In this installment of Interventional Mindset, Dr. Preeya K. Gupta reviews clinical pearls for evaluating and optimizing the ocular surface prior to refractive cataract surgery.
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Browse through our videos on a variety of topics within cataract and refractive surgery, glaucoma, and ocular surface disease to learn practical insights into adopting a variety of new surgical techniques and technology.
Pearl 1: Screening and diagnosing ocular surface disease before surgery
Dry eye disease (DED) has the potential to negatively impact surgical outcomes in cataract and refractive patients. The PROOF Study showed that DED was linked to poor visual quality in cataract and refractive patients; despite 20/20 vision, 56% of DED arm complained of moderate or worse blurry vision, compared to only 14% of controls (p<0.001). Consequently, simply testing patients’ visual quality, and using that data as a metric of success of the treatment can cause eyecare practitioners (ECPs) to miss chronic ocular surface disease (OSD).
Additionally, surgeons should be aware that they could encounter refractive surprises caused by hyperosmolarity, which can lead to variability in keratometry measurements and resulting in intraocular lens (IOL) power errors.
Lastly, DED can cause post-operative discomfort and pain in cataract and refractive patients. Dr. Gupta noted that surgeons may encounter these patients coming in and saying that surgery went badly because they are experiencing complications, and when asked what happened they describe dry eye symptoms.
The prevalence of OSD in cataract patients
In a study led by Dr. Gupta and colleagues, the research group evaluated the prevalence of DED in pre-surgical patients using point-of-care testing to diagnose DED. They found abnormal osmolarity in 56.7% of patients and abnormal matrix metalloproteinase 9 (MMP-9) levels in 63.3%. Further, 85% of asymptomatic patients had an abnormal point-of-care test, and 39.2% had corneal staining on presentation. Overall, 80% of patients had at least one abnormal MMP-9, tear osmolarity, or corneal staining test, suggestive of ocular surface dysfunction.
At this moment of time, Dr. Gupta highlighted that it is more common for surgeons to see patients coming in for a cataract evaluation with dry eye than not. In addition, when looking at the number of symptomatic and asymptomatic dry eye patients, about half didn’t present with symptoms. Thus, pre-operative screening is key to treat them in advance and prevent complications and progression.
Pearl 2: Use point-of-care testing to help make the OSD diagnosis
From the TFOS DEWS II definition of dry eye, “Dry Eye is a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film, and accompanied by ocular symptoms, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles.”
With this in mind, when looking at diagnostic tests, Dr. Gupta advised surgeons to perform tests that specifically measure hyperosmolarity and inflammation, as they are helpful in identifying OSD.
Osmolarity testing for DED
An osmolarity test is a point-of-care test that is easily accessible and readily available, it is characteristic of dry eye patients to have a variability of readings within 1 day. Based on her clinical experience, Dr. Gupta uses the osmolarity test as a screening test and any patient with >308mOsm/L or higher, or an inter-eye difference of >8mOsm/L, is suggestive of dry eye disease.
Cut-off values for osmolarity testing:
- Normal: (302.2 + 8.3mOsm/L)
- Mild to moderate: (315.0 + 11.4mOsm/L)
- Severe: (336.4 + 22.3mOsm/L
MMP-9 testing for DED
Another useful diagnostic test to add to the toolbox is MMP-9 testing, which is a point-of-care test that can qualitatively measure MMP-9 levels in 10 minutes. MMP-9 is a non-specific inflammatory marker that has been shown to be elevated in dry eye patients.
Ultimately, point-of-care testing is helpful to diagnose dry eye efficiently and easy to integrate into clinical practice because it is often performed by technicians and interpreted by the ophthalmologist. Point-of-care testing is valuable for diagnosing not only DED, but other OSD as well, and it is effective for screening asymptomatic patients to make a diagnosis before the condition progresses.
Pearl 3: Using an algorithm to screen patients for OSD
To facilitate the process of screening patients, the American Society of Cataract and Refractive Surgeons (ASCRS) Corneal Clinical Committee released the ASCRS Pre-operative OSD Algorithm to help guide cataract and refractive surgeons on how to screen their patients to identify and diagnose OSD, and further, how to perform an exam that specifically targets OSD.
The Pre-operative OSD Algorithm starts with assessing symptoms and signs, such as using osmolarity testing and MMP-9 levels to assess inflammation. Dr. Gupta recommended that surgeons screen for OSD and not just DED because any subtype of OSD can potentially be visually significant.
Next, is the clinical exam, which can be completed using the “LLPP” method to evaluate the patient for ocular surface disease. Dr. Gupta highlighted that, with time and experience, this exam can take just 30 seconds.
The LLPP Method: Look, lift, pull, push:
- Look: Lids, blink, meniscus, lashes, meibomian glands, and interpalpebral cornea/conjunctiva
- Lift (upper lid) and Pull (forward): Examination of superior cornea (epithelial basement membrane dystrophy [EBMD], superior limbic keratoconjunctivitis [SLK]) and lid laxity (floppy eyelid syndrome [FES])
- Push: Meibomian gland expression to measure quality and quantity of secretions.
Following the clinical examination, surgeons can evaluate patients with staining or vital dyes, such as fluorescein or lissamine green, to assess the cornea and measure tear breakup time (TBUT).
Once the patient has been examined, the Pre-operative OSD Algorithm recommends that the surgeon determine the visual significance of OSD. On one hand, patients can have non-visually significant OSD, in which surgery can proceed and the refractive plan finalized. Dr. Gupta advised that these patients can still be counseled that their OSD may worsen following the procedure, and if so, they will start prophylactic treatment.
Conversely, for patients with visually-significant OSD, the surgery and refractive plan may be delayed. Dr. Gupta recommended surgeons counsel the patient on OSD and its impact on surgery. An aggressive treatment regimen can be started to minimize the delay in ocular surgery.
Pearl 4: Treating OSD pre-operatively doesn’t have to be hard
In general, Dr. Gupta organizes the treatment approaches for OSD as either over-the-counter treatments, topical prescription medications, or disease-modifying procedures, which are largely designed to treat meibomian gland disease (MGD).
Anti-inflammatory agents used to treat OSD:
- Cyclosporine 0.05% or 0.09% (Restasis or Cequa): Thought to inhibit T-cell activation and lowers inflammatory cytokines. In clinical studies, it was noted to facilitate an increase in tear production and goblet cell density while decreasing corneal staining. It is FDA-approved to increase tear production in patients whose tear production is presumed to be suppressed due to ocular inflammation.
- Lifitegrast 5% (Xiidra): Is a T-cell integrin antagonist designed to mimic intercellular adhesion molecule 1 (ICAM-1), thereby blocking the interaction between lymphocyte function-associated antigen 1 (LFA-1) and ICAM-1 to potentially reduce the inflammatory response. It is FDA-approved to treat the signs and symptoms of DED.
- Topical steroids: Used to broadly suppress inflammation, surgeons can prescribe pulse dosing during symptom exacerbations. Limitations include intraocular pressure (IOP) elevation, cataract, and infection risk. In late 2020, Eysuvis (loteprednol etabonate ophthalmic suspension) 0.25% was FDA-approved for the short-term (up to 2 weeks) treatment of the signs and symptoms of DED.
Dr. Gupta noted that, in general, she likes to start DED patients on immunomodulators; typically, she recommends lifitegrast because the FDA trial showed improvements in symptoms as early as 2 weeks. Additionally, she starts the patient on topical steroids in a 2- to 3-week tapered dosing regimen. This treatment approach provides both quick symptom relief and resolution of the breakdown on the corneal surface. It is important to address corneal damage because it could potentially interfere with pre-surgical testing, such as topography, biometry, keratometry, etc.
Treatments targeting meibomian gland dysfunction
There are a variety of technologies available to surgeons to treat MGD, and the key principle of most of them is to relieve chronic obstruction and stasis.
Treatment approaches to manage MGD:
- TearCare
- iLux2
- Lipiflow thermal pulsation
- Intense pulsed light (IPL) therapy
- BlephEx and meibomian gland expression
Conclusion
In order to improve both the surgical outcome and patient satisfaction, Dr. Gupta recommends that surgeons screen patients for OSD prior to surgery using point-of-care testing to identify OSD pre-operatively.
Then, surgeons can develop an algorithm (or use the one designed by ASCRS) to assess and diagnose OSD to ensure that they routinely evaluate the ocular surface to prevent missing corneal pathology, dry eye, or MGD.
Finally, rapid rehabilitation and effective treatment of OSD are paramount in pre-surgical patients to minimize delays in the surgery and maximize the treatment outcome.
