Board Certified Ophthalmologist Lens and Cataract 2 — Questions and Answers
Question 1: Which organism is most frequently isolated in acute postoperative endophthalmitis after cataract surgery?
- Staphylococcus aureus
- Coagulase-negative staphylococci (Correct answer)
- Streptococcus pneumoniae
- Pseudomonas aeruginosa
Correct answer: Coagulase-negative staphylococci
The Endophthalmitis Vitrectomy Study found coagulase-negative staphylococci (mainly S. epidermidis) in about 70% of culture-positive cases.
Question 2: A patient has diffuse limbus-to-limbus corneal edema and an anterior chamber reaction 18 hours after uneventful phacoemulsification, with no vitritis. What is the most likely diagnosis?
- Acute bacterial endophthalmitis
- Retained lens fragment
- Toxic anterior segment syndrome (Correct answer)
- Herpetic endotheliitis
Correct answer: Toxic anterior segment syndrome
TASS starts within 12-48 hours with widespread corneal edema from endothelial toxicity, and the inflammation stays in the anterior segment.
Question 3: Intraoperative floppy iris syndrome is most strongly associated with which systemic medication?
- Finasteride
- Metoprolol
- Tamsulosin (Correct answer)
- Sildenafil
Correct answer: Tamsulosin
Tamsulosin selectively blocks alpha-1A receptors in the iris dilator muscle, which causes billowing, prolapse and progressive miosis.
Question 4: During phacoemulsification the posterior capsule ruptures and a large nuclear fragment drops into the vitreous. What is the most appropriate next step?
- Chase the fragment with the phaco tip through the capsular tear
- Use irrigation to float the fragment up into the anterior chamber
- Do an anterior vitrectomy, place a suitable IOL, close, and refer for pars plana vitrectomy (Correct answer)
- Abort surgery and leave the eye aphakic without vitrectomy
Correct answer: Do an anterior vitrectomy, place a suitable IOL, close, and refer for pars plana vitrectomy
Trying to retrieve a posteriorly dislocated nucleus from the anterior approach risks retinal tears, so the fragment should be removed later by pars plana vitrectomy.
Question 5: Clinically significant pseudophakic cystoid macular edema (Irvine-Gass syndrome) most commonly peaks at what time after surgery?
- 1-3 days
- 4-6 weeks (Correct answer)
- 6-9 months
- 2-3 years
Correct answer: 4-6 weeks
Irvine-Gass CME usually appears 4-12 weeks after surgery and is most common around 4-6 weeks.
Question 6: During cataract surgery the anterior chamber suddenly shallows, the eye becomes firm, and the red reflex darkens. What is the most important immediate action?
- Increase bottle height to deepen the chamber
- Immediately close all incisions (Correct answer)
- Do a posterior sclerotomy at once to drain the blood
- Inject more viscoelastic and continue phaco
Correct answer: Immediately close all incisions
A suspected suprachoroidal hemorrhage requires rapid wound closure to tamponade the bleeding and prevent expulsion of intraocular contents.
Question 7: What is the most common cause of a corneal incision thermal burn during phacoemulsification?
- Too much irrigation flow
- Too low ultrasound power
- Occlusion of aspiration with dense viscoelastic or a tight incision that restricts flow (Correct answer)
- Using a dispersive viscoelastic for endothelial protection
Correct answer: Occlusion of aspiration with dense viscoelastic or a tight incision that restricts flow
Reduced fluid flow around the vibrating tip stops heat dissipation, which leads to collagen contracture and wound burn.
