Atypical presentation of peripheral posterior lenticonus and role of multi-modal ocular imaging in its diagnosis and management

A 6-year-old systemically healthy child presented with visual acuity of 1/60, N18 oculusdextrus (OD), and 6/18, N6 oculus sinister (OS). Slit-lamp biomicroscopy revealed suspicious bilateral inferotemporal pigmented ciliary body (CB) tumour, protruding posterior capsule and temporal posterior subcapsular cataract oculus uterque. Anterior segment optical coherence tomography, ultrasonography, ultrasonic biomicroscopy and Scheimpflug imaging revealed protruding posterior capsule and cortex abutting but not arising from CB suggestive of peripheral pigmented posterior lenticonus with hypermetropia (axial length 20.27 mm OD and 19.97 mm OS). Aberrometry revealed high internal aberrations and low Dysfunctional Lens Index (DLI). Lens aspiration with intraocular lens implantation in the bag OD and contact lens correction OS were undertaken. The child had a postoperative visual gain of 3/60, N18 with improved aberrometric profile OD, and was advised amblyopia therapy. Rarely posterior lenticonus can mimic a CB mass. Multi-modal ocular imaging can aid in its diagnosis and management. DLI may serve as a useful indicator of surgery in such cases.

Repeatability of OCT Anterior Surface and Bowman's Layer Curvature and Aberrations in Normal and Keratoconic Eyes

PURPOSE

To study the repeatability of anterior surface and Bowman's layer curvature in normal and keratoconic eyes using optical coherence tomography (OCT).

METHODS

In this study, 96 normal and 96 keratoconic eyes underwent corneal imaging using Pentacam (Oculus Optikgeräte, Wetzlar, Germany) and OCT (Triton, Topcon Corporation, Tokyo, Japan). The elevation data from segmented air-epithelium (A-E) and epithelium-Bowman's layer (E-B) interfaces in OCT scans were used to quantify curvature and aberrations. The wavefront aberrations were evaluated with the ray tracing method and 6th order Zernike polynomials. The intraclass correlation coefficient (ICC), within-subject standard deviation (Sw), and coefficient of variation (CoV) were used to assess repeatability.

RESULTS

For curvatures, the Sw was less than 0.25 diopters (D) for the normal and keratoconic eyes. The Sw was highest for root mean square of lower order aberrations (0.14 µm) in keratoconic eyes. The CoV for curvatures was well below 0.5% for both groups. For some aberrations irrespective of groups, the CoV was greater because some individual aberrations (mean of three successive measurements) tended to be smaller in magnitude and even a small Sw resulted in a high CoV. For all variables, the ICC ranged between 0.80 and 0.99 for both the OCT and Pentacam measurements. Most variables were similar between the A-E and E-B interfaces (P > .05) for both groups. However, both differed significantly from all Pentacam variables (P < .05) in normal and keratoconic eyes.

CONCLUSIONS

The repeatability of OCT curvatures and aberrations compared well with the Pentacam indices for normal and keratoconic eyes. [J Refract Surg. 2020;36(4):247-252.].

Correlation of higher order aberrations in the anterior corneal surface and degree of keratoconus measured with a Scheimpflug camera

OBJECTIVE

To determine the correlation of higher order aberrations in anterior corneal surface and degree of keratoconus measured with a Scheimpflug camera.

MATERIAL AND METHODS

A descriptive, cross-sectional study was conducted on 152 eyes (both eyes of each patient) of patients with keratoconus, from January 2009 to April 2014. An examination was performed on the corneal aberrometry in the anterior corneal surface, and topographic mapping (by Amsler and Muckenhirn classification) was used to determine the degree of keratoconus. The correlation between high-order aberrations in anterior corneal surface and the degree of keratoconus was determined.

RESULTS

Coma aberration significantly correlated with keratoconus severity (r=.60, P<.01), as well as with the high order aberration (r=.61, P<.01). Trefoil and keratoconus were weakly correlated (r=.34, P<.01).

CONCLUSION

Higher order aberrations in anterior corneal surface were positively correlated with the degree of keratoconus in a similar way to the entire optical system.