Ophthalmic and Physiological Optics最新文献

Purpose: To introduce a novel methodology for subjective refraction based on power vectors with a conventional phoropter.

Methods: A conventional phoropter was used to measure power vector components of refraction (M, J₀ and J₄₅) directly by using the sphere power (for M measurement) and the cylinder power combined with the Jackson cross-cylinders (for J₀ and J₄₅ measurements). Conventional subjective refraction was also performed, and this result was mathematically transformed into power vector notation for comparison purposes. Visual acuities with the conventional prescription and the quasi-vector-based prescription were compared.

Results: Refractive error from 40 healthy participants was measured by conventional and quasi-vector-based subjective refraction. No differences were found between methods for any of the power vector components of refraction (p > 0.21 in all cases). The visual acuity achieved with the prescriptions yielded similar values (p = 0.85).

Conclusions: Subjective refraction can be measured directly in power vector notation using a conventional phoropter without any additional adaptation and computation.

Purpose: To evaluate the value of enhanced optometric services for managing neovascular age-related macular degeneration (nAMD) and glaucoma in primary care optometry services, instead of hospital eye services (HES).

Methods: Seven enhanced optometric service pathways in primary care in Wales were assessed with a mixed-methods approach: three for nAMD and four for glaucoma. The methods were a patient-related experience measure (PREM), a Realist Review and Evaluation involving both patients and staff, a discrete event simulation model estimating the economic impact of the pathways and a workforce survey of optometrists to gauge capability and capacity.

Results: Patient-related experience measure responses (802) indicated that primary care experience was comparable to that of HES. Utilising enhanced optometric services in primary care resulted in reduced wait times compared with HES, with suspected nAMD shortened to 4-5 days and glaucoma monitoring to 5 days. Waiting lists were dramatically reduced with primary care-based services to just three people waiting for nAMD and five for glaucoma, compared with 216 and 5691 people, respectively, in HES. Consultant ophthalmologist time was reduced from 57% to 15%-16% for nAMD services and from 48% to 22%-23% for glaucoma services. Integrating enhanced optometric services into primary care incurred a similar cost. The workforce survey confirms that optometrists possess the skills and qualifications and are willing to deliver these enhanced optometric services. The Realist Review and Evaluation revealed that clear patient communication, effective coordination and strong interprofessional communication between optometrists and ophthalmologists along with a shared electronic record are crucial to the success of this change.

Conclusion: Providing enhanced optometric services in primary care for nAMD and glaucoma brings substantial benefits for the UK National Health Service and patients, including reduced waiting times, waiting lists and released HES capacity. The success of this transition hinges on clear patient communication, administrative co-ordination and effective interprofessional communication.

Aim: To develop an accommodating, wide-angle, schematic eye for emmetropia and myopia in which spectacle refraction and accommodation level are input parameters.

Method: The schematic eye is based on an earlier unaccommodated refraction-dependent eye for myopia developed by Atchison in 2006. This has a parabolic gradient index lens and parameters derived from biometric and optical measurements on young adults. Several parameters are linearly dependent upon spectacle refraction (anterior radius of curvature of the cornea, axial length and vertex radii of curvature and conic asphericities of a biconic retina). The new accommodated schematic eye incorporates accommodation-dependent changes in several lens-related parameters. These changes are based on literature values for anterior chamber depth, lens thickness, vitreous chamber depth, lens surface radii of curvature and lens front surface asphericity. A parabolic variation of refractive index with relative distance from the lens centre is retained, with the same edge and centre refractive indices as the earlier model, but the distribution has been manipulated to maintain focus near the retina for the emmetropic case at 0 and 4 D accommodation. The asphericity of the lens back surface is changed so that spherical aberration and peripheral refraction approximately match typical literature trends. The model is used to compare spherical aberration and peripheral refraction in eyes with up to 4 D of myopia and 4 D of accommodation.

Results: The levels of spherical aberration in the unaccommodated schematic eyes are similar to literature values for young adults, but the changes in spherical aberration with accommodation are approximately two-thirds of that found in an experimental study. As intended, peripheral refractions in the accommodated schematic eyes are similar to those of their unaccommodated counterparts.

Conclusion: The wide-angle model extends the range of schematic eyes to include both refraction and accommodation as variable input parameters. It may be useful in predicting aspects of retinal image quality.

Purpose: During refractive development, eye growth is controlled by a combination of genetically pre-programmed processes and retinal feedback to minimise the refractive error. This work presents a basic differential model of how this process may take place.

Methods: The description starts from two bi-exponential descriptions of the axial power P_ax (or dioptric distance) and total refractive power P_eye, the difference between which corresponds with the spherical refractive error S. This description is rewritten as an ordinary differential equation and supplemented by a retinal feedback function that combines retinal blur (closed loop) with a term describing excessive axial growth (open loop). This model is controlled by a total of 18 parameters that allow for a wide variety of developmental behaviours.

Results: The proposed model reproduces refractive development growth curves found in the literature for both healthy and myopic eyes. An early onset of myopisation, a large growth term and a high minimum for the crystalline lens power all lead to higher degrees of myopia. Assigning more importance to the feedback than to the pre-programmed growth makes the model more sensitive to myopogenic influences. Applying refractive corrections to the model, undercorrection is found to produce more myopia. The model compensates for a low-powered imposed lens and can return to (near) emmetropia if that imposed lens is removed quickly thereafter. Finally, simulating the effect of a diffuser leads to high myopia.

Conclusion: Using a series of basic assumptions, the proposed model recreates many well-known experimental and clinical results about refractive development from the literature while placing them in a standardised context. This contributes to a broader understanding of the origins of refractive errors, and future versions may help in the development of solutions for myopia control.

Purpose: To evaluate the short-term (1 week after completion of treatment) effect of office-based vergence and anti-suppression therapy (OBVAT) on binocular vision and accommodative function when compared to observation alone in children with small-to-moderate angle intermittent exotropia (IXT).

Methods: In this single-masked (examiner masked), two-arm, single-centre randomised clinical trial, 40 participants, 6 to <18 years of age with untreated IXT were randomly assigned to OBVAT or observation alone. Participants assigned to therapy received 16 weeks of OBVAT (60 min per visit, once per week) with home reinforcement (15 min per day, 5 days a week). Therapy included vergence, accommodation and anti-suppression techniques. This paper reports the results of clinical measures of binocular vision and accommodation, including fusional vergence, near point of convergence, vergence facility, amplitude of accommodation, the Worth 4-dot test and the Fusion Maintenance Score (FMS).

Results: Treatment group differences at the primary outcome visit significantly favoured the OBVAT group (n = 20) over the observation group (n = 16) in negative fusional vergence break point at both distance (p ≤ 0.001; r = 0.58) and near (adjusted mean difference: 12.3 Δ; 95% CI: 5.3-19.3 Δ; p = 0.001; partial eta squared: 0.28), positive fusional vergence break point at both distance (p = 0.009; r = 0.43) and near (adjusted mean difference: 20.6 Δ; 95% CI: 11.8-29.4 Δ; p ≤ 0.001; partial eta squared: 0.41), vergence facility (adjusted mean difference: 5.6 cpm; 95% CI: 1.9-9.4 cpm; p = 0.005; partial eta squared: 0.22) and the FMS (p = 0.007; r = 0.44).

Conclusions: In this randomised clinical trial of participants aged 6 to <18 years with IXT, those in the OBVAT group had a significantly better fusional vergence range, vergence facility, near Worth 4-dot test result and FMS than the observation group at the 17-week visit. The improvement in these areas further support the effectiveness of OBVAT for improving IXT.

Background: Active vision therapy for amblyopia shows good results, but there is no standard vision therapy protocol. This study compared the results of three treatments, two combining patching with active therapy and one with patching alone, in a sample of children with amblyopia.

Methods: Two protocols have been developed: (a) perceptual learning with a computer game designed to favour the medium-to-high spatial frequency-tuned achromatic mechanisms of parvocellular origin and (b) vision therapy with a specific protocol and 2-h patching. The third treatment group used patching only. Fifty-two amblyopic children (aged 4-12 years), were randomly assigned to three monocular treatment groups: 2-h patching (n = 18), monocular perceptual learning (n = 17) and 2-h patching plus vision therapy (n = 17). Visual outcomes were analysed after 3 months and compared with a control group (n = 36) of subjects with normal vision.

Results: Visual acuity (VA) and stereoacuity (STA) improved significantly after treatment for the three groups with the best results for patching plus vision therapy, followed by monocular perceptual learning, with patching only least effective. Change in the interocular difference in VA was significant for monocular perceptual learning, followed by patching. Differences in STA between groups were not significant. For VA and interocular differences, the final outcomes were influenced by the baseline VA and interocular difference, respectively, with greater improvements in subjects with poorer initial values.

Conclusions: Visual acuity and STA improved with the two most active treatments, that is, vision therapy followed by perceptual learning. Patching alone showed the worst outcome. These results suggest that vision therapy should include monocular accommodative exercises, ocular motility and central fixation exercises where the fovea is more active.

Background: The certificate of vision impairment has an important role in enabling access to support for people with vision impairment (VI) and the provision of epidemiological data regarding sight loss. However, the rates of certification may not accurately reflect the number of people living with certifiable VI.

Methods: Observational data from a national primary care low vision rehabilitation service between 1 April 2021 and 31 March 2022 were analysed. Descriptive statistics were used to describe the certification status of patients with certifiable VI. For patients with age-related macular degeneration (AMD) and best-corrected visual acuity of 6/60 or worse, logistic regression was undertaken to assess the effects of patient characteristics on certification status.

Results: For patients with AMD and certifiable levels of visual acuity, 41.00% (n = 426) were not certified. The reported certification was 60.09% (n = 256) and 58.24% (n = 357) for neovascular AMD and atrophic AMD, respectively. Existing patients of the service were 3.87 times more likely to be certified than new patients (OR 3.87, 95% CI 2.7-5.4). Increasing age (OR 1.02, 95% CI 1.004-1.038) and decreasing visual acuity (OR 0.62, 95% CI 0.50-0.78) were associated with an increased likelihood of certification.

Conclusion: A significant number of patients live with certifiable vision impairment but do not access certification. Policy changes in Wales now enable patients with bilateral atrophic AMD to access certification within the primary care setting. Given the unmet need, consideration should be given to primary care certification in the rest of the UK, and in Wales, the potential to expand the scope of conditions.

Introduction: To investigate the perspectives of people accessing a general medical practitioner (GP)-optometry model of collaborative care that was established to increase access to diabetes eye care.

Methods: Qualitative study of patient barriers and facilitators to accessing primary diabetes eye care located in a metropolitan area in Australia. One-on-one interviews were recorded, transcribed and thematically analysed using a determinant framework on patient-centred access to health care.

Results: Twenty-four people with type 2 diabetes, including 15 males and 9 females, who accessed the service between September 2021 and June 2022 agreed to participate. Mean (SD) age of the participants was 52 (12) years and 50% had been diagnosed with diabetes for <2 years. Facilitators to accessing diabetes eye care included a referral from a GP or GP nurse, fee-free consultations, availability of after-hours appointments and short waiting times. Barriers to access included perceived out-of-pocket costs, competing responsibilities and lack of awareness of diabetic retinopathy screening recommendations.

Conclusion: Considering diabetic retinopathy may present asymptomatically, primary health practitioners (optometrists and GPs) are well positioned to raise patient awareness of the importance of routine eye examinations. In Australia, access to routine screening could be facilitated by fee-free eye checks and personalised text message reminders implemented at a health system level.

Purpose: Attention deficit and hyperactivity disorder (ADHD) is a neurodevelopmental condition commonly seen in children and adolescents, characterised by an increase in distractibility or inattention. Several studies have noted a higher rate of visual problems in this group, especially convergence insufficiency (CI), but when using different diagnostic criteria. The aim of this study was to evaluate visual function in ADHD children and non-ADHD controls to compare the different signs for diagnosis of CI.

Method: In this prospective case-control study, a group of children aged 7-17 years, diagnosed with ADHD before the start of pharmacological treatment and matched for age and gender with non-ADHD controls were examined. Visual acuity (VA), objective and subjective refraction, accommodative amplitude and facility, heterophoria, positive and negative fusional vergences (PFV and NFV) and stereopsis were assessed.

Results: Sixty participants (30 ADHD and 30 non-ADHD controls) were evaluated. There was no significant difference between the two groups for VA, refraction and accommodative abilities. There were significant differences in PFV and NFV: PFV break/recovery values for the ADHD and control groups were 18.9/16.2∆ and 26.9/22.1∆, respectively. Respective values for NFV were 15.7/13∆ and 19.3/15.9∆. Using the three signs of receded near point of convergence (NPC), decreased PFV and exophoria 4∆ greater at near than distance, the prevalence of CI was equivalent for the ADHD and controls (p = 0.34) If only two signs were considered for the CI diagnosis, (i.e., receded NPC and decreased PFV), then prevalence was significantly greater for the ADHD group (p < 0.01).

Conclusions: These results show a higher prevalence of binocular vision problems in the ADHD group. This suggests a relationship between vergence problems and ADHD, but the direction of this link remains unclear. Further studies with specific samples may be needed to understand fully the association between binocular vision disorders and ADHD.