Ophthalmic Refraction Techniques

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Questions and Answers

What should be done if the cylinder axis has a DC of 1.00 or less?

  • Move the axis 10Ëš
  • Leave the axis unchanged
  • Move the axis 20Ëš (correct)
  • Move the axis 30Ëš

What is the correct endpoint when refining the cylindrical axis?

  • When both choices look the same (correct)
  • When both choices appear different
  • When one choice is clearer than the other
  • When both choices seem brighter

If a patient reports that letters look better when the red dots are parallel to the axis, what adjustment should be made?

  • Remove -0.25 DC
  • Decrease the sphere power
  • Add +0.25 DC
  • Add -0.25 DC (correct)

How much sphere adjustment should be made for every two clicks of cylindrical power added?

<p>Add +0.25 D sphere (A)</p> Signup and view all the answers

What is the next step after refining cylinder axis?

<p>Determine the Cylinder Power (A)</p> Signup and view all the answers

When refining cylinder power, how should one adjust if letters look better when white dots are parallel to the axis?

<p>Remove -0.25 DC (D)</p> Signup and view all the answers

What precedes the determination of binocular balance in the sequence of refraction?

<p>JCC to Refine Sphere Power (C)</p> Signup and view all the answers

What must be done to maintain the circle of least confusion when adding cylindrical power?

<p>Increase sphere power (D)</p> Signup and view all the answers

What should a patient be able to read to indicate improvement after adding -0.50 DS?

<p>20/20 line (D)</p> Signup and view all the answers

What occurs when a patient is over-minused during refraction?

<p>Letters appear smaller (C)</p> Signup and view all the answers

If +0.25 DS does not worsen the letters, what is the next step?

<p>Try more plus power (C)</p> Signup and view all the answers

What is the first step in the Manifest Refraction Sequence?

<p>Determine Sphere Power Starting Point (C)</p> Signup and view all the answers

What is the purpose of Binocular Balance in subjective refraction?

<p>To balance out visual stimulus to accommodate (C)</p> Signup and view all the answers

What does a patient need to demonstrate to receive extra minus during refraction?

<p>Improved visual acuity (B)</p> Signup and view all the answers

What principle should be followed to ensure correct refraction results?

<p>Avoiding over-minusing (C)</p> Signup and view all the answers

What should be the approach if a patient presents unequal acuity in each eye?

<p>Refine cylinder axis and power (D)</p> Signup and view all the answers

What does the midpoint of break indicate in the context of vertical phoria interpretation?

<p>The presence of hypophoria or hyperphoria (A)</p> Signup and view all the answers

In the provided example, what is the effective way to determine the midpoint when given different supravergence and infravergence readings?

<p>Subtract the smaller range from the larger range and then divide by two (B)</p> Signup and view all the answers

What does the notation '4pd BU/2pd BU' signify in the vertical vergence findings?

<p>The degree of infravergence related to the right eye (C)</p> Signup and view all the answers

What is the purpose of introducing BU prism during infravergence testing?

<p>To assess recovery from vertical deviation (C)</p> Signup and view all the answers

How should the horizontal vergence ranges be set according to the guidelines?

<p>To calibrate both prisms to zero (C)</p> Signup and view all the answers

If a patient has Right Supravergence = 3pd BD and Right Infravergence = 5pd BU, what is the midpoint of break?

<p>1pd BU (D)</p> Signup and view all the answers

Asymmetric supra and infra vergence findings can confirm what condition?

<p>A vertical phoria (A)</p> Signup and view all the answers

What is the primary goal when refining sphere power during retinoscopy?

<p>To adjust the location of the Circle of Least Confusion (C)</p> Signup and view all the answers

What does a reading of '1pd BU OD' suggest in regards to patient's binocular vision?

<p>Weakness in vertical muscle function (C)</p> Signup and view all the answers

What should be done to the room lighting during a visual acuity check post-retinoscopy?

<p>Keep it dark or very dim (B)</p> Signup and view all the answers

What is the correct approach if a patient’s monocular acuity is 20/20 during retinoscopy?

<p>Add plus sphere in 0.50 DS steps until the patient loses letters (C)</p> Signup and view all the answers

If the monocular acuity is between 20/25 and 20/30, what should be added during the examination?

<p>Plus 0.50 DS steps (C)</p> Signup and view all the answers

What action is advised if a patient reports that their vision looks worse but can still read the same size letters?

<p>Have the patient re-read the lowest line possible (B)</p> Signup and view all the answers

What should be done if the patient loses some letters after the first plus DS step?

<p>Remove the last plus DS step and try minus DS (D)</p> Signup and view all the answers

What is the importance of occluding one eye during the visual acuity test?

<p>To ensure only one eye is assessed at a time (C)</p> Signup and view all the answers

What measurement should be taken if a patient cannot read the lowest line displayed?

<p>Document the highest line they read and conclude (B)</p> Signup and view all the answers

What is the primary goal of manifest refraction?

<p>To create artificial emmetropia using corrective lenses (C)</p> Signup and view all the answers

Which sequence is proper for the monocular subjective refraction process?

<p>Determine Sphere Power, JCC to Refine Cylinder Axis, JCC to Refine Cylinder Power (A)</p> Signup and view all the answers

In retinoscopy, what does an increase in positive sphere indicate?

<p>The patient experiences blur (C)</p> Signup and view all the answers

What is the purpose of using a cobalt blue filter during examination?

<p>To illuminate corneal defects with vital dye (C)</p> Signup and view all the answers

What happens when a patient cannot relax accommodation during a vision exam?

<p>The retinal image may be blurred (B)</p> Signup and view all the answers

What is the function of the 'Circle of Least Confusion' in refraction?

<p>To ensure light focuses on the retina (D)</p> Signup and view all the answers

What is a typical initial step in the manifest refraction sequence?

<p>Determine Sphere Power Starting Point (A)</p> Signup and view all the answers

Which option is considered an auxiliary feature to improve visibility in eye examinations?

<p>Red free filter (D)</p> Signup and view all the answers

When using the JCC in the refraction process, what is the main objective?

<p>To refine the cylinder axis and power (A)</p> Signup and view all the answers

What effect does a negative sphere power have on visual acuity when over the distance BVA?

<p>It can create additional blur (C)</p> Signup and view all the answers

What symptom may indicate that a patient has been over-minused?

<p>Presence of blur on BI vergence ranges at distance (A)</p> Signup and view all the answers

Which near target chart is used for measuring near acuity?

<p>Reduced Snellen (20/50 to 20/20) (C)</p> Signup and view all the answers

What is the main use of the Cross cylinder grid?

<p>Conduct fused cross cylinder test for near add determination (C)</p> Signup and view all the answers

What indicates that a patient's NRA finding is greater than normal?

<p>Greater than +2.50 D (C)</p> Signup and view all the answers

What is NOT a reliable measure of visual acuity?

<p>Reading chart (20/60 to 20/20) (A)</p> Signup and view all the answers

What is the purpose of the sunburst dial in optometry?

<p>Determine cylinder axis (D)</p> Signup and view all the answers

The horizontal line of words is used to evaluate which of the following?

<p>Break and recovery of vertical vergence amplitudes (D)</p> Signup and view all the answers

What condition is the Cross Cylinder grid NOT reliable for?

<p>Presbyopia evaluation (D)</p> Signup and view all the answers

Which near target chart is specifically focused on measuring accuracy of accommodation?

<p>Cross cylinder grid (C)</p> Signup and view all the answers

What is the primary function of NRA/PRA in optometry?

<p>Determine the amount of near add required (D)</p> Signup and view all the answers

Flashcards

Discoloration

A change in the color of a part of the eye or skin.

Cobalt Blue Filter

A tool used to enhance visibility of corneal defects.

Sodium Fluorescein

A vital dye used to illuminate eye defects.

Manifest Refraction

A method to determine the eye's need for corrective lenses.

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Emmetropia

The condition where light focuses perfectly on the retina.

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Monocular Subjective Refraction

Testing one eye's refraction independently.

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JCC (Jackson Cross Cylinder)

A test to refine cylinder axis and power in refraction.

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Circle of Least Confusion

Point where vision is clearest during astigmatism testing.

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Interval of Sturm

The distance between two lines of focus in astigmatism.

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Binocular Balance

Adjusting vision in both eyes for even clarity.

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JCC

A technique to refine cylinder axis and power in vision correction.

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Refine Cyl Axis

Adjusting the cylinder axis using the JCC method to achieve optimal vision clarity.

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Chase the red dots

A method to determine the correct axis by seeing which orientation looks clearer.

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DC (Diopter Change)

Measurement of the amount of lens power change needed to correct vision.

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Endpoint

The point in testing when no further improvements can be noticed by the patient.

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Sphere Power Adjustment

Changing sphere power to maintain clarity when modifying cylinder power.

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Dioptic midpoint

The ideal point on the retina where optical clarity is achieved.

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Retinoscopy

A technique used to determine eye prescriptions by evaluating the reflection of light off the retina.

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Monocular acuity

The clarity or sharpness of vision in one eye.

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VA after ret

Visual acuity measured after retinoscopy to determine prescription success.

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Sphere power

The strength of a lens needed to correct spherical refractive errors.

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Plus sphere in DS steps

Incremental adjustments made with positive spherical lenses during vision testing.

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Supravergence

A vertical eye movement where one eye moves upward relative to the other.

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Infravergence

A vertical eye movement where one eye moves downward relative to the other.

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Vertical Phoria

A misalignment of the eyes in the vertical direction, often revealing under or overaction of eye muscles.

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Midpoint of Break

The point at which there is equal tilt in eye testing, suggestive of a specific phoria type and direction.

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Right Hypophoria

A condition where the right eye is positioned lower than the left eye when the patient is looking straight ahead.

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Asymmetric Vergence

Unequal eye movements when tested for both supravergence and infravergence, indicating possible phoria issues.

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Prism Direction Assignment

Assigning prism based on the greater range in eye movement testing to correct misalignments.

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Vergence Ranges Review

Assessment of horizontal and vertical eye movements to determine visual efficiency and alignment.

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Over-Minusing Indicators

Blur in BI vergence ranges at distance and NRA > +2.50 D.

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Reading Chart #1

Used for visual acuity; not precise, speed decreases nearing threshold.

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Reduced Snellen Chart

Measures near acuity with sizes from 20/50 to 20/20.

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Cross Cylinder Grid

Used for FCC/BCC tests; not reliable for non-presbyopes.

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Vertical Vergence Amplitudes

Measured with horizontal lines; assesses break and recovery.

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NRA/PRA Chart

Single row chart used in refraction tests; specifics to be covered later.

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Sunburst Dial

Determines cylinder axis for irregular astigmatism and mild keratoconus.

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Clock Dial Example

A method where patients identify clearer lines for vision assessments.

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Presbyopia Indicators

Characteristics indicating difficulty adjusting focus at near distances.

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Monocular Subjective Sphere

A vision test method for each eye separately to refine lens power.

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Amblyopia

A condition where vision in one eye is reduced because it is not used normally during early childhood development.

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Overminus

Providing excessive minus lens power, leading to smaller and less clear letters in a vision test.

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Subjective Refraction

A method of determining eyeglass prescriptions based on patient feedback and preferences.

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Visual Acuity (VA)

The clarity or sharpness of vision, often tested using an eye chart.

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Study Notes

Optometry II - Opto 5272

  • Course introduction and spherocylindrical retinoscopy were covered on January 3, 2024
  • Lucy Kehinde Darnell, OD, PhD, FAAO was the instructor

Refractive Error Review

  • Spherical refractive error possibilities include myopia, emmetropia, and hyperopia.
  • Myopia: The eye is longer than it should be, causing light rays to focus in front of the retina.
  • Emmetropia: The eye is the correct shape, so light rays focus correctly on the retina.
  • Hyperopia: The eye is shorter than it should be, causing light rays to focus behind the retina.
  • Spherocylindrical classifications include simple astigmatism, compound astigmatism, and mixed astigmatism.
  • Simple astigmatism: One emmetropic meridian, one hyperopic or myopic meridian
  • Compound astigmatism: Both principal meridians are hyperopic or myopic.
  • Mixed astigmatism: One hyperopic meridian and one myopic meridian.

Spherocylindrical Retinoscopy Steps

  • Align Purkinje images
  • Scope all meridians and determine the two major (principal) meridians; get rid of all motion.
  • Neutralize the MOST PLUS (least minus) meridian FIRST.
  • Set the cyl axis of the phoropter and scope the MOST MINUS (least plus) meridian.
  • Add minus cylinder power until you have neutralized the against motion
  • Take out your working distance

Astigmatism Classifications

  • With-the-rule: meridian of greatest refractive power is within 30° of vertical
  • Against-the-rule: meridian of greatest refractive power is within 30° of horizontal
  • Oblique: meridian of greatest refractive power is oblique with respect to the vertical or horizontal meridians

Astigmatism Classifications (cont.)

  • Symmetrical astigmatism: weakest/strongest meridians of both eyes sum up to 180°.
    • Homologous/heterologous symmetrical
  • Asymmetrical astigmatism: weakest/strongest meridians of both eyes do not sum up to 180°.
    • Homonymous/heteronymous

Astigmatism Classifications (cont.)

  • Total manifest astigmatism: measured in subjective refraction.
  • Corneal astigmatism: results from variation in refractive power of the cornea.
  • Internal/residual/physiological astigmatism: in posterior cornea or crystalline lens (approximately 0.50 DC).

Lecture 2 - Retinoscopy on a Patient & Direct Ophthalmoscopy

  • Review of spherocylindrical retinoscopy steps
  • Patient set-up: room lights are off or very dim, patient must be able to view distant target with the unscoped eye, block the eye being scoped with your head.
  • Patient's accommodation: relaxed using cycloplegic eye drops or fogging
  • Additional plus beyond patient's refractive error
  • Oblique observation
  • Retinoscopy on a patient steps: Patient instructions, fog left eye, position yourself, neutralize OD, take out lenses, and document

Direct Ophthalmoscopy

  • Advantages: Easier to learn, high magnification, allows for evaluation of structures in front of the retina, no image reversal.
  • Disadvantages: Limited field of view, monocular procedure, dim image, close working distance.
  • Procedure: Reduce ambient light, grasp like microphone, give patient fixation point, set power wheel, shine light into pupil from 25 cm slightly temporal. Examine optical media, take out working lenses, record
  • Auxiliary features: slit lamp, half light (hemispot), cobalt blue, red free, grid, polarized filter
  • Further instructions on how to examine the optic disc, vasculature, and macula

Getting started with EyeSi Simulator

  • Email from VRmNet Web Portal ([email protected])
  • Complete online orientation before Lab 2
  • Set a new password (keep it simple!)

Lecture 3 - Subjective Refraction Part 1 - Monocular Subjective

  • Manifest refraction sequence
    • JCC
    • determines sphere power starting point
    • refines cylinder axis and power
    • followed by monocular subjective sphere, binocular balance, and binocular subjective sphere
  • Goal of manifest refraction: create artificial emmetropia using corrective lenses
  • Using max plus (least minus) for best visual acuity.

Lecture 3 - Subjective Refraction Part 2 - Binocular Subjective

  • Binocular subjective: final sphere determination for patient's prescription.
    • Procedure is the same as the monocular subjective, except both eyes are open at the same time.
  • Binocular balance, balancing out stimulus to accommodate for the eyes.
  • Avoiding accommodation during refraction
    • cycloplegic refraction (Tropicamide/Cyclopentolate)
    • binocular refraction technique
  • Techniques:
    • Septum
    • Fogging
    • Polarization (Vectographic Slide, Borish Card)
  • Important: Always change both lenses together.

Lecture 4 - Subjective Refraction Part 2 - Binocular Balance & Binocular Subjective

  • Binocular Balance: balancing out stimulus to accommodate for the eyes.
  • Binocular Balance Techniques: Prism dissociated balance, Vectographic Balance
  • Procedure: display target and prisms, instruct patient, document
  • Why worry/importance: reduced stereo acuity, central suppression, asthenopia, and a big imbalance.
  • Important: Avoid over-minusing

Near Testing

  • Follow the same procedures for near testing, but the IPD is set for near and the chart is at 40 cm rather than distance.
  • Use of charts for near testing are included.

Near Targets and Refractive Error Classifications

  • Chart #1: Reading chart (20/60 to 20/20)
  • Chart #2: Reduced Snellen charts (20/50 to 20/20)
  • Chart #3: Cross-cylinder grid (Fused cross cylinders) BCC
  • Chart #4: Horizontal lines of words (Horizontal vergence ranges)
  • Chart #5: Single row of 20/20 letters (NRA/PRA)
  • Chart #6: Sunburst dial (determining cylinder axis)
  • Chart #7: Reading chart (20/200 to 20/80)
  • Chart #8: Reduced Snellen (20/200 to 20/60)
  • Chart #9: Reduced Snellen (20/200 to 20/20)
  • Chart #10: Vertical column of words (Horizontal vergence ranges)
  • Chart #11: 7-line block of 20/20 letters (Horizontal and Vertical Phoria)
  • Chart #12: Trifocal charts

Refractive Status Classifications

  • Emmetropia
  • Ametropia
  • Hypermetropia/Hyperopia
  • Types include, Simple, Pathological, and examples such as Microphthalmos, Aphakia, and Ectopia lentis.
  • Classifications for Low, Moderate, and High, based on diopters

Myopia

  • Types of Myopia include, Low, Moderate, and High, based on diopters.
  • Pathological: Axial elongation.
  • Associated diseases include Retinal tears, Posterior staphyloma, and Macular hole.

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