Fitting SpecialEyes Multifocal Toric Contact Lenses- Custom Multifocal Optics Prove Successful
The final post in this series highlights a case in which a practitioner called SpecialEyes to design custom multifocal toric contact lenses for a 48-year-old female. The patient complained of decreased near visual acuity with her current soft contact lenses (brand and type unknown). She had previously worn RGP lenses but wanted to remain in a soft contact lens.
OD: -6.50 -1.75 x090 20/20
OS: -6.00 -2.00 x110 20/20
Add: +1.75 OU 20/20
The patient’s pupil-size measurements were not available during the initial lens design, so the custom multifocal toric contact lenses were created with a standard 2.0mm near-center zone and 4.0mm peripheral zone.
Contact Lens Trial #1:
SpecialEyes 54 Multifocal Toric Contact Lenses:
OD: 7.8 Base Curve/14.4 Diameter -6.00 -1.50 x090 +1.75 add
OS: 7.9 Base Curve/14.7 Diameter -5.50 -1.75 x110 +1.75 add
Multifocal Optics: 2.0mm near-center zone/4.0mm peripheral zone
Initial Dispense: The lenses were centered, demonstrated good movement, and showed stable rotation aligned at 180 OD and rotated 5 degrees right OS.
Near OU: J1
The lenses were dispensed to the patient so she could try them in her “real-world” environment.
Follow-Up Visit – Chief Complaint: Upon returning to the practice after wearing the initial lens trial, the patient complained of poor vision in low light and the need to wear reading glasses both for computer work and near work. Despite the acuity concerns, the patient reported she was very satisfied with the comfort of the lenses.
Decreased Visual Acuity at Follow-Up Visit:
Near OU: J4
Action: Redesign the multifocal optics based on a pupil measurement of 5.0mm in regular room illumination. The near-center zone went from 2.0mm to 2.5mm and the peripheral zone went from 4.0mm to 5.0mm.
The simulated images below provide a visual representation of the potential performance of both lens designs based on a 5.0mm pupil in regular room illumination and a 6.0mm dilated pupil measurement in a lower-light setting.
Interpretation: Simulations #1 and #2 above represent the first set of trial lenses. The simulated images show that near and intermediate vision is degraded with this multifocal design, especially in Simulation #2, which illustrates vision in a low-light setting (dilated pupil of 6.0mm). The patient’s visual acuities at the follow-up visit were 20/30 at distance and J4 at near, with complaints of poor vision in low-light settings and difficulty with computer and near work.
Reminder of Action Taken: The multifocal optics were redesigned based on a pupil measurement of 5.0mm in regular room illumination. The near-center zone went from 2.0mm to 2.5mm and the peripheral zone went from 4.0mm to 5.0mm. Simulations #3 and #4 below provide a visual representation of the redesigned lens with optimized multifocal optics.
Interpretation: Review the images in Simulations #3 and #4 above and compare them to the previous images in Simulations #1 and #2. Redesigning the multifocal optics to accommodate the larger pupil improved near and intermediate vision significantly both in regular room illumination and in a lower-light setting, as demonstrated by the simulated images. The improvement illustrated in Simulations #3 and #4 corresponded directly to the patient’s improved visual acuities with the second set of trial multifocal toric contact lenses, which were designed using the Multifocal Simulator. Distance visual acuity improved from 20/30 to 20/20- and near visual acuity from J4 to J1 at the final follow-up visit.
Final Outcome: Redistributing the 54 Multifocal optics according to the patient’s pupil size and chief concerns proved successful. This indicates that pupil size and the manner in which the multifocal optics are distributed have a significant impact on multifocal toric contact lenses. By increasing both the near-center and peripheral zones in the second set of lenses, the revised multifocal design improved the patient’s distance and near vision as well as her vision in low-light settings. It’s worth noting that no other contact lens parameters were altered apart from the zone sizes to result in this success. This case may help explain why some multifocal toric contact lenses are unsuccessful despite attempts at over-refracting.
If you would like more information on fitting custom soft multifocal toric contact lenses provided by SpecialEyes, don't hesitate to call our consultation team. We also encourage watching the Multifocal Simulator Demo Videos and requesting a ruler to assist in accurate pupil size measurement. Stay tuned for more posts to come!
The SpecialEyes Consultation Team