Mixed Deck — All COA Topics Flashcards

Which of the following symptoms requires prompt attention?

Answer: Sudden loss of vision

Explanation: Sudden loss of vision is a symptom that requires prompt attention because it can indicate a serious condition that needs immediate medical intervention. While the other symptoms are concerning, sudden vision loss is most urgent.

What does the abbreviation 'BCVA' stand for in an ophthalmic record?

Answer: Best corrected visual acuity

BCVA stands for Best Corrected Visual Acuity — the sharpest vision a patient can achieve with optimal spectacle or contact lens correction. It is the standard metric for assessing visual function.

When administering the Ishihara color vision test, which of the following is a critical procedural step for ensuring accuracy?

Answer: Testing each eye individually at a specific reading distance

Proper procedure for the Ishihara test requires testing each eye separately. The test should be conducted in adequate, daylight-like illumination, at a distance of about 75 cm, and the patient should identify the number within about three seconds per plate without coaching or tracing. These standardized conditions are necessary for a valid assessment of congenital red-green color vision defects.

The Hirschberg test estimates the angle of strabismus by observing corneal light reflections. If the corneal reflex appears at the pupil margin of the right eye and centered in the left eye, approximately how many prism diopters of deviation is estimated?

Answer: 15–20 prism diopters

In the Hirschberg test, a decentered corneal light reflex at the pupil margin corresponds to approximately 15 prism diopters (pd) of deviation. Each millimeter of decentration equals approximately 15 pd (some sources use 7° or 22 pd/mm depending on reference).

Of the following conditions, which one is least likely to cause transient loss of vision?

Answer: Thyroid disorder

Explanation: Thyroid disorders can lead to various ocular manifestations such as proptosis (bulging eyes) and double vision, but they are less likely to cause transient loss of vision compared to conditions like carotid artery disease or migraine, which can directly affect blood flow to the eyes or brain.

The Humphrey Visual Field Analyzer performs which type of perimetry?

Answer: Static automated perimetry

The Humphrey Field Analyzer uses static automated perimetry, presenting stationary stimuli at varying intensities.

The term used to refer to symptoms due to uncorrected refractive error is ______ :

Answer: Asthenopia

Explanation: Asthenopia refers to symptoms like eye strain, headaches, or discomfort due to uncorrected refractive error, particularly focusing difficulties.

Which of the following is a key principle of applanation tonometry, based on the Imbert-Fick law?

Answer: Measuring the force required to flatten a specific area of the cornea

The Imbert-Fick principle, on which Goldmann applanation tonometry is based, states that the pressure inside an ideal sphere is equal to the force necessary to flatten its surface divided by the area of flattening (P = F/A). Therefore, the tonometer measures the external force required to flatten a 3.06 mm diameter area of the central cornea to calculate the internal pressure.

The slit lamp biomicroscope is primarily used to examine which ocular structures?

Answer: Anterior and posterior segments of the eye

The slit lamp provides magnified illuminated examination of both anterior and posterior eye segments.

A patient calls stating they suddenly see 'flashing lights and a curtain' over the vision in their right eye. Which of the following is the MOST appropriate action for the ophthalmic assistant to take?

Answer: Instruct the patient to come to the office for an emergency evaluation immediately.

The symptoms of flashing lights and a curtain in the vision are classic signs of a potential retinal tear or detachment, which is an ocular emergency requiring immediate evaluation and possible treatment to prevent permanent vision loss.

Which device is used to calculate intraocular lens power before cataract surgery?

Answer: Optical biometry device (e.g., IOL Master)

Optical biometry devices measure axial length and corneal curvature to calculate the appropriate IOL power.

What is the recommended first step before performing Goldmann applanation tonometry?

Answer: Instill a topical anesthetic and fluorescein

GAT requires topical anesthesia for patient comfort and fluorescein sodium to create the characteristic tear film meniscus rings that enable proper mire alignment. Both are instilled before the procedure.

In ocular motility testing using the H pattern (nine cardinal positions of gaze), which muscle is being evaluated when the patient looks to the right and UP?

Answer: Right superior rectus (SR) and left inferior oblique (IO)

In right and up gaze, the right superior rectus is the primary elevator and the left inferior oblique is the primary elevator of the fellow eye in that conjugate gaze position. The superior rectus and inferior oblique are yoke muscles (Hering's law) for upgaze.

The trabecular meshwork is clinically significant because it:

Answer: Is the primary drainage site for aqueous humor

The trabecular meshwork drains approximately 80–90% of aqueous humor into Schlemm's canal, and its dysfunction elevates IOP.

The avascular cornea receives oxygen primarily from which sources?

Answer: Tear film and aqueous humor

The cornea gets oxygen anteriorly from the tear film and posteriorly from the aqueous humor due to its avascularity.

What is an important question to ask a patient that complains of a "red eye"?

Answer: Do you have blurred vision?

Explanation: When a patient complains of a "red eye," it's essential to ask about associated symptoms like blurred vision, as it could indicate more serious underlying conditions such as corneal inflammation, uveitis, or glaucoma.

What is the primary clinical reason for performing a stereoacuity test such as the Randot or Titmus Fly test?

Answer: To assess binocular fusion and depth perception

Stereoacuity tests measure fine depth perception, which requires binocular fusion and intact sensory and motor alignment. They are used to assess amblyopia treatment outcomes, strabismus, and binocular vision disorders.

What is the primary function of the Goldmann applanation tonometer?

Answer: Measure intraocular pressure

The Goldmann applanation tonometer is considered the gold standard for measuring intraocular pressure.

The vitreous humor consists primarily of:

Answer: Water with collagen fibrils and hyaluronic acid

The vitreous is approximately 99% water supported by a framework of collagen fibrils and hyaluronic acid.

A 5-year-old child is being tested for stereopsis. Which of the following tests would be most appropriate for this age group?

Answer: Titmus Fly Test

The Titmus Fly Test is a common and effective method for evaluating stereopsis (depth perception), especially in children. It uses polarized glasses and features a large, three-dimensional fly, as well as animal figures and graded circles, which are engaging for young patients and do not require them to identify letters or numbers. The Amsler grid tests for central field defects, confrontation fields test peripheral vision, and the Snellen chart measures visual acuity.