Analysis of the correlation between ophthalmic examination and quality of life outcomes following intracorneal ring segment implantation for keratoconus.

PURPOSE: To analyze the correlation between quantitative measurements outcomes and keratoconus patients' vision related quality of life (v-QoL) following intrastromal corneal ring segment implantation.

METHODS

The NEI-RQL (National Eye Institute Refractive Error Quality of Life) was administered to patients requiring intrastromal corneal ring segment implantation, before and after surgery, wearing best correction for 40 days minimum. Visual acuity, refraction, corneal topography, aberrometry data (VOL-CT. software) and contrast sensitivity were recorded before and 3 months after surgery. The main outcome measures were best corrected visual acuity, refraction, steep keratometric value (Kmax), aberrometry, contrast sensitivity and v-QoL.

RESULTS

There were 42 keratoconic patients (69 eyes): 19 male and 23 female, mean age 24.9 ± 5 years in this prospective study. Binocular best corrected visual acuity improved (0.13 ± 0.03 before to -0.01 ± 0.01 logMAR after surgery, p<0.001). There was a statistically significant improvement in mean spherical refraction (2.81 ± 0.44 to 1.71 ± 0.31), cylinder component (3.89 ± 0.22 to 1.82 ± 0.21), spherical equivalent (4.55 ± 0.46 to 2.40 ± 0.30), Kmax (55.92 D ± 0.62 to 52.16 D ± 0.58 D) and root mean square low order (p<0.001). Contrast sensitivity (CS) improved at all spatial frequencies: at 6 cpd improvement was higher. Root mean square higher order did not improved p=0.422. There was significant improvement across all NEI-RQL scales after surgery. Multivariate analysis showed that gender (males more satisfied than females), cylinder (1 D reduction improves 5 points in general NEI-RQL scores) and normal contrast sensitivity at 3 and 6 cpd were correlated with v-QoL. Other variables such as best corrected visual acuity, root mean square low order, root mean square higher order and Kmax did not show influence on NEI-RQL scores.

CONCLUSIONS

The best patient response predictors with the NEI-RQL instrument were gender, normal CS at 3 and 6 cpd and cylinder reduction. The use of this questionnaire was crucial to assess the influence of optical tests on v-QoL in keratoconus patients who were referred for intrastromal corneal ring segment implantation.