October 2016

 

COVER FEATURE

 

Challenging and complicated cataract surgery

Achieving best outcomes with cataract surgery in the post-vitrectomized eye


by Liz Hillman EyeWorld Staff Writer

 
   
Cataract surgery
Upon insertion of the probe, the infusion pressure and lack of vitreous induce a reverse pupillary block resulting in an overly deep anterior chamber.


The chopper is used to temporarily tent up the iris to break the pupillary block and equalize the pressure between the anterior and posterior chambers.


The surgeon can now proceed with cataract removal with an anterior chamber that is of normal depth.


The cataract is completely removed and the capsular bag is filled with viscoelastic in preparation for IOL insertion.

Source: Uday Devgan, MD

Awareness of a few possible complicating factors can result in successful cataract surgeries

Cataract surgery in the post-vitrectomized eye has become more common, according to Richard Tipperman, MD, Wills Eye Hospital, Philadelphia. As such, there are certain preop and intraoperative considerations to take into account with these cases to ensure the safest outcomes. “Retina people have gotten much more aggressive about doing vitrectomies for early macular holes and macular puckers when the patient’s vision is dropping a bit,” Dr. Tipperman said. “The other thing is that scleral buckling is falling out of favor and more people are having vitrectomies for retinal detachments, so there are a lot more vitrectomies.” People who have had a vitrectomy, if they don’t have a cataract already, will eventually form a cataract, Dr. Tipperman added. This could be due to inflammation and/or oxygenation that occurs in the procedure, but in some more rare cases, the lens capsule is punctured from an intravitreal injection needle or a vitrector. Kevin M. Miller, MD, professor of clinical ophthalmology, University of California, Los Angeles, said more intravitreal injections are being done now, leading to a few more lens capsule punctures. “Capsule punctures produce a different cataract than you get in the typical post-vitrectomy cataract eye,” Dr. Miller said. “Even so, they are still the minority of post-vitrectomy cataracts.” In 1998, Dr. Miller was a coauthor of a study that found, for the most part, cataract surgery after pars plana vitrectomy resulted in favorable visual outcomes with “few unplanned intraoperative events or complications … .”1 Keeping up on subsequent studies that have been published in more than a decade since, Dr. Miller said, aside from some studies citing more anterior chamber depth fluctuation, cataract surgery and its outcomes for the post-vitrectomized eye are “about the same as they would be for an average eye.”

Consider timing

Timing of a cataract can say a lot in cases with retinal pathology. If a patient received an intravitreal injection for age-related macular degeneration, for example, and 4 days later developed a very mature or rapidly progressing posterior subcapsular cataract, this could indicate that the lens was touched by the needle, Dr. Tipperman said. Uday Devgan, MD, clinical professor of ophthalmology, University of California, Los Angeles, said the typical cataract that forms after an uneventful vitrectomy has central nuclear sclerosis and takes months or longer to develop. “If the patient develops a white cataract within a few weeks of the pars plana vitrectomy, there is almost certainly an iatrogenic break of the posterior capsule, and if this patient undergoes cataract surgery, there is a high risk of the entire lens nucleus falling onto the retina,” he said. Timing is a factor in the scheduling of the cataract surgery itself as well. As a retinal specialist, Ehsan Rahimy, MD, Palo Alto Medical Foundation, Palo Alto, California, says he typically advises patients to wait at least 3 months after routine vitrectomy before proceeding with cataract surgery, unless circumstances warrant sooner intervention (i.e., intraoperative lens touch causing a rapidly progressive white cataract). After that time, most healing from the underlying retinal pathology has usually occurred, and other mitigating visual factors have resolved (i.e., gas bubble has dissolved, scleral buckle has settled into place, intraocular inflammation has been treated) to where an accurate assessment can be made about whether cataract surgery is warranted as opposed to an updated refraction.

In some cases, such as a severe retinal detachment with proliferative vitreoretinopathy (PVR) where silicone oil endotamponade was utilized, Dr. Rahimy said he would recommend waiting at least 3 months and in some cases 6 months or even longer before removing the oil. “In these situations, once we determine the oil is ready for removal, the retinal surgeon may perform a combination case in conjunction with the anterior segment surgeon to remove the oil and cataract together in order to minimize the number of trips to the operating room for a patient,” he said.

Preop evaluation

A careful and thorough slit lamp examination, focusing on the type of cataract and posterior capsule, can prepare surgeons for what they might encounter intraoperatively, Dr. Devgan said. White opacities, or plaques, on the posterior capsule can be points of weakness and have to be addressed for visual outcomes, he said. If the cataract is not yet dense and milky, Dr. Miller said the surgeon might be able to spot a capsule puncture at the slit lamp and prepare for that accordingly as well. Bonnie An Henderson, MD, clinical professor of ophthalmology, Tufts University School of Medicine, Waltham, Massachusetts, said that while posterior capsule integrity can be difficult to evaluate, a vertical line in the posterior aspect of the cataract can be a warning sign, and ultrasound biomicroscopy can be helpful preoperatively as well.

Then there is the possibility of zonular instability. “I compare the anterior chamber depths (ACD), measured with noncontact biometry, of the two eyes. If the post-vitrectomized eye has a longer ACD, this can signify zonular laxity,” Dr. Henderson said. Dr. Rahimy said that post-vitrectomized eyes may be prone to postop inflammation. “Many of our cataract colleagues are starting these patients on topical non-steroidal and steroidal anti-inflammatory drops before the day of their cataract surgery to preemptively address the inflammation, and have a low threshold to refer back to the retinal specialist in the postoperative period if the patient is experiencing significant inflammation (i.e., cystoid macular edema) refractory to topical therapy,” he said.

Intraoperative adjustments

As a general rule, Dr. Henderson said she avoids hydrodissection in the post-vitrectomized eye and only hydrodelineates. “I try to minimize the rotation of the lens and prefer to remove the inner nuclear core by chopping rather than rotating it in the capsular bag,” she said. Dr. Miller also said he would not hydrodissect in an eye where he suspected a capsule puncture. In such a situation, he advised pressurizing the eye with viscoelastic material before pulling instruments out of it. If zonular instability is confirmed, Dr. Miller said first and foremost the bottle height or infusion pressure should be low. He also said surgeons should be on the lookout for reverse pupillary block, which could stress the zonules if not addressed by lifting the iris. Dr. Devgan said that a single, nasal iris hook could be placed at the beginning of surgery to prevent such a block as well. Dr. Devgan said he prefers to create a large capsulorhexis (5 to 5.5 mm) and prolapse the nucleus out using hydrodissection or viscodissection, if the bag is intact. If the posterior capsule is compromised, he would lift the nucleus with a chopper. This, he said, allows him to chop it in the anterior chamber without stressing the capsule or risking an already compromised capsule.

As for dense plaques that might be present on the posterior capsule, Dr. Miller said he prefers to perform a posterior capsulorhexis at the time of cataract surgery vs. a YAG laser capsulotomy later for several reasons. First, it restores visual acuity immediately. Second, he considers it “low risk” but noted that there will likely be a small amount of vitreous left after the previous vitrectomy that will require cleanup. Third, he said his capsulotomy is large and circular; as such he would prefer not to leave a large floater in any remaining vitreous gel. Dr. Tipperman said he prefers a YAG capsulotomy over a posterior capsule capsulorhexis. The fact that some residual opacification could remain is something he prepares his patients for, telling them it will be addressed later. Taking retinal pathology into consideration is also important when selecting an IOL.

“I think most people who are conservative would recognize that if patients have had a vitrectomy for retinal detachment or proliferative retinopathy, there is a decent chance they may have more retinal surgery later down the road, and their care is going to be a lot easier if they have a hydrophilic acrylic lens in,” Dr. Tipperman said. “If the retina person needs to use silicone oil, there won’t be an issue of the oil sticking to an acrylic lens.” Dr. Henderson also said she would prefer an acrylic IOL over a silicone IOL for these reasons.

Setting patient expectations


Cataract Surgery article summary

Dr. Miller said it is especially important to set realistic visual expectations with these patients. “All of their friends have 20/20 vision; they’re all elated. These post-vitrectomy patients go in and they’re waiting for their perfect 20/20 ‘wow’ postop day 1 visit, but they had a macular hole or an epiretinal membrane in the eye, and it is important to temper their expectations so that they’re realistic,” Dr. Miller said. If a patient, for example, has a persistent or recurrent epiretinal membrane, he or she may not have noticed distortions prior to cataract surgery. “The patient may think, ‘What happened, what went wrong?’ The surgeon just made it so that the patient could see the distortion better, and now the membrane has to be peeled,” Dr. Miller said. “We have to manage expectations in this crowd of patients a little bit more than some others.”

Reference

1. Grusha YO, et al. Phacoemulsification and lens implantation after pars plana vitrectomy. Ophthalmology. 1998;105:287–294.

Editors’ note: Dr. Tipperman has financial interests with Alcon (Fort Worth, Texas) and Diopsys (Pine Brook, New Jersey). Drs. Devgan, Henderson, Miller, and Rahimy have no financial interests related to their comments.

Contact information

Devgan
: devgan@gmail.com
Henderson: bahenderson@eyeboston.com
Miller: kmiller@ucla.edu
Rahimy: erahimy@gmail.com
Tipperman: rtipperman@mindspring.com

Achieving best outcomes with cataract surgery in the post-vitrectomized eye Achieving best outcomes with cataract surgery in the post-vitrectomized eye
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