What GPs need to know when referring patients to ophthalmologists…
DRY eye is a very common condition with the potential to severely impact the quality of life of our patients. Proactive dry eye management prior to cataract surgery can make a difference in reducing patient discomfort, vision outcomes and, I believe, overall happiness.
You would therefore expect this condition to be taken seriously, especially by ophthalmologists. But only in the last decade has dry eye been recognized and respected by the wider ophthalmic community as a major clinical problem. There are many reasons for this previous lack of respect and the increased interest in the topic.
First, and perhaps most important, was the generational mindset that dry eyes were a minor irritation with no major sequelae. Dry eye was placed in the same category of importance as hay fever and dandruff, where over-the-counter symptomatic relief was perfectly acceptable. Our lifestyle changes, with much more screen time, higher viewing expectations and people generally living longer, have driven innovation to better understand DED and develop targeted, effective treatments.
Surgeons are implanting more and more presbyopia-correcting intraocular lenses (IOLs), and this trend appears to be increasing. These types of IOLs allow a patient to see at multiple distances without the need for glasses. Personally, over 80% of my cataract surgeries involve the implantation of an IOL to correct presbyopia. It’s obvious why this technology is popular, but it may be less obvious why dry eye affects vision more with these IOLs than with a standard monofocal IOL.
Most presbyopia correction IOLs bend light to obtain multiple focal points, meaning a close target for reading may only receive 25% of the available light. The quality of vision is optimal when the cornea is smooth and allows focused rays of light to pass through. Any scattering or reflection of light from a dry, irregular surface can further reduce the focused light reaching the retina and degrade image quality more than would be the case with a monofocal implant, where light is not split between targets . Dry eye is considered to be an extremely important factor in obtaining accurate measurements to plan surgeries and prepare the patient for success.
Unfortunately, we have found that dry eye is a complex condition that is not usually due to poor tear production, inflammation, or rapid tear evaporation alone. Often the clinical signs do not match the severity of the symptoms. This type of multifactorial disease results in a spectrum of dry eye patients, from patients with more pronounced evaporative changes due to meibomian gland dysfunction to autoimmune or inflammatory decreased tear production. That may seem overwhelming. Specialty dry eye clinics with modern methods to assess the type of dry eye and interventions to treat the underlying cause exist and are excellent for the more difficult cases.
When patients are referred to me (and other ophthalmologists) to consider cataract surgery, I examine their eyes with a slit lamp microscope and take measurements on their eyes to calculate what type of IOL will best suit their eyes. The most important of these measurements is keratometry, or corneal curvature. We perform basically the same surgery for every cataract surgery, but the strength of the IOL that we implant varies depending on the length and shape of the eye. The final visual result is highly dependent on getting accurate measurements.
We measure the shape of the cornea by looking at the light reflections of the liquid and variable tear film. Any dryness, variable oiliness or deposits will affect the quality of the measurements, can lead to an inaccurate IOL calculation and ultimately a suboptimal visual result. If a patient comes to me and I cannot get consistent keratometry readings, I will manage their tear film and have the patient come back for repeat measurements, usually two weeks later. This is quite a delay for some patients, so hopefully the advice below should help reduce the number of people who need repeat testing.
Although I have said that there is a spectrum of overlapping causes of dry eye, most involve meibomian gland dysfunction and are termed “evaporative” or “mixed.” Basically what this means is that the lipid layer that the meibomian glands secrete isn’t working well, becoming clogged and instead of their contents having a nice olive oil consistency, they become more buttery. This leads to an inferior lipid layer of the tear film and eventually to a faster evaporation of the aqueous layer than in a healthy ecosystem.
When primary care physicians refer a patient with dry eye symptoms for cataract surgery, both the patient and the eye care professional will appreciate an attempt to optimize the ocular surface.
Symptoms include feeling gritty, fluctuating vision, and watery eyes, especially in cold or windy environments. Due to a high likelihood of underlying factors, including meibomian gland dysfunction, I would personally treat these patients with a combination of hot lid massage and lubricating eye drops with Systane® COMPLETE* lubricating eye drops, which contain a lipid component. As the heat applied should be around 40°C to treat thickened meibum for patients with Meibomian gland dysfunction, it was found that hot Lid massages are best performed with a compress before massaging the lower lid firmly up and the upper lid firmly down. This should be done daily.
Systane® COMPLETE* lubricating eye drops are my choice here as they help to stabilize and support the quality of the lipid layer of the tear film while the hot compresses work on the meibomian secretion quality. I ask patients to apply one drop four times a day until seen at the clinic.
When patients are referred for cataract surgery but have no serious dry eye symptoms, I would still prefer to see the ocular surface optimized. For these patients, I prefer to use Systane® HYDRATION* lubricating eye drops four times a day, as there is evidence that using lubricating eye drops in the weeks leading up to surgery and again postoperatively, in my experience, results in happier patients with better vision and less discomfort . This is exactly what I wish for all my cataract patients.
dr Ben LaHood MBChB(Dist) PGDipOph(Dist) FRANZCO is a Laser Eye Surgeon and Refractive Cataract Surgeon.
*Systane Lubricating Eye Drops are indicated for the relief of dry eye symptoms
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