<p>Both Subjective Emotional Distress and Visual Handicap Correlate with Belin ABCD Classification in the Worse Eye as Measured with the “Keratoconus End-Points Assessment Questionnaire” (KEPAQ)</p>

Abstract

Background: Keratoconus is a disease characterized by progressive corneal distortion and quality of vision. So far, no study using disease-specific scales has evaluated whether different stages of the disease correlate with higher quality of life (QoL) compromise. Methods: A total of 114 patients with a confirmed diagnosis of Keratoconus were included in this retrospective study. All patients underwent a clinical and a Pentacam evaluation. They were also administered the "Keratoconus End-Points Assessment Questionnaire" (KEPAQ). Belin ABCD criteria were used for Keratoconus classification. "Better eye" was defined as the eye with the lowest maximum keratometry value. Spearman Rank Order Correlation was used to determine the correlation between the different Belin criteria and the KEPAQ scores in both subscales. Results: Mean age was 28.13 ± 11.57 years, with 39.47% of patients being male. Mean score for the KEPAQ-E was 2.33 ± 3.40 Logit, while for the KEPAQ-F, it was 1.85 ± 3.61 Logit. Criteria A (anterior elevation), B (posterior elevation) and D (visual acuity) in the worse eye correlated significantly with a greater decrease in QoL (p < 0.05 for all correlations). No correlation could be found regarding the better eye. Conclusion: A greater corneal distortion in the worse eye, as determined by Belin ABCD, is associated with a greater decrease in patient's QoL. Surgical improvement of the worse eye should probably be performed before surgery of the better eye, as it may provide a better response regarding the quality of life improvement.

Standardizing the measurement and classification of quality of life using the Keratoconus End-Points Assessment Questionnaire (KEPAQ): the ABCDEF keratoconus classification

“…Measuring quality of life “is particularly important in keratoconus because it has an early onset, is progressive and chronic in nature and can cause serious vision impairment” [ 16 ]. Although some relationship has been demonstrated between corneal distortion and emotional distress [ 3 ], it is clear that “the impact of keratoconus on quality of life may be disproportionate to the clinical measures such as best-corrected visual acuity” [ 16 ]. Therefore, specifically measuring and classifying quality of life in keratoconus is of top priority if the researchers or clinicians want to have a more complete and holistic picture of the effect the disease has on the patient.…”

“…The problem of using such non-specific scales in different populations from what they were initially designed for, is that results are not necessarily reliable or trustable. So far only two instruments have been specifically created and validated in keratoconus subjects: the KORQ [ 2 , 17 – 19 ] and the KEPAQ [ 1 , 3 , 6 ]. Although both scales measure subjective functional compromise by the disease, the main difference between them is the fact that the KEPAQ also has a sub-scale for measuring emotional distress secondary to keratoconus [ 1 ].…”

“…All patients are also given the choice to select “Not applicable” if they feel the question does not correlate with any situation in their daily lives. Early tables for converting the total sum score into a non-transformed Rasch-derived score were previously published by our group [ 1 , 6 ], with a greater KEPAQ score meaning less disability by disease [ 3 ]. A complete description and explanation on the origin and philosophy behind the development of the KEPAQ is available here [ 1 ].…”

“…A complete description and explanation on the origin and philosophy behind the development of the KEPAQ is available here [ 1 ]. Our group has previously demonstrated the KEPAQ to comply adequately to the Rasch model [ 1 ], to be unidimensional and reliable [ 6 ] and to correlate well with the Belin ABCD classification [ 3 ].…”

“…Although we have demonstrated that the KEPAQ complies with the stringent expectations of the Rasch model [ 1 ], and correlates well with corneal distortion [ 3 ], there is still some uncertainty regarding the best way to calculate, report and interpret results from the scale, especially for non-Rasch experienced researchers. Prior published papers have suggested calculating KEPAQ score by a raw-score-to-Rasch-measure table [ 1 ], but it is clear that this is not optimal as it does not allow for calculation when there are missing items.…”