Lens substitution is a well-documented action by patients whereby a patient is prescribed one brand of contact lens but decides to buy and wear a different (usually cheaper) brand. When substituting a prescribed contact lens with a different contact lens (usually from an online source), the patient is foregoing the initial fit assessment from an eye care professional (ECP) for that substituted contact lens and cannot therefore know if the fit of the substituted lens is acceptable or not.

The wearer may assume that a comfortable lens is a well-fitting one, but a 2015 study has previously found little to no correlation between comfort and contact lens fit.1 A 2001 study demonstrated that even a borderline poorly fitting soft contact lens has an adverse effect on ocular integrity, specifically that corneal staining increases with increasing deviation from the ideal contact lens fit.2 

While contact lens substitution is not without its problems, at least the patients who choose to substitute have had some contact with an ECP in the initial fitting of their original prescribed contact lens. As such, these patients will have been educated as regards contact lens care and what to do in the case of any adverse reaction. They should also be able to recognise an adverse reaction.

There is unfortunately a body of contact lens wearers who are now self-fitting. That is to say that they are fitting themselves with their first ever pair of contact lenses without any input from an ECP. The risks for these wearers are far greater than for those patients who practice lens substitution.



In 2020, Spanish researchers published a study that aimed to investigate the ‘characteristics, behaviours, and awareness of contact lens wearers purchasing lenses over the internet’.3 In order to carry out this research; from November 2018 to May 2019, they placed a voluntary, anonymous survey on the contact lens retail website lentesdecontacto365.es. 

One of the questions on the survey was about ‘who guided the initial adaptation (optometrist, ophthalmologist or the wearer himself)’. Of the 1,264 respondents to the survey, 30.6% (387 people) reported that their initial fit was performed by themselves. The authors of the study conclude: ‘Despite being a medical device, the lack of regulation regarding their sale to the final customer and their easy availability over the internet could be trivialising contact lens use.’ 

The dates of the survey are important as this was prior to any Covid-19 restrictions being in place anywhere in the world and so it was not a lack of access to suitably qualified ECPs that necessarily drove these wearers to self-fit.

In 2021, a study from Saudi Arabia was published in which the researchers investigated adolescents’ attitudes to contact lenses.4 There is just a single sentence in the study that indicates self-fitting: ‘159 participants used contact lenses and most obtained them without proper professional consultation.’ 

Contact lenses can be sold in Saudi Arabia without a prescription. A previous (2014) study of contact lens wear among women in Saudi Arabia found that 567 women (38.7% of respondents to a survey) had self-fitted but it is not clear how many of those women were only wearing decorative contact lenses and how many may have been wearing corrective lenses.5

In another study also published in 2021, 442 contact lens wearers in Sudan who were attending contact lens clinics were surveyed about their lens procurement and usage.6 One-hundred-and-thirty-seven (31%) wearers when asked who prescribed their contact lenses, said that they were self-prescribed. 

Three wearers chose their lenses based on a recommendation from family or friends. Self-fitting was found to be a risk factor for wearers swimming while wearing lenses, but it was not found to be a statistically significant risk factor in other non-compliant behaviours. However, the subjects in this study were all attending contact lens clinics and were therefore presumably being given advice as regards to contact lens care.

At an educational event held by the Association of Optometrists Ireland (AOI) in November 2022, those attending were asked about their experience of patients who had self-fitted. A multiple choice question was posed via a mobile phone application and responses were anonymous. 

Forty-five respondents (52% of all respondents) reported that they had encountered at least one patient who had self-fitted contact lenses. In some cases, would-be contact lens wearers had attended an optical practice because they were having difficulty applying and/or removing their self-fitted contact lenses and they wanted help. 

In March 2023, a sample of 40 university students attending Technological University Dublin who wore contact lenses were asked in person who had fitted them initially with contact lenses and one wearer reported fitting themselves.

In Spain, Saudi Arabia and Ireland, access to ECPs is good and in the Sudanese study the patients surveyed were those attending contact lens clinics. Therefore, it is likely that most patients choosing to self-fit contact lenses are not doing so because of any difficulty in accessing an ECP, but because of the easy availability of contact lenses without a prescription.


Mary’s story

When Mary was 16 years old she wanted to get contact lenses. Despite being highly myopic and attending an optometrist regularly, she had no idea that contact lenses were a medical device that should be fitted by a qualified ECP. On the advice of her mother’s friend, she ordered daysoft contact lenses based on her spectacle prescription. Her spectacle prescription was:

R: -7.50/-0.75x180, L: -7.50/-1.25x180

The contact lens powers that Mary ordered were:

R: -0.75, L: -1.25

With her friend’s help and using a video she found online, Mary managed to apply both lenses. Once the lenses were in situ, Mary realised she could not see very well so she panicked and tried to remove the lenses. It took her over an hour to remove both lenses and she was so upset by the whole experience that she threw the lenses away. 

At a later date, when she was having an eye examination with her optometrist, she mentioned her experience with the contact lenses. The horrified optometrist berated Mary and told her that people have gone blind attempting what Mary had done. The optometrist did, however, subsequently fit Mary properly with contact lenses.


Lynsey’s story

At age 19, Lynsey decided she would like to try contact lenses. Unlike Mary, Lynsey knew that contact lenses should be fitted by an optometrist but she thought it would be easier to self-fit. Her spectacle prescription was -3.00 in both eyes and so this was the power she ordered in contact lenses. 

She ordered everclear lenses (the own-brand lenses of an online contact lens retailer) as they were the cheapest and they had good reviews online. When she attended our clinic, she had been wearing these lenses without any problems for three years. She had undergone eye examinations in those three years but had never mentioned to her optometrist that she was now wearing contact lenses.


Louise’s story

Louise is a qualified optometrist. She has never had to wear a distance correction. In her early 40s when she became presbyopic, she started to occasionally wear multifocal contact lenses. She has never had the fit of the lenses assessed and she chooses the prescription based on roughly what she thinks her prescription is. 

She assumes that if the lenses are comfortable then the fit is probably okay and she considers that she does not wear them for long enough periods for any significant problems to develop. She works with multiple optometry colleagues and therefore it would not be difficult for her to have a colleague assess the fit of the lenses in her eyes, but she has never asked any of them to do this.


David’s story

David was wearing single vision distance spectacles. At age 48, he was presbyopic and struggling with near vision. At an online work meeting a colleague mentioned that he had fit himself with multifocal contact lenses that he wore on an extended wear basis. Other people on the online meeting were horrified and felt that this man’s actions were foolish, but David thought this was a great idea. 

Based on his distance spectacle prescription, David ordered himself multifocal contact lenses online. He randomly chose a reading addition. He attended an ECP because he was struggling with lens application and wanted help. The practitioner persuaded David to have lenses fitted properly.

The above case studies demonstrate that self-fitters may be any age, have any prescription and may be very well educated as regards eye care. It would be incorrect to make any assumptions as to which patients are more or less likely to self-fit.


Why do patients self-fit?

There may be many reasons why people chose to self-fit contact lenses. Ignorance is one possibility. In the case of Mary, she genuinely had no idea that contact lenses were medical devices. If a young person sees their peers wearing self-fitted plano decorative lenses or indeed if they have self-fitted their own decorative lenses, then it is not a huge leap to move to self-fitting corrective lenses. 

The more ‘successful’ self-fitters there are, the more others will be encouraged to self-fit. For some, the reason may be financial. Clearly there is a cost saving to be made by self-fitting and thereby avoiding paying professional fitting fees. 

Patients struggling financially may also be more inclined to overwear their lenses (eg wearing a daily lens for several weeks) thus increasing the likelihood of complications. Convenience is also likely to be a factor. A patient can self-fit at a time of their choosing; they do not have to make or attend any appointments.



The General Optical Council standards of practice for optometrists do not refer to self-fitting or self-prescribing and so it could be argued that ECPs who fit themselves with lenses are not necessarily doing anything wrong. The General Medical Council, however, is explicit in its advice to doctors that they should avoid self-prescribing where possible and if they are obliged to do so, they should tell their own general practitioner what they have prescribed and they should document carefully why they decided to self-prescribe.

It would seem sensible for an ECP to at least ask a fellow professional to assess the fit of a contact lens because the only metrics by which a self-fitter can assess their own lens are comfort and vision and research has already shown that comfort is a poor indicator of fit.1

Patients who self-fit do not have the benefit of initial education from an ECP in areas such as care of contact lenses and recognising and addressing adverse effects, nor do they benefit from ongoing contact with an ECP at aftercare appointments. A 2014 review of contact lens complications from unregulated suppliers found 23 articles representing 70 individual cases.7 

The majority of patients had self-fitted plano decorative lenses. Of the 70 cases, 43 patients developed microbial keratitis and 31 of those patients had permanent visual loss. The authors of the review conclude that the fact that most patients had had no education in contact lens hygiene contributed to their complications.


How can we prevent patients from self-fitting?

The prevention of the self-fitting of plano decorative lenses requires a public health campaign aimed at the general public. For those patients who might chose to self-fit corrective lenses, ECPs are in a unique position to be able to educate those patients directly. From the time that a child is dispensed their first pair of spectacles, contact lens wear could be a part of the conversation. 

Simple advice such as ‘..and when she is older she may want to try contact lenses and we can fit her then’, lets both the child and parent know that contact lenses should be fitted by a qualified practitioner. This can also start a conversation around what is a suitable age at which to be fitted with lenses and what is involved in contact lens wear.

For established spectacle wearers we should ask at every appointment if they are wearing contact lenses or are considering contact lenses. The case studies above show that it is incorrect to assume that a patient is not wearing contact lenses just because they were not fitted by their regular ECP. 

If a patient has self-fitted and admit their actions during the course of an eye examination for spectacles, then this creates an opportunity to encourage the patient to have contact lenses fitted properly. A self-fitted contact lens may be a badly fitting one. If it is badly fitting, it is more likely to be too steep rather than too flat as a flat fitting lens may be quite uncomfortable and therefore may not ultimately be worn. 

A steep fitting lens can result in complications. A patient who has self-fitted will have had little or no education on contact lens care and complications and may not therefore, recognise a complication if one arises. It is our duty as ECPs to try to prevent patients from self-fitting and the only way in which we can do that is by patient education. 

  • Claire McDonnell is an optometrist and lecturer at Technological University Dublin. She is also a member of BUCCLE (British and Irish University and College Contact Lens Educators). Her research area is specialist contact lenses. She has presented in the UK, Ireland and Europe on contact lenses and optometric education.
  • The author would like to acknowledge research carried out by Grace Campion, Barry Nulty and Liam Schokman which contributed to this article.


Disclosure

The author has no financial interest in any of the products or companies stated and has no conflicts of interest to declare.


References

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  2. Young G, Coleman S. Poorly fitting soft lenses affect ocular integrity. CLAO J. 2001 Apr;27(2):68-74. PMID: 11352451.
  3. Mingo-Botín D, Zamora J, Arnalich-Montiel F, Muñoz-Negrete FJ. Characteristics, Behaviors, and Awareness of Contact Lens Wearers Purchasing Lenses Over the Internet. Eye Contact Lens. 2020 Jul;46(4):208-213.
  4. Al Saqr AM, Al-Zahrani HA, Alghamdi SK. Adolescents’ Usage and Attitude Toward Contact Lenses: A Descriptive Study In Saudi Arabia. Niger J Clin Pract. 2021 Sep;24(9):1350-1359.
  5. Abahussin M, AlAnazi M, Ogbuehi KC, Osuagwu UL. Prevalence, use and sale of contact lenses in Saudi Arabia: survey on university women and non-ophthalmic stores. Cont Lens Anterior Eye. 2014 Jun;37(3):185-90.
  6. Gammoh Y, Abdu M. Contact lens procurement and usage habits among adults in Sudan. PLoS One. 2021 May 19;16(5):e0251987.
  7. Young G, Young AG, Lakkis C. Review of complications associated with contact lenses from unregulated sources of supply. Eye Contact Lens. 2014 Jan;40(1):58-64.