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- Nilsson, M, et al.
(författare)
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Perception of very small visual stimuli in the fovea : normative data for the Rarebit Foveal Test.
- 2006
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Ingår i: Clinical and experimental optometry. - : Informa UK Limited. - 0816-4622 .- 1444-0938. ; 89:2, s. 81-85
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Conventional visual tests are not sensitive enough to detect low degree neural damage, as 6/6 (1.0) visual acuity can be upheld with less than two-thirds of the normal number of optic nerve axons. The aim of the current study was to evaluate the physiologic properties of a new computerised test, the Rarebit Fovea Test (RFT), using very small stimuli, by quantifying the effect of age and binocular summation in relation to stimulus luminance. METHODS: The RFT relies on the perception of very small (less than 0.5 minutes of arc) bright stimuli. Two different experiments were performed. 1. Thirty-five subjects (age 19 to 63 years) were tested with five different stimulus luminances, 158, 64, 53, 41 and 33 cd/m(2). 2. Nineteen subjects (age 19 to 63 years) were tested using binocular stimulation to define the binocular summation. RESULTS: Significantly reduced median hit rates were observed at luminances of 53 cd/m(2) or below. Age and mean hit rate correlated negatively at all luminance levels below 158 cd/m(2). The mean hit rate from binocular stimulation, compared to the highest value from monocular stimulation in the same subject, was increased by a factor of 1.54 +/- 0.45 (SD). No age effect was found regarding binocular summation. CONCLUSIONS: The results in the current study indicate that RFT can identify some of the well-known features of the visual system, that is, the effects of age and binocular summation, provided that the stimulus luminance is adequately selected.
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| 4. |
- Martin, Lene, 1953-, et al.
(författare)
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Test-retest variation in macular thickness measurements with the Heidelberg Retina Tomograph
- 2012
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Ingår i: Clinical and experimental optometry. - : Informa UK Limited. - 0816-4622 .- 1444-0938. ; 95:5, s. 515-521
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The aim was to evaluate the test-retest variation of macular thickness measurements using the Heidelberg Retina Tomograph (HRT3) Retina Module and compare it with the Stratus optical coherence tomography (OCT). As no normative data has been published for the HRT Retina Module, a secondary purpose was to obtain reference values for this technique. Methods: Thirty healthy subjects and nine patients with macular oedema were examined. The healthy subjects underwent five examinations by two experienced examiners at two different occasions. The patients with maculopathy were examined twice by one examiner on one occasion. All measurements were made with both the HRT3 and the Stratus OCT and the macular thickness measurements were used for calculations of thetest-retest variation. Results: In healthy subjects the coefficient of variation (CV) ranged from 4.5 to 8.8 per cent with the HRT3 and from 0.6 to 1.5 per cent with the Stratus OCT. In the nine patients withmacular oedema, the HRT CV ranged from 7.9 to16.6 per cent and for OCT from 1.1 to 2.5 per cent. The intra-class correlation in the central area for intra-observer/intra-visit in healthy subjects was 0.78 with the HRT3 and 0.93 with the Stratus OCT. Corresponding values for the patients with macular oedema were 0.64 with the HRT3 and 1.0 with the Stratus OCT. Mean macular thickness was significantly larger in all areas measured with the HRT3 compared with the Stratus OCT. No significant correlations were found between the thickness values from the different instruments. Conclusion: In this study, macular thickness was measured with two different techniques. The HRT3 showed lower repeatability and reproducibility as well as a higher CV compared with the Stratus OCT in both healthy subjects and patients with macular oedema. This difference might be of clinical relevance, even though the nine patients with maculopathy in the current study showed abnormal results with both methods.
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| 5. |
- Nilsson, Maria M, et al.
(författare)
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Fixation stability during Rarebit Fovea Test
- 2009
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Ingår i: Clinical and experimental optometry. - : Informa UK Limited. - 0816-4622 .- 1444-0938. ; 92:1, s. 9-13
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Unstable fixation has been reported to be a common cause of unreliable results in perimetry. The Rarebit Fovea Test (RFT) is a computerised foveal function test that evaluates the 4 x 3 degrees central visual field, using very small test stimuli. To minimise the test time, no fixation control is used. Instead, stable fixation is facilitated by the use of a dynamic fixation target. The aim of the current study was to evaluate fixation stability during a RFT examination by continuous recording of the eye movements. METHOD: Twelve healthy subjects were enrolled in the study together with two amblyopic subjects. A three-dimensional eye tracker was used to measure eye movements during two test sessions. All subjects went through one session of fixation measurement with stimulus presentation and one session without stimulus presentation. Both sessions lasted approximately 90 seconds. RESULTS: Mean hit rate (MHR) in the whole group was 89.7 per cent. Five out of 14 subjects had abnormal RFT results. There was no significant difference in fixation stability either between the test sessions with and without stimulus presentations (p = 0.79) or between the subjects with abnormal (n = 5) and normal (n = 11) MHR, (p = 0.55). CONCLUSION: Fixation seems stable during RFT testing, thus the test design and fixation target used in the RFT could be considered adequate, at least in subjects with normal or near normal visual function. Further studies are needed to evaluate how different visual abnormalities will affect fixation stability during RFT testing.
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| 6. |
- Nilsson, Maria, et al.
(författare)
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Macular structure and function and the development of retinopathy in diabetes
- 2012
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Ingår i: Clinical and experimental optometry. - : Informa UK Limited. - 0816-4622 .- 1444-0938. ; 95:3, s. 306-310
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Tidskriftsartikel (refereegranskat)abstract
- Background: The aim of this study was to evaluate the relationship between structural and functional changes identified with the Rarebit fovea test (RFT) in diabetic patients over two years. In addition, we evaluated whether the RFT changes at baseline can predict vascular changes detectable by conventional screening methods four to six years later. Methods: Forty-two patients with diabetes and 42 age-matched healthy subjects underwent an initial examination. Two years later, 25 of the diabetic patients and 20 of the controls were re-examined in the same way. Four to six years later, 40 of the diabetic patients underwent a standard screening examination including fundus photography. After two years, all subjects were examined with the RFT and visual acuity (VA) was assessed. In addition, optical coherence tomography (OCT) and fundus photography were performed on the diabetic patients. At a screening examination of the diabetic patients after four to six years, fundus photographs were reviewed. Results: After two years, a marked difference in RFT results was observed between the 20 normal subjects and the 25 patients with diabetes. Results from other tests (VA and central retinal thickness, as measured with OCT) were unchanged compared with the initial examinations. Fundus photography four to six years later of 40 of the 42 diabetic patients showed an increased incidence of retinopathy unrelated to the RFT findings at baseline. Conclusions: The findings in the current study indicate that the RFT might detect macular dysfunction in diabetic eyes without microvascular changes. This dysfunction increased during a two-year period and presumably reflects neural impairment in diabetes mellitus but did not predict development of retinopathy during the four to six year period.
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| 8. |
- Scott, Rolene, et al.
(författare)
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A preliminary investigation into the direct measurement of intra-ocular light scatter after radial keratotomy
- 1991
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Ingår i: Clinical and experimental optometry. - : Wiley-Blackwell. - 0816-4622 .- 1444-0938. ; 74:6, s. 204-209
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Tidskriftsartikel (refereegranskat)abstract
- A glare score based on intra-ocular light scatter and a questionnaire-based subjective assessment of glare were determined for 18 patients who had undergone radial keratotomy (RK) two weeks to 27 months previously. Results were compared to those of 15 control subjects. T-tests showed no significant difference in glare experienced under photopic conditions by RK patients and control subjects. There was no systematic relationship between glare scores and the subjective assessment of glare, nor between glare scores or subjective assessment of glare and the time which had elapsed since surgery. However, a weak relationship (r2=0.36) was found between glare scores and absolute refractive error. It was concluded that RK did not produce significant levels of intra-ocular light scatter under photopic conditions (155 lux).
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| 10. |
- Benyahia Erdal, Nejla, et al.
(författare)
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In vitro and in vivo effects of ophthalmic solutions on silicone hydrogel bandage lens material Senofilcon A
- 2018
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Ingår i: Clinical and experimental optometry. - : WILEY. - 0816-4622 .- 1444-0938. ; 101:3, s. 354-362
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Tidskriftsartikel (refereegranskat)abstract
- Background: Acuvue Oasys silicone hydrogel contact lenses (Senofilcon A) are used as bandage lenses and often combined with ophthalmic solutions in the treatment of ocular diseases. Concerns have been raised regarding the compatibility and effect of eye-drop solutions on the bandage lenses, which have led to frequent replacement of lenses causing clinical problems. Some patients experience pain or discomfort during treatments and the accumulation of drugs and preservatives in lenses has been suggested as a possible reason. The aim with this study was to investigate the effect of ophthalmic solutions on silicone hydrogel bandage lens material Senofilcon A in vitro and in vivo. Methods: The effect of three common ophthalmic solutions Isopto-Maxidex, Timosan and Oftaquix on Acuvue Oasys (Senofilcon A) bandage lenses was evaluated. An in vitro model method was developed where drug and preservative uptake by Acuvue Oasys was monitored with ultraviolet-visible spectroscopy and laser desorption ionisation mass spectrometry. Surface morphology changes of the lenses were evaluated using scanning electron microscopy. The method was then implemented for the in vivo pilot study evaluating lenses worn by patients. Results: In vitro model study monitoring the drug and preservatives uptake showed that the active ingredients from all the eye drops together with preservatives were taken up by the lenses in significant amounts. For the in vivo study no traces of active ingredients or preservatives could be found on the worn and treated lenses regardless of time being worn or dosage profiles. The surface morphology changes in the in vivo study were also minor in contrast to the changes observed in the in vitro scanning electron microscopy images. Conclusion: The in vivo results demonstrate minor effects of the ophthalmic solutions on the worn lenses. These results do not support the building up of preservatives and drugs on the contact lenses as the cause of pain or discomfort experienced by some patients, which is encouraging for the use of bandage lenses in combination with ophthalmic solutions.
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