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.].

Corneal aberrations measured with a high-resolution Scheimpflug tomographer: repeatability and reproducibility.

PURPOSE: To evaluate the precision of elevation and wavefront aberration measurements with the Pentacam HR (Oculus Optikgeräte GmbH). SETTING: Flinders University, Australia. DESIGN: Instrument evaluation study. METHODS: A randomly selected eye of 100 participants was scanned twice with the Pentacam HR by 1 observer on the 3 measurement modes: 25-picture, 50-picture, and cornea fine. A second observer performed 2 scans on the same random eye with the 25-picture mode. Repeatability and reproducibility were assessed using the within-subject SD (Sw) statistic from a 1-way analysis of variance. RESULTS: From the 100 scanned eyes, the higher-order aberration root mean square (RMS) repeatability limit for both elevation and wavefront, and anterior and posterior measurements was 0.03 µm for all 3 measurement modes. Anterior, posterior, and total corneal wavefront Zernike terms were highly precise, with most Zernike terms displaying a repeatability limit of 0.03 µm. The least repeatable measurement was the posterior elevation Zernike term with the 25-picture scan (repeatability limit 1.50 µm). The cornea fine measurement mode provided the most precise measurements. Reproducibility limits (second observer) were similar to repeatability limits with the 25-picture scan mode. CONCLUSIONS: The Pentacam HR provided highly precise aberration outputs. The most precise measurements are achievable with the cornea fine measurement mode and wavefront aberrations. One should be cognizant of posterior elevation aberration precision, particularly for lower radial order and higher azimuthal frequency terms. Accounting for tilt and misalignment of aberrations, all RMS and Zernike aberrations were extremely precise (repeatability and reproducibility limit less than 0.000001 µm).

Quantitative Analysis of Objective Forward Scattering and Its Relevant Factors in Eyes with Cataract.

This study was aimed to quantitatively assess objective forward scattering and its relevant factors in eyes having cataract. Our study comprised 192 eyes of 192 patients (mean age, 71.3 ± 9.2 (standard deviation) years) who have cataract formation for surgical consultation. We determined uncorrected and corrected distance visual acuities (UDVA and CDVA), manifest refraction, the grade of nuclear sclerosis, objective scattering index (OSI) with the OQAS II (Visiometrics, Spain), log(s) with the C-Quant (Oculus, Germany), and ocular higher-order aberrations (HOAs) using the wavefront sensor (KR-1W, Topcon, Japan). The mean OSI was 5.11 ± 3.19 (0.90 to 20.90). We found explanatory variables relevant to the OSI to be, logMAR CDVA (p < 0.0001, partial regression coefficient B = 5.917) and log(s) (p = 0.0006, B = 0.911) (adjusted R2 = 0.333), in order of influence. No significant correlation was found with other clinical factors such as gender, age, manifest refraction, UDVA, ocular HOAs, or nuclear sclerosis. Eyes with worse CDVA and higher log(s) are more predisposed to show higher OSI in cataractous eyes. It is suggested that objective forward scattering was associated, not only with CDVA, but also with subjective forward scattering, in cataractous subjects.

Scheimpflug lens densitometry and ocular wavefront aberrations in patients with mild nuclear cataract.

PURPOSE: To test correlations between Scheimpflug optical densitometry and ocular higher-order aberrations (HOAs) in patients with mild nuclear cataract. SETTING: Cornea and Refractive Surgery Department, Hospital de Braga, Braga, Portugal. DESIGN: Retrospective single-center study. METHODS: In eyes with mild nuclear cataract, lens densitometry was evaluated by Scheimpflug imaging (Pentacam HR), which provided an objective quantification (mean density and maximum density) and grading (nuclear staging score) of the crystalline lens. A visual function analyzer that combines ray-tracing aberrometry and Placido disk-based topography (iTrace) was used to evaluate the total ocular and internal HOAs. RESULTS: The study comprised 40 eyes of 30 patients. The mean density of the lens nucleus was 8.99% ± 0.76% (SD) (range 7.5% to 10.8%), and the mean maximum density was 27.96% ± 6.97% (range 16.9% to 56.1%). Regarding the score of nuclear staging of the Scheimpflug device, 28 eyes had level 0 and 12 eyes had level 1. Significant positive correlations were found between the mean density and maximum density parameters and the internal HOAs (ρ = 0.661, P < .001 and ρ = 0.570, P < .001, respectively). CONCLUSIONS: There were significant correlations between the quantification parameters derived from Scheimpflug lens densitometry and ocular HOAs. The integration of these technologies can help in clinical decision making and in understanding the subjective symptoms of patients with mild nuclear cataracts. FINANCIAL DISCLOSURE: Dr. Ambrósio is a consultant to Oculus Optikgeräte GmbH, Alcon Surgical, Inc., and Carl Zeiss Meditec AG. None of the other authors has a financial or proprietary interest in any material or method mentioned.

Correlation of higher order aberrations in the anterior corneal surface and degree of keratoconus measured with a Scheimpflug camera. / Correlación de aberraciones de alto orden en la cara anterior de la córnea y el grado de queratocono medidas con cámara de Scheimpflug.

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.

Very high-frequency digital ultrasound evaluation of topography-wavefront-guided repair after radial keratotomy.

We report a topography-wavefront-guided repair procedure in a patient with a decentered optical zone and significant higher-order aberrations (HOAs) following radial keratotomy 14 years previously. The CRS-Master custom ablation software was used to generate a topography-wavefront-guided ablation profile based on Atlas front corneal surface topography data, and the MEL 80 excimer laser was used to treat the patient. Very high-frequency digital ultrasound scanning (Artemis) was performed before and after surgery to measure epithelial and stromal thickness changes to evaluate the anatomical congruity of the planned and achieved irregular ablation. Nine months postoperatively, the optical zone centration was topographically improved and HOAs were significantly lower, with a 90% reduction in spherical aberration. The stromal thickness change map demonstrated that the profile of stromal tissue removed matched the irregular ablation profile. However, the measured stromal thickness change at the maximum point was 33% higher than the predicted ablation depth. The epithelial thickness change measured in this case indicates that topography-guided treatments could be improved by taking epithelial thickness changes into account.