Portland Community College | Portland, Oregon

Upon successful completion students should be able to:
1. Use an understanding of advanced optical principles to assist low vision patients in a clinical setting.
2. Apply an understanding of visual perception when assessing patients with visual problems.
3. Use an understanding of contact lens principles to educate patients in a clinical setting in the care and use of contact lens.

The material in this course will be presented in lecture and lab format. Other methods may be employed such as discussion, recitation, research papers and small group work. Guest speakers and field trips may be utilized by the instructor as a means of assisting the student in mastering competency.

Student progress is evaluated by projects, reports, quizzes, lab modules, midterm test and a final examination based on specific course objectives. Student’s grades will be determined by demonstrated course competency.

COURSE CONTENT (Themes, Concepts, Issues) and SKILLS:

1. Low Vision
2. Visual Perception of Size and Distance
3. Visual Perception of Movement
4. Visual Perception of Color
5. How lens design effects visual perception
6. Vertex Distance
7. Illumination watts, foot candle, photometers
8. Optics of contact lens tear film, vertex, power, LARS, SAM/FAP
9. Introduce principles of retinoscopy and refraction

COMPETENCIES AND SKILLS

VISION

• Explain the difference between learned versus innate visual perception.
• Explain how the brain organizes and adapts to stimulus.
• Identify brain functions that take place as stimuli are received.
• Explain the organization principles that interpretation of visual stimulus are based upon, including figure ground, closure, proximity, similarity, perceptual sets, constancy.
• Explain how the brain can be fooled by visual illusions.
• Explain some of the problems cause by putting corrective lenses in front of the eyes including aniseikonia and diplopia.
• Explain how magnification is related to dioptric power and in what way magnification increases relative size.
• Describe different types of hand held and stand magnifiers and how they can be used to help some low vision patients including:

• Importance of increased lighting for those with low vision
• Different types of spectacle aids for low vision.
• Advantages and disadvantages of projection magnifiers for low vision patients.
   

REFRACTION

• Define basic terms used in the geometry of refraction including: parallel, intersection, perpendicular, normal, diverging/converging, angle of incidence, angle of refraction.
• Relate index of refraction to refractive power of ophthalmic lens material.
   

OPTICS OF SIMPLE PLUS AND MINUS LENSES

• Describe, define and/or (if appropriate) locate the following terms:

• Focal lengths
• Vertex point
• Optical center
• Axis line
• Object/image distance
• Image characteristics
• Virtual/real
• Magnified/same minified

• Describe nature and characteristics of images formed by negative lenses when object is at any distance from the lens.
• Describe nature and characteristics of images formed by positive lenses when object is at: infinity, ½, 1, 2, 3 times the focal length of the lens.
   

VERTEX POWER CHANGES AND COMPENSATION FOR POSITIONAL CHANGES

• Define vertex distance.
• State at what powers or conditions, positional compensation for Rx must be considered.
• State usual refraction distance.
• Discuss rule about lenses losing plus power as vertex distance increases.
• Use a chart to find effective power or new Rx.
• Use a formula to find effective power or new Rx.

CONTACT LENSES

• Measurement of contact lenses.
• Patient instruction for care and use of contact lens.
• Patient counsel.
• Fitting theory of both soft and RGP contact lens.

SLIT LAMP BIOMICROSCOPY

• Describe two major styles of slit lamps.
• Define "coaxial" as it relates to the slit lamp.
• Differentiate "magnification" vs. "illumination" in isolating pathology with the slit lamp.
• Describe the procedure for properly setting each eyepiece of the slit lamp microscope.
• List 6 "direct" and 6 "indirect" forms of illumination with the slit lamp.
• Describe the use and technique for each of the following forms of illumination: diffuse, parallel piped, optical sectioning, tangential, conical beam, specular reflection, proximal illumination, sclerotic scatter, direct retro illumination from the iris, indirect retro illumination from the iris, retro illumination from the fundus, and iris transillumination.
• List the different filters available on the slit lamp and their usage.
• Describe the vital dyes and their usage when used with the slit lamp including: Fluorescein, rose Bengal and lissamine green.
• Describe when the Seidel test is used and how it is performed.
• Describe accessory lenses available to use with the slit lamp microscope; why and how they are used.

• Define Slit lamp photography
• Define Anterior segment photography
• Define External photography
• Define Endothelial cell counts
• Describe Corneal topography

RETINOSCOPY

• Discuss the principles and techniques of retinoscopy.
• List at least 3 types of patients for whom retinoscopy is critical because refractometry cannot be performed.
• Describe the proper set up with both phoropter and trial frames for performing retinoscopy.
• Describe the reasons for "fogging" the fellow eye and having the fellow eye unoccluded during retinoscopy.
• Describe proper sleeve position for both Copeland and Welsh Allyn types of retinoscopes.
• Describe the purpose of using a "working lens" or subtracting "working distance" from the patient’s retinoscopic findings.
• List the steps performed when retinoscoping in plus cylinder.
• Explain the use of the "double sphere" method in retinoscopy.
• List the types of motion observed in patients with emmetropia, myopia, hyperopia and astigmatism.
• List the types of lenses used to neutralize motion in myopes, hyperopes and astigmats.
• Describe a method of confirming that neutrality has been achieved in retinoscopy.
• Give estimated spherical refractive errors for patients with visual acuities of: 20/80, 20/200, 20/400, worse than 20/400.
• Explain how keratometric findings can help in finding proper correction of axis in retinoscopy.
• Describe a retinoscopic reflex in patients with high refractive errors
• Define refractometry, differentiate from refraction.
• Define emmetropia, ametropia, hyperopia, myopia and astigmatism.
• Describe symptoms of myopes, hyperopes and astigmats.
• Describe the steps in refractometry
• Identify all the working parts of a phoropter.
• List the 5 main steps in refractometry.
• List at least 5 rules to use in refractometry.
• Describe the correct usage of the Jackson Cross cylinder in testing both cylinder axis and power (in plus cylinder).
• Describe trial frames and loose lenses and define how refractometry using these is different than with a phoropter.
• Define vertex distance and explain when and how it is measured in performing refractometry