Identifying and addressing dry eye disease is one of the most important steps before anterior segment surgery. DR AVENELL CHEW lays out his protocol and the lubricants he uses to pave the way for a predictable outcome.
As an adopter of sophisticated refractive laser techniques and intraocular lenses (IOLs), Western Australian ophthalmologist Dr Avenell Chew is constantly on the lookout for any factors that may influence the final refractive outcome.
“I’m of the opinion that if you’re going to have surgery in the eye, especially for cataract, that it should be a one-time thing and treated as a single opportunity to obtain the vision patients are seeking,” says Dr Chew, who practises at WA Laser Eye Centre alongside managing director and principal surgeon Associate Professor Robert Paul.
“The expectations of patients following laser refractive procedures is high and reasonably so given that they usually already have excellent best corrected acuities. The key determinants in their satisfaction with the surgery are the refractive outcome and their experience of any pain or discomfort peri-operatively.”
Armed with fellowship training in cornea and external eye diseases (Birmingham & Midland Eye Centre, UK), Dr Chew is well acquainted with dry eye disease (DED) and its ability to determine cataract and refractive surgery outcomes. That’s why preservative-free artificial tears, such as Viscotears (active ingredient carbomer [polyacrylic acid]) from Bausch + Lomb, have been a key tool for optimising his patients’ ocular surface in the weeks leading up to surgery.
For instance, precise topography, tonometry and biometric measurements are prerequisites for cataract surgical planning, and the eventual post-operative visual performance. They require – as the first refractive component of the eye – an intact, healthy pre-corneal tear film.
However, suboptimal tearfilm quality is a common issue. Gupta et al., in a prospective case series of 120 cataract patients in the US, reported 80% had at least one abnormal tear film measurement parameter.1
“DED is also especially significant among people seeking laser refractive surgery, many of whom have been wearing contact lenses already because they don’t want to wear glasses,” Dr Chew says.
“And by virtue of wearing contact lenses, that tends to disturb the tear film and chronic contact lens wear can impair corneal sensation too. Pre-operatively it’s a priority for me to address any DED because the better you treat it at this stage, the fewer problems you’re going to face down the line. Ultimately your outcomes are only as good as your measurements.”
In the case of cataract surgery, Chew says an unstable tearfilm can result in significant changes to the degree of astigmatism measured pre-operatively; not only the amplitude of the astigmatism, but even the axis can change.
“If you’re implanting a lens on completely the wrong axis, then patients can potentially end worse off than pre-operatively,” he adds.
For refractive patients, DED can create variability during the pre-operative subjective refraction, creating delays and potential uncertainty leading into the procedure. “If I’ve identified significant DED pre-operatively, I’m asking patients to optimise their tearfilm with something like Viscotears, as well as additional agents depending on the aetiology of their DED, for at least four to six weeks before their measurements are taken,” he says.
“I’m very open with patients that how religious they are with the treatment will determine the accuracy of their result.”
If he’s prescribing artificial tears, Dr Chew makes a point to recommend Viscotears Gel PF. The preservative-free nature of the drop avoids any potential for toxicity prior to the surgery, given the frequency of their use. To reinforce this, Jee et al., investigated the effects of preservatives on DED after cataract surgery by randomising 80 patients to receive either post-operative preservative-free eye drops, or drops containing preservatives. Two months after surgery, those receiving preservative-free drops had better tear break up times, goblet cell counts, Schirmer I test, corneal fluorescein staining and Ocular Surface Disease Index questionnaire scores.2
For Dr Chew, Viscotears is an eye drop he’s used extensively, particularly during his fellowship in the UK. This is due to positive experiences among his patients, good therapeutic effects, and the fact it’s manufactured by a well-established company.
While lubricants play a key role in the lead up to surgery, they play an equally important part thereafter. All of Dr Chew’s refractive patients are prescribed the lubricant for several weeks post-surgery.
“The act of corneal refractive surgery results in injury to the corneal nerves and that reduces the reflex tear production of the eye. That means everyone’s going to have reduced tear production post-operatively, and some dry eye, so it’s imperative to prescribe a lubricant post-operatively,” he says.
“This is usually for four to six weeks, but even beyond that it can take three to six months. Studies show that for the vast majority of people, corneal sensitivity returns to preoperative levels by about six months.”
NOTE: References available upon request.
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