Assessment of the effects of myopic and hyperopic anisometropia on choroidal vascular structure in children using SS-OCTA.

OBJECTIVE: To compare large- and medium-sized choroidal vascularity and the choriocapillaris (CC) flow area in children with different refractive errors using swept-source optical coherence tomography angiography (SS-OCTA). METHODS: Forty-two anisometropic children were enrolled and divided into hyperopic anisometropia (HA) and myopic anisometropia (MA) groups. SS-OCTA was performed to analyse choroidal vascularity. Mean choroidal thickness (CT), choroidal vascularity volume (CVV), choroidal vascularity index (CVI) and CC flow area were compared between the two eyes. The inter-ocular differences between the two groups were also determined. RESULTS: Mean CT and CVV were highest in eyes with shorter axial lengths in both refractive groups, and the difference between the two eyes was positively correlated with the difference in axial length at the foveal region. Significant differences in the CVI in the MA group were only found in the parafoveal region. Inter-ocular differences in the CC were significantly reduced in eyes with longer axial lengths in the foveal and parafoveal regions of the HA and MA groups, respectively. Comparing inter-ocular differences, CC was significantly greater in the parafoveal region of the MA group than the HA group. CONCLUSIONS: All layers of choroidal vasculature were thinner in eyes with longer axial lengths in all groups. The inter-ocular CC difference was greater in the MA than in the HA group, with similar differences in axial length. This suggests that both medium-to-large choroidal vascular and choroidal capillaries may play a role in myopia development.

Assessment of the ciliary muscle and scleral anterior thickness in high myopia by optical coherence tomography.

PURPOSE: To assess ciliary muscle (CM) and anterior scleral thickness (AST) dimensions in vivo in high myopia using swept-source optical coherence tomography (SS-OCT) and to compare with emmetropic and hyperopic subjects. METHODS: Cross-sectional study that included 34 high myopic patients (≥ -6 diopters [D]), 90 emmetropes (-1 to +1 D) and 38 hyperopic patients (≥ +3.5 D). CM thickness (CMT) and AST were measured in the temporal and nasal quadrants at 1, 2, and 3 mm from the scleral spur using SS-OCT. In addition, the length of the CM (CML) was evaluated. RESULTS: The dimensions of the CML and the CMT at any of their measurement points were greater in high myopes and emmetropes than in hyperopes, both in the nasal and temporal quadrants (P < .001). However, there were no differences between high myopes and emmetropes for any of the parameters (P ≥ .076) except for the CMT at 3 mm in the temporal quadrant (P < .001). There were no differences in the AST between high myopes, emmetropes and hyperopes, in any of the measurement points or quadrants studied (P > .05). CONCLUSIONS: The SS-OCT allows to measure the CM in vivo, not observing differences in its dimensions between high myopes and emmetropes, but they were smaller in hyperopes. In the measurement of the anterior sclera, no differences were observed between the three groups analyzed according to refraction.

The prevalence and causes of pediatric uncorrected refractive error: Pooled data from population studies for Global Burden of Disease (GBD) sub-regions.

BACKGROUND: There are limited systematic reviews on the prevalence of uncorrected refractive errors in children. We aimed to summarize the prevalence and causes of pediatric uncorrected refractive error (URE) from studies in the Global Burden of Disease (GBD) sub-regions. METHODS: The pooled analysis used the individual participant data (ages less than 20 years old) from population-based studies around the world by regions. URE was defined as presenting VA < 6/18 and improving to ≥ 6/18 or ≥1 line on using a pinhole in either eye, with main causes of myopia, hyperopia or astigmatism. Each study provided data on any URE, myopia, hyperopia or astigmatism by age, gender, and ethnicity. Prevalence rates were directly age and gender standardized to the 2020 world population with all age groups. Estimates were calculated by study and sub-regions after pooling. Summary estimates included studies in which URE was assessed from a pinhole-corrected refraction in the better eye. RESULTS: The combined pooled data contained 302,513,219 patients including 8 963 URE cases individuals from 57 studies. Prevalence varied by age and GBD sub-regions and differed by gender. The age- and region-standardized prevalence of URE was 3.41 per 1000 (CI, 1.53~7.62) in Western Pacific region (12 studies), 2.26 per 1000 (CI, 0.85~6.01) in South-East Asia region (14 studies), 5.85 per 1000 (CI, 3.75~9.13) in Americans (11 studies) and 4.40 per 1000 (CI, 3.0~6.45) in Eastern Mediterranean region (13 studies). On the basis of these data, myopia was the first-leading cause in female children with 12~17 age group, with the prevalence rate 18.2 per 1000 (CI, 11.52~23.61). Astigmatism was detected in 27.2 per 1000 male children with 6~11 age group (CI: 19.12-30.68). CONCLUSIONS: Prevalence of URE available data within these sub-regions are widely disparate. Myopia and astigmatism in young age children continue as the leading cause of URE worldwide. Providing appropriate refractive correction to those individuals whose vision can be improved is an important public health endeavor with implications for safety and quality of life.

Objective assessment of corneal backscattered light in myopic, hyperopic, and emmetropic children.

BACKGROUND: To determine the corneal densitometry(CD) values by using Scheimpflug imaging in myopic and hyperopic children and to compare the results with emmetropic children. METHODS: The CD measurements of the subject were obtained with Scheimpflug tomography. The values were automatically measured in standardized grayscale units over an area 12mm in diameter, which was subdivided into 4 annular concentric zones(0-2mm, 2-6mm, 6-10mm, 10-12mm) and 3 corneal depths(anterior layer: anterior 120µm; central layer: from 120µm to the last 60µm; posterior layer: last 60µm). In addition, we evaluated the correlation between spherical equivalence and anterior corneal morphological parameters and the CD values. RESULTS: A total of 211 participants were included in this prospective cross-sectional study. The eyes were divided into three groups related to their spherical equivalent(SE) refractive error values as follows: 88(41.7%) hyperopic eyes, 62(29.4%) myopic eyes, and 61(28.9%) emmetropic control eyes. The hyperopic eyes were found to have lower corneal densitometry values in 4 annular zones and the total 0-12 diameter of all layers except the central layer. However, only the 6-10mm annular zone of the central and posterior layers of the myopic eyes had lower corneal densitometry values than emmetropic eyes. There was also a significant correlation between spherical equivalent and corneal densitometry values in the anterior layer(0-2mm, 2-6mm zones), central layer(0-2mm, 10-12mm zones), posterior layer(6-10mm, 10-12mm zones, and the total 0-12mm diameter), and total corneal thickness(0-2mm zone) of the hyperopic eyes. CONCLUSIONS: Backward scattering of light was lower in hyperopic eyes and this could indicate better visual quality.

Socio-economic differences in accessing NHS spectacles amongst children with differing refractive errors living in Scotland.

BACKGROUND/OBJECTIVES: Adults living in more deprived areas are less likely to attend an eye examination, resulting in greater visual impairment from undiagnosed eye disease and a widening of health inequalities. It is unknown if the introduction of free NHS eye examinations and help with spectacle costs has benefited children in Scotland. This study aimed to explore factors associated with accessing NHS spectacles including level of deprivation, refractive error, urbanity and age. SUBJECTS/METHODS: NHS-financed General Ophthalmic Services (GOS) 3 supplement the cost of spectacles for children under 16 years. Administrative data on the spectacle refraction dispensed were obtained from Information Services Division (ISD) for mainland Scotland, 2018, and categorised by: Emmetropes/low hyperopes (reference group), myopes and moderate/high hyperopes. Data were linked to the Scottish Index of Multiple Deprivation (SIMD) quintile. RESULTS: Data included 108, 043 GOS 3 claims. Greater deprivation was associated with greater GOS 3 claims p = 0.041. This was most evident in emmetropic/low hyperopic children and in moderate/high hyperopic children. GOS 3 claims in the myopes group increased with age across all SIMD and decreased with age in the moderate/high hyperope group (all p < 0.001). GOS 3 claims were not associated with urbanity for all Health Boards (p = 0.13). CONCLUSIONS: Children in areas of greater deprivation and in more rural areas are not disadvantaged in accessing NHS spectacles. This did not vary by refractive error group. This suggests that health policy in Scotland is accessible to those from all deprivation levels and refractive errors.

Assessment of Refractive Outcomes of Femtosecond-assisted Laser in Situ Keratomileusis (LASIK) for Hyperopia.

OBJECTIVE: To determine the effect of refractive treatment in terms of safety, efficacy, stability, accuracy, and predictability with Wavefront Optimized Laser-assisted in situ keratomileusis (LASIK) on hyperopia. STUDY DESIGN: Descriptive, analytical study. PLACE AND DURATION OF STUDY: Armed Forces Institute of Ophthalmology, National University of Medical Sciences, Rawalpindi, Pakistan from August 2013 to June 2018.  Methodology: Participants were selected after detailed history, careful ocular examination and meticulous relevant assessment on refractive scans. Preoperative measurements were recorded. Refractive strategy was designed, considering individual requirements for each patient. Postoperative readings were taken at 1 day, 1 week, 1, 3, 6 and 12 months. RESULTS: A total of 54 patients participated with mean age of 28.07 + 8.13 years. Out of the 54 patients, 33 (61%) were males and 21 (39%) were females. Uncorrected distance visual acuity (UDVA) and Spherical equivalent (SEQ), which is algebraic sum of sphere and half of cylinder, were recorded pre- and postoperatively. These parameters were changed significantly at 12 months (p <0.001). SEQ reduced from 2.146 + 2.027 to 0.079 ± 0.269 Diopter (D) (p <0.001). UDVA improved from 0.672 ± 0.270 (20/93) to 0.153 ± 0.182 (20/28) (p <0.001). A total of 48 (out of 54) patients had uncorrected vision better than 20/40; and 49 patients showed either same or gain of Snellen lines when pre- and postoperative corrected distance visual acuity (CDVA) was compared. Two patients showed loss of two or more lines. All the patients had postoperative SEQ within + 1.0 D range. CONCLUSION: LASIK, performed to correct hyperopia, demonstrated satisfactory outcomes in terms of safety, efficacy, stability, accuracy, and predictability. LASIK is an effective treatment option for moderate (<6 D) hyperopia. Key Words: LASIK, Refractive surgery, Hyperopia, Spherical equivalent, Uncorrected distance visual acuity.

Long-term assessment of visual and refractive outcomes of laser in situ keratomileusis for hyperopia using the AMARIS® 750S Excimer laser.

PURPOSE: To evaluate the long-term efficacy and safety of hyperopic laser in situ keratomileusis (LASIK) using the AMARIS® 750S (Schwind, Eye-tech-solutions, GmbH) excimer laser. METHODS: The medical records of one hundred eleven eyes of 62 patients who underwent LASIK for hyperopia using the AMARIS® 750S excimer laser were reviewed retrospectively. Patients were divided into three groups based on preoperative spherical equivalent (SE) refraction: low hyperopia (less than +2.50 diopters [D]), moderate hyperopia (+2.75D to +4.00D), and high hyperopia (over +4.00D). Uncorrected and best corrected visual acuity (BCVA), long-term stability of refraction, and complications were evaluated. RESULTS: Of the entire sample, the mean preoperative SE was +3.64D±1.22D. The mean age was 37.4±11.2 years (20-59). The mean follow-up for all eyes was 51 months. At the last visit, the mean SE was +0.85D±0.34D (SD) in the low hyperopia group, +1.09D±0.43D in the moderate hyperopia group, and +1.63D±0.47D in the high hyperopia group. (+1.15D±0.49D overall). Preoperative uncorrected visual acuity (UCVA) was 0.52±0.34 logMAR and increased to 0.18±0.15 logMAR at 4 years follow-up (P<0.01). There was no statistically significant difference between preoperative and postoperative BCVA. The UCVA was 0.30 logMAR or better in 100% of eyes in the low hyperopia group, 93.7% in the moderate hyperopia group, and 69.9% in the high hyperopia group (%89.2 overall). CONCLUSIONS: LASIK is safe and effective for correcting hyperopia in the short term; however, the efficacy of the procedure is limited in the patients with high hyperopia and longer follow-up.

Comparing wavefront-optimized, wavefront-guided and topography-guided laser vision correction: clinical outcomes using an objective decision tree.

PURPOSE OF REVIEW: This review is intended to update and educate the reader on the currently available options for laser vision correction, more specifically, laser-assisted in-situ keratomileusis (LASIK). In addition, some related clinical outcomes data from over 1000 cases performed over a 1-year are presented to highlight some differences between the various treatment profiles currently available including the rapidity of visual recovery. The cases in question were performed on the basis of a decision tree to segregate patients on the basis of anatomical, topographic and aberrometry findings; the decision tree was formulated based on the data available in some of the reviewed articles. RECENT FINDINGS: Numerous recent studies reported in the literature provide data related to the risks and benefits of LASIK; alternatives to a laser refractive procedure are also discussed. The results from these studies have been used to prepare a decision tree to assist the surgeon in choosing the best option for the patient based on the data from several standard preoperative diagnostic tests. SUMMARY: The data presented here should aid surgeons in understanding the effects of currently available LASIK treatment profiles. Surgeons should also be able to appreciate how the findings were used to create a decision tree to help choose the most appropriate treatment profile for patients. Finally, the retrospective evaluation of clinical outcomes based on the decision tree should provide surgeons with a realistic expectation for their own outcomes should they adopt such a decision tree in their own practice.

Results of a pediatric vision screening program in western South Dakota.

BACKGROUND: South Dakota is one of eight states that do not require any vision screening for children. This study describes the results of the first children's vision screening program in the state. METHODS: Children ages 6 months to 12 years were screened using the SPOT photoscreener by lay volunteers as part of the Northern Plains Eye Foundation's Western South Dakota Children's Vision Screening Initiative (CVSI). Referral criteria were based on the recommendations of the manufacturer. Data was stratified by age group, sex, and percentage of children referred for hyperopia, myopia, astigmatism, anisocoria, anisometropia, and ocular misalignment. The cost benefit of amblyopia treatment in South Dakota was also calculated. RESULTS: Screenings were completed on 4,784 children from August 2012 to May 2014 with 62 excluded due to age. Mean age of the 4,722 (2,373 females) subjects was 6 years 7 months. Overall, the SPOT device referred 563 (11.9 percent) children. There was no significant difference in referral rate based on sex (p = 0.598). Children aged 73-144 months had the highest referral rate (12.2 percent) and children aged 12-30 months had the lowest referral rate (7.9 percent). The suspected reasons for referral based upon the screenings were as follows: 371 (7.9 percent) astigmatism, 24 (0.5 percent) ocular misalignment, 101 (2.1 percent) anisometropia, 135 (2.9 percent) myopia, 36 (0.8 percent) hyperopia, and 16 (0.3 percent) anisocoria. CONCLUSIONS: The SPOT photoscreener yielded an acceptable referral rate of 11.9 percent. This study represents an effective model for pediatric vision screening in South Dakota.

The assessment of anterior and posterior ocular structures in hyperopic anisometropic amblyopia.

BACKGROUND: The aim of this study was to examine the relationship or differences in ocular structures of amblyopic eyes compared to fellow eyes in children and young adults with hyperopic anisometropic amblyopia. MATERIAL/METHODS: Hyperopic participants with anisometropic amblyopia, defined as the presence of best-corrected visual acuity differences of at least 2 Snellen lines and 1.5 diopters between amblyopic and fellow eyes, were studied. Using the IOL Master, Pentacam Scheimpflug imaging and Spectralis optical coherence tomography, the axial length, corneal curvature, and anterior chamber depth (ACD), as well as the thickness of the cornea, peripapillary retinal nerve fiber layer (RNFL), and macula, were compared between children and young adults and between their amblyopic and fellow eyes. RESULTS: In 53 participants with hyperopic anisometropic amblyopia, there were significant differences in the anterior corneal curvature, ACD and axial length between the amblyopic and fellow eyes of all the patients. The mean central macular thickness in the amblyopic eyes was significantly thicker (P=.001) in the group aged 5 to 12 years; however, this was not the case in the group aged 13 to 42 years. There was no significant difference in average RNFL thickness in either group. CONCLUSIONS: We found significantly greater mean central macular thickness in anisometropic amblyopic eyes among participants aged 5 to 12 years, but not among those who were older. Similarly, the interocular differences in axial length parameters seemed to be related to the central macular thickness differences between the amblyopic and fellow eyes in the younger group.

Patient satisfaction and clinical outcomes with laser refractive surgery performed by surgeons in training.

PURPOSE: To evaluate the refractive error quality of life (RQL) improvement, patient satisfaction, and clinical results of laser refractive surgery performed by residents or fellows. SETTING: Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, USA. DESIGN: Case series. METHODS: This study reviewed the clinical results of consecutive refractive surgery cases performed between March 2010 and February 2012 by ophthalmology residents or fellows. One-year postoperative analysis of the RQL and patient satisfaction in a subgroup of patients was completed using the National Eye Institute Refractive Error Correction Quality of Life-42 instrument (NEI RQL-42), and a comparison with NEI published normative data and post-refractive data was performed. RESULTS: Data were obtained from 138 eyes that had laser in situ keratomileusis and 4 eyes that had photorefractive keratectomy. The 1-year postoperative analysis of the RQL and patient satisfaction was completed in 34 patients. After 6 months postoperatively, the mean uncorrected distance visual acuity was 0.01 logMAR (95% confidence interval [CI], -0.012 to 0.023). The mean postoperative residual refractive error spherical equivalent was -0.20 diopter (D) (95% CI, -0.26 to -0.13). No eye lost corrected distance visual acuity. Equivalent or better satisfaction in the RQL was found in all but 1 of the 13 scale scores of the NEI RQL-42 compared with previously published NEI data. CONCLUSIONS: Laser refractive surgery performed by residents and fellows showed high patient satisfaction and an improved RQL 1-year postoperatively. Clinical outcomes validated the safety and efficacy of refractive surgery performed by surgeons in training. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

The bigaussian nature of ocular biometry.

PURPOSE: To study how the leptokurtic shape of the refractive distribution can be derived from ocular biometry by means of a multivariate Gaussian model. METHODS: Autorefraction and optical biometry data (Scheimpflug and partial coherence interferometry) were obtained for 1136 right eyes of healthy white subjects recruited by various European ophthalmological centers participating in Project Gullstrand. These biometric data were fitted with linear combinations of multivariate Gaussians to create a Monte Carlo simulation of the biometry, from which the corresponding refraction was calculated. These simulated data were then compared with the original data by histogram analysis. RESULTS: The distribution of the ocular refraction more closely resembled a bigaussian than a single Gaussian function (F test, p < 0.001). This also applied to the axial length, which caused the combined biometry data to be better represented by a linear combination of two multivariate Gaussians rather than by a single one (F test, p < 0.001). Corneal curvature, anterior chamber depth, and lens power, on the other hand, displayed a normal distribution. All distributions were found to gradually change with age. The statistical descriptors of these two subgroups were compared and found to differ significantly in average and SD for the refraction, axial length, and anterior chamber depth. All distributions were also found to change significantly with age. CONCLUSIONS: The bigaussian model provides a more accurate description of the data from the original refractive distribution and suggests that the general population may be composed of two separate subgroups with different biometric properties.

Femtosecond lasers for LASIK flap creation: a report by the American Academy of Ophthalmology.

OBJECTIVE: To review the published literature to assess the safety, efficacy, and predictability of femtosecond lasers for the creation of corneal flaps for LASIK; to assess the reported outcomes of LASIK when femtosecond lasers are used to create corneal flaps; and to compare the differences in outcomes between femtosecond lasers and mechanical microkeratomes. METHODS: Literature searches of the PubMed and Cochrane Library databases were last conducted on October 12, 2011, without language or date limitations. The searches retrieved a total of 636 references. Of these, panel members selected 58 articles that they considered to be of high or medium clinical relevance, and the panel methodologist rated each article according to the strength of evidence. Four studies were rated as level I evidence, 14 studies were rated as level II evidence, and the remaining studies were rated as level III evidence. RESULTS: The majority of published studies evaluated a single laser platform. Flap reproducibility varied by device and the generation of the device. Standard deviations in flap thicknesses ranged from 4 to 18.4 µm. Visual acuities and complications reported with LASIK flaps created using femtosecond lasers are within Food and Drug Administration safety and efficacy limits. Of all complications, diffuse lamellar keratitis is the most common after surgery but is generally mild and self-limited. Corneal sensation was reported to normalize by 1 year after surgery. Unique complications of femtosecond lasers included transient light-sensitivity syndrome, rainbow glare, opaque bubble layer, epithelial breakthrough of gas bubbles, and gas bubbles within the anterior chamber. CONCLUSIONS: Available evidence (levels I and II) indicates that femtosecond lasers are efficacious devices for creating LASIK flaps, with accompanying good visual results. Overall, femtosecond lasers were found to be as good as or better than mechanical microkeratomes for creating LASIK flaps. There are unique complications that can occur with femtosecond lasers, and long-term follow-up is needed to evaluate the technology fully.

Amblyopia and refractive errors among school-aged children with low socioeconomic status in southeastern Turkey.

PURPOSE: To investigate the prevalence of refractive errors and other eye diseases, incidence and types of amblyopia in school-aged children, and their relation to gender, age, parental education, and socioeconomic factors. METHODS: A total of 21,062 children 6 to 14 years old were screened. The examination included visual acuity measurements and ocular motility evaluation. Autorefraction under cycloplegia and examination of the external eye, anterior segment, media, and fundus were performed. RESULTS: There were 11,118 females and 9,944 males. The average age was 10.56 ± 3.59 years. When all of the children were evaluated, 3.2% had myopia and 5.9% had hyperopia. Astigmatism 0.50 D or greater was present in 14.3% of children. Myopia was associated with older age, female gender, and higher parental education. Hyperopia was inversely proportional with older age. Spectacles were needed in 4,476 (22.7%) children with refractive errors, and 10.6% of children were unaware of their spectacle needs. Amblyopia was detected in 2.6% of all children. The most common causes of amblyopia were anisometropia (1.2%) and strabismus (0.9%). CONCLUSION: Visual impairment is a common disorder in school-aged children. Eye health screening programs are beneficial in early detection and proper treatment of refractive errors.

Theoretical analysis for spherical aberration induction with low-order correction in refractive surgery.

A theoretical foundation for the analysis of ocular aberration correction is developed. It enables a comparative study for two different refractive surgical approaches, namely, the conventional and the Q-preserved treatment modalities. A refractive surgical factor is identified that leads to a simple cubic function for the postoperative asphericity factor for the conventional treatment. A formulation is developed that paves the way for the calculation of the induction of spherical aberration for low-order aberration correction in refractive surgery. Opposite to the general belief, the Munnerlyn shape makes myopic LASIK more prolate, not oblate. A Monte Carlo simulation was conducted for 1000 eyes for these two refractive surgical modalities. It was found that, although the postoperative spherical aberration is similar for these surgical modalities, for the induction of spherical aberration from the ablation target shape, the conventional modality appears to be slightly more predictable.

Validity of noncycloplegic refraction in the assessment of refractive errors: the Tehran Eye Study.

PURPOSE: To determine the sensitivity and specificity of noncycloplegic autorefraction for determining refractive status compared to cycloplegic autorefraction. METHODS: The target population was noninstitutionalized citizens of all ages, residing in Tehran in 2002, selected through stratified cluster sampling. From 6497 eligible residents, 70.3% participated in the study, from August to November 2002. Here, we report data on 3501 people over the age of 5 years who had autorefraction with and without cycloplegia (two drops of cyclopentolate 1.0% 5 min apart, with autorefraction 25 min after the second drop). RESULTS: Overall, the sensitivity of noncycloplegic autorefraction for myopia was 99%, but the specificity was only 80.4%. In contrast, the sensitivity for hyperopia was only 47.9%, but the specificity was 99.4%. At all ages, noncycloplegic autorefraction overestimated myopia and underestimated hyperopia. Overestimation of myopia was highest in the 21-30 and 31-40 year groups. Underestimation of hyperopia was high up to the age of 50 (20-40%), but decreased with age, to about 8% after the age of 50, down to almost 0% after 70. The difference in mean spherical equivalent with and without cycloplegia fell from 0.71 dioptres (D) in the 5-10 age group to 0.14D in those over 70. CONCLUSION: Use of noncycloplegic autorefraction in epidemiological studies leads to considerable errors relative to cycloplegic measurements, except in those over 50-60. The difference between cycloplegic and noncycloplegic measurements varies with age and cycloplegic refractive category, and there is considerable individual variation, ruling out adjusting noncycloplegic measurements to obtain accurate cycloplegic refractions.

Reproducibility of straylight measurement by C-Quant for assessment of retinal straylight using the compensation comparison method.

BACKGROUND: Straylight gives the appearance of a veil of light thrown over a person's retinal image when there is a strong light source present. We examined the reproducibility of the measurements by C-Quant, and assessed its correlation to characteristics of the eye and subjects' age. PARTICIPANTS AND METHODS: Five repeated straylight measurements were taken using the dominant eye of 45 healthy subjects (age 21-59) with a BCVA of 20/20: 14 emmetropic, 16 myopic, eight hyperopic and seven with astigmatism. We assessed the extent of reproducibility of straylight measures using the intraclass correlation coefficient. RESULTS: The mean straylight value of all measurements was 1.01 (SD 0.23, median 0.97, interquartile range 0.85-1.1). Per 10 years of age, straylight increased in average by 0.10 (95%CI 0.04 to 0.16, p < 0.01]. We found no independent association of refraction (range -5.25 dpt to +2 dpt) on straylight values (0.001; 95%CI -0.022 to 0.024, p = 0.92). Compared to emmetropic subjects, myopia reduced straylight (-.011; -0.024 to 0.02, p = 0.11), whereas higher straylight values (0.09; -0.01 to 0.20, p = 0.09) were observed in subjects with blue irises as compared to dark-colored irises when correcting for age. The intraclass correlation coefficient (ICC) of repeated measurements was 0.83 (95%CI 0.76 to 0.90). CONCLUSIONS: Our study showed that straylight measurements with the C-Quant had a high reproducibility, i.e. a lack of large intra-observer variability, making it appropriate to be applied in long-term follow-up studies assessing the long-term effect of surgical procedures on the quality of vision.

Refractive error in Nigerian adults: prevalence, type, and spectacle coverage.

PURPOSE: To provide data on prevalence and types of refractive error and the spectacle-wearing rate among adults in Nigeria and the degree to which the need for distance correction could be met by off-the-shelf spectacles. METHODS: Multistage, stratified, cluster random sampling with probability proportional to size was used to identify a nationally representative sample of 15,027 persons aged ≥40 years. Distance vision was measured using a reduced logMAR tumbling-E chart. All participants underwent autorefraction, and those with presenting acuity of <6/12 in one or both eyes had their corrected acuity measured and underwent detailed clinical examination to determine the cause. RESULTS: Included in the survey were 13,599 (89.9%) of the 15,122 persons aged ≥40 years who were enumerated. Uncorrected refractive error was responsible for 77.9% of mild visual impairment (<6/12-6/18), 57.1% of moderate visual impairment (<6/18-6/60), 11.3% of severe visual impairment (<6/60-3/60), and 1.4% of blindness (<3/60). The crude prevalence of myopia (≤0.5 D) and high myopia (≤5.0 D) were 16.2% and 2.1%, respectively. Spectacles could improve the vision of 1279 (9.4%) and 882 (6.5%) participants at the 6/12 and 6/18 level, respectively, but only 3.4% and 4.4% of these individuals wore spectacles to the examination site. Approximately 2,140,000 adults in Nigeria would benefit from spectacles that improved their vision from <6/12 to ≥6/12. More than a third of the need could be met by low-cost, off-the-shelf spectacles. CONCLUSIONS: Uncorrected refractive errors are an important cause of visual impairment in Nigeria, and services must be dramatically improved to meet the need.

Corneal flap assessment with Rondo microkeratome in laser in situ keratomileusis.

PURPOSE: To assess the accuracy of flap thickness in laser in situ keratomileusis (LASIK) with Rondo, Wavelight AG microkeratome and to examine factors that can influence flap thickness (FT). SETTING: The study took place at the Laser & Ophthalmos Eye Clinic, Thessaloniki, Greece. MATERIAL AND METHODS: Three hundred and sixty eyes from 180 patients underwent LASIK with Rondo microkeratome. Three surgeons (A, B and C) performed all surgeries with no previous experience of Rondo microkeratome. All patients were treated with the 130 µm plate. Central corneal thickness (CCT) and stromal bed thickness were measured by Scheimpflug and ultrasound pachymetry. Right eye (OD) was treated first. RESULTS: Mean FT for OD: 120 ± 19 µm (range 69-158 µm); for left eye (OS): 106 ± 17 µm (range 70-147 µm). Flaps in OD were significantly thicker than in OS (p < 0.001). FT was significantly correlated to the keratometric reading (K): r = 0.121; p = 0.02. No correlation was found between FT and CCT or between FT and the attempted refractive correction (SE) (p > 0.14). Mean FT was significantly lower than the manufacturer's 130 µm specification (Mean FT = 113 ± 19 µm; p < 0.001). FT between surgeons A, B and C was significantly different (analysis of variance between surgeons; p < 0.001). Scheimpflug and ultrasound CCT measurements were significantly correlated (r = 0.921; p < 0.001) with ultrasound measuring an average 4.5 µm higher than Scheimpflug (CCT (Oculyzer) = 553.96 ± 27 µm; CCT (Ultrasound) = 558.45 ± 28 µm). Mean flap diameter was 9.2 ± 0.2 mm. CONCLUSIONS: FT with Rondo microkeratome was significantly influenced by the mean preoperative K reading. First treated eye was significantly thicker than the fellow left eye, while both were significantly lower than the recommended 130 µm thickness. Gaining basic experience of Rondo microkeratome required an average of 90 flaps/surgeon.

Ophthalmic assessment of children with down syndrome: is England doing its bit?

INTRODUCTION: Patients with Down syndrome have characteristic features including ocular manifestations. Guidelines exist for ophthalmic surveillance of people with Down syndrome, but locally (North Staffordshire) there is no formal program in place. METHODS: Hospital records were used to detect children with Down syndrome. Data were extracted retrospectively to determine which children had been seen by ophthalmic services, the mode of assessment used, and the frequency of ophthalmic disorders. RESULTS: Of the 96 children with Down syndrome, 38% received no ophthalmic assessment. Of those seen, the mean age at first appointment was nearly 3 years, with a number of children being more than 5 years old. Most children (96%) had at least one ophthalmic abnormality, the commonest being hyperopia. Requested follow-up was routinely exceeded by almost a year with 19% of children receiving no follow-up. DISCUSSION: Ocular disorders are common in the two thirds of children who are currently seen by ophthalmic services. Locally, we are falling short of the targets set by the 2006 recommendations for basic medical care of people with Down syndrome. A screening program might have a beneficial impact on the vision of children with Down syndrome.