The Importance Of "Crystalline Lens Rise" In The Implantation Of Phakic Intraocular Lenses

Highlight the importance of measuring CLR (“Crystalline Lens Rise”) before determining the size of posterior chamber phakic intraocular lenses.

The measurement of CLR (“Crystalline Lens Rise”), or the anterior protrusion of the crystalline lens relative to the iris plane, has not been adequately considered to date in the implantation of posterior chamber phakic intraocular lenses when determining the appropriate lens size or diameter. The choice of lens size has been primarily based on the measurement of the corneal diameter, WTW (“White-to-White”), as an estimation of the sulcus diameter, which is where these lenses are supported.

An extreme clinical case for phakic intraocular lens implantation is presented. Despite high myopia, the anterior chamber was surprisingly shallow. The patient was unable to continue wearing contact lenses following an episode of severe superficial punctate keratitis due to limbal stem cell deficiency, which resolved only with autologous serum therapy. She refused to wear spectacles and was psychologically and socially affected. An interventional approach was therefore adopted. The refractive error was extreme: −17.5 −2.5 × 170° (right eye) and −17.5 −3.0 × 5° (left eye). We opted for the Eyecril Toric lens from Biotech Healthcare because it offered an estimated correction without residual refractive error, unlike the EVO+ Toric lens from Staar Surgical. According to the WTW values, the recommended lens diameter would have been 12.0 mm. However, the CLR was found to be markedly elevated, which led to selecting a larger 12.5 mm diameter in order to achieve adequate postoperative "vault" or distance between the lens and the crystalline lens. Even so, the postoperative vault was low. With a 12.0 mm diameter, lens–crystalline contact would likely have occurred. After more than one year of follow-up, no postoperative complications have been observed.

CLR (“Crystalline Lens Rise”) can be readily measured using OCT technology and should always be considered in the planning of phakic intraocular lens implantation.