Dethecting glaucomatous damage with the Friedmann analyzer compared with te Goldmann perimeter and evaluation of stereoscopic photographs of the optic disk.

We used a Friedmann visual field analyzer with a 98-hole plate to test 32 normal control eyes and to establish highly specific criteria for abnormality. When these criteria were later applied to the testing of 50 additional normal control eyes, there were no false-positive abnormalities. With these criteria, the Friedmann visual field analyzer proved to be at least as sensitive as careful manual perimetry with the Goldmann perimeter in detecting early glaucomatous visual field defects. In addition to having high sensitivity and specificity, the Friedmann visual field analyzer with the 98-hole plate is rapid and requires very little training to operate. By way of comparison, examination of stereoscopic photographs of the optic disk was also sensitive in detecting or suggesting glaucomatous damage with visual field loss, but some of the normal control optic nerves were also considered suspect. Ignoring the suspect disks in order to reduce false-positive results improved specificity but simultaneously reduced sensitivity for detecting definite visual field loss. The combination of optic disk evaluation and visual field testing (with wither the Goldmann or the Friedman instrument) better detected early cases than did either test alone, because each method picked up some early cases missed by the other.

Ophthalmodynamometry: a reappraisal.

The accuracy of ophthalmodynamometry (ODM) was retrospectively analyzed in 36 patients who had ophthalmic examinations prior to carotid arteriography. In 75% of those patients, ODM correctly predicted the presence of absence of significant stenosis (ie, 50% or greater) or occlusion of the internal carotid artery. A 30% false-negative rate and 19% false-positive rate was found in this study. The accuracy was not improved when the examiner had more experience with the test. The accuracy of ODM with staff members who regularly perform the examination was 68% as compared to the ophthalmology residents' accuracy of 76%. Causes of false-negative and positive results include subjectivity of the examination, stenosis of arteries other than the internal carotids, and development of collateral circulation as was demonstrated arteriographically in 2 of our patients.

Cryocoagulation of retinal vessels: an experimental model of intravascular coagulation.

Various amounts of cryothermy were applied to the posterior pole of rabbit eyes to determine changes in retinal tissue and vasculature. Four consecutive freezing and refreezing applications of -60 degrees was the most effective technique for achieving central retinal vessel occlusion. Electron microscopic observations of sequentially sectioned occlusion. Electron microscopic observations of sequentially sectioned occluded vessels showed that the vessels were occluded by a platelet plug distally and packed erythrocytes proximally. Fibrin formation was not found in the occluded retinal vessels but was seen within platelet plugs in choroidal vessels. Because cryocoagulation simulates the normal physiologic means of coagulation more closely than other vessel occluding techniques, cryocoagulation of the primary retinal vessels is suggested as an experimental model for intravascular coagulation.

Mechanical Excision and removal of intravitreal vessels. I. In animals.

We wished to know if excision of artificially produced intravitreal vessels would cause bleeding and if the hemorrhage could be controlled by increasing the intraocular pressure. In 17 rabbit eyes, the distal end of several intravitreal blood vessels was excised and removed by the Peyman vitrophage. No significant bleeding occurred from the vessels in 13 eyes, and in the remaining four bleeding stopped after 30 seconds or less of increased intraocular pressure. In one month of observation after surgery, there was no evidence of delayed hemorrhage. Electron microscopy of several transected intravitreal vessels revealed that vessel constriction, platelets and fibrin strands contributed to the prevention of immediate and delayed hemorrhage.

Full-thickness eye wall biopsy. I. An experimental approach to the tissue diagnosis and study of choroidal and retinal lesions.

A surgical approach to full-thickness eye wall biopsy is proposed as a method that may be applied to poorly understood diseases of the retina and choroid. An eye basket is sutured to the eye for stabilization, and two trephines mark an area to which diathermy is applied until penetration is achieved. The specimen is removed with fine forceps and scissors. A scleral homograft closes the defect. In ten rabbits, no eyes were lost and all ten retinas were intact. All biopsy specimens were suitable for histologic study.