Scleral lenses exhibit minimal tear exchange, especially compared to other contact lenses, such as soft and corneal rigid lenses.^1-3 Scleral lens complications can include post-lens fluid reservoir debris, midday fogging, and corneal hypoxic stress; all are exacerbated with extended lens wear.⁴ One approach to enhance tear exchange during scleral lens wear to reduce complications is to incorporate lens modifications such as fenestrations, notches, or channels.

A recent study aimed to quantify the result of modifying the landing zone on tear exchange during short-term scleral lens wear.⁵ Nine healthy adults who had normal corneas and a mean age (standard deviation) 34 (6) years wore scleral lenses with 3 distinct landing zone modifications in a randomized order. The modifications were toric landing zone (control condition), peripheral notches, or channels.

Lens parameters did not vary except for peripheral lens modifications. All lenses used a 150 µm toric landing zone to reduce rotation⁶ and account for potential differences in tear exchange related to landing-zone toricity.⁷

Participants were fitted with scleral lenses in hexafocon A material (Dk 100), with a back vertex power of −1.00 D, diameter of 16.5 mm, nominal center lens thickness of 300 µm, and back optic zone radius of 7.46 mm. The initial central fluid reservoir thickness ranged from 300 µm to 500 µm.

Noninvasive profilometry images were captured over a period of 100 minutes after the application of 10 µL of 2% sodium fluorescein. After 90 minutes of lens settling, sodium fluorescein was reapplied to assess tear exchange. Fluorescent intensity data located centrally and peripherally were obtained from the profilometry images and analyzed using customized MATLAB software.

The intensity of fluorescence varied significantly with time, lens design, and location on the cornea. Averaged across all time points, the peripheral channel lens design provided greater fluorescent intensity compared to the notched design and toric control lens, particularly in the corneal periphery. In contrast, the notch design displayed reduced fluorescent intensity, indicating a lower level of tear exchange compared to both the channel and toric lenses.

Following sodium fluorescein reapplication after 90 minutes of lens wear, the channel design showed a greater increase in fluorescence intensity at 10 minutes, compared to the toric and notch designs, averaged across central and peripheral locations. Tear ingress was consistently increased with the channel design, particularly in the periphery. The channel likely reduces contact between the landing zone and the underlying tissue to create a preferential flow pathway and possibly improve tear dynamics.⁵ These results provide quantitative support that channel modifications enhance short-term tear exchange and may guide future innovations in scleral lens customization.

References

1. Iqbal A, Fisher D, Alonso-Caneiro D, Collins MJ, Vincent SJ. Quantifying tear exchange during rigid contact lens wear using corneoscleral profilometry: A proof of concept study. Ophthalmic Physiol Opt. 2025;45(3):598-606. doi: 10.1111/opo.13450

2. Kok JH, Boets EP, van Best JA, Kijlstra A. Fluorophotometric assessment of tear turnover under rigid contact lenses. Cornea. 1992;11(6):515-517. doi: 10.1097/00003226-199211000-00005

3. Paugh JR, Chen E, Heinrich C, et al. Silicone hydrogel and rigid gas-permeable scleral lens tear exchange. Eye Contact Lens. 2018;44(2):97-101. doi: 10.1097/ICL.0000000000000400

4. Walker MK, Bergmanson JP, Miller WL, Marsack JD, Johnson LA. Complications and fitting challenges associated with scleral contact lenses: A review. Cont Lens Anterior Eye. 2016;39(2):88-96. doi: 10.1016/j.clae.2015.08.003

5. Iqbal A, Fisher D, Alonso-Caneiro D, Collins MJ, Vincent SJ. Peripheral scleral lens modifications and tear exchange. Cont Lens Anterior Eye. 2025 Apr;49(2):102617. doi: 10.1016/j.clae.2026.102617

6. Alexander J, Belaineh Aweke Y, Bhebhe Z, et al. The effect of landing zone toricity on scleral lens fitting characteristics and optics. Ophthalmic Physiol Opt. 2024;44(5):867-875. doi: 10.1111/opo.13324

7. Iqbal A, Fisher D, Alonso-Caneiro D, Collins MJ, Vincent SJ. Scleral lens landing zone toricity and tear exchange. Cont Lens Anterior Eye. 2026;49(1):102571. doi: 10.1016/j.clae.2025.102571 

Melissa Barnett, OD, FAAO, FSLS, practices at Baker Optometry. She also is an International Coaching Federation (ICF) associate certified coach. She has received remuneration from ABB, AbbVie, Alcon, Azura, Bausch + Lomb, BCLA, Bruder, Cloudbreak Pharma, Dompé, Epion, OCuSOFT, ScienceBased Health, STAPLE Program, Tarsus, and Théa Pharma.

 This content was supported by Contamac.