MULTIFOCAL IOLS: FUNCTIONAL PERFORMANCE TESTS SHOULD BE PERFORMED
This article was originally published in The Gray Sheet
MULTIFOCAL IOLS: FUNCTIONAL PERFORMANCE TESTS SHOULD BE PERFORMED to assess adverse effects on patients' vision, FDA says in a Feb. 16 letter to sponsors of multifocal intraocular lens investigational device exemption studies. In the letter, FDA suggests that sponsors undertake two types of clinical substudies during their trials in order to demonstrate that "multifocal IOLs do not have a significant adverse affect on the functional performance of subjects that receive these types of IOLs." FDA says it is "especially concerned" about the performance of patients with multifocal IOLs in both eyes. The letter, which was discussed at a Feb. 26 ophthalmic devices panel meeting, proposes changes to a June 1990 guidance that outlined preclinical and clinical studies for multifocal IOLs ("The Gray Sheet" June 25, 1990, p. 8). The letter recommends that sponsors test their subjects' performance ability "at the distant task of driving under environmental conditions which increase the difficulty of the task, such as driving under conditions of inclement weather, night driving, etc." According to the letter, the clinical substudy should compare the performance of three populations of patients (those with bilateral multifocal implants, those with only one multifocal implant and a control group consisting of patients with monofocal implants in one or both eyes) at "tasks which may be affected by the optical performance limitations of their multifocal IOL." Examples of such tasks include reading highway signs and detecting hazards at varying distances and under varying conditions of road lighting and glare. Another appropriate task would be "lane tracking on a winding, unlit road at night." The second test, called the Worth Four Dot Test, is being proposed as an addition to the requirements because "FDA has received information from some sponsors...that subjects are experiencing an adaptation period, or experiencing other visual disturbances that could be related to non-fusion or non-suppression of the multifocal image or of unwanted visual signals." Also, the agency notes, "sponsors and their medical monitors have indirectly indicated that monofocal/multifocal IOL subjects are not as visually satisfied as the bilateral multifocal implantees." Therefore, FDA says, "we believe that, at a minimum, sponsors should perform the Worth Four Dot Test on multifocal IOL subjects to determine whether non-fusion or non-suppression of the multifocal images is causing patient visual dissatisfaction." The letter suggests that sponsors compare two groups of 50 to 100 subjects each, one group containing patients with bilateral multifocal implants and the other containing patients with a multifocal implant in one eye and a monofocal IOL in the other. The test, FDA says, should be given in the "immediate postoperative period," and "if an abnormal or incorrect response is obtained, sponsors must determine which image (multifocal or monofocal IOL) is being suppressed or non-fused," The sponsor must continue to administer the test to determine whether the condition is transient, FDA notes, adding that sponsors should consider "adding the Worth Four Dot Test as a routine test for all study subjects." The document also outlines changes in the areas of clinical study design and data analysis. According to the letter, sponsors should "prospectively provide the number of investigators proposed and a statistical justification for the investigator/subject ratio." The agency says that sponsors should have 4 to 10 investigators per 500 cohort study. The agency also asks that sponsors use a table provided in the letter "as a format for presentation of visual acuity and refraction data...in all of your IDE clinical progress reports, and in [premarket approval] applications." Commenting on the suggested changes to the multifocal IOL guidance at the Feb. 26 panel meeting, Steven Zamba, chairman of the Health Industry Manufacturers Association's ophthalmic interest subcommittee, said that HIMA is concerned with the "timing of the issuance of this additional guideline" because of the "advanced status" of some sponsors' clinical studies. For example, Zamba noted that a multifocal IOL PMA was deemed "approvable" last year ("The Gray Sheet" Jan. 27, 1992, p. 18). The recommendation for the 3M Vision Care IOL "seemed to indicate sufficient data had been collected under the current protocols to evaluate safety and efficacy." In addition, Zamba maintained that "there is no clear consensus in the literature regarding the applicability of the suggested testing for evaluating the safety and efficacy of multifocal intraocular lenses." Zamba said that HIMA would review the proposed changes further and urged the panel to do the same. Also commenting on the changes to the guidance at the Feb. 26 meeting, IoLab spokesman John Fitzgerald cited the "significant burden" that the new requirements place on sponsors, investigators and patients involved in ongoing clinical trials. Specifically, Fitzgerald charged that with respect to the driving simulation requirement, the document contains "no clear guidance as to what test should be done" and that "there is really no concurrence among those currently doing driving simulation studies as to what is the appropriate methodology to use." Thus, "this makes it very difficult on the sponsor to determine what test [to] use in order to gain approval for their particular lens."
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