Informed consent and medical devices: the case of the contact lens

It is estimated that 1.65 million people in the United Kingdom wear contact lenses, 97% of whom do so for refractive and cosmetic reasons.¹ Contact lens wearers are at risk of sight threatening adverse events such as corneal ulceration, which may lead to scarring and visual loss. The risk of corneal ulceration is approximately 1 in 3000, 1 in 2000, and 1 in 500 patients per year for hard, soft daily wear, and soft continuous wear lenses, respectively.^2–4

Informing individuals of the risks associated with contact lens wear, is important both for the wearer and person prescribing the contact lens. For consent to be legally valid it must be informed. This means that patients need information about the nature of an intervention, possible alternatives and, specifically, its benefits and risks. There is no reason why the principle of informed consent should not apply to the prescribing of a medical device such as a contact lens. We sought to determine the degree to which contact lens wearers have been informed of the risks associated with contact lens wear.

Methods

Following permission from the respective medical school deans, students at UK medical schools were contacted through electronic mail by their respective university faculties and asked if they wore or had worn contact lenses in the past year, to follow a link to a questionnaire (fig 1) sited on the world wide web.

Figure 1.

 Questionnaire.

Results

In all, 560 replies were received (table 1); 21% of students had received some verbal information regarding the risk of corneal ulceration and 1% had received this in written form. Only 2% had been told of all of the four stated risks; 12–14% of respondents were aware of the risk of corneal ulceration associated with soft daily, continuous, and hard contact lens wear. Of those who knew of this risk 41%, 37%, and 58% underestimated the respective morbidity. Only 23% of those who think that they had been given sufficient advice knew of the risk of corneal ulceration. Thirteen per cent of students reported the development of one or more complications associated with their contact lens wear. Eight per cent of students stated that had they been aware of the risks stated in the questionnaire they would not have chosen to wear contact lenses. 87% of students would still have chosen to wear a contact lens after reading the associated risks.

Table 1.

 Survey of 560 medical students who are contact lens wearers. All results are in percentages

Provision of information versus reported complications (%)
Risk	Verbal	Written	Complications*
Ulcer	18	4	3
BV	22	4	8
Scar	21	4	4
Ptosis	4	3	1
Reported awareness of risk of corneal ulceration
SDL	Aware	Unaware
Greater	18	17
Same	41	18
Less	41	65
SCL	Aware	Unaware
Greater	23	21
Same	40	7
Less	37	72
HGP	Aware	Unaware
Greater	40	29
Same	2	0
Less	58	71
Knowledge of risk of corneal ulcer versus adequacy of advice
	All	Adequate advice	Inadequate advice
SDL	14	23	21
SCL	14	24	22
RGP	12	23	17
Percentage (%) who would wear contact lens with knowledge of risks
Yes	87
No	8

*Actual complications reported by students. Blood vessel formation on the cornea (BV). Soft disposable (SDL), soft contact lens (SCL), rigid gas permeable (RGP), or hard contact lens (HGP).

Comment

Contact lenses are worn by millions of people worldwide. Although the risk of a complication is small, it constitutes a significant public health problem when applied to a large population. Individually it is necessary to balance this risk against the benefits offered by contact lens wear. This can only be achieved with the provision of appropriate information.

Although there are limitations with this type of survey, it would appear that the majority of contact lens wearers, approximately 80% (98% for all four of the stated risks) of students surveyed, were unaware of the risks to which they were exposed.

It is important that potential contact lens wearers are fully informed to allow the best choice of refractive correction for them. Consumer comparison between the potential adverse effects of various contact lens types and wear patterns is important in this decision. This is emphasised here as 8% of those involved in the study would not have chosen to wear contact lenses had they known of the associated risks.

Although there is no legal stipulation regarding the provision of information when prescribing a contact lens, providing information and obtaining informed consent forms part of good clinical practice. Although written consent is not evidence that informed discussion has taken place, written agreements can be used to provide a basis for the process.

We would recommend that informed consent be obtained when prescribing contact lenses and that this should be done with the aid of written information. Concern over the associated risks should not deter people from the benefits of contact lens wear but they are an important consideration and consumers have a right to be informed.