TITLE:
Evaluation of a Modified Scleral Contact Lens as a Riboflavin Delivery Device for Corneal Collagen Crosslinking
AUTHORS:
Ricardo Torres Soares, Neil F. Novo, Willy Marcus França
KEYWORDS:
Keratoconus, Riboflavin, UVA, Rigid Contact Lens, Cross-Linking
JOURNAL NAME:
Open Journal of Ophthalmology,
Vol.7 No.4,
October
31,
2017
ABSTRACT:
Introduction: Keratoconus is a complex corneal disease that reduces visual
acuity by progressively modifying the corneal shape and thickness, usually
producing myopia and irregular astigmatism. Corneal collagen crosslinking
with riboflavin + ultraviolet-A radiation (CXL) has become a widely accepted
treatment for progressive keratoconus. During CXL, riboflavin administration
is performed by repeated manual instillation of solution drops on the cornea
for 30 minutes, a procedure that is often uncomfortable for many patients and
that consumes surgical facilities and staff resources. In this study, especially
modified scleral contact lenses (MSCL) were employed for delivering riboflavin
to the cornea during CXL. Objective: The study aimed at evaluating the
safety and efficacy of MSCL as a drug delivery system, verifying if anterior
chamber flare confirms riboflavin penetration and describes the impact on
patient comfort and optimization of surgical staff and facility resources. Material
and Method: This study included 8 eyes of 6 patients aged 16 - 25 years
old with history of progressive keratoconus. After mechanical removal of
corneal epithelium, the concave surface of the modified scleral contact lens
was filled with riboflavin solution and the lens was placed on the patient’s eye
during 30 minutes. The lens design allows the formation of a riboflavin layer
between the lens and the exposed corneal stroma to facilitate riboflavin penetration.
Patients with lens were allowed to stand up and wait for the second
UVA phase outside the surgical room. Riboflavin diffusion was confirmed by
biomicroscopic examination of the corneal stroma and anterior chamber with
the lens in place. Patients returned and the lens was removed before UV-A irradiation
at 3 mW/cm2 for 30 minutes. Statistical analysis was performed by
comparing the following parameters of each patient pre- and post-CXL:
Spherical equivalent (Sph.Eq.), Mean simulated keratometry (SimK-m) and corrected distance visual acuity (CDVA) using the Wilcoxon method for
non-parametric data (p Results: The MSCL allowed patients to be
transferred from the surgical room to wait for corneal impregnation with riboflavin.
The MSCL was effective in delivering riboflavin to the cornea as
confirmed by biomicroscopic examination of the cornea and anterior chamber.
No intraoperative or postoperative complications were observed. MSCL
use improved the patient comfort and reduced the burden on surgical staff
and facilities. All analyzed parameters showed statistically significant differences
pre- and post-CXL: Sph.Eq. p = 0. 018 (Median: -2.50; Average: -2.52);
SimK-m p = 0. 006 (Median: 47.92; Average: 45.56). CDVA p = 0. 012 (Median: -0.45; Average: 0.42). Conclusion: The MSCL is a safe and efficacious device
for riboflavin delivery during CXL. The present study permits slit lamp observation
of anterior chamber flare to confirm riboflavin penetration, and
provides added safety and comfort for the patient and convenience to healthcare
providers by optimizing the use surgical facilities and staff. Keratometric,
visual and refractive results were similar to those reported in the literature for
CXL with manual riboflavin instillation. Additional studies with larger numbers
of patients are needed to confirm the study findings.