Spectacle Correction Research Articles

This issue of ACTA, printed and electronic

This issue of <i>ACTA</i>, printed and electronic

Quality of Vision with Spectacles, Special Silicone Hydrogel and Gas Permeable Contact Lenses in Keratoconic Patients

ABSTRACT Purpose To evaluate optical quality and visual function in keratoconus patients corrected with RGP contact lenses and a novel special design of silicone hydrogel contact lens. Materials and methods Twelve eyes of six patients with keratoconus were enrolled to experience a new soft contact lens (Soft-K) for keratoconus made of a silicone-hydrogel material and the outcomes were compared to the performance with gas permeable lenses and spectacles. The three situations were compared for monocular and binocular high (100%) and low contrast (10%) ETDRS LogMAR visual acuity and contrast sensitivity function (CSF). Results On average, there was an improvement of more than two lines in visual acuity over spectacle correction and this is statistically significant for both gas permeable (GP) and Soft-K lens (p &lt; 0.001). Visual acuity was not significantly different between GP and Soft-K lens for high contrast acuity but was slightly higher with GP lens for low contrast under binocular conditions. Monocular CSF showed a marked improvement with the Soft-K lens and GP, compared to spectacles correction, particularly for medium and high frequencies; conversely. Conclusion Soft-K silicone hydrogel soft contact lens produces a clinical and statistically significant improvement in visual acuity and contrast sensitivity function over spectacle correction. How to cite this article González-Méijome JM, Peixoto-de- Matos SC, Queiros A, Jorge JM, Diaz-Rey A. Quality of Vision with Spectacles, Special Silicone Hydrogel and Gas Permeable Contact Lenses in Keratoconic Patients. Int J Kerat Ect Cor Dis 2013;2(2):56-59.

Incidence of the refractive errors in children 3 to 9 years of age, in the city of Tetovo, Macedonia

Abstract Objective To determine the incidence of refractive errors at children 3 to 9 years of age in the area of Tetovo, Macedonia in rural and urban population. Methods Population-based cross-sectional samples of children 3 to 9 years in rural and urban population were obtained through full ophthalmologic examination, and they underwent slit-lamp examination, ocular motility and refraction. They were presenting uncorrected and best-corrected visual acuity, along with refractive error under topical cycloplegia. Children 3 to 6 years of age with a visual acuity of 20/40 or worse and those 6 to 9 years of age with a visual acuity of 20/30 or worse underwent a complete ophthalmic examination to determine the cause of visual impairment. A spherical equivalent of -0.5 diopter (D) or worse was defined as myopia, +2.50 D or more was defined as hyperopia and a cylinder refraction greater than 0.75 D was considered astigmatism plus or minus. Results The uncorrected visual acuity was 20/45 or worse in the better eye of 119 children, 59 male / 60 female (5.1% of participants). According to results of cycloplegic refraction, 1.6% of the children were myopic, 7.3% were hyperopic and the incidence rate of astigmatism was approximately 0.7%. In the multivariate logistic regression myopia and hyperopia were correlated with age ( P = 0.040 and P Conclusions The study showed a considerable prevalence rates of refractive errors myopia, hypermethropia, astigmatism and amblyopia at children of 3-9 years of age in Tetovo. There was no correlation between sex of the children's and the refractive errors founds. There was a correlation with the need for corrective spectacles and the refractive errors they represent. Refractive errors was registered in high percentage at rural area than in urban area. Although with best corrected vision the prevalence of impairment was less in urban than in rural populations, blindness remained nearly twice as high in the rural population as in the urban population with both baseline and best corrected visual acuity.

Visual Outcome in Isoametropic Amblyopic Children With High Hyperopia and the Effect of Therapy on Retinal Thickness

To assess correlations between associated factors and treatment outcome of isoametropic amblyopia attributable to high hyperopia in children and to evaluate changes in retinal thickness during amblyopic treatment. Retrospective (visual outcome) and prospective (retinal thickness) study. Isoametropic (spherical equivalent ≥5.00 diopters in both eyes) amblyopic subjects (n = 217) with corrected visual acuity (VA) ≤0.5 (20/40) for children <5 years old and VA ≤0.6 (20/32) for children 6-10 years old were included. Sixty-nine of these children had refractive accommodative esotropia. All subjects were treated by full-time wearing of optical correction. The magnitude of spherical equivalent hyperopia, age at first treatment, VA, treatment duration, and binocular alignment were analyzed. Thicknesses of the retinal macula and nerve fiber layer were measured using optical coherence tomography in selected amblyopic children (n = 27) during treatment and in control subjects (n = 31). The mean follow-up was 28.8 months. The age at first optical correction ranged from 3 to 10 years. The mean VA improved from 0.38 to 0.82, with 74.7% having acuity ≥0.8 and 28.6% having acuity ≥1.0. VA improvement was positively correlated with duration of treatment and negatively correlated with age at first correction. Foveal thickness slightly decreased after treatment; however, it was not correlated with visual improvement. Visual acuity of isoametropic amblyopia improved satisfactorily with spectacle correction and vision therapy. Treatment duration had the greatest impact on VA improvement. Age at first correction also influenced VA improvement but was not a good clinical predictor. Foveal thinning occurring with treatment was not correlated with visual improvement.

Résultats fonctionnels de la chirurgie de la cataracte de l’adulte

The treatment of cataract blindness is surgical, allowing restored vision. The purpose of this study was to evaluate the functional results of cataract surgery in adults in a tertiary care referral center. Prospective study of 2012 eyes operated for adult cataract from September 1, 2009 to August 31, 2010 (12 months). The results were analyzed by the Monitoring Cataract Surgical Outcomes software (MCSO). The postoperative functional data and the causes of poor outcomes were identified. A total of 1044 women (51.9%) and 968 men (48.1%) underwent cataract surgery. Mean age was 65 years. Extracapsular cataract extraction (ECCE), and manual sutureless small incision cataract surgery (SICS) with posterior chamber IOL implantation in 98%, were the main surgical techniques. Functional results indicated that 45.5% of our patients had good visual acuity (≥3/10) with current spectacles, 33% had limited visual acuity (1/10-2/10), and 21.6% had poor visual acuity (<1/10). The proportion of patients with good results improved with best spectacle correction to 63%, vs. 22.9% with limited visual acuity and 14.1% with poor outcomes. The causes of poor outcomes were mainly related to surgical complications (42.1%) and refractive errors (34.8%). These results are inferior to WHO standards, which recommend a rate greater than or equal to 80% for good outcomes and a rate below 5% for bad outcomes. The identification of the causes of poor outcomes underscores the importance of improving surgical skills and the need for postoperative refraction.

Prevalence and pattern of refractive errors among primary school children in Al Hassa , Saudi Arabia.

Some 12.8 million in the age group 5–15 years are visually impaired from uncorrected or inadequately corrected refractive errors. In Saudi Arabia, the size of this public health problem is not well defined especially among primary schoolchildren. The purpose of this cross-sectional study was to assess the prevalence and pattern of refractive errors among primary school children in Al Hassa, Saudi Arabia. A total of 2246 Saudi primary school children aged 6 to 14 years of both genders were selected using multistage sampling method form 30 primary schools located in the three different areas of Al Hassa. School children were interviewed to collect demographics and vision data using a special data collection form followed by screening for refractive errors by trained optometrists within the school premises using a standardized protocol. Assessment of visual acuity and ocular motility evaluation were carried out and cover-uncover test was performed. Children detected with defective vision were referred for further examination employing subjective refraction with auto refractometer and objective refraction using streak retinoscopy after 1% cyclopentolate. Of the screened school children (N=2002), the overall prevalence of refractive errors was 13.7% (n=274), higher among females (Odds ratio, OR=1.39, P=0.012) and significantly more among students of rural residence (OR=2.40, P=0.001). The prevalence of refractive errors was disproportionately more among those aged 12-14 years (OR=9.02, P=0.001). Only 9.4% of students with poor vision were wore spectacles for correction. Myopia was the most commonly encountered refractive error among both genders (65.7% of the total errors encountered). Uncorrected refractive errors affected a sizable portion of primary school children in Al Hassa, Saudi Arabia. Primary schoolchildren especially females, rural and older children represents high risk group for refractive errors for which the included children were unaware.

Cost of Intraocular Lens versus Contact Lens Treatment after Unilateral Congenital Cataract Surgery: Retrospective Analysis at Age 1 Year

To describe the differences in treatment costs for infants randomized to contact lens correction versus primary intraocular lens (IOL) implantation after unilateral cataract surgery in the Infant Aphakia Treatment Study (IATS). Retrospective cost analysis of a prospective, randomized clinical trial based on Georgia Medicaid data and the actual costs of supplies used. The IATS is a randomized, multicenter (n=12) clinical trial comparing treatment of aphakia with a primary IOL or contact lens in 114 infants with unilateral congenital cataract. Infants underwent cataract surgery with or without placement of an IOL. The mean cost of cataract surgery and all additional surgeries, examinations, and supplies used up to 12 months of age. The mean cost of treatment for a unilateral congenital cataract with primary IOL implantation was $14 752 versus $10 726 with contact lens correction. The initial cataract surgery accounted for approximately 50% of the treatment costs for both groups. Contact lens costs accounted for 15% ($1600/patient) in the aphakic group, whereas glasses costs represented only 4% ($535/patient) in the IOL group. The increased costs in the IOL group were primarily due to the higher cost of cataract surgery in this group ($7302 vs. $5357) and the cost of additional operations. For IATS patients up to 12 months of age, cataract surgery coupled with IOL implantation and spectacle correction was 37.5% (∼$4000) more expensive than cataract surgery coupled with contact lens correction. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Exotropia in children with high hyperopia

To describe the clinical characteristics, treatment, and subsequent clinical course of children with exotropia and high hyperopia. The medical records of 26 patients seen between 1990 and 2009 who had an exotropia and ≥4.00 D of hyperopia were retrospectively reviewed. We analyzed the clinical characteristics, treatments, and subsequent alignment outcomes. A total of 26 patients between the ages of 2.5 months and 9 years were included. Of these, 15 had associated medical conditions or developmental delay. Of 22 patients with measured visual acuities, 19 had amblyopia (10 unilateral, 9 bilateral). None of the patients demonstrated fine stereoacuity. Twenty-three exotropic children were treated with spectacles: 15 were fully corrected, 10 of whose exotropia improved; 8 received partial correction of their hyperopia, 3 of whose exotropia improved. Six patients who presented with large, poorly controlled exotropia and did not improve with spectacle correction required strabismus surgery. Children with high hyperopia and exotropia are likely to have developmental delay or other systemic diseases, amblyopia, and poor stereopsis. Treatment of high hyperopia in exotropic children with their full cycloplegic refraction can result in excellent alignment.

Effects of wearing yellow spectacles on visual skills, reading speed, and visual symptoms in children with reading difficulties

Possible beneficial effects of yellow-tinted spectacle lenses on binocular vision, accommodation, oculomotor scanning, reading speed and visual symptoms were assessed in children with reading difficulties. A longitudinal prospective study was performed in 82 non-dyslexic children with reading difficulties in grades 3-6 (aged 9-11 years) from 11 elementary schools in Madrid (Spain). The children were randomly assigned to two groups: a treatment (n = 46) and a without-treatment group (n = 36). Children in the treatment group wore yellow spectacle lenses with best correction if necessary over 3 months (in school and at home). The tests were first undertaken without the yellow filter. With best spectacle correction in each subject, measurements were made of: distance and near horizontal heterophoria, distance and near horizontal fusional vergence ranges, the accommodative convergence/accommodation (AC/A) ratio, near point of convergence (NPC), stereoacuity, negative relative accommodation (NRA) and positive relative accommodation (PRA), monocular accommodative amplitude (MAA), binocular accommodative facility (BAF), oculomotor scanning, and reading speed (words per minute). The Convergence Insufficiency Symptom Survey (CISS) questionnaire was completed by all children. After the 3-month period, measurements were repeated with the yellow lenses (treatment group) or without the yellow lenses (without-treatment group) but with refractive correction if needed. Over the 3 months, the two groups showed similar mean changes in the variables used to assess binocular vision, accommodation, oculomotor scanning, and reading speed. However, mean relative changes in convergence insufficiency symptoms differed significantly between the groups (p = 0.01). No effects of wearing yellow spectacles emerged on binocular vision, accommodation, oculomotor scanning, and reading speed in children with reading difficulties. The yellow filter had no effect even in children with low MAA and BAF. The reduction in visual symptoms observed in children with reading difficulties using the yellow filters was clinically insignificant.

Rigid gas‐permeable contact lens for visual rehabilitation in aphakia following trauma

PurposeThe aim here was to study the safety and efficacy of fitting a rigid gas‐permeable contact lens (RGP CL) for visual rehabilitation in patients with ocular trauma.MethodsA retrospective study was performed on 17 aphakic eyes of patients (16 men and one woman) after surgery for ocular trauma. RGP CLs (including nine brown‐tinted lenses) were fitted unilaterally for visual rehabilitation in these patients. The uncorrected vision, spectacle visual acuity and contact lens (CL) visual acuity were recorded.ResultsSeventeen patients were selected on the basis that they had undergone surgery following ocular trauma. All eyes fitted were aphakic (n = 17) and nine eyes were fitted with brown‐tinted RGP lenses to compensate for traumatic aniridia. All eyes were fitted with RGP CL. A visual acuity of 6/20 or better was seen in seven eyes (41.2 per cent) with spectacle correction and in 15 eyes (88.2 per cent) with CL correction. A visual acuity of 6/12 or better was seen in four eyes (23.5 per cent) and 10 eyes (58.8 per cent), respectively.ConclusionsA RGP CL is one of the methods available for treating refractive abnormalities in traumatic unilateral aphakia. The procedure is effective, safe and tolerable. RGP CLs can correct the vision of patients with irregular corneal astigmatism. The brown‐tinted RGP CL can improve the symptoms of photophobia and the cosmetic appearance of brown eyes.

Modeling the Effect of Forward Scatter and Aberrations on Visual Acuity after Endothelial Keratoplasty

To evaluate the effects on visual acuity of forward scatter and aberrations typical of those after Descemet stripping endothelial keratoplasty (DSEK). Twenty normal eyes of 20 subjects (ages 22-57 years) were examined with best spectacle correction. Under photopic conditions, high-contrast visual acuities (HCVAs) were measured by using ETDRS charts. Visual acuity was also measured by using aberrated charts that simulated the typical high-order aberrations at 12 months after DSEK. Forward scatter was induced by viewing the eye charts through a 1-mm-thick layer of scattering solution (Amco Clear, at a concentration of 4000 nephelometric turbidity units) and was measured with a straylight meter. Forward scatter increased from 1.19 ± 0.11 log straylight parameter (log[s]; mean ± SD) without induced scatter to 1.57 ± 0.06 log(s) with induced scatter (P < 0.001). Induced scatter reduced HCVA on the nonaberrated chart by 2.7 Snellen letters, from 20/19 (Snellen equivalent) to 20/21 (P < 0.001) and by 2.1 letters on the aberrated chart, from 20/25 to 20/28 (P = 0.005). Addition of aberrations reduced HCVA by more than twice the number of Snellen letters than did induced scatter, by 6.4 letters with low scatter (P < 0.001), and by 5.8 letters with high scatter (P < 0.001). Under typical clinical testing conditions, increased forward scatter has minimal effect on visual acuity. High-order aberrations are a more likely cause of degraded visual acuity than is forward scatter in eyes with clear corneas after DSEK.

Three-Dimensional Display-Induced Transient Myopia and the Difference in Myopic Shift between Crossed and Uncrossed Disparities

To investigate whether three-dimensional (3D) images cause nearwork-induced transient myopia (NITM) more than 2D images and whether there is any difference between 3D images with crossed and uncrossed disparities in the development of NITM. Twenty-five volunteers, enrolled in this study, watched 2D and 3D movies and read 3D texts with crossed and uncrossed disparities for 2 to 3 hours with spectacle correction. The viewing distance was 50 to 70 cm. The refractive error was measured before and after each visual task. If there was a myopic shift after a task, the refractive error was measured at 3-minute intervals until it was resolved. The changes in the refractive error and the amount of NITM were evaluated and compared. The mean age of volunteers was 27.8 ± 2.87 years, and the mean refractive error before the visual tasks was -4.19 ± 2.87 diopters (D). Thirteen subjects (52%) showed NITM after watching a 2D movie, whereas 20 subjects (80%) had NITM after a 3D movie (P = 0.037). The mean extent of NITM was 0.36 ± 0.27 D after watching a 3D movie and 0.10 ± 0.28 D after a 2D movie (P = 0.002). The 3D text with crossed disparity significantly induced NITM (P < 0.001), but that with uncrossed disparity did not. There was a tendency for the NITM to persist longer after subjects watched a 3D movie than after a 2D movie. Viewing 3D images with crossed disparity induced a greater degree of NITM than 2D images. These results suggest that the greater NITM induced by 3D images may have a greater effect on the development and progression of permanent myopia.

Long-Term Effect of Overnight Orthokeratology on Axial Length Elongation in Childhood Myopia: A 5-Year Follow-Up Study

Our prospective study was conducted to compare axial length elongation in myopic children receiving long-term overnight orthokeratology (OK) treatment to those wearing spectacles as controls. There were 59 subjects enrolled in this study. The OK group comprised 29 subjects who matched the inclusion criteria for OK. The control group comprised 30 subjects who also matched the inclusion criteria for OK, but preferred spectacles for myopia correction. Axial length was measured periodically for 5 years using an IOLMaster device, and the time course of changes was evaluated and compared between the groups. A total of 43 subjects (22 and 21 in the OK and control groups, respectively) completed the 5-year follow-up examinations. At baseline, the mean age ± SD was 10.04 ± 1.43 and 9.95 ± 1.59 years, the spherical equivalent refractive error was -1.89 ± 0.82 and -1.83 ± 1.06 diopters (D), and the axial length was 24.09 ± 0.77 and 24.22 ± 0.71 mm in the OK and control groups, respectively, with no significant differences between the groups. The increase in axial length during the 5-year study period was 0.99 ± 0.47 and 1.41 ± 0.68 mm for the OK and control groups, respectively, and the difference was statistically significant (P = 0.0236, unpaired t-test). The annual increases in axial length were significantly different between the groups for the first (P = 0.0002), second (P = 0.0476), and third years (P = 0.0385), but not for the fourth (P = 0.0938) and fifth (P = 0.8633) years. There were no severe complications throughout the study period. The current 5-year follow-up study indicated that OK can suppress axial length elongation in childhood myopia.

Blindness and Visual Impairment in an Urban West African Population: The Tema Eye Survey

To determine the prevalence, causes, and risk factors of blindness and visual impairment among persons aged 40 years or older residing in an urban West African location. Population-based, cross-sectional study. A total of 5603 participants residing in Tema, Ghana. Proportionate random cluster sampling was used to select participants aged 40 years or older living in the city of Tema. Presenting distance visual acuity (VA) was measured at 4 and 1 m using a reduced logarithm of the minimum angle of resolution tumbling E chart and then with trial frame based on autorefraction. A screening examination was performed in the field on all participants. Complete clinical examination by an ophthalmologist was performed on participants with best-corrected visual acuity (BCVA) <20/40 or failure of any screening test. Age- and gender-specific prevalence, causes, and risk factors for blindness (VA of <20/400 in the better eye, World Health Organization definition) and visual impairment (VA of <20/40 in the better eye). A total of 6806 eligible participants were identified, of whom 5603 (82.3%) participated in the study. The mean age (± standard deviation) of participants was 52.7 ± 1 0.9 years. The prevalence of visual impairment and blindness was 17.1% and 1.2%, respectively. After refraction and spectacle correction, the prevalence of visual impairment and blindness decreased to 6.7% and 0.75%, respectively, suggesting that refractive error is the major correctable cause of visual impairment and blindness in this population. Of 65 subjects with a VA <20/400, 22 (34%) were correctable with refraction, 21 to the level of visual impairment and 1 to normal. The remaining 43 patients (66%) had underlying pathology (cataract in 19, glaucoma in 9, nonglaucomatous optic neuropathy in 3, corneal opacities in 3, retinal disease in 3, and undetermined in 5) that prevented refractive correction. Increased age was a significant risk factor for blindness and visual impairment. There is a high prevalence of blindness and visual impairment among those aged ≥ 40 years in Tema, Ghana, West Africa. Refractive error is a major cause of blindness and visual impairment in this population, followed by cataract, glaucoma, and corneal disease.

Prevalence and Correction of Near Vision Impairment at Seven Sites in China, India, Nepal, Niger, South Africa, and the United States

To estimate the prevalence of near vision impairment and use of corrective spectacles among middle-aged and older adults in different settings and ethnic groups. Population-based, cross-sectional study. People aged ≥ 35 years were randomly selected with cluster sampling in 4 rural settings in Shunyi (China), Kaski (Nepal), Madurai (India), and Dosso (Niger); 1 semi-urban area in Durban (South Africa); and 2 urban settings in Guangzhou (China) and Los Angeles (USA). Near visual acuity (VA), with and without presenting near correction, was measured at 40 cm using a logMAR near vision tumbling E chart. Subjects with uncorrected binocular near VA ≤ 20/40 were tested with plus spheres to obtain the best-corrected binocular VA. A total of 17 734 persons aged ≥ 35 years were enumerated and 14 805 (83.5%) were examined. The age- and sex-standardized prevalence of uncorrected near vision impairment (VA ≤ 20/40) ranged from 49% in Dosso to 60% in Shunyi and Guangzhou, 65% in Kaski and Los Angeles, and 83% in Madurai and Durban. The prevalence of near vision impairment based on best-corrected visual acuity was less than 10% in Guangzhou, Kaski, Durban, and Los Angeles, but as high as 23% in Madurai. In multiple logistic regression models, uncorrected near vision impairment was associated with older age (odds ratio [OR] = 1.14, P < .001) and female sex (OR = 1.12, P = .027), but not with educational level (OR = 1.01, P = .812). Over 90% of people in need of near refractive correction in rural settings did not have the necessary spectacles. These rates were 40% in urban settings. By 50 years of age, the majority of people suffer from near vision impairment, most of which can be corrected optically. Over 90% of those in need of near refractive correction in rural settings do not have the necessary spectacles.

Foldable iris‐fixated intraocular lens implantation in children

To describe the results of foldable iris-fixated intraocular lens (IOL) implantation in children. Children with high bilateral or unilateral myopia who were intolerant of spectacle or contact lens correction were implanted with an iris-fixated foldable IOL and prospectively followed. We measured pre- and postoperative visual acuity, refraction, endothelial cell density (ECD) and National Eye Institute Visual Functioning Questionnaire-25. Eleven eyes of six children were implanted. Indications were high bilateral myopia in children with comorbid neurobehavioural disorders, high anisometropia and high myopic astigmatism. Mean preoperative spherical equivalent (SE) refraction was -14.6 dioptres (D)±4.2 SD. Mean follow-up was 15 months. Postoperative SE refraction was -2.40 D±2.40 SD. Corrected distance visual acuity (CDVA) improved from mean logMAR 0.84±0.4 SD to postoperative 0.67±0.34 SD (p=0.005). CDVA was reduced because of coexistent ocular disorders and amblyopia. Vision-related quality of life (QOL) measures improved significantly. There were no intraoperative or postoperative serious complications. Foldable iris-fixated IOL insertion can give a significant improvement in vision and in vision-related QOL in a subset of paediatric patients with special refractive needs who are intolerant to conventional treatment. Long-term follow-up is required for monitoring of ECD.

Effect of Simulated Astigmatic Refractive Error on Reading Performance in the Young

Few studies have specifically investigated the functional effects of uncorrected astigmatism on measures of reading fluency. This information is important to provide evidence for the development of clinical guidelines for the correction of astigmatism. Participants included 30 visually normal, young adults (mean age, 21.7 ± 3.4 years). Distance and near visual acuity and reading fluency were assessed with optimal spectacle correction (baseline) and for two levels of astigmatism, 1.00 diopter cylinder (DC) and 2.00 DC, at two axes (90 and 180°) to induce both against-the-rule (ATR) and with-the-rule (WTR) astigmatism. Reading and eye movement fluency were assessed using standardized clinical measures including the test of Discrete Reading Rate (DRR), the Developmental Eye Movement test (DEM), and by recording eye movement patterns with the Visagraph (III) during reading for comprehension. Both distance and near acuity were significantly decreased compared with baseline for all the astigmatic lens conditions (p < 0.001). Reading speed with the DRR for N16 print size was significantly reduced for the 2.00 DC ATR condition (a reduction of 10%), whereas for smaller text sizes, reading speed was reduced by up to 24% for the 1.00 DC ATR and 2.00 DC condition in both axis directions (p < 0.05). For the DEM, subtest completion speeds were significantly impaired, with the 2.00 DC condition affecting both vertical and horizontal times and the 1.00 DC ATR condition affecting only horizontal times (p < 0.05). Visagraph reading eye movements were not significantly affected by the induced astigmatism. Induced astigmatism impaired performance on selected tests of reading fluency, with ATR astigmatism having significantly greater effects on performance than did WTR, even for relatively small amounts of astigmatic blur of 1.00 DC. These findings have implications for the minimal prescribing criteria for astigmatic refractive errors.

A method to design aspheric spectacles for correction of high-order aberrations of human eye

Aiming at the correction of high-order aberrations of human eye with spectacles, a design method of aspheric spectacles is proposed based on the eye’s wavefront aberrations data. Regarding the eyeball and the spectacles as a whole system-the lens-eye system-the surface profiles of the spectacles are achieved by optimization procedure of lens design. Different from the conventional optometry, in which the refraction prescription is acquired with a visual chart, the design takes into account the two aspects of actual human viewing, eyeball rolling and certain distinct viewing field. The rotation angle of eyeball is set to be ±20° as wearing spectacles, and the field of view is set to be ±7° which is especially important as watching screen display. The individual eye model is constructed as the main part of the lens-eye system. The Liou eye model is modified by sticking a thin meniscus lens to the crystalline lens. Then the defocus of the individual eye is transferred to the front surface of the meniscus lens, and the astigmatism and high-order aberrations are transferred to the front surface of the cornea. 50 eyes are involved in this research, among which 36 eyes have good enough visual performance already after sphero-cylindrical correction. 10 eyes have distinct improvement in vision and 4 eyes have no visual improvement by further aspheric correction. 6 typical subject eyes are selected for the aberrations analysis and the spectacles design in this paper. It is shown that the validity of visual correction of aspheric lens depends on the characteristics of the eye’s wavefront aberrations, and it is effective for the eye with larger astigmatism or spherical aberration. Compared with sphero-cylindrical correction only, the superiority taken by the aspheric correction is mainly on the improvement of MTF at a larger field of view. For the best aspheric correction, the MTF values increase by 18.87%, 38.34%, 44.36%, 51.29% and 57.32% at the spatial frequencies of 40, 80, 100, 125 and 150 cycles/mm, respectively.

Refractive Error and Presbyopia in Timor-Leste: The Impact of 5 Years of a National Spectacle Program

To characterize refractive error, presbyopia, and spectacle correction among adults aged ≥40 years in Timor-Leste in 2010 and examine the impact of the National Spectacle Program by comparing results to those obtained 5 years earlier. A population-based, cross-sectional survey sampled 50 clusters of 45 people each. Participants with uncorrected and undercorrected refractive error (presenting visual acuity <6/18, but ≥6/18 in the better eye with pinhole), uncorrected and undercorrected presbyopia (<N8 binocular), corrected refractive error (≥6/18 in the better eye with presenting spectacles), and corrected presbyopia (binocular ≥N8 with presenting spectacles) were identified. Willingness to wear and to pay for spectacles was elicited. Data were adjusted for sex, age, and urban/rural domicile, to compare results from 2005 and 2010. A participation rate of 89.5% (n = 2014) was achieved. The 2010 sex-age-domicile-adjusted parameters were as follows: 3.7% (95% confidence interval [CI], 2.8%-4.5%) met refractive error need; 9.6% (95% CI, 8.3%-10.9%) unmet refractive error need; 27.6% (95% CI, 22.2%-32.9%) refractive error correction coverage; 8.6% (95% CI, 7.4%-9.8%) met presbyopia need; 41.8% (95% CI, 39.7%-44.0%) unmet presbyopia need; and, 17.0% (95% CI, 14.7%-19.3%) presbyopia correction coverage. Refractive error correction coverage was significantly higher in 2010 than in 2005 (8.0%; 95% CI, 4.5%-11.6%), but presbyopia correction coverage was unchanged. Almost all the 2010 sample (99.5%) were willing to wear spectacles if needed. Sex-age-domicile-adjusted willingness to pay at least US$1.00 for spectacles was 56.9% (95% CI, 54.7%-59.1%) in 2010, significantly greater than in 2005 (47.2%; 95% CI, 44.5%-49.9%). The National Spectacle Program has not produced uniform improvement across all service indicators. Evidence-based enhancements may now be initiated.

Clinical and molecular analysis of children with central pulverulent cataract from the Arabian Peninsula

AimTo clinically and genetically characterise central pulverulent cataract in a consecutive cohort of children from the Arabian Peninsula who were referred for ophthalmic evaluation.MethodsOphthalmic examination, homozygosity mapping in a consanguineous...