Corneal topometric indices and proclivity toward corneal ectasia in vernal keratoconjunctivitis

PURPOSE

To investigate changes in topometric corneal indices and proclivity toward corneal ectasia, as well as keratometric indices and anterior chamber dimensions in palpebral vernal keratoconjunctivitis (VKC).

METHODS

This study included 80 patients with clinically established symptoms of grade 0 or grade 1 palpebral VKC (group 1) and 66 healthy participants (group 2). After a comprehensive ophthalmic examination including best-corrected visual acuity, intraocular pressure measurements and slit-lamp biomicroscopy, pachymetric indices and anterior chamber dimensions were measured using the Pentacam HR rotating Scheimpflug device. Topometric indices, which are particularly useful for determining proclivity toward corneal ectasia, were extracted from a topometric map.

RESULTS

In groups 1 and 2, the mean ages were 13.11±5.22 and 16.45±5.09 years, respectively. The mean age at disease onset in group 1 was 10.09±5.03 years, and the mean disease duration was 36.23±8.43 months. Group 1 had significantly higher mean topometric indices than group 2, particularly the index of surface variance (P=0.001), index of vertical asymmetry (P=0.007), center keratoconus index (P=0.050), and Belin/Ambrosio enhanced ectasia total deviation value (P=0.032). Mean posterior corneal astigmatism differed significantly between groups 1 and 2 (P=0.003).

CONCLUSIONS

Significantly higher mean topometric indices in VKC indicate a proclivity for corneal ectasia, which could be attributed to general changes in the corneal ultrastructure caused by persistent itching-induced eye rubbing.

Comparison of obstructive sleep apnea syndrome and keratoconus patients on elevation maps

PURPOSE

This study aimed to compare the tomographic features of the cornea on elevation maps between obstructive sleep apnea syndrome (OSAS) and keratoconus (KC) patients and to investigate the presence of susceptibility to ectatic corneal diseases in OSAS patients.

DESIGN

This is a comparative cross-sectional case-control study.

METHODS

This study included 84 eyes of 42 patients diagnosed with severe OSAS using polysomnography (apnea/hypopnea index > 30), 84 eyes of 56 patients diagnosed with keratoconus, and 84 eyes of 42 healthy subjects as control group and evaluated in three groups. Elevation maps of all the groups were performed using Pentacam, and topometric, pachymetric, and deviation indices were recorded.

RESULTS

The study included 252 eyes of 130 participants divided in three groups. Comparing all the tomographic keratometric values, a significant difference was found among the three groups. All keratometric values were found to be higher in the OSAS patients group compared to those in the control group. Also topometric indices and Belin-Ambrosio enhanced ectasia display (BAD) were observed to be higher as in subclinical keratoconus and statistically significant when compared to those in the control group.

CONCLUSION

The study reveals the tomographic corneal characteristics and topometric and pachymetric indices of patients with severe OSAS at the time of diagnosis; these findings statistically significantly differ from the control group. In addition to the known association of floppy eyelid in OSAS patients, the suspicion of keratoconus should be kept in mind.

Longitudinal corneal tomographical changes in eyes of patients with unilateral and bilateral non-progressive keratoconus

AIM

To evaluate the tomographic indices changes in keratoconic eyes which were classified as unilateral and bilateral non-progressive keratoconus according to the definition of Global Consensus on keratoconus and ectatic disease.

METHODS

Fifty non-progressive fellow eyes of 50 keratoconus patients who underwent corneal cross-linking treatment for the other progressive eyes (group 1), 50 eyes of 50 keratoconus patients who were followed up as bilateral non-progressive keratoconus (group 2), and 50 eyes of 50 control subjects (group 3) were included in this retrospective study. Topographic, topometric, and Belin-Ambrósio Enhanced Ectasia Display-III indices were recorded at baseline and after six months.

RESULTS

Groups were similar in terms of age and gender. The changes in topographic parameters and topometric indices were similar among the three groups (p > 0.05 for all values). The maximum pachymetric progression index (PPI_max), maximum Ambrósio relational thickness (ART_max), and final D significantly increased at sixth-months in group 1 (p < 0.001, p = 0.004, and p = 0.02 respectively) but did not change in groups 2 and 3 (p > 0.05 for all values). ART_max, PPI_max, and final D value changes indicated a statistically significant difference among the groups using the one-way ANOVA test (p = 0.03, p = 0.007, and p = 0.03 respectively). The Bonferroni posttest revealed that these values increased at a higher rate in group 1 than in group 2 (p = 0.03, p = 0.01, and p = 0.04 respectively) and group 3 (p = 0.04, p = 0.03, and p = 0.04, respectively).

CONCLUSIONS

Fellow eyes of keratoconus patients who have underwent CXL for their progressive eyes may be more prone to progress than the patients who have no progression in both eyes. Screening unilateral non-progressive patients more closely than those with bilateral non-progressive patients and evaluating the changes in final D, ART_max, and PPI_max values may be helpful in the follow up of non-progressive keratoconus.