An installed<unk> , with flash photography An installed<unk> , without flash photography LASIK can correct myopia up to -12 to -14 D. The higher the intended correction the thinner and flatter the cornea will be post-operatively. For LASIK surgery, one has to preserve a safe residual stromal bed of at least 250 µm, preferably 300 µm. Beyond these limits there is an increased risk of developing corneal ectasia (i.e. corneal forward bulging) due to thin residual stromal bed which results in loss of visual quality. Due to the risk of higher order aberrations there is a current trend toward reducing the upper limits of LASIK and PRK to around -8 to -10 D.<unk> es are safer than excimer laser surgery for those with significant myopia.<unk> es are contraindicated in patients who do not have a stable refraction for at least 6 months or are 21 years of age or younger. Preexisting eye disorders such as uveitis are another contraindication. Although<unk> s for hyperopia are being investigated, there is less enthusiasm for these<unk> es because the anterior chamber tends to be shallower than in myopic patients. A hyperopic model ICL (posterior chamber<unk>  is available. Corneal endothelial cell count less than 2000-2500 cells/mm² is a relative contraindication for<unk>  implantation. Advantages<unk> s have the advantage of treating a much larger range of myopic and hyperopic refractive errors than can be safely and effectively treated with corneal refractive surgery. The skills required for insertion are, with a few exceptions, similar to those used in cataract surgery. The equipment is significantly less expensive than an excimer laser and is similar to that used for cataract surgery. In addition, the<unk>  is removable; therefore, the refractive effect should theoretically be reversible. However, any intervening damage caused by the<unk>  would most likely be permanent. When compared with clear<unk>  extraction, or refractive<unk>  exchange the<unk>  has the advantage of preserving natural accommodation and may have a lower risk of postoperative retinal detachment because of the preservation of the crystalline<unk>  and minimal vitreous destabilization. Disadvantages<unk>  insertion is an<unk>  procedure. With all surgeries there are associated risks. In addition, each<unk>  style has its own set of associated risks. In the case of<unk> s made of polymethylmethacrylate (PMMA), surgical insertion requires a larger incision, which may result in postoperative astigmatism. By comparison,<unk> S made of collamer (a foldable gel-like substance) requires a very small incision due to the flexibility of the material and thus significantly reduces astigmatism risk. In the cases where refractive outcomes are not optimal, LASIK can be used for fine-tuning. If a patient eventually develops a visually significant cataract, the<unk>  will have to be explanted at the time of cataract surgery, possibly through a larger-than-usual incision. Another concern is progressive shallowing of the anterior chamber which normally occurs with advancing age due to the growth of the eye's natural<unk> . Multiple studies have shown a 12-17 µm/year decrease in the anterior chamber depth with aging. If a<unk>  IOL patient is assumed to have a 50-year lifespan, the overall decline in ACD may add up to 0.6-0.85 mm, long-term data about this effect are not available. This concern is more important in ICL because it is implanted in the narrowest part of the anterior segment.
Phakic intraocular lens
Persistent hyperplastic primary vitreous
Rigid gas permeable lens
Angle-supported intraocular lens
Blast-related ocular trauma
Recurrent corneal erosion
Retinal implant
Intraoperative floppy iris syndrome