JCRS HIGHLIGHTS

IOL calculation

Optimal calculation of intraocular lens (IOL) power in patients who have undergone myopic refractive surgery is an ongoing challenge. Problems include inaccurate measurement of the anterior corneal curvature by automated and manual keratometry or computerised videokeratography, inaccurate value of the keratometric index resulting from the modified relationship between the anterior and posterior corneal surface and incorrect estimation of the effective lens position resulting from these modifications. Korean researchers compare the results of IOL power calculation methods using different keratometry values after myopic refractive surgery. They calculated IOL power of 53 patients who had cataract surgery after refractive surgery using the SRK/T formula with true net power (TNP) and the equivalent K using the Pentacam Scheimpflug system. They calculated the simulated K, 2.0mm zone of total mean power (TMP 2.0mm) maps, and 4.0mm zone of total optical power (TOP 4.0mm) maps using the Orbscan II scanningslit topographer and keratometer of the IOLMaster partial coherence interferometer. They also calculated IOL power using the Haigis-L method with the corneal radius using the PCI system. The PCI axial length was used with all methods. The prediction error and absolute prediction error measured with the Haigis-L, TNP, TMP 2.0mm, and TOP 4.0mm were lower than the equivalent K, simulated K and PCI K. The percentages of correct refraction predictions within ±0.50 D, ±1.00 D and ±2.00 D in the Haigis-L method were the highest of all methods. The Haigis-L using corneal radius with the PCI measurement was the most predictable method for IOL calculation after corneal refractive laser surgery in patients without a clinical history.

• E Kim et al., JCRS, “Intraocular lens prediction accuracy after corneal refractive surgery using K values from 3 devices”, Volume 39, No. 11, 1640-1646.

Beginning surgeons

ECCE or phaco, which technique should residents learn first? Some argue that ECCE be given before phacoemulsification experience to establish the fundamental skills of ophthalmic surgery. Others argue that ECCE is best taught to more experienced residents and used only when necessary to optimise patients' visual outcomes and recovery. US researchers compared data collected for cases performed over a sixyear period during which initially the first primary surgeon cases were ECCE and later, the first primary surgeon cases were phacoemulsification. Complications occurred in six of 244 cases in which phacoemulsification was performed by a beginner resident primary surgeon and in seven of 172 cases in which ECCE was used (P=.40). Posterior chamber IOLs were placed in all but two phacoemulsification cases and four ECCE cases (P=.24). Three cases in the phacoemulsification group and one case in the ECCE group required a reoperation within 90 days (P=.65). The researchers conclude that phacoemulsification cataract extraction can be taught effectively to residents with no cataract surgery experience as a primary surgeon.

•  LA Meeks et al., JCRS, “Outcomes of manual extra capsular versus phacoemulsification cataract extraction by beginner resident surgeons”, Landen et al Volume 39, No. 11, 1698 -1701

Wet lab vs. simulator

Investigators compared the operating room performance of ophthalmology residents trained by traditional wet-lab versus surgical simulation on the continuous curvilinear capsulorhexis portion of cataract surgery. The prospective randomised study compared 10 residents trained in the wet lab and 11 on the simulator. There was no significant difference in overall scores of initial surgery performance between the two groups. There was no significant difference in any individual score except time, with the wet-lab group being slightly faster than simulator group (P=.038). The time to pass the simulator curriculum was predictive of the time and overall performance in the OR.

 • MK Daly et al., JCRS, “Efficacy of surgical simulator training versus traditional wet-lab training on operating room performance of ophthalmology residents during capsulorhexis in cataract surgery”, Volume 39, No. 11, 1734-1741.