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Subjective refraction
The document discusses subjective refraction techniques. It begins by outlining the aims of learning about refraction and subjective refraction techniques. It then defines refraction and discusses the difference between objective and subjective refraction. Several techniques for subjective refraction are described in detail, including Jackson Cross Cylinder, fogging method, duochrome test, Worth Four Dot Test, binocular balancing, and binocular best sphere. The document provides examples and outlines the standard procedure for performing subjective refraction.
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Introduction to the speaker and context of the presentation on subjective refraction.
Outline goals including understanding refraction basics and subjective techniques.
Definition of refraction, determination of eye's refractive status through subjective means.
Explains subjective refraction principle focusing on lens combination for best visual acuity.
Overview of various subjective refraction techniques like Jackson Cross Cylinder and others.
Details on using JCC to determine cylindrical axis and power through patient feedback.
Step-by-step Fogging method for equalizing vision between both eyes in subjective refraction.
Illustration of retinoscopy process using examples to demonstrate technique variations.
Application of Duochrome test in sphere refinement through comparison of visual clarity.
Interpretation of WFDT results for assessing binocular vision and potential deviations.
Description of stenopic slit usage for finding cylinder axis and analyzing visual issues.
How the Fan and Block test is used to identify astigmatism characteristics.
Description of using Sun Burst and clock dials to determine astigmatism axes.
Application of red-green filters for diplopia testing and checking visual function.
Explains Maddox Rod use for detecting heterophoria and assessing macular function.
Describes Amsler Grid's role in detecting early signs of macular degeneration.
Details on ensuring balance between eyes after subjective refraction process.
Case study demonstrating visual acuity and correction in amblyopic conditions.
Explains the process of achieving visual balance between both eyes using prism technique.
Details on balancing vision clarity through methods of alternating eye occlusion.
Methodology for determining maximum binocular acuity through spherical endpoint adjustments.
Overview of near refraction measures, including suggested additions based on age.
Stepwise explanation of procedural aspects necessary for performing subjective refraction.
Listing of reference materials and resources for comprehensive understanding of optometry.
Conclusion of the presentation with invitation for participant questions.
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Subjective refraction
- 1. Subjective Refraction Md.Azizul Islam JuniorOptometrist(Oculoplasty) Ispahani Islamia Eye Institute & Hospital IIEI&H IIEI&H e-mail: [email protected] twiter: @ajijulislam513 , Cell:01724-310486
- 2. Aims of Today,sClass… To know…… Basic idea about refraction. Able to done subjective refraction confidently. To know Subjective refraction techniques. The sequence of the subjective refraction. Binocular Refraction:- 1.Binocular balancing 2.Binocular best Vision sphere IIEI&H
- 3. What is Refraction? Determinationof the refractive status(prescription) of the eye. OBJECTIVE Retinoscopy SUBJECTIVE Subjective Refraction Subjective Refraction To determine by subjective means the combination of spherical and cylindrical lenses necessary to to provide best visual acuity. (with accommodation relaxed) IIEI&H
- 4. Subjective determinationof the combination of sphere and cylindrical lenses that artificially places the far point of Each Eye of patient at infinity. Maximum PLUS, minimum minus. Take into account vertex distance Especially for high prescription This is the combination of lenses that provides best VA with accommodation relaxed Principle of subjective refraction IIEI&H
- 5. Jackson CrossCylinder Fogging Method Duochrome Test WFDT(Worth Four Dot Test) Stenopic Slit Ast:fun Sun brust Dial/clock dial Red Green filter Maddox Rod Binocular Balancing Binocular Best Vision Sphere Subjective refraction techniques. IIEI&H
- 6. Jackson Cross Cylinder JCCused to find used to determine the cylindrical axis and the cylindrical power for the patient. In a cross-cylinder the axes are 45 and 135 deggre. Patient directed to observe a round target. Patient asked: “Is view one rounder, sharper, clearer or view two?” We turn the axis 5 degrees towards it and the opposite if the patient wears a negative one instead. We repeat the process until the patient doesn’t refer any difference in his vision. This is the correct axis. IIEI&H
- 7. Fogging Method Used onlywhen VA is EQUAL in both eyes 1. Fog both eyes with + 0.75DS 2. Direct patient to view 3 lines above best VA 3. Alternately occlude each eye for ~0.5 secs each while asking patient: “ Which eye sees clearer/sharper?” 4. Add +0.25DS to the better eye 5. Repeat step 3 and 4 until both eye’s vision is equalised 6. Slowly reduce fog until best VA is reached 7.A plus (a mild plus) is used to relax eye focusing muscle completely in distant viewing. The eye is no longer accommodated with such a lens for distant vision. Tightened focusing muscle must be completely relaxed in order to see clearly. IIEI&H
- 8. Example: Suppose you areperforming retinoscopy on a +3.00 D hyperopic OU for the first time, and he does not have an old Rx that would give you a clue. Using even +1.50 or the "R" lens would not get you close to fogging the fellow eye. Conversely, if the eyes where - 3.00 D OU, the "R" lens over the fellow eye would be serious overkill. IIEI&H
- 9. Duochrome Test Ask thepatient: "Are the rings/letters/dots clearer and backer on the red or on the green, or are they the same?” If the rings on the green are clearer, add plus power needed to obtain balance. If the rings on the red look clearer, add minus power obtain balance. If more than +/- 0.50 DS is required to balance, this usually indicated the duochrome test is not reliable for this patient and should be ignored. N.B:A Duochrome test is a test commonly used to refine the final sphere in refraction, which makes use of the chromatic aberration of the eye. IIEI&H
- 10. WFDT(Worth Four DotTest) THE PATIENT SEES ALL FOUR DOTS : -Normal binocular response with no manifest deviation. THE PATIENT SEES FIVE DOTS: - uncrossed diplopia with esotropia, red dots appear to the right. - crossed diplopia with exotropia, red dots appear to the left of the green dots. IF THE PATIENTS SEES THREE GREEN DOTS, SUPPRESSION OF THE RIGHT EYE IF THE PATIENT SEES TWO RED DOTS, SUPPRESION OF THE LEFT EYE IIEI&H
- 11. Stenopic Slit The stenopicslit found in all the trial sets is 1-2 mm by 15-35 mm in size. It splits an opaque disc into two halves. It is useful in finding out the axis of the cylinder . Black opaque disc with vertical / horizontal straight slit at centre To differentiate causes of haloes Fincham’s test IIEI&H
- 12. Astigmatism fan The Fanand Block test is used to determine the axis and magnitude of astigmatism. The fan is used to determine the presence of any astigmatism and its principal axes. IIEI&H
- 13. Sun Brust Dial/Clockdial Clock dial Sun Brust Dial The sun brust dial and clock dial test is also used to determine the axis and magnitude of astigmatism. Those are used to determine the presence of any astigmatism and its principal axes. IIEI&H
- 14. Red-Green filters Red placedin front of right eye Green glass in front of left eye Used for diplopia charting To test binocular vision in Worth’s four dot test For malingering test. Red-Green filters also used to cheek colour sense of the retina before cat Sx. IIEI&H
- 15. Maddox Rod 4-5 cylindersof red glass prisms. Fused side by side in a round disc frame. May give the effect given by…. Deeply grooved red glasses(mad groove). To detect heterophoria. As it dissociates two retinal images. As macular function test. IIEI&H
- 16. The AmslerGrid looks like graph paper, with dark lines forming a square grid. Some versions have white lines on a dark background. One of the first signs of macular degeneration can be wavy, broken or distorted lines OR a blurred or missing area of vision. The Amsler Grid can help you spot these early. Early detection of wet AMD is critical because laser treatment, when indicated, is most successful when performed before damage occurs. Since dry AMD can lead to development of wet AMD. Amsler Grid IIEI&H
- 17. Binocular Balancing The binocularbalance test occurs after a monocular subjective refraction to ensure that accomodation is balanced in the two eyes. There is no need to perform this test if the patient is monocular, or if they have no accomodation (i.e. patients over the age of 60 or pseudophakic). There are several techniques that have been described previous. which effectively uses the plus/minus technique of best vision sphere determination under binocular conditions after first fogging rather than occluding the non-tested eye. Methods for binocular balancing Prism Dissociated Blur Balance Alternate Occlusion IIEI&H
- 18. Under binocular conditions,the amblyopic eyes accept more of the indicated correction and obtains better acuity VA in RE 6/6 VA in LE 5/60 On retinoscopy: RE +1.00 DS LE +4.00 DS VA in LE with +4.00 DS = 6/60 on monocular subjective refraction LE: 6/24 with +2.50 DS on binocular condition LE: 6/18 with +3.50 DS Example: IIEI&H
- 19. Prism dissociated blurbalance RE – 3 ∆ Base Down LE – 3 ∆ Base UpTwo charts will be seen separated vertically If vision in both eyes to 6/12, on to sphero/cylinder lenses found monocularly; - assuming eyes capable of 6/6 acuity If one eye has reduced VA; -A row of letters at least two rows larger than that of the power eye of best acuity IIEI&H
- 20. Alternate occlusion technique Target:Smallest acuity letters patient can read through the spherocylindrical correction Alternately occlude the patient’s eye with cover paddle . If the images equally clear- balance is correct. If not, two options:- 1.add plus sphere in +0.25 DS steps before the eye with better image till both the images are equally blurred 2.add minus sphere in 0.25 DS steps before the eye with poorer image till both images are equally clear Finally to confirm, add +0.25 DS before each eye. If the balance is correct BE will be equally blurred IIEI&H
- 21. Binocular Best Sphere Theeyes are simultaneously fogged and then unfogged until maximum binocular acuity is attained The spherical endpoints are the maximum plus or minimum minus power providing maximum binocular visual acuity These endpoints are usually about +0.50 DS more plus or less minus than those found monocularly IIEI&H
- 22. Subjective refraction atnear Near refraction refers to the measurement of the refractive state when the patient is fixating at near point. Useful in conditions that significantly alter the refFinding the Near Addition.Age (in Years) Estimated Add (in D) refractive error when patient fixates at near.. Age add 38 -40 + 0.75 to + 1.00DSP 40 -43 + 1.00 to + 1.25 DSP 43 -45 + 1.25 to + 1.50 DSP 45 - 47 + 1.50 to + 1.75 DSP 47 – 50 + 1.75 to + 2.00 DSP 50 – 52 +2.00 to + 2.25 DSP 52-55 +2.25 to +2.50 DSP 55-Above +2.50 to +3.00DSP N.B: Needs +3.00 DSP Near Add for Aphakia patient. IIEI&H
- 23. History Working distance Fixation target Patientinstructions Record Visual acuity (VA) distance Unaided, Added, Pinhole test. Starting point Locating principal meridian Procedure for astigmatism Record Near vision + Near correction Messurement IPD Prescription and Advice PROCEDURE of SUBJECTIVE REFRACTION IIEI&H
- 24. References Examination Protocol(Ophthalmology) Clinical Procedures in Optometry A Hand Book of Basic Optometry & Refraction Essentials of Ophthalmology , Basak 5th Edition. Internet (Google) IIEI&H
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