COA Ophthalmic Instruments and Procedures 1 — Questions and Answers
Question 1: What instrument is used to measure the curvature of the anterior corneal surface?
- Keratometer (Correct answer)
- Tonometer
- Retinoscope
- Ophthalmoscope
Correct answer: Keratometer
A keratometer measures the curvature of the anterior corneal surface in two principal meridians.
Question 2: The slit lamp biomicroscope is primarily used to examine which ocular structures?
- Only the retina
- Only the optic nerve
- Anterior and posterior segments of the eye (Correct answer)
- Only the corneal surface
Correct answer: Anterior and posterior segments of the eye
The slit lamp provides magnified illuminated examination of both anterior and posterior eye segments.
Question 3: What is the primary purpose of performing retinoscopy?
- Measure intraocular pressure
- Determine refractive error objectively (Correct answer)
- Photograph the fundus
- Measure corneal thickness
Correct answer: Determine refractive error objectively
Retinoscopy is an objective technique to determine a patient's refractive error by observing the light reflex.
Question 4: Which instrument provides a wide-field inverted view of the fundus?
- Direct ophthalmoscope
- Slit lamp alone
- Binocular indirect ophthalmoscope (Correct answer)
- Autorefractor
Correct answer: Binocular indirect ophthalmoscope
The binocular indirect ophthalmoscope provides a wide-field stereoscopic view of the fundus using a condensing lens.
Question 5: A lensometer (lensmeter) is used to measure which of the following?
- Corneal curvature
- Intraocular pressure
- Prescription power of spectacle lenses (Correct answer)
- Pupil diameter
Correct answer: Prescription power of spectacle lenses
A lensometer measures the sphere, cylinder, axis, and prism of an existing spectacle lens.
Question 6: A-scan ultrasound biometry is primarily performed to measure:
- Corneal curvature
- Axial length of the eye (Correct answer)
- Anterior chamber depth only
- Retinal thickness
Correct answer: Axial length of the eye
A-scan ultrasound measures the axial length of the eye, which is essential for intraocular lens power calculation.
COA Ophthalmic Instruments and Procedures 1
What instrument is used to measure the curvature of the anterior corneal surface?