The digital indocyanine green videoangiography characteristics of well-defined choroidal neovascularization.

PURPOSE: To evaluate the digital indocyanine green (ICG) videoangiography characteristics of well-defined choroidal neovascularization (CNV). METHODS: The authors retrospectively reviewed all ICG angiograms performed at the New England Eye Center over a 2-year period. Included in this study were all patients with the clinical and fluorescein angiographic diagnosis of well-defined CNV according to the Macular Photocoagulation Study Group criteria. RESULTS: Of the 25 eligible patients, 18 (72%) had a well-demarcated area of ICG hyperfluorescence that was observed either both early and late (6 patients = 24%) or only late (12 patients = 48%) on the ICG angiogram. Five patients (20%) showed only poorly demarcated late hyperfluorescence on ICG angiography. Two patients (8%) had type II occult CNV associated with classic CNV as per the Macular Photocoagulation Study Group criteria. Both patients showed a late, well-demarcated area of ICG hyperfluorescence greater than the area imaged with fluorescein angiography. CONCLUSIONS: Choroidal neovascularization which is well-defined on fluorescein angiography has variable ICG appearances. When there is late leakage associated with a well-defined CNV on fluorescein angiography (type II occult CNV), ICG angiography may more completely delineate the extent of the lesion.

Holmium-YAG laser surgery on experimental vitreous membranes.

We used a pulsed holmium-YAG laser that emitted in the midinfrared (2.12 microns) to cut experimental vitreous membranes in rabbits via an intraocular fiberoptic delivery system. Thirty-five membranes were treated at distances of 0.5 to 3.8 mm from the retina. All of the membranes that were treated were transected or partially cut. In cases that were treated with the optical fiber encased in a retinal-shielding pick, membranes could be readily transected without retinal injury. Laser vitreous membrane cutting may offer the advantage of near-tractionless membrane segmentation. The combination of a moderately strong target tissue absorption and the ready availability of commercial optical fibers for transmission of 2.12-microns laser energy suggests that the holmium-YAG laser merits further investigation for this application.

Erbium-YAG laser surgery on experimental vitreous membranes.

We used a pulsed erbium-YAG laser emitting in the midinfrared region (2.94 microns) to cut experimental vitreous membranes in rabbits via an intraocular fiberoptic delivery system. Thirty-four membranes were cut at distances of 500 to 3600 microns from the retina. All 34 of the membranes treated were effectively cut. Sixteen cases had no evidence of retinal injury, including one in which the membrane was only 800 microns from the retina. Retinal injuries in the remaining cases consisted of small (less than 300 microns) retinal burns and hemorrhages. In 94% of the cases with retinal injury, the fiberoptic was within 2000 microns of the retina. We conclude that a pulsed erbium-YAG laser allows near tractionless cutting of vitreous membranes and may have potential for clinical use if further studies show it to be efficacious and safe near the retina.

Mechanism of diminished contractile response to catecholamines during acidosis.

To examine mechanisms of diminished contractile response to catecholamines during acidosis, we studied contractile properties, beta-adrenergic receptor properties, and intracellular pH of intact, cultured myocardial cells from chick embryo ventricle at pH 7.4 and 6.8. Contractile response was measured with an optical-video system. On changing the superfusing buffer from pH 7.4 to 6.8 there was a decline in contractile amplitude to 80% of control by 20 min. Fluorimetrically determined intracellular pH declined over a similar time course from 7.11 +/- 0.05 to 6.96 +/- 0.07 (P less than 0.05). After 45 min at pH 6.8 the contractile response to 1 microM isoproterenol was less than half of the response at pH 7.4. Antagonist and agonist ligand-binding properties of the beta-adrenergic receptor were determined in the intact cells under conditions identical to those for the contractility studies. With the use of the hydrophilic antagonist [3H]CGP-12177 that selectively labels cell-surface receptors, agonist competition studies demonstrated that acidosis had no significant effect on antagonist or agonist affinity but decreased beta-receptor number from 21 +/- 3 to 11 +/- 3 fmol/mg protein (P less than 0.02). It is probable that a decline in the number of beta-receptors on the cell surface contributes to contractile hyporesponsiveness to catecholamines during acidosis.