How to choose the appropriate contact lens design from SpecialEyes
For patients with presbyopia and astigmatism, SpecialEyes offers two design choices- a custom aspheric multifocal and a custom annular bifocal contact lens. Both the SpecialEyes 54 Multifocal toric and the SpecialEyes 54 Bifocal toric contact lenses are fully customizable and can be manufactured in the same wide range of powers and parameters. So, how does one choose which custom soft contact lens design will be most successful for their patients with presbyopia and astigmatism? Today’s case study will give you insight on how the consultants at SpecialEyes make this distinction.
An astigmatic presbyope presented with a strong desire to wear soft multifocal toric or bifocal toric contact lenses. The practitioner used the online SpecialEyes Arc-Length Calculator to design a set of trial contact lenses. Just as he was about to email the order into SpecialEyes, he realized he was unsure which design should be chosen. He decided to call in the order to the SpecialEyes Team and find out their recommendations.
Upon speaking with a SpecialEyes Team Member, the practitioner was asked if the patient had ever tried any multifocal contact lens designs on the market. The practitioner communicated that the patient has tried various aspheric multifocal designs with little to no success. In the previous lens designs, the patient was not able to achieve the very crisp, clear vision at distance and near that is needed for his daily routine. The practitioner also mentioned that the patient did not adapt well to monovision, signifying that an enhanced monovision approach to fitting this astigmatic presbyope is not ideal.
We at SpecialEyes often describe this type of patient as hyper-critical. Hyper-critical presbyopes demand sharp visual acuity at distance and near and tend to be sensitive to any fluctuation in vision. The custom aspheric 54 Multifocal is often the go to option for most patients with presbyopia and astigmatism. Based on our experience however, hyper-critical, discerning eyes are more successful in our 2-zone custom annular-concentric 54 Bifocal contact lens design. We believe hyper-critical patients appreciate the distinct distance and near zone within the 54 Bifocal design, while the asphericity within 54 Multifocal’s intermediate zone contributes to their chief complaint of poor quality of vision.
Based on the patient’s previous lens wear history and visual expectations, the following trial contact lenses were ordered:
SpecialEyes 54 Bifocal Toric Contact Lenses:
OD: 8.6 Base Curve/14.5 Diameter -.75 -.75 x100 +1.25 add
2.20 Near Center Zone Diameter (based on 4.5mm pupil in ambient room)
OS: 8.6 Base Curve/14.5 Diameter -.50 -.75 x090 +1.25 add
2.40 Near Center Zone Diameter (based on 4.0mm pupil in ambient room lighting)
Trial #1 Results:
After inserting the bifocal toric contact lenses and allowing time to settle, a slit lamp exam revealed good fit with appropriate coverage, centration and movement on blink. Subjectively, the patient complained of poor near vision and slightly decreased distance vision. The patient also mentioned the lenses seemed thin and reported issues with handling. The initial trial bifocal toric contact lenses yielded the following visual acuity and exam results:
OD: 20/30(-) at Distance, J7 at Near
+.50 over refraction at distance
Stable 10 degree nasal or counter-clockwise rotation
OS: 20/25 at Distance, J7 at Near
+.25 over refraction at distance
Upon speaking with a consultant at SpecialEyes, a new set of trials were ordered based on the over refraction results and lens rotation. The SpecialEyes consultant also recommended increasing the near center zone diameter by .2mm to improve near vision and increasing the center thickness in both lenses.
As we hoped, the second pair of trial bifocal toric contact lenses was successful. After wearing the new trial lenses for a month with satisfaction, a supply was finalized as follows:
OD: 8.6 Base Curve/14.5 Diameter -.25 -.75 x090
+1.25 add 2.40 Near Center Zone Diameter
OS: 8.6 Base Curve/14.5 Diameter -.25 -.75 x090
+1.25 add, 2.60 Near Center Zone Diameter
Here are the clues that SpecialEyes used in deciding which contact lens design and type:
- Patient was unsuccessful in various brands of aspheric multifocal contact lenses on the market
- The patient’s daily routine presents a need for very crisp, clear vision at distance and near
- While visual acuity via Snellen chart was acceptable with aspheric multifocal contact lenses, the patient complained of poor quality of vision
- Did not adapt well to monovision
In conclusion, choosing which contact lens design will be best for your astigmatic presbyope is not as challenging as it may seem. Different lens designs will be successful for different patients. The key is fully evaluating the patient’s history and setting up realistic expectations. When in doubt, share the full story with your contact lens lab’s consultation team and try their recommendations.