Intraocular Lens Power Calculations in Keratoconus Eyes Comparing Keratometry, Total Keratometry, and Newer Formulae.

PURPOSE: To compare the utility of keratometry vs total keratometry (TK) for intraocular lens power calculations in eyes with keratoconus (KCN) using KCN and non-KCN formulae. DESIGN: Retrospective cohort study. METHODS: This study was conducted at 2 academic centers and included 87 eyes in 67 patients who underwent cataract surgery between 2019 and 2021. Biometry measurements were obtained using a swept-source optical coherence tomography biometer (IOL Master 700). Refractive prediction errors, including root mean square error (RMSE), were calculated for 13 formulae. These included 4 classical formulae (Haigis, Hoffer Q, Holladay 1 [H1], and SRK/T), 5 new formulae (NF) (Barrett Universal II [BU2], Cooke K6, EVO 2.0, Kane, and Pearl-DGS), 3 KCN formulae (BU2 KCN: M-PCA, BU2 KCN: P-PCA, and Kane KCN), and H1 with equivalent keratometry reading values (H1-EKR). Formulae were ranked by RMSE. Friedman analysis of variance with post hoc analysis and H-testing was used for statistical significance testing. RESULTS: KCN formulae had the lowest RMSEs in all eyes, and BU2 KCN:M-PCA performed the best among KCN formulae in all subgroups. In eyes with severe KCN, if TK values are unavailable, the BU2 KCN: P-PCA performed better than the top-ranked non-KCN formula (SRK/T). In eyes with nonsevere KCN, if TK values are unavailable, EVO 2.0 K was statistically superior to the next competitor (Kane K). H1-EKR had the highest RMSE. CONCLUSIONS: KCN formulae and TK are useful for intraocular lens power calculations in KCN eyes, especially in eyes with severe KCN. The BU2 KCN: M-PCA using TK values performed best for eyes with all severities of KCN. For eyes with nonsevere KCN, the EVO 2.0 TK or K can also be used.

Frugal Method of Notch Modification of Scleral Contact Lenses in the Setting of Complex Ocular Surface Anatomy.

ABSTRACT: Scleral contact lenses (ScCLs) have gained popularity as a treatment of refractive errors in patients with complex anterior segment pathology. Patients with mechanical abnormalities of the ocular surface may be unsuccessful with traditional ScCL fitting. Scleral contact lens modifications, such as notching and microvaulting, typically incur additional financial costs and require the services of professional laboratories. We describe a frugal method of ScCL notch modification that can be performed by a practitioner using readily available tools in a single office visit. Two patients with abnormal ocular surface anatomy were fit with the practitioner-modified ScCL and achieved successful visual rehabilitation. We offer this method as a potentially economical and effective technique to achieve successful ScCL fitting in this challenging patient population with pathologies that may preclude standard ScCL usage.

Comparative biomechanics of hagfish skins: diversity in material, morphology, and movement.

The baggy skins of hagfishes confer whole-body flexibility that enables these animals to tie themselves into knots without injury. The skin's looseness is produced by a subcutaneous blood sinus that decouples the skin and body core and permits the core to contort dramatically without loading the skin in tension or shear. Hagfish skin represents a biological composite material comparable in strength and stiffness to the conventionally taut skins of other fishes. However, our understanding of hagfish skin is restricted to only one of 78 species: The Pacific hagfish Eptatretus stoutii. To determine if other hagfish share similar characteristics with E. stoutii, we measured material properties and compared histological data sets from the skins of four hagfish species: E. springeri, E. stoutii, Myxine glutinosa, and M. hubbsi. We also compared these material properties data with skins from the American eel, Anguilla rostrata. We subjected skin samples from all species to uniaxial tensile tests in order to measure strength, stiffness, extensibility, and toughness of skins stretched along longitudinal and circumferential axes. We also used a series of equibiaxial tensile tests on skin samples from E. stoutii, M. glutinosa, and A. rostrata to measure stiffness of skins simultaneously strained along both axes. Significant results of uniaxial and biaxial tests show that the skins from Eptatretus are anisotropic, being stiffer in the longitudinal axis, and more extensible than the isotropic skins of Myxine. Skins of A. rostrata were stiffer in the circumferential axis and they were stronger, tougher, and stiffer than all hagfish skins examined. The skins of Eptatretus are histologically distinct from Myxine skins and possess arrays of fibers that stain like muscle. These interspecific differences across hagfish skins show a phylogenetic pattern with knotting kinematics and flexibility; both genera belong to distinct but major subfamilies within the Myxinidae, and Eptatretus is known for creating and manipulating a greater diversity of knotting styles than Myxine.

The origin of regional failure in oral cavity squamous cell carcinoma with pathologically negative neck metastases.

IMPORTANCE: Squamous cell carcinoma of the oral cavity (OSCC) is a common malignant tumor worldwide. OBJECTIVE: To determine if regional failure in patients with OSCC and pathologically negative neck nodes (pN-) is due to an incomplete sampling procedure during surgery. DESIGN, SETTING, AND PARTICIPANTS: We retrospectively reviewed the medical records of 2258 patients from 11 cancer centers worldwide who underwent neck dissection for OSCC (1990-2011) and who were pN-. Of those, 345 had clinical evidence of nodal metastases (cN+) on radiologic workup. The neck specimens were available for reanalysis in 193 patients. Survival rates were calculated using the Kaplan-Meier graphs and analyzed by multivariable analysis. MAIN OUTCOMES AND MEASURES: Five-year overall survival (OS), disease-specific survival (DSS), and disease-free survival (DFS). RESULTS: Resectioning and analysis of the neck dissection specimens in the cN+/pN- subgroup revealed false-negative results in 29 (15%) of 193 patients. The negative predictive value of the initial pathologic examination was 85%. The 5-year OS and DSS in the cN-/pN- group were 77.6% and 87.2%, respectively. The 5-year OS and DSS of the cN+/pN- group were 62.6% and 78.5%, respectively (P < .001). In multivariable analysis, cN+ classification was significantly associated with poor OS (hazard ratio [HR], 1.7; 95% CI, 1.1-3.8; P = .03) and poor DSS (HR, 1.46; 95% CI, 1.1-4.1; P = .04). A cN+ classification was associated with lower DFS (66.3% vs 76.2%; P = .05) and lower regional recurrence-free survival (68.6% vs 78.8%; P = .02) but not with local (P = .20) or distant recurrence (P = .80). CONCLUSIONS AND RELEVANCE: Pathologic staging underestimates the incidence of nodal metastases in cN+ disease. After correction for pathologically missed nodal metastases, radiologic evidence of neck nodes is an independent predictor of outcome, suggesting that traditional sampling during surgery might miss metastases, and this fact might explain the origin of treatment failure in these patients.