On Postoperative Day 1, the Anterior Chamber Is Shallow and the Patient Is Unexpectedly Very Myopic. What Should I Do?
Luther L.
Fry,
MD
The differential diagnosis for this problem is relatively short and includes wound leak, choroidal hemorrhage or effusion, aqueous misdirection, and capsular block (Figure 39-1). A wound leak is by far the most likely cause of a shallow chamber.
Figure 39-1. Differential diagnosis for shallow chamber and myopic shift.
A wound leak is relatively easy to detect. If the intraocular pressure (IOP) is near zero there is probably a wound leak. I use the Seidel test to confirm the leak. On the rare occasion where a wound leak is detected with a positive Seidel test, with either a shallow or normal depth anterior chamber, I usually take the patient back to the operating room and place an “X” suture (Figure 39-2). This is easily done under topical anesthesia and only takes a couple of minutes. The patient tends not to view this additional step as a complication or a “re-do.” I use a full sterile set-up and drape, but I have in the past done this in the office minor surgical room with a lid speculum, gloves, and no drape.
Figure 39-2. “X” suture.
With a formed anterior chamber and a wound leak, you could also consider either observing the patient or placing a bandage contact lens. These options would be useful if going back to the operating room is difficult such as when the operating room is in a hospital setting and a minor surgery room is not available in your office. However, in our surgicenter, placing a suture is almost as easy as placing a bandage contact lens. As mentioned above, the patient does not view it as a re-intervention. When we previously did surgery in the hospital, placing a suture was a major production, requiring re-admission, lots of patient anxiety, and extra expense. Suturing is certainly a more definitive treatment and spares both the patient and the surgeon any further anxiety. This is my preference if it can be done easily. However, I think the risk of endophthalmitis in this setting is very low and a couple days of watchful waiting is reasonable.
If the chamber is shallow, the incision is Seidel negative, and the IOP is normal to slightly elevated, it is possible that a choroidal effusion or hemorrhage has occurred. Indirect ophthalmoscopy or B-scan ultrasound should demonstrate the presence of a choroidal effusion or hemorrhage. Watchful waiting and careful observation can suffice for smaller choroidals, but if the choroidal is large enough to cause a shallow chamber, drainage may be necessary. Choroidals will very rarely occur with uncomplicated small incision surgery. In my personal experience, choroidals following cataract surgery were more common with the large incision planned extra capsular surgery I did years ago, and fortunately they have become pretty much a thing of the past with modern small incision surgery.
Interestingly, I think wound leak in the first few minutes following surgery may be more common than we would like to think.1,2 I recently did a study with 50 consecutive uncomplicated cataract surgeries where I measured IOP with a tonopen immediately after the speculum and drape were removed. Twenty-six percent (13 out of 50) of these patients had an IOP of 5 mm Hg or less. Prior to finishing the case I had filled the anterior chamber to a high pressure by tactile finger estimation, then I used my typical technique to express fluid through the side-port incision to what I estimated to be a mid-teens pressure. Interestingly, by 3 hours to 5 hours later when I did my same day check, none out of the 50 patients had an IOP less than 10, and 50% were above 25. (Yes, I do remove viscoelastic.) Although immediate wound leak may occur, it is likely in the living eye that these leaks quickly seal (so cadaver studies may need to be discounted with this disclaimer).
These transient wound leaks are, of course, a concern because they may increase the risk of postoperative bacterial endophthalmitis.3 By being alert to possible wound leaks and suturing them promptly when they occurred, I have been fortunate to have had no cases of endophthalmitis for the past 5000 cataract operations.
If the chamber is shallow and the IOP is elevated, one may either have pupillary block or aqueous misdirection. Pupillary block with a posterior chamber intraocular lens (IOL) is very rare and I have not seen this despite not making an iridotomy in over 30,000 cases. Fortunately, I have also have had no personal experience with postcataract surgery aqueous misdirection. If confronted with this, I would probably first do a laser iridotomy. If the chamber did not immediately deepen, I would try to get through the peripheral capsule with the YAG back into the vitreous. If still not successful, I would open the posterior capsule and disrupt the anterior vitreous. If successful, I would keep the patient on atropine for a prolonged period of time. If not successful, I would refer the patient to a vitreoretinal surgeon for a core vitrectomy. If ready access to a vitreoretinal surgeon is not available, one might first try vitreous aspiration with a #20 or #22 needle through the pars plana.
Capsular block syndrome would also be a possible cause of a myopic shift due to a more forward location of the IOL optic. This may or may not be associated with shallowing of the anterior chamber. The most frequent cause is retained viscoelastic behind the IOL optic. The diagnosis should be obvious by observing the distended posterior capsule behind the IOL. I have also not personally seen this early on, although mild degrees are quite common several years postoperatively. Some cases of capsular block syndrome will resolve spontaneously. A peripheral YAG opening in the anterior capsule can allow enough trapped fluid to exit the capsular bag to allow the IOL to move posteriorly. Finally, removing the retained viscoelastic in the operating room remains a last resort if other measures fail.
Late capsular block syndrome, noted incidentally when the patient comes in for his or her YAG laser capsulotomy several years after surgery, is common. It is obvious at slit lamp, with the distended space between the IOL and posterior capsule filled with turbid fluid. It goes away immediately after YAG laser capsulotomy and is not associated with any excessive iritis post-YAG. Late capsular block syndrome is not usually associated with any shallowing of the anterior chamber or refractive power changes.
Immediate postoperative hypotony and shallow chamber with the accompanying myopic shift are aggravating; however, they need not be disastrous. For leaking incisions, immediate suturing under topical anesthesia, or careful monitoring, possibly after placement of a bandage contact lens, can rescue these rare situations without permanent damage to anything but the surgeon’s coronaries.
References
1. Fry EL. Immediate postoperative intraocular pressures after routine topical clear corneal cataract surgery. Free paper presented at: ASCRS Symposium; March 19, 2006.
2. Taban M, Sarayba MA, Ignacio TS, et al. Ingress of India ink into the anterior chamber through sutureless clear corneal cataract wounds. Arch Ophthalmol. 2005;123:643-648.
3. Nagaki Y, Hayasaka S, Kadoi C, et al. Bacterial endophthalmitis after small-incision cataract surgery. J Cataract Refract Surg. 2003;29:20-26.