Despite the continual advances in contact lens materials and cleaning solutions we have enjoyed in recent years, the Food and Drug Administration guidelines for lens/solution compatibility testing have not changed in 20 years. The current guidelines cover the following:

(1) lens compatibility—does the solution alter the lens parameters?
(2) cleaning effectiveness, determined through the use of Critical Micelle Concentration
(3) microbial testing, with the use of predetermined microbes
(4) toxicology testing, to determine cytotoxicity, systemic toxicity and ocular irritation
(5) clinical testing, with a minimum of 60 subjects over one month

These seemingly well-designed guidelines failed to keep the public entirely safe. A number of factors raised questions about whether the old guidelines were still applicable for today’s lenses, including the outbreaks of Fusarium (in 2006) and Acanthamoeba (in 2007).

Beginning in 2008, the FDA met with a number of leaders in the field and initiated a series of research projects to determine what flaws existed in the current system. The results were published in the November 2012 Eye & Contact Lens.
The FDA met on May 13, 2014 to establish new guidelines for future solution testing. So, what changes will be made?

Overhauling the Program
In this column and several to follow, we’ll look at each of the five FDA testing categories and discuss what is being updated, beginning this month with lens compatibility.

Lens materials were far less complex in the past than they are today. The four testing groups (Table 1) were based on water content and ionicity of the lens. This grouping was devised to make solution testing more affordable; instead of testing every solution with every lens, just one lens from each group had to be tested with the proposed solution. However, new silicone materials have varying surface properties and different patterns of uptake and release of chemicals than hydrogel lenses.

Table 1. Conventional Hydrophilic Material Group Description
Hydrophilic Group	Water Specification	Ionicity
I	Low Water Content (<50%)	Nonionic
II	High Water Content (>50%)	Nonionic
III	Low Water Content (<50%)	Ionic
IV	High Water Content (>50%)	Ionic

As such, a new series of testing groups was devised to address silicone hydrogels. The new standards will account for the variation in silicone hydrogel lens properties and will add five new categories to the existing material group descriptions (Table 2). Dimensional stability and tolerance of silicone hydrogel lenses will be added to the testing.

Table 2. Silicone Hydrophilic Material Group Description
​ Silicone Hydrophilic Group	​ Water Specification	​ Ionicity	​ Surface Properties
V-A	No Water Specification	Ionic
V-B	High Water Content (>50%)	Nonionic
V-C	Low Water Content (<50%)	Nonionic	Hydrophilic Monomer Only
V-Cm	Low Water Content (<50%)	Nonionic	Surface Treated (ST)
V-Cr	Low Water Content (<50%)	Nonionic	Non-ST, Semi-interpenetrating Network

The adsorption and release of preservative is another problem addressed by the new guidelines, as it has demonstrated toxicity to the epithelium. In addition, by removing available biocide from the solution, microbes have been allowed to grow in the depleted solution. The new guidelines will ensure representative lenses do not decrease the concentration of preservatives below a specified range.

There will be further discussion about testing under noncompliant situations and ways to include information about lens/solution incompatibility on the product label.

The new FDA solution testing guidelines are a giant step forward in ensuring the safety of our patients. Stay tuned for further discussion on solution testing and any changes you and your patients will see in the future.