What laboratory tests should be ordered preoperatively for eye surgery?

Preoperative Laboratory Testing for Eye Surgery

For patients undergoing eye surgery, routine preoperative laboratory testing is not recommended unless specific medical conditions or risk factors warrant testing. 1, 2

General Approach to Preoperative Testing for Eye Surgery

Cataract Surgery (Most Common Eye Surgery)

• Patients in their usual state of health undergoing cataract surgery do not require any preoperative laboratory testing 1, 2
• A large randomized controlled trial with over 19,000 cataract surgery patients showed no difference in outcomes between patients who received preoperative testing versus those who did not 1
• A 2012 Cochrane review reinforced this finding, confirming that routine preoperative testing does not improve outcomes for cataract surgery patients 1

Other Eye Surgeries

• For non-cataract eye surgeries, the same principles apply - testing should be based on patient-specific factors rather than performed routinely 2
• Eye surgery is generally considered low-risk surgery from a cardiovascular perspective, which influences testing recommendations 2

Specific Laboratory Tests

Complete Blood Count (CBC)

• Only order CBC for patients with:
  • Diseases that increase risk of anemia (liver disease, hematologic disorders) 2
  • History of anemia or recent blood loss 2
  • When significant perioperative blood loss is anticipated (rare in most eye surgeries) 2

Coagulation Studies (PT/PTT)

• Reserve coagulation testing for patients with:
  • History of bleeding disorders 2, 3
  • Medical conditions predisposing to coagulopathy (e.g., liver disease) 1, 2
  • Patients taking anticoagulants 1, 2
• Indiscriminate preoperative coagulation testing has poor yield (0.2% clinically significant findings in patients without bleeding history) and high false-positive rates 4

Electrolytes and Renal Function

• Only order for patients with:
  • Risk factors for electrolyte abnormalities 2
  • Renal impairment 2
  • Medications that affect electrolytes (diuretics, ACE inhibitors, ARBs, NSAIDs, digoxin) 2
  • Hypertension, heart failure, chronic kidney disease, complicated diabetes mellitus, or liver disease 2

Glucose Testing

• Random glucose testing only for patients at high risk of undiagnosed diabetes 1, 2
• For patients with known diabetes, HbA1C testing only if results would change perioperative management 1, 2

Special Considerations

Electrocardiogram (ECG)

• Not indicated for asymptomatic patients undergoing low-risk surgery like eye procedures 2
• Consider ECG for:
  • Patients with signs or symptoms of cardiovascular disease 2
  • Patients older than 65 years with risk factors 1
  • Patients with diabetes, hypertension, chest pain, congestive heart failure, smoking history, peripheral vascular disease 1

Chest Radiography

• Not recommended routinely for asymptomatic, otherwise healthy patients 2
• Only indicated for patients with new or unstable cardiopulmonary signs or symptoms 2

Common Pitfalls to Avoid

• Ordering "routine" preoperative labs for all eye surgery patients wastes resources and may lead to false-positive results requiring unnecessary follow-up 1, 2
• Relying on abnormal lab values without clinical correlation can lead to unnecessary delays in surgery 4
• Assuming that more testing equals better care - evidence shows that targeted testing based on clinical factors leads to better outcomes than universal screening 2
• Failing to consider that false-positive results from unnecessary testing can lead to additional testing, increased patient anxiety, and surgical delays 4

Algorithm for Preoperative Testing Decision-Making

1. Determine if the patient is undergoing cataract surgery

   • If yes, and patient is in usual state of health → No preoperative testing needed 1

2. For all other eye surgeries, assess for specific risk factors:

   • History of bleeding disorders → Consider coagulation studies 1, 2
   • Anticoagulant use → Consider coagulation studies 1, 2
   • Anemia or conditions predisposing to anemia → Consider CBC 2
   • Renal disease or medications affecting electrolytes → Consider basic metabolic panel 2
   • Poorly controlled diabetes → Consider glucose or HbA1C 1, 2
   • Cardiovascular disease → Consider ECG if symptoms or multiple risk factors 1, 2

3. If none of these specific indications are present → No preoperative testing needed 2