Refractive Error May Influence Mesopic Pupil Size

The Fortune Optical (Tomey ViVA) VRB-100 video refractor was tested to determine its accuracy and precision in measuring manifest refractions of human eyes with and without cycloplegia. The specific issues addressed included its accuracy in measuring spherical and cylindrical refractive errors and its precision in refracting near emmetropia. To determine its ability to measure moderate to high (> 4.00 D) myopia, we compared the VIVA's refractions to those taken by a Canon Autorefractor R1 and a retinoscopist. A spherical lens series from -7.00 to + 7.00 D at 1.00 D intervals, or -5.00 to + 5.00 at 0.50 D intervals, was placed over a subject's eye, which was then covered by an infrared (IR) filter, refracted, and analyzed to determine the VIVA's ability to measure spheres. Subjects with refractive errors of -2.00 to + 2.00 DS (diopters sphere) and 0 to 1.00 DC (diopters cylinder) were refracted 7 to 15 times during 1 sitting to determine the VIVA's precision. The instrument's accuracy in measuring cylinders was tested by placing + 3.00 to -3.00 D cylinders (at 0.50 D intervals) over the eyes of subjects at 0 degree, 45 degrees, 60 degrees, 75 degrees, 90 degrees, 105 degrees, 120 degrees, and 135 degrees. The VIVA measured spheres of +/- 3.00 D with a root mean squared (rms) error of 0.5 +/- 0.1 D. Beyond this power, its accuracy progressively worsened. In some subjects, irregular intensity profiles compromised the VIVA's accuracy even with low spherical refractive errors. The VIVA was very precise in measuring spheres from + 2.00 to -2.00 D and cylinders from 0 to 1.00 D. Although the ViVA adequately measured all cylinder powers at 0 degree and 90 degrees, the accuracy of cylindrical power measurement decreased with obliquity; only cylinders < or = 1.00 D magnitude were accurately measured at 45 degrees and 135 degrees. We conclude that, although the ViVA offers many attractive features for vision screening, it is seriously limited by its inability to property detect and measure oblique astigmatic errors.

The Child Self-Refraction Study: Results from Urban Chinese Children in Guangzhou

Purpose: To evaluate changes in visual acuity, refraction, and keratometric (K) readings after implantation of five millimeters versus six millimeters optical diameter of intracorneal ring segments (ICR) for treatment of keratoconus grade (2-4). Patients and methods:A prospective nonrandomized clinical comparative study.Thirty four eyes were included in this study.They were classified into two groups: Group I: Seventeen eyes of patients with Keratoconus grades (2-4) were subjected to 5 mm optical diameter intracorneal ring implantation.Group II: Seventeen eyes of patient with keratoconus grade (2-4)were subjected to 6 mm optical diameter intracorneal ring implantation.Results: Thirty four eyes of 22 patients (9 males and 13 females) with keratoconus grade (2-4) were enrolled in this study.The mean age + SD of the patients in group I was 26.36 ± 7.06 years and in group II was 23.09 ± 6.92 years.The mean keratometric (K) reading decreased from 50.05 ± 3.64D.to 46.96 ± 4.42D in group I and from50.48± 5.18D to 46.91 ± 5.44D in group II.There was a statistically significant improvement in the postoperative uncorrected distance visual acuity, corrected distance visual acuity, K readings, manifest spherical and cylindrical refractive errors, and spherical equivalent in both groups.No serious intraoperative complications were reported.Conclusion: Both 5mm and 6mm ICR improve significantly UCVA, BCVA, decreased the corneal power and corneal astigmatism but 6 mm showed significant improvement in cylindrical errors and BCVA compared to 5 mm ICR.

PurposeTo evaluate the pupillary dynamics in patients with serum vitamin D (25(OH)-D) levels below normal and compared with healthy controls.MethodsThis study included 132 patients and 76 healthy controls. Serum 25(OH)-D concentrations within the range of 10 to 30 ng/mL were classified as vitamin D insufficiency (VDI, Group 1), while those at or below 10 ng/mL were categorized as vitamin D deficiency (VDD, Group 2). The static phase of pupillometry, including scotopic, mesopic, and photopic pupil diameters, was evaluated. Additionally, in the dynamic phase of pupillometric evaluation, pupil dilation velocity (mm/sec) was calculated. These values were compared between patient and control groups.ResultsIn static pupil diameters, only photopic pupil diameters were significantly different between Groups 1 and 2 compared to the control group (p = 0.012 and p = 0.008, respectively). In dynamic measurements, the pupil diameter values showed a statistically significant difference between the patient and control groups (p = 0.003). In intragroup comparison, the mean pupil diameter was 3.42 ± 0.81 mm in group 1 and 3.94 ± 0.96 mm in group 2 (p = 0.029). Mean pupil dilation velocity was significantly slower in the patient group (p < 0.001). In intragroup comparison, the mean pupil dilation velocity was 0.162 ± 0.049 mm/sec in group 1 and 0.088 ± 0.032 mm/sec in group 2 (p < 0.001).ConclusionWe demonstrated that VDD alters pupillary functions with objective measurements. Our study may shed light on the role of vitamin D in multisystemic diseases since it is expressed in many tissues and has multiple functions. Multicenter studies with a large number of participants are needed in the future.

Objective: To investigate the refractive status and frequency of amblyopia risk factors in children who underwent probing for unilateral nasolacrimal duct obstruction (NLDO). Material and Methods: This descriptive cross-sectional study included 65 consecutive children with unilateral congenital NLDO who were still symptomatic at one year examination and necessiated nasolacrimal duct probing. A complete ophthalmic evaluation including cycloplegic refraction was performed. The spherical, cylindrical and spherical equivalent retinoscopy measurements of both eyes were noted. The risk factors for amblyopia and differences between refractive values of both eyes were evaluated. Results: The mean age at presentation was 20.4±9.2 months (range, 12 to 48 months). The left eye was involved in 30 (46.2 %) patients. Thirty-five subjects (54 %) were female. Nine children had amblyopia risk factors (13.8%). There was no statistically significant difference regarding cylindrical refractive error, spherical refractive error and spherical equivalent (p=0.9, p=0.9 and p=0.5 respectively) between two eyes. Conclusion: In the current study, no statistically significant difference was found between refractive values of both eyes. One tenth of children in our study group were found to be under risk of amblyopia mostly due to high astigmatism. Further studies about the effect of blurred vision on visual development of both eyes and binocular vision may provide more information about the refractive status in this group of patients.

Objective To investigate the changes in ocular astigmatism which were induced by the accommodation stimulus range of 1-5D. Methods This was a prospective case-control study.Forty-nine eyes of 49 normal subjects aged 23-36 years,with the best spectacle corrected visual acuity (better than 1.0).The changes of spherical and cylindrical refractive errors were measured by an open-field infrared autorefractor. Results It was found that,for most subjects in the group,the mean sphere change being (-0.932±0.165)D (F=-41.98,P =0.000),astigmatism changed in the with-the-rule direction,the mean J0 change being (0.047±0.092)D,the mean J45 change being (-0.011±0.067)D,for each diopter of accommodation response.The change of J0 was larger than the change of J45 (F =3.865,P =0.000),when effective accommodation stimulus were provided range of 1-5D. Conclusions The changes of astigmatism might reflect increases in lens tilt about a horizontal axis,caused by the combined effects of a slacker zonule and gravity.The changes in lens tilt will be expected to produce changes in with-the-rule astigmatism. Key words: Astigmatism; Accommodation; Eye

Association of refractive error with vision-related quality of life in junior high school students

Objective To observe the orientation of dynamically stabilized toric soft contact lenses (TCL) in Chinese subjects and discuss the effect of myopic refractive error,the amount of astigmatism and its axis.Methods This was a prospective clinical study.One hundred and ninety one subjects were fitted with dynamically stabilized TCLs.Subjects were classified into different groups based on the amount of sphere,cylinder and cylinder axis.The amount of rotation and stability of the lenses in the right eye was recorded and their relationship with myopic refractive error,astigmatic amount and axis were analyzed.Data were analyzed with ANOVA,Fisher's exact test and Wilcoxon signed-rank test.Results There was no difference between corrected visual acuity of the dynamically stabilized TCLs and that of spectacles (Z=-1.061,P＞0.05).The lenses had good centralized positioning and mobility.Lenses on eyes with non-oblique and greater amounts of astigmatism became relatively stable within a shorter time.Lenses in the high myopia group had better stability compared with the moderate myopia group (x2=5.371,P＜0.05).The amount of rotation was higher in the oblique astigmatism group than in with-the-rule and against-the-rule astigmatism groups (x2=7.046,P＜0.05; x2=6.462,P＜0.05).The higher the astigmatism,the better the stability and the less amount of lens rotation.Conclusion Spherical refractive error,amount of astigmatism and axis affect the orientation of dynamically stabilized TCLs to some extent.People with high myopia and against-the-rule astigmatism were the ideal subjects for fitting dynamically stabilized TCLs. Key words: Myopia ; Astigmatism ; Contact lenses,hydrophilic ; Toric

Objective To investigate changes in refractive trends error of children with mixed astigmatism.Method Sixty three patients (113 eyes) with mixed astigmatism between 3 and 16 years of age were confirmed as mixed astigmatism with cycloplegic retinoscopy.Participates were performed optometric examination annually over a 3 year period.Refractive status data were collected and trends of in refractive error changes were analyzed.Result The astigmatic values remained stable over three year period (F =0.175,P =0.840),which indicated the maximum and minimum refractive trends errors could help the evolvement.There was a statistically highly significant difference in degrees of spherical lens that appeared to gradually decreased (F =14.151,P =0.000).Conclusions Refractive status can evolve into myopia as growth and development of ocular optical components in children with mixed astigmatism.Early screening and cum correction is advantageous to the children with mixed astigmatism.It is also highly recommend that cycloplegic retinoscopy is a very important and necessary method for diagnosis and therapy of children with mixed astigmatism. Key words: Children; Mixed astigmatism; Refraction

To determine if videokeratography-based pupil measurements are an accurate method of estimating pupil size under mesopic conditions. Sixty patients who had a preoperative work-up for refractive surgery participated in the study. A single observer obtained detailed pupil measurements with the Colvard pupillometer under standardized lighting conditions. The same observer recorded pupil size measurements obtained automatically when corneal topographic analysis was performed with Humphrey videokeratography. The Colvard pupillometry low light group was statistically different (P < .0001) from the Humphrey videokeratography automatic pupil measurement group. We calculated the value at which the Humphrey pupil measurements can accurately predict which patients would have pupil diameters > or = 6.5 mm under low mesopic conditions. By adding a constant of 2.6 mm to the Humphrey videokeratography pupil measurement, 100% of patients with a pupil diameter > or = 6.5 mm under low mesopic conditions were detected (sensitivity 100%). However, the ability to correctly reject those patients who do not have pupil diameters > 6.5 mm under low mesopic conditions was lower at 55% (specificity). Videokeratography units can be used as a rapid, simple, and accurate method of predicting pupil size under mesopic conditions for potential refractive surgery patients and can provide a permanent record of pupil size. Care should be taken when relying on topography pupil sizes and more accurate measurements of mesopic and scotopic pupil sizes should be obtained.

To compare densitometric outcome of two techniques of deep lamellar keratoplasty using Pentacam HR corneal densitometry software. Postoperative outcomes of 31 patients with big bubble (BB) and 28 patients with Melles (M) surgery for the treatment of keratoconus were evaluated. Data were gathered at least 3months after the removal of all sutures including demographic data, uncorrected distance visual acuity (UCDVA), best spectacle-corrected visual acuity (BSCVA), refraction and endothelial cell count. Moreover, the Scheimpflug images were taken by Pentacam® HR to assess keratometric profile, densitometric outcomes in different depths and zones of the cornea and central corneal thickness. Anterior segment OCT was performed in ten cases of M group. Thirty-one eyes with BB and 27 eyes M surgery were enrolled. Comparison of densitometric profile between groups revealed no statistical significance in zone 0-2mm, zone 2-6mm and zone 10-12mm in all depths (all P values > 0.05). Zone 6-10mm of M group had lower densitometric readings (more transparent) in anterior, central and posterior layers of the cornea in comparison with BB group (all P < 0.05). Also no statistical difference was found in UCDVA, BSCVA, spherical or cylindrical refractive error, and spherical equivalent, keratometric readings, endothelial cell count and central corneal thickness in two groups (all P values > 0.05). Densitometric profiles were identical in both methods in visually important zones so as visual and refractive outcomes.

To compare visual and refractive results, contrast sensitivity, and tear stability after laser in situ keratomileusis (LASIK) in one eye and laser epithelial keratomileusis (LASEK) in the fellow eye for low myopia. Patients diagnosed with low myopia, with a maximum difference of 1 D between their two eyes, were randomly assigned to receive LASEK on one eye and LASIK on the other eye. A total of 64 eyes of 32 patients with a mean age of 26.83 +/- 5.33 years were included in the study. Preoperative myopia ranged from -1.00 to -6.00 D. Follow-up was 6 to 12 months. Uncorrected (UCVA) and best spectacle-corrected visual acuity (BSCVA), Schirmer test results, tear break-up time, corneal asphericity, corneal uniformity index, predicted corneal acuity, and contrast sensitivity values were compared with preoperative values. A Wilcoxon test was used for statistical comparisons and a P-value less than .05 was considered significant. At 6 months after surgery, there was no statistically significant difference in UCVA, BSCVA, spherical and cylindrical refractive error, Schirmer test, or tear break-up time between groups. Contrast sensitivity values in the LASIK eyes were lower in comparison to preoperative values, but there was no change in the LASEK group. Based on 6-month results, LASEK for low myopia was safe and effective with predictable results, offered early refractive stability, and may be considered an alternative for LASIK.

Purpose To compare visual acuity, refraction, and topographic corneal changes after implantation of a MyoRing versus Ferrara ring segment for management of keratoconus. Patients and methods This is a prospective nonrandomized clinical comparative study. Forty eyes of 25 patients with keratoconus grades 2–4 were included in the study and were divided into two groups: group A (MyoRing group) included 20 eyes of patients with keratoconus subjected to femtosecond laser-assisted MyoRing implantation and group B included 20 eyes of patients with keratoconus subjected to femtosecond laser-assisted Ferrara ring segment implantation. Results Forty eyes of 25 patients (12 males and 13 females) with keratoconus grades 2–4 were enrolled in this study. The mean age of the patients in group A was 26.62±6.18 years and in group B was 24.72±5.06 years. The mean central corneal thickness improved from 440.25 to 476.57 µm in group A and from 441.35 to 470.63 μm in group B. The mean keratometric (K) reading decreased from 49.97±14.26 to 44.55±2.16 D in group A and from 48.69+4.26 to 44.85±1.92 D in group B. There was a statistically significant improvement in the postoperative uncorrected distance visual acuity, corrected distance visual acuity, K readings, manifest spherical and cylindrical refractive errors, and spherical equivalent in both groups. No serious intraoperative complications were reported. Conclusion Both MyoRing and Ferrara ring segments are effective modalities for treatment of grades 2–4 keratoconus, but MyoRing had a superior capability in improving the keratoconus parameters as well as in halting the progression of the disease.

The aim of this study was to assess the predictability, efficacy, safety, and stability in patients who received a toric implantable collamer lens (TICL) after collagen crosslinking in early-stage keratoconus. This prospective interventional case series study was conducted at the Alexandria Main University hospitals, University of Alexandria, Egypt. Sixteen eyes underwent implantation of a TICL (STAAR Surgical Inc) after crosslinking. The mean spherical refraction was -5.98 ± 4.39 diopters (D) (range, -0.50 to -14.50 D), and the mean cylinder was -4.91 ± 1.51 D (range, -2.50 to -7.75 D). Uncorrected distance visual acuity (UDVA), manifest and cycloplegic refraction, corrected distance visual acuity (CDVA), vault, intraocular pressure, and endothelial cell count (using specular microscopy) were evaluated during a 3-year follow-up. The mean Snellen decimal CDVA improved from 0.56 ± 0.13 (range, 0.40-0.80) preoperatively to 0.89 ± 0.17 (range, 0.60-1.20) at 3 years of the follow-up (P < 0.0001). The mean UDVA also improved significantly from 0.63 ± 0.14 before ICL implantation to 0.88 ± 0.18 after 3 years of the follow-up (P < 0.001). At 3 years, the mean spherical and cylindrical manifest refractions were 0.00 ± 0.18 D and -0.05 ± 0.14 D, respectively. At the end of the follow-up, the vault was 509.75 ± 141.47 μm (range, 320-900) and the intraocular pressure was 11.94 ± 1.12 mm Hg. No complications occurred during the surgical procedures. No eye needed explantation or repositioning of the TICL. The endothelial cell count loss after 3 years was -8.98%. Correction of spherical and cylindrical refractive errors in keratoconic eyes by TICL implantation 12 months after crosslinking gave significantly promising outcomes, particularly in the astigmatic component of refraction.

Background: Dry eye disease (DED) is the most common multifactorial annoying ocular surface disorder, of various ocular symptoms, ranging from eye discomfort, dryness, itching, irritation, and foreign body sensation up to noticeable visual disturbance. Eventually ends with reducing quality of life. Optical refractive quality might deteriorate in these DED individuals, especially in hot-dry-windy climates like in Sudan. Aim: This study aims to determine the influence of spherical refractive errors (REs) on the tear volume and DED. Materials and Methods: In a comparative cross-sectional hospital-based study 90 (n = 90) participants were included; all were free from any ocular or systemic diseases and not using contact lenses. They were of equal numbers of hypermetropes and myopes of mixed gender; males and females, with their ages range between (18-28) years. The mean ages in both groups of RE states were 21.97 ± 2.35 and 22.55 ± 3.29 hypermetropes and myopes, respectively. The study was performed at Makkah Eye complex (MEC), Khartoum, Sudan, from May to July 2015; where the participants were recruited from the general refraction clinics at MEC. All individuals were subjected to the full eye examination. The Schirmer's test was used for all the participants. SPSS statistical analysis program was used to analyze the data. Results: Dry eye was found in 26.6% on hypermetropic patients and 1.1% myopic patients. In this study, the spherical REs showed a significant difference between males (16.6%) and females (12%) P = 0.001. Conclusion: REs may be considered to be one of the risk factors to cause dry eye condition. Correcting RE may reduce the risk factor of dry eye, and that may reduce its prevalence.