Tjtp Van Den Berg
Netherlands Institute for Neuroscience
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Tjtp Van Den Berg.
Acta Ophthalmologica | 2012
Mcj Van Bree; Li Van Den Born; Tjtp Van Den Berg
Purpose The importance of straylight derives from the fact that it reduces retinal sensitivity. This may be particularly relevant in conditions with retinal dysfunction, such as Retinitis Pigmentosa (RP). Moreover in RP often early in life PSC cataract develops. The question of this study is whether straylight substantially contributes to visual disability in RP patients, potentially aggravated due to the combination of retinal degradation and increased straylight from cataract formation. In addition, straylight was used to predict possible benefit of (early) cataract surgery. Methods Twenty-five RP patients scheduled for cataract extraction (CE) participated. Before and after CE, best corrected visual acuity (BCVA) in logMAR, contrast sensitivity (CS) in log(CS), temporal contrast sensitivity (TCS) in log(TCS), and straylight (log of the straylight parameter s, log[s]) were tested. TCS, or flicker sensitivity, was tested with a new test, using the C-Quant hardware. TCS measurement was performed to assess foveal function isolated from the eye’s optical quality. Results Average pre CE log(s) value was 1.72, corresponding to a factor 6 straylight increase as compared to a healthy, young eye. Functionally significant improvement defined as >0.2 log, was only found for log(s). Only log(s) improvement was related to pre CE values. LogMAR and log(TCS) were correlated (pre CE r(19)= .57, p< .01; post CE ρ(19)= .47, p< .05). Pre and post CE log(TCS) values were similar (p= .14). Conclusion Straylight effects of cataract may substantially aggravate visual disability in RP patients, whereas BCVA may (not yet) be affected. Loss of BCVA may reflect foveal function rather than cataract. For proper CE referral straylight must be assessed.Purpose The importance of straylight derives from the fact that it reduces retinal sensitivity. This may be particularly relevant in conditions with retinal dysfunction, such as Retinitis Pigmentosa (RP). Moreover in RP often early in life PSC cataract develops. The question of this study is whether straylight substantially contributes to visual disability in RP patients, potentially aggravated due to the combination of retinal degradation and increased straylight from cataract formation. In addition, straylight was used to predict possible benefit of (early) cataract surgery.
Acta Ophthalmologica | 2012
Tjtp Van Den Berg
Purpose Straylight exerts its deleterious effect on visual function by reducing the sensitivity of the retina for whatever visual task the retina must perform: face recognition, movement detection, color discrimination etc. It can be expected that patients suffering from a retinal condition will be handicapped by straylight twice as much. To assess retinal condition in a non-confounded way, flicker sensitivity has been proposed. Such a test was developed on the C-Quant. Moreover, the test serves to assess whether a paptient has sufficient flicker sensitivity for the normal straylight test itself. Methods Visual field lay-out was identical, as well as the subjects 2AFC task, but the peripheral annulus was silent, as well as one of the two half fields in the center. The other half flield flickered at 8 Hz, with modulation depth according an adaptive staircase procedure. Outcome measure is logTCS (temporal contrast sensitivity). An uncertainty parameter (Unc) was included. Population test was performed in science fair settings on 400 subjects. Moreover in the laboratory 2 subjects were extensively tested to check whether optical defects, mimicked with trial lenses and scatter filters, affected the TCS outcome. Results Repeated measures standard deviation was 0.11 log units for the reference group using as reliability criterion unc<0.15. Normal values for logTCS were around 2 (threshold 1%) with some dependence on age (range 6-85 years). Test outcome did not change upon a ten-fold (optical) deterioration in visual acuity or straylight. Conclusion The test has adequate sensitivity to check a subjects capability to perform straylight assessment. The unc reliability criterion secures sufficient precision, also for assessment of retinal sensitivity loss. Commercial interestPurpose Straylight exerts its deleterious effect on visual function by reducing the sensitivity of the retina for whatever visual task the retina must perform: face recognition, movement detection, color discrimination etc. It can be expected that patients suffering from a retinal condition will be handicapped by straylight twice as much. To assess retinal condition in a non‐confounded way, flicker sensitivity has been proposed. Such a test was developed on the C‐Quant. Moreover, the test serves to assess whether a paptient has sufficient flicker sensitivity for the normal straylight test itself.
Acta Ophthalmologica | 2012
Tjtp Van Den Berg
Purpose A widely accepted validation criterion for cataract surgery is the likelihood that the surgery will be beneficial to the patient. Yet important variation exists between individual ophthalmologists in what constitute criteria for cataract surgery, and optometrists vary widely in their referral criteria. As a consequence huge differences in the amount of cataracts being treated exists between different centres. Some degree of standardisation is wanted. Visual acuity is considered, but predictability of surgical outcome is often difficult because visual acuity is confounded by the retinal condition. Straylight on the other hand is independent of retinal condition, and constitutes a complementary measure of quality of vision, complementary to visual acuity, corresponding to complaints such as glare, hazy vision, face recognition problems.
Acta Ophthalmologica | 2011
Tjtp Van Den Berg
Purpose Straylight is an important source of patient complaints. They can be voiced like halos, glare, hazy vision and blinding at night. With visual acuity, contrast sensitivity and slit lamp examination little may be found. Yet increased large angle light scattering in the eye media not detected by common tests, may degrade the image projected on the retina, thus decreasing the quality of vision. Aging changes to the crystalline lens and cataract are the most common causes of increased straylight, but many corneal conditions including laser treatment have been reported to increase straylight as well.Purpose Straylight is an important source of patient complaints. They can be voiced like halos, glare, hazy vision and blinding at night. With visual acuity, contrast sensitivity and slit lamp examination little may be found. Yet increased large angle light scattering in the eye media not detected by common tests, may degrade the image projected on the retina, thus decreasing the quality of vision. Aging changes to the crystalline lens and cataract are the most common causes of increased straylight, but many corneal conditions including laser treatment have been reported to increase straylight as well. Methods In order to evaluate the importance of straylight for clinical decision making, the quantity in which straylight is expressed must attain a meaningful value. Straylight is expressed logarithmically, as the logarithm of the straylight parameter s, which directly relates straylight to the (outer skirt) of the functional point-spread-function: s = θ^2 PSF. It was found earlier that expressed this way, the straylight value has functionally about equal importance as logMAR. The functional value of straylight was further corroborated by Aspinal et al., finding that straylight was the better predictor of clinical decisions on cataract surgery, as compared to visual acuity. Results Implications for the clinician include a shift in targeting of patient care. On the basis of straylight elevation treatment can be offered in cases where visual acuity is good. In the case of optical malfunction of the eye, as simple model for functional severity of the condition, the linear average of visual acuity in logMAR and straylight in log(s) is proposed. Data from population study on >5000 eyes show significant retargeting of cataract surgery. Conclusion Straylight retargets patient care. Commercial interest
Acta Ophthalmologica | 2011
Tjtp Van Den Berg
Purpose In this presentation an overview will be given on the basic optical effects connected with the tear film. A prominent role of the tear film is to create a smooth surface for the most powerful refractive interface of the eye, i.e. the air-cornea interface. On the other hand, the tear film itself can disturb proper imaging if light is scattered in it, or if its surface is not perfectly smooth. Methods Surface effects on optical image formation can be described with aberrometry. Only, in the case of the epithelial surface, present aberrometers do not have sufficient resolution to describe the fine irregularities. The group of Thibos designed a way to address this problem using the shape of the spot images of the Shack-Hartmann aberrometer. Effects of light scattering can be assessed using straylight measurement (implemented in the C-Quant from Oculus). Results Both aberrometric and straylight outcomes combine to form the ocular point-spread-function defining the functional problem originating from optical defects in the tear film. The aberrometric errors dominate the central part of the PSF, and thus visual acuity. Straylight corresponds to the peripheral part of the PSF, and dominates in complaints like glare and hazy vision. Literature models for both aspects of the optical problems in the eye media were used to delineate their effects on the PSF. Conclusion Two domains must be differentiated: the aberration domain and the small particle scatter domain, with corresponding parts (small angle vs large angle) to the PSF. Straylight typically originates ffrom small particles, as opposed to aberrations originating from refractile humps and bumps extending over large distances (tear film surface) or small small distances (epithelial surface). Commercial interestPurpose In this presentation an overview will be given on the basic optical effects connected with the tear film. A prominent role of the tear film is to create a smooth surface for the most powerful refractive interface of the eye, i.e. the air‐cornea interface. On the other hand, the tear film itself can disturb proper imaging if light is scattered in it, or if its surface is not perfectly smooth.
Acta Ophthalmologica | 2010
Tjtp Van Den Berg; Ije Van Der Meulen
Purpose Straylight is considered an important source of patient complaints. They can be voiced like halos, glare, hazy vision and blinding at night. With visual acuity, contrast sensitivity and slit lamp examination little may be found. Yet increased large angle light scattering in the eye media not detected by common tests, may degrade the image projected on the retina, thus decreasing the quality of vision. Aging changes to the crystalline lens and cataract are the most common causes of increased straylight. This study aimed to quantify the importance of straylight for daily life on the basis of patient complaint scores.Purpose Straylight is considered an important source of patient complaints. They can be voiced like halos, glare, hazy vision and blinding at night. With visual acuity, contrast sensitivity and slit lamp examination little may be found. Yet increased large angle light scattering in the eye media not detected by common tests, may degrade the image projected on the retina, thus decreasing the quality of vision. Aging changes to the crystalline lens and cataract are the most common causes of increased straylight. This study aimed to quantify the importance of straylight for daily life on the basis of patient complaint scores. Methods In a duocenter setting questionnaires were administered before and after cataract surgery. The 37 questions VFQ as well as a self developed 5 question straylight questionnaire were used. A comparison was made between the importance of visual acuity and of straylight to explain the questionnaire outcomes. Results A total of 214 patients were included in the study. For the comparison correlation coefficients were calculated between a weighted average of the 2 functional measures visual acuity and straylight on the one hand, and the questionnaire outcomes on the other. In all 4 cases (2 questionnaires x 2 visits) correlation was lowest for both visual acuity and straylight used in isolation. When visual acuity and straylight were combined to one combined score, correlation improved. Maximum correlation was found when visual acuity and straylight were combined 1:1 (preop) to 2:1 (postop), for both questionnaires. Conclusion For cataract patients, straylight is of about equal importance compared to visual acuity for their appreciation of daily function. In this comparison both were quantified as logarithms (logMAR and log(s)).
Acta Ophthalmologica | 2010
Tjtp Van Den Berg; Mcj Van Bree
Purpose Opacification of the posterior capsule (PCO) is known to degrade visual function on both counts: small angle resolution (visual acuity and contrast sensitivity) as well as large angle light scatter (straylight). No studies have been performed to delineate the optical characteristics of PCO as a basis for explanation of these visual function defects.
Acta Ophthalmologica | 2008
Rmma Nuijts; Luuk Franssen; Ne De Vries; Kf Tjia; Tjtp Van Den Berg
Purpose To measure levels of intraocular straylight following cataract surgery and implantation of either the ReSTOR SA60D3 IOL or the SA60AT monofocal IOL. Methods A newly developed straylight meter was used to objectively measure straylight in a prospective open observational case series at 6 months postoperatively in 66 eyes with the diffractive ReSTOR SA60D3 IOL (Alcon Laboratories) and in a control group of 40 eyes with the monofocal SA60AT IOL. A comparison with straylight levels in an age-matched population without cataract was performed. Results The straylight levels in the ReSTOR SA60D3 IOL and in the control group with the monofocal SA60AT IOL were 1.20±0.16 logunits and 1.10±0.19 logunits. When the difference in mean level of straylight was adjusted for age by multivariate analysis of the combined pseudophakic groups, mean straylight levels were 0.078 logunits lower for the monofocal SA60AT IOL group as compared to the multifocal ReSTOR SA60D3 IOL group (p=0.026). Straylight levels in both pseudophakic groups were lower than those of the normal age-matched control group without cataract (p<0.0001). Conclusion Levels of intraocular straylight log(s) were significantly lower (p<0.0001) for both types of IOL as compared to age-matched subjects from the normal population, with expected reduction of complaints of glare and halos and higher levels of contrast sensitivity.The mean level of intraocular straylight 6 months postoperatively was higher for subjects with a ReSTOR SA60D3 IOL as compared to subjects with a monofocal SA60AT IOL, with expected less gain in contrast sensitivity and less reduction of glare and halo complaints.
Acta Ophthalmologica | 2008
Tjtp Van Den Berg
Acta Ophthalmologica | 2013
Tjtp Van Den Berg