Patient History and Ophthalmic Examination Techniques Flashcards

A patient reports intermittent visual disturbances described as a 'shimmering arc of light followed by a blind spot lasting 20-30 minutes' with no associated headache. During history-taking, which classification best describes this phenomenon, and what is its significance for the ophthalmic examination?

Answer: Ocular migraine aura (scintillating scotoma) — a neurological phenomenon that does not require emergent fundus examination if aura is consistent and recurrent

Scintillating scotomas (shimmering arcs followed by a transient blind spot lasting 20-30 minutes) are characteristic of ocular migraine aura — a cortical phenomenon originating in the visual cortex, not the eye itself. Unlike amaurosis fugax (seconds to minutes, monocular), this is typically binocular and benign when recurrent and consistent. Fundus examination is not emergent unless the pattern changes. Photopsia from PVD is typically unilateral and associated with floaters.

When performing a confrontation visual field test on a patient with suspected hemianopia, you note the patient correctly identifies fingers in the left and right superior quadrants but misses targets in both inferior quadrants bilaterally. This pattern is MOST consistent with a lesion at which location?

Answer: Bilateral occipital lobe damage affecting the superior calcarine cortex (superior banks of the calcarine fissure)

The inferior visual field is processed by the superior calcarine cortex (superior bank of the calcarine fissure). A bilateral inferior quadrantanopia — loss in both inferior quadrants of both eyes — indicates bilateral damage to the superior calcarine cortex, most commonly from trauma, watershed infarct, or bilateral occipital lesions. This is distinct from Meyer's loop involvement (which produces a superior quadrantanopia in one homonymous hemifield) or chiasmal pathology (which produces bitemporal patterns).

During slit-lamp examination, you observe a thin, grayish-white arc in the peripheral cornea of a 52-year-old patient, separated from the limbus by a clear interval. The patient's history reveals no systemic complaints. This finding is MOST accurately documented as:

Answer: Arcus senilis (corneal arcus) — a lipid deposition that is clinically insignificant in patients over 50 but warrants lipid panel referral if found under age 40

Arcus senilis appears as a grayish-white arc or ring in the peripheral corneal stroma, separated from the limbus by a lucid interval of clear cornea — this is pathognomonic of lipid deposition. In patients over 50, it is a normal aging finding. However, unilateral arcus is a red flag for ipsilateral carotid disease. Kayser-Fleischer rings are golden-brown and best seen with gonioscopy at Descemet's membrane level. Fleischer rings are iron deposits at the cone base in keratoconus, seen with cobalt blue light.

You are performing Goldmann applanation tonometry and notice the mire semicircles are not equal in width — the upper mire is significantly thicker than the lower. The MOST likely cause and the correct corrective action is:

Answer: The tonometer prism is rotated incorrectly for a patient with corneal astigmatism greater than 3 diopters — rotate the prism to align the red mark with the axis of the minus cylinder

Unequal mire widths during Goldmann applanation indicate that the prism is not correctly oriented for the patient's corneal astigmatism. When corneal astigmatism exceeds approximately 3 diopters, the mires become unequal in width. The correction is to rotate the prism so the red mark on the tonometer aligns with the axis of the minus cylinder (or 43° off the plus cylinder axis). Excessive fluorescein causes overly wide and bright mires but they remain roughly equal in width. This adjustment is a critical COT-level skill.

A patient's chief complaint is difficulty reading in dim light that has progressed over 3 years. Best-corrected distance VA is 20/25 OU. Color vision testing with Ishihara plates reveals 8/14 plates missed in the right eye and 6/14 in the left. ERG testing is planned. Which component of the ERG would be MOST affected if this presentation is consistent with rod-cone dystrophy (retinitis pigmentosa)?

Answer: The b-wave under scotopic (dark-adapted) conditions would be reduced or extinguished earlier and more severely than photopic responses, as rods are affected first

In retinitis pigmentosa (rod-cone dystrophy), rods are affected first and more severely than cones — this is the defining characteristic. On full-field ERG, the scotopic (dark-adapted, rod-driven) b-wave is reduced or extinguished early in the disease course, while photopic (cone-driven) responses are relatively preserved until later stages. The a-wave reflects photoreceptor activity (primarily rods in scotopic conditions); the b-wave reflects inner retinal (Müller/bipolar cell) response. The classic ERG finding is a 'negative ERG' in some forms, with preserved a-wave and attenuated b-wave.

During history-taking, a patient reports using timolol 0.5% drops in both eyes for glaucoma. He is scheduled for a routine ophthalmic examination and mentions he recently started a new medication from his cardiologist. Which of the following drug interactions represents the most clinically dangerous combination that the ophthalmic technician should flag before the examination proceeds?

Answer: Timolol + oral verapamil (a calcium channel blocker) — additive cardiac depression that can cause bradycardia, heart block, or cardiac arrest

Topical timolol is a non-selective beta-blocker with significant systemic absorption. Combined with oral calcium channel blockers such as verapamil or diltiazem — which also slow conduction — the additive cardiac depressant effect can cause severe bradycardia, atrioventricular block, or cardiac arrest, particularly in elderly patients. This is a well-documented, life-threatening interaction. The ophthalmic technician should document this combination and alert the supervising physician before proceeding. Timolol + latanoprost is a standard combination; timolol + acetazolamide requires monitoring but is routinely used in glaucoma management.