Routine preoperative labs (ECG, CBC, electrolytes, creatinine, BUN, blood glucose and others) do not reduce postoperative complications and are not cost effective.
Systemic diseases and medications are taken into consideration prior to surgery:
- Diabetic patients should be scheduled early in the morning to avoid hypoglycemia.
- Hypertension medications should be continued through the morning of surgery. Blood pressure control limits the risk of suprachoroidal hemorrhage.
- Although respiratory diseases are not absolute contraindications, cough can make surgery more difficult.
- Patients can typically continue their anticoagulation regimen prior to surgery as there is a low risk of bleeding with cataract surgery.
- Aspirin can safely be continued through the day of surgery, but stopping aspirin within 2 weeks of surgery is also associated with low risk.
- Warfarin similarly appears to be associated with low risk whether continued or discontinued before surgery.
- Clopidogrel is less well studied in cataract surgery but can usually be continued in patients on chronic antiplatelet therapy.
Certain preoperative medications increase the risk of intraoperative floppy iris syndrome (IFIS):
IFIS includes a triad of a flaccid iris that moves out through the surgical incision, iris prolapse, and intraoperative pupillary constriction.
- IFIS increases difficulty of the surgical procedure and also increases the risk of posterior capsule rupture, retinal detachment, and endophthalmitis.
- Alpha-1 antagonists increase the risk of IFIS.
- Tamulosin (Flomax) increases risk of IFIS about 2 fold, but stopping tamulosin before surgery does not appear to reduce risk.
- Palliperidone and risperidone (second generation antipsychotics) also increase risk of IFIS.
- Intraoperative techniques to reduce complications from IFIS include use of iris retractors, low flow fluidics, and preoperative cycloplegia. Foreknowledge of the risk of IFIS and use of these precautions can reduce risk of posterior capsule rupture to less than 1%.
All patients need a comprehensive preoperative ocular exam including:
- Refraction of both eyes
- Assessment for dry eye, which can impair accurate keratometry
- Assessment for blepharitis, which can increase the risk of postoperative endopthalmitis
- Assessment for phacodenesis (lens vibration with eye movement)
- Evaluation of dilated pupil size
- A full dilated fundoscopic exam
Patients also need to be evaluated to determine the type of lens and prescription strength to be used during surgery.