Clinical, Demographic, and Tomographic Aspects Related to Iris Mammillations Among Patients With Keratoconus: A Cross-Sectional Study

PURPOSE

Iris mammillations (IM) were previously described in patients with keratoconus, but the clinical implications of this finding have never been studied. Our aim was to investigate demographic, tomographic, and clinical characteristics potentially associated with the presence of IM among patients with keratoconus.

METHODS

This was a cross-sectional study performed among patients with keratoconus in a public-affiliated university hospital. All patients under follow-up were considered eligible to participate in the study. Participants were evaluated by 2 trained ophthalmologists and submitted to corneal tomography (Pentacam). Selected demographic, clinical, and tomographic characteristics were assessed and compared among participants with IM (IM group) and without IM (No-IM group) using the Wilcoxon test or 2-tailed Fisher exact test, as appropriate.

RESULTS

The study population consisted of 106 subjects and 19 (17.9%) presented with IM. The median age and interquartile range were 18 years old (14-24) in the IM group and 20 years old (17-24) in the No-IM group (P = 0.135). The female proportion was 47.3% in the IM group and 52.8% in the No-IM group (P = 0.801). Median (interquartile ranges) pachymetric values of the right eyes were 498 (466-525) for the IM group and 459 (421-482) for the No-IM group (P = 0.005). For the left eyes, the values were 490 (456-523) in the IM group and 450 (418-485) in the No-IM group (P = 0.024).

CONCLUSIONS

Subjects with keratoconus presenting with IM have thicker corneas than those without IM. Follow-up studies should be performed to evaluate the clinical implications of this finding.

Are iris mammillations correlated with keratoconus?

Purpose

To describe the presence of iris mammillations (IM) in keratoconus.

Design

Retrospective case series and literature review.

Observations

This is a retrospective case series of eight patients presenting with keratoconus and IM, who were examined between January 2016 and December 2017 in the ophthalmology outpatient clinic. They had a median age of 14 (11–30), and all had bilateral keratoconus and diffusely distributed IM. The IM had similar presentations and similar iris colors. None had relevant medical or family diseases associated with IM. Three eyes previously had penetrating keratoplasty. Four (31%) out of 13 eyes had mean keratometry (Km) > 55D, and 4 (31%) had the thinnest pachymetry between 300 and 400μm.

Conclusions and importance

To the best of our knowledge, this is the first time that IM was observed in association with keratoconus patients. The possibility that IM is an early finding in otherwise healthy patients may help to predict the future diagnosis of keratoconus. Future studies are needed to show the frequency and possible association between IM and a keratoconus prognosis. This may also demonstrate that there is a subgroup of patients with a distinct etiology of keratoconus.

Validity of autorefractor based screening method for irregular astigmatism compared to the corneal topography- a cross sectional study

AIM

To present a method of screening for irregular astigmatism with an autorefractor and its determinants compared to corneal topography.

METHODS

This cross-sectional validity study was conducted in 2013 at an eye hospital in Spain. A tabletop autorefractor (test 1) was used to measure the refractive status of the anterior surface of the cornea at two corneal meridians of each eye. Then corneal topography (test 2) and Bogan's classification was used to group eyes into those with regular or no astigmatism (GRI) and irregular astigmatism (GRII). Test 1 provided a single absolute value for the greatest cylinder difference (Vr). The receiver operating characteristic (ROC) were plotted for the Vr values measured by test 1 for GRI and GRII eyes. On the basis a Vr value of 1.25 D as cut off, sensitivity, specificity were also calculated.

RESULTS

The study sample was comprised of 260 eyes (135 patients). The prevalence of irregular astigmatism was 42% [95% confidence interval (CI): 36, 48]. Based on test 2, there were 151 eyes in GRI and 109 eyes in GRII. The median Vr was 0.75 D (25% quartile, 0.5 D) for GRI and 1.75 D (25% quartile, 1.25 D) for GRII. The area under curve was 0.171 for GRI and 0.83 for GRII. The sensitivity of test I was 78.1% and the specificity was 76.1%.

CONCLUSION

A conventional autorefractor can be effective as a first level screening method to detect irregular corneal astigmatism in places where corneal topography facilities are not available.