October 2008

 

CATARACT/ IOL

 

Understanding risk


by Matt Young EyeWorld Contributing Editor

   
Herpes zoster in an HIV patient; complex confounding conditions like HIV can impact cataract surgery outcomes Source: Daljit Singh, M.D.

Many cataract surgeries are routine and uneventful, but knowing which eyes are high risk saves a lot of trouble when trouble arises. Parikshit Gogate, M.D., head, Department of Pediatric Ophthalmology, HV Desai Hospital, Pune, India, recently reviewed high-risk eyes and found some interesting points, especially because some risk factors will be more common depending on where you are. “Depending on where you are in the world, certain ‘high-risk’ eyes will be more common: for example, pseudoexfoliation in Somalia and India, onchocerciasis in Sudan, and angle-closure glaucoma in Asia,” Dr. Gogate reported in the March 2008 issue of Community Eye Health. “You will get to know your local problems as you perform more operations.”

Trouble spots The prevalence of HIV/AIDS, according to The World Factbook published by the Central Intelligence Agency, was 0.6% as of 2003. In South Africa, it was 21.5%. That probably makes some difference for surgeons doing cataract surgery. “Cataract surgery in these patients requires routine (and thus proper) care,” Dr. Gogate wrote. “However, such patients may have posterior segment complications such as cytomegalovirus (CMV) retinitis, vasculitis, and choroiditis, which may not be evident in a white cataract. Performing a B-scan may not always be helpful, but it should be done when fundus details are not clear. These patients are also prone to secondary infection.”

Dr. Gogate also had some suggestions about pseudoexfoliation, which he noted is more common in Somalia and India. “Pseudoex-foliation causes weak zonules and glaucoma,” Dr. Gogate reported. “There is an increased chance of zonular dialysis.”

As for glaucoma itself, Dr. Gogate had the following warnings and recommendations: • Eyes with long-standing glaucoma have poor endothelial cell counts; post-op corneal edema may occur. • Eyes that have been treated for many years with anti-glaucoma agents, like pilocarpine, may have pupils resistant to dilation. • Complications like iris injury, capsular tear, and zonular dialysis can aggravate pre-existing glaucoma. Previous trabeculectomy means that the functioning bleb must be preserved during cataract surgery by using either a corneal incision (phacoemulsification) or a temporal approach. To complicate matters, synechiae and a shallow anterior chamber are often present.

Onchocerciasis, which Dr. Gogate noted is common in Sudan, affects the cornea, uvea, and retina. “In endemic areas, cataract surgery can be disappointing due to optic nerve and retinal pathology,” Dr. Gogate warned. “You must take care when selecting patients for cataract surgery, in order to avoid performing operations which will bring no benefit to patients.”

Uveitis patients will be troublesome. “Uveitis causes synechiae and cataract,” Dr. Gogate reported. “Posterior synechiae can be gently separated using an iris repositor after instilling viscoelastic. This will probably mean that you will perform a ‘can-opener’ capsulotomy. The sphincter pupillae may still need to be stretched. Keep iris handling to a minimum in cases of uveitis, at it may trigger postoperative inflammation. It is advisable to start oral and local steroids a few days before surgery.”

Considering all risks

In order to minimize cataract surgery risks, Dr. Gogate suggested performing a thorough eye examination which includes a fundus exam, treating any and all eye infections, and considering potential visualization problems.

“A blocked and infected lacrimal sac may cause endophthalmitis,” Dr. Gogate noted. “It is extremely important to check the sac patency before surgery. If the sac has mucoid regurgitation, instill local antibiotic drops and postpone surgery. A dacryocystectomy (DCT) or dacryocystorhinostomy (DCR) may be done if antibiotics do not resolve the condition before surgery is to take place.”

Visualization problems could include corneal opacity and a small pupil. And of course, you might encounter a difficult cataract. “It is also important to have available all the equipment you may need to manage a possible complication. For example, surgeons should have a vitrectomy machine in the case of capsular rupture and vitreous loss,” Dr. Gogate reported. Nonetheless, John Sheppard, M.D., professor of ophthalmology, microbiology, and immunology, Eastern Medical School, Norfolk, Va., suggested that there are almost too many high-risk eyes before cataract surgery to define them all. “That could be a long list,” he said. He added the following to Dr. Gogate’s list: patients with chronic ocular surface disease, previous surgery, and retinal disease, among others. Nonetheless, he was adamant that you can almost always perform cataract surgery in such eyes. “You can absolutely proceed with surgery,” Dr. Sheppard said. “It just requires more preparation.” Dr. Gogate, in his report, added: “Before the operation takes place, it is good practice to explain to such patients that a poor outcome is a possibility. This makes these patients’ expectations more realistic and improves postoperative compliance and follow-up. In most cases, patients who are blind with complicated cataract will be happy with even a modest improvement of their vision.”

Editors’ note: Dr. Gogate did not indicate any financial interests related to this study. Dr. Sheppard has no financial interests related to his comments.

Contact information

Gogate: parikshitgogate@hotmail.com
Sheppard: 757-622-2200, docshep@hotmail.com

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