OR WAIT null SECS
Aphakic eyes that have no or inadequate capsular support can pose a significant challenge to cataract surgeons. Careful attention to the preoperative considerations, appropriate intraocular lens choices, surgical techniques, and postoperative management can ensure optimal results.
Take-home: Aphakic eyes that have no or inadequate capsular support can pose a significant challenge to cataract surgeons. Careful attention to the preoperative considerations, appropriate intraocular lens choices, surgical techniques, and postoperative management can ensure optimal results.
Reviewed by David C. Ritterband, MD
Dr. RitterbandAphakic eyes that lack or have inadequate capsular support can pose a real challenge to cataract surgeons. The approach to these eyes has changed markedly in recent years, according to David Ritterband, MD.
Surgeons are moving away from the use of aphakic contact lenses and anterior chamber lenses, Dr. Ritterband reported, and toward the use of intraocular lenses (IOLs) that are placed precisely anatomically in the posterior chamber with fixation to the iris or sclera. He discussed the preoperative considerations and surgical management of these eyes.
Careful preoperative planning is the first step to successful exchange or replacement of IOLs. These considerations include the choice of anesthesia (peribulbar, retrobulbar, or general) and the actions to be taken with the IOL (IOL exchange, reposition, and method of fixation).
The IOL power calculation requires accurate biometry. The previous IOL power, if available, is a useful starting point in the power calculations. The important questions are the choice of iris or scleral fixation of the IOL and the target refraction, he commented.
Dr. Ritterband is system director of refractive surgery, Mount Sinai Health System; assistant director, Cornea Service, New York Eye and Ear Infirmary of Mount Sinai, and professor of ophthalmology, Icahn School of Medicine at Mount Sinai, New York.
The incision can be created in the superior or temporal cornea and the size can range from 2.75 mm to 3.25 mm. The surgeon can restrict the incision to 2.75 mm if he or she is using an injector to insert the IOL
A larger incision, ranging in size from 3.0 mm to 3.25 mm, is the appropriate choice when the surgeon needs to remove or exchange an IOL. An incision as large as 6 mm to 7 mm is needed when removing a non-foldable polymethyl methacrylate (PMMA) lens, an anterior chamber IOL, or a plate haptic IOL. The location and angulation of the paracenteses depends on surgeon preference, the location of the main wound, and the type of fixation (iris vs sclera).
Endocapsular dislocation of a posterior chamber IOLs is the most frequent indication for intervention in these patients.
“In eyes with endocapsular dislocation of posterior chamber IOLs, a retinal consultant should remove all capsular bag remnants and move the dislocated IOL into the anterior chamber,” Dr. Ritterband explained. “The surgeon should make sure that a viscoelastic agent is present in the anterior chamber; the pars plana infusion pressure should be adjusted down to 10 mm Hg.
“It may be easier to remove the capsular remnants while holding the IOL in the posterior chamber,” he added. “It is ergonomically easier to bring the dislocated IOL fully into anterior chamber, using a vitrector to hold the IOL posteriorly and a Kuglen hook or a 25-gauge endoretinal forceps through the corneal paracentesis.”
In cases in which an anterior chamber IOL, a three-piece PMMA, or a plate haptic lens is removed, Dr. Ritterband advised that surgeons not cut the IOL in order to remove it and enlarge the wound to 6 mm to 7 mm.
In patients with a foldable, three-piece silicon or acrylic IOLs, Dr. Ritterband prefers to use an IOL scissors (MicroSurgical Technology) to cut the IOL. “It is helpful in this case if the wound is 3.25 mm or larger,” he added.
When removing a one-piece, acrylic IOL, Dr. Ritterband pointed out the IOL does not need to be cut and can be removed carefully from the eye through a 3.25-mm incision, using a toothed forceps.
When the surgeon opts for iris fixation of an IOL, Dr. Ritterband recommends using 9-0 or 10-0 Prolene suture with an Ethicon CTC 6L needle. For scleral fixation of the IOL, he uses a Gortex CV-8 needle or a 9-0 or 10-0 Prolene sutures with a Ethicon STC6 needle.
A relatively new technique, glue-assisted scleral fixation, involves the creation of scleral flaps and use of a biologic glue to secure the IOL in the posterior chamber. For this procedure, a crescent blade is used to create two partial-thickness scleral flaps at the 3 and 9 o'clock positions.
A 20- or 23-gauge MVR blade is used to make sclerostomies at 1.0 mm to 1.25 mm posterior to the limbus within the scleral flaps. The haptics are externalized using a 25-gauge, MaxGrip retinal forceps placed through the sclerostomy.
The haptics are then threaded into a scleral tunnel, created with a 25-gauge needle, perpendicular to the partial thickness sclera flap. The scleral flaps are glued down with the Tisseel (Baxter) adhesive to adhere the haptics in place and seal the scleral flaps.
The small corneal wound is closed with 10-0 nylon sutures and the conjunctiva overlying the scleral flaps can also be reapposed with the Tisseel adhesive.
Obtaining accurate biometry data using the IOLMaster (Carl Zeiss Meditec) or the Lenstar (Haag-Streit AG) is paramount. If accurate reading cannot be obtained, immersion A-scan biometry should be performed. Later day IOL power calculation formulas, i.e., the Haigis, Barrett, Holliday 2 formulas, should be used.
Dr. Ritterband targets in-the-bag placement. The target refraction should be discussed carefully with patients to establish realistic postoperative expectations.
In certain situations, the choice of fixation technique is dictated by other factors, according to Dr. Ritterband.
He pointed out that an anterior chamber IOL can be a poor choice in patients with pseudoexfoliation glaucoma or a disorganized anterior segment. The choice of an iris-sutured, posterior chamber IOL requires normal iris architecture and is best in patients over 75 years of age because of late-suture lysis or breakage.
An iris-sutured, posterior chamber IOL is contraindicated in eyes with poor iris anatomy, a younger patient, a history of recurrent hemorrhages, a previous diagnosis of uveitis-glaucoma-hyphema (UGH) syndrome, proliferative diabetic retinopathy, ectopia lentis, or previous dislocation with iris fixation, according to Dr. Ritterband.
The use of scleral flaps with glue are preferred in eyes with poor iris anatomy, younger patient, a history of recurrent hemorrhages, UGH syndrome, proliferative diabetic retinopathy, ectopia lentis, or previous dislocation with iris fixation.
These may be poor choices in patients with poor general health who cannot tolerate longer anesthesia times or have poor conjunctival tissue that may not allow for adequate coverage of the scleral flaps.
"With the emergence of glue-assisted haptic fixation with scleral flaps, there are fewer indications for scleral suturing of IOL's,” Dr. Ritterband said. “The use of a scleral-sutured IOL requires creation of bigger wounds because of the available IOL sizes, and clinical concerns include late suture hydrolysis with subsequent dislocation. Smaller scleral-based flaps and Hoffman pockets are technically challenging.”
The acrylic, three-piece IOLs that Dr. Ritterband prefers for iris fixation are the AcrySof MA60 anterior chamber IOL (Alcon Laboratories)–in powers ranging from 6 D to 30 D in 0.5-D increments; the AcrySof MA60MA (also from Alcon)–in powers ranging from -5.0 D to +5.0 S in 0.5-D increments; the Aaris EC-3 PAL IOL (Aaren Scientific)–powers ranging from 8 D to 30 D -30 in 0.5-D increments; and the Technis ZA9003 IOL (Abbott Medical Optics)–in powers ranging from 6 D to 30 D in 0.5-D increments.
Finally, when opting for scleral/glue-fixation, Dr. Rittenbrand prefers the Aaris EC-3 PAL IOL, which has haptics made of polyvinylidene fluoride. The haptics are sturdier but maintain the same flexibility as the PMMA haptics found on the MA60 lenses.
David Ritterband, MD
This article was adapted from a presentation Dr. Ritterband delivered at the Precision Ophthalmology 2016 Meeting. Dr. Ritterband has no financial interest in any aspect of this report.