Rune Brautaset

Central and peripheral corneal thinning in keratoconus.

Purpose: Recent data regarding the mid-peripheral portion of the removed corneal button in transplant surgery indicate histopathologically that keratoconus was present also in the peripheral portion of the button. The intent of this study was therefore to investigate if peripheral changes could also be detected clinically by measuring the central and peripheral corneal thickness of KC patients. Methods: Corneal pachymetry was measured with the Visante optical coherence tomography and Orbscan II. Of 52 subjects, 26 were KC subjects and 26 were age- and sex-matched control subjects. Results: Corneal thickness, in KC patients, was significantly reduced in all areas compared with corneal thickness among controls with both the Visante optical coherence tomography and Orbscan II. Conclusion: The results of the present study have provided clinical evidence that KC is a disease affecting a wider area of the cornea. Although the KC cornea shows the greatest change in thickness in the ectatic region, this attenuation declines toward the periphery. The presence of peripheral thinning indicated that KC may be a “pancorneal” pathology and not limited to the ectatic portion.

Spherical aberration in contact lens wear

INTRODUCTION The aim of the present studies was to investigate the effect on spherical aberration of different non custom-made contact lenses, both with and without aberration control. METHODS A wavefront analyser (Zywave, Bausch & Lomb) was used to measure the aberrations in each subjects right eye uncorrected and with the different contact lenses. The first study evaluated residual spherical aberration with a standard lens (Focus Dailies Disposable, Ciba Vision) and with an aberration controlled contact lens (ACCL) (Definition AC, Optical Connection Inc.). The second study evaluated the residual spherical aberrations with a monthly disposable silicone hydrogel lens with aberration reduction (PureVision, Bausch & Lomb). RESULTS Uncorrected spherical aberration was positive for all pupil sizes in both studies. In the first study, residual spherical aberration was close to zero with the standard lens for all pupil sizes whereas the ACCL over-corrected spherical aberration. The results of the second study showed that the monthly disposable lens also over-corrected the aberration making it negative. The changes in aberration were statistically significant (p<0.05) with all lenses. CONCLUSION Since the amount of aberration varies individually we suggest that aberrations should be measured with lenses on the eye if the aim is to change spherical aberration in a certain direction.

Corneal and conjunctival epithelial staining in hydrogel contact lens wearers.

Objectives. The purpose of this study was to investigate the prevalence of conjunctival and corneal epithelial staining in soft contact lens wearers and to see if staining could be associated with factors such as type of lens worn, wearing time, care system, age, and sex. Methods. The records of 338 adapted hydrogel contact lens wearers were examined retrospectively. Results. Conjunctival staining was found to be present in 32.5% of the subjects and corneal staining was found to be present in 19.5% of subjects. None of the subjects had staining above grade 2 using the Cornea and Contact Lens Research Unit scale. Because of the low prevalence of staining, the low grading of staining found and the large variation in refractive power, lens type worn, wearing modality, and solution used statistical analysis for association between staining and different factors could only be performed for the association between sex and staining and between corneal and conjunctival staining. However, no statistical significant association could be demonstrated. Discussion. Despite the low prevalence of staining the conjunctiva and cornea should be examined carefully in contact lens wearers and prospective wearers because the conjunctival and corneal epithelium serve as protective barriers for the underlying layers of the cornea and conjunctiva. To allow comparison of data obtained in different studies assessing corneal staining, it is recommended that clinicians develop and adopt a universal standard protocol for this measure.

Accommodation Insufficiency in Children: Are Exercises Better than Reading Glasses?

Purpose: The aim of the present study was to investigate which mode of therapy, plus lens (+1.00D) reading addition (PLRA) or spherical flipper (± 1.50D), is the most effective in the treatment of accommodative insufficiency (AI). Methods: Initially, 24 subjects (mean age 10.3 years, ± 2.5 SD) with AI were included in the study. Ten subjects completed 8 weeks of PRLA treatment whereas 9, out of 14, subjects completed 8 weeks of spherical flipper treatment. Results: There was a statistically significant improvement in the accommodative amplitude with both regimes of treatment [F(1, 17) = 18.84, p = 0.0004). Spherical flipper treatment was found to have an overall larger effect on accommodative function as compared with PLRA treatment. However, accommodation did not reach normal values after only 8 weeks of treatment. Discussion: The results indicate that both methods improve the accommodative amplitude, but that overall accommodative function reaches higher levels of improvement with spherical flipper as compared with PLRA treatment. However, the accommodative function did not gain normal values in 8 weeks of treatment with either regime.

The influence of accommodative insufficiency on reading.

Background:  It is not known how accommodative insufficiency influences reading performance.

The posterior chamber phakic refractive lens (PRL): a review

Implantation of phakic intraocular lenses (pIOLs) is a reversible refractive procedure, preserving the patient’s accommodative function with minimal induction of higher order aberrations compared with corneal photoablative procedures. Despite this, as an intraocular procedure, it has potential risks such as cataracts, chronic uveitis, pupil ovalization, corneal endothelial cell loss, pigmentary dispersion syndrome, pupillary block glaucoma, astigmatism, or endophthalmitis. Currently, only two models of posterior chamber pIOLs are commercially available, the implantable collammer lens (STAAR Surgical Co.) and the phakic refractive lens (PRL; Zeiss Meditec). The number of published reports on the latter is very low, and some concerns still remain about its long-term safety. The present article reviews the published literature on the outcomes after PRL implantation in order to provide a general overview and evaluate its real potential as a surgical refractive option.

Evaluation of aspects of binocular vision in children with dyslexia.

Background: Prevalence of dyslexia is 5%–10% of the population. Opinions differ on how binocular function affects dyslexia. The aim of the present study was to evaluate the binocular function in dyslexic children and compare it with a group of age-matched control children. Methods: The study was performed at Ängkärrskolan and at Kungsholmen elementary schools in Stockholm, Sweden. Sixty-three children with dyslexia and 60 control children between fourth and ninth grade participated. Monocular and binocular visual acuity, refractive error, best corrected visual acuity at distance and near, near point of convergence, amplitude of accommodation, stereopsis, phorias, and fusional reserves were evaluated in all of the children. Results: The results show that there was no difference in the visual functions tested except for the amplitude of accommodation, which was found to be reduced both monocularly and binocularly in the dyslexic children. Conclusion: This study showed that only the amplitude of accommodation seems to differ in children with dyslexia as compared with the control children; however, the ability to accommodate was still good and is unlikely to hamper reading and learning ability. The results therefore support that the recent findings of binocular deficits in dyslexic children are a result of the phonological deficit of dyslexia and not an underlying cause of dyslexia.

Spherical aberration in relation to visual performance in contact lens wear

INTRODUCTION The aim of the present study was to evaluate changes in spherical aberration and their effect on visual quality (visual acuity and contrast sensitivity) in both distance and near with different non-custom-made contact lenses. METHODS A wavefront analyser was used to measure the aberrations in each subjects eyes uncorrected and with the contact lenses: a standard lens and two aspherical contact lenses. High-contrast visual acuity at distance was measured with Test-Chart 2000 (100% contrast) and at near with Sloan ETDRS Near Point chart (100% contrast). Low-contrast visual acuity at distance was measured with Test-Chart 2000 (10% contrast) and contrast measurements at near with Mars letter contrast sensitivity chart. RESULTS Mean spherical aberration was positive for all pupil sizes in the uncorrected eye, residual spherical aberration was close to zero with the standard lens for all pupil sizes, whereas the two aspheric contact lenses over-corrected spherical aberration. The changes in aberration were statistically significant (p < 0.05) with all lenses. No significant difference could be detected between trial frame correction, spherical and aspherical soft contact lens designs with respect to visual quality. This was the case for both distance and near. CONCLUSION The results are in line with previous studies and indicate that non-custom-made spherical aberration control contact lenses have little effect on visual quality as defined in this study.

Treatment of Accommodative Insufficiency with Plus Lens Reading Addition: is +1.00 D Better than +2.00 D?

Purpose: The aim of the present study was to evaluate if +2.00 D lens reading addition has the same effectiveness as +1.00 D reading addition in the treatment of accommodative insufficiency (AI). Methods: Initially 22 subjects (mean age 11.8 years, ±3.54 SD) with AI were included in the study. The treatment was given according to a randomization list; 11 subjects were given +1.00 D reading addition and the other 11 were given +2.00 D reading addition, for 8 weeks of treatment. The Visual Analogue Scale (VAS) was used to evaluate the subjective degree of asthenopia before and after treatment. Results: The results showed a statistical significant improvement of the accommodative amplitude with +1.00 D reading addition after 8 weeks of treatment. In the +2.00 D reading addition group the improvement of accommodative amplitude was not significant. The reduction in VAS score was significant in both groups. Discussion: The results indicate that +2.00 D reading addition does not exercise the accommodative system in the same amount as +1.00 D reading addition to improve the accommodative amplitude. We therefore recommend that +2.00 D reading addition is not used for treatment of AI.

Evaluation of Accommodative Insufficiency with the Visual Analogue Scale (VAS)

Purpose: The purpose of this study was to evaluate whether asthenopic symptoms in schoolchildren diagnosed with accommodative insufficiency (AI) and graded with the Visual Analogue Scale (VAS) could be correlated with the degree of accommodative deficiency in these children, and to investigate if VAS grading of the asthenopic symptoms could be used as an instrument to indicate the level of improvement of AI. Methods: Forty-nine children (mean age 10.2 years ± 2.7) diagnosed with AI graded their degree of asthenopia on the VAS before and after a 12-week treatment period wearing individually dispensed reading glasses. Results: The improvement in accommodation after treatment was statistically significant (p < 0.001) and 83.7% of the children obtained normal accommodative amplitude in relation to age. The reduction in asthenopic symptoms as graded with the VAS was also statistically significant (p < 0.001) after treatment and 89.9% of the children obtained a normal VAS score. However, no correlation between the degree of accommodative deficiency and the VAS grading could be found, neither before nor after treatment. Discussion: Based on these results we conclude that the visual analogue scale (VAS) cannot be used as an instrument to indicate the degree of accommodative deficiency nor can it be used to indicate the level of improvement during the course of treatment. However, the VAS can be used as an instrument to verify and document whether or not asthenopic symptoms are present, and therefore also to indicate when symptoms have been relieved.