Ocular Surface Optical Coherence Tomography For Imaging Contact Lens And Ocular Surface

Abstract

 

Purpose:

 

To develop an ocular surface optical coherence tomography (OS-OCT) for imaging the ocular surface and tear film underneath the edge of contact lenses (CL).

 

Methods:

 

The system features custom spectrometer powered with a light source with 188 nm bandwidth at the center wavelength of 870nm (T870, Superlum). The calculated depth resolution is 1.6µm in tissue. The measured scan depth was 1.42 mm and speed was 24K A-line per-second determined by the CCD line camera. A telecentric light delivery system and video viewing system were co-axially aligned and mounted with a standard slit-lamp. The ocular surface of one eye on 5 normal subjects (3 males and 2 females) was imaged while wearing contact lenses. The tear film and epithelium underneath the lens (PureVision, Bausch & Lomb) on the peripheral region of the cornea were imaged and the dimension was measured. A drop of OCT scatter enhancer (Soothe XP, Bausch & Lomb) was placed on the concave side of the lens before insertion for tracking the tear exchange underneath the lens over a 5-minute period.

 

Results:

 

The tear film gap and epithelium (EP) around the peripheral cornea and limbus were clearly visualized (Fig). After image correction, the tear film gap on the peripheral cornea was 14 ± 9 µm thick and 1361 ± 451 µm long on 5 eyes. The tear film gap on the limbus was 30 ± 10 µm thick and 858 ± 662 µm long on 3 eyes. The scatter intensity of the tear film gap underneath the lens edge first increased within 1 min then decreased afterwards.

 

Conclusions:

 

This is a pilot study demonstrating the OS-OCT specifically for imaging the tear film, tear exchange and epithelium underneath the lens edge. This novel system will enable studying contact lens induced ocular surface compression and localized pressure underneath the lens. Further development in robust software for automatic image correction may improve the system for clinical studies.  

 

Keywords: contact lens