GP lens eye Rounds

PRESBYOPIA: Scleral Multifocal Case

Emily Gottschalk OD, FAAO

Background: Optics in scleral GP lenses assume that the geometric center aligns with the patient’s visual axis. Scleral lenses commonly decenter inferior and temporal due to scleral elevation asymmetry, gravity, and eyelid forces.¹ Lens decentration and angle kappa can affect visual performance with multifocal scleral lenses that have smaller optic zones for center-near designs compared to single vision scleral lenses.² Simultaneous design of multifocal scleral lenses introduce spherical aberrations affecting quality of vision.³ Misalignment of spherical aberration can induce higher order aberrations like coma.³ Optics in scleral lenses can be decentered to align with the patient’s visual axis to promote optical alignment to improve visual acuity and reduce higher order aberrations. Scleral lenses can provide relief from dry eye symptoms4, prevalent in the presbyopic population.⁵ This case demonstrates the improvement in visual acuity and subjective visual quality of decentering multifocal optics in scleral lenses.

History

• HPI: 64 y/o WF with a history of mixed mechanism dry eye and ocular allergies
• CC: dry eye leading to discontinuation of soft multifocal contact lens wear
• Modifying factors: (+) Pataday

Examination

• Refraction/VAs:

OD +1.75 -0.50 x 012, 20/15-
OS +2.00 -0.75 x 178, 20/15-
+2.50D ADD

• Pupils:

OD 3.5mm bright; 4.5mm dim
OS 3.5mm bright; 4.5mm dim

• Slit lamp examination OU:

Decision-Making Process

A multifocal scleral lens fit was initiated to meet the patient’s goal of spectacle-free correction. Multifocal scleral lenses with front surface, center-near simultaneous vision were initially ordered. Hydra-PEG was included to increase lens wettability and minimize discomfort due to dry eye.

Fitting and Evaluation

The following design was fit OU and the visual results shown in Table 1.

Figure 1. Topography over contact lens showing inferior temporal decentration of center-near optics from visual axis.

Excessive inferior temporal decentration of the optics was found on topography over the contact lenses (Figure 1). The lens diameter was decreased to improve overall lens centration and the center-near optics were decentered superior-nasal the standard amount (Figure 2) with the goal of improving the patient’s subjective quality of near vision. (Table 2)

Figure 2: Topography over the contact lens showing slight superior temporal decentration of center-near optics from the visual axis. To further align the optics with the visual axis the center of the near optics can be measured and decentered along the appropriate axis.

Follow-Up Visit. The patient’s near complaint of ghosting was resolved with centration of the center-near optics within the pupil. The over-refraction was incorporated into the final lens order. The patient was happy with both distance and near vision and described excellent visual clarity at near with resolution of ghosting. Following centration of the center-near optics, the distance visual acuity (VA) decreased from 20/20 OD/OS to 20/25 OD/OS. Options to consider to improve distance VA include decreasing the center-near zone and decreasing the add power for both eyes or the dominant eye only.

Clinical Pearls

• • Decentered optics in multifocal scleral lenses have the potential to:
    • • Increase success of multifocal fits
      • Improve visual quality for presbyopes
      • Alleviate dry eye symptoms experienced at high rates in the presbyopic population
  • Fitting process for multifocal scleral lenses:

1. 1. 1. Finalize single vision scleral lens fit with emphasis on lens centration.
      2. Incorporate multifocal optics with standard decentration for the specific lens design (consult with laboratory)
      3. Ensure lens centration is optimized and then decenter optics according to topography

• • Rules of thumb:
    • • For excessive optical decentration on topography or lens decentration on examination, decrease lens diameter
      • For moderate optical decentration further adjust multifocal optics by measuring via topograph

Sources

1. 1. Ritzmann M, Caroline PJ, Börret R, Korszen E. An analysis of anterior scleral shape and its role in the design and fitting of scleral contact lenses. Contact Lens and Anterior Eye 2018;41(2):205–213.
   2. Vincent SJ, Alonso-Caneiro D, Collins MJ. The temporal dynamics of miniscleral contact lenses: Central corneal clearance and centration. Contact Lens and Anterior Eye 2018;41(2):162-168.
   3. Rae S, Conway R, Massey J, Jaworski A, Lanier K. Induced aberrations and visual performance in multifocal contact lenses. Contact Lens and Anterior Eye 2018;41:S23.
   4. Alipour F, Kheirkhah A, Behrouz MJ. Use of mini scleral contact lenses in moderate to severe dry eye. Contact Lens and Anterior Eye 2012;35(6):272-276.
   5. McCarty CA, Bansal AK, Livingston PM, Stanislavsky YL, Taylor HR. The epidemiology of dry eye in Melbourne, Australia. Ophthalmology 1998;105(6):1114-1119.