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PURPOSE: To review the intraoperative and postoperative complications after intracorneal ring segment implantation and to report the explantation rate among the available scientific literature. METHODS: Three different databases (PubMed, Web of Science, and Scopus) were assessed from January 1995 to June 2019. The keywords used were: ring, rings, ICRS (intracorneal ring segments), segment, segments or Intacs, complication, explantation, explanted, retired, and removal. RESULTS: The selection process of this systematic review study is described in a flow diagram. A total of 39 studies published between 1995 and 2019 were included. Sixteen studies were case reports, 21 were case series studies, and 2 were chart analysis works. This study enrolled 1,946 participants, and 2,590 eyes were included. The postoperative complications described in most studies included migration, ring extrusion, corneal thinning, corneal melting, and some type of infective keratitis. These complications together with glare, halos, fluctuating vision, neovascularization, foreign body sensation, or pain represented most of the causes. The percentage rate of explantation ranged from 0.5% up to 83.3%. If we analyze those articles with a high number of implantations (2,124 eyes), an explantation rate between 0% and 1.4% was obtained. CONCLUSIONS: The complication rate and explantation ratio in segments of the intracorneal ring segments analyzed in the available scientific literature are minimal. Therefore, patient selection, surgery planning, and postoperative follow-up are critical to the success of surgery. [ J Refract Surg . 2019;35(11):740–747.]

posterior chamber phakic intraocular lens (pioL) implantation is a common option for correcting moderate-to-high ocular refractive defects. Because this pIOL is implanted on ciliary sulcus, the distance between the back surface of the pIOL and the anterior surface of the crystalline lens, that it is known as vault, should be measured in different conditions to ensure the technique's safety. Cyclopentolate is a drug that dilates the pupil and relaxes accommodation (cycloplegia). It is often used for different ocular examinations and for other medical purposes. However, there is no evidence of the effect of this drug on vault. This study quantified central vault changes associated with cyclopentolate instillation. We measured the vault under normal conditions (pre-cycloplegic instillation) and after instilling cyclopentolate on 39 eyes of 39 patients with implanted pIOL. Our results suggest that cyclopentolate instillation may induce changes to vault in eyes with implanted pIOL. These changes seem safe and are mainly associated with vault under normal conditions, but also with anterior chamber depth, pupillary diameter and pIOL size. Visian Implantable Collamer Lens (ICL, STAAR Surgical) is a foldable posterior chamber phakic intraocular lens (pIOL) designed to correct moderate-to-high myopia 1. The latest models have a central hole that allows better aqueous humour exchange between the anterior and posterior chambers without the need for iridotomy 2. These models present safe and efficacious results as previous models with no hole 3,4. The central vault is defined as the distance between the back surface of the ICL and the anterior surface of the crystalline lens. An appropriate vault has been suggested to be between 250 and 750 µm 5. An insufficient vault may induce anterior subcapsular cataract due to the contact between the ICL and the anterior lens capsule 1,6,7. Excessive vaulting can cause angle closure, pupillary blockage or pigmentary dispersion syndrome, which can increase intraocular pressure and, thus, the risk of glaucoma 8-11. Therefore, it is important to measure this distance to ensure the technique's safety. Changes in anterior segment structures appear during accommodation, such as reduced anterior chamber depth (ACD), inducing proximity between the anterior surface of the crystalline lens and the cornea with appearance of synkinetic myosis 12. The ICL is implanted in the ciliary sulcus. Given its location, dynamic interactions take place between the pIOL and the surrounding structures. Some authors have studied these effects on the vault by accommodative stimulus 13-17 , instillation of pilocarpine for pharmacologically-induced accommodation 13,18 , light-induced pupil constriction 15,17,19 and mydriasis. 20 However, no studies have quantified the cycloplegic effect on the central vault. Cyclopentolate is a drug that dilates the pupil and relaxes accommodation. Preoperative and postoperative evaluations of post-cyclopentolate instillation (by cycloplegic eyedrops) are necessary with patients who ...

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