Fitting Tip Archive
12/28/09 – Intelliwave: It is always beneficial to note any previous patient order history of soft lens base curve, diameter and powers when designing Art Optical’s Intelliwave soft lenses. Knowing what has worked for the patient in the past can aide in narrowing down the custom fitting parameters on the initial order.
12/21/09 – Renovation Multifocal: It is very beneficial, when choosing Renovation for your patients, to consider any current or previous GP single vision lens parameters. In many cases you can use that information for the Renovation order if the single vision fit is working well. We also recommend that you note the patient’s approximate pupil diameter in normal illumination to assist with any changes required in the size of the distance/intermediate zone if the standard zone diameter is creating any difficulties.
12/14/09 – Bi expert: For the Biexpert segmented design, it is important to measure the distance from the patient’s lower lid to lower pupil margin to assist in determining the segment height needed.
12/7/09 – Against-the-rule Astigmatism: For patients with high amounts of against the rule refractive cylinder we recommend ordering a spherical lens first and then performing a sphere/cylinder/axis over refraction to determine the exact power needed for a front toric.
11/30/09 – Post Corneal Transplant Fitting: Art Optical consultation will always begin with a Boston Envision lens design for post corneal transplant patients. The Boston Envision design has shown excellent success for these patients and has worked better than any other design option we have tried.
11/23/09 – Reverse Geometry Fitting: Did you know that the control of the optical zone diameter on a reverse geometry GP lens design is completely opposite of a conventional spherical lens? A smaller optical zone diameter on a post LASIK/RK patient will generate a steeper fit relationship and a larger optical zone diameter will produce a flatter fit relationship. This is due to the altered central corneal curvature being flatter than the untreated cornea. A normal treatment zone for LASIK is 6.0 mm, if the optical zone diameter is less than 6.0 mm the reverse curve will start inside the treatment area and result in a steep fit pattern. When the optical zone diameter is excessively larger than the treatment area the lens fit will have a flatter affect. Art Optical recommends an optical zone diameter of 7.0 mm for most reverse geometry lens designs.
11/16/09 – Plasma Treatment: When GP lenses are plasma treated they arrive in a soaking solution but are not sterile. They should be cleaned with a non-abrasive cleaner and then placed in a soaking solution for at least 4 hours before dispensing to the patient.
11/9/09 – GP Lens Care: We recommend that new GP lenses be soaked in conditioning solution for a minimum of 4 hours before they are verified in the office. This allows the lens to hydrate completely and will prevent oils and debris from attaching to the surface during the verification process. Handling a new GP lens before it is fully hydrated can actually cause surface wetting issues.
11/2/09 – SoClear: Bubbles are often present in this design so it is important to evaluate the size, shape and appearance of the bubbles to determine if the fit is acceptable. Images of Fluorescein patterns are available to view on our website to further aid in determination of fit being too flat or too steep.
10/26/09 – Adjusting Lens Power: When an over refraction in the phoropter is greater than +/-4.00, be sure to vertex it before adding it to the current contact lens power.
10/19/09 – Renovation multifocal: Pupil size can come into play when using the Renovation design. At initial evaluation, measure the pupil in normal room lighting. If it is under a 4.0, we would recommend starting with a 3.5 mm distance zone to help the patient achieve quicker access to the add power.
10/12/09 – Surface wetting tip: To achieve the best surface wetting characteristics for your patients, advise them to clean their lenses in the evening and allow them to soak in a conditioning solution overnight.
10/5/09 – Renovation multifocal: At initial dispensing of the Renovation design, if the patient has good comfort and distance acuity but does not obtain good near vision, send them home with the lenses. As with any aspheric/progressive multifocal design, patients may need to learn how to find and utilize near power.
9/28/09 – Intelliwave: Parameter changes should not be made based on evaluation at initial dispense. It is advisable to not change the power until the first follow-up visit. If acuity is reasonable, send the patient home with the lenses so they can achieve some wearing time prior to making any changes to the fit or the power.
9/21/09 – SoClear: Make sure the patient uses a few drops of a wetting solution on the eye before attempting removal. While most patients can remove the SoClear lens using conventional removal techniques, some patients may need to use a rigid lens suction cup to assist removal. When using a suction cup, place it on the periphery of the contact lens. This will help break suction between the lens and the cornea and make the lens easier to remove.
9/14/09 – Renovation multifocal: Because Renovation has a spherical base curve, it is ideal for converting current single vision lens wearers to a presbyopic design. You can often use the same single vision lens parameters and just incorporate the add power on the front surface to achieve an excellent multifocal affect.
9/7/09 – Keratoconic fitting: When assessing a keratoconic fit using our AKS modality, we generally recommend the 3 point touch philosophy which shows slight central touch (1 to 2mm), a mild mid-peripheral touch that has less than 360 degrees of bearing, and minimal edge clearance in the periphery. Remember that if corneal topography is not available, Art Optical has loaner fitting sets ready to aid you in the fitting process. Contact our consultation department to determine which set will work the best for your patients.
8/31/09 – Mid peripheral bearing: Always look for an aligned and even pattern in the center, mid-periphery and periphery of a GP lens fit. If a fluorescein pattern shows mid-peripheral bearing that is 360 degrees in nature, this indicates that the optical zone diameter is too large for the base curve that is being used. Adjust for this by reducing the optic zone diameter by .30 mm and flatten the base curve by .25 Diopters. This will bring the fit into better alignment with the corneal curvature.
8/24/09 – Over refraction changes: Remember that a change in lens power due to an over refraction does not generally require a change in base curve or the general fit of the lens. This is true with both single vision and multifocal GP lens designs.
8/17/09 – Dry eye option: The use of overnight Orthokeratology can aid low to moderate myopic patients who want to wear contact lenses but have dry eye issues that prevent them from achieving an all day wearing schedule. Having the lenses worn overnight and removed in the morning can provide freedom from spectacles while eliminating the wetting issues associated with daytime contact lens wear.
8/10/09 – Lens cleaning: When there is a wettability or deposit issue on one lens only, particularly OD lenses, this may not always be due to a material or fit issue. Make sure to review the possibility of surface contaminants causing the problem. Patients tend to clean and handle OD lenses first and any residual soaps or lotions that may be on a patients hand tend to primarily affect the lens that they handle first. There are a number of hand soaps available for contact lens users. Make sure that the soaps used to wash hands prior to the handling of a contact lens do not have Aloe or Lanolin.
8/3/09 – Multifocal GP translation: When assessing the translation of multifocal GP lens, look for upward lens movement on the downward gaze. If the overall fit looks good but the lens drops below the lower lid when gazing down, alter the fit by going larger on the diameter and slightly steeper on the base curve fit. When in doubt, contact our consultation department for further assistance.
7/27/09 – Refitting Tip: Before refitting a walk-in patient who exhibits corneal molding or irregular mires from previous rigid lens wear, consider having the patient go without their lenses for 3 to 7 days to allow the corneas to stabilize.
7/20/09 – Multifocal contact lenses: Use loose lenses for over refracting multifocal contact lenses. Always start with +0.25 OU and work up from there. If you start with +1.00 the patient will accept this through the distance power and you will not know how much they truly need to adequately correct their near vision.
7/13/09 – Intelliwave multifocal: Some moderate to high with-the-rule astigmatic presbyopic patients just can not adapt to GP lenses. This would be a good opportunity to try the Intelliwave toric multifocal option. It has the same guaranteed fit as our GP multifocal designs and has been achieving very good success for many patients. This would also be the first lens of choice for the against-the-rule presbyopic astigmat.
7/6/09 – Renovation E and MagniClearplus: We have consulted on many patients who were wearing MagniClear Plus in a low minus or plus distance power and now require higher add powers. The higher add power generates a dramatic increase in center thickness and could cause the lenses to position low because of the increased mass. This is a good opportunity to switch to Renovation E. Renovation E will substantially reduce the center thickness compared to MagniClear Plus and provide much better lens centration.
6/29/09 – Base curve adjustment: If an initial set of GP lenses happens to have base curve differences of .50 to 1.00 D and the fit of one eye appears to be too flat or steep, this is a good opportunity to use the lens from the other eye as a trial. You may find that the other lens works well or that you still need to change the fit more or less than what you initially thought. You can use this information to narrow down what needs to be done for a final lens change.
6/22/09 – Exploring all options: Our Consultation staff spoke with a practitioner who noted that one of his elderly patients stated they had a lazy (amblyopic) eye and was never able to see clearly through it. Upon testing the vision, the unaided acuity was 20/400. The practitioner was surprised to find that refraction corrected the acuity down to 20/30 and a toric GP lens was a perfect option! The patient noted that previous practitioners’ had not attempted to correct the vision in that eye for many years and had just written it off as unusable. This patient now has binocular vision and is forever grateful to the practitioner for attempting to correct what was once thought to be uncorrectable.
6/15/09 – Renovation and Renovation E: Renovation and Renovation E are some of the thinnest multifocal designs available anywhere. This aids in comfort and centration but could cause unwanted lens flexure on corneas with higher amounts of with-the-rule corneal cylinder. If lens flexure occurs we recommend increasing the center thickness .03 to .04 mm to eliminate it.
6/8/09 – Renovation and Renovation E lens position: These designs should position centrally, or even slightly high, at straight ahead gaze. When instructing the patient on how to obtain near vision, have them keep their head straight and shift their gaze down to read. Ask them to move the reading material up or down to get the best reading image. Once they have found the most affective near area, they should have no problems adjusting to their best reading position.
6/1/29 – Defecting lens flexure: Are you suspecting lens flexure due to reduced or fluctuating acuity caused by residual cylinder that should typically be masked by a GP lens? This can be confirmed by retaking K-readings while the patient is wearing the lens. You will get a spherical K over the lens if no flexure is present. If there is lens flexure you will get a K reading that shows toricity. If this is the case, then adjust the fit by using a flatter base curve and/or an increased center thickness of .03 to .04 mm.
5/25/09 – Thinsite and Thinsite 2: Thinsite, and now also, Thinsite 2 are good options for myopes who are experiencing 3 and 9 staining with a standard single vision GP lens. The edge thickness is dramatically reduced allowing better tear spread to the peripheral cornea. Thinsite is also an excellent option for first time GP lens wearers and patients converting from soft to GP lenses. Consider Thinsite for your hyperopic patients as well. It will not position low in moderate to high plus powers, in fact, we have found that long term GP wearing hyperopes and aphakes often do not appreciate the reduced thickness and better positioning of Thinsite since they have fully adapted to a thicker and heavier lens that sits low.
5/18/09 – Renovation Multifocal: Are your patients’ Renovation lenses positioning too high? If the fit looks good but the lens rides high, we suggest using a large diameter and/or increasing the center thickness to assist the lens in centering better. Not all high riding multifocal fits are a problem. You only need to consider lowering the position if the distance or near vision is compromised or if the high position is causing spectacle blur upon lens removal. If the lens positions above the superior limbus, the fit should be adjusted.
5/11/09 – Converting PMMA lens wearers to GP’s: It is rare to have a patient who is wearing PMMA lenses but they still do exist and should be refit in a GP material whenever possible. Trying to refit the patient using Keratometer readings and spectacle prescription using a high DK GP material could lead to a bumpy transition period. We recommend staying very close to the same specifications the patient was wearing in PMMA and to use a mid-range DK GP material (26 to 32 DK). This will allow the cornea to receive increased oxygen at a controlled rate and prevent wild amounts of rebound. You can consider moving to a higher DK material after the patient has successfully transitioned from PMMA to a mid-DK GP material.
5/4/09 – Fluorescein evaluation of high minus GP lenses: When evaluating the fluorescein pattern on high minus lenses in a material with a UV blocker, it can sometimes appear like there is mid peripheral bearing and that the fit is too steep. This can be caused by the increased peripheral thickness generated by the minus power. The blue cobalt filter will not provide full penetration through increased thickness of a UV blocking material. It is advised to use a #12 Yellow Wratten filter along with the cobalt filter to avoid these false images. The yellow filter will not be affected by UV blocking materials.
4/27/09 – Reviewing corneal topography: Analyze the image results to make sure they were captured properly. The topographical images should make sense based on patient history of a normal cornea, post surgical, cone, etc… If both eyes are similar in refraction and manual keratometry, the topographies should also be similar. If the patient is not focused correctly or there is a lack of tear film at the time the image is captured, the topography can show unusual results that are typically easy to catch.
4/20/09 – Accessing the GP lens fit: There are typically three factors to consider when determining changes to the fit of a GP lens. 1. Where is the lens positioned (centered, low, high, temp, nasal)? 2. What is the appearance of fluorescein pattern (edge lift, mid peripheral bearing, bubbles, etc)? 3. How is the movement on the blink (minimal/none, slow, fast, erratic/jumpy)? Consider them all prior to making any changes in the fit relationship.
4/13/09 – SoClear corneal/scleral trial lens evaluation: We recommend using sterile saline and not conditioning solution for trial lens insertion to evaluate the lens fit. The use of a conditioning solution may cause the fit to appear flatter than it actually is due to the viscosity of the conditioning solution.
4/6/09 – Irregular Corneas: Contact lens fitting on irregular corneas can be challenging. It is recommended to start with either a fitting set or design the lens based on corneal topography. Art Optical has loaner sets on hand to cover a wide range of conditions. Our fitting consultants are also readily available to assist with lens designs from topography.
3/30/09 – Understanding GP material: High Dk Gas Permeable materials provide the greatest advantage for long term corneal health; however, there can be a trade-off with wettability for patients with compromised tear volume or chemistry. When wetting is an issue with a high Dk material, consider plasma treatment to resolve this before prescribing a more moderate Dk material.
3/23/09 – When Faced with 3 or more Diopters of Cylinder: Consider back or bi-toric lenses when there is 3.00 diopters or greater of with-the-rule corneal cylinder. When there is 3 diopters or greater of against-the-rule corneal cylinder, it is recommended to have corneal topography done to rule out PMD (Pellucid Marginal Degeneration).
3/16/09 – Contact Lens Tip: When considering contact lenses for a patient and the spectacle refraction and keratometer measurements are substantially different for each eye, this could indicate a problem. Review the patients previous history to compare current to past findings. If the patient is new to your practice, request the past history from their previous practitioner including any contact lens parameters that may have been prescribed.
3/9/09 – Sending Topographies: Art Optical’s fitting consultants can provide increased customized fitting assistance when topography is available for review. The evaluation process is most accurate when the map is set in a normalized scale. The normalized scale shows the range of curvature from the flattest to steepest point for each individual cornea.
3/2/09 – Lens Care Tip: To aid in lens cleanliness, instruct patients to digitally clean their lenses after removal at day’s end prior to leaving the lenses soaking in solution overnight. Lens deposits will be easier to remove when the lenses are at body temperature and will ensure lipids and other forms of debris do not have a chance to solidify at cooler temperatures. Reinforcing the advantages of freshly cleaned lenses, added to fresh solution (not topped-off) in a clean case, will create the optimum overnight cleaning and conditioning environment for lenses. The morning routine should include another digital clean and rinse, followed by a daily rinse of the lens case using a conditioning solution.
2/23/09 – Diameter Selection: We often base diameter selection on the keratometer readings. The general rule is the flatter the cornea, the larger the lens and vice versa.
2/16/09 – Multifocal Add Selection: When determining the add power for most GP multifocals, we have found that it is best to start about .50D more than the patient refracts. However, with our Intelliwave multifocal lenses, which are a center-near design, it is best to start right at the patients refractive add.
2/9/09 – Fitting an Intelliwave lens: Parameter changes should not be made based on evaluation at initial dispense, but rather at the follow-up visit (1wk). If acuity is reasonable, send patient home with the lenses so they can get in some wear time as fit/acuity can change as lenses settle.
2/2/09 – Fitting a Renovation or Magniclear Plus lens: If a patient complains these lenses are difficult to remove and the fit looks appropriate (good fluorescein pattern, good centration, and movement), minimal changes should be made. This can be done by flattening the base curve by only 0.25D and increasing the edge lift from the standard .11 to .14. This will allow for easier removal without losing the fit.