JCRS January 2021
Photorefractive keratectomy has been a controversial procedure for treating keratoconus patients because the surgery removes tissue from an already thinning cornea. However, combining the latest PRK approach with epithelium-off cross-linking appears to offer a safe and an effective option to correct the spherocylindrical error and to minimise the level of aberrations in mild-to-moderate keratoconus, a new study suggests. A prospective case series included 19 patients (35 eyes) who all underwent topography/wavefront-guided (TWFG) PRK using the VISX STAR S4 IR excimer laser and the new iDesign 2.0 system, followed by accelerated epithelium-off CXL. All the assessed parameters showed statistically significant changes six months postoperatively. In particular, 80% of eyes achieved a postoperative UDVA of 20/25 or better, and 46% reaching 20/20. At the six-month follow-up mark, 57% were within ±0.50D and 86% had a postoperative spherical equivalent of ±1.00D. 71% achieved a six-month postoperative amount of cylinder within ±0.50D, vs only 14% preoperatively. The mean time for refractive and visual acuity stabilisation was 16.7 ± 3.9 weeks.
A Russo et al., “Topography/wavefront-guided photorefractive keratectomy combined with crosslinking for the treatment of keratoconus: preliminary results”, Vol. 47, #1, 11-17.
AI to optimise IOL inventory
An artificial intelligence study aimed at improving the discrepancy between target and actual IOL power in an African cataract campaign proved quite successful, a special report suggests. Researched utilised a machine learning model to evaluate patients from 29 cataract outreaches in Ethiopia between 2017 and 2018. This algorithm computes the optimal IOL supply distribution that would minimise the difference between actual implanted IOL power and targeted IOL power using a large set of biometry data. In the original data, only 45.6% of patients received their target IOL power and 23.6% received under-powered IOLs with current inventory with a 50% surplus. The AI-generated IOL inventory ensured that more than 99.5% of patients received their target IOL when using only 39% IOL surplus. The researchers believe that optimising the IOL inventory using this machine learning model might eliminate refractive error from insufficient inventory and reduce costs.
AR Brant et al., “Artificial intelligence in global ophthalmology: using machine learning to improve cataract surgery outcomes at Ethiopian outreaches”, Vol. 47, #1, 47(1):6-10.
Lower-energy SMILE, faster recovery
One of the main barriers to higher adoption rates of SMILE has been a slower visual recovery than LASIK postoperatively. A retrospective study of 147 eyes of 106 patients compared outcomes in FS-LASIK and low-energy SMILE. SMILE with lower energy settings (125-130nJ and 4. μm spot spacing) achieved postoperative day-one vision comparable with that of FS-LASIK. In addition, lower-energy SMILE caused less induced spherical aberration compared with that by FS-LASIK.
RD Hamilton et al. “Comparison of early visual outcomes after low-energy SMILE, high-energy SMILE, and LASIK for myopia and myopic astigmatism in the United States”, Vol. 47, #1,18-26.
