Revisiting Pentacam Parameters in the Diagnosis of Subclinical and Mild Keratoconus Based on Different Grading System Definitions

Objectives: To retest the performance of Pentacam parameters in the detection of eyes with subclinical keratoconus (KC) and mild KC based on different definitions from the Amsler-Krumeich (AK), Collaborative Longitudinal Evaluation of Keratoconus (CLEK), and ABCD systems. Materials and Methods: This cross-sectional university-based study comprised 24 eyes with subclinical KC, 144 eyes with mild KC (based on AK in 101 eyes, CLEK in 28 eyes, and ABCD in 15 eyes), and 70 controls. Diagnostic ability of the thinnest point (TP) pachymetry, KISA% index, inferior-superior asymmetry, corneal aberrations, Pentacam indices, front/back elevations, pachymetric progression index, Ambrósio-Relational Thickness (ARTmax), and Belin/Ambrósio Enhanced Ectasia Display scores (Df, Db, Dp, Dt, Da, and D-final) were evaluated. Results: ARTmax (83.3% sensitivity/74.3% specificity) had the highest ability in distinguishing subclinical KC from normal, followed by TP pachymetry, Dt, and Da. D-final showed excellent sensitivity/specificity in mild KC diagnosis based on AK (98%/100%) and CLEK (97.4%/100%) descriptions. In the mild KC-ABCD group, index of vertical asymmetry accurately detected all eyes with mild KC and 97.1% of the controls. Conclusion: This study points out the gray zone in the detection of eyes with subclinical and mild KC due to overlapping terminology and grading criteria. Pentacam parameters seem to have modest capability in subclinical KC detection, indicating the necessity for additional diagnostic modalities. However, eyes with mild KC can be diagnosed with high accuracy using Pentacam parameters, although the strongest parameters may vary according to the definition of "mild KC." Nevertheless, uniform and definitive criteria for subclinical and clinical KC classification are required for a diagnostic and therapeutic consensus in KC.

Increased epithelial backscatter: A novel finding in subclinical and clinical keratoconus.

BACKGROUND: To assess alterations in backscatter from the corneal epithelium, anterior stroma and lens surface in eyes with subclinical, mild and moderate keratoconus (KC). METHODS: In this single-centre, cross-sectional study involving 24 eyes with subclinical KC, 107 eyes with manifest KC (mild = 40 and moderate = 67 eyes) and 90 controls, line densitometry was performed with Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany) to obtain simultaneous backscatter values for the corneal epithelium, anterior stroma and anterior lens surface. Backscatter values and Pentacam parameters were used in subsequent statistical analyses. RESULTS: Eyes with subclinical, mild and moderate KC had similar epithelial and stromal backscatter (P > 0.05) that was significantly increased compared with the controls (P < 0.05). Although anterior lens surface backscatter did not differ between the control and KC groups (P > 0.05), it was significantly higher in the mild and moderate KC groups than in the subclinical KC group (P < 0.05). In the KC group (n = 131) epithelial backscatter was strongly correlated with stromal backscatter (r = 0.911, P < 0.0001). CONCLUSIONS: Increased epithelial backscatter and a strong correlation with anterior stromal backscatter in the KC groups were consistent with the epithelium-stroma interaction involved in KC pathogenesis. Single-point backscatter analysis can be used with point clouds to construct epithelial and stromal backscatter maps in Pentacam to aid the detection of KC as a novel feature.

Severe Intraocular Inflammation following Hydrophilic Acrylic Phakic Intraocular Lens Implantation in A Case with Concealed History of COVID-19: A Case Report and Literature Review.

Purpose: To firstly present management of toxic anterior segment syndrome (TASS) and possible postoperative endophthalmitis (POE) after implantation of a new hydrophilic-acrylic posterior chamber (PC) phakic intraocular lens (pIOL) in a case with undeclared history of COVID-19.Methods: A 21-year-old male without known disease represented severe anterior chamber inflammation (hypopyon), poor vision and corneal edema without vitreous involvement (TASS) at 24-hours after PC-pIOL implantation for unilateral high myopia (amblyopic).Results: Preoperative best-corrected visual acuity (BCVA) was 0.2 OS (-13 diopters). At 56-hours, vitreous was involved with visual loss indicating POE. The patient confessed that he had COVID-19 1-month ago. COVID-19 immunoglobulin M/G tests were positive, while other markers were negative. Intracameral/intravitreal antibiotics were applied. BCVA was 0.15 without hypopyon at 24-hours. Cultures were negative. Final BCVA was 0.6 with normal examination.Conclusion: TASS/POE etiology could not be demonstrated in this case, whereas COVID-19-related proinflammatory systemic background could have effect on triggering/aggravating this scenario.].