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.