Vanessa Caceres

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Accurate IOL measurements, proper patient selection, and solid surgical technique can help to reduce the number of IOL explantations.

Accurate IOL measurements, proper patient selection, and solid surgical technique can help to reduce the number of IOL explantations.
	
	While some IOL explantations are inevitable for cataract surgeons, with good surgical technique, accurate lens measurements, and proper patient selection and preoperative counseling, physicians can lower their explantation rate. 

, professor of ophthalmology, codirector of the 

Intermountain Ocular Research Center, director of ocular pathology, Moran Eye Center, University of Utah, Salt Lake City

, reviewed an ASCRS/ESCRS survey delving into trends regarding explanted lenses. The survey inquired about patients’ preoperative and postoperative visual acuity, any signs or symptoms and complaints, and complications that required IOL removal, exchange, or secondary intervention.
	
	Surgeons were asked about explantation of the following IOL types: one-piece, plate-type; one-piece IOLs with haptics, three-piece IOLs; multifocal IOLs, and accommodating lenses. The materials used in the lenses mentioned were silicone, acrylic (hydrophobic), hydrogel (hydrophilic acrylic), and collamer. As in previous years, the lens with the highest rate of explantation was the one-piece hydrophobic (monofocal) lens.
	
	However, this is also the most common type of lens used in the United States, which would explain why it is removed most frequently, Dr. Mamalis said. Other materials are not removed as often because they are used less often, he said. Dislocation and decentration were the most common complications associated with one-piece silicone IOLs, followed by glare/optical aberrations and incorrect lens power.
	
	Dislocation and decentration also were the most common reasons for removal of three-piece silicone and one-piece acrylic lenses, Dr. Mamalis reported. This complication is usually linked to a surgical complication or weakness in the zonules or the capsular bag, he explained.Other common reasons for lens removal among various lens types included incorrect lens power and glare/optical aberrations. Incorrect lens power still was a cause of IOL removal in the survey, but this has trended downward in recent years, leading Dr. Mamalis to say that surgeons are getting better at choosing the correct IOL power.
	
	The number of multifocal IOLs that were explanted increased over the past year, and this was most frequently due to glare/optical aberrations. Proper patient selection could help reduce the number of multifocal IOL patients requiring lens removal, he said. Calcification and opacification were the most common reasons that hydrophobic acrylic IOLs were explanted.

The trends seen in the current survey have been consistent over the past five years, according to Dr. Mamalis. In addition to solid surgical technique and appropriate patient collection, surgeons also should aim for continuous curvilinear capsulorhexis with capsular bag fixation of the IOL, Dr. Mamalis added. Quality manufacturing and careful IOL folding and insertion also are key. The ASCRS/ESCRS survey is an ongoing annual data collection; the survey related to explanted foldable IOLs is available on each society’s respective website, Dr. Mamalis said.

This article was adapted from Dr. Mamalis’ presentation at the 2019 American Society of Cataract and Refractive Surgery annual meeting. Dr. Mamalis is a consultant for Anew Optics and PerfectLens. He also does research for a variety of ophthalmic companies.

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Imaging tools-such as topography, tomography, ray-tracing, and anterior-segment optical coherence tomography (AS-OCT)-are helpful to both plan refractive surgeries and assess any potential complications, said Dr Sonia H. Yoo.

Topography can be helpful for keratoconus screening, surgical planning and astigmatism correction. It also can be used to document the effects of surgery, investigate any poor outcomes and plan for enhancements, added Dr Yoo, professor, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States. “It’s important to recognise pathological patterns to rule out candidates such as the patient with inferior steepening,” Dr Yoo said.

Keratorefractive surgery performed in such cases is associated with a higher risk of keratectasia and postoperative topographic instability.

A decentered myopic ablation and a central island are other complications that can be seen by topography and are associated with poor outcomes. Tomography generates a 3D re-creation and can measure the anterior and posterior surfaces, which can be helpful with assessment of the cornea. Wavefront maps and ray-tracing help surgeons to evaluate higher-order aberrations (HOAs), which can be responsible for reduced quality of vision, Dr Yoo said.

Ray-tracing is another tool to evaluate HOAs. Anterior-segment OCT is a non-contact approach to evaluate the cornea and anterior segment, and it can penetrate through corneal opacities and scars. One way to use AS-OCT is to see if a patient is a candidate for a LASIK enhancement.

A closer look Dr Yoo presented some example patients evaluated with these imaging tools. For instance, a 30-year-old male had LASIK and persistently blurry vision. By looking at topography and HOAs, Dr Yoo could see significant amount of coma, consistent with his complaint of blurriness.

Another patient was a 28-year-old male wanting to have refractive surgery. Dr Yoo also had treated the patient’s father, who had bilateral corneal transplants for keratoconus. The son had a spherical refraction, good best-corrected visual acuity (BCVA), and relatively normal tomography. Via wavefront, a high degree of coma was seen.

“Coma is an early finding with keratoconus and because of his strong family history, we decided to do surface ablation,” Dr Yoo said.

The patient has been happy with his result at 1-month postop and is 20/20 J1+ in both eyes.

However, he does notice some glare at night. Dr Yoo also shared the story of a female with a LASIK evaluation who had good BCVA and not much astigmatism but who also had a significant paracentral scar. Her topography was regular, but it also showed a thick cornea. Because of the ulcer and good BCVA, Dr Yoo decided to do LASIK in one eye and transepithelial PRK in the eye with the scar.

“We removed 50 Î¼m with the laser, then we did the full treatment,” Dr Yoo said. “We informed her there could be disturbances.”

However, the patient ultimately had a good outcome, she concluded.


	This article was adapted from Dr Yoo’s presentation at the 2018 meeting of the American Academy of Ophthalmology. Dr Yoo is an equity partner in Resolve Ophthalmics and a consultant for Avedro.

Author | Vanessa Caceres

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