Three days after uneventful phaco to her right eye, a 70-year-old woman returned to the emergency clinic complaining of blurred vision. She had good results on the first postoperative day, but the vision in her right eye deteriorated over the next 48 hours.
UCVA was counting fingers, but it pinholed to 20/60. The eye was white and quiet with a normal intraocular pressure (IOP) and clear media. Slit-lamp examination comparing the affected eye with her other pseudophakic eye is shown (Figure 1), together with a comparative B-scan ultrasound (Figure 2).
What is the diagnosis and preferred course of action?
Amar Agarwal, FRCS, FRCOphth
An early postoperative decrease in vision is a serious complication and could be caused by a variety of conditions (eg, endophthalmitis, uveitis, increased IOP). In this case, a close look at the patient's slit-lamp image (Figure 1) shows a decreased anterior chamber depth in the right eye when compared with the left. Additionally, the B-scan of the right eye (Figure 2) shows an anteriorly vaulted IOL lying in close apposition to the posterior surface of the iris. Since the IOP is normal, we assume that it is not causing a pupillary block.
I would diagnose this patient with early capsular blockage syndrome (CBS). CBS occurs when the edges of the capsulorrhexis adhere to the IOL optic and cause a build-up of liquid in the closed compartment of the capsular bag. This liquid build-up pushes the optic forward. CBS can occur intraoperatively1 (ie, nucleus drop following excess hydrodissection) and in early2 or late postop.3-5 (ie, CBS with liquefied aftercataract presenting as opalescent fluid behind the IOL). Postoperative osmotic distension might be due to retained viscoelastic, cortical matter, or even from the epithelial cells.
Management options for postoperative early CBS include Nd:YAG laser anterior capsulotomy or removal of retained viscoelastic or cortical matter, if present. Delayed CBS may be treated with Nd:YAG laser posterior capsulotomy to release the fluid in to the vitreous, after excluding the possibility of Propionibacterium acnes endophthalmitis. Surgical posterior capsulotomy with anterior vitrectomy is rarely performed for this complication.
If Nd:YAG laser anterior capsulotomy does not resolve the condition, the etiology is likely due to retained viscoelastic—assuming that a thorough cortical clean-up was performed. If so, the viscoelastic from behind the IOL should be removed.
Cyres K. Mehta, MS(Ophth), FASCRS
Pseudophakic CBS was first described in 1989.6,7 This syndrome typically occurs when a large optic IOL is implanted into a capsular bag with a curvilinear capsulorrhexis that is smaller than the diameter of the lens. Retained viscoelastic material, lens epithelial cells, and their proteinaceous byproducts create an oncotic pressure in the bag. This pressure draws aqueous into the bag while the margin of the IOL seals the capsular bag. There is documentation of a surgery that uses sodium hyaluronate as a viscoelastic.8 In that case, the material in the capsular bag was mainly hyaluronan that had drawn water in along an osmotic gradient.
Jamie Zacharias, MD, postulated that saccadic movements that reach speeds of 1000º per second may lead to the inflow of aqueous into the capsular bag.9 A glue-like matter causes the capsule to adhere to the anterior IOL margin and creates a one-way valve effect, keeping the fluid in the bag.
Typically, the IOL is pushed forward in the bag and makes the anterior chamber shallow. This shallowness may be either obvious or imperceptible. The anterior movement of the IOL in the bag creates a myopic shift, and the patient experiences a decreased UCVA after day 1. As noted in the B-scan (Figure 2) there is a space between the posterior margin of the IOL and the posterior capsule, which is darker in the right eye. Additionally, the slit-lamp examination (Figure 1) shows slight turbidity of the fluid. Even though the pressure is presently normal and the eye is white, the situation may rapidly change and IOP may spike. Peripheral anterior synechiae and circumcorneal congestion may also develop.
The management options in this case are (1) peripheral Nd:YAG laser iridotomy, (2) full dilatation of the pupil and then anterior Nd:YAG capsulotomy, or (3) posterior Nd:YAG capsulotomy. Peripheral Nd:YAG iridotomy, however, is frequently not peripheral enough and is therefore obstructed by the lens. The fluid may also be viscid and resist leaking out. The second option of anterior Nd:YAG capsulotomy has to be peripheral enough to work. If you choose this method, the pupil should be adequately dilated.
A posterior Nd:YAG capsulotomy is the simplest approach. With this method, the fluid will escape into the vitreous and the chamber will deepen as the IOL moves posteriorly. The myopic shift will disappear, and the vision will rapidly improve.
David Teenan, FRCS(Ed), FRCOphth
In this case, the slit-lamp examination (Figure 1) shows an enlargement of the space between the posterior capsule and the IOL optic with shallowing of the anterior chamber. The B-scan ultrasound (Figure 2) shows anterior displacement of the IOL optic and iris diaphragm with a shallow anterior chamber when compared with the unaffected eye.
In view of these findings, I would diagnose this patient with capsular bag distension syndrome (CBDS). This rare complication follows phacoemulsification and may present with the above-mentioned features as well as induced myopia. Retained viscoelastic material has been implicated as the main causative factor of CBDS. This is because the viscoelastic supports lenticular epithelial cells, which in some cases then proliferate to form a slightly cloudy suspension. The viscoelastic also creates an osmotic gradient across the capsular membrane, and as a result, symptoms only develop after the viscoelastic equalized its osmolality with the surrounding vitreous and aqueous.
There are several management options available in cases of CBDS. Spontaneous resolution has been reported, but in observational cases, there were occurrences of angle closure glaucoma, chronic uveitis, and posterior capsule opacification. Treatment with anterior Nd:YAG capsulotomy has been advocated for CBDS. This treatment, however, may release the viscoelastic into the anterior chamber and result in an acute rise in IOP. The Nd:YAG laser may also be used to perform a posterior capsulotomy to release the contents into the vitreous cavity. Some centers use surgical aspiration, although this exposes the patient to the risks of another intraocular complication (eg, endophthalmitis).
In this case, my preferred option would be to perform a Nd:YAG posterior capsulotomy, as releasing the contents of the capsular bag into the vitreous has minimal complications.
In all cases, prevention is better than a cure, and care should be taken to aspirate all the viscoelastic at the end of cataract surgery.
Amar Agarwal, FRCS, FRCOphth, is Director of Dr. Agarwal's Group of Eye Hospitals, in Chennai, India. He states that he has no financial interest in the products or companies mentioned. Dr. Agarwal may be reached at +91 44 2811 6233; dragarwal@vsnl.com.
Cyres K. Mehta, MS(Ophth), FASCRS, is a consultant ophthalmic surgeon and Director of Mehta International Eye Institute, in Mumbai, India. He states that he has no financial interest in the products or companies mentioned. Dr. Mehta may be reached at cyresmehta@yahoo.com.
David Teenan, FRCS(Ed), FRCOphth, is a consultant ophthalmologist for Ayr Hopsital, in the United Kingdom. He did not provide financial disclosure information. Dr. Teenan may be reached at david.teenan@aaaht.scot.nhs.uk.
Larry Benjamin, DO, FRCS, FRCOphth, is in the Department of Ophthalmology at Stoke Mandeville Hospital, in Aylesbury, UK. He is a member of the CRST Europe Editorial Board. Dr. Benjamin may be reached at larry.benjamin@btopenworld.com.
Brian Little, MA, DO, FRCS, FRCOphth is an ophthalmologist at the Royal Free Hospital in London. Dr. Little is a member of the CRST Europe Editorial Board. He may be reached at brianlittle@blueyonder.co.uk.
Up Front | May 2007
Early Postoperative Blurred Vision
Amar Agarwal, FRCS, FRCOphth; Cyres K. Mehta, MS(Ophth), FASCRS; and David Teenan, FRCS(Ed), FRCOphth Section Editors: Larry Benjamin, DO, FRCS, FRCOphth and Brian Little, MA, DO, FRCS, FRCOphth
