Sunday, September 18, 2005

Chapter 1 Assessment - Evaluation of Patients with Cataract

Ask yourself?
  • Is the cataract causing the visual decline?
  • Is the cataract secondary to a systemic or ocular condition?
  • Could the eye/patient survive cataract surgery if indicated?
  • Surgery is indicated for patients with symptoms that disrupt their daily activities.

Symptoms of a cataract

  • Visual acuity -- usually a gradual decline over years with posterior sub-capsular cataract (PSCC). Visual Acuity (VA) can decline over days. Often near VA decline is greater than far VA decline in PSCC.
  • Glare -- night driving problems, halos, especially with PSCC and cortical.
  • Myopic shift -- “second sight”, especially in nuclear sclerotic cataract.
  • Diplopia -- monocular, especially in PSCC and cortical

Indications for cataract surgery

  • Functional, functional, functional.
  • Document difficult with reading, driving, glare, recognizing faces
  • If the patient is having difficulty with daily tasks, then this is the indication for surgery.
  • Read: US Dept. of Health and Human Services Practice Clinical Guideline #4 - Cataract in Adults: Management of Functional Impairment
  • Must document functional decline (in Iowa, we use a form with the patient's signature)
  • Best corrected Visual Acuity <= 20/50 at far or near acceptable to VA Hospital, Medicare, etc.
  • Best corrected Visual Acuity > 20/40. Concentrate documentation on functional disability, eg. monocular diplopia, glare disability, occupational impairment, ect...
  • Uncommon indications: lens induced disease, eg. phacomorphic glaucoma, or medical need to visualize the fundus, eg. view to help exam for diabetic retinopathy.

General Issues

  • Can your patient lay flat for 30-60 minutes? The surgery may be more complicated when there is back pain, chronic obstructive pulmonary disease (COPD), or Congestive Heart Failure(CHF). Consult with their family physician to help address general medical issues before surgery.
  • Can your patient lay still? The case may be more difficult with young males, tremor, or claustrophobia. If laying still is a problem, then consider general anesthesia for the patient's safety and to reduce intraoperative complications. The risks and benefits of general anesthesia should be discussed with the patient.
  • Look at the medicine list. Is your patient taking coumadin, Plavix, or aspirin (ASA), and if so can they/should they stop these anti-coagulants? Is the patient taking Flomax (tamsulosin) for their prostate? – Flomax has been associated with intraoperative floppy iris syndrome (IFIS). [VIEW VIDEO IN EXTERNAL VIDEO PLAYER]:

    consider iris retractor to help with IFIS
  • Chronic Steroid Use – usually no need for stress steroid dose unless patient is scheduled for general anesthesia.
  • Does your patient have latex and drug allergies? Surgery by have to performed with latex-free materials and gloves.
  • Can your patient tolerate their post operative care? Do they need help putting in their drops? Monocular patients may need significant post-operative help (eg. admission if patched post-operatively).

Past Ocular History

  • Complete the manifest refraction in both eyes. Fellow eye (non-operative eye) refraction may be needed to help with intra-ocular lens (IOL) selection. Document the VA in both dim and bright light conditions (room lights on and trans-illuminator 45 degrees to side) to check for glare symptoms. When the vision is poor – document no improvement with /- 3 diopters lenses.
  • Examine Pupils. Check relative afferent pupil defect (RAPD) – as always critical – especially if patient's vision remains poor after surgery. Dilated pupil Size – useful when selecting among surgeons (see difficulty factors).
  • Check Confrontation Visual Field (CVF). If the cataract is dense, then check Light Perception (LP) in all four quadrants (instead of echo).
  • Keratometer readings of both eyes -- do prior to other cornea manipulations.
  • External Exam - Document if there is abnormal tear function, lid malposition/exposure, blepharitis, or spasm. If the patient has a prominent brow, then consider a temporal approach or schedule for a more experienced surgeon.
  • Slit Lamp Exam - Document cornea guttata, posterior-polymorphous dystrophy (PPMD), map-dot-fingerprint dystrophy (MDF), or corneal exposure problems. Document lens hardness, phacodonesis, pseudoexfoliation( PXF), or posterior polar cataract.
  • Gonioscopy - Important if you need to place an anterior chamber lens. Especially important with history of uveitis and possible anterior synechiae.
  • Dilated Fundus Exam - Not mandatory to complete a dilated fundus exam if you or trusted colleague have looked recently. Dilation the day before will inhibit dilation the day of surgery, which is undesireable. If the vision is poor, then ask yourself if the poor view matches the poor vision of the patient. If not, then the cataract may not be the cause of visual decline. Look carefully at patients with diabetes, and consider pre-operative fluorescein angiogram or OCT. Document normal macula, appearance of optic nerve, and posterior vitreous detachment if present.
  • Special Tests: The use of the potential acuity meter (device that projects an eye chart around lens onto the retina) is rarely helpful. With no view, consider echography, but echography is not necessary without RAPD and there is LP in four quadrants on CVF. Specular microscopy for corneal endothelial cell count is rarely needed, e.g. FDA Studies, Fuchs' dystrophy. Consider pachymetry in patients with corneal edema, e.g. Fuchs' dystrophy.



Blogger Tom said...

To get an idea of what the guttata look like, you might want to check out the guttae video at rootatlas:

corneal guttae video

Shows the beaten-bronze appearance that you look for prior to cataract surgery. You don't want to be suprised by a decompensating cornea after surgery!

8:27 AM  
Blogger Dr_Triple said...

One complication of mature cataract is phacomorphic glaucoma in which the cataract will become large enough to push the iris forward. Normally the aqueous humor will pass from the posterior chamber to the anterior chamber through a space between the lens and the iris. With phacomorphic glaucoma, the mature lens will be very close to the iris obliterating this space and block the flow of aqueous humor behind the iris causing high intraocular pressure

9:51 AM  

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