Module 4: Preoperative Ocular Surface Preparation

So much attention is given to femtosecond lasers, premium IOLs and postoperative treatment regimens when discussing refractive cataract surgery that the importance of the ocular surface is often overlooked. Indeed, what surgeons can achieve with these tools is exciting, but here, Elizabeth Yeu, MD, reminds surgeons that preparing the ocular surface is the first — and most critical — step toward success.

Q. How important is the ocular surface in refractive cataract surgery? How can its condition affect postoperative visual outcomes?

Elizabeth Yeu, MD: Preoperative ocular surface preparation is driven by patients’ demands for good visual outcomes. Patients are increasingly aware that new options are available that have provided the quality of vision unparalleled to what cataract surgery used to represent — basic cataract removal. No matter how surgeons try to mitigate expectations, surgeons must do what is necessary to deliver patient satisfaction.

Premium cataract surgery is truly a perioperative experience. To deliver ultimate patient satisfaction, surgeons must be committed to excellence during the patient selection and preoperative period through to treatment, as a pristine ocular surface is paramount to achieving good outcomes. Trattler and colleagues have demonstrated the importance of preoperatively addressing the ocular surface.¹ Using fluorescein eye stain testing, nearly 77% of patients with cataracts showed some level of corneal staining, of which 50% showed central corneal staining. This demonstrates how many patients have ocular surface issues that will only compromise diagnostics if not properly treated. Even patients with mild dry eye are at risk for suboptimal outcomes, as cataract surgery itself, coupled with postoperative medications, can worsen dry eye.² In my own experience, greater dry eye disease can lead to more complaints of visual fluctuation, irritation, redness and foreign body sensation.

The bottom line is that the latest refractive cataract tools and techniques will only go so far in providing good outcomes. Without a pristine, well-maintained ocular surface, patients simply will not see well postoperatively, regardless of whether the surgeon meets his or her refractive target. Therefore, it is crucial that surgeons add ocular surface preparation to their lineup of preoperative steps.

Q. Why are many ophthalmologists not taking ocular surface issues into account as often as they should?

Yeu: First, it is important to note that patients with cataracts are knowledgeable, savvy and have higher visual expectations after cataract surgery than in the past. Yet, despite the growing wealth of advanced technologies that surgeons can offer patients, these technologically advanced procedures only represent the minority of cataract surgeries being performed today. As evidenced by 2016 Market Scope data , the penetrance of toric IOLs is 7% to 8%, while presbyopia-correcting IOLs is 5% to 6%.³ A femtosecond laser is only used in approximately 10% of all cataract surgeries.

Of the cataract surgeons using premium IOLs, only a fraction of them have fully recognized the need to address the ocular surface to optimize outcomes, and even more may still be naïve to the link between a quality ocular surface and quality of postoperative visual acuity. Cracking the code of dry eye disease is, at times, not the easiest task and, until recently, good diagnostics and therapies that support physicians’ management of ocular surface disease have been scarce. In addition, ocular surface disease treatment is not easy to incorporate into the high-volume cataract surgeon’s workflow because of the added chair time with patients, so many surgeons who have premium IOLs in their practices simply do not offer them to patients with significant ocular surface disease.

Ultimately, however, it is in surgeons’ best interest to better understand how to take care of the ocular surface, and my hope is that more surgeons will take advantage of better diagnostic tools and greater therapeutic advances available now or in the near future, thus shifting the ocular surface health trend in a positive direction.

Q. What are some lid and non-lid causes of dry eye that can affect ocular surface health?

Yeu: Although it may not be the primary cause of ocular surface issues, meibomian gland dysfunction (MGD) contributes to approximately 80% of ocular surface disease and is the leading cause of dry eye.⁴ Meibomian gland congestion builds over time, especially as blink rates decrease due to tablet and computer use, causing an egress of meibum. Congestion then leads to pressure atrophy, truncation of glands temporally and nasally and, eventually, to inflammation. Finally, tear film instability results as the meibomian glands can no longer secrete enough oils onto the ocular surface.

Anterior blepharitis is another lid disease surgeons should not overlook because it can lead to marginal keratitis, blepharokeratitis and corneal issues such as inflammation and scarring in more severe cases. Left untreated, anterior blepharitis can put patients at high risk for infection after cataract surgery.

Non-lid causes of dry eye disease and ocular surface issues vary widely from patient to patient and can include peri- or postmenopause, prolonged computer use, contact lens overuse and poor diet. In addition, systemic antihistamines, typically taken during allergy season, are known to worsen dry eye disease by decreasing aqueous production and tear film breakup time (TBUT) by more than 30%.

Ocular surface disease can also result from mechanical issues such as conjunctival chalasis, thyroid disease, anterior basement membrane dystrophy and Salzmann nodular degeneration.

Q. What steps do you suggest refractive cataract surgeons take to diagnose dry eye and ocular surface disease?

Yeu: Diagnosis of ocular surface disease depends on individual practice setup, but to ensure that all ocular surface diseases are detected — whether in new or existing patients — surgeons must first establish a standardized protocol and incorporate objective diagnostics to evaluate patients for dry eye disease, beyond just a slit lamp examination. For example, my protocol is as follows:

• Administer the Standardized Patient Evaluation of Eye Dryness questionnaire. This gauges the frequency and severity of symptoms such as eye grittiness, irritation, burning and fatigue.
• Have technicians elicit from patients additional symptom reporting. Certain symptoms of dry eye disease may be related to one another, so technicians should ask patients specific questions to gather as much information as possible for the surgeon to properly diagnose and treat patients.
  For example:
• Do you experience redness and/or blurriness? If so, are these symptoms chronic, progressive or fluctuating in nature?
• Does your visual quality fluctuate with activities such as reading or driving?
• Are you sometimes unable to tolerate contact lenses?
• Perform meibography on every patient. Coupled with questionnaire results, meibography results can help distinguish the patients with suspected dry eye disease who require further testing, from those with cataracts only.

Patients with symptoms indicative of ocular surface disease must then undergo a battery of diagnostics to help surgeons arrive at a firm diagnosis, as no one test may be enough to diagnose with any certainty. Upon examination, I recommend surgeons:

• Pay close attention to lid margins. Compress the meibomian glands to evaluate the quality and expressibility of the meibum, which should be an olive-oil-like consistency in a healthy eye. I also look for puckering, pitting, capping and/or telangiectasis. In addition, I always examine the height and quality of the tear film. If I see foaminess, then I know bacterial lipases are causing saponification, which needs to be cleared out to create a clean surface near the lid margin.
• Use vital dye staining, such as fluorescein and lissamine green, to check for positive and negative staining. Areas devoid of staining are just as important as positive staining because these areas represent corneal epithelial irregularities, including anterior basement membrane dystrophy and Salzmann nodular degeneration, that can lead to inaccurate diagnostics.
• Administer a tear osmolarity test. This test detects loss of homeostasis and tear film instability. However, surgeons should keep in mind that normal osmolarity does not necessarily mean a non-dry eye, especially if a patient is symptomatic. Other possible diagnoses may include anterior basement membrane dystrophy (ABMD), early MGD, conjunctival chalasis or mild allergic conjunctivitis.
• Perform Placido disc-based topography and carefully inspect axial images. This is a wonderful tool that helps us examine the architecture and key abnormal characteristics of the ocular surface. Placido images should always be evaluated first to assess topography quality. For example, surgeons should be suspicious of hot spots or unique areas of flattening on an axial map that appear as irregular astigmatism. Also, areas of image dropout can be caused by either ocular surface disease or by lid effects that may distort the axial image. Smudged or distorted mires are strongly suggestive of ocular surface pathology, whether classic dry eye disease or ABMD. Finally, if average keratometric values differ significantly between the left and right eyes, this may indicate tear film instability.
• Compare results from multiple diagnostic devices. Inconsistent readings among devices is often a sign of ocular surface issues. For example, if the amount and steep meridian of astigmatism is different on a Lenstar optical biometer (Haag-Streit) compared with the topographer, this should alert surgeons to further investigate the cause. Erroneous keratometric values are often a result of a decreased TBUT or a poor precorneal tear film and, thus, suggestive of ocular surface disease.

Q. Diagnosis should not begin and end at the slit lamp alone. What other measures can surgeons take to detect ocular surface disease?

Yeu: Just as one may not see the forest for the trees, key behaviors are missed when only peering through a high-magnification microscope. Aside from discussing a patient’s symptoms, simply observing him or her during chair time can reveal symptoms of ocular surface disease. Surgeons should look for the frequency and quality of blinks, blepharospasms, vascular injection of eyelid margins or of the conjunctiva/episclera and eye rubbing, all which can signal significant ocular surface issues.

Q. In what ways should surgeons help patients establish a healthy ocular surface in preparation for refractive cataract surgery?

Yeu: Lid margin sterilization with commercial lid wipes or hypochlorous acid lid scrubs are great ways to remove oil, debris and bacteria, especially for patients with scurf and collarettes caused by anterior blepharitis. However, stirring up foreign contaminants too soon before surgery can put patients at a higher risk for infections or complications. Therefore, patients should perform sterilization techniques for the lid flora for a minimum of 3 to 4 weeks before refractive cataract surgery to ensure an optimal ocular surface.

I also use thermal pulsation therapy for patients with dry eye caused by MGD. This device applies heat and pulsed pressure to the inner and outer lids to express the meibum and provide extended relief from symptoms, while also preparing the ocular surface for refractive cataract surgery. I also suggest performing manual expressions in the clinic if surgeons do not have access to thermal pulsation.

Finally, patients can make behavioral and dietary changes to prepare the ocular surface. Taking full blinks is important, as is an omega-3-rich diet with leafy green vegetables, fish and nutraceuticals such as fatty acid supplements.

Q. How long should surgeons spend treating patients before the ocular surface is primed for refractive cataract surgery?

Yeu: Length of treatment depends on the level of dry eye disease and the refractive outcomes patients desire. If a patient has mild anterior blepharitis and opts for manual cataract surgery with a monofocal IOL, then I suggest scheduling the procedure 4 to 6 weeks into the future, and spend these weeks treating accordingly with an antibiotic lid ointment or antimicrobial lid wipes. In this scenario, an additional follow-up visit is not necessary before surgery.

Conversely, if a patient shows staining on the corneal surface, is at a level 2 according to guidelines from the International Task Force Delphi Panel on Dry Eye and is specifically opting for a refractive outcome with, for example, an extended depth of focus IOL, then I will push the procedure date out 6 to 8 weeks and acutely prepare him or her for surgery. I suggest prescribing dry eye therapies such as a short course of steroid drops, custom preservative-free artificial tears and omega-3 fatty acid supplements. I then schedule a follow-up appointment at week 3 to take repeat measurements and assess the success level of the treatment protocol.

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