A Checklist for Managing Spectacle Lens Complaints. Presented By: Raymond P. Dennis, M.A. (Ed.) Middlesex Community. Patient Complaints

Transcription

1 SPEAKER FINANCIAL DISCLOSURE STATEMENT Raymond P. Dennis has occasionally received honoraria from Essilor of America to present generic continuing education presentations similar to this one. He is a member of the Speaker s Bureau for Essilor of America. A Checklist for Managing Spectacle Lens Complaints Presented By: Raymond P. Dennis, M.A. (Ed.) Middlesex Community Patient Complaints Generally, complaints fall into two distinctly different categories: Complaints that are Optical in Nature affecting the way the patient sees Complaints that are related to the fit or physical comfort Why People Complain 1. Genuine Vision Problems 2. Adaptive Issues 3. Cosmetic Concerns 4. Other Causes of Complaint Getting Started Get a clear picture of what is bothering the patient Is it optical or physical? Problem Solving Requires That You Ask Questions to Determine the Problem Requires Your Complete Attention to the Client s Response Clients Don t Like to be Ignored or Patronized 1

2 Problem Solving: Anticipate - Learn to Solve Problems Before They Happen Learn how to Diagnose a Problem Set up a Logical Order of Steps to Find a Solution Learn how to solve a Problem That Has Already Occurred Solving Problems Before Anticipate Problems With Unusual Rx. s They (Like Vertex Happen Distance and Prism Problems in Strong Rx. s) Ask the Client Questions About Working Distance(s) & Where they Like to Position Their Eyeglasses Learn to Visualize the Finished Product Help the Client to Visualize it Learning Requires the to Use Diagnose of Logic and a Analysis Problem Always Consider First the Most Obvious (the glasses were made wrong) Ask if the Problem is Physical (fit), or Visual (Rx. Or fit) Remember, Sometimes the Problem is That the Client The Is Bad Angry For Business or Irate Client Is Difficult to Satisfy Is Important to the Company s Success Will Tell 11 People About their Experience Each of the Eleven Will tell Five More The Angry or Irate Client Learn How to Defuse the Situation Calm Them Isolate Them Show Your Concern Standards for the Optical Industry ANSI Z Prescription Ophthalmic Lenses ANSI Z Safety Eyewear Solve Their Problem 2

3 Tolerances on Prism Reference Point Location In& all Prismatic cases the tolerances Power shown apply to lenses with and without prescribed prismatic power. A Prism Reference Point (PRP) placement error of +/- 1.0 mm in any direction is permissible. Tolerances on Prism Reference Point Location Prismatic imbalance from & Prismatic Power processing between mounted lenses in the vertical direction shall not exceed 0.33 prism diopters. A variation of 1.0 mm in vertical level is permissible. (ANSI Z80.1) Tolerances on Prism Reference Point Location & Prismatic Power Prismatic imbalance from processing between mounted lenses in the horizontal direction shall not exceed 0.67 prism diopters. A variation of +/- 2.5 mm from the specified distance interpupillary distance is permissible. (ANSI Z80.1) Meridian of Highest Power From 0.00 to +/ Above +/ Refractive Power Tolerance Cylinder Cylinder Cylinder 0.00 Diopters 2.00 Diopters Tolerance 2.00 Diopters 4.50 Diopters 4.50 Diopters +/ / / /- 4% +/- 2% +/ / /- 4% Tolerances on Cylinder Axis > 0.00 D D. > 0.25 D D. > 0.50 D D. > 0.75 D D. > 1.50 D. ±14 ±7 ±5 ±3 ±2 Tolerance on Addition Power D > D ±0.12 D ±0.18 D 3

4 Tolerances on Segment Vertical and Segment Fitting Cross ±1.0 mm Each Height Location Vertical Segment Difference Horizontal Segment Location 1.0 mm Difference ±2.5 mm Total The distance between the geometric centers Segment of the segments Horizontal in the mounted pair shall be within +/- 2.5 Location mm of the specified near interpupillary distance. The inset in both lenses shall appear symmetrical and balanced unless monocular insets are specified. Progressives are fit with reference to the distance PD and are exempt from this requirement. Segment Tilt The tilt of horizontal axis of a segment with a straight-edged top shall be less than 2 degrees. Segment Vertical Location The segment height shall match within +/ mm of specification. In progressive addition lenses the fitting cross height shall be within 1.00 mm of specification. The difference between the segment height or fitting cross height in the mounted pair shall not exceed 1.00 mm. Segment Size Tolerances The segment dimensions for Multifocals (width, depth, intermediate depth) shall not deviate by more than (+ or -) 0.5 mm. The difference between the segment measurements in the mounted pair shall not exceed 0.7 mm. Tolerance The center on thickness Center shall Thickness be measured at the Prism Reference Point of the convex surface and normal to the surface. It shall not deviate from the nominal value by more than +/- 0.3 mm. Note: the nominal thickness of a lens may be specified by the prescriber or be the subject of agreement between prescriber and supplier. (ANSI Z80.1) 4

5 Base Curve Requirements When specified, the base curve shall be supplied within +/ D. The base curve shall be given using an assumed index or refraction of (ANSI Z80.1) Tolerances on PRP Location and Prismatic Tolerances Power apply to lenses with and without prescribed prismatic power A PRP placement error of +/ mm in any direction is permissible (ANSI Z80.1) Visual Problems: Use or at Near? Logic Is the Problem in the Distance, Is it Both Eyes? Right, or Left (You may have to Actually Test This Is it Constant, or Intermittent? It May be Edema Related or a Drug Side Effect Visual Optical Problems Applying ANSI Standards is one way of ensuring that the patient receives a pair of glasses that is an appropriate application of the requirements specified by the doctor as a result of his/her refraction Is it a Problem With Working Undercorrected Distance Rx. Doctor May Have Purposely Undercorrected A Hyperope Will Need to Use Accommodation for Distance A Myope Cannot Compensate for This May Complain of Eyestrain or Headaches Refer for Re-check Overcorrected Distance Dr. s Error Hyperope Cannot Compensate Myope Can, by Using Accommodation May Cause Eyestrain or Headaches Refer for Re-check 5

6 Will Undercorrected Need to Hold Reading Near Material at a Longer Working Distance Can be More of a Problem for Older Clients With Little Remaining Accommodative Ability May Cause Eyestrain or Headaches Will Overcorrected Necessitate Holding Near Reading Material Too Close More of a Problem For High Add Powers Reduces Chances of Seeing at Intermediate May Causes Eyestrain or Headaches Wrong Rx. - We Blew It! Be Sure to Know and Use Your A.N.S.I. Standards Be Careful When Verifying Remember, The Quality of Work Done in any Optical Shop is Controlled by One Person.. The Person Checking the Work Wrong Rx. - The Dr. Blew Dr. Wrote the Wrong Sign It! Dr. Didn t Ask About Working Distance Illegible Writing on Rx. Didn t Record Vertex on High Rx. Tactfully Request a Re-check The determination of add power is a Add critical Power factor in satisfying and Working the near and intermediate visual needs of Distance every presbyopic patient It is important to establish necessary working distances of the patient and this may require consultation between doctor, optician and patient Patient needs to be educated to understand that power determines working distance Vertex Distance Generally, vertex distance is only a consideration in high powers In contact lenses we consider vertex when the power is greater than 4.00 diopters In spectacles we usually consider vertex at 7.00 diopters 6

7 Vertex Distance If the refractionist is not indicating refractive vertex on the Rx. form for stronger powers, call or contact the doctor to be certain Evaluating is as simple as increasing and decreasing vertex of patient glasses Base Curves and Vision Base Curve The curve from which all other curves are determined Base Curve decisions should be made by the lens manufacturer or laboratory Base Curves and Vision Improper selection of base curves will lead to increased problems of optical aberrations The only time I consider going off the recommended base curve is if I need to modify magnification to provide binocular vision to a patient that would otherwise not have it Optical Aberrations in Lenses The creation of a blurred or distorted images due to the physical properties of a lens or lens material. These aberrations tend to create problems in high powered lenses Unequal Chromatic Aberration refraction of different wavelengths of light Abbe value determines the amount of chromatic aberration Chromatic Aberration Tends to be a problem in low Abbe value lenses that are often used in high powers 7

8 Generally found in high powered lenses Can be controlled with aspheric lens designs Distortion The effects of plus and minus lenses Distortion A visual image of the effects of distortion in plus and minus lenses Distortion Also called marginal Oblique Astigmatism astigmatism Light passing through the lens focuses away from the horizontal or vertical meridians Lens designers can usually control the problem Oblique Astigmatism The visual effects of oblique astigmatism An optical defect caused by peripheral rays focusing at different points along the optical axis Spherical Aberration 8

9 Spherical Aberration The image viewed through a lens with spherical aberration has a noticeable softness to it. A defect Coma in Aberration the imaging of objects off the optical axis in which there is a bright central area and a tail of lesser brightness A lens designed without correction for coma will cause the viewed images to have a comet-like extension. Coma Curvature of Field An image defect that causes offaxis image points to focus in different planes Can be minimized in lens design The center of the image is in focus, while the periphery is out of focus Curvature of Field Increased Problems magnification Associated or minification, With both from the patient s and viewers Strong Lenses perspective Increased weight Increased thickness (cosmetic appearance) Potential for problems with prism Potential for problems with vertex distance 9

10 Aniseikonia Unequal retinal image sizes for the two eyes Usually the result of unequal refractive errors May be resolved with iseikonic lenses Visual discomfort due to: Unequal retinal image sizes Unequal prism differences at near point Unequal focus Factors That Contribute to Magnification in Spectacle Lenses Power Thickness Radius of Curvature Generally Magnification an inconsequential side-effect of corrective lenses Problematic when the wearer undergoes changes in correction or when significantly different in each eye Plus lenses produce magnification Minus lenses produce Handling There is not much Magnification that you can do, because you can t change the power, which plays the largest role in magnification Using a Flatter Front Curve You can reduce magnification by flattening front curve, but this may cause other optical problems (use high index) You can also reduce magnification by reducing thickness (high index and aspherics) 10

11 Using a Flatter Front Curve While the selection of a flatter curve has cosmetic advantages, it may have serious optical disadvantages In anisometropia, compromises must be made We might choose to sacrifice usable lens area to equalize image magnification, and achieve binocularity Understanding Minimum Considering Minimum Blank Blank Size Size helps us to control lens thickness and weight MBS = ED + 2 (distance decentration) ED is the longest radius of a boxed lens shape of stress that may Stress in Lenses cause the patient to experience visual problems The first is stress created in the manufacturing process The second is created by poorly sizing lenses or The Stress in Lenses colmascope or polariscope are used to view stress in lenses Proper lens sizing and shaping are important to reduce stress For a plus lens, incorrect pantoscopic tilt Face Form, Wrap and Tilt will induce extra + sphere and + cylinder on the 180 axis. For a minus lens, incorrect pantoscopic tilt will induce extra - sphere and - cylinder on the 180 axis. To avoid, make sure that the MRP is 1 mm below the pupil center for every 2 degrees of pantoscopic tilt. (Do not use retroscopic tilt for an MRP that is above the pupil. Find another way to fix this problem.) For a plus lens, incorrect face form will Face induce Form, extra + sphere Wrap and + and cylinder Tilt on the 90 axis. For a minus lens, incorrect face form will induce extra - sphere and - cylinder on the 90 axis. To avoid, use some face form if the MRP is decentered in, and use no face form if there is no decentration. If there is a lot of decentration then there should be more face form. (Do not use negative face form if the MRP is decentered out.) 11

12 With frames that are designed Face to wrap Form, around Wrap the face, and Tilt compensation is indicated and often, that compensation is very difficult to verify Nonetheless, it is important to consider and the measurements that are utilized are most accurate if taken with the newer computerized measuring devices that are finding their way into the market Abbe Value and Chromatic Aberration Abbe Value (Nu Value) is a number assigned to each lens substrate material that denotes its relative dispersion The lower the Abbe value the greater the dispersion While this can be a problem for some patients, it is most likely to be a factor in higher powers, larger frames and in cases where the lenses have niot been centered both horizontally and vertically 1 st Time Multifocal The important elements of successfully fitting multifocals are: Pre-adjustment of frame Established fitting point bifocal, trifocal, progressive Careful explanation of expectations Demonstration of how the lens power(s) establishes working distance How to overcome a forty year habit Segment Placement in Multifocals Vertical Placement of Segment Bifocals Lower edge of limbus (6 o clock) Trifocals Lower edge of pupil in normally lit room Progressives Center Pupil Occupational Lenses These may differ from lens to lens, but typically are There Segment is no question Placement that the vertical in placement of the segment of any Multifocals multifocal is likely to be the most likely reason for a patient to have difficulty adjusting to multifocal wear The second most likely reason for nonadaptation is the improper horizontal placement of the segment Remember that the selection of the segment may also impact on the possible effects of vertical prism imbalance at the reading level Optical Center Placement There in are Single a number of Vision different circumstances that virtually necessitate the centering of a single vision lens vertically: High Powers High Index Aspheric/Atoric Anisometropia 12

13 Binocular Vision It is important to achieve or maintain binocular vision in all patients that are capable of achieving it. It is not disclosed on the Rx. that a patient is or isn t capable provide itofbinocularity Elements Necessary for Binocularity Image size needs to be close in each eye Image location must be similar on both retinas Check with doctor and do what is necessary to provide it Aniseikonia Aniseikonia is a difference in retinal image is controlled by: Magnification due to power (front curve) Effects of thickness Iseikonic Lenses Iseikonic lenses use changes in shape and thickness in an attempt to get the image size difference closer Online iseikonic lens calculator: ools/isizeseikonic.html 1 st Time Cylinder Power - Make sure that you r patient knows Astigmatism they have astigmatism and explain what it is Try to help them to understand the importance of the positioning of the powers Let them know that there may be a short period of adaptation needed When Prism is Prescribed Careful verification of the prism is essential. Remember the position of the Prism Reference Point must be established relative to the line of sight Doctor errors are possible here 13

14 Vertical Prism in Single With the larger Vision frames that are currently getting popular again, the vertical position of the eye relative to the frame geometric center is important to consider to avoid prism problems Vertical Prism Imbalance Take a Single vertical measurement Vision of the position of the pupil as you would with a progressive and position the OC or PRP about four mm. below that point to compensate for the pantoscopic tilt Vertical Prism This becomes even more of an issue if anisometropia exists As little as 1 diopter difference in the vertical meridian will potentially cause a loss of binocularity Anisometropia Significant difference in the refractive errors of each eye. Exists if refraction differs by 1.00 D or more. Will cause problems at near point. May cause problems in distance if not centered vertically ANTIMETROPIA: Other conditions: Difference in refractive errors resulting in two different image sizes. Prescription will always have opposite signs in each eye. ANISEIKONIA: Difference in retinal image sizes between two eyes. Induced by spectacles. Visual discomfort due to: Unequal retinal image sizes Unequal prism differences at near point Unequal focus 14

15 Anisometropia: Causes May be congenital May develop gradually in the natural course of the development of ametropia May appear suddenly following disease or surgery Symptoms Asthenopia- headaches, discomfort, burning, photophobia, pulling, or fatigue Inaccurate distance judgements Nausea or dizziness Intermittent double vision, relieved by closing one eye Complaints often express what patient feels rather than what they see Rx problems cover a broad range O.D O.S O.D x 180 O.S Horizontal Imbalance Problems Using the Rx O.D O.S Looking left will cause base out prism in OD O.D O.S O.D x 90 O.S x 180 Looking right will cause base in prism in OD SINGLE VISION DISPLACEMENT Correction for Horizontal Imbalance: Eye is capable of horizontal fusion of large amounts of prism. O.S. Nose O.D. Patient self corrects this problem by turning their head in direction of gaze 15

16 Vertically, Vertical anisometropia Problems causes vertical imbalance. Rx s with varying amount of power in the 90th meridian create opposing or unequal amounts of prism at the reading level. Average person tolerates vertical imbalance of up to 1.5 prism diopters. What is Vertical Imbalance? Simply vertical imbalance is a loss of visual clarity at the near point resulting from prism effect in the 90th meridian. Prism Theory Prism Displacement Rays of light traveling through a prism are displaced towards the base. Images viewed through a prism are displaced towards the apex 1 cm 1 M Image Displacement 1 cm 1 M Who is Not Bothered by Single Vertical vision wearers Imbalance may not be? bothered. They experience 0 prism through the optical center of their glasses, and adjust their head position. In the case of unequal Rx s but only good acuity in one eye. Patient is only getting acceptable acuity in one eye only. No imbalance induced. 16

17 Who is Bothered by Vertical Imbalance? First time multifocal wearers that have a decided difference in Rx s of each eye. Multifocal wearers with good acuity but whose Rx has changed sufficiently to induce 1.5 prism diopters of vertical imbalance or more. A person who recently had an intraocular implant due to cataract removal with resulting anisometropia. How can Vertical Prism Imbalance be Compare identified old Rx to new? Rx. Compare old lens style to new lens style. Determine power in the 90th meridian. Determine the reading depth or drop. Use Prentices Rule Base Directions - Plus Lens Base Direction - Minus Lens 17