Exploring Scleral Contact Lens Fitting Using Octa: A Cross-Sectional Study

This study aims to explore the use of Optical Coherence Tomography Angiography (OCTA) in assessing the fitting of scleral contact lenses.

Ophthalmology department at HASSAN II university hospital, SIDI MOHAMED BEN ABDELLAH university, Fez,

Morocco

In this cross-sectional study, we examined 25eyes using Anterior Segment Optical Coherence Tomography (AS-OCT) and OCT-Angiography (OCTA). AS-OCT assessed vault and scleral indentation, while OCTA measured conjunctival blood vessel density (VD) and investigated potential interruptions in conjunctival vasculature after two hours of scleral contact lens (ScCL) wear. We performed OCTA scans on the nasal surface (6x6mm) before and two hours post-ScCL application. No interruption in conjunctival vasculature or whitening was observed after scleral lens fitting. Independent observers subjectively measured limbus indentation using AS-OCT. Further analyses explored correlations between indentation value, vascular density, and vault.

The VD without ScCL was significantly higher (64.26±7.86) than the VD measured with ScCL (59.56±8.53) (p=0.01). Interruption in conjunctival vasculature was evident in OCTA images in 13cases, and VD simultaneously diminished in this group (p=0.001). In the group where no interruption of conjunctival vasculature was observed, the VD remained stable after scleral lens application (p=0.002)
No correlation was found between the value of limbal indentation and the status of conjunctival vasculature interruption (p=0.65), or with the value of VD (p=0.86). Additionally, the mean vault in the group with conjunctival vasculature interruption was lower compared to the group with no interruption, although this was not statistically significant (p=0.09)

Utilizing AS-OCT and OCTA, we were able to image and evaluate the ocular surface blood VD, vault, and indentation with high repeatability and reliability. This study introduces a novel application of OCTA for the investigation and monitoring of conjunctival vasculature in ScCL fitting. It suggests that a seemingly continuous conjunctival vasculature observed in slit lamp examination does not necessarily rule out the possibility of vascular interruption. Such interruptions could be revealed by OCTA and may influence future prescriptions for contact lens adapters. However, it's important to note that this process is time-consuming. This should prompt OCTA machine manufacturers to enhance the way we capture OCTA images for the anterior segment