Mixed Deck — All ABO Topics Flashcards

Which condition presents with a white pupillary reflex in a child?

Answer: Retinoblastoma

Retinoblastoma is the most common primary intraocular malignancy in children, and its classic presenting sign is leukocoria, or a white pupillary reflex. This 'cat's eye reflex' occurs when light reflects off the tumor mass within the eye. Early detection is critical for successful treatment and preservation of vision and life.

According to the Pediatric Eye Disease Investigator Group (PEDIG) Amblyopia Treatment Studies, which of the following is true regarding the treatment of moderate amblyopia (20/40 to 20/80) in children aged 3 to <7 years?

Answer: Patching for 2 hours daily was found to be as effective as patching for 6 hours daily.

A landmark PEDIG study (ATS1) demonstrated that for children aged 3 to <7 years with moderate amblyopia (visual acuity 20/40 to 20/80), patching the sound eye for 2 hours per day was as effective as patching for 6 hours per day. This finding changed clinical practice, allowing for reduced treatment burden with similar efficacy. Subsequent studies showed atropine to be a comparable alternative to patching, not superior. Other studies have also shown that a significant number of children improve with optical correction alone, which should be tried first.

What is the most common cause of amblyopia in children?

Answer: Strabismus

Amblyopia, or 'lazy eye,' is reduced vision in an eye that did not develop normal sight during childhood. Strabismus, a misalignment of the eyes, is the most common cause because the brain suppresses the image from the misaligned eye to avoid double vision, leading to a lack of visual stimulation and development in that eye. Early detection and treatment are crucial for improving visual outcomes.

A patient's prescription is -2.00 -1.00 x 180. What is the total power of this lens in the 90-degree meridian?

Answer: -3.00 D

The power in the principal meridians of a spherocylindrical lens can be determined by analyzing the prescription. The sphere power (-2.00 D) is present in all meridians. The cylinder power (-1.00 D) is at its maximum at 90 degrees away from its axis. The axis is 180, so 90 degrees away is the 90-degree meridian. Therefore, the total power in the 90th meridian is the sum of the sphere and cylinder powers: -2.00 D + (-1.00 D) = -3.00 D.

During gonioscopy, what is the most posterior structure visible in a normal, open angle?

Answer: Ciliary body band

The structures of the angle from posterior to anterior are: Ciliary body band, Scleral spur, Trabecular meshwork, and Schwalbe's line. Therefore, the ciliary body band is the most posterior structure.

The classic triad of signs for Horner's syndrome consists of ptosis, miosis, and which of the following?

Answer: Anhidrosis

Horner's syndrome is caused by a disruption of the oculosympathetic pathway. This results in the characteristic triad of ipsilateral ptosis (mild drooping of the upper eyelid due to paralysis of Müller's muscle), miosis (a constricted pupil due to unopposed action of the parasympathetic system), and anhidrosis (decreased sweating on the affected side of the face). [9, 10, 12]

Which test is most useful for evaluating posterior uveitis?

Answer: Fluorescein angiography

Fluorescein angiography is a highly useful diagnostic tool for evaluating posterior uveitis. This test involves injecting a fluorescent dye into the bloodstream and taking rapid photographs of the retina. It helps visualize the retinal and choroidal vasculature, detect leakage from inflamed vessels, identify areas of ischemia, and assess macular edema, all of which are crucial for diagnosing and managing posterior segment inflammation.

When interpreting a Humphrey Visual Field (HVF) 24-2 test for a glaucoma suspect, which of the following patterns is most characteristic of early glaucomatous damage?

Answer: A nasal step respecting the horizontal midline

Early glaucomatous visual field defects typically correspond to the pattern of nerve fiber layer loss. A nasal step, which is a scotoma just above or below the horizontal midline in the nasal field, is a classic early sign. This occurs due to damage to the arcuate nerve fibers. A central scotoma is more typical of macular disease or advanced glaucoma. Bitemporal hemianopsia suggests a chiasmal lesion. An enlarged blind spot can be seen in glaucoma but is less specific than a nasal step.

What is the most appropriate management for a chalazion?

Answer: Warm compresses

A chalazion is a chronic, sterile lipogranulomatous inflammation of a meibomian gland, often presenting as a painless lump on the eyelid. The most appropriate initial management involves applying warm compresses multiple times a day. This helps to soften the hardened secretions, promote drainage of the blocked gland, and reduce inflammation, often leading to resolution without further intervention.

A 65-year-old man presents to the emergency department with a 2-hour history of sudden, profound, and painless vision loss in his left eye. His visual acuity is hand motion. Fundus examination reveals diffuse retinal whitening, arteriolar attenuation, and a prominent 'cherry-red spot' in the macula. What is the most critical immediate step in this patient's management?

Answer: Immediate referral for a comprehensive stroke workup.

The patient's presentation is classic for a central retinal artery occlusion (CRAO), which is considered an ocular emergency analogous to an acute ischemic stroke. Immediate referral to a stroke center for evaluation is critical to identify the embolic source and reduce the high risk of a subsequent, potentially fatal, cerebral or myocardial infarction. While treatments like paracentesis or ocular massage exist to dislodge the embolus, their efficacy is debated and secondary to the systemic evaluation. Steroids are for arteritic causes (like GCA), which must be evaluated but the stroke workup is the priority for all patients. Vitrectomy has no role in acute CRAO management.

Retinoblastoma results from biallelic inactivation of which tumor suppressor gene?

Answer: RB1

Retinoblastoma results from biallelic inactivation of the RB1 tumor suppressor gene, illustrating Knudson's classic 'two-hit' model of carcinogenesis.

A patient has a steep vertical corneal meridian and a flat horizontal meridian. This type of astigmatism is known as:

Answer: With-the-rule astigmatism

With-the-rule (WTR) astigmatism is the most common type, where the vertical corneal meridian is steeper (has more power) than the horizontal meridian. This is typically corrected with a minus cylinder lens at or near the 180-degree axis.

An 80-year-old male with a history of atrial fibrillation presents with sudden, profound, painless vision loss in his right eye. Fundus exam reveals a pale retina and a 'cherry-red spot' in the macula. What is the most likely diagnosis?

Answer: Central retinal artery occlusion (CRAO)

A central retinal artery occlusion (CRAO) presents with acute, painless, severe vision loss. The cherry-red spot occurs because the macula receives its blood supply from the underlying choroid, so it remains red while the surrounding ischemic retina becomes pale and opaque.

Which of the following optical principles correctly describes the correction for hyperopia?

Answer: A converging (convex) lens is used to move the focal point forward onto the retina.

In hyperopia (farsightedness), light entering the eye focuses at a point behind the retina. To correct this, a converging lens (convex or 'plus' lens) is used. This lens adds focusing power, bending the light rays more strongly to move the focal point forward so that it lands directly on the retina.

Which of the following findings is the defining feature that differentiates proliferative diabetic retinopathy (PDR) from severe non-proliferative diabetic retinopathy (NPDR)?

Answer: Neovascularization of the disc (NVD)

The hallmark of proliferative diabetic retinopathy is neovascularization, which is the growth of new, abnormal blood vessels. These can occur on the optic disc (NVD) or elsewhere on the retina (NVE) and are a response to widespread retinal ischemia.

Which B-scan ultrasonography finding is most characteristic of choroidal melanoma?

Answer: Low-to-medium internal reflectivity with acoustic hollowing and choroidal excavation

Choroidal melanoma characteristically shows low-to-medium internal reflectivity with acoustic hollowing (angle kappa) and choroidal excavation on standardized A/B-scan ultrasonography.

The Collaborative Ocular Melanoma Study (COMS) demonstrated equivalence between enucleation and which treatment for medium-sized choroidal melanoma?

Answer: I-125 episcleral plaque brachytherapy

COMS demonstrated that I-125 episcleral plaque brachytherapy provides equivalent 5-year overall survival to enucleation for medium-sized choroidal melanomas.

Conjunctival melanoma most frequently arises from which precursor lesion?

Answer: Primary acquired melanosis (PAM) with atypia

Conjunctival melanoma most commonly (75%) arises from primary acquired melanosis with atypia, which carries a significant risk of malignant transformation proportional to the degree of cytologic atypia.

A patient with dry eye disease has rapid tear break-up time but normal Schirmer's test results. Examination reveals inspissated meibomian glands. This presentation is most consistent with which type of dry eye?

Answer: Evaporative dry eye

This patient has evaporative dry eye, most commonly caused by meibomian gland dysfunction (MGD). The glands produce a deficient lipid layer for the tear film, leading to rapid evaporation and instability (short tear break-up time), even if the aqueous production (measured by Schirmer's) is normal.

What is the most common orbital malignancy in adults?

Answer: Lymphoma

Lymphoma is the most common orbital malignancy in adults, typically presenting as a painless salmon-colored subconjunctival or orbital mass in older patients.