Once we determine that a patient needs surgery, we are ready for pre-op testing.
At a bare minimum, you need four things: (1) pre-op H&P; (2) lens calculations; (3) consent; (4) dilated eye exam. Here are some things you should look at for every cataract patient.
- Prior eye trauma/phacodonesis (lens movement)? Could indicate weakness of zonular fibers (dehiscence), which would increase the risk of lens prolapse and a retina fishing expedition (pars plana vitrectomy to remove a dropped lens from the vitreous). While looking through the slit lamp, gently hit the instrument table with your fist or push on the globe with your finger and see if the patient’s lens moves.
- Tamsulosin (Flomax) or other alpha-blocker use? Can lead to floppy iris syndrome, which makes cataract surgery a lot more difficult.
- Pupil Size? <6 mm is generally pretty tough for residents, and may require Malyugin ring / iris hooks to stretch open the iris.
- Aspirin/blood thinners use? Increases risk of intraoperative bleeding.
- Pseudoexfoliation syndrome? Results in poorer dilation and weaker zonules.
- Guttata (indicating reduced endothelial cell count)? A subtle finding for beginning residents, ask your seniors / attendings to show you how to see this. If you do see this, it should prompt you to consider Fuch’s endothelial dystrophy, and minimize phacoemulsification energy to preserve as many remaining endothelial cells as possible.
- Other factors? The full list of things to evaluate before surgery is exhaustive, but a few others to keep in mind are blepharitis, dry eye disease, shallow anterior chamber, high myopia, anterior capsular fibrosis, cortical sclerosis, prior radial keratotomy (RK)/LASIK/PRK, history of uveitis, history of glaucoma, previous vitrectomy, prior intravitreal injections, large brow ridge, inability to lie flat, and careful examination of the posterior segment.
Lens Calculations: Someone will show you how to operate the machine. Essentially, the machine will measure the patient’s optical parameters (axial length, corneal curvature (keratometry), anterior chamber depth, etc.) and calculate an optimal lens power. You will learn all about adjustments for short eyes, long eyes, etc. but this is beyond the scope of this post.
Consent: You will likely have to consent the patient.
- Options: Surgery or wait?
- Benefits: Improved vision (better than 20/40 in 95% of patients)
- Risks: I find that rather than discussing abstract risks, it’s better to give a concrete quantifiable risk number people can understand. You can tell patients there is a 95% chance vision will improve, 4% chance vision will be about the same, 1% chance vision will be worse due to some complication (infection, mechanical complication like capsular tear and subsequent repair surgery).
Dilated Fundus Exam/Other Testing: Every cataract pre-op requires a dilated fundus exam in order to determine if the patient can have surgery. Some patients need additional testing. For example, patients with diabetic retinopathy should have an OCT to look for macular edema, as doing cataract surgery may worsen the swelling.
Days of Examination: POD1, POW1/2, POM1 (day 1, week 1/2, month 1)
Exam: A complete exam is recommended, but the following findings must be carefully checked:
- Intraocular pressure: May be elevated due to retained viscoelastic – consider a brief course of ocular hypotensive drops or push against the wound to make fluid come out (burping)
- Siedel test: Positive test increases risk of eventual hypotony or endophthalmitis. Consider placing a suture to seal the wound (though some wounds tend to eventually seal on its own).
- Corneal edema: Energy delivered during phacoemulsification can cause temporary decreased functioning of the corneal endothelium. This can lead to folds and edema in the cornea. This usually resolves on its own.
- Cells: Some inflammation (1-2+cells) can be expected after cataract surgery, however marked inflammation can be seen in cases with prior history of uveitis, or with extensive duration of phacoemulsification. Consider increasing steroid drops if inflammation is heavy.
- IOL location: Should be verified that the lens optic and haptics are sitting well within the capsular bag.
- Optic nerve head perfusion: Verify that the optic head looks normal (not pale).
Treatment: Standard treatment is as follows, but this varies a lot from institution to institution and patient to patient. These are general guidelines.
- Antibiotic drops: e.g. fluoroquinolone QID for 1-2 weeks
- Steroid drops QID for 1-2 weeks
- NSAID drops QID for 1-2 weeks (some prefer not to use this unless evidence of post op cystoid macular edema [CME])
Patient Instructions: (at least for the 1st week after surgery)
- Avoid bending
- No heavy lifting
- No rubbing eye
- Avoid water in eye (e.g. no swimming and keep water out of eye while showering)
- Consider protective eyewear (e.g. glasses) during the day and eye patch at night
- Have patient return if they experience painful red eyes or rapidly decreasing vision