(1)
St. Johns, FL, USA
(2)
Helen Keller Foundation for Research and Education, International Society of Ocular Trauma, Birmingham, AL, USA
(3)
Consultant and Vitreoretinal Surgeon, Milos Eye Hospital, Belgrade, Serbia
(4)
Consultant and Vitreoretinal Surgeon, Zagórskiego Eye Hospital, Cracow, Poland
The selection of the type of vitrectomy method is one of the decisions that belong to the second level of strategic planning (see Sect. 3.1).
17.1 The “Standard” Approach: Microscope and BIOM
This is how the vast majority of surgeons perform the vast majority of their vitrectomies:
Three ports (sclerotomies) are used.2
A fourth, or even fifth, one may be used for additional (“chandelier”) lightning.
The two, superior “working sclerotomies” are for the light pipe (typically in the surgeon’s nondominant hand) and for a working instrument3 (typically in the dominant hand).
The tools are switched between the hands if required by the actual situation.4
A third sclerotomy is created, usually inferotemporally,5 for the infusion cannula.
Intraocular access is provided transconjunctivally,6 via cannulas that are introduced at the beginning and removed at the end of surgery (see Chap. 21).
The surgeon views the entire surgery by looking into the eyepiece of the microscope.
Almost all of the procedure in the posterior segment is done using the BIOM or a planoconcave contact lens.7
17.2 The Slit-Lamp Approach
The microscope can be equipped with a slit illuminator, bringing the benefits, and some of the disadvantages, of the optical slit. The slit light makes the microscope act like a biomicroscope.
Two ports are needed: one for the infusion and one for the working instrument; there is a single working instrument inside the eye.
If the situation requires it, a third port can be added for a second working instrument.
The illumination angle is ~6°.
The surgeon views the entire surgery by looking into the eyepiece of the microscope.
Most of the procedure is viewed through a three-mirror lens.
Fine perimacular manipulations are viewed using a planoconcave contact lens.
A “hybrid” approach is also possible, combining a wide-angle-viewing corneal contact lens with the slit lamp: it provides for a larger field.8
The advantages and disadvantages of the slit lamp/microscope are listed in Table 17.1.
Table 17.1
The advantages and disadvantages of the slit lamp/microscope
Advantages | Disadvantages |
|---|---|
Illumination as an optic cut allows visualizing details that would remain invisible or barely visible with traditional lighting, for example: Glass IOFB in the cornea Posterior capsule/anterior hyaloid face Fine details of the structure of the vitreous and the VR interface Cellophane maculopathy | The field of view is very small compared to wide-angle viewing. The surgeon has excellent resolution at the actual worksite (which is illuminated), but no feedback about what is happening elsewhere. For example, the far end of a subretinal membrane can tear the retina as it is being pulled, but the surgeon’s visual field is limited to the area immediately surrounding the retinotomya |
Bimanual surgery is readily available if a third sclerotomy is prepared | The light reflex from the corneal contact lens is bothersome |
If only one working instrument is inside the eye, the surgeon’s nondominant hand is free to do other tasks: Scleral indentation Adjusting the contact lens’ position Stabilizing the working instrumentb (see Fig. 2.1) | If only a single working instrument is inside the eye,c it is much more difficult to stabilize the globe; this is especially a risk if the patient is under local anesthesia and the akinesia is not absolutely perfect |
Reduced risk of phototoxicity |
aAkin to a person with advanced glaucomatous damage or retinitis pigmentosa. At the bus stop he can discern the number of the arriving bus, but the recognition that a bus is arriving is partly deduced from nonvisual sources (noise, memory, fellow would-be-passengers’ change in behavior etc.)
bWith the nondominant hand’s fingers.
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