Biomedical subjects
K C Greenidge
Publications and source records attributed to K C Greenidge.
Glaucoma in the black population: a problem of blindness.
Glaucoma is the leading cause of blindness in blacks. Black patients usually present to the ophthalmologist with more extensive optic nerve damage as compared with whites, and the disease process follows a malignant course even after intervention is initiated. Consequent to a greater amount of iris pigmentation, blacks require medications in higher concentrations to receive significant lowering of intraocular pressure. Patients with darker, thicker irides are more prone to have subacute angle-closure glaucoma, which requires gonioscopy and the recognition of subtle details that may be difficult to interpret. If medical therapy fails, the results of noninvasive surgical intervention, such as argon laser trabeculoplasty, and traditional surgical intervention, such as trabeculectomy, have a much lower success rate in the black population when compared with studies of the general population.It is essential that the primary physician be aware of the early signs and risk factors for glaucoma, which are herein outlined in detail. Only through early recognition, proper referral, and aggressive treatment can the incidence of blindness secondary to glaucoma be decreased.
Factors associated with retinal-vein occlusion in Hispanics.
Sixty-eight foreign-born Hispanic patients with angiography-proven retinal-vein occlusion (RVO) and 50 age-, sex-, and race-matched controls were evaluated for systemic disease. Thirty of the RVO patients had central retinal-vein occlusion, and 38 had branch retinal-vein occlusion. Hypertension, the most commonly associated factor, was present in 66.2% of the RVO patients in contrast to 18% of the controls (P less than .001). Other factors which were more common in the RVO population included open-angle glaucoma (19.1% vs 8%), diabetes mellitus (16.2% vs 12%), and atherosclerotic heart disease (14.7% vs 10%); these, however, were not statistically significant (P greater than .05). Hyperlipidemia was present in 12% of the controls and 10.3% of the RVO group (P greater than .50). This is in direct contrast to reports of nonHispanic populations where hyperlipidemia has been reported to be present in up to 60% of RVO patients.
Neodymium:YAG laser iridectomy and acute cataract formation in the rabbit.
The Q-switched Neodymium:YAG (Nd:YAG) laser in the single pulse mode was used to perform iridectomies in pigmented and albino rabbits. Seventy-one iridectomies were attempted. Seventy-six percent (54/71) of these were patent at the time of enucleation. Iridectomy closure was not noted during the 24-day study period. Lenticular damage was not detected in any case. Patency rates in pigmented (70%) and albino (78%) irides were similar. Energy levels of 6 mJ or greater resulted in a higher rate of patency. Settings below 6 mJ were associated with more significant bleeding and had a low rate of success. The histology of acute Q-switched Nd:YAG laser iridectomy is characterized by fragmentation of the stroma and wide dispersion of the pigment epithelium. Minimal healing occurs with retention of normal iris architecture without atrophy or fibrosis. Results indicate that this procedure can be performed with minimal operative complications and without a tendency for closure.
Factors affecting the results of argon laser trabeculoplasty in open-angle glaucoma.
Argon laser trabeculoplasty (ALT) was performed in 232 eyes of 180 patients affected by uncontrolled primary open-angle glaucoma (POAG), exfoliation syndrome glaucoma (ESG) or pigment dispersion syndrome glaucoma (PDSG). Mean follow-up was 9 months (3-22). Mean IOP change was -21.6% (+/- 19) from the initial value. The effect of IOP was larger in patients with ESG, PDSG, and in POAG cases with more pigmented trabecular meshwork. No relationship was found between IOP changes and age or refraction of patients; the association with iridoplasty did not influence final results. An Octopus computerized perimeter was used for pre and post-treatment visual field tests. In 113 eyes Octopus exams met the requirements for quantitative analysis. In this group 17% of visual field improved, 64% remained stable and 19% worsened. A good functional response was more frequent among the eyes with less advanced disease.
Short- and long-term effects of postoperative corticosteroids on trabeculectomy.
All patients with primary open-angle or primary angle-closure glaucoma requiring trabeculectomy between January 1982 and January 1983 were entered into a randomized prospective study to evaluate the effect of postoperative corticosteroids. Twenty-three eyes in Group 1 received a cycloplegic and topical antibiotic. Twenty-nine eyes in Group 2 received the same treatment, with the addition of topical 1% prednisolone acetate. Twenty-three eyes in Group 3 received the same treatment as Group 2, with the addition of systemic prednisone. Success rate was significantly improved with the use of topical corticosteroids. Systemic steroids did not prove to be of any added benefit over topical use alone.
Change in appearance of the optic disc associated with lowering of intraocular pressure.
This report provides additional documentation that the appearance of the optic disc may improve after intraocular pressure is lowered in patients with glaucoma. Photographic records of one of the authors (GLS) were reviewed retrospectively. Seven previously unreported cases showing apparent improvement of the optic disc were found, and the patients' charts were reviewed. In two cases the improvement was transient, and in five it was lasting. Patients with evidence of disc improvement had an age range of 5 to 55 years. In one case, the scleral ring decreased in size following the lowering of intraocular pressure. In the other cases, the disc appeared to "fill in" without change in the size of the scleral ring. When improvement is short-lived, it presumably represents edema. When of longer duration, it may be a response to anterior repositioning of a posteriorly displaced lamina cribrosa, a decrease in diameter of the scleral ring, hypertrophy and/or proliferation of glial cells, or return towards normal of axonal metabolism. Because apparent improvement in the appearance of the optic disc can be subtle, it is usually not sought and is probably often unrecognized. Its true incidence is still unknown but appears to be underestimated.