ACTA OPHTHALMOLOGICA 64 (1986) 251-253 Technique for testing the patency of laser iridotomies Anders Heijl and Olle Holm Department of Ophthalmology (Head: Olle Holm), University of Lund. Malmo Allmanna Sjukhus, Malmo,Sweden Abstract. With laser iridotomy it may often be diffi- cult to achieve total penetration of the iris, particularly in very light or very dark irides. It may be impossible to determine with the slit-lamp whether a small laser irido- tomy is functionally penetrating. We describe a stra- ightforward method to test iridotomies for aqueous flow patency. Transcorneally introduced fluorescein is used to delineate any aqueous bulk flow from the posterior to the anterior chamber. Key words: iridotomy - iridectomy - iontophoresis - glaucoma - laser. Argon laser iridotomy as a treatment in narrow angle glaucoma was first described about a decade ago (Abraham & Miller 1975; Khuri 1973). The method has become increasingly popular because it is almost free from post-operative complications and can be performed as an outpatient procedure. However, the described surgical endpoint of the procedure, i.e. the existence of a truly penetrating iridotomy, may be hard to demonstrate conclusi- vely. Generally, one wishes to create an iridotomy which is large enough to permit visualization of the anterior lens capsule through the opening. This may be difficult to achieve, particularly in light blue irides. If, in such cases, more laser energy is app- lied, the only visible result may be increasing stro- ma1 shrinkage towards the site of the burn. Thus, one may be left with an unsatisfactory situation of uncertain iris penetration. A positive transillumination test is no evidence of true pene- tration since sparsely pigmented stroma may re- main even though the pigment epithelium has disappeared. There is clearly a need for method to ascertain patency procedures. a more affirmative in laser iridotomy Method In 1966 Holm & Krakau described a photogram- metric method for determining the rate of aque- ous flow through the pupil (Holm & Krakau 1966; Holm 1968). This method, in simplified form, can be applied also to the problem of ascertaining iridotomy patency. Fluorescein is introduced into the anterior chamber through transcorneal iontophoresis (complete details in Holm 1968). The cornea is anaesthetized by 0.4% Oxybupro- caine@applied topically. An electrode consisting of small piece of sterile cotton wrapped around the sharp tip of a metal foreign body instrument soaked in 2% fluorescein sodium is connected to the negative pole of a 4.5 volt dry battery. The pointed cotton part of the electrode is gently applied to the corneal surface 1 mm from limbus at the 6 o’clock position while the patient is holding in his hand an indifferent electrode con- nected to the positive pole of the battery. A 0.5 mA current is allowed to pass through the system for 3 min. This procedure creates a corneal flu- orescein depot (Fig. l), from which dye diffuses into the anterior chamber. Even distribution of the dye throughout the anterior chamber is achieved by having the patient move the eyes rapidly for a few seconds. 25 1