Effect of pterygium excision on pterygium induced astigmatism.
(49/358)
Pterygium is known to affect refractive astigmatism, which can have a significant impact on vision. This study was undertaken to evaluate the effect of pterygium excision on refractive astigmatism. Thirty-six eyes with primary pterygium with astigmatism of 2D or more were analysed before and after pterygium excision. Astigmatism increased with the increase in the grade of pterygium (P = 0.000001). The preoperative refractive cylinder decreased from 4.60 +/- 2D to 2.20 +/- 2.04D (P = 0.00001) after pterygium excision. (+info)
Refractive error changes in cortical, nuclear, and posterior subcapsular cataracts.
(50/358)
AIMS: To determine the effect of the three main morphological types of cataract on refractive error. METHODS: Data were prospectively collected from 77 subjects (age 67 (SD 8) years) with one morphological type of cataract. 34 had cortical, 21 had nuclear, and 21 had posterior subcapsular cataract. 22 subjects with clear lenses (60 (7) years) were recruited as controls. The spherical equivalent and astigmatic vector change between spectacle correction and optimal refraction were calculated. RESULTS: The cortical cataract group showed a significant astigmatic change of 0.71 (0.67) D (mean (1 SD)) compared to the control group (0.24 (0.20) D), with 24% outside the 95% confidence limit (0.63 D). The nuclear cataract group showed a significant myopic shift of -0.38 (0.60) D compared to the control group (+0.02 (0.21) D), with 52% beyond the minus 95% confidence limit (-0.39 D). CONCLUSION: A quarter of subjects with cortical cataract showed larger changes in astigmatism than subjects with clear lenses. This is probably because of the localised refractive index changes along cortical spoke opacities within the pupillary area. The well known myopic shift of nuclear cataract was also demonstrated. (+info)
Visual outcomes and amblyogenic risk factors in craniosynostotic syndromes: a review of 141 cases.
(51/358)
AIMS: To determine the visual outcome and prevalence of amblyogenic risk factors in children with craniosynostotic syndromes. METHODS: The case notes of 141 children seen within the craniofacial unit were reviewed and information retrieved on date of birth, age at first and last examination, cycloplegic refraction at last visit, best corrected visual acuity at last visit, horizontal ocular deviation in primary position at first visit, and alphabet pattern if any. The presence of astigmatism, its magnitude, and orientation of axis were determined. RESULTS: 40.3% of patients had 1 dioptre (D) of astigmatism or greater and, of these, 64% had oblique astigmatism in at least one eye. Anisometropia of 1D or more was found in 18% of patients (age matched normals 3.5%). Horizontal strabismus was found in 70% (38% exotropia, 32% esotropia). Visual outcome results showed 39.8% of patients (45 of 113) had visual acuity of 6/12 or worse in their better eye. CONCLUSION: In the largest study to date a poor visual outcome was shown in children with Crouzon's, Pfeiffer's, Apert's, and Saethre-Chotzen syndromes (39.8% with 6/12 or worse in the better eye) together with significant prevalence of amblyogenic risk factors. (+info)
The effect of anisometropia on binocular visual function.
(52/358)
PURPOSE: To investigate the effects of anisometropia on binocular vision. METHODS: One to three dioptres of unilateral hyperopia, myopia or astigmatism was induced in 30 normal adults. The effect on binocularity was assessed with the Worth-four dot test, Titmus stereo test and Bagolini's lenses. RESULTS: Binocular vision deteriorated with increasing anisometropia. Spherical anisometropia was more deleterious than astigmatic anisometropia. CONCLUSION: In addition to amblyopia, the potential effect of anisometropia on binocular vision should be considered while prescribing spectacles in young children during the sensitive period. (+info)
Cost-efficient vision screening for astigmatism in native american preschool children.
(53/358)
PURPOSE: To design and test a cost-efficient, community-based vision screening program for a population of Native American preschool children in which there is a high prevalence of astigmatism. METHODS: Based on analysis of vision screening and eye examination data from a preschool population with a 33% prevalence of astigmatism, comparative costs to conduct a 1000-child screening program with a target sensitivity of 90% were estimated for photoscreening, noncycloplegic autorefraction, autokeratometry, and Lea symbols distance visual acuity testing. Results of the cost analysis and examination of sensitivity and specificity data from the preschool population led to development of a hybrid screening program of autokeratometry and visual acuity screening with referral thresholds of 2.25 D of corneal astigmatism or inability to read a 20/63 Lea symbols line on two separate attempts. The screening program was prospectively implemented in a community-based screening of a similar cohort of 167 children, and its efficiency was evaluated by comparison to results of cycloplegic refraction. RESULTS: The community-based screening showed 96.8% sensitivity and 79.2% specificity for detecting the presence of refractive astigmatism of 1.50 D or more. CONCLUSIONS: Referring children who have at least 2.25 D of corneal astigmatism or acuity worse than 20/63 on two attempts, provides the high sensitivity and specificity associated with automated keratometry while maintaining an acuity component that can detect other causes of reduced acuity in the absence of astigmatism. (+info)
Radial keratotomy for the purpose of reducing glasses power in high myopia.
(54/358)
Anterior radial keratotomy for high myopia (over-6.25 diopter) to reduce refractive error was not able to dispense with glasses or contact lenses due to the high myopia itself. However patients could see objects well and were free of dizziness while wearing glasses of relatively reduced power. We performed anterior radial keratotomies on 83 high myopic and/or astigmatic eyes of 47 patients at Kangnam St. Mary's Hospital between May 1990 and Mar. 1991. Eight radial incisions with a diamond blade were performed and the Ruiz technique was added for astigmatism of over 2.0 diopters. The depth of incision was 90 to 95% of corneal thickness and the optical zone was 3mm in diameter. Patients were followed up on postoperative 7 days. 1 month, 3 months, 6 months, 1 year and thereafter. Uncorrected visual acuity of 20/40 or better after radial keratotomy could be obtained in 19.6% of high myopic eyes. A mean reduction of the spherical equivalent cycloplegic refraction of 5.13 diopters and a keratometric reading of 3.89 diopters after radial keratotomy were observed. About 90% of patients were satisfied with their visual outcome with reduced refractive power glasses. We recommend radial keratotomy for high myopic patients to reduce the refractive power and to help them enjoy a more comfortable life. (+info)
Selective suture cutting for control of astigmatism following cataract surgery.
(55/358)
Use of 10-0 monofilament nylon in ECCE cataract surgery leads to high with the rule astigmatism. Many intraoperative and post operative methods have been used to minimise post operative astigmatism. We did selective suture cutting in 38 consecutive patients. Mean keratometric astigmatism at three and six weeks post operative was 5.76 and 5.42 dioptres (D) respectively. 77.5% of eyes had astigmatism above 2 D. Selective suture cutting along the axis of the plus high cylinder was done after six weeks of surgery. Mean post suture cutting keratometric astigmatism was 3.3 D and 70% of the eyes had astigmatism below 2 D. After 3 months of surgery mean keratometric astigmatism was reduced to 1.84 D. Axis of the astigmatism also changed following suture cutting. 40% of the eyes showed improvement in their Snellen acuity following reduction in the cylindrical power. (+info)
Optimal postoperative refraction for good unaided near and distance vision with monofocal intraocular lenses.
(56/358)
Forty five eyes with up to 2 dioptres of myopic astigmatism and up to 1 dioptre sphere either plus or minus following cataract extraction and implantation of a monofocal intraocular lens were examined to assess their unaided visual acuities. Forty three percent were able to see 6/12 and N8, and 60% were able to see 6/12 and N10. Subjects with between 1 and 2 dioptres of myopic astigmatism and virtually no sphere were able to see 6/12 and N10 in 82% of cases. This study confirms the benefits to both distance and near vision of myopic astigmatism as an alternative to multifocal intraocular lenses. (+info)