Free ABO Cataract and Lens Questions and Answers — 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?
- Nuclear sclerotic
- Cortical
- Posterior subcapsular (Correct answer)
- Traumatic rosette
Correct answer: Posterior subcapsular
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?
- Laser photodisruption
- High-frequency ultrasonic vibration (Correct answer)
- Mechanical cutting with a blade
- Chemical dissolution
Correct answer: High-frequency ultrasonic vibration
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?
- SRK/T
- Holladay 1
- Hoffer Q (Correct answer)
- SRK II
Correct answer: Hoffer Q
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?
- Galactosemia
- Rubella infection
- Idiopathic (Correct answer)
- Lowe syndrome
Correct answer: Idiopathic
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?
- Pseudomonas aeruginosa
- Staphylococcus epidermidis (Correct answer)
- Candida albicans
- Streptococcus pneumoniae
Correct answer: Staphylococcus epidermidis
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.
Question 6: Which of the following statements best describes the anatomical and physiological state of the lens nucleus in an elderly patient?
- It has the highest water content and lowest protein concentration.
- It is composed of the youngest lens fibers.
- It has the highest concentration of insoluble proteins and is dehydrated. (Correct answer)
- It is the primary site of metabolic activity in the lens.
Correct answer: It has the highest concentration of insoluble proteins and is dehydrated.
The lens nucleus is formed from the oldest, most compacted lens fibers. With age, these central fibers undergo sclerosis, losing water content and accumulating insoluble proteins, which contributes to the development of nuclear sclerotic cataracts and a decrease in accommodative amplitude.
Question 7: A patient presents 12 hours after cataract surgery with diffuse limbus-to-limbus corneal edema, mild anterior chamber reaction, and no vitritis. The symptoms are improving with topical steroids. This presentation is most consistent with:
- Acute postoperative endophthalmitis
- Toxic Anterior Segment Syndrome (TASS) (Correct answer)
- Retained lens fragment
- Uveitis-Glaucoma-Hyphema (UGH) Syndrome
Correct answer: Toxic Anterior Segment Syndrome (TASS)
TASS is a sterile, non-infectious inflammatory reaction typically occurring within 12-48 hours of anterior segment surgery. It is caused by a toxic substance introduced into the eye, leading to characteristic diffuse corneal edema and a rapid response to intensive topical corticosteroids, distinguishing it from infectious endophthalmitis which has a later onset and involves the vitreous.
Free ABO Cataract and Lens Questions and Answers
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?