Brien Anthony Holden

Characteristics of peripheral refractive errors of myopic and non-myopic Chinese eyes

Interest in peripheral refractive errors has increased as it was hypothesized that peripheral hypermetropia might provide a stimulus for axial elongation (Smith et al., 2005), this study was to determine relative peripheral refractive errors (RPRE) of the eyes of a group of Chinese children and adults. Central and peripheral (20 degrees , 30 degrees , 40 degrees at nasal, temporal, superior and inferior meridians of retina) refractive errors were obtained from cyclopleged eyes of 40 children and 42 adults with a Shin-Nippon auto-refractor. Only right eyes were considered. Central spherical equivalent (M) was used to classify the eyes as Moderate Myopia (MM, -3.00 < M < or = -6.00D), Low Myopia (LM, -0.50 < or = M < or = -3.00D), Emmetropia (E, -0.50<M<+0.50D) and Low Hypermetropia (LH, +0.50<M+2.00D). RPRE was calculated as the difference in M between the central and peripheral positions. The results showed that in both children and adults, horizontally, the RPRE profile for the MM group had a relative hypermetropic shift and in contrast, the profile for LH demonstrated a relative myopic shift. The difference in the profile between the MM and LH group was significant (p<0.05). Also, the RPRE profile for MM group was different between adults and children with adult eyes showing greater amount of hypermetropic shift. Vertically, the RPRE profile of all the refractive error groups showed a myopic shift. Off-axis astigmatism increased and horizontally a shift from with the rule to against the rule astigmatism was observed for all groups. Our observations demonstrated that in Chinese eyes, the myopic group present a hyperopic shift in the periphery, the hypermetropic eye present a myopic shift and the emmetropic eyes present no differences to the fovea, which are similar to those reports in Caucasian eyes. The variations in the RPRE between various refractive error groups can be explained on the basis of eye shape.

Effects of Long-Wavelength Lighting on Refractive Development in Infant Rhesus Monkeys

PURPOSEnDifferences in the spectral composition of lighting between indoor and outdoor scenes may contribute to the higher prevalence of myopia in children who spend low amounts of time outdoors. Our goal was to determine whether environments dominated by long-wavelength light promote the development of myopia.nnnMETHODSnBeginning at 25 ± 2 days of age, infant monkeys were reared with long-wavelength-pass (red) filters in front of one (MRL, n = 6) or both eyes (BRL, n = 7). The filters were worn continuously until 146 ± 7 days of age. Refractive development, corneal power, and vitreous chamber depth were assessed by retinoscopy, keratometry, and ultrasonography, respectively. Control data were obtained from 6 monkeys reared with binocular neutral density (ND) filters and 33 normal monkeys reared with unrestricted vision under typical indoor lighting.nnnRESULTSnAt the end of the filter-rearing period, the median refractive error for the BRL monkeys (+4.25 diopters [D]) was significantly more hyperopic than that for the ND (+2.22 D; P = 0.003) and normal monkeys (+2.38 D; P = 0.0001). Similarly, the MRL monkeys exhibited hyperopic anisometropias that were larger than those in normal monkeys (+1.70 ± 1.55 vs. -0.013 ± 0.33 D, P < 0.0001). The relative hyperopia in the treated eyes was associated with shorter vitreous chambers. Following filter removal, the filter-reared monkeys recovered from the induced hyperopic errors.nnnCONCLUSIONSnThe observed hyperopic shifts indicate that emmetropization does not necessarily target the focal plane that maximizes luminance contrast and that reducing potential chromatic cues can interfere with emmetropization. There was no evidence that environments dominated by long wavelengths necessarily promote myopia development.

Comparison of patient satisfaction with services of vision centers in rural areas of Andhra Pradesh, India.

Aim: To compare the satisfaction of patients with the services of Vision Center services (primary eye care) in large village (s) and small village (s) in rural settings in Andhra Pradesh state, India. Materials and Methods: We have administered standard questionnaires to randomly selected patients to assess patient satisfaction when assessing Vision Center Services. We used the Chi-square (P <0.05) to explore differences in satisfaction of patients with Vision Center services located in the large village (s) and small village (s) rural settings. Results: Vision Center patients at the large village (s) expressed higher levels of satisfaction (median 78%) than patients treated at the Vision Center at small village (s) (median 69%). The difference was statistically significant (Chi square P value ranging from <0.001 to 0.03) for all the items except two – ‘easy to identify vision center location’ and ‘spectacles dispensing time’ as compared to other (privately run optometry) facilities (Chi square P value=0.498 and 0.993 respectively). The location of the Vision Center, convenience of journey, ophthalmic technician’s behavior with patients, are some of the most important factors that determined the patient perception about Vision Center services. Conclusion: The overall satisfaction levels of the Vision Center experience at 78% and 69% were good. However, continual improvement is to be made in service time, staff performance, cost and quality of vision care, especially at more remote primary eye Care Centers.

The Effects of Simultaneous Dual Focus Lenses on Refractive Development in Infant Monkeys

PURPOSEnWe investigated the effects of two simultaneously imposed, competing focal planes on refractive development in monkeys.nnnMETHODSnStarting at 3 weeks of age and continuing until 150 ± 4 days of age, rhesus monkeys were reared with binocular dual-focus spectacle lenses. The treatment lenses had central 2-mm zones of zero power and concentric annular zones with alternating powers of +3.0 diopter [D] and plano (pL or 0 D) (n = 7; +3D/pL) or -3.0 D and plano (n = 7; -3D/pL). Retinoscopy, keratometry, and A-scan ultrasonography were performed every 2 weeks throughout the treatment period. For comparison purposes data were obtained from monkeys reared with full field (FF) +3.0 (n = 4) or -3.0 D (n = 5) lenses over both eyes and 33 control animals reared with unrestricted vision.nnnRESULTSnThe +3 D/pL lenses slowed eye growth resulting in hyperopic refractive errors that were similar to those produced by FF+3 D lenses (+3 D/pL = +5.25 D, FF +3 D = +4.63 D; P = 0.32), but significantly more hyperopic than those observed in control monkeys (+2.50 D, P = 0.0001). One -3 D/pL monkey developed compensating axial myopia; however, in the other -3 D/pL monkeys refractive development was dominated by the zero-powered portions of the treatment lenses. The refractive errors for the -3 D/pL monkeys were more hyperopic than those in the FF -3 D monkeys (-3 D/pL = +3.13 D, FF -3D = -1.69 D; P = 0.01), but similar to those in control animals (P = 0.15).nnnCONCLUSIONSnIn the monkeys treated with dual-focus lenses, refractive development was dominated by the more anterior (i.e., relatively myopic) image plane. The results indicate that imposing relative myopic defocus over a large proportion of the retina is an effective means for slowing ocular growth.

An Estimate of Patient Costs and Benefits of the New Primary Eye Care Model Utilization Through Vision Centers in Andhra Pradesh, India

Little or no work has been carried out in developing countries on costs to patients and patient benefits in accessing primary eye care services. The purpose of this study was to assess the indirect, direct, and overall costs of patients accessing vision care at vision center services (New Primary Eyecare Approach) as compared with the nearest private clinic. The authors used a standardized questionnaire and a paired sample t test to check the significance of difference of costs. They considered a P value of <.05 as significant in this study. The total costs were significantly lower for patients who accessed the vision centers compared with the costs these patients may have incurred if they had sought services from the nearest town-based clinic (mean in Indian rupees [INR] of 178.4 ± 48.3, standard error of the mean = 4.2, and INR 366.2 ± 48.2, standard error of the mean = 4.2, respectively, t test P value < .001). vision centers, besides providing quality eye care services, offer substantial cost savings to rural populations compared with town-based optical clinics.

Restoring Accommodation: Surgical Technique and Preliminary Evaluation in Rabbits

Purpose. To evaluate an innovative surgical technique for phaco-ersatz, a cataract surgery designed to restore accommodation. Techniques for very small capsulorhexis as well as the refilling procedure were developed. This study evaluates the feasibility and reproducibility of the surgical technique. Methods. The right eye of 8 NZW rabbits (≈ 2 Kg) were operated following the ARVO Statements for the Use of Animals in Ophthalmic and Vision Research. The surgery is begun by making a small peripheral capsulorhexis of about 1 mm using. The lens content is then removed. The lens is then refilled with a novel in situ polymerizable gel and the corneal incision is closed using one 10/0 Nylon interrupted stitch. Results. The capsulorhexis technique was succesfully performed and reproducible in all animals. The average size of the capsulorhexis opening was 1. 2 mm (±0.14). Lens material removal and refilling of the capsular bag with an in situ polymerizable material was also performed in each trial study. Conclusion. This surgical technique seemed feasible and reproducible.