Review of current status of refractive lens exchange and role of dysfunctional lens index as its new indication

Abstract

Advances in phacodynamics and intraocular lenses (IOLs) has given second life to clear lens extraction (CLE) or refractive lens exchange (RLE) in recent years for the treatment of patients with high degrees of myopia, hyperopia, and astigmatism who are unsuitable for laser surgery. Furthermore, presbyopia treatment with RLE supplemented with multifocal or accommodating IOLs gives the dual benefit of correcting refractive errors with eliminating the need for cataract surgery. RLE should be consistent and effective for a good refractive outcome along with safety during the surgical procedure and in the postoperative period. Therefore, proper patient selection and accurate preoperative protocols for IOL power calculations and selection are important along with an appropriate choice of surgical procedure. Dysfunctional lens index is a new objective tool that helps surgeon to aid in diagnosing, counseling, and educating patients with dysfunctional clear lens. In this article, we give a brief overview about the application of RLE for individuals with presbyopia and refractive errors like myopia, hyperopia, and astigmatism who are not suitable for laser correction.

Keywords: Dysfunctional lens index; refractive lens exchange; spectacle independence.

Figure 1

This is a representative image of different grades of dysfunctional lens index (DLI), where (a) DLI <5 suggests severely impaired lens function, (b) DLI between 5-7 means moderate impairment and (c) DLI>7 is considered normal

Figure 2

Shows the correlation between (a) Strehl's ratio, (b) modulation transfer function area under the curve (MTF AUC) (c) Internal higher order aberrations (HOA) and (d) cataract grading. Figures on the right show (e) positive correlation of dysfunctional lens index (DLI) with MTF AUC, (f) Strehl's ratio (SR) and (g) negative correlation with internal HOA

Figure 3

Shows a case of 42-year-old gentleman with clear lens (a)and (b) who had come for refractive correction. Dysfunctional lens index showed severe impairment of lens function (c). Pentacam nucleus staging did not reveal any density changes (d)

Figure 4

A simplified algorithm to ease the decision-making process during refractive correction