David M. Worthen

The FDA Report on Intraocular Lenses

Clinical studies of intraocular lenses (IOLs) as investigational devices have been regulated in the United States by the Food and Drug Administration (FDA) since 9 February 1978. As of August 1982, data have been collected on more than one million IOLs implanted. During the last 12 months of the study, 409 000 IOLs were implanted. Visual acuity of 20/40 or better at one year after surgery was present in 85% of over 45 000 cases reviewed. Increasing patient age, surgical problems, postoperative complications, and adverse reactions were factors that reduced the visual acuity. The current trend in the USA is for implantation of posterior chamber and anterior chamber IOLs.

Neodymium: YAG lasers. An FDA report.

Analysis of data from four neodymium:YAG laser manufacturers submitted to the Food and Drug Administration (FDA) on over 17,000 cases indicate the procedure is safe and effective for cutting opaque posterior lens capsules. A successful opening in the pupillary membrane was achieved in 98% of the cases, and vision improved in 84% of the cases. Clinically significant risks include: a rise in intraocular pressure two to four hours after treatment, damage to the intraocular lens, and rupture of the anterior hyaloid face.

Cystoid Macular Edema in Pseudophakia

Cystoid macular edema after cataract surgery, with or without intraocular lens implantation, has been reported to develop in more than 50% of patients as detected by fluorescein angiography. It is associated with reduced visual acuity in up to 8% of cases. Analysis of ongoing clinical trials at the Wilmer Institute indicates that clinically significant cystoid macular edema develops in a lower percentage of cases (2% total incidence and 0.3% persistent cystoid macular edema) if the intraocular lens implantation was uncomplicated. The factors associated with cystoid macular edema and the importance of considering clinically significant rather than just fluorescein-proven cystoid macular edema are discussed. Results of intraocular lens studies reported to the Federal Drug Administration are updated, and results of an ongoing study of prostaglandin inhibitors at the Wilmer Institute are reported.

Corneal Endothelial Damage Associated by Phacoemulsification

Twenty-one cats underwent standard Kelman phacoemulsification procedures in their right eyes. The left eyes of the same amimals underwent a planned extracapsular cataract extraction or irrigation and aspiration for 15 minutes using the Kelman phacoemulsification unit. The corneal endothelium was evaluated at various times postoperatively using a stain for endothelial cell viability and scanning electron microscopy. The results suggested that the irrigation procedure alone is deleterious to the cat endothelium as is the rubbing of nuclear material against the endothelial cells. These two procedures caused additonal damage when combined in a routine phacoemulsification procedure.

Trends in Cataract Surgery and Intraocular Lenses in the United States

Cataracts are the second leading cause of blindness in the United States. The rate of cataract surgery has greatly increased in the past several years, in part because of the extensive use of intraocular lenses for aphakic correction. It is estimated that more than 600,000 cataract operations were done in 1982. During a similar period, an estimated 496,000 intraocular lenses were implanted. Thus, more than 70% of all cataract operations in the United States involved intraocular lens implantation. Although iris fixation lenses accounted for 52% of all intraocular lenses implanted in 1978, during the six-month period from July 1982 through January 1983 57% of all implanted intraocular lenses were posterior chamber lenses and 40% were anterior chamber lenses.

ARGON LASER TRABECULOTOMY: LONG-TERM FOLLOW-UP

A five-year follow-up of argon laser trabeculectomy in a group of 28 male patients with bilateral patients with bilateral primary open-angle glaucoma showed an overall mean pressure drop of 10.3 mm Hg in treated eyes. Twenty percent of the treated eyes had a pressure less than 20 mm Hg up to two years after treatment. No specific laser parameters were associated with pressure lowering. The pressure drop appears more patient dependent than treatment dependent. A randomized clinical trial is suggested.

Interim FDA Report on Intraocular Lenses

Intraocular lenses have been regulated by the Food and Drug Administration since February 9, 1978. Data reported through August 9, 1979 reveal 177,503 lenses of four different classes have been implanted. The anterior chamber intraocular lens appears to have a higher incidence of certain postoperative complications compared with both control operations and implantation of lenses in the other three classes. The anterior chamber intraocular lens appears to be associated with a lower level of visual acuity compared with both control cases and the other three lens classes during the first six months following implantation. Some complications occurred less frequently following implantation of intraocular lenses than in control cases.

Immobilization of viral antigens on filter paper for a [125I]staphylococcal protein a immunoassay: A rapid and sensitive technique for detection of herpes simplex virus antigens and antiviral antibodies

A new technique is described for the rapid detection and quantitation of herpes simplex virus (HSV) antigens and antiviral antibodies. It involves immobilization of HSV antigens on filter paper discs and subsequent analysis by 125I-labeled staphylococcal protein A (SPA) radioimmunoassay. A specially designed 96-well filtration device is employed which serves both as an incubation chamber and as a filtration manifold. It is rapid, simple, sensitive and specific, and requires only small volumes of antiserum and few target cells. The results may be readily and objectively quantitated. This technique permits the simultaneous assay of a large number of specimens in less than 1 h. Its sensitivity is considerably greater than that of other currently used immunologic techniques, and it is amenable to automation. These characteristics suggest that this [125I]SPA immunofiltration technique may be applicable to the rapid diagnosis of viral infections.

Update of Intraocular Lenses Implanted in the United States

T he J ournal invites letters that describe unusual clinical or pathologic findings, experimental results, and new instruments or techniques. The title and the names of all authors appear in the Table of Contents and are retrievable through the Index Medicus and other standard indexing services. These brief reports must not duplicate data published or submitted for publication elsewhere. Each letter must be accompanied by a signed statement transferring copyright to The Ophthalmic Publishing Company. Letters must be typed, double-spaced, on 8½ × 11-inch bond paper with 1½-inch margins on all four sides. They should be no more than two typewritten pages in length. A maximum of two black and white figures may be used; they should be cropped to a width of 2⅔ inches (one column). Color figures cannot be used. References should be limited to five. Letters may be referred to outside editorial referees for evaluation or may be reviewed by members of the Editorial Board. All letters are published promptly after acceptance. Authors do not receive galley proofs, but if the editorial changes are extensive, the typescript is sent for approval.

Quantitative morphometry of conjunctival microcirculation in diabetes mellitus.

Abstract The minute vessels of the bulbar conjunctiva were examined by vital microscopy in diabetics and age-matched nondiabetics in order to establish a quantitative index of the vascular changes reported to accompany diabetes mellitus. Photographic enlargements were analyzed by the use of stereological techniques. Initially, microvascular density was approximated by using grid analysis to measure the total length of given-sized microvessels per unit area of conjunctival tissue ( L A ). The microscopic blood vessels ranged in diameter from 10 to about 100 μm and were separated into three general categories: total L A of all visible vessels; L A for vessels over 30 μm in diameter (primarily venules); and L A for vessels from 10 to 30 μm in diameter (primarily capillaries and postcapillaries). The patient pool was subdivided into four cohorts, each covering an age span of 15 years. In both diabetics and nondiabetics, the total L A or vascularity increased progressively with age, the primary factor being an increase in the number of venules. An important distinction, however, was that in each of the four age cohorts, diabetics had substantially fewer small vessels.