April 2016

 

EW CATARACT

 

Cataract surgery and small pupils


by Matt Young and Gloria Gamat EyeWorld Contributing Writers

 
   

The femtosecond laser

The femtosecond laser-assisted nucleus fragmentation pattern in an eye with a small pupil Source: William Trattler, MD

How FLACS could be used for small pupil cataract surgery

Cataract surgery in eyes with small pupils (less than 6 mm in diameter) is more surgically challenging due to the comorbidities involved and the higher complication rates associated with it.Comorbidities could include uveitis, hard lenses, glaucoma, pseudoexfoliation, zonular dehiscence, and floppy iris syndrome, said William Trattler, MD, Center for Excellence in Eye Care, Miami, at the 2015 American Academy of Ophthalmology (AAO) annual meeting.

Small pupils may lead to smaller than desired capsulotomy diameters, causing capsule contracture and a posterior shift of the implanted intraocular lens (IOL), reported Ina Conrad-Hengerer, MD, Ruhr University Eye Clinic, Bochum, Germany, and colleagues in the September 2013 issue of the Journal of Cataract & Refractive Surgery.1 A smaller than desired capsulotomy or a poorly constructed capsulotomy, either extending to the equator or having an anterior radial tear, is associated with an increased risk of intraoperative and postoperative complications, Dr. Trattler said.

Hence, the benefits of the precision and safety achieved with laser cataract surgery apply directly to these patients, Conrad-Hengerer and colleagues said. Small pupils must, therefore, be taken into account with femtosecond laser-assisted cataract surgery (FLACS).

Along came FLACS In recent years, FLACS has made a buzz in the cataract surgery arena and brought along with it promising results. Surgeons hope to reduce the amount of phaco energy required and reduce the risk of complications, which could eventually lead to better visual outcomes in patients. In a 2011 review of FLACS procedures, Moshirfar and colleagues reported in the Middle East African Journal of Ophthalmology2: It is possible that in the coming years, femtosecond lasers will revolutionize the way we perform cataract surgery. The method has already shown excellent results for precise and self-sealing corneal incision, highly circular, strong, and accurate capsulorhexis, and safer and less technically difficult phacofragmentation and subsequent phacoemulsification, said Majid Moshirfar, MD, professor of ophthalmology and co-director, cornea and refractive surgery division, Department of Ophthalmology, University of California, San Francisco.

But even FLACS has its limitations. For instance, the fact that femtosecond lasers are in the near-infrared wavelength contributes to their limitation. For example, the femtosecond laser cannot penetrate through central corneal opacities. As well, when the pupil is small, the femtosecond laser imaging system cannot visualize through the iris, and the laser cannot penetrate through the iris, Dr. Trattler said. Therefore, Dr. Trattler noted, small pupil size interferes with both anterior segment imaging and femtosecond laser delivery. Because FLACS relies on anterior segment imaging for laser pattern mapping, any patient with poor dilation would be a poor candidate, confirmed Moshirfar and colleagues. Such patients would include those with posterior synechiae, intraoperative floppy iris syndrome suspects, or those on chronic miotic medications. Patients with phacodonesis and zonular dialysis, or even those with risk factors such as pseudoexfoliation syndrome or trauma, may not be ideal candidates, they said.

Successful FLACS in small pupil cases

While FLACS may enable enhanced precision and safety in eyes undergoing cataract surgery and IOL implantation compared to conventional phacoemulsification, it requires adequate dilation for imaging and treatment. It cannot treat posterior to opaque or pigmented ocular tissue, such as the iris, Dr. Trattler said. Reporting their study findings on small pupils and cataract surgery in a recent issue of Current Opinion in Ophthalmology,3 Hashemi and colleagues stated: Femtosecond laser cataract surgery systems require optical imaging, targeting, and laser delivery, and a small or irregular pupil can impede anterior capsulotomy and nucleus fragmentation. When the pupil size is smaller than the intended capsulotomy size despite intense topical application of mydriatics, the surgeon faces a major challenge at the start of the surgery, said Hassan Hashemi, MD, Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran.

Dr. Trattler and colleagues evaluated the safety and efficacy of FLACS using the LENSAR laser system (LENSAR, Orlando, Florida) in a retrospective chart review that included 32 consecutive patients (13 females and 19 males) with small pupils (less than 6 mm diameter) and a mean age of 76+8.3 years. After 3.4 months of follow-up, 53.3% of eyes had UCVA of 20/40 or better, and 84.2% of eyes had BCVA of 20/40 or better. No patient reported any intraoperative or postoperative complications.

In our study, all eyes with a mean pupil size of 5.2+0.24 mm had successful cataract extraction and IOL implantation using the LENSAR laser system after using preoperative topical mydriatics, Dr. Trattler reported. In cases of insufficient pupil dilatation despite preop use of topical mydriatics, Dr. Trattler said, intracameral pharmacologic agents and surgical techniques (i.e., intracameral mydriatics, viscoadaptive agents, and pupil expansion rings), which have been described for small pupils with manual phaco, can be applied in the setting of FLACS with excellent results. Laser-assisted femtosecond cataract surgery with the LENSAR laser platform was safe and effective in our patient cohort with small pupils, he concluded.

References

1. Conrad-Hengerer I, et al. Femtosecond laser-assisted cataract surgery in eyes with a small pupil. J Cataract Refract Surg. 2013;39:13141320.

2. Moshirfar M, et al. Femtosecond laser- assisted cataract surgery: a current review. Middle East Afr J Ophthalmol. 2011;18:285291.

3. Hashemi H, et al. Small pupil and cataract surgery. Curr Opin Ophthalmol. 2015;26:39.

Editors note: Drs. Trattler, Moshirfar and Hashemi have no financial interests related to their comments.

Contact information
Hashemi: hhashemi@noorvision.com
Moshirfar: Majid.Moshirfar@ucsf.edu
Trattler: wtrattler@gmail.com

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