Comparison of results obtained with keratophakia, hypermetropic keratomileusis, intraocular lens implantation, and extended-wear contact lenses.
The limited experience with LRK precludes a valid comparison with IOLs and extended-wear contact lenses. Only observations, unsupported by valid statistical analysis, are possible. Some of these observations follow. Technically, LRK is very difficult. In their present form, the classic Barraquer procedures could never be used widely. However, if lenticle banks were to supply preground lenticles, the level of difficulty of LRK procedures would be comparable to IOL implantation. The magnitude of refractive correction possible with LRK compares favorably with that of contact lenses and IOLs. However, the accuracy of achieving a given correction is lower with LRK. Unlike contact lenses or IOLs, LRK induces both regular and irregular astigmatism. The latter accounts, in part, for the delayed visual result with LRK. The percentage of patients with 20/40 or better vision following LRK compares favorably with the percentages for contact lenses or IOLs, whereas the percentage of patients with 20/25 or better vision does not. This is true for at least 1 year following surgery. Compared to extended-wear contact lenses, IOLs and LRK typically require less commitment, fewer postoperative visits, and less expenditure by the patient, in terms of time and money, to achieve full-time correction. Although LRK is associated with a number of postoperative complications, none are known to be intraocular, and there have been no known reports of permanent severe visual loss. In contrast, the patient with an extended-wear contact lens or IOL is permanently at risk to develop sight-threatening complications. This is not the case with LRK, which has no known complications after the early postoperative period. Application of the IOL or extended-wear contact lens to the neonate or pediatric patient is associated with increased risk and difficulty. This may not be true with LRK, especially epikeratophakia. The major advantages of LRK appear to be permanent optical correction without the threat of intraocular or long-term complications and the ability to correct contact lens failures without the necessity of reentering the eye. Its major disadvantage is a slightly reduced visual acuity with delayed visual result. Extended-wear contact lenses, IOLs, and LRK are each unique enough that they should be adjuncts to one another. These corrective modalities should be applied judiciously by the patient-surgeon team to the best advantage of the given patient.
D001036:Aphakia, Postcataract / Q000601:surgery; D003262:Contact Lenses, Extended-Wear / Q000009:adverse effects; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects; D003315:Cornea / Q000601:surgery; D016039:Corneal Transplantation; D005069:Evaluation Studies as Topic; D006801:Humans; D006956:Hyperopia / Q000601:surgery*; D007431:Intraoperative Complications / Q000453:epidemiology; D007910:Lenses, Intraocular / Q000009:adverse effects; D011183:Postoperative Complications / Q000453:epidemiology; D012092:Replantation / Q000379:methods*; D014792:Visual Acuity