The Gaussian formula and spherical aberration of the static and moving curved mirrors from Fermat's principle

The Gaussian formula and spherical aberrations of the static and relativistic curved mirrors are analyzed using the optical path length (OPL) and Fermat's principle. The geometrical figures generated by the rotation of conic sections about their symmetry axes are considered for the shapes of the mirrors. By comparing the results in static and relativistic cases, it is shown that the focal lengths and the spherical aberration relations of the relativistic mirrors obey the Lorentz contraction. Further analysis of the spherical aberrations for both static and relativistic cases have resulted in the information about the limits for the paraxial approximation, as well as for the minimum speed of the systems to reduce the spherical aberrations.Comment: 15 pages, 7 figures, uses iopart. Major revisions on the physical interpretations of the results. Accepted for publication in J. Op

Measuring benefits and patients' satisfaction when glasses are not needed after cataract and presbyopia surgery: scoring and psychometric validation of the Freedom from Glasses Value Scale (FGVS©)

<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to reduce the number of items, create a scoring method and assess the psychometric properties of the Freedom from Glasses Value Scale (FGVS), which measures benefits of freedom from glasses perceived by cataract and presbyopic patients after multifocal intraocular lens (IOL) surgery.</p> <p>Methods</p> <p>The 21-item FGVS, developed simultaneously in French and Spanish, was administered by phone during an observational study to 152 French and 152 Spanish patients who had undergone cataract or presbyopia surgery at least 1 year before the study. Reduction of items and creation of the scoring method employed statistical methods (principal component analysis, multitrait analysis) and content analysis. Psychometric properties (validation of the structure, internal consistency reliability, and known-group validity) of the resulting version were assessed in the pooled population and per country.</p> <p>Results</p> <p>One item was deleted and 3 were kept but not aggregated in a dimension. The other 17 items were grouped into 2 dimensions ('global evaluation', 9 items; 'advantages', 8 items) and divided into 5 sub-dimensions, with higher scores indicating higher benefit of surgery. The structure was validated (good item convergent and discriminant validity). Internal consistency reliability was good for all dimensions and sub-dimensions (Cronbach's alphas above 0.70). The FGVS was able to discriminate between patients wearing glasses or not after surgery (higher scores for patients not wearing glasses). FGVS scores were significantly higher in Spain than France; however, the measure had similar psychometric performances in both countries.</p> <p>Conclusions</p> <p>The FGVS is a valid and reliable instrument measuring benefits of freedom from glasses perceived by cataract and presbyopic patients after multifocal IOL surgery.</p

The effect of different optical zone diameters on the results of high-order aberrations in femto-laser-assisted in situ keratomileusis

Purpose: To evaluate the postoperative high-order aberration differences of femto-LASIK surgery in 6.5 and 7?mm optic zones. Patients and Methods: We retrospectively reviewed 80 eyes of 40 patients with myopia or myopia with astigmatism who underwent femtosecond LASIK surgery. Q values, z3, 3 (h. trefoil), z3, –3 (v. trefoil), z3, 1 (h. coma), z3, –1 (vertical coma), z4, 0 (spherical aberration), z5, –1 (second other v. coma), aberration coefficients were evaluated 3?months after surgery. Central corneal thicknesses, intraocular pressures, patient ages and genders, optical zone diameters and ablation depths are collected from patients’ medical records. Results: The mean age was 28.4?±?0.69?years (range, 20–47?years). Lower z4, 0 spherical aberrations and aberration coefficient values were associated with larger optical zones (7?mm) (z4, 0 spherical aberrations?=?1.25, p?=?0.01; coefficient value?=?–1.21, p?<?0.01). Although a smaller optical zone (6.5?mm) was associated with an increase in most of the wave-front aberration variables, measurements were not statistically different between the two groups other than z4, 0 spherical aberrations and aberration coefficients. Discussion: LASIK treatment with 6.5 and 7?mm optical zones is safe and effective for correcting myopia and myopic astigmatism and has statistically similar visual outcomes. Moreover, larger optical zone (7?mm) was found to be associated with lower spherical aberration induction and smaller aberration coefficient values compared to 6.5?mm optical zone. This can be important for decision-making in femto-LASIK surgery for better postoperative results

Myopic outcomes after excimer laser phototherapeutic keratectomy (PTK)

Purpose: To evaluate refractive outcomes following excimer laser phototherapeutic keratectomy (PTK). Methods: A retrospective non-randomized review of refractive outcomes of 146 consecutive eyes treated with excimer laser PTK at the Rothschild Foundation, Paris, France. Inclusion criteria were all patients undergoing PTK laser using a flying spot excimer laser system (Wavelight Allegretto, Alcon Surgical, Inc.) from October 2016 to June 2018. Exclusion criteria were incomplete data, irregular astigmatism and dystrophies of uncertain diagnosis. Preoperative diagnoses included recurrent corneal erosion syndrome without dystrophy and Cogan corneal dystrophies. The primary outcome measure was the change in spherical equivalent (SEQ) at M1 post PTK. The secondary outcome measure was the creation of a regression equation for predicting refractive outcomes after PTK, by analyzing the effect of ablation depth (AD) and optical zone (OZ) diameter. Results: Fifty-eight eyes of 54 patients were included. The mean OZ was 7.352 mm±0.622. The mean AD was 18.362μm±21.406. At M1 postoperatively, the mean SEQ was -2.485 D±2.628 and mean final SEQ was -1.052 D±1.260. Both OZ and AD were independent variables with significant effects on the final visual outcome. A regression equation for predicting refractive outcomes was established. No complications were observed. Conclusion: The Wavelight flying spot excimer laser system produces myopic outcomes following PTK. Both OZ and AD are significant variables. A regression equation was created and may aid in prediction of refractive outcomes following PTK

Topical cyclosporine A in severe steroid-dependent childhood phlyctenular keratoconjunctivitis

PURPOSE: To assess the efficacy of topical cyclosporine A (CsA) in children with phlyctenular keratoconjunctivitis associated with severe steroid-dependent corneal inflammation. DESIGN: Prospective, noncomparative, interventional case series. METHODS: patients: Children with phlyctenular keratoconjunctivitis associated with severe steroid-dependent corneal inflammation and not responding to oral antibiotics (cyclines or erythromycin). intervention: Topical CsA 2% four times daily, initially combined with topical dexamethasone for the first week. main outcome measures: Efficacy was judged by the patients (symptoms and ocular redness) and by the ophthalmologist (ocular redness and corneal inflammation). The patients were monitored for adverse effects, and cyclosporinemia was determined every 3 months. RESULTS: We studied 11 children (13 eyes) with a mean age of 9 years (range, 4 to 15 years). Inflammation was controlled in all the eyes within 14 days. Inflammation did not recur during CsA monotherapy, during a mean follow-up of 12 +/- 8 months (range, 6 to 31 months). CsA therapy was stopped in eight patients (10 eyes) after a mean treatment duration of 13 +/- 9 months (range, 6 to 31 months), and no recurrences occurred during 10 +/- 3 months of follow-up (range, 6 to 12 months). Local tolerance of CsA was good. None of the patients had detectable CsA blood levels. CsA was withdrawn in one case after 6 months, because of generalized skin rash. CONCLUSIONS: Long-term topical CsA 2% therapy is safe and effective in children with phlyctenular keratoconjunctivitis associated with severe steroid-dependent corneal inflammation

Topical cyclosporine A in severe steroid-dependent childhood phlyctenular keratoconjunctivitis

PURPOSE: To assess the efficacy of topical cyclosporine A (CsA) in children with phlyctenular keratoconjunctivitis associated with severe steroid-dependent corneal inflammation. DESIGN: Prospective, noncomparative, interventional case series. METHODS: patients: Children with phlyctenular keratoconjunctivitis associated with severe steroid-dependent corneal inflammation and not responding to oral antibiotics (cyclines or erythromycin). intervention: Topical CsA 2% four times daily, initially combined with topical dexamethasone for the first week. main outcome measures: Efficacy was judged by the patients (symptoms and ocular redness) and by the ophthalmologist (ocular redness and corneal inflammation). The patients were monitored for adverse effects, and cyclosporinemia was determined every 3 months. RESULTS: We studied 11 children (13 eyes) with a mean age of 9 years (range, 4 to 15 years). Inflammation was controlled in all the eyes within 14 days. Inflammation did not recur during CsA monotherapy, during a mean follow-up of 12 +/- 8 months (range, 6 to 31 months). CsA therapy was stopped in eight patients (10 eyes) after a mean treatment duration of 13 +/- 9 months (range, 6 to 31 months), and no recurrences occurred during 10 +/- 3 months of follow-up (range, 6 to 12 months). Local tolerance of CsA was good. None of the patients had detectable CsA blood levels. CsA was withdrawn in one case after 6 months, because of generalized skin rash. CONCLUSIONS: Long-term topical CsA 2% therapy is safe and effective in children with phlyctenular keratoconjunctivitis associated with severe steroid-dependent corneal inflammation