Eyeworld

EW REFRACTIVE 98 October 2018 by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer Presentation spotlight intracorneal ring segments (ICRS) could achieve good safety and effi- cacy. One retrospective study that evaluated ICL implantation after CXL in 30 progressive keratoconus eyes revealed that toric ICLs were an effective option for improving visual acuity for up to 2 years. 1 A second, unrelated investigation in which the Visian toric ICL (STAAR Surgical, Monrovia, California) was implanted for the treatment of residual refrac- tive error 6 months after ICRS and CXL in stable keratoconus showed good safety and efficacy in seven patients with moderate to severe keratoconus. 2 Despite the positive outcomes, Dr. Prakash noted the small sample sizes in these studies as a possible limiting factor. Who stands to benefit? The most critical factor for the insertion of toric phakic IOLs in keratoconus patients is the presence of stable, non-progressive ectasia. According to Dr. Prakash, in patients under 30 years of age, his protocol would be to perform CXL first and wait for at least 1 year to evaluate the patient's corneal topography before considering a toric phakic IOL. In patients who are older than 30 years of age, he requires docu- mented topographic corneal stabil- ity, usually three scans over at least 1 year, before he would consider a toric phakic IOL correction. Ectasia progression strongly influences the surgeon's choices. In an evaluation of current quantita- tive criteria for keratoconus progres- sion, Dr. Prakash maintained that it was important for change to be lower than the statistical limits and not progressive. His study includ- ed 100 eyes of 100 patients with tive laser procedures can jeopardize the already weak cornea in kerato- conus. Phakic IOL implantation is advantageous in such cases because it is a cornea sparing procedure. According to Dr. Prakash, phakic IOLs offer a large range of combina- tion options for keratoconic eyes, which often have both astigmatism and high myopia to contend with. Mostly it is the stability of cornea ectasia that is the surgeon's great- est concern, however, phakic IOL implantation is reversible and lens explanation is always an option if necessary. Previous studies on safety and efficacy revealed that toric pha- kic IOLs either in combination with corneal crosslinking (CXL) or Eye Care, NMC Specialty Hospital, Abu Dhabi, United Arab Emirates, is having the right refractive infor- mation to identify who the true beneficiaries are. "Only a subset of keratoconus patients will benefit truly from phakic IOLs, and it is very import- ant to choose the correct ones," Dr. Prakash said in a presentation he gave on the subject at the 2018 World Ophthalmology Congress. Where do toric phakic IOLs fit in? Refractive challenges abound in eyes with keratoconus, leaving it up to the eye surgeon to understand and weigh the risks and benefits. Abla- Specialist provides guidelines on the use of toric phakic IOLs in keratoconus patients T he implantation of toric phakic IOLs in eyes with keratoconus is complex. Ophthalmic surgeons have understandable concerns about potentially inducing higher order aberrations due to the compli- cated interplay of the phakic IOL's toricity and the corneal irregularity in these patients. The key to using toric artificial lenses, according to Gaurav Prakash, MD, FRCS, cornea and refractive surgery services, NMC Toric phakic IOLs in keratoconus Line diagram showing the effect of corneal shape in normal and keratoconic eye and corrective modalities; (a) normal cornea with a regular focus of rays from optical infinity; (b) keratoconic cornea (scattering and lack of clear focus of rays from optical infinity); (c) keratoconus with glasses (improved focus of some rays); (d) keratoconus with implanted collamer lens (almost similar optical effect as with glasses, however, reduced minification as the ICL is closer to nodal point than the spectacles); (e) keratoconus with specialized contact lenses (improved focus in more irregular cases of keratoconus as the contact lens/air interface now acts as the first refracting surface) OCT image with ICL in situ in a keratoconic eye Source (all): Gaurav Prakash, MD

• Cover