Background: We objectively assessed the optical quality and intraocular scattering by means of parameters provided by a clinical double-pass system in healthy young subjects and thereby we obtained new reference data for clinical diagnosis. We calculated normal values of neural contrast sensitivity function (nCSF) from the measured modulation transfer function (MTF) and the contrast sensitivity function (CSF).



Methods:  Eligible subjects were healthy adults aged from 18 to 30 years with a logMAR visual acuity (VA) of 0.0 or better and normal values of CSF. Optical quality measurements for a 4.0 mm pupil were performed using the Optical Quality Analysis System (OQAS) based on the double-pass technique. The following parameters were analysed: the modulation transfer function cutoff frequency (MTFcutoff), the Strehl2D ratio, the OQAS values (OV) at 100, 20 and nine per cent contrasts and the objective scatter index (OSI).



Results:  A total of 178 volunteers responded to the call, of whom 181 eyes were finally part of the study taking into account the criteria for inclusion. The values for the optical quality parameters were: 44.54 ± 7.14 cpd (MTFcutoff), 0.27 ± 0.06 (Strehl2D ratio), 1.48 ± 0.24 (OV100%), 1.58 ± 0.32 (OV20%), 1.64 ± 0.39 (OV9%), and 0.38 ± 0.19 (OSI). The nCSF calculated was 1.76 ± 0.21 (3 cpd), 2.13 ± 0.23 (6 cpd), 2.01 ± 0.28 (12 cpd) and 1.86 ± 0.33 (18 cpd).



Conclusion:  The normal values provided can be a useful tool for discriminating healthy eyes from early abnormal ones in which the optical quality or sensory function is impaired.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1444-0938.2010.00535.x

Optical quality and intraocular scattering in a healthy young population.

https://www.gatinel.com/wp-content/uploads/2013/01/Objective-Assessment-of-Crystalline-Lens-Opacity-Level-by-Measuring-Ocular-Light-Scattering-With-a-Double-Pass-System_2013_American-Journal-of-Ophthalmology.pdf

Objective Assessment of Crystalline Lens Opacity Level by Measuring Ocular Light Scattering With a Double-Pass System

Purpose To evaluate visual quality after laser in situ keratomileusis (LASIK) performed to achieve monovision in presbyopic patients. Setting Laboratory of Vision Sciences and Applications, Department of Optics, University of Granada, Granada, and Clinica Novovision, Madrid, Spain. Design Cohort study. Methods Laser in situ keratomileusis was performed with the Allegretto Wave Eye-Q 400 Hz laser. The dominant eye was corrected for far vision and the nondominant eye for near vision by targeting −1.25 diopters of myopia. The F-CAT algorithm was programmed targeting a postsurgical corneal asphericity of −0.80 in the dominant eye and −1.00 in the nondominant eye. Visual acuity, contrast sensitivity function, ocular aberrations, stereoacuity, the scattering index, and the visual-discrimination capacity were analyzed preoperatively and 3 months postoperatively. Results The study enrolled 25 patients (50 eyes) with a mean age of 49.3 years ± 4.5 (SD). Postoperatively, more than 90% of patients had a binocular uncorrected distance and near visual acuity of 0.0 logMAR or better, although the contrast sensitivity function diminished, especially in the nondominant eye and with binocular vision. Stereoacuity was significantly worse in all patients ( P P P =.614). In all eyes, the mean objective scatter index value increased postoperatively, but not significantly ( P >.05). Conclusions Monovision correction by LASIK improved functional near vision in presbyopic patients. Although visual acuity was good for far vision, contrast sensitivity and stereoacuity diminished significantly. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Visual quality after monovision correction by laser in situ keratomileusis in presbyopic patients

Purpose To use a double-pass system to compare the optical quality after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for mild to moderate myopia. Setting Universitat Politecnica de Catalunya, Terrassa, Barcelona Institute of Ocular Microsurgery, Barcelona, Spain. Design Comparative case series. Methods Optical quality was assessed with a clinical double-pass system preoperatively and 3 months after PRK or LASIK. The modulation transfer function (MTF), retinal image quality parameters (MTF cutoff frequency, Strehl ratio), and intraocular scattering (objective scatter index [OSI]) were calculated. Results This study evaluated 34 eyes that had PRK and 55 eyes that had LASIK. Both PRK and LASIK had a statistically significant impact on retinal image quality, although no significant differences between the techniques were observed. The MTF at 30 cycles per degree decreased by a factor of 1.50 in the PRK group and by a factor of 1.32 in the LASIK group. The MTF cutoff frequency decreased by a factor of 1.04 in the PRK group and by a factor of 1.06 in the LASIK group. The Strehl ratio decreased by a factor of 1.10 and 1.07, respectively. Photorefractive keratectomy and LASIK increased the objective scatter index by factors of 1.48 and 1.57, respectively. Significant correlations between the preoperative refraction and the OSI were found. Conclusions Retinal image quality was similarly reduced with PRK and LASIK, with no significant differences between the 2 methods. Some PRK patients had a residual refractive error that might have been related to corneal-wound healing still present 3 months postoperatively. Financial Disclosure Dr. Arjona is an investor in and Drs. Guell and Pujol are investors in and consultants to Visiometrics S.L., Terrassa, Spain. None of the other authors has a financial or proprietary interest in any material or method mentioned.

Optical quality after myopic photorefractive keratectomy and laser in situ keratomileusis: comparison using a double-pass system.

PURPOSE To investigate objective optical quality and changes in light scatter after femtosecond laser small incision lenticule extraction (SMILE) for moderate to high myopia correction. METHODS Prospective clinical study of 66 eyes of 66 patients (23 males, 43 females) with a mean age of 28.67 ± 6.62 years, mean spherical refraction of -6.06 ± 1.57 diopters, and mean cylindrical refraction of -0.68 ± 0.46 diopters. Every patient had a 3-month follow-up after a standard SMILE procedure. An optical quality analysis system was used to measure modulation transfer function cutoff frequency (MTFcutoff), Strehl2D ratio, and objective scatter index (OSI). RESULTS At 3 months postoperatively, mean spherical equivalent was 0.03 ± 0.24 diopters and corrected distance visual acuities of all patients were equal to or better than preoperative values, with a mean safety index of 1.12 ± 0.17 (range: 0.80 to 1.50) and mean efficacy index of 1.18 ± 0.21 (range: 0.80 to 1.50). Mean OSI increased from 0.75 preoperatively to 1.09 at 20 days postoperatively (P .05). MTFcutoff and Strehl2D ratio did not change significantly compared with preoperative values (P > .05). Multiple linear regression analysis revealed that preoperative OSI was significantly correlated with optical quality at 3 months. Patients with less preoperative OSI tended to acquire higher MTFcutoff (b = -8.61) and lower OSI (b = 0.65) (P < .05). CONCLUSIONS SMILE had little impact on retinal image quality after myopia correction. Postoperative OSI showed a temporary increase and then returned to normal.

Optical quality and intraocular scattering after femtosecond laser small incision lenticule extraction.

Purpose To evaluate the repeatability of measurements with a double-pass system. Setting Rothschild Foundation, Paris, France. Methods Eyes were separated into 2 control groups ( 40 years), a post-refractive surgery group, and a cataract group. Measurements were performed using the Optical Quality Analysis System. The main outcome measures were the objective scattering index (OSI), the cutoff frequency of the modulation transfer function (MTF), and the Strehl ratio. The repeatability limit was obtained from the individual standard deviations. Results Forty-two eyes were evaluated. The mean OSI value was 0.47 ± 0.11 (SD) in the younger control group, 1.73 ± 0.26 in the older control group, 1.34 ± 0.16 in the post-refractive surgery group, and 6.15 ± 0.50 in the cataract group. The mean cutoff MTF value was 39.44 ± 3.93 cycles per degree (cpd), 26.07 ± 3.89 cpd, 28.34 ± 2.84 cpd, and 13.3 ± 1.69 cpd, respectively, and the mean Strehl ratio, 0.234 ± 0.023, 0.146 ± 0.021, 0.169 ± 0.023, and 0.098 ± 0.010, respectively. The repeatability limit for the whole population was 0.841 (33.5%) for the OSI, 8.499 (31.1%) for the cutoff MTF, and 0.051 (31%) for the Strehl ratio. Conclusions The repeatability limit was good and equivalent for the OSI, the MTF, and the Strehl ratio values. There was a wide interval between the normal and pathologic threshold for OSI measurements, indicating that the reliability of the double-pass device complies with the requirements for quantitative assessment of scattering. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

/pdf/repeatability-of-measurements-with-a-double-pass-system-4e18rbdu6z.pdf

Repeatability of measurements with a double-pass system

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Marc Saab

Author Tools

Chat about Author

Papers

Repeatability of measurements with a double-pass system