End-of-day contact lens discomfort may have a chemical cause
Contact lens solutions and hand soaps can cause what one optometrist refers to as delayed subjective dryness.
When patients complain of comfort issues with contact lens wear, practitioners will first examine the ocular surface and evaluate the fit. Once those findings are found to be normal, clinicians should consider soaps and solutions.
Delayed subjective dryness (DSD), which is almost always a chemical issue, is a common soft contact lens complication that has specific and consistent characteristics. It is generally progressive in nature and results in reduced wearing time and, eventually, contact lens failure.
Patients who are experiencing DSD often believe that it is a normal and expected consequence of contact lens wear, and so do not report it as a problem in early and moderate stages. Frequently they just give up wearing contacts because glasses are “more convenient.”
Taking the history
A single question asked by the contact lens practitioner at every progress report visit will reveal the presence of DSD: “When you wear your contact lenses, do your eyes feel dry at the end of the day?” If the answer is, “yes,” and if the soft contact lenses are stable and properly fitted, the patient may be experiencing DSD. The practitioner will be surprised at how often the answer is “yes.”
Further history taking will reveal that some patients who have DSD will begin feeling dry after only a few hours of wear, while others have no lens awareness for 12 or more hours before the onset of DSD. In any case, well-fitted lenses will be perfectly comfortable between the time they settle after insertion and the onset of DSD. This period of good comfort is an essential feature of the syndrome and distinguishes it from ocular surface, fitting or other issues.
The feeling of dryness gets worse with time until the patient wants to “rip the lenses out,” a phrase they often use. Lubricating drops are of little help. The relief they provide lasts only a few minutes. In fact, if lubricating drops provide substantial relief, the patient does not have DSD. Instead, look for signs of dry eye, or look for environmental factors. See the accompanying table for features characterizing DSD.
The patient who has DSD does not have superficial punctate keratitis (SPK) or reduced tear break-up time. Meibomian secretions can be relatively normal. The tear film is, in fact, normal by any means of testing.
DSD vs. dry eye
If your thorough exam reveals a dry eye situation, then treat it in your usual manner. If the tear film is normal and the patient admits that his or her eyes feel dry after some number of hours of contact lens wear; if the dryness gets worse with time once it begins; if it does not respond well to lubricating drops; if the patient tells you or admits when you ask that they sometimes want to rip the lenses out at the end of the day, then the problem is DSD, not dry eye.
Of course, a patient can have dry eye and also DSD, but they are two different and unrelated clinical entities.
Establishing the fit
To clarify what is meant by well-fitting soft contact lenses: if the patient blinks hard and repeatedly in up gaze and straight-ahead gaze, the lens edge never crosses the limbus at any time. This will define a stable fit. If the lens edge crosses the limbus even once, it defines an unstable fit.
An unstable fit is acceptable only if the lenses are perfectly comfortable; generally they are not. Any lens awareness with an unstable fit may be attributed to the fit and may not be caused by DSD. The differential resides with the skill and experience of the practitioner. A stable lens is generally comfortable. In the unlikely event that it is not, the discomfort will begin right after insertion and is, thus, easily differentiated from DSD.
I prefer daily disposables for patients with DSD, provided a proper prescription and fit is available. If I were to find residual DSD, I would consider an unpreserved saline rinse or change to a lens packed in buffered saline.
DSD is always a chemical issue. The diagnosis is made by history alone. I have been unable to find any consistent correlation with stains and the biomicroscope. Once the diagnosis is made you need only find and eliminate the offending chemical.
Contact lens solutions
Most of the time a patient who experiences DSD is using a multipurpose contact lens care system. It does not matter which particular solution it is. If the patient has DSD, and if you want to eliminate it, you must eliminate all multipurpose solutions.
Peroxide is the best alternative for lenses that are used for more than 1 day. As long as the chemistry is correct, and no chemical residue remains on the lens at the time of insertion, the brand of disinfecting solution is irrelevant. Clear Care/AOSept (3% hydrogen peroxide, Alcon Labs) will work for some, but not most cases of DSD, because it contains surfactants. The concomitant use of a daily cleaner such as Lobob (Lobob Labs Inc.) and an unpreserved rinse is often needed. The Purilens system (the LifeStyle Comp.), which uses no chemicals, is a good choice for lenses used for up to 1 month, for patients who do not mind the “gadget.”
In the days of chlorhexidine and thimerosal we had become accustomed to finding limbal injection and SPK in our chemically sensitive patients. This was an acute response and was difficult to miss. Newer contact lens solutions are not nearly as toxic to the cornea. Chemical sensitivity takes on a chronic, indolent character. The onset of symptoms is chronologically separate from the chemical challenge, so it is easy to miss their association.
Contamination from hands
Another common source of chemical contamination of contact lenses is the patient’s hands. Compliant patients who wash their hands thoroughly before handling contacts will often have a chemical residue on their hands, and it is especially true if antibacterial or moisturizing soaps are used. This is why patients who use daily disposables can suffer from contact lens-related DSD.
The solution: all contact lens wearers should wash their hands prior to handling their contact lenses, and they should use glycerin soap such as Neutrogena (Neutrogena Corp.) or Pears (Pears International), or a soap made for contact lens wearers such as Vista-Prep (Amcon Labs Inc.). Of course, stinging upon insertion can result from poorly rinsed hands. This, however, is an immediate response and is, therefore, unrelated to DSD, which is always delayed.
It is difficult to argue with the convenience of multipurpose solutions for soft contact lens wearers, so I generally start new patients with a multipurpose solution and an appropriate soap for hand washing. If at any follow-up visit the symptoms of DSD arise, the care system is immediately changed to peroxide or Purilens.
If the patient is compliant, and if the lenses continue to fit well, the lenses will be worn all waking hours without any lens awareness. Some patients have trouble believing that the solutions or hand soap can have such a dramatic effect on their ability to tolerate contact lenses, so they do not comply. Persuade them to comply and you will have a practice filled with happy and loyal contact lens patients.
For more information:
- Salvatore Shakir, OD, can be reached at CLDoc2020@aol.com.
- Disclosure: Dr. Shakir has no relevant financial interests.