RESUMO
PURPOSE: A method was developed to measure strabismic angles >50Δ by stacking commercially available Fresnel and block prisms in the same direction ("piggyback prisms"). METHODS: With a laser pointer (wavelength of 532 nm) as the light source, the deviation of the laser spot produced by the stacked prisms was measured on a tangent screen placed 100 cm away from the prisms. To the obtained data with combinations of Fresnel prisms (5Δ-40Δ) and block prisms (10Δ-50Δ), a cubic surface function was fitted by polynomial regression. RESULTS: The combined effect of stacked prisms was always greater than the arithmetic sum of the labeled values of two prisms (by up to 66Δ), increasing exponentially with each prism power and reaching the maximum of 156Δ for the Fresnel/block combination of 30Δ/50Δ. We obtained contour plots to evaluate the optically induced additivity error and constructed look-up tables for quickly determining the combined effect of the prisms based on their labeled values. CONCLUSIONS: Stacking prisms is a practical method to evaluate a large strabismic angle that cannot be measured by any single prism and is especially useful in dealing with severely paralytic strabismus.
RESUMO
PURPOSE: To evaluate the effect of smoking on the outcome of antivascular endothelial growth factor (VEGF) therapy in patients with neovascular age-related macular degeneration (nAMD). METHODS: This retrospective case-control study included 64 eyes in 59 patients with treatment-naïve nAMD. Smoking habits were obtained from hospital records and patient recall. The patients were divided into ever-smokers and never-smokers. The patients were treated with ranibizumab or aflibercept for at least 1 year. Outcome measures were best-corrected visual acuity (BCVA), central retinal thickness (CRT) at the fovea, subfoveal choroidal thickness (SCT), and number of injections received. RESULTS: There were no statistically significant differences in BCVA, CRT, or SCT changes between ever-smokers and never-smokers. The number of injections received was significantly higher in ever-smokers with a history of heavy smokers (never-smokers vs. heavy smokers: 5.3 ± 2.6/year vs. 7.3 ± 2.5/year; P=0.048 and mild smokers vs. heavy smokers: 5.2 ± 2.5/year vs. 7.3 ± 2.5/year; P=0.043). There was no significant difference in the baseline CRT or presence of atrophic retinal pigment epithelium in the fellow eyes of patients with nAMD according to smoking status; however, the baseline CRT in eyes with nAMD was significantly thinner in ever-smokers than in never-smokers (P=0.02). CONCLUSION: The anti-VEGF therapy was frequently required in nAMD patients with a history of heavy smoking. Heavy smoking could cause poor therapeutic response in nAMD patients.
