Questions and Answers
What is the uveal tract made up of?
Iris, Ciliary body, Choroid
What is happening in the case of bleeding in small conjunctival or Tenon's vessels?
This is not sclera bleeding.
What percentage of refractive power does the cornea provide?
2/3
What percentage of refractive power does the lens provide?
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What is emmetropia?
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What is hyperopia?
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What is myopia?
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What is astigmatism?
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What happens in presbyopia?
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What is visual acuity (VA)?
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When is testing visual acuity most critical?
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What is the purpose of anterior chamber depth assessment?
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What is the normal range of intraocular pressure (IOP)?
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What is the use of tropicamide?
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What is the purpose of proparacaine HCl?
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What is considered normal visual acuity?
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What is legal blindness?
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What are the steps for visual acuity testing?
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What term describes adhesions of the iris to the lens of the eye?
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Where must the lesion be located if a patient is presenting with an APD?
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How many cardinal fields of vision are there?
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How many positions of gaze are there?
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What is the purpose of setting the diopter wheel during an exam?
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Study Notes
Eye Structures and Functions
- Uvea/Uveal Tract: Comprises the iris, ciliary body, and choroid.
- Vision Terminology: Cornea provides 2/3 of the refractive power while the lens contributes 1/3.
Vision Conditions
- Emmetropia: The ideal relationship between the refractive power and eye shape for proper light focusing on the retina.
- Hyperopia (Farsightedness): Caused by a short eye resulting in images focusing behind the retina; corrected with convex lenses.
- Myopia (Nearsightedness): Caused by an elongated eye with images focusing in front of the retina; corrected with concave lenses.
- Astigmatism: Results from irregular curvature of the cornea or lens, leading to distorted vision.
- Presbyopia: Loss of lens accommodation around mid-40s, typically affecting near vision; correction includes glasses, contacts, or refractive surgery, but not for presbyopia itself.
Visual Acuity and Testing
- Visual Acuity (VA): Measures the smallest identifiable object at a specific distance; important to include corrections if needed.
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Basic Terminology:
- OD = Oculus Dexter (right eye)
- OS = Oculus Sinister (left eye)
- OU = Oculus Uterque (both eyes)
- cc = with correction
- sc = without correction
- Critical Age for Testing: Visual acuity testing is crucial in children before age 7.
- Testing Methods: Includes confrontation visual field testing, color vision testing, fluorescein staining, and upper lid eversion.
Pressure and Dilation
- Tonometry: Measures intraocular pressure (normal range 8-21 mmHg), essential for glaucoma assessment.
- Mydriatic Drops (Tropicamide): Used for pupil dilation to enhance eye visualization during exams.
- Topical Anesthetic (Proparacaine HCl): Applied for eye examinations requiring contact.
Visual Acuity Measurement
- Normal Visual Acuity: "Normal" defined as 20/20 but can range from 20/12 to 20/25.
- Moderate/Low Vision: Defined as visual acuity of 20/80 to 20/160.
- Legal Blindness: Considered as 20/200 or worse in the better eye, or having less than 120 degrees of visual field.
Visual Testing Procedure
- Steps for visual acuity testing include:
- Ensure patient is at the correct distance from the chart.
- Test OD followed by OS, using correction if available.
- Ensure the fellow eye is properly occluded.
- Correctly identifying half or more of the letters on the line is required to pass.
Adverse Conditions and Lesions
- Posterior Synechiae: Refers to iris adhesions to the lens, potentially affecting pupil assessment.
- Afferent Pupillary Defect (APD): Indicates lesions anterior to the optic chiasm.
Eye Assessment Techniques
- Cardinal Fields and Gaze: There are 6 cardinal fields of vision and 9 positions of gaze.
- Examination Steps: Adjust lighting, focus settings, and approach the eye at a 15-degree angle to assess the optic disc and surrounding retinal vessels.
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Test your knowledge on ophthalmology with these flashcards focused on eye exams, vision loss, and related drugs. Each card presents essential terms and definitions that are crucial for understanding the anatomy and functionality of the eye. Perfect for medical students and health professionals interested in this specialized field.