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JCRS highlights selected by Professor Thomas Kohnen

Vol: 44 Issue: 11

Thomas Kohnen

Posted: Friday, December 7, 2018


JCRS November 2018

POWER PREDICTION IN SHORT EYES
IOL power prediction in eyes with short axial lengths continues to be a challenge. Indian researchers conducted a retrospective study in 50 eyes of 50 patients with axial lengths less than 22mm, comparing six IOL power formulas: the Barrett Universal II, Haigis, Hoffer Q, Holladay 2, RBF Method and SRK/T. To eliminate bias, the study used partial coherence interferometry, implanted the same IOL type and had the same surgeon perform all the surgeries and same refractionist conduct all the biometric analyses. The team applied the Friedman test to compare the median absolute error between the six formulas after the zeroing of the mean numerical error. The formulas were equally accurate in predicting the IOL power in the study eyes. They conclude that larger studies will be needed to determine the formula of choice in patients with short axial lengths. AK Shrivastava et al., JCRS, “Precision of intraocular lens power prediction in eyes shorter than 22 mm: An analysis of 6 formulas”, Vol. 44, Issue 11, 1317-1320.
EPI-ON CORNEAL CROSS-LINKING
A new corneal cross-linking technique could help eliminate the potential complications associated with conventional epi-off surgery, a new study suggests. Some 512 eyes of 308 patients with keratoconus or forme fruste keratoconus, and 80 eyes of 55 patients with ectasia after LASIK, were treated with a new riboflavin formulation without epithelial removal, then exposed to UV light (365nm) at 4mW/cm2 with on-off cycling for 30 minutes. The riboflavin formulation did not contain dextran. It was optimised at a specific concentration, pH and osmolarity to enhance absorption and it contained sodium iodide, which acted as an excipient. Uncorrected and corrected distance visual acuities improved by 1 to 1.5 Snellen lines at one and two years postoperatively (P<0.0001). Mean Kmax decreased by 0.48D at two years. R Doyle Stulting et al., JCRS, “Corneal crosslinking without epithelial removal”, Vol. 44, Issue 11, 1363-1370.
SMILE RETREATMENT OPTIONS
Small-incision lenticule extraction (SMILE®) retreatment is performed when the refraction is overcorrected or undercorrected or optical regression has occurred. Because it is a relatively new surgery, data on the retreatment rates are limited. Options include surface ablation, thin-flap LASIK, secondary SMILE and cap-to-flap procedures. To help surgeons choose the option tailored to their specific patient needs, Moshirfar and colleagues constructed a chart of the major advantages and disadvantages of each retreatment option and the available visual outcomes. They also designed a simple algorithm that might provide additional help in selecting the appropriate retreatment, each of which are described in detail. M Moshirfar et al., JCRS “Surgical options for retreatment after small-incision lenticule extraction: Advantages and disadvantages”, Issue 11, 1384-1389.