Phakic intraocular lenses have become popular devices to correct nearsightedness (myopia). Although referred to as “contact lenses” these lenses are better described as phakic intraocular lens implants that supplement the natural lens of the eye. The increased popularity of phakic intraocular lenses has brought into focus the need for expert witness consultation when problems develop with this form of refractive technology.
Phakic intraocular lenses are considered by many ophthalmologists as an option for refractive correction of myopia. The Visian ICL manufactured by Starr Surgical and the Verisyse by Abbott Medical Optics are examples of phakic intraocular contact lenses.
In many patients a phakic intraocular lens implant may be viewed as not only an alternative, but the preferred option when corrected nearsightedness. When analyzing ICL implantation, a key question is the rationale for choosing this refractive technology over lasik or PRK. Patients who are predisposed to dryness may not be good candidates for laser refractive surgery. One of the key advantages of ICL compared with lasik is the lower incidence of dry eye symptoms after surgery. The presence of dry eyes may adversely affect calculations for intraocular lens powers when patients need cataract surgery.
Ophthalmologists also consider the risk/benefit ratio when considering ICL implantation. Since the ICL does not alter corneal curvature to a significant extent, patients have readings of corneal dimensions that are more accurate and reliable than having had a refractive procedure such as lasik or PRK. Unlike lasik, the risk for developing corneal deformities including ectasia is not present with phakic lens implantation. Patients with ICL implantation have a lower incidence of high order aberrations than lasik. Another key advantage of phakic lens implantation over lasik is that the lens is removable; the ICL may be removed postoperatively if the recipient of a phakic lens implant is unhappy with the results.
Expert analysis also considers standard of care issues when it comes to FDA approval and contraindication for ICL implantation. FDA approval for certain types of ICL is generally for patients with -3.00 dioptors to -20.00 dioptors of myopia. Patients who have corneas that are too thin, forme fruste keratoconus, or have inferior steepening of the cornea, who would otherwise be good candidates for lasik, are potential candidates for implantation of a phakic intraocular lens.
Many ophthalmologists recommend phakic intraocular lens implants for patients who have a refraction of -6.00 and above. A phakic intraocular lens implant may work particularly well in patients between in the -500 to -7.00 range. Patients with a refraction of -7.00 who would otherwise not be good candidates for lasik may be suitable candidates for a phakic lens implant. In many practices, phakic intraocular lens imploants are is preferable to PRK for patients with a correction of -3.00 and above because of relative comfort, speed of visual recovery, and superior quality of vision. In about 33% of cases, patients will have better vision than they had before surgery with contact lenses or glasses. Some investigators believe that night contrast sensitivity and night vision is better with phakic intraocular lens than with lasik. Pupil size does not seem to have a significant influence on vision with intraocular phakic lens implantation.
Suitable candidates for phakic intraocular lens implantation include patients between ages 21 and 45 years with an anterior chamber depth of greater than 3 mm and an anterior chamber angle of greater than III as determined by gonioscopic examination. A minimum endothelial density count is necessary. Patients with a significant degree of astigmatism may still be candidates for phakic lens implantation, although toric varieties of the phakic intraocular lens implant have not been approved for use in the United States.
Many ophthalmologists consider the most significant advantage of phakic intraocular lens implants over laser refractive procedures is that it does not make preoperative measurements and future lens calculations for cataract lens implant calculations for lens implantation more difficult.
Expert witness testimony for patients who have had phakic lens implantation to correct refractive issues considers indications, contraindications, surgical technique, and outcome when reviewing these cases. Patients who are ideal candidates may do very well with uncomplicated surgery. Patients who sustain complications or have long-term adverse affects may review their circumstances with an expert when deciding the best form of treatment for their individual circumstances.
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References:
1) Sanders, DR, Vukich, JA. Comparison of implantable contact lens and laser assisted in sito keratomileusis for moderate to high myopia. Journal of Cornea and External Disease. 2003:22(4):324-331
2)Kamiya, K, Igarashi, Shimizu, K., et al. Visual performance after posterior chamber phakic intraocular lens implantation and wavefront-guided in situ keratomileusis for low to moderate myopia. American Journal of Ophthalmology, 2012;1178-1186
3) Shin, JH, Ahn, H., Seo, KY, et al. Comparison of higher order aberrations after implantable collamer lens implantation and wavefront-guided LASEK in high myopia. Journal of Refractive Surgery. 2012:28(2):106-111
4) Vukich, JA. et al. Cataract and Refractive Surgery Today. May 2015. Supplement.