The Impact Of Ss-Ss Parameter, Measured By Ms-39 Device, For Determining Size Of Phakic Lens

The main purpose of this work is to verify whether the SS-SS (scleral spur - scleral spur) parameter, measured by the MS-39 device, can be used to determine the size of ICLs. In addition, the study aims to confirm the thesis that the determination of ICLs’ size based on the SS-SS parameter gives very good results in the desired position of the phakic ICL lens after implantation. Moreover, the assumption that the work seeks to support is the assertion that ICL’s size should be the closest to and/or be the first available value greater than SS-SS parameter value. 

Implanting phakic IOLs is a popular refractive surgery method, but knowledge about them remains limited despite over 2 million implanted lenses. A key challenge is achieving the desired post-surgical lens position (Vault), which depends on lens size. Existing calculators and size tables do not always predict the correct size, leading to improper PIOL placement. This study proposes a new method for calculating PIOL size, aiming to achieve consistent and predictable post-surgical positioning.

Study analyzed 161 eyes with implanted ICLs. Data included corneal diameter (WTW), SS-SS parameter, implanted lens size, and post-operative vault (optimal: 200-800µm). Based on vault, desired and undesirable sizes were identified. New size calculations based on vault and SS-SS were compared to implanted and desired sizes.

In 100% of cases, the desired ICL lens size (determined from the Vault parameter after lens implantation) is consistent with the size derived from the SS-SS parameter if the assumption is made that the this size is to be the first available larger than or closest to the value of the SS-SS parameter. In addition, in 80% of patients implanted with different lens sizes, using the size derived from the SS-SS parameter would yield the desired position in the anterior chamber.

Analysis shows the SS-SS parameter, alongside WTW and ACD, effectively determines ICL size for optimal placement. Choosing the size closest to or slightly larger than the SS-SS value is crucial for achieving the desired lens position. Notably, the SS-SS parameter is recommended when selecting ICL size for patients needing different sized lenses in each eye, maximizing success in achieving the desired position. ICLs’ size chosen in accordance with SS-SS parameter guarantees a greater chance of success when it comes to desired position of the phakic lens after implantation.