ENDOSCOPIC TRANSNASAL SURGERY FOR LACRIMAL OBSTRUCTION

Abstract

Numerous theories exist to explain tear transport which indicate the complexity of the mechanism. No one concept is entirely satisfactory. Various opinions exist to explain which part or parts of the tear conducting channels and which phase of lid movements are most essenti41 for the conveyance of tears. One concept is that the tear sac is compressed on lid closure leading to its evacuation, and on lid opening the sac expands and the tears are sucked into the canaliculi. The opposite view to this is that contraction of the orbicularis expands the tear sac, and sucking tears. Relaxation of the muscle leads to elastic contraction of the lacrimal sac, and its evacuation. This study comprised fifty-eight cases (eighty-six sides) that attended • to the Ophthalmologic and/or Otolaryngologic out-patient's clinics at Kasr El-Aini, and/or Madinet Nasr Hospitals during the period from November 1993 to May 1996. They were divided into four groups; healthy, diseased

(epiphoric), endoscopic DCR, and external DCR :,rroups. The endoscopic DCR group included small and large fistula procedure, and the external DCR group comprised those with or without silicone rod tubing. In this study pressure changes within the lacrimal sac were recorded in

• the four groups during blinking, forced blinking, nasal respiration, side to side eye movement, and Valsalva's maneuver. This was done by means of a metal cannula inserted into the lacrimal sac and the pressure tracings were recorded by a transducer-amplifier-recorder system. In healthy individuals, air bubbles and saline reflux from the non­ cannulated punctum were noticed after saline injection into the lacrimal sac. There was no sac swelling and saline was immediately tasted in the mouth. The pressure in the sac rapidly increased, then rapidly returned to zero.