One of the many indications for scleral lenses is to rehabilitate the surface of the eye in ocular surface disease (OSD) which is a highly prevalent and chronic condition with a multitude of ocular and systemic causative factors. The beauty of scleral lenses is the post-lens fluid reservoir that provides continuous lubrication of the cornea and conjunctival tissue.
A recent study evaluated the anterior scleral lens surface and ocular surface wettability before and after one month of scleral lens wear in patients with keratoconus.1 Previous studies have demonstrated that soft and rigid contact lens wear adversely affect the Tear Film Surface Quality (TFSQ) using videokeratoscopy.2-4
A total of 49 patients with keratoconus (age 36.26 ± 9.03 years) were included and separated into two groups: patients with intrastromal corneal ring (KCICRS group) and patients without ICRS (KC group).
Testing was performed at two different visits. The first visit was prior to lens wear (baseline) and the next visit was 10 minutes after lens removal (one-month visit). Schirmer I, Ocular Surface Disease Index (OSDI questionnaire), tear break-up time (TBUT), corneal staining and TFSQ were evaluated at both visits. TFSQ was measured by a corneal topographer (E300; Medmont, Melbourne, Australia) by high-videokeratoscopy system. This topographer is based off a Placido disk technique that is reflected from the surface of the tear film on the ocular surface or anterior surface of a contact lens. Additionally, the Visual Analog Scale (VAS questionnaire) was completed immediately after scleral lens insertion and just prior to scleral lens removal.
This study determined that anterior corneal surface TFSQ values increased in all groups after scleral lens wear (p < 0.05). No statistical differences were found at the moment of lens insertion or after 8 hours of lens wear (p > 0.05). There were not any changes in tear volume for all patients in general and in the KC and KCICRS groups (p > 0.05). A statistically significant decrease of TBUT (p < 0.05) was found in all groups. Additionally, OSDI, corneal staining and VAS improved after scleral lens wear from baseline in all groups and in both KC and KCICRS groups (p < 0.05).
There were no statistical differences in the TFSQ of the anterior contact lens surface between baseline (before lens fitting) and after one-month of scleral lens wear in this study, indicating no contact lens wettability changes. No difference in wettability changes may be considered a positive attribute of scleral lenses. Prior studies with both rigid and soft contact lenses showed that both adversely affect the TFSQ in both natural and suppressed blinking conditions. In these studies, there were not any significant differences between the lens types and materials.4
The authors suggest that long-term studies are needed to evaluate if the contact lens material loses its wettability due to deposits. A similar long-term study with a large sample size in different disease populations including a severe dry eye population would be valuable.
Serramito M, Privado-Aroco A, Batres L, et al. Corneal surface wettability and tear film stability before and after scleral lens wear. Cont Lens Anterior Eye. 2019 Apr 6. pii: S1367-0484(18)31023-3. doi: 10.1016/j.clae.2019.04.001. [Epub ahead of print]
D. Alonso-Caneiro, D.R. Iskander, M.J. Collins, Tear film surface quality with soft contact lenses using dynamic-area high-speed videokeratoscopy, Eye Contact Lens.
D.H. Szczesna-Iskander, D.R. Iskander, S.A. Read, D. Alonso-Caneiro, Noninvasive in vivo assessment of soft contact lens type on tear film surface quality, Invest Ophthalmol Vis Sci 53 (1) (2012) 525–531.
G. Tyagi, D. Alonso-Caneiro, M. Collins, S. Read, Tear film surface quality with rigid and soft contact lenses, Eye Contact Lens 38 (3) (2012) 171–178.
Dr. Barnett is a principal optometrist at the University of California Davis Eye Center in Sacramento, specializing in anterior segment disease and specialty contact lenses. She is the past president of the Scleral Lens Education Society. She is an advisor to and/or has received honoraria or travel expenses from AccuLens, Alcon, Alden Optical, Allergan, Bausch + Lomb, Bruder, Contamac, CooperVision, EveryDay Contacts, Johnson & Johnson Vision, Ocusoft, Paragon Bioteck, RaayonNova, ScienceBased Health, Shire, SynergEyes, and Visioneering Technologies.