Diopter Cylinder Research Articles

Two millimeter micro incision lenticule extraction surgery with minimal invasion: a preliminary clinical report

To report the clinical results of micro incision lenticule extraction (MILE) to correct myopia or myopia with astigmatism, and enlighten its viability and mechanism. Prospective case-control study. All patients enrolled were treated by the VisuMax femtosecond laser system to correct refractive errors. Sixty-one patients underwent MILE with an incision of 2 mm. Another 53 patients underwent small incision lenticule extraction (SMILE) with a 3-5 mm incision as the control group. All patients took measurements of uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refractive power and intraocular pressure, slit-lamp microscopy, and corneal topography preoperatively and at 1 day, 1 week, 1 month, 6 months postoperatively. The visual acuity was presented as median. To compare the visual acuity and astigmatism between the MILE group and the SMILE group, as well as before surgery and at each time point after surgery, non-parametric tests were applied in this study. The repeated measures analysis of variance was used to compare the differences between these two surgeries and between pre- and post-operation in diopters and morphological parameters. The paired-sample t test was used to compare the diopters and morphological parameters at each time point postoperatively and preoperatively. The independent-sample t test was applied to compare the basic characteristics preoperatively and the diopters, morphological parameters at each time point between these two groups. Forty-one eyes (24 patients) in the MILE group and fifty-one eyes (29 patients) in the SMILE group had complete follow-up data. Before surgery and at 1 day, 1 week, 1 month, 6 months after surgery, the spherical diopters in the MILE group were (-5.09 ± 1.04), (0.12 ± 0.32), (0.11 ± 0.29), (0.02 ± 0.33) and (0.02 ± 0.23) D; the cylinder diopters were (-0.90 ± 0.83), (-0.25 ± 0.27), (-0.23 ± 0.30), (-0.20 ± 0.25) and (-0.16 ± 0.21) D. In the SMILE group, the spherical diopters were (-5.37 ± 1.26), (-0.04 ± 0.49), (0.12 ± 0.38), (0.10 ± 0.34) and (0.02 ± 0.33) D; the cylinder diopters were (-0.76 ± 0.65), (-0.22 ± 0.26), (-0.25 ± 0.30), (-0.26 ± 0.29) and (-0.21 ± 0.28) D. No significant difference was found between the two groups (F = 1.042, 0.941, 0.018; P = 0.310, 0.335, 0.894). In the vector analysis of astigmatism, at 1 month and 6 months after surgery, the values on Y axis were -0.06 ± 0.11 and -0.04 ± 0.10 in the MILE group, smaller than -0.14 ± 0.18 and -0.11 ± 0.16 in the SMILE group (Z = -2.076, -2.149; P = 0.038, 0.032). All full-correction patients had UCVA of 20/20 or better, and no BCVA decreased after 6 month follow-up postoperatively. Refractive stability was achieved within 1 month postoperatively, and less volatility appeared in the MILE group than the SMILE group. Before surgery and at 1 day, 1 week, 1 month, 6 months after surgery, no significant difference in the index of surface variance (ISV) and the index of vertical asymmetry (IVA) was found between the MILE group and the SMILE group (F = 0.902, 0.744; P = 0.345, 0.391), whereas the values of ISV and IVA were smaller in the MILE group than the SMILE group at each time point after surgery, and the D-value between the two groups increased with time. Six cases (9 eyes) had an opaque bubble layer while femtosecond laser passed in the procedure, 2 eyes had a small tear at the incision edge, 1 eye had local diffuse inflammatory exudates at 1 day postoperatively, and no eye had transient light-sensitivity syndrome, decrease of corneal transparency or infection. MILE surgery (1.5-2.0 mm) is safe, predictable, effective and stable to treat refractive errors. It can reduce astigmatism values on oblique axis and maintain the integrality and stability of the structure of the cornea.

Risk factors for astigmatism in the Vision in Preschoolers Study.

To determine demographic and refractive risk factors for astigmatism in the Vision in Preschoolers Study. Three- to 5-year-old Head Start preschoolers (N = 4040) from five clinical centers underwent comprehensive eye examinations by study-certified optometrists and ophthalmologists, including monocular visual acuity testing, cover testing, and cycloplegic retinoscopy. Astigmatism was defined as the presence of greater than or equal to +1.5 diopters (D) cylinder in either eye, measured with cycloplegic refraction. The associations of risk factors with astigmatism were evaluated using the odds ratio (OR) and its 95% confidence interval (CI) from logistic regression models. Among 4040 Vision in Preschoolers Study participants overrepresenting children with vision disorders, 687 (17%) had astigmatism, and most (83.8%) had with-the-rule astigmatism. In multivariate analyses, African American (OR, 1.65; 95% CI, 1.22 to 2.24), Hispanic (OR, 2.25; 95% CI, 1.62 to 3.12), and Asian (OR, 1.76; 95% CI, 1.06 to 2.93) children were more likely to have astigmatism than non-Hispanic white children, whereas American Indian children were less likely to have astigmatism than Hispanic, African American, and Asian children (p < 0.0001). Refractive error was associated with astigmatism in a nonlinear manner, with an OR of 4.50 (95% CI, 3.00 to 6.76) for myopia (≤-1.0 D in spherical equivalent) and 1.55 (95% CI, 1.29 to 1.86) for hyperopia (≥+2.0 D) when compared with children without refractive error (>-1.0 D, <+2.0 D). There was a trend of an increasing percentage of astigmatism among older children (linear trend p = 0.06). The analysis for risk factors of with-the-rule astigmatism provided similar results. Among Head Start preschoolers, Hispanic, African American, and Asian race as well as myopic and hyperopic refractive error were associated with an increased risk of astigmatism, consistent with findings from the population-based Multi-ethnic Pediatric Eye Disease Study and the Baltimore Pediatric Eye Disease Study. American Indian children had lower risk of astigmatism.

Clinical observation of laser refractive surgery for refractive errors after penetrating eye injuries

Objective To evaluate the clinical efficacy,safety and predictability of laser refractive surgery for refractive errors after penetrating eye injuries.Methods It was a retrospective case series study.Twenty five eyes of 25 cases at the age of 21 to 37 yrs.were studied.They were treated by LASEK & LASIK.The eyes manifested uncorrected visual acuity(UCVA) of 0.05 ～0.3,best corrected visual acuity (BCVA) of 0.6 ～ 1.0,spherical diopter (SD) of + 3.5 D ～-4.0 D,cylinder diopter(CD) of + 5.0 D ～-5.0 D.The ametropia was result of penetrating eye injuries,in which 14 eyes only had corneal scar caused by corneal or corneoscleral perforation,the other 11 eyes combined with cataract extraction and intraocular lens (IOL) implantation at the same time for traumatic cataract.All eyes were followed up for 6 months.The UCVA,BCVA and diopter were examined before surgery and 1 m,3m and 6m postoperatively.Results There were 22 eyes(88.0％),24 eyes(96.0％),25 eyes(100％) got UCVA more than 0.5 at 1m,3m and 6m after surgery,respectively.One month after surgery,the BCVA of 20 eyes (80.0％) reached or surpassed the preoperative one,3 eyes(12.0％) declined one line and 2 eyes (8.0％) declined two lines.Three months after surgery,the BCVA of 22 eyes (88.0％) reached or the surpassed the preoperative one,2 eyes (8.0％) declined one line and 1 eye (4.0％) declined two lines.Six months after surgery,the BCVA of 24 eyes (96.0％) reached or surpassed the preoperative one,only 1 eye (4.0％) declined one line.At 1m,3m and 6m after surgery,the SD within ±0.5D was 84.0％,84.0％,80.0％ respectively,and within ± 1.0D were 100％,100％,96.0％ respectively.The CD within ± 0.5D was 80.0％,80.0％,76.0％,respectively,and within ± 1.0D was 92.0％,96.0％,92.0％ respectively.Conclusion Laser refractive surgery is efficient,safe and predictable for refractive errors caused by penetrating eye injuries.The indications must be selected reasonably and the surgical procedures also needed further investigation. Key words: Surgery,corneal,laser ; Injury, eye,penetrating ; Myopia; Hypermetropia; Astigmatism

Cyclotorsion measurement in laser refractive surgery

The aim of this study was to verify the presence of cyclotorsion in eyes that underwent laser refractive surgery. This was a comparative observational study, which analyzed the medical records of 61 patients (104 eyes) who underwent laser refractive surgery and compared the axis of astigmatism of the sitting and the supine positions. Regarding the gender, 37.5% were male and 62.5% were female. The age ranged from 20 to 54 years old, with the median of 29 years. The lowest degree of astigmatism was -0.75 cylinder diopters (DC) and the highest was -6.50 DC, with a mean of -3.06 ± 1.16 DC. First, the axis of astigmatism of the seated patient was captured by the Schwind's ORK-CAM. In a second moment, inside the operating room, the axis of astigmatism of the patient in supine position was captured by the laser equipment's own camera (Schwind Amaris®), which was then compared with the previous measure. The incyclotorsion was defined by a minus sign (-) and the excyclotorsion, by a plus sign (+). The maximum excyclotorsion was +7.7 and the maximum incyclotorsion was -11.0 degrees. The mean torsion (excyclo or incyclo) was 2.74 (56.7%), with a standard deviation of 2.30 degrees. There was no statistically significant change (p=0.985) in the axis of astigmatism between patients sitting versus supine. There was clinically significant cyclotorsion in 36.5% of the eyes submitted to laser correction.

Very High Fluence Collagen Cross-linking as a Refractive Enhancement of a Regressed Previous Astigmatic Keratotomy

To report a novel application of collagen cross-linking (CXL) in refractive astigmatic enhancement of previously performed astigmatic keratotomy. A 28-year-old woman with prior history of bioptics correction of high myopic astigmatism with femtosecond laser-assisted astigmatic keratotomy followed by topography-guided LASIK showed long-term regression of the astigmatism 4 years later. A novel CXL application was employed in an attempt to reverse the regression of the astigmatic keratotomy. The high fluence CXL intervention resulted in correction of 2 diopters of topographic and refractive cylinder. Uncorrected distance visual acuity changed from 20/50 to 20/20 and refraction from -0.50 -2.00 @ 90 to +0.25 -0.25 @ 90 at the 7-month follow-up. A possible novel application of high fluence CXL with refractive cornea effect is introduced. It may offer rapid and simple rehabilitation and its effect may be tapered.

Profile of Anisometropia and Aniso-Astigmatism in Children: Prevalence and Association with Age, Ocular Biometric Measures, and Refractive Status

We describe the profile and associations of anisometropia and aniso-astigmatism in a population-based sample of children. The Northern Ireland Childhood Errors of Refraction (NICER) study used a stratified random cluster design to recruit a representative sample of children from schools in Northern Ireland. Examinations included cycloplegic (1% cyclopentolate) autorefraction, and measures of axial length, anterior chamber depth, and corneal curvature. χ(2) tests were used to assess variations in the prevalence of anisometropia and aniso-astigmatism by age group, with logistic regression used to compare odds of anisometropia and aniso-astigmatism with refractive status (myopia, emmetropia, hyperopia). The Mann-Whitney U test was used to examine interocular differences in ocular biometry. Data from 661 white children aged 12 to 13 years (50.5% male) and 389 white children aged 6 to 7 years (49.6% male) are presented. The prevalence of anisometropia ≥1 diopters sphere (DS) did not differ statistically significantly between 6- to 7-year-old (8.5%; 95% confidence interval [CI], 3.9-13.1) and 12- to 13-year-old (9.4%; 95% CI, 5.9-12.9) children. The prevalence of aniso-astigmatism ≥1 diopters cylinder (DC) did not vary statistically significantly between 6- to 7-year-old (7.7%; 95% CI, 4.3-11.2) and 12- to 13-year-old (5.6%; 95% CI, 0.5-8.1) children. Anisometropia and aniso-astigmatism were more common in 12- to 13-year-old children with hyperopia ≥+2 DS. Anisometropic eyes had greater axial length asymmetry than nonanisometropic eyes. Aniso-astigmatic eyes were more asymmetric in axial length and corneal astigmatism than eyes without aniso-astigmatism. In this population, there is a high prevalence of axial anisometropia and corneal/axial aniso-astigmatism, associated with hyperopia, but whether these relations are causal is unclear. Further work is required to clarify the developmental mechanism behind these associations.

Secondary toric intraocular lens implantation for post-operative ammetropia and astigmatism after small incision cataract surgery

We report a case of 56-year-old female who had undergone left eye small incision cataract surgery 2 months earlier with history of no visual gain uncorrected after surgery. On examination, she had a superior scleral tunnel incision with 6.5 mm optic poly methyl metha acrylate (PMMA) posterior chamber intraocular lens (IOL) in the bag. Her manifest refraction was -5.0 diopter sphere and -3.0 diopter cylinder (DC) at 180°. Her visual acuity improved from 20/200 to 20/20 after correction. The patient underwent explanation of the PMMA IOL with implantation of 23.5 D Acriol EC-T4 toric IOL through temporal clear corneal incision. Postoperatively, at 6 months, the patient had 20/20 (p) visual acuity uncorrected improving to 20/20 after correction by -0.25DC at 40°. Postoperative ammetropia and high cylindrical power can be simultaneously corrected by placement of the toric IOL.

Astigmatism: Prevalence, Distribution and Determinants in Owerri, Nigeria

Background: Astigmatism impairs focusing ability of the eyes at far and near distances. This causes distortion, blurred vision, eye strain, headache, makes difficult visual tasks such as reading, driving (especially at night), focusing on the classroom board and computer screen. This study determined the prevalence, distribution and determinants of astigmatism in Owerri, Imo State, Nigeria in order to establish a baseline data for the state. Materials and Methods: Three thousand, four hundred and fifty - one adults consisting of 2606 persons as test subjects and 845 persons as controls were randomly selected for the study. Structured - questionnaire was administered to the subjects and thereafter, the visual acuity at far and near including tonometry, ophthalmoscopy, perimetry, retinoscopy and subjective refraction were done. Astigmatic correction was prescribed in the minus cylinder format and astigmatism was defined as a cylindrical error less than -0.50 diopter cylinder in any axis. Astigmatism was classified by axis as with-the-rule (WTR), against-the-rule, and oblique astigmatism. Results: A prevalence of 20.9% and 22.5% of astigmatism was found in the study and control groups respectively. From the astigmatics, 59.4% and 61.1% of females in the study and control groups respectively (especially females aged 40-49) were mostly affected. WTR astigmatism of ≤1.00DC (P = 0.000) was statistically significant between study and control groups. A higher prevalence of astigmatism was found in subjects domiciled in the rural areas and caused by factors like environmental influences, poor nutrition and irrational first line drug use of chloroquine. Conclusion: To achieve the targets of vision 2020, we recommend periodic visual examination and health education on diet, drug use and safe environmental practises especially for people living in rural areas in low income economy like ours.

Refractive and Topographic Errors in Topography-guided Ablation Produced by Epithelial Compensation Predicted by 3D Artemis VHF Digital Ultrasound Stromal and Epithelial Thickness Mapping

To describe and quantify the errors inherent to topography-guided ablation of irregular corneas due to natural epithelial thickness compensatory remodeling. Artemis very high-frequency (VHF) digital ultrasound scanning (ArcScan Inc) was performed on a cornea that had undergone radial keratotomy with inferior and superior trapezoidal keratotomies, resulting 27 years later in high irregular astigmatism (+6.50 -8.00 × 101) and severe loss of corrected distance visual acuity (CDVA) to 20/50. The epithelial thickness profile was highly irregular, masking a significant proportion of the true stromal irregularity from front corneal surface topography, which would have resulted in significant inaccuracies had a topography-guided ablation been performed. The stromal ablation pattern of a transepithelial phototherapeutic keratectomy (PTK) ablation was modeled, which appeared logically to reduce the areas of abnormal stromal surface elevation and resembled a hyperopic astigmatic ablation of approximately 3.50 diopters of cylinder. Artemis-assisted transepithelial PTK was performed to target the stromal irregularity masked by epithelium. Artemis-assisted transepithelial PTK induced a refractive change similar to that predicted (+2.24 -3.97 × 120), demonstrating the refractive shift produced by the epithelium. The epithelial thickness profile became relatively regular and CDVA returned to 20/20⁻². Two topography wavefront-guided ablations were performed to correct the remaining topographic irregularity and refractive error, resulting in a near plano refraction, significantly lower higher order aberrations, and CDVA of 20/20⁺². A knowledge of stromal surface shape and power shift produced by epithelial thickness profile alterations after corneal surgery has the potential of improving the efficacy and safety of custom corneal ablation.

Childhood Pterygium: A Descriptive Study of 19 Cases Presented to a Tertiary Eye Care Center

To describe the demographic features, clinical characteristics, and management in cases of childhood pterygium. Observational case series. A retrospective review was done of 19 children (total 26 eyes) under the age of 16 years, consecutively presenting with pterygium and evaluated at a single tertiary care center between January 2000 and August 2011. The main outcome measures were clinical features, associated ocular or systemic diseases, approach towards its management, and histopathology of operated cases. Of the 19 patients, 10 were girls and 9 were boys. The mean age at presentation was 10.63 ± 3.48 years (range 2-15 years). Seven patients (37%) had bilateral involvement. None of the cases had familial history. The median refractive astigmatism was found to be -0.5 diopter cylinder. All the eyes had primary pterygium, except 1, which was recurrent. The majority of the eyes (85%) were managed conservatively. Four eyes (15%) required surgery, where pterygium excision with conjunctival-limbal autograft with fibrin glue application was done. The follow-up of surgical cases ranged from 5 to 38 months (median 6 months). One operated case recurred 1 year after surgery. Development of pterygium is a possibility in younger age groups. No specific predisposing factors, either environmental or familial, were identified as contributing to childhood pterygium. The majority of the cases required conservative management.

Myopia Control with Orthokeratology Contact Lenses in Spain: Refractive and Biometric Changes

To compare axial length growth between white children with myopia wearing orthokeratology contact lenses (OK) and distance single-vision spectacles (SV) over a 2-year period. Subjects 6 to 12 years of age with myopia -0.75 to -4.00 diopters of sphere (DS) and astigmatism ≤1.00 diopters of cylinder (DC) were prospectively allocated OK or SV correction. Measurements of axial length (Zeiss IOLMaster), corneal topography, and cycloplegic refraction were taken at 6-month intervals. Thirty-one children were fitted with OK and 30 with SV. Following 24 months, axial length increased significantly over time for both the OK group (0.47 mm) and SV group (0.69 mm; P < 0.001), with a significant interaction between time and group (P = 0.05) reflecting a greater increase in the SV group. Significant differences in refraction were found over time, between groups and for the interaction between time and group for spherical (all P < 0.001) but not cylindrical components of refraction (all P > 0.05). Significantly greater corneal flattening was evident in the OK group for the flatter and steeper corneal powers and for corneal shape factor (all P ≤ 0.05). Orthokeratology contact lens wear reduces axial elongation in comparison to distance single-vision spectacles in children.

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.

AcrySof toric intraocular lens for post-keratoplasty astigmatism

We report a 63-year-old male who had undergone left eye optical penetrating keratoplasty for central leucomatous corneal opacity 10 years earlier. The eye had clear donor graft with residual astigmatism of –6.50 diopter cylinder (DC) at 30°. The patient underwent clear corneal phacoemulsification with implantation of +6.0 D spherical equivalent AcrySof SN60T9 intraocular lens (IOL). Postoperatively, at 10 months, the patient had distance corrected visual acuity of 20/30 with –2.00 DC at 20°. AcrySof toric IOL offers an effective treatment option for post-keratoplasty high corneal astigmatism in patients with cataract.

Visual Acuity with Astigmatic Blur

To determine how high- and low-contrast visual acuities are affected by blur caused by crossed cylinder lenses. Crossed cylinder lenses of power 0 (no added lens), +0.12 diopter sphere (DS)/-0.25 diopter cylinder (DC), +0.25 DS/-0.50 DC and +0.37/-0.75 DC were placed over the correcting lenses of the right eyes of eight subjects. Negative cylinder axes used were 15 to 180° in 15° step for the two higher crossed cylinders and 30 to 180° in 30° steps for the lowest crossed cylinder. Targets were single lines of letters based on the Bailey-Lovie chart. Successively smaller lines were read until the subject could not read any of the letters correctly. Two contrasts were used: high (100%) and low (10%). The screen luminance of 100 cd/m, in combination with the room lighting, gave pupil sizes of 4.5 to 6 mm. High-contrast visual acuities were better than low-contrast visual acuities by 0.1 to 0.2 log unit (1 to 2 chart lines) for the no added lens condition. Based on comparing the average of visual acuities for the 0.75 D crossed cylinder with the best visual acuity for a given contrast and subject, the rates of change of visual acuity per unit blur strength were similar for high contrast (0.34 ± 0.05 logarithm of the minutes of arc resolution/D) and low contrast (0.37 ± 0.09 logarithm of minutes of arc of resolution/D). There were considerable asymmetry effects, with the average loss in visual acuity across the two contrasts and the 0.50 D/0.75 D crossed cylinders doubling between the 165° and 60° negative cylinder axes. The loss of visual acuity with 0.75 D crossed cylinders was approximately twice times that occurring for defocus of the same blur strength. Small levels of crossed cylinder blur (≤0.75 D) produces losses in visual acuity that are dependent on the cylinder axis. Crossed cylinders of 0.75 D produce losses in visual acuity that are twice those produced by defocus of the same blur strength.

Corneal Changes After Suspending Contact Lens Wear in Early Pellucid Marginal Corneal Degeneration and Moderate Keratoconus

This case study reports on how refraction, visual acuity, and ocular higher-order aberrations changed after rigid gas-permeable (RGP) lens wear was suspended by a patient with early pellucid marginal corneal degeneration (PMD) and by a patient with moderate keratoconus. Alterations in central corneal power and axes, central corneal thickness, and corneal topography were also explored. Ocular aberrations and Scheimpflug photography were measured at 2 visits, 7 days apart, after the patients had removed their contact lenses. Subjective refraction and logarithm of the minimum angle of resolution visual acuities were also recorded at both visits. In contrast to the keratoconic patient, the patient with early PMD showed changes in subjective refraction (approximately -1.75 diopter cylinder of astigmatism), front surface central powers (∼1.3 diopter [D] horizontally and 2 D vertically), and anterior surface topography (∼1.2 D) between visits. Both patients showed an increase in total higher-order root mean square (HORMS) aberrations after suspending lens wear (∼0.40 μm for the moderately keratoconic patient and 0.22 μm for the early PMD patient). Changes in the optical and structural parameters of the cornea after suspending lens wear are likely to be dependent on a multitude of factors, such as the lens fitting and the biomechanical properties of the cornea. The findings of this report may be useful to practitioners when refracting or refitting existing RGP lens wearers with ectasia or to those involved in prescribing aberration-controlling contact lenses for conditions such as keratoconus and PMD.

Effect of uncorrected astigmatism on vision

To examine the effect of uncorrected astigmatism in older adults. University vision clinic. Investigational simulation. Healthy adult presbyopes had astigmatism of 0.00 to -4.00 diopters cylinder (DC) × 90 degrees and -3.00 DC × 90, × 180, and × 45 degrees induced with spectacle lenses, with the mean spherical equivalent compensated to plano, in random order. Visual acuity was assessed binocularly using a computerized test chart at 95%, 50%, and 10% contrast. Near acuity and reading speed were measured using standardized reading texts. Light scatter was quantified with a C-Quant straylight meter and driving reaction times with a computer simulator. Visual clarity of a mobile phone and computer screen was subjectively rated. Distance visual acuity in the 21 volunteers decreased with increasing uncorrected astigmatic power (F = 174.50, P < .001) and at lower contrasts (F = 170.77, P < .001). Near visual acuity and reading speed also decreased with increasing uncorrected astigmatism power (P < .001). Light scatter was not significantly affected by uncorrected astigmatism (P > .05); however, the reliability and variability of measurements decreased with increasing uncorrected astigmatic power (P < .05). Driving simulator performance was unaffected by uncorrected astigmatism (P > .05), although subjective rating of clarity decreased with increasing uncorrected astigmatic power (P < .001). Uncorrected astigmatism at the 45-degree or 180-degree orientation resulted in worse distance and near visual acuity and subjective-rated clarity than at the 90-degree orientation (P < .05). Uncorrected astigmatism, even as low as 1.00 D, caused significantly decreased vision and if left uncorrected could significantly affect patients' independence, quality of life, and well-being.

Astigmatism correction in cataract surgery with Rayner toric intraocular lenses

Correspondence: sally L Painter Oxford eye hospital, John radcliffe hospital, headley Way, headington, Oxford, OX3 9DU, United Kingdom Tel +44-1865-234800 Fax +44-1865-234800 email sallylpainter@gmail.com Background: Cataract surgery is increasingly regarded as a refractive procedure. Corneal astigmatism can be reduced by the insertion of a toric intraocular lens (T-IOL). Rayner T-flex T-IOLs are licensed for the correction of astigmatism. Methods: In this retrospective study, 46 eyes from 34 patients, in whom T-IOLs were inserted, have been examined. Astigmatism was analyzed using power vectors. Results: Postoperatively, 72% had unaided vision of 6/9 or better, with 42% having ,0.25 diopters (D) of residual cylinder and 78% having ,1.5 D of residual cylinder, compared with 6.9% preoperatively. Once astigmatism had been converted to power vectors, J 0 (measure of astigmatism with an axis of 0°) reduced in magnitude from −0.81 D ± 0.85 to 0.09 D ± 0.42 (P , 0.001). Conclusion: Rayner T-flex lenses can be reliably used to correct corneal astigmatism.

Clinical Review of Periorbital Capillary Hemangioma of Infancy

To explore the role of intralesional steroid injections (ILSI) and oral steroids in the management of periocular hemangioma of infancy (HOI). In this retrospective study, treatment options studied were observation, ILSI, and oral steroids. All children received adjunctive amblyopia treatment if required. The main indications for treatment were cosmetic, worsening astigmatism, and visual axis obscuration. Success was defined as complete HOI regression before the age of 5 years (cosmetic group), reduction of astigmatism of at least 1 diopter cylinder (DC) (astigmatism group), or no evidence of amblyopia at the last follow-up (visual axis obscuration group). Twenty-four of 41 children (58.5%) had amblyopia at presentation. Eighteen children formed the observation group, 17 children received ILSI, and 6 children received oral steroids. Successful outcome was achieved in all except 2 patients in the cosmetic group and 6 of 7 in the visual axis obscuration group. Mean astigmatic correction of all cases was 1.65 ± 1.34 DC before treatment and 0.91 ± 1.17 DC after treatment, the change being statistically significant (P < .001). Observation appears to be a highly effective strategy if coupled with amblyopia therapy, especially for mild cases. Intralesional and oral steroids appear to be equally effective for lesions requiring treatment, but their exact role cannot be clearly determined in the presence of a spontaneously resolving lesion.

The Preoperative Prognostic Factors for Outcome After LASEK Using the MEL60

Purpose: To investigate the preoperative clinical factors affecting the refractive outcome after laser-assisted subepithelial keratomileusis (LASEK). Methods: This retrospective study was conducted on 58 patients (116 eyes) who underwent bilateral LASEK using the MEL60. The outcome efficacy and predictability of LASEK was examined by analyzing data including age, gender, preoperative uncorrected visual acuity, preoperative refraction (spherical equivalent and cylindrical diopter), central corneal thickness, tear breakup time, and Schirmer test through multiple logistic regression analysis. Results: The preoperative factor associated with postoperative uncorrected visual acuity was the amount of preoperative spherical equivalent. Greater preoperative spherical equivalent was associated with decreased efficacy. Predictability was also associated with the amount of preoperative spherical equivalent. Greater preoperative spherical equivalent was associated with decreased predictability. The other preoperative factors including sex, age, preoperative uncorrected visual acuity, amount of preoperative cylinder diopter, intraocular pressure, tear breakup time, Schirmer test and central corneal thickness did not show any association with efficacy or predictability. Conclusions: The preoperative spherical equivalent was determined as the most important prognosis factor in LASEK, as it is in PRK or LASIK.

Astigmatic Changes in Orthokeratology

To investigate and compare changes in refractive astigmatism and corneal toricity in orthokeratology (ortho-k) using the Thibos vector analysis. Consecutive records of 74 patients (aged 7 to 16 years) who were fitted with spherical ortho-k lenses at the Optometry Clinic of The Hong Kong Polytechnic University between April 2000 and November 2003 and who had been on the treatment for at least 6 months were reviewed. Manifest refractive error and topographic data were retrieved from the right eye for data analysis. Changes in refractive astigmatism and corneal toricity were evaluated using the Thibos vectors (refractive vectors, RJ 0 and RJ 45; corneal vectors, CJ 0 and CJ 45) among the astigmats (refractive astigmatism 0.75 diopters cylinder (DC) or above) and the non-astigmats (refractive astigmatism 0.50 DC or less). The mean changes in refractive astigmatism, RJ 0 and RJ 45 were 0.51 +/- 0.51 diopter (D), -0.31 +/- 0.35 D, and 0.09 +/- 0.16 D, respectively, among the astigmats; and 0.01 +/- 0.36 D, 0.00 +/- 0.17 D, and 0.03 +/- 0.13 D, respectively, among the non-astigmats. RJ 0 was significantly reduced, and RJ 45 was significantly increased only in the astigmats (one sample t tests, astigmats: p < 0.01; non-astigmats: p > 0.10). Although there were significant correlations between the initial RJ 0 and RJ 45 with their changes in all subjects and in the astigmats, only 21 to 55% of the variability could be explained by the regression equations (Pearson r: all subjects -0.63 < r < -0.62; astigmats -0.74 < r < -0.46, p < 0.001). No significant changes in corneal toricity and no correlations between the changes in refractive astigmatism and changes in corneal toricity were found (p > 0.13). Spherical ortho-k leads to significant changes in RJ0 and RJ45, but only 38% of the variance of the changes in all subjects could be explained by relationship between changes and the initial RJ0 or RJ45. No correlation between changes in refractive astigmatism and changes in corneal toricity was found, and ortho-k treatment did not induce astigmatism in our non-astigmatic subjects.