Cheryl Guttman Krader, BS, Pharm

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Lisa B. Arbisser, MD, explains why primary posterior optic capture should be routine in cataract surgery and describes her technique.

Hyaloid-Sparing primary posterior optic capture 

should one day be routine in cataract surgery

 because it enables patients to maintain the best possible vision with a one-time only procedure, according to Lisa B. Arbisser, MD.

“Posterior optic capture with IOL haptics in the bag and the optic prolapsed through a posterior capsulotomy into Berger’s space allows a clear visual axis for life even when done in the pediatric age group without anterior vitrectomy and in all adults, truly turning cataract surgery into a premium procedure,” said Dr. Arbisser, adjunct professor, Moran Eye Center, University of Utah, Salt Lake City.

This technique reduces retinal straylight produced by the “clear” posterior capsule, resulting in better initial vision, she added. The technique “eliminates risk of secondary visual degradation from posterior capsule opacification (PCO) and therefore the need for planned anterior vitrectomy in children and hyaloid busting Nd:YAG laser posterior capsulotomy in adults,” Dr. Arbisser said.

“It obviates the need for a square-edged optic because the square edge is only necessary to retard PCO when the IOL is in the bag,” she added. In addition, it can also eliminate the dysphotopsia that is related to the square-edge design. As another benefit, it brings predictability to the effective lens position by reducing or eliminating lens epithelial cell fibrosis and contraction and eliminates the risk of postoperative rotation when using a toric lens, Dr. Arbisser noted.

Performing posterior optic capture involves some extra time and skill, but the added time is minimal, just about 1 to 2 minutes, and the learning curve is not too challenging, Dr. Arbisser noted. Surgeons should expect to perform about 150 cases to reach the expert-level, she added.

“Transitioning from extracapsular cataract extraction to phacoemulsification was a gigantic learning curve, but learning to do a posterior continuous curvilinear capsulorhexis for posterior capsule optic capture involves a minor addition to skills already mastered for anterior capsulorhexis,” she explained.

“The main hurdle may be more of a mental block, as we were always taught not to break the posterior capsule at all costs,” she added. The best cases to offer posterior optic capture initially are for patients who cannot sit for a Nd:YAG laser capsulotomy and require general anesthesia for cataract surgery, Dr. Arbisser said.

“This is the cohort that benefits the most from one surgical procedure providing permanent clarity of vision for life,” she said.

Describing her technique-taught to her by Rupert Menapace MD, Vienna, Austria-Dr. Arbisser said that after cataract removal and placing an 

 in the sulcus, she uses a 30-gauge needle positioned bevel up to lift the 5-Î¼m thick posterior capsule from the anterior hyaloid and create a posterior capsule flap initiating the rhexis.

Then, a cohesive OVD is injected through the posterior capsule opening to push the hyaloid posteriorly and make Berger’s space real.

“The OVD remains in Berger’s space, which is the space between the posterior capsule and the anterior hyaloid, and in the sulcus, creating a planar area to work in with the anterior and posterior capsules ‘pancaked’ together,” Dr. Arbisser said. Performing the posterior capsulotomy is not difficult, but compared with doing an anterior capsulorhexis, it requires that surgeons use higher magnification, a little more centripetal force, and more frequent regrasping because of the elasticity of the posterior capsule.

“There is no tendency for the tear to run out, because there is no convexity to the posterior capsule, the tear obeys the vector force applied to it,” Dr. Arbisser said. The anterior capsulorhexis is used as a guide to make a 4- to 5-mm round opening.

The anterior capsulorhexis should always be confirmed as capturable before attempting the posterior rhexis as it is the “safety-net rescue” and can be used for anterior capture from the sulcus or reverse optic capture from the bag in the event of an unsuccessful posterior continuous curvilinear capsulorhexis (PCCC) or tear during posterior capture, Dr. Arbisser said.

is completed, the capsular bag is inflated by placing OVD into the bag fornix. Though a single-piece lens is used by some surgeons-and in the United States, it is sometimes needed because the case involves a multifocal or toric IOL-Dr. Arbisser prefers a three-piece implant because the risk of late vitreous prolapse could be greater with the single-piece lens.

“The IOL should ideally have a sharp optichaptic junction that will help assure the capture and minimize IOL-lens epithelial cell interaction,” she added.

Rather than pushing on the optic 90° away from the optic-haptic junction to “pop” the optic into position, Dr. Arbisser said it may be necessary to “walk” the instrument along the optic slightly toward the optic-haptic junction on either side of 90° to ensure a good capture from junction to junction and the ideal football appearance of the captured PCCC edge for the thinner posterior capsulorhexis.

The posterior optic capture technique was first described by Howard Gimbel, MD, in 1990. Nearly 30 years later, there is ample evidence in the literature that supports its safety.

“Opening the posterior capsule does not compromise the integrity of the barrier between the front and the back of the eye because the two compartments are really separated by the anterior hyaloid, and there is ample proof the two chambered eye remains intact,” Dr. Arbisser said.

“There are more than 60 peer-reviewed papers about posterior optic capture by multiple authors,” she said. “Per data from fellow eye prospective controlled trials and experience in more than 5,000 routine patients, it does not increase the incidence of postoperative cell and flare, cystoid macular edema, retinal detachment, or IOP increase, either early or late.”

Long-term studies should logically show decreases in these and other pathologies as the hyaloid is stabilized for life and need never be disrupted by Nd:YAG laser posterior capsulotomy.

Dr. Arbisser is also studying a new idea of her own called hyaloid-sparing double capture (HSDC) wherein the IOL haptics are placed in the sulcus and the optic captured through both anterior and posterior capsulotomies into Berger’s space with undisturbed hyaloid.

“HSDC may address the incidence of late bag-lens-subluxation in addition to eliminating PCO, both of which are unfortunate sequelae of today’s standard cataract surgery,” she concluded.

This article was adapted from Dr. Arbisser’s presentation at the 2018 meeting of the American Academy of Ophthalmology. Dr. Arbisser is a consultant for Mynosys and is a minor stockholder in the company.

Articles

Approach enables patients to maintain best possible vision with one-time only procedure

Primary posterior optic capture offers many advantages in cataract surgery

Understanding the genetic cause for PPCD is becoming increasingly important and relevant in all medical fields, including ophthalmology.

Researchers studying families affected by posterior polymorphous corneal dystrophy 4 (PPCD4) have identified new mutations causing the rare autosomal-dominant corneal endothelial dystrophy. The discovery and related investigations that are described in a recent publication [Liskova P, et al. Am J Hum Genet. 2018;102:447–459.] provide insight into the molecular basis of PPCD and have implications for both clinical care and genetic researchers, said Alison Hardcastle, PhD, and Petra Liskova, MD, PhD.

Studying individuals from a Czech family and using linkage analysis, the investigators identified a single locus mapping to chromosome 8q22.3–q24.12. Through whole-genome sequencing, a unique variant (c.20+544G>T) was found in the locus that was within intron 1 of GRHL2.

Targeted screening of GRHL2 regulatory regions in individuals from unrelated, previously unsolved PPCD4-affected families led to the discovery of two additional unique genetic variants in the intronic regulatory region of GRHL2. In vitro tests showed that the three PPCD4 variants induced increased expression of GRHL2.

Histological evaluation and immunostaining studies of corneal tissue from a PPCD4-affected eye and unaffected controls showed that endothelial cells in the diseased eyes inappropriately expressed GRHL2 as well as epithelial markers (E-cadherin and cytokeratin 7), indicating that the cells had transitioned from an endothelial to an epithelial-like cell type.

Dr. Hardcastle and Dr. Liskova explained that the mutations discovered in patients with PPCD4 and those found previously in PPCD1- and PPCD3-affected families all involve genes that are key regulators of pathways involved in epithelial to mesenchymal transition/mesenchymal to epithelial transition (EMT/MET) pathways.

“An imbalance in transcription factors involved in the EMT/MET pathways appears to be a convergent disease mechanism leading to dysfunction of the endothelial barrier and the development of PPCD,” said Dr. Hardcastle, professor of molecular genetics, UCL Institute of Ophthalmology, University College London, London. “The mutations cause either an increase or decrease in expression of the transcription factors that causes the cells to transition to an epithelial-like cell state.”

Dr. Hardcastle and Dr. Liskova noted that elucidation of the genetic causes for PPCD has several clinical ramifications.

“Traditionally, disorders leading to corneal opacity have been treated surgically, and knowledge of the underlying molecular causes has not been considered essential for patient management,” said Dr. Liskova, associate professor, Departments of Ophthalmology and Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University, Prague, Czech Republic. “However, understanding the genetic cause is becoming increasingly important and relevant in all medical fields, including ophthalmology.”

Dr. Liskova noted that in some patients, PPCD is phenotypically indistinguishable from congenital hereditary endothelial dystrophy.

“The ability to identify disease-causing mutations would facilitate an accurate diagnosis. Because congenital hereditary endothelial dystrophy may be associated with hearing loss, it is recommended that affected children undergo regular evaluations of auditory function. This type of follow-up is not needed for children with PPCD,” said Dr. Liskova.

There are also implications for counseling of patients with PPCD.

Dr. Liskova explained, “Patients with both Mendelian disorders and complex disorders seek genetic counseling and testing. By dissecting the genetic cause of PPCD we can provide more accurate predictions of disease progression, associated risks, such as secondary glaucoma development, and if a corneal transplant may be necessary as disease progresses,” she said.

Dr. Liskova added, “Knowledge of the underlying genetic cause is fundamental to understanding disease mechanisms and facilitates genetic testing to determine if individuals are at risk of developing disease. Ophthalmologists have an essential role in informing patients and their families about genetic testing.”

Obtaining a clearer understanding of pathogenic mechanisms for disease development also opens up opportunities for identifying targeted therapies, and as an accessible tissue, the cornea is well suited for genetic treatment.

“Switching off inappropriately expressed genes could be considered as a possible therapeutic option for corneal dystrophies,” said Dr. Liskova.

“We have recently demonstrated the potential utility of a gene targeted therapy for Fuchs corneal endothelial dystrophy. We found that treating patient cells with a targeted antisense oligonucleotide reversed toxic effects caused by a mutation in TCF4. In the future, a similar type of gene-directed therapy could be applicable for PPCD.” said Dr. Hardcastle.

The discovery of the genetic cause of PPCD4 was possible because of the use of whole-genome sequencing (WGS).

“Whole-genome sequencing enabled interrogation of the entire genome rather than just the protein coding portion that is more typically and routinely investigated,” said Dr. Liskova.

Dr. Liskova and Dr. Hardcastle have no relevant disclosures

Cheryl Guttman Krader, BS, Pharm

Articles

Primary posterior optic capture offers many advantages in cataract surgery

Non-coding mutations identified as corneal endothelial dystrophy cause

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