Diagnosis of Acquired Punctal Stenosis Using Anterior Segment Optical Coherence Tomography

(B)Examination:

1. External examination: should be done to rule out causes of watering other than punctal stenosis (facial palsy, lacrimal pump failure, swelling in lacrimal sac area and regurge test)
2. Slit lamp examination: for tear meniscus, lid margin, conjunctiva and punctual orifice
3. Fluorescein dye disappearance test: performed with a drop of 2% fluorescein in lower conjunctival sac, patient is instructed not to wipe the eyes. After 5 minutes, presence of staining in the tear film is assessed with cobalt blue filter.
4. Probing and lacrimal syringing, if patent confirms punctal stenosis to be the cause of epiphora rather than block in the lower lacrimal drainage system.
5. Anterior segment optical coherence tomography examination (AS-OCT) for the lower punctum: measuring the outer puntcal diametre, inner punctal diameter and punctal depth.

Examination of the lower punctum was performed using Spectral Domain OCT machine; RTVue model-RT100 CAM system (Optovue Inc., Fremont, CA, USA) version 6.2, by attaching the cornea/anterior module lens (CAM). CAM lens has a wide-angle, high-magnification lens of 10 mm working distance. The axial resolution was 5 μm, and the lateral resolution was 8 μm. The scan beam has wavelength of 840 ± 10 nm. The two red external illumination (light emitting diode ) LED on headrest were approximated on each side of the lower punctum for proper illumination and imaging of the punctum. Gentle eversion of the medial part of the lower lid was performed to expose the lower lid punctum, so the vertical canaliculus was brought to be at an axial plain without undue stretching or pressure to the lower lid. Line scan was the used examination scan, containing 1020 A-scans/line, and is 8mm in length.

Measurements of the external punctal diameter, internal punctal diameter, and punctal depth were performed on the B-scan image of the lower punctum (by selecting it from the Review window), using distance measurement tool. External punctal diameter was measured as a line connecting highest points on the medial and lateral punctal walls. Internal punctal diameter was measured as a horizontal line just above the narrowing. The distance between the line representing the external punctal diameter and the floor of the punctum was calculated and referred to the punctal depth

Results:

Data wil be collected and statistically analysed