinal migration of gas or silicone oil was seen intraoperatively in one case and first appeared between 1 and 17 days postoperatively in the remaining cases. Theoretical calculations suggest that the pressure differential required for migration of gas through a small defect in the roof of a cavitary disc lesion is within the range of expected fluctuations in cerebrospinal fluid pressure. CONCLUSIONS: These observations provide clinical confirmation of a defect in tissue overlying cavitary optic disc anomalies and imply interconnections between the vitreous cavity, subarachnoid space, and subretinal space. We theorize that intermittent pressure gradients resulting from normal variations in intracranial pressure play a critical role in the pathogenesis of retinopathy associated with cavitary disc anomalies.

Adult↗
PubMedDate not supplied

Coats' syndrome as a cause of secondary open-angle glaucoma.

A case of Coats' syndrome presenting with acute secondary open-angle glaucoma is described. A 41-year-old woman presented with eye pain and an intraocular pressure of 50 mm Hg in the right eye. Numerous hyperrefringent yellow-white crystals were seen in the anterior chamber and in a recessed anterior chamber angle. Fundus examination revealed an inferior yellow exudative retinal detachment with retinal vascular abnormalities resembling Coats' disease. Following lensectomy, vitrectomy, retinal reattachment, and endolaser photocoagulation, the intraocular pressure stabilized within normal limits. Coats' syndrome may cause increased intraocular pressure by a secondary open-angle mechanism, even in phakic eyes. Removal of the lipid crystals and treatment of the anomalous vessels may be sufficient to control the intraocular pressure.

Adult↗