Background: The refractive outcome of thermokeratoplasty for astigmatism correction depends upon the optical zone diameter (OZD) and coagulation angle (CA; distance between two coagulation spots around the flat meridian).
Methods: Astigmatism was induced in 36 spherical human eye-bank eyes (Ho:YAG laser, 15 Hz, 20 mJ/pulse, 25 pulses per coagulation spot) with different OZDs and CAs. Thirty eyes received free-hand laser application (marked positions). Six eyes were treated using a suction mask, providing a constant OZD of 8.1 mm and an angle of 22.5 degrees between the laser spots. To compare the results, silicone replicas of the eyes were made pre- and postoperatively and analyzed by video-topometery.
Results: With an average decrease of 4 D/mm the refractive change is inversely linear to the OZD. Changes of the CA showed significant variations between 22.5 degrees and 45 degrees, only. Mask guidance leads to the same amount of average refractive change. The deviation is +/- 3.4 D for the freehand application but only +/- 0.8 D for mask guidance.
Conclusion: The data obtained in this in vitro study are transferred to a treatment nomogram describing the immediate postoperative refractive change, not identical with the final refraction. The results of the study are limited by the fact that astigmatism was induced in spherical corneas, rather than correcting preexisting ones.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1007/s004170050097 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Evaluation of Eye Alignment Before and After Refractive Surgery Using an Implantable Collamer Lens in Phakic Patients with Myopia.
J Binocul Vis Ocul Motil
January 2025
Eye Center, Sanno Hospital, Tokyo, Japan.
Purpose: To investigate changes in eye alignment before and after ICL implantation in patients with myopia having corrected distance visual acuity (CDVA) of ≥0.0 logMAR.
Subjects And Methods: The medical records of 1012 patients without eye movement limitation who underwent bilateral ICL implantation were retrospectively reviewed a at the Eye Center of Sanno Hospital in Japan.
Temporal impacts of diverse concentrations of pilocarpine ophthalmic solution on human accommodation.
Clin Exp Optom
January 2025
Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China.
Clinical Relevance: Accommodation is crucial for clear near vision and is predominantly affected by presbyopia. The ability to modulate accommodative function with eye drops could offer a pharmacological approach to manage presbyopia.
Background: To investigate the effects of different concentrations of pilocarpine eye drops on ocular accommodation in young volunteers.
Crystalline lens power and astigmatism calculation in myopia by swept-source optical coherence tomography: A pilot study.
Graefes Arch Clin Exp Ophthalmol
January 2025
National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, 618# Fengqi East Road, Hangzhou, 310000, Zhejiang, China.
Purpose: To calculate the crystalline lens power and astigmatism, as well as their changes following cycloplegia, in individuals with myopia using swept-source optical coherence tomography (SS-OCT).
Methods: Participants were divided into two groups according to axial length (AL). Crystalline lens parameters, including power, lens thickness (LT), anterior chamber depth (ACD), and astigmatism, were measured with SS-OCT and analysed before and after cycloplegia.
Meta-analysis of retinal transcriptome profiling studies in animal models of myopia.
Front Med (Lausanne)
January 2025
Department of Ophthalmology, Emory University, Atlanta, GA, United States.
Objective: Myopia prevalence is increasing at alarming rates, yet the underlying mechanistic causes are not understood. Several studies have employed experimental animal models of myopia and transcriptome profiling to identify genes and pathways contributing to myopia. In this study, we determined the retinal transcriptome changes in response to form deprivation in mouse retinas.
View Article and Find Full Text PDFOptical properties of InGaN/GaN red quantum well(QW) and their microcavities were studied and compared under optical pumping. Incidence of the excitation laser from the p-side was employed for both structures in order to acquire better emission characteristics. The QW structure was grown on sapphire substrate by metalorganic vapor-phase epitaxy(MOVPE) with a blue pre-layer QW.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!