CASE PRESENTATION
A 54-year-old white male consulted me regarding decreased vision in his left eye that affected his ability to drive at night. The patient's ocular history included a complicated cataract extraction in his right eye that had required anterior vitrectomy and placement of an anterior chamber IOL 1 year earlier. He had no family history of cataracts, and he denied both a history of congenital cataracts and any current use of medications. The patient had a history of asthma and had been prescribed short courses of oral prednisone several times.
The patient's UCVA was 20/30 OD and 20/80 OS, and he had a BCVA of 20/20 OD and 20/50 OS. Slit lamp examination showed clear corneas in both eyes. The anterior chamber lens in his right eye was well positioned with no evidence of vitreous prolapse into the anterior chamber. The crystalline lens of his left eye showed 1+ cortical spoking, with 2+ diffuse, ground-glass posterior subcapsular changes and a denser central posterior capsular opacity. The opacity did not seem to be contiguous with the posterior capsule, nor was there a clearly defined space between the two. There was no evidence of pseudoexfoliation. The patient expressed concern about the lengthy postoperative course in his fellow eye and sought assurance regarding the potential outcome of cataract surgery in his left eye.
HOW WOULD YOU PROCEED?1. How would you diagnose the lenticular changes in the patient's left eye?
2. How would you counsel the patient regarding the risks of surgery?
3. How would you alter your surgical procedure to minimize complications?
SURGICAL COURSE
In addition to cortical and posterior subcapsular cataract (PSC), the patient's eye exhibited the findings of a posterior polar cataract. Polar cataracts are usually congenital and noted upon routine examination as a visually asymptomatic, incidental finding. When nuclear or PSC changes also begin to affect the lens, patients may present to an eye care specialist due to changes in their visual acuity. In many cases, physicians misidentify a polar cataract as a PSC. The characteristic features of a polar cataract include a more focal location and greater density as compared with a PSC (Figure 1).
The main intraoperative concerns with a polar cataract are (1) unusually firm adherence of the cortex and/or polar cataract to the posterior capsule and (2) the presence of an occult posterior capsular defect or dehiscence. In these cases, overpressurization of the anterior chamber or capsular bag, aggressive hydrodissection, and/or aggressive nuclear rotation during surgery may result in a posterior capsular rupture. I have found it helpful at the slit lamp to attempt to identify the presence of a clear space between the polar opacity and posterior capsule, because this gap may indicate less corticocapsular adhesion in that area. No such clear zone was identifiable in this patient. I informed him that the presence of a polar cataract conferred a greater risk of intraoperative complications, especially in light of the surgical course in his fellow eye.
Large polar cataracts may be associated with greater defects in the posterior capsule. Some surgeons have advocated planned extracapsular cataract extraction or even pars plana lensectomy in such cases. Because the polar opacity in this case was small, I opted to perform phacoemulsification in the patient's left eye. I created my standard 5- to 6-mm continuous curvilinear capsulorhexis, which I find allows for safe phacoemulsification and the stable placement of an IOL in the ciliary sulcus, if necessary. Then, I followed the nuclear mobilization technique described by I. Howard Fine, MD, of Eugene, Oregon, and his colleagues.1 I inserted the hydrodissection cannula under the anterior capsule at multiple locations and injected BSS (Alcon Laboratories, Inc., Fort Worth, TX) gradually and with a uniform velocity until the fluid wave approached the edge of the posterior opacity. Once fluid surrounded the opacity, hydrodelineation allowed me to identify the endonucleus, which I rotated carefully.
Because the patient lacked significant nuclear sclerosis, I was able to perform uneventful phacoemulsification using a low bottle height and vacuum and relying primarily on aspiration to remove the soft endonucleus. After completing the removal of the endonucleus, I slowly introduced viscoelastic under the anterior capsule in order to separate the cortex and epinucleus from the capsule. In general, I use a bimodal setting for epinuclear removal, because it allows the linear control of aspiration. I used a bimodal setting in this case but with slightly lower vacu um settings (100 vs 200 mm Hg). I carefully engaged and entirely removed the epinucleus. Cortical cleanup can be problematic in a case such as this one, because there may be firm adhesion between the polar cataract and capsule. Generally speaking, I find it best to leave the central cortical material until the end of the case due to the chance of capsular rupture. I do not hesitate to leave behind a mild central opacity and then perform an Nd:YAG capsulotomy 3 months postoperatively. In this case, as I stripped the cortex centripetally, adequate separation between the posterior capsule and cortex enabled me to remove the entire central cortex without incident. It is important at any time during the case, but especially at this stage of the operation, for surgeons to be prepared to deal with a breach in the posterior capsule.
In many cases of polar cataract, the opening in the capsule is round, and, after careful vitrectomy, the surgeon can place a lens within the bag. After cortical removal, this patient's posterior capsule was intact, and I inserted an acrylic posterior chamber IOL into the capsular bag.
OUTCOME
Postoperatively, the patient had a plano refraction and 20/20 UCVA at 3 months.
Posterior polar cataract is a condition that may lead to significant intraoperative ocular morbidity. Accurate preoperative recognition of this entity, coupled with careful surgical technique, will help decrease the likelihood of intraoperative complications and ensure a good visual outcome.
1. Fine IH, Packer M, Hoffman RS. Management of posterior polar cataract. J Cataract Refract Surg. 2003;29:16-19.
