Free ABO Cataract and Lens Questions and Answers

Question 1

A 55-year-old patient on long-term systemic prednisone for rheumatoid arthritis presents with a gradual, painless decrease in vision, particularly complaining of glare at night. Which type of cataract is most commonly associated with this clinical history?

Accepted Answer

Posterior subcapsular

Answer

Long-term corticosteroid use, both systemic and topical, is a well-established risk factor for the development of posterior subcapsular cataracts (PSC). These opacities form on the posterior surface of the lens, directly in the nodal point of the eye's optics, leading to significant glare and difficulty with reading vision.

Question 2

What is the primary mechanism by which phacoemulsification removes the crystalline lens?

Accepted Answer

High-frequency ultrasonic vibration

Answer

Phacoemulsification utilizes a hollow titanium needle that vibrates at ultrasonic frequencies (typically 20,000 to 60,000 Hz). This high-frequency vibration creates mechanical energy that emulsifies, or breaks up, the lens material, which is then aspirated through the hollow tip.

Question 3

When calculating intraocular lens (IOL) power for a patient with a very short axial length (<22.0 mm), which of the following formulas is generally considered more accurate?

Accepted Answer

Hoffer Q

Answer

The Hoffer Q formula is a third-generation formula that is specifically optimized for eyes with short axial lengths. It tends to provide more predictable and accurate refractive outcomes in hyperopic eyes, reducing the risk of a postoperative hyperopic surprise that can occur with other formulas in this group.

Question 4

A 2-day-old infant is noted to have bilateral leukocoria. What is the most common cause of bilateral, non-traumatic congenital cataracts?

Accepted Answer

Idiopathic

Answer

While numerous genetic syndromes, metabolic disorders (like galactosemia), and intrauterine infections (like TORCH infections) can cause congenital cataracts, the most common finding is that they are idiopathic, meaning no specific cause is identified. Genetic mutations are often presumed in these cases but may not be part of a known syndrome.

Question 5

A patient develops acute, painful vision loss, hypopyon, and severe intraocular inflammation three days after uncomplicated cataract surgery. What is the most common causative organism for acute postoperative endophthalmitis?

Accepted Answer

Staphylococcus epidermidis

Answer

The most common organisms causing acute postoperative endophthalmitis are coagulase-negative staphylococci, with Staphylococcus epidermidis being the most frequent isolate. These bacteria are part of the normal flora of the patient's own ocular surface and can be introduced into the eye during surgery.

ABO - American Board of Ophthalmology Practice Test

ABO - American Board of Ophthalmology Practice Test

Free ABO Cataract and Lens Questions and Answers