Endopinion: experts' opinions on endoscopy

Applications from cataract surgery to glaucoma and to dacryocystorhinostomy are only a prelude of things to come.

---Endoscopic probes. It is the qualitative and quantitative performance of optic fibers that provides the optical quality of the image. Thus, for a diameter of 0.95 mm, there are 10,000 fibers. Fibroscopes with 15,000 to 20,000 fibers for the same diameter already exist.

The challenge of endoscopy utilizing the most modern technologies is to do better and more in the fields of cataract, glaucoma, vitreoretinal and orbito-lacrimal surgery, and to limit the impact of surgery on the patient. Currently we are in a hybrid surgical situation, mixing traditional actions with new endoscopic procedures. But the adoption of endoscopy into ophthalmology is certain to come with new industrial developments, especially with the introduction of the endoscopic image into the operating microscope. Mixing endoscopy — the internal sagittal view — and microscopy — the traditional frontal view — allows us to manipulate endocular structures with more safety and ease than in traditional surgical approaches.

We invited some ophthalmologist experts in endoscopy to talk about their current and future endoscopic surgical applications.

Joshua Ben-Nun, MD, Tziriffin, Israel

---Rupture of the posterior capsule is the first step in a cascade of events finishing in the partial or total dislocation of the crystalline material or the posterior chamber lens. Perfect endoscopic control of the preceding phases accompanying the posterior implantation avoids a certain number of them and helps manage this complication.

I use the endoscope for any vitreoretinal surgery (retinal detachment, vitrectomy, epiretinal and subretinal surgery, lensectomy) whenever it is better to leave the anterior segment untouched due to fibrosis and vascularization. With the endoscopic technique, these cases have less fibrinous reaction and significantly lower incidence and intensity of postoperative intraocular pressure elevation. The assessment and removal of currently invisible epiretinal membranes creating macular holes are only one simple example. Assessment and accurate treatment of various conditions associated with subfoveal neovascular membranes (especially in an occult form) is another example, and so forth. The endoscope will be a complete tool, with unique capabilities that no other existing intraocular surgical method has, to enable working at optical (not digital) magnification range of up to 8003 (operating microscope magnification).

Claude Boscher, MD, Paris

Since September 1993, I have made a conscious effort to try endoscopy-assisted vitrectomy and I am now in the process of evaluating it in various conditions. I use an endoscopic probe that incorporates a video channel, a fiber optic light source and a diode laser.

The rationale for using endoscopy-assisted vitrectomy is the following:

Endoscopy provides direct anatomical visualization of the anterior zonular portion of the vitreous base and of its connection to the ciliary body, the posterior lens capsule, or the iris, around 360º, without scleral indentation, whatever the conditions of transparency of the anterior segment; tangential approach and huge magnification provide a unique evaluation of the depth and density of the vitreous fibers and their connections.

So far, I have been using endoscopy in two kinds of circumstances:

• Visualization problems as may occur in complications of cataract surgery (endophthalmitis, dislocated lens fragments or IOL, expulsive hemorrhage) or of poor pupil dilatation and/or of anterior segment opacities (detection of tiny retinal breaks);
• Risk for development of anterior vitreoretinal proliferation (some cases of rhegmatogenous retinal detachment, severe proliferative diabetic retinopathy).

In some conditions, as in trauma, both circumstances can be associated.

Development of endoscopy in ophthalmology has been delayed compared with other medical fields, first because of the need for miniaturization, and now because of the necessity of a training period, owing to video monitor control and lack of stereoscopy. Commercialization of the prototype combining endoscopy with microscopy (endoscopy under the operating microscope) would suppress the difficulties and the current reluctance.

Dominique Bremond-Gignac, MD, Paris

In our surgical experience, many procedures are performed without any visibility of the anatomic system. Endoscopy allows more precise and more anatomical surgical procedures in oculoplastic and lacrimal surgery.

In lacrimal surgery, the natural pathways are the canaliculi. Endoscopy could localize the obstruction at first and then control the technical procedure of desobstruction.

Different technical opportunities may be used: holmium YAG laser or more recently microdrill through the canaliculi and the bag. After opening the lacrimal bone with the laser or the microdrill, endoscopy can visualize the size of the hole and the correct positioning of the silicone intubation. This technique needs more follow-up, but it leaves no scar. It appears to be a quick and safe surgical procedure.

In pediatric surgery, many applications can be considered. Cataract surgery in children requires perfect cleaning of the lens, and endoscopy could check the bag over 180º. Then the lens positioning could be controlled easily, with more safety during postoperative follow-up.

Endoscopy through the binoculars of a microscope allowed reliability of different combined surgical techniques in anterior (cataract, glaucoma) and posterior (retina) segment. The technical improvement in size and definition of micro-fiber optics allows great hope for safer and more reliable surgical procedures in coming years.

Ignasi Jürgens, MD, Sant Cugat Del Valles, Spain

The applications of ocular endoscopy are based on the principles of this technique; it offers new insights into hidden structures of the eye. In my surgical practice, endoscopic techniques are used in anterior segment and vitreoretinal surgery. My first application of endoscopy was endocyclophotocoagulation of the ciliary processes for treating refractory glaucomas. We soon started to perform this surgery combined with phacoemulsification with good results.

Since 1994, my practice has become more retina oriented, and this is where I have tried to find ways in which endoscopy could improve my surgical results and reduce complications. Endoscopy-assisted transscleral fixation of IOLs allows perfect positioning of the sutures in the ciliary sulcus and avoids the main risks of closed-eye techniques: iris or ciliary body damage with subsequent intraocular bleeding.

In vitreoretinal surgery, I have found important applications in exploring the retro-iridal surface, the ciliary body, the pars plana and the pre-equatorial retina. It is especially useful in exploring anterior neovascularization in diabetic retinopathy and anterior vitreoretinopathy.

Although there is an obvious learning curve in using the endoscope, and there are specific complications of each endoscopic surgical technique, the advantages became obvious the first day I used an endoscope.

Some applications of ophthalmic endoscopy are linked to future technical improvements. To practice endoscopy, I have always used the video-endoscopic method, which has obvious drawbacks, especially alternating the view through the eyepieces of the microscope with the video screen images. Endomicroscopy (endoscopy through the operating microscope) will be a significant improvement of ophthalmic endoscopy. It will allow more precise positioning and driving of the endoscope, and will reduce complications when the surgeon changes from the microscopic image to the video screen or vice versa. Small gauge instruments and multifunctional endoscopes, especially multiport and interchangeable probes with flexible and driven tips, will allow us to perform more surgery with the endoscope.

Francisco E. Lima, MD, Goiania, Brazil

As a glaucoma specialist, I use endoscopy with laser to treat a great number of my glaucoma patients who need surgery. The main indication in my practice is in combined surgery. We developed the technique called scleral depression in combined phacoemulsification and in-the-bag endoscopic cyclophotocoagulation (ECP) as primary surgical treatment for cataract and glaucoma.

The technique consists of performing scleral depression during in-the-bag ECP, which allows us to photocoagulate the entire ciliary process. In the recent past, the only way of photocoagulating the whole ciliary process would be through a pars plana approach, which would require vitreous manipulation. In-the-bag ECP combined with scleral depression allows us to treat the whole ciliary process without entering the vitreous cavity. There is no conjunctival manipulation either. By the way, overall results after a mean follow-up of 20 months are very encouraging without the well-known complications related to filtering surgeries.

With regards to other applications of ocular endoscopy, I usually treat refractory glaucomas with ECP. I have been conducting a prospective, randomized study to compare the Ahmed implant and ECP in refractory glaucomas. Also I have performed some endoscopic goniotomies.

Likewise, ocular endoscopy has helped me in scleral fixation of secondary IOL implantation. During complicated phacoemulsification in which there is a posterior capsule rupture and lens fragments fall into the vitreous, I usually perform endoscopy-assisted vitrectomy. In eyes with refractory congenital glaucoma and opaque corneas, I have performed endoscopic lensectomy combined with endoscopic cyclophotocoagulation.

Ocular endoscopy gave me a different point of view in ophthalmic surgery. Currently, I practice endoscopy with monocular control. However, I believe that endoscopy will certainly be better performed with binocular control through the operating microscope. Then endoscopy-assisted vitrectomy and peeling of the retina, even endoscopic goniotomies and endoscopy-assisted scleral fixation of IOLs, will be accomplished with more safety and ease.

Today, I cannot imagine myself without ocular endoscopy with laser available in the operating room. In the near future, I believe nobody in the field will.

Richard Mackool, MD, New York

I have been using endoscopic diode cyclophotocoagulation since 1993. I have used this mostly in patients with controlled primary open-angle glaucoma who are simultaneously undergoing cataract-implant surgery. I also occasionally use the endoscope in order to visualize the location of implanted material, particularly subluxated IOLs, at the time of repositioning or removal. The endoscopic actions would be better controlled under the binocular of the operating microscope if a "split screen" view were possible to permit both external and internal views simultaneously.

Norman Medow, MD, New York

The introduction of endoscopy in ophthalmology offers the pediatric ophthalmologist a new surgical tool that can treat many of our most difficult problems, glaucoma being one of the most troublesome and at times refractory to conventional treatment, especially in children.

Although uncommon, congenital glaucoma is often visually disastrous. When the cornea is cloudy, goniotomy, arguably the standard treatment, is not possible. Use of the endoscope in this disorder offers us promise for future treatment.

Secondary glaucoma in cataract surgery approaches 30% to 40%. Treatment for this type of glaucoma is difficult, and varied treatments have been attempted with limited success. The use of the endoscope coupled with the diode laser to directly ablate the ciliary processes is an exciting innovation in treating this most difficult condition.

In addition to the above uses, the endoscope can be used for other purposes:

• Observation of the optic nerve head with the endoscope in patients that have cloudy anterior segments can allow us to decide whether extensive anterior segment surgery should be performed based on the observation of the posterior pole.
• Nasolacrimal duct surgery, determining the exact position of IOL implantation, and theoretical uses such as aid in finding a lost muscle after strabismus surgery, also are possible applications.

These and other innovations in ophthalmic endoscopic surgery are exciting new techniques that over the next few years will find a significant role in both pediatric and adult ophthalmic surgery.

Jean-Marie Piaton, MD, Paris

In my practice as a lacrimal surgeon, I systematically perform nasal endo-scopy at the preoperative examination, at the time of surgery and for postoperative care. I use rigid Hopkins endoscopes of 2.5 mm diameter and 30º deflection for preoperative examination that allows me to examine the middle and lower meatus. Inspection of the middle meatus is useful to detect nasal pathology and to see if the nasal fossae are large enough to achieve an endonasal dacryocystorhinostomy. Ex-amination of the lower meatus is performed to search for an abnormality of height or size of the Hasner's valve that can cause epiphora with system patent for syringing or for suppuration at the level of the Hasner's valve that is a sign of dacryoliths and also to sensitive Jones I and Jones II dye tests. To perform endonasal dacryocystorhinostomy, I use a rigid endoscope of 4 mm diameter and 0º angle that gives a larger optical field and that is less delicate than the 2 mm diameter endoscope.

Endoscopy also enables the course of healing of the nasal ostium after surgery to be studied. Granular tissue or synechiae can be removed with forceps or vaporized with the laser.

In the future, routine performance of microendoscopy of the lacrimal pathway would allow me to explore some patients, particularly when the system is patent to springing or when dacryoliths or tumors are suspected. Scars, relative obstruction and change of the mucosa could be identified more easily and could be directly opened with a laser. The microendoscopic view in the operating microscope could be useful in case of canalicular repair.

We wish to thank our scientific endoscopic collaborators for their help with this article: Daniele S. Aron-Rosa, MD, PhD (France); Yale L. Fisher, MD (USA); Karen M. Joos, MD, PhD (USA); Frank H. Koch, MD (Germany); and Bruce M. Massaro, MD (USA).

For Your Information:

• Claude S. Leon, MD, is president of the International Society of Ophthalmic Endocopy Inc. In New York. He can be reached at Ocular Endoscopic Surgery, Avenue George Pompidou, Portovecchio, 20137, France; (33) 495-706-3000; fax: (33) 495-706-293; e-mail: Leon.joseph.opht.endoscop@wanadoo.fr; Web site: perso.wanadoo.fr/endoscopy.leon/. Dr. Leon has a direct financial interest in the endomicroscope and endoscopic instruments. He is not a paid consultant for any companies mentioned in this article.
• Joseph A. Leon, MD, under a European laser certification, is working in all ophthalmic applications of laser-endoscopy.