Changing Trends in Keratoconus Management

Comparative analysis of the visual performance after implantation of the toric implantable collamer lens in stable keratoconus: a 4-year follow-up after sequential procedure (CXL+TICL implantation)

Aims

To report on 4-year postoperative visual performance with the toric implantable collamer lens (TICL) for stable keratoconus after sequential procedure (corneal collagen crosslinking plus TICL implantation).

Methods

Forty eyes of 24 patients with stable keratoconus with myopia between 0.00 and −18.00 dioptres (D) and astigmatism between 1.25 and 8.00 D were evaluated in this prospective interventional study (https://clinicaltrials.gov/ct2/show/NCT02833649). We evaluated refraction, visual outcomes, astigmatic changes analysed by Alpins vector, contrast sensitivity, aberrometry, modulation transfer functions (MTFs), defocus curve, and operative and postoperative complications.

Results

At 4-year follow-up, 45% had 20/20 vision or better and 100% had 20/40 or better uncorrected visual acuity (UCVA). Vector analysis of refractive astigmatism shows that the surgically induced astigmatism (SIA) (3.20±1.46 D) was not significantly different from the target induced astigmatism (TIA) (3.14±1.42 D) (p=0.620). At 4 years postoperatively, none of the eyes showed a decrease in UCVA, in contrast to 24 eyes in which UCVA was increased by ≥1 lines, with contrast sensitivity and improvement in total aberrations and MTF value at 5 per degree (*p=0.004) after TICL implantation. The cumulative 4-year corneal endothelial cell loss was ≤5%. No patients reported dissatisfaction. At the end of follow-up, the vault was 658±54.33m (range, 500–711) and the intraocular pressure was 11.7±2.08 mm Hg. Occurrences of glare and night-driving troubles diminished after TICL surgery.

Conclusion

The results from this standardised clinical investigation support TICL implantation from clinical and optical viewpoints in patients with stable keratoconus.

Trial registration number

NCT02833649, Pre-results

Analysis of the VSX1 gene in sporadic keratoconus patients from China

Background

Keratoconus normally presents as a sporadic disease. Although different studies have found sequence variants of the visual system homeobox 1 (VSX1) gene associated with keratoconus in humans, no research has detected such variants in sporadic keratoconus patients from China. To investigate the possibility of VSX1 being a candidate susceptibility gene for Chinese patients with sporadic keratoconus, we performed sequence screening of this gene in such patients.

Methods

Whole DNA was obtained from the leukocytes in the peripheral venous blood of 50 patients with sporadic keratoconus and 50 control subjects without this ocular disorder. Polymerase chain reaction single-strand conformation polymorphism analysis and direct DNA sequencing technology were used to detect sequence variation in the five exons and splicing regions of the introns of the VSX1 gene. The sequencing results were analyzed using DNAstar software.

Results

One novel missense heterozygous sequence variant (p.Arg131Pro) was found in the first exon of the VSX1 gene in one keratoconus patient. Another heterozygous sequence variant (p.Gly160Val) in the second exon was found in two keratoconus patients. These variants were not detected in the control subjects. In the third intron of the VSX1 gene, c.8326G > A nucleotide substitution (including heterozygous and homozygous change) was also discovered. The frequency of this variation did not differ significantly between patients and controls, it should belong to single-nucleotide polymorphism of the VSX1 gene. Bioinformatic analysis also predicted that one missense sequence variation (p.Arg131Pro) may not cause a pathogenic change.

Conclusions

In this study, we added one novel missense sequence variation (p.Arg131Pro) in the coding region of the VSX1 gene to the range of VSX1 coding region variations observed in patients with sporadic keratoconus from China. Our work suggests that VSX1 sequence variants might be involved in the pathogenesis of sporadic keratoconus, but their precise role in disease causation requires further investigation.