Eyeworld

keratoconus who underwent Sirius Scheimpflug topography (CSO, Flor- ence, Italy). 3 In the case studies that Dr. Prakash presented, he described his best outcomes with toric phakic IOLs in patients in their mid-30s whom he followed for at least 1 year, those with non-central kerato- conus, or in which ectasia was stable for 2 years, as opposed to those with progressive ectasia. "The corneal shape in keratoco- nus plays a role in refraction," Dr. Prakash explained. "The more irreg- ular the cornea, the poorer the best spectacle corrected distance visual acuity (BSCVA) and the more central the cone, the poorer the BSCVA as well. You can count on good results with toric phakic IOLs in kerato- conic eyes if the patient experiences good vision with glasses. Otherwise, the visual improvement primarily depends on the type and fit of spe- cialized contact lenses," he said. Contact lenses vs. phakic IOL and glasses Dr. Prakash explained that when using specialized contact lenses for keratoconus, the contact lens air interface becomes the anterior refracting surface. The comparative beneficial effect of contact lenses increases with increasing corneal irregularity in keratoconic eyes, smoothly rounding out the surface irregularities in simulation of a more normal corneal shape. Hard contact lenses can "ignore" the surface of the keratoconic cornea, which can be well visualized on OCT, he said. The effect of a lens placed inside the eye, however, has a different refractive effect that is more com- plicated to gauge. "When you have an implantable lens inside the eye, by contrast, it is like a myopic glass being shifted inside the eye near the focal point. You still have to consid- er the interface, therefore, typically patients who do well with glasses preoperatively are the ones who will do well with the implantable lens postoperatively," he said. Refractive correction with pha- kic IOLs should be limited to cases with good glasses-corrected refrac- tion, stable ectasia, and also to those who have repeatable and verifiable subjective refraction. Dr. Prakash personally prefers to have a perceiv- able, subjective improvement in ex- cess of BSCVA (with glasses) 20/40 or UDVA to BSCVA with at least three lines of improvement. "Preoperatively, do not try to treat the autorefraction. We are trying to treat the subjective refrac- tion in these patients," he said. "A repeatable subjective refraction is the best guide. Also, keep the target- ed postoperative refraction slightly myopic, as a hyperopic end result is usually poorly tolerated. Always inform the patient that reduced spectacle dependence is the target, not spectacle independence." The IOL implantation is fairly straightforward, the only variation being a slightly larger incision at the limbus, he explained. The alignment marks are crucial. "We use slit lamp based markings, as they mimic the position in refraction," he said. "Don't overfill the chamber with viscoelastic and therefore avoid too much irrigation post-implantation. Postoperatively, be aware that a good guide for visual outcomes is the 1-month and 3-month refrac- tion. Do not shy away from giving a temporary glasses correction if necessary. Redial only in cases of significant residual astigmatism; a small amount of astigmatism is not a problem. The stepwise planning for posterior chamber phakic IOL implantation in keratoconus needs patience and should include corneas that are stable and have subjective improvement with glasses. There should be no systemic or ocular con- traindications to posterior chamber phakic IOLs," he said. EW References 1. Antonios R, et al. Safety and visual outcome of Visian toric ICL implantation after cor- neal collagen crosslinking in keratoconus: up to 2 years of follow-up. J Ophthalmol. 2015:514834. 2. Dirani A, et al. Visian toric ICL implantation after intracorneal ring segments implantation and corneal collagen crosslinking in keratoco- nus. Eur J Ophthalmol. 2014;24:338–44. 3. Prakash G, et al. Evaluation of the robust- ness of current quantitative criteria for kerato- conus progression and corneal crosslinking. J Refract Surg. 2016;32:465–72. Editors' note: Dr. Prakash has no finan- cial interests related to his comments. Contact information Prakash: drgauravprakash@gmail.com 99 EW REFRACTIVE October 2018 ath ens 23 rd ESCRS Winter Meeting In conjunction with the 33 rd HSIOIRS International Congress 15 – 17 February 2019 Megaron Conference Centre, Athens, Greece www.escrs.org Abstract Submission Deadline: 31 October 2018

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