Double-Capsulorhexis Approach to the Intumescent White Cataract
(Scroll down for the surigcal video of the Capsulorhexis x 2 Technique)
The intumescent white cataract poses challenges during many different steps of surgery. This begins in the pre-operative period where biometry is compromised by the completely opaque media and continues into surgery where the absence of a red reflex decreases visualization. But probably the most important step of surgery is creation of the capsulorhexis which is difficult due to the pressure gradient created by a fluid-filled capsular bag.
During the initial exam, the entire ocular system must be examined carefully, particularly if there is a history of trauma. A shallow anterior chamber depth in the presence of a normal axial length could indicate zonular laxity. Wrinkling or fibrosis of the capsule could indicate capsular damage which could lead to rupture and displacement of the nucleus into the vitreous cavity during surgery. The presence of sensory exotropia may be noted in cases of a longstanding intumescent white cataract, which can cause diplopia after surgery.
With no view of the posterior segment, an ultrasound B-scan can be used to get a gross image of the retina and vitreous cavity. Optical coherence biometry will not likely be fruitful due to the opaque media, so an ultrasound A-scan can be used to measure the axial length. If data from the fellow eye is used for lens calculations, consider adding 0.5 to 1.0 diopters to the lens power so that you will err on the side of residual myopia.
Setting patient expectations is important because these cases have a higher risk of complications with less accurate lens power estimation and a greater likelihood of ametropia. Usually, these patients are very understanding and appreciative since anything, even a complicated case with a 20/100 outcome will be better than their current vision which tends to be very limited.
The use of trypan blue dye is a must in these cases to stain the anterior capsule to aid in visualization during creation of the anterior capsulorhexis. The primary issue is the pressure created within the capsular bag due to the liquified cortex material. If the anterior chamber pressure is lower than the intra-lenticular pressure, there will be a forward force exerted on the anterior capsule during capsulorhexis creation. This will rapidly cause an uncontrolled radialization of the capsulorhexis which can extend to the posterior capsule, leading to a dropped nucleus and vitreous prolapse. The key to managing this is to keep the anterior chamber pressure higher than the intra-lenticular pressure during capsulorhexis creation.
Using a femtosecond laser to perform the anterior capsular opening can be useful since it can be accomplished in a closed eye in just a few seconds, but that is a very expensive option (a femtosecond laser can cost more than US$500,000 with additional costs per use). We can also achieve success using simple, manual instrumentation. In the case presented here (Figure 1), two small paracentesis incisions are created, each being less than 1 mm in width. This small size is important to pressurize the anterior chamber after the anterior capsule has been stained with trypan blue dye. We avoid making the primary phaco incision at this point because it is much larger, about 2 to 3 mm in width. This large incision will depressurize the anterior chamber and the intra-lenticular pressure will be too high in comparison.
Via the small paracentesis, a 25g bent needle cystotome is used to create a small, round capsular opening (Capsulorhexis #1). This round configuration is important since it will not radialize or rip uncontrollably. At this point we can make the main phaco incision with a diamond keratome and insert the phaco probe. Through this small capsular opening, the probe is used to aspirate out the fluid from the capsular bag. Touching the nucleus and rocking it gently will ensure that any fluid behind the nucleus also is aspirated.
Above: Figure 1 (A) The cystotome is used via a 1-mm or smaller paracentesis incision to create a small round capsulorhexis in the anterior capsule while the anterior chamber is highly pressurized. (B) The diamond keratome is used to make the main incision, which will lower the anterior chamber pressure. (C) The phaco probe is placed within this small capsulorhexis to aspirate out the milky, liquified cortex, thereby reducing the intra-lenticular pressure. (D) Now the forceps can be used to create a normal, 5-mm capsulorhexis without fear of radialization.
With the intra-lenticular fluid removed, the pressure in the capsular bag is very low and we can now create our larger, 5-mm diameter opening (Capsulorhexis #2) without fear of inducing the Argentinian Flag Sign which occurs with a radially split capsule which gives the blue-white-blue appearance of that flag. With successful completion of the 5-mm capsulorhexis, the nucleus can be removed using the phaco-chop technique. With the dense nucleus, a mechanical disassembly of the nucleus using the chop technique can reduce the ultrasonic energy and help preserve corneal endothelial cells. The lens implant is inserted into the capsular bag and the case is completed without issues.
Above: Figure 2 (A) The capsulorhexis is completed without issues. (B) The dense nucleus is removed using the phaco-chop technique. (C) The single-piece IOL is injected into the eye. (D) The optic is securely held with 360 degree overlap of the capsulorhexis over the optic.
These patients have an immediate increase in vision, though final healing can take weeks to months. There may be prolonged inflammation due to dispersion of lens proteins during surgery and the amount of ultrasonic energy used during the procedure. If sensory exotropia was present, these patients may initially describe diplopia which tends to resolve spontaneously in most patients. There may also be a residual refractive error which can be addressed with spectacles or further procedures.
Patients with opaque, white cataracts tend to be our most appreciative since we have taken them from literal blindness to excellent vision in the course of a brief and safe surgery.
All text, figures, pics, and videos are © 2018 Uday Devgan MD.