Endoscopy to aid anterior segment surgery
Moore JE1,2 and Sharma A2
1Department
of Ophthalmology, Royal Victoria Hospital, Belfast, Northern Ireland
2Department
of Ophthalmology, Bedford Hospital, Bedford, UK
Correspondence to: Mr A. Sharma, Department of Ophthalmology, Bedford Hospital
(South Wing), Bedfordshire, MK42 9DJ. UK.
Email asharma263@hotmail.com
Accepted for publication: 1st August 2003
Endoscopy to aid anterior segment surgery. Voice narrative accompanies the video. |
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Introduction
Corneal surgery is being transformed through lamellar surgical techniques with the aim to improve recovery times, decrease astigmatism and reduce postoperative inflammation. With these newer techniques combined cataract surgery may pose greater technical difficulty including the challenge of a poor view of the anterior chamber through an opaque cornea. A potentially useful technique to counter the poor surgical view may be endoscopy.
Endoscopy has been increasingly used in surgical disciplines other than ophthalmology. Successful use of new ocular surface lenses however, has limited the eagerness to investigate the full potential of endoscopy to assist with intraocular surgery. To date ophthalmologists using endoscopy for intraocular surgery have been principally confined to the glaucoma or vitreo-retinal surgical specialty, to allow proper visualisation of the ciliary body region or assist with the repair of traumatic posterior segment damage1. However, endoscopy can also provide enhanced visualisation of intraocular structures where ocular surface opacity obscures the intraocular view.
In this video presentation, we demonstrate a continuous curvilinear capsulorrhexis (CCC) via an endoscopic technique. In addition, we demonstrate the obvious benefits of endoscopy to assist in deep lamellar corneal surgery and speculate on its potential to revolutionise posterior corneal surgery.
Methods
Four whole globes consented for research were obtained from the Florida eye bank. Three 2.0mm stab incisions into the anterior chamber were made 120 degrees apart at the limbus in each of these eyes to allow access for a endoscope and other instruments. Vision blue was used to stain the capsule. Under visualisation from the endoscope, a cystatome connected to a viscoelastic filled syringe was inserted into the anterior chamber and used to initiate a CCC. The CCC was then completed using capsular forceps. The endoscopic view of the anterior chamber and lens capsule was sufficiently clear to allow initiation and completion of a CCC despite an overlying opaque cornea.
A further 4 whole globes were obtained, an endoscope was introduced into the anterior chamber through a 2mm limbal incision. A 26 gauge needle was then introduced into the cornea with the bevel down. The needle was placed as deep as possible within corneal stroma adjacent to Descemet’s membrane. Air was then injected to attempt to strip Descemet’s membrane from posterior corneal stroma. Once air was injected the cornea became totally opaque. The endoscopic camera was again used to visualise the posterior corneal surface during this procedure and further repeated air injections were made in an attempt to produce an adequately sized air bubble.
Comments
Where cataract and corneal opacification occur in unison, usually a "triple procedure" is advocated with trephination and removal of the diseased cornea, an "open top" cataract extraction procedure with intraocular lens placement prior to completion of the penetrating keratoplasty. Renewed research into corneal lamellar surgery and refinement of techniques in anterior and posterior lamellar keratoplasty 2 have generated interest in developing techniques to treat cataracts without an "open top" technique.
The videos’ shown demonstrate the potential value of endoscopy to assist with cataract and anterior segment surgery. The anterior capsule is easily seen supported by the underlying cataractous lens after staining with a capsular dye (vision blue). The CCC procedure therefore does not require stereoscopy for its safe completion. As cataract surgeons recognise however, venturing further into the lens substance, results in loss of monocular clues to depth and stereopsis becomes an important requirement to allow safe cortex removal from the thin moveable posterior capsular membrane. In the future endoscopy may be used to complete cataract surgery where overlying corneal opacity prevents adequate vision. This will only occur with further development of endoscopic systems which allow adequate stereoscopic vision 3.
Recently, Anwar & Teichmann 2 reported the use of air bubble dissection as an advantageous technique to achieve maximum corneal stromal dissection depth during anterior lamellar surgery. They used an air bubble dissection technique to produce a smooth corneal dissection plane and to minimise the risk of Descemet’s/endothelial layer perforation. To achieve adequate dissection of Descemet’s membrane from posterior corneal stroma requires a large bubble of air at the appropriate site. An opaque overlying corneal stroma will preclude adequate surgical view to determine whether air bubble dissection has been completed. As demonstrated the video, endoscopy enhances visualisation of the posterior corneal surface and allows proper assessment of whether or not adequate Descemet’s membrane dissection has occurred to enable completion of surgery.
Acknowledgements
The authors would like to thank Mr J Wallace,
Computing Science University of Ulster, Mr J Mairs, and Mr P McMullan, School of
Media and Performing arts, for their technical assistance with preparation of
the digital video.
References