AIMS: Visual acuity determination is an important task in ophthalmology and optometry practices. Visual acuity can be examined objectively or subjectively. The objective examination method, sVEP, allows for quick objective measurements of patient's visual acuity. Previous studies have not demonstrated the repeatability of this objective sVEP method. This study aims to evaluate the sVEP method and compare it to a subjective method. METHODS AND RESULTS: The sample was divided into two groups. For the first group, visual acuity was measured with sVEP and Snellen methods on only one patient twelve times. In the second group, visual acuity was measured twice with sVEP followed twice with the Snellen method with Landolt's rings and logMAR modification on 32 non-pathological patients. Results showed significant differences between average values of visual acuity obtained with both methods (sVEP and Snellen) in both samples (T-test, P < 0.01; Wilcoxon test, P = 0.02 in second group). In the second group, significant correlations between repeated sVEP measurements (Spearman test, P < 0.05, r = 0.69) were found but no significant correlation between average sVEP measurement and average Snellen measurement (Spearman test, P > 0.05, r = 0.15) was found. CONCLUSION: Objective measurement of visual acuity with sVEP is a valid and reliable method, but is recommended only when it is not possible to use a subjective method for measuring visual acuity, e.g. children, patients with mental retardation or simulating/dissimulating patients.

• Klíčová slova
• ETDRS chart, Snellen chart, electrophysiological methods, visual acuity, visual evoked potentials,
• MeSH
• dospělí MeSH
• elektrody MeSH
• lidé MeSH
• mladý dospělý MeSH
• osvětlení MeSH
• zraková ostrost fyziologie   MeSH
• zrakové evokované potenciály fyziologie   MeSH
• zrakové testy metody   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

PURPOSE: The decrease in visual acuity under low luminance conditions is well known. Recent laboratory evidence showed that crowding under low luminance (mesopic) light levels is less robust than under photopic conditions. The present study examines whether such differences in crowding influence clinical measurements of mesopic visual acuity, including test-retest repeatability. METHODS: Twenty adult subjects with normal or corrected to normal visual acuity were recruited for the study. Monocular visual acuity was measured under photopic (228 cd/m2) and mesopic (0.164 cd/m2) luminance conditions using a letter chart, similar in principle to the ETDRS logMAR chart, presented on a computer monitor. Three rows of five letters, each row differing in size by 0.05 logMAR from largest to smallest were displayed at the center of the monitor. The level of crowding was varied by varying the separation between horizontally adjacent letters from 100% optotype size to 50, 20, and 10% optotype size. Inter-row spacing was proportional to optotype size. Observers read the letters on the middle row only. Measurements continued by reducing the size of the letters, until three or more errors on the middle row were made. Each correctly identified letter contributed 0.01 to the recorded logMAR score. All measurements were repeated for each subject on two separate days. RESULTS: Visual acuity (logMAR) was significantly better under photopic than mesopic luminance conditions with a mean difference of 0.48 logMAR. Visual acuity also decreased with decreasing letter separation (i.e. increase in crowding). However, the decrease in visual acuity for the smallest letter separation was less under the mesopic luminance condition, even after accounting for the increased size of threshold acuity letters. Test-retest repeatability for mesopic and photopic conditions was not significantly different. CONCLUSIONS: Crowding under mesopic luminance conditions has less impact on visual acuity than under photopic luminance.

• Klíčová slova
• Crowding, Luminance, Mesopic, Photopic, Visual acuity, logMAR,
• MeSH
• citlivost na kontrast MeSH
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• referenční hodnoty MeSH
• světelná stimulace MeSH
• vidění barevné fyziologie   MeSH
• vidění mezopické fyziologie   MeSH
• zraková ostrost * MeSH
• zrakové testy metody   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

PURPOSE: The aim of this study was to develop a simple and reliable method for the objective assessment of visual acuity by optimizing the stimulus used in commercially available systems and by improving the methods of evaluation using a nonlinear function, the modified Ricker model. METHODS: Subjective visual acuity in the normal subjects was measured with Snellen targets, best-corrected, and in some cases also uncorrected and with plus lenses (+ 1 D, + 2 D, + 3 D). In patients, subjective visual acuity was measured best-corrected using the Freiburg Visual Acuity Test. Sweep VEP recordings to 11 spatial frequencies, with check sizes in logarithmically equidistant steps (0.6, 0.9, 1.4, 2.1, 3.3, 4.9, 7.3, 10.4, 18.2, 24.4, and 36.5 cpd), were obtained from 56 healthy subjects aged between 17 and 69 years (mean 42.5 ± 15.3 SD years) and 20 patients with diseases of the lens (n = 6), retina (n = 8) or optic nerve (n = 6). The results were fit by a multiple linear regression (2nd-order polynomial) or a nonlinear regression (modified Ricker model) and parameters compared (limiting spatial frequency (sflimiting) and the spatial frequency of the vertex (sfvertex) of the parabola for the 2nd-order polynomial fitting, and the maximal spatial frequency (sfmax), and the spatial frequency where the amplitude is 2 dB higher than the level of noise (sfthreshold) for the modified Ricker model. RESULTS: Recording with 11 spatial frequencies allows a more accurate determination of acuities above 1.0 logMAR. Tuning curves fitted to the results show that compared to the normal 2nd-order polynomial analysis, the modified Ricker model is able to describe closely the amplitudes of the sweep VEP in relation to the spatial frequencies of the presented checkerboards. In patients with a visual acuity better than about 0.5 (decimal), the predicted acuities based on the different parameters show a good match of the predicted visual acuities based on the models established in healthy volunteers to the subjective visual acuities. However, for lower visual acuities, both models tend to overestimate the visual acuity (up to ~ 0.4 logMAR), especially in patients suffering from AMD. CONCLUSIONS: Both models, the 2nd-order polynomial and the modified Ricker model performed equally well in the prediction of the visual acuity based on the amplitudes recorded using the sweep VEP. However, the modified Ricker model does not require the exclusion of data points from the fit, as necessary when fitting the 2nd-order polynomial model making it more reliable and robust against outliers, and, in addition, provides a measure for the noise of the recorded results.

• Klíčová slova
• Sweep VEP, Visual acuity, Visual electrophysiology, Visual evoked potentials,
• MeSH
• dospělí MeSH
• elektroretinografie MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• nemoci oční čočky patofyziologie   MeSH
• nemoci retiny patofyziologie   MeSH
• nemoci zrakového nervu patofyziologie   MeSH
• senioři MeSH
• statistické modely MeSH
• zdraví dobrovolníci pro lékařské studie MeSH
• zraková ostrost fyziologie   MeSH
• zrakové evokované potenciály fyziologie   MeSH
• zrakové testy metody   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The adverse impact of adjacent contours on letter visual acuity is known as crowding but there is conflicting evidence that foveal crowding may be reduced or disappears under low contrast conditions. Potential differences in foveal crowding with contrast on clinical measurements of visual acuity, including test-retest repeatability, were assessed. Visual acuity was measured at the fovea on adult participants with normal vision under three different contrast levels (- 90, - 10 and - 5%). Three rows of 5 letters, each row differing in size by 0.05 logarithm of the minimum angle of resolution (logMAR) from largest to smallest were displayed at the center of a monitor. Crowding was varied by varying the separation between horizontally adjacent letters from 100% optotype size to 50%, 20% and 10% optotype size. Inter-row spacing was proportional to optotype size. Observers read the letters on the middle row only. Measurements continued by reducing the size of the letters until 3 or more errors were made and were repeated on two separate days. Visual acuity worsened as both letter contrast decreased and inter-optotype separation reduced (expressed as a percentage of letter width). When expressed in minutes of arc of separation the impact of crowding was the same across all contrasts. Crowding occurs for both high and low contrast charts and should be considered when assessing low contrast visual acuity. Test-retest repeatability showed little or no dependence on either contrast or inter-optotype separation.

• MeSH
• dospělí MeSH
• fovea centralis * MeSH
• lidé MeSH
• zraková ostrost MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

PURPOSE: To screen visual acuity in two refugee camps in Greece and explore the feasibility of replicating these methods on a nationwide scale. METHODS: Visual acuity was assessed in all participants using web-based Democritus Digital Acuity & Reading Test (DDART). Furthermore, the immigrants responded to a structured questionnaire regarding their demographics and medical history. RESULTS: A total of 330 adult refugees and immigrants were recruited. A total of 47.3% of the patients had never undergone ophthalmological examination. A significant negative correlation was detected between age (r = -0.207, p < 0.001) and educational background (r = -0.135, p = 0.014), suggesting that younger immigrants who had attended compulsory education were more likely to have their eyes checked in their home country. A total of 6.97% of patients presented with impaired vision and were referred for further care. All remote DDART measurements presented no differences from the corresponding hospital-based data in the referred cases. CONCLUSIONS: Visual acuity screening using DDART provides valuable information regarding the visual capacity of refugees. The study outcomes suggest that pilot methods can be replicated on a nationwide scale. CLINICAL TRIALS: Gov number NCT05209581; date of registration: January 13, 2022. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. The authors have no funding or conflicts of interest to disclose. Patients Consent Statement: The patients sign written consent form.

• Klíčová slova
• DDART, immigrants, refugees, screening, visual acuity,
• MeSH
• dospělí MeSH
• emigranti a imigranti * MeSH
• internet MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• pilotní projekty MeSH
• průzkumy a dotazníky MeSH
• screening zrakových vad metody   MeSH
• senioři MeSH
• uprchlíci * MeSH
• zraková ostrost * MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• pozorovací studie MeSH
• Geografické názvy
• Řecko MeSH

The statistical evaluation of the visual acuity has to be based on the non-parametric test as the decimal scale of the visual acuity forms a serial scale and not the intervallic one. From the theoretic point of view, the most advantageous approach uses the paremetric statistical tests. Visual acuity is measured on optotypic tables with log gradiation of the optotype size. At present time optotypes of this kind are not available in Czechoslovakia.

• MeSH
• lidé MeSH
• statistika jako téma MeSH
• zraková ostrost * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH

1) The ordinary Snellen chart with letter optotypes is not suited for research purposes. Unequal legibility of letters, unequal number of optotypes on rows of the chart and unequal progression of letter sizes limit the usage of such charts for screening purposes only. 2) The results of our computerised method for determining of visual acuity correlate very well with the results gained using the standardised Landolt optotype chart (r = 0.931). Our method brings whole line acuity, threshold visual acuity with its variability and a new parameter of line slope (decrease of correct readings from 95% to 5%), expressed in standardised rows (log MAR = 0.1). The results are printed on a simple printer and stored in a database.

• MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• počítače MeSH
• senioři MeSH
• zraková ostrost * MeSH
• zrakové testy metody   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH

PURPOSE: To compare effect of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) on contrast sensitivity (CS) and best corrected visual acuity (BCVA) in high myopia. METHODS: 38 myopes (PRK) and 31 patients (LASIK) were examined before and 1, 3, 6, and 12 months postoperatively. Mean preoperative spherical equivalent was -8.0 +/- 1.7D (PRK) and -9.2 +/- 2.1D (LASIK). CS was tested on a computerized system of the Contrast Sensitivity 8010 Type at 6 spatial frequencies (0.74 and 29.55 c/deg), BCVA was measured on logMAR charts. RESULTS: At 12 months postoperatively, mean spherical equivalent was -0.6 +/- 1.0D (PRK) and -1.0 +/- 0.8D (LASIK). Postoperative values of CS were significantly higher in the PRK group, except for spatial frequencies of 3.69 and 7.39 c/deg up to 3 months postoperatively. The initial significant decrease of BCVA lasted up to 6 months after PRK. In the LASIK group BCVA was not significantly different from its preoperative level at the 3-months follow-up. CONCLUSIONS: The significant improvement of CS after PRK suggest that PRK can improve quality of vision in eyes with high myopia. Although recovery of BCVA after LASIK was faster than after PRK, there may be a persistent decrease in CS.

• MeSH
• citlivost na kontrast MeSH
• fotorefrakční keratektomie * MeSH
• laserová modelace rohovky pod rohovkovou lamelou * MeSH
• lasery excimerové MeSH
• lidé MeSH
• myopie patofyziologie   chirurgie   MeSH
• refrakce oka MeSH
• zraková ostrost MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

• MeSH
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• zraková ostrost * MeSH
• zrakové testy přístrojové vybavení   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH

BACKGROUND: Central serous chorioretinopathy (CSC) is characterised by a serous detachment of the neurosensory retina in the macula. Chronic CSC tends to affect older individuals with a less favourable visual outcome. Photodynamic therapy (PDT) with verteporfin is a possible therapeutic approach in cases of CSC with no tendency for spontaneous resorption. PDT has shown good anatomic and functional results in treating chronic CSC. For the purpose of diminishing side effects, modifications of the standard protocol were used. MATERIALS AND METHODS: This is a retrospective study of 32 eyes with CSC of 32 patients treated by half-fluence PDT. The patients underwent complete ophthalmology examination. On optical coherence tomography (OCT) we measured central retinal thickness (CRT), the outer nuclear layer (ONL), presence of subfoveolar detachment of retinal pigment epithelium (PED), disturbance of external limiting membrane (ELM), morphological changes in the inner segment/outer segment (IS/OS) line and retinal pigment epithelium (RPE) atrophy. We evaluated at baseline, 3 and 12 months after PDT. RESULTS: The mean BCVA at baseline was 0.41 ± 0.23 log MAR, the mean BCVA at 3 months was 0.24 ± 0.20 and at the end of the follow-up it was 0.23 ± 0.200. We observed statistically significant improvements of visual acuity after 3 and 12 months (p < 0.001, Wilcoxon test). The mean central retinal thickness at baseline was 373 ± 87 µm, the mean CRT after 3 months was 234 ± 42 µm and after 12 months 223 ± 39 µm. A significant reduction from baseline was seen after 3 months and 12 months (p < 0.001, Wilcoxon test). Baseline ONL reached 80 ± 27 µm, after 3 months it was 78 ± 20 and after 12 months it was 74 ± 20 µm. We observed a statistically significant change in diminishing the amount of PED after PDT after 3 months and after 12 months (p = 0.021, McNemar's test). We observed that in patients with RPE ablation, there is lower chance for the restitution of the IS/OS layer (p = 0.045, Mann-Whitney test). We observed a negative association between the improvement of visual acuity after 12 months and the presence of RPE ablation (p = 0.031, Mann-Whitney test). Restitution of ELM was significantly more often in patients with shorter duration of symptoms, (p = 0.027 after 3 months, p = 0.033 after 12 months after PDT, Spearman correlation). Neither ocular nor systemic adverse effects were observed during the follow-up period. CONCLUSIONS: Half-fluence PDT treatment has shown to be a usually safe and often effective therapy in patients with chronic CSC. This study suggests that the most important predictive factor is baseline visual acuity. The important anatomical change detected using OCT is a thinning of the outer nuclear layer. Nonetheless, other studies with a larger number of patients and a longer follow-up are required.

• Klíčová slova
• Central serous chorioretinopathy, chronic, morphological changes, optical coherence tomography, photodynamic therapy,
• MeSH
• centrální serózní chorioretinopatie diagnóza   farmakoterapie   patofyziologie   MeSH
• chronická nemoc MeSH
• dospělí MeSH
• fluoresceinová angiografie MeSH
• fotochemoterapie metody   MeSH
• fotosenzibilizující látky terapeutické užití   MeSH
• fundus oculi MeSH
• lidé středního věku MeSH
• lidé MeSH
• následné studie MeSH
• optická koherentní tomografie MeSH
• porfyriny terapeutické užití   MeSH
• retinální pigmentový epitel patologie   MeSH
• retrospektivní studie MeSH
• senioři MeSH
• verteporfin MeSH
• výsledek terapie MeSH
• zraková ostrost * MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fotosenzibilizující látky MeSH
• porfyriny MeSH
• verteporfin MeSH