EyeWorld Asia-Pacific September 2019 Issue

EWAP SEPTEMBER 2019 55 REFRACTIVE ADVERTISER LISTING U ntil recently, the popular IOL power calculation formulas were generally based on thin lens vergence formulas. These are simple mathematical formulas that are easy to execute. A simple old-fashioned calculator can easily compute the calculations. It worked well and had served us well. With the increasing accuracy of measuring devices and the enormous scalability of computational power, more can be done. Complex calculations such as multi-thread parallel calculations and expansive iterations are now a «œÃÈLˆˆÌÞ° /œ}i̅iÀ ܈̅Lˆ} œÀ “i}> `>Ì>] >À̈wVˆ> ˆ˜Ìiˆ}i˜Vi ˆÃ ˜œÜ > Ài>ˆÌÞ° 7ˆÌ…Ì…iÃi `iÛiœ«“i˜Ìà and the demand for better refractive outcomes, IOL power calculation is undergoing a revolution. We have been seeing many new and innovative methods of formulating IOL power in the last few years. /…i }i˜iÀ>̈œ˜> V>ÃÈwV>̈œ˜ œv " «œÜiÀ V>VՏ>̈œ˜ vœÀ“Տ> ˆÃ Vœ˜vÕȘ}° Ì ˆÃ…ˆÃ̜ÀˆV> >˜` V>˜ Li misleading. As explained in Koch and Weikert’s article, later generations of formulas are perceived to be better but that may not be the case. …>Ûi >««Àœ>V…i` >˜` V>ÃÈwi` ̅iÃi vœÀ“Տ>à ˆ˜Ìœ ̅Àii LÀœ>` }ÀœÕ«Ã\ `>Ì>‡`ÀˆÛi˜] œ«ÌˆV>] >˜` > Vœ“Lˆ˜>̈œ˜ œv LœÌ…° /…i V>ÃÈwV>̈œ˜ ˆÃ L>Ãi` œ˜ ̅i Vœ˜Vi«Ì œv ̅i vœÀ“Տ>° /…i `>Ì>‡`ÀˆÛi˜ }ÀœÕ« ˆÃ ÃÕL‡`ˆÛˆ`i` ˆ˜Ìœ Ìܜ }ÀœÕ«Ã\ Ài}ÀiÃȜ˜ >˜` >À̈wVˆ> ˆ˜Ìiˆ}i˜Vi° /…i œ«ÌˆV> }ÀœÕ« ˆÃ vÕÀ̅iÀ ÃÕL‡`ˆÛˆ`i` into three groups: simple thin lens vergence, complex thick lens vergence, and ray tracing. The hybrid group stands alone. All together there are six groups (Table 1). Data-Driven Optical Approach Hybrid Regression ƂÀ̈wVˆ> Intelligence Simple Thin Lens Vergence Complex Thick Lens Vergence Ray Tracing Combination SRK SRK II Clarke Hill-RBF Binkhorst Colenbrander Holladay 1 Holladay 2 Hoffer Q Hoffer H5 Haigis SRK-T Barrett EVO Olsen- PhacoOptics Okulix FullMonte IOL Kane Ladas Super Formula 6CDNG %NCUUKƂECVKQP QH +1. HQTOWNCU KPVQ VJTGG DTQCF ITQWRU Source: Fam Han Bor, MD /…i >LœÛi ˆÃÌ ˆÃ ˜œÌ i݅>ÕÃ̈Ûi° /…i >LœÛi V>ÃÈwV>̈œ˜ ˆÃ ȓˆ>À ̜ ̅>Ì «Àœ«œÃi` LÞ œV…>˜` 7iˆŽiÀÌ° /…ˆÃ vœÀ“Տ>ˆV V>ÃÈwV>̈œ˜ }ˆÛià > LiÌÌiÀ ՘`iÀÃÌ>˜`ˆ˜} œv ̅i “iV…>˜ˆÃ“à œv ̅i vœÀ“Տ>Ã] ̅iˆÀ ÃÌÀi˜}̅à and limitations. It is more helpful in clarifying decision making and choosing the appropriate formula to use in the relevant circumstances. The regression method is essentially obsolete and should be avoided. The simple thin lens vergence method is still relevant for its simplicity; it is easy to start a new IOL with. The newer formulas are improving our predicted outcomes in an expanding range of eyes. >}Àii ܈̅œV…>˜` 7iˆŽiÀÌ° Ƃ ˜iÜ v՘V̈œ˜> V>ÃÈwV>̈œ˜ ˆÃ ˜iViÃÃ>ÀÞ] ̈“iÞ] >˜` “œÀi ˆ˜ÌՈ̈Ûi° 'FKVQTUo PQVG &T (CO FGENCTGF PQ TGNGXCPV ƂPCPEKCN KPVGTGUVU Fam Han Bor, MD Senior Consultant and Head, Cataract & Anterior Segment, NHG Eye Institute, Tan Tock Seng Hospital 11 Jalan Tan Tock Seng dr.fam.eye@gmail.com ASIA-PACIFIC PERSPECTIVES Alcon Page 2, 40-51 www.alcon.com Appasamy Associates Page 15 www.appasamy.com Feather Safety Page 18 www.feather.co.jp Haag Streit Page 37 www.haag-streit.com Johnson & Johnson Vision Page 5, 80 www.jjvision.com Oculus Page 35 corneal-biomechanics.com VSY Biotechnology Page 12 www.vsybiotechnology.com Zeiss Page 28-31 www.zeiss.com ASCRS Page 56 www.ascrs.org APACRS Page 7,8, 21 www.apacrs.org