Following Hydrodissection, the Iris Is Prolapsing and the Globe Is Very Firm. How Should I Proceed?
Following hydrodissection, the eye suddenly becomes very firm and the iris prolapses. In this situation, one must highly suspect that it was the hydrodissection itself that caused the problem; however, it is necessary to rule out other sources.
External forces have to be considered and are quickly assessable. If injection anesthesia has been used, there could be an orbital hemorrhage. This can be ruled out easily by gentle displacement of the globe to show that the orbit is indeed not firm. The lock mechanism on the speculum could suddenly have released, resulting in partial closure of the lid with forcing of the speculum blades against the globe, or the patient’s lids may be strong enough to overcome the less firm opening of the wire-lid speculums. In addition, anything that can lead to Valsalva’s maneuvers must be considered. Pain, extreme anxiety, cough or cough suppression, and a full bladder causing the patient to strain are all possible causes. Each of these Valsalva’s maneuvers can lead to impairment in venous drainage from the globe and the orbit. Communicating with the patient immediately by asking what is wrong and recommending normal breathing can quickly alleviate this problem.
Intraocular sources of pressure must be considered. A choroidal effusion or a suprachoroidal hemorrhage will frequently be detected by either a loss of red reflex or by a dark shadow appearing within the red reflex. A fundus contact lens in the operating microscope, or an indirect ophthalmoscope, can be used to immediately assess the posterior segment of the eye and rule in or out this diagnosis. If the eye is extremely firm and the view is poor, one may wish to proceed rapidly with a B-scan. Generally, there is increasing data that a sclerotomy does not alleviate the problem but may exacerbate the problem with excessive bleeding increasing the danger to the eye.
The most likely cause in the present situation, however, is overhydration during the course of hydrodissection. Cortical cleaving hydrodissection is a maneuver that I first described in 19911 and involves tenting the anterior capsule with a cannula peripheral to the capsulorrhexis margin and gently injecting fluid into the capsular bag external to the cortex. The fluid goes around the lens and becomes loculated in the capsule behind the lens as the fluid reaches the forniceal capsular-cortical connections, which disallow its emergence from the retrolenticular space. This is observable by a forward movement of the lens, which makes the capsulorrhexis enlarge. The hydrodissection should be stopped at that point and the cannula should depress the lens posteriorly, which would increase intracapsular pressure and force posteriorly loculated fluid to come forward around the equator of the lens, rupturing the capsular-cortical connections and flowing out of the capsulorrhexis. This is observed by an immediate return to the previous, smaller size of the capsulorrhexis, as well as radial striations on the anterior surface of the lens as cortical fibers are washed centrally. In order for the cortical cleaving hydrodissection to work, there has to be an intraoperative capsular block syndrome, which is cured by decompression of the capsule by downward pressure on the lens.
In the instance in which the eye is firm and the iris is prolapsing, the hydrodissection cannula should be used through a paracentesis to decompress the lens, while at the same time exerting pressure on the posterior lip of the paracentesis incision to allow egress of fluid and viscoelastic. Once that is done, the hydrodissection cannula can be used through the same paracentesis to sweep posterior to the internal lip of the incision to reposit the iris (Figure 19-1). Additional help in repositing the iris may be gained by using a dispersive viscoelastic through the wound after releasing fluid pressure from behind the prolapsed iris through the paracentesis.
Figure 19-1. The hydrodissection cannula is used through the same paracentesis to sweep posterior to the internal lip of the incision to reposit the iris.
If decompression of the lens does not result in softening of the eye, it is highly likely that hydration of the vitreous occurred during hydrodissection. This can occur if there is some loss of zonular integrity or if the capsule has in some way been compromised with injection of the fluid directly into the vitreous space. In many cases, you can patch the eye and have the patient wait in the holding area for a few hours and the problem will resolve. In more difficult cases in which the iris prolapse cannot be controlled, you may need to proceed with a limited vitrectomy. I prefer a 25-gauge transscleral vitrectomy through a sutureless incision that is less than 1-mm, 3.5 to 4.0 mm posterior to the limbus or the use of a sharp needle on a 2-cc syringe through the sclera in the same location to draw off a few tenths of a milliliter of vitreous fluid at a time. The transscleral vitrector must be used with caution because the eye can become inordinately softened very quickly. Continuous, tactile tamponade of the globe as the vitrector is being used to monitor intraocular pressure should help avoid over-softening of the eye. Once the eye is softened adequately, further attempts at hydrodissection should not be made. Hydrodelineation can be done with less than 0.2 mL of fluid with depression of the posterior lip of the incision in order to allow egress of viscoelastic and fluid. The endonucleus should be rotatable within the epinucleus and removed, after which the epinucleus and cortex can be removed without further risk to the eye.
1. Fine IH. Cortical cleaving hydrodissection technique includes cortical cleanup. Ocular Surgery News. 1991;9:24,26-27.