BLOG: Systemic disease can affect cataract surgery outcomes
As eye care providers, we all know that we are treating the patient in our chair and not an isolated eyeball. However, it is never a bad idea to take a step back and remember that the knee bone is connected to the shin bone, so to speak.
This entry will cover systemic diseases and patient-specific concerns that, when properly addressed, can improve a patient’s postoperative outcome.
Some of the more common systemic diseases are likely what first come to mind: We always consider the stability of our diabetic and hypertensive patients.
If a diabetic patient is on insulin, the addition of a prophylactic postop topical NSAID may be indicated. However, if a patient has known diabetic macular edema prior to surgery it would be appropriate to seek a retinal consult before scheduling cataract extraction (CE). For this and some other retinal conditions, a visit with a retinal specialist may be needed for treatment or simply surgical clearance prior to surgery. Certain treatments are also best coordinated with surgery, such as scheduling CE within 1 week of a planned anti-VEGF injection for additional protective benefit.
When it comes to the day of surgery, few surgeons would be comfortable proceeding if the patient’s blood sugar was below 70 mg/dL or above 350 mg/dL, although variation in these specifications exist among surgery centers.
Blood pressure limits may also vary, but a rule of thumb would be to postpone cataract surgery if the systolic pressure did not fall in the range of 100 mm Hg to 199 mm Hg or the diastolic pressure were not between 50 mm Hg and 100 mm Hg. Pulse is ideally within 50 to 90 beats per minute.
Going a little further, a good practitioner will educate a patient that an elective ocular surgery should not be scheduled if the patient has suffered a heart attack or stroke or undergone cardiac surgery within 90 days. And, as always, the patient must be stable before proceeding.
While less common, it is just as important to consider a patient’s collagen vascular and systemic autoimmune diseases, especially when considering truly elective surgery like LASIK or PRK. These diseases, such as systemic lupus erythematosus, rheumatoid arthritis, psoriatic arthritis, Sjögren’s syndrome, and the HLA-B27 family including ankylosing spondylitis and reactive arthritis, come with a higher risk of ocular complications and are considered a relative (not an absolute) contraindication to laser vision correction. Patients who are not on systemic steroids, are well controlled without high dose or numerous medications, and have few ocular manifestations including no dry eye history can be assessed on a case-by-case basis. Consideration of corneal crosslinking in such a patient follows similar guidelines.
A provider should also be cognizant of additional risk for a patient with compromised immunity, including those undergoing chemotherapy. Because there are as many different treatments as there are types of cancer, each case does need to be considered individually. However, because chemotherapy itself is known to have a negative impact on the body’s ability to fight infection, a general policy is to postpone eye surgery until after active chemotherapy. Because the treatment can also impact the patient’s platelet count, a better policy would be to postpone elective surgery until both the body’s immune system and its ability to properly clot have recovered. Surgery should likely not be performed if a patient’s platelet counts are less than 50,000 per mL. If surgery is strongly desired or even necessary during active chemo treatment, surgery can be cautiously approached if the platelet count is between 50,000 per mL and 80,000 per mL. It should be noted that this range is still considered thrombocytopenia, and medical clearance will be sought from the patient’s oncologist specifically addressing their platelet count and ability to fight infection.
Mini-scleral tunnel, clear corneal incisions
A mini-scleral tunnel (MSTI) tends to be the default incision for cataract surgery at our clinic due to its overall reduced infection rate, fewer dry eye symptoms and more predictable refractive outcome than a clear corneal incision (CCI). This is especially desirable if the patient has no significant against-the-rule corneal astigmatism.
Keeping this in mind, CCIs certainly have their place; they are the go-to method for minimally invasive glaucoma surgery (MIGs) procedures such as the iStent (Glaukos) or Hydrus (Ivantis) and are desired for end-stage glaucoma patients to best preserve scleral real estate if a future trabeculectomy or tube is ever needed.
Specific placement of a CCI can be used to reduce about 0.25 D to 0.5 D of corneal astigmatism for a better refractive outcome in certain patients, and some surgeons prefer CCI because they are simply more adept at this procedure. (Another potentially time-saving referral would be to send an advanced glaucoma patient to a glaucoma specialist if considering cataract surgery, especially if they have not yet been established with one. A specialist may recommend a joint procedure for these patients such as cataract extraction (CE) and trabeculectomy, especially in advanced cases that are beyond MIGs, which are only approved for mild to moderate glaucoma.)
For our immunocompromised patients, we may recommend a CCI to avoid vasculature and topical anesthetic over the needle stick of a retrobulbar block. Topical anesthesia can also be chosen for our truly monocular patients who would be completely without visual feedback for several hours after injected anesthesia but would have some visual recovery faster with topical-only CE. In such cases, the surgeon can attempt topical anesthesia; however, the patient is educated that this comes with increased risk and time, and the surgeon may stop the procedure if the patient is moving too much.
Next time we will discuss further concerns such as infectious disease, patient mental status and patient physical ability.