Before performing dacryoendoscopy, the puncta must be dilated (Fig. 13.3). Using an astringent solution, the passage is irrigated gently and the endoscope is inserted via the upper or lower canaliculus. The endoscope is advanced forward as far as possible to reach the stenosis or the inferior turbinate. It is then retracted, allowing for a complete evaluation of the lacrimal passage. Retracting and advancing the endoscope with simultaneous irrigation requires a certain amount of practice to obtain quality images. An unobstructed view demonstrates the normal anatomic sequence of transcanalicular endoscopy, showing canaliculus, lacrimal sac, nasolacrimal duct, and nasal mucosa of the inferior turbinate.

The canalicular mucosa appears white and is quite different from the reddish color of the mucosa of the lacrimal sac. The nasolacrimal duct can be recognized by its narrow shape and its reddish color. The nasal cavity is an intensively red structure, with a smooth surface and large width (Fig. 13.4).

Endoscopy permits differentiation of abnormal findings such as membranes, scars, acute or chronic mucosal inflammation, and foreign bodies. Even small blood deposits on the mucosa resulting from manipulation of the lacrimal passage are obvious (Fig. 13.5).

From the results of the endoscopy, an appropriate operative procedure can be selected. In Germany, some centers have performed more than 10,000 endoscopic procedures. Injuries caused by the endoscope are comparable to other surgical interventions of the lacrimal passage, such as irrigation or intubation. In general, it is possible to perform a dacryoendoscopy with anesthetizing eye drops, irrigation of the lacrimal passage with 4 % cocaine solution, and an anesthetizing nose spray. Most endoscopy procedures are performed under general anesthesia.

In children under the age of 2 years, a purely diagnostic dacryoendoscopy should only be performed in exceptional cases, because the small diameter of the lacrimal passage increases the risk of injury. Diseases of the lacrimal system in newborns and infants are mainly deformational in nature and in these cases, endoscopy does not provide any essential information. Only in cases of failure after prior procedures will endoscopy with simultaneous endoscopic therapy be performed to attempt to avoid a pediatric dacryocystorhinostomy (DCR).

The desire for lacrimal surgery without scars led to the endonasal DCR technique. Over the years, diverse modifications have been developed. The introduction of microscopes and flexible nasal endoscopes were valuable contributions to this field. The combined approach of anterograde imaging and illumination of the lacrimal system with simultaneous endoscopically controlled nasal surgery provided excellent results [11]. To minimize operative trauma, these endonasal techniques were supplemented by the use of various lasers such as Holmium, potassium titanyl phosphate (KTP), or carbon dioxide.

The KTP laser is a very powerful solid-state laser and provides a maximum energy of 10 W, delivered by a 0.3-mm semiflexible fiber that can be connected to an endoscope. The energy released from it is sufficient for creating holes in bones [12]. This laser has been used in a small number of patients and is not frequently used at this time.

A modified, miniaturized erbium:YAG laser [9, 10, 13] often used for glaucoma surgery has been in use since 1996 (Fig. 13.6). A 375-μm sapphire fiber delivers at most 50 mJ with 1–3 Hz.

The erbium:YAG laser is a photoablative laser, and its maximum absorption occurs in water. Mucosal cells have a water content of 77 % so ablation results quickly, but the main effect on a stenotic lacrimal passage is the resulting cavitation blister and not tissue ablation. This blister can extend over several millimeters, allowing for punctal stenoses to be opened with just a few pulses. The energy penetrates the tissue for only a few microns and its low thermal effect creates small necrosis zones of 10–20 μm, making it unsuitable for ablation of bone.

After changing the diagnostic probe from a two to a three working-channel handpiece, therapeutic interventions could be performed. Since 1996, an additional short tip of 4 cm has been developed for treating canalicular stenoses (Fig. 13.6c).

Initially, a diagnostic endoscopy is performed using the same probe, Vitroptic T (Fig. 13.6), before the laser application takes place. The procedure is continued until free irrigation without resistance is present and the endoscopic image confirms an opening of the mechanical stenosis. Then, bicanalicular intubation using a silicone tube is performed for preventing postoperative adhesions of the mucosa. The tube stays in place for at least 3 months. Alternatively, in cases of isolated canalicular stenosis, a monocanalicular probe can be used according to the methods of Bernard and Fayet [9]. The postoperative therapy is the same as following bicanalicular intubation in other cases.