Análisis óptico del tratamiento PresbyLASIK: algoritmo de patrones de luz propagados

Comunicación presentada en la VIII Reunión Nacional de Óptica, Alicante, Septiembre 2006

Corneal aberrometric and refractive performance of 2 intrastromal corneal ring segment models in early and moderate ectatic disease

Purpose: To evaluate and compare visual, refractive, and corneal aberrometric outcomes after implantation of 2 types of intrastromal corneal ring segments (ICRS) in eyes with early to moderate ectatic disease. Settings: Vissum Corporation-Instituto Oftalmológico de Alicante, Alicante, Spain. Methods: This retrospective analysis comprised consecutive eyes with grade I or grade II corneal ectasia (keratoconus, pellucid marginal degeneration, ectasia after laser in situ keratomileusis) that had Intacs (Group I) or KeraRings (Group K) ICRS implantation using femtosecond technology. Visual, refractive, and corneal aberrometric outcomes were analyzed and compared between groups over a 6-month follow-up. Results: Group I had 17 eyes and Group K, 20 eyes. One month postoperatively, there was a statistically significant reduction in sphere in both groups (P≤.02). At 6 months, there was a statistically significant reduction in manifest cylinder in Group K that was consistent with the significant reduction in corneal astigmatic aberration (both P = .04). The uncorrected distance visual acuity increased significantly in Group K (P = .04) but not in Group I; 41.18% of eyes in Group I and 52.94% in Group K gained 1 or more lines of corrected distance visual acuity. Both groups had significant corneal flattening (P≤.02). At 1 month, the mean primary spherical aberration was −0.17 μm ± 0.52 (SD) in Group I and 0.40 ± 0.35 μm in Group K; the difference was statistically significant (P<.01). Conclusion: Astigmatism correction in early to moderate ectatic corneas was more limited with the Intacs ICRS, which induced negative primary spherical aberration in the initial postoperative period.Supported in part by a grant from the Spanish Ministry of Health, Instituto Carlos III, Red Temática de Investigación Cooperativa en Salud Patología Ocular del Envejecimiento, Calidad Visual y Calidad de Vida, Subproyecto de Calidad Visual (RD07/0062)

Intracorneal ring segment implantation in corneas with post-laser in situ keratomileusis keratectasia

Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.Purpose: To evaluate the refractive and aberrometric changes in corneas with post-LASIK keratectasia implanted with intracorneal ring segments (ICRS) during a 2-year follow-up. Design: Retrospective, consecutive case series. Participants: Thirty-four eyes of 25 patients (age range, 20–59 years) with post-LASIK ectasia were included. Ectasia was diagnosed by slit-lamp appearance of corneal thinning, unstable topographic steepening, progressive corneal thinning on ultrasonic pachymetry, decreased visual acuity, and unstable refraction. Methods: Intracorneal ring segment implantation was performed in all cases by 2 surgeons from 2 different ophthalmologic centers with the aim of correcting the spherocylindrical error and improving the visual quality. Corneal tunnels were created by means of mechanical dissection in 20 eyes and femtosecond laser technology in 14 eyes. Intacs (Addition Technology, Inc, Fremont, CA) were inserted in 24 eyes, and KeraRings (Mediphacos, Belo Horizonte, Brazil) in 10 eyes. In all cases a follow-up of 12 months was completed, with a total of 15 eyes examined 24 months after surgery. Main Outcome Measures: Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, keratometry, and corneal aberrations. Results: Uncorrected visual acuity did not improve after surgery (P = 0.17). Best spectacle-corrected visual acuity increased significantly at 6 months (P = 0.02). Some 38.89% of eyes gained 2 or more lines of BSCVA at 6 months, and this percentage increased to 60% at 24 months. There was a nonsignificant reduction of sphere at 6 months (P = 0.28). Manifest cylinder was reduced significantly during the postoperative follow-up (P = 0.05, preoperative to 6 months; P = 0.04, 6–12 months). The cornea was on average flatter at 6 months (P<0.01), with a posterior nonsignificant regression of the achieved flattening (P = 0.73). In regard to corneal aberrations, a statistically significant reduction was found in coma-like root mean square (RMS) (P = 0.03) after surgery. Segment ring explantation was performed in 6 eyes, and ring reposition was performed in 2 eyes. The apical curvature gradient was significantly higher in the group of explanted eyes (P = 0.03). Conclusions: Intracorneal ring segment implantation is a useful option for the treatment of coma-like aberrations and astigmatism in post-LASIK corneal ectasia.Supported in part by a grant of the Spanish Ministry of Health, Instituto Carlos III, Red Temática de Investigación Cooperativa en Salud “Patología ocular del envejecimiento, calidad visual y calidad de vida”, Subproyecto de Calidad Visual (RD07/0062)

Design and evaluation of intraocular lenses

En este trabajo se analiza el cálculo de la potencia de una lente intraocular de un ojo afáquico de gran tamaño así como el papel del factor de forma en la calidad de imagen de estos mismos ojos.The power calculation of an intraocular lens and the role of bending factor in image quality into aphakic long eye are analyzed in this paper

Light propagation through the eye: numerical considerations and applications to presbylasik surgery analysis

Trabajo presentado en el 3rd European Meeting in Physiological Optics, London, September 7-9, 2006.Transmittance evaluation of cornea. Transmittance evaluation of crystalline lens. Wave propagation (angular spectrum) up to the plane of interest. Applications to presbylasik surgery analysis

Optical analysis of PresbyLASIK treatment by a light propagation algorithm

PURPOSE: To evaluate the changes in the optical quality of corneas of hyperopic patients operated using central multifocal presbyLASIK treatment through the study of light patterns around the retinal plane. METHODS: This study included eight hyperopic eyes that underwent central presbyLASIK surgery with Presby-one software using an H. Eye Tech Technovision excimer laser platform. Mean patient age was 57 years. Mean preoperative spherical equivalent refraction was 1.28_0.87 diopters (D). Mean distance decimal visual acuity with correction was 1.02_0.13 and without correction was 0.37_0.15. The optical quality was characterized by the Strehl ratio, the spot size on the retina, and objective decimal visual acuity calculated based on measured corneal topography using Fresnel propagation algorithm based on a realistic eye model. RESULTS: The postoperative spherical equivalent refraction was _0.55_0.48 D. The distance decimal visual acuity with correction was 0.94 and without correction was 0.70. The pseudoaccommodation range was 1.60_0.40 D. A good Pearson correlation coeffi cient was obtained (r2=0.86) for the linear fi t between the real and calculated decimal visual acuity for the eight eyes. The Strehl ratio value on the retinal plane increased after the surgery by a mean factor of 4.7. CONCLUSIONS: With a complete characterization of the eye and a complete propagation algorithm (that takes into account all refractive surfaces in the eye at the same time), it is possible to evaluate the optical quality in eyes of patients who have undergone central presbyLASIK treatment.Conselleria de Empresa, Universitat i Ciència of the Generalitat Valenciana, through the project nr. GV04A/578, and by the Ministerio de Educación y Ciencia through the project nr. FIS2005-05053. Spanish Ministry of Health, Instituto Carlos III, Red Temática de Investigación en Oftalmologia, Subproyecto de Cirugia Refractiva y Calidad Visual (C03/13) and by a grant from the Spanish Generalitat Valenciana, ref: Grupos05/036 Grants and Support for scientific research and technological development in the Comunidad Valenciana for the year 200

Pseudoaccommodation and visual acuity with technovision PresbyLASIK and a theoretical simulated Array® multifocal intraocular lens

PURPOSE: To compare the visual results of presbyLASIK patients to the best theoretical pseudoaccommodation that could be achieved using a multifocal refractive intraocular lens (IOL) model based on the optical structure of a simulated AMO Array multifocal IOL. METHODS: The study included 10 hyperopic eyes that underwent central presbyLASIK surgery using a Technovision excimer laser platform. Mean patient age was 57 years, and mean preoperative spherical equivalent refraction was 1.28±0.87 diopters. The optical quality was evaluated by objective distance and near decimal visual acuities calculated using a Fresnel propagation algorithm based on a realistic eye model. Results of the presbyLASIK technique were compared with the theoretical results obtained for the same eye with an ideal, best-fit multifocal IOL (simulated Array multifocal IOL) substituted for the crystalline lens. RESULTS: For near objective visual acuity (from 25 cm to 1 m), the ideal, theoretical Array-like lens provided values of visual acuity above 0.5 for all object distances, whereas presbyLASIK also provided good visual responses for distances beyond 45 cm. For distance vision (from 1.5 to 6 m), both the IOL and presbyLASIK visual acuities were over 0.5, but the optical performance of the ideal Array-like lens was slightly worse than with presbyLASIK. CONCLUSIONS: Overall near to distance visual acuity obtained with the presbyLASIK technique is comparable to the best visual acuity that could be achieved with a simulated Array multifocal IOL. Near visual acuity with presbyLASIK falls off from the ideal.This study was supported in part by a grant of the Spanish Ministry of Health, Instituto Carlos III, Red Temática de Investigación en Oftalmología, Subproyecto de Cirugía Refractiva y Calidad Visual (C03/13) and by the Ministerio de Educación y Ciencia through the project nr FIS2005-05053