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Researchers examine risks of contact lens substitution

Scientists have reviewed the implications of substituting soft contact lenses

lens lead
A new review paper has examined the implications of inappropriate soft contact lens substitution.

The research, which was published in Contact Lens and Anterior Eye, highlighted that soft contact lenses prescribed by eye care practitioners are sometimes substituted for alternative lenses in “the mistaken belief that there is essentially no difference between different soft lens types.”

The review examined the impact of substitution on lens properties; including surface treatment, internal wetting agents, material, total diameter, back optic zone radius, thickness, edge profile, back surface design, optical design, power, colour (tint) and ultraviolet protection.

Researchers also analysed the implications of switching a prescribed soft contact lens for an alternative in terms of contact lens usage, such as wearing modality and replacement frequency.

They found that almost all forms of soft lens substitution are associated with between one and six potential sources of patient dissatisfaction and adverse events.

“A substituted lens may have properties that result in undesirable consequences
in respect of vision, ocular health, comfort and cosmetic appearance, and may be incompatible with the lifestyle of the patient,” the authors note.

They emphasised that contact lenses are medical devices which are prescribed and fitted.

“They should never be substituted for another lens type in the absence of a new prescription further to a full finalised fitting, for the simple reason that all soft
contact lenses are not created equal,” the authors noted.

The researchers note that if a prescribed contact lens is to be substituted with an alternative, this decision should only be made by a qualified eye care practitioner.
“The practitioner can weigh up the benefits of any given instance of lens substitution against the downsides of any potential altered lens behaviour, risks of an adverse ocular response, or other sources of patient dissatisfaction,” they emphasised.