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Results for “refractive error”

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At least 1,621 records · Page 90Linked to original sources
PubMed1998

Radial and staggered treatment patterns to correct hyperopia using noncontact holmium:YAG laser thermal keratoplasty.

PURPOSE: To compare the effects of two treatment patterns in the correction of hyperopia by noncontact holmium:YAG laser thermal keratoplasty (LTK). SETTING: Divisione Oculistica, Ospedale S. Gerardo, Monza, Italy. METHODS: Using two treatment patterns, we performed noncontact LTK in one session in 16 eyes of 8 patients with isometropic hyperopic refractive errors; mean preoperative subjective cycloplegic refraction was +4.90 diopters (D) +/- 1.17 (SD). The treatment consisted of 24 spots in three concentric rings of eight spots each; ring diameters were 6.0, 7.0, and 8.0 mm, respectively. Each spot received seven pulses of laser energy at 30 mJ/pulse. We treated one eye of each patient with a radial pattern (the spots of the three rings aligned on the eight semimeridians) and the fellow eye with a staggered pattern (the spots of the contiguous rings at 22.5 degrees from each other). Follow-up at 1, 15, 30, 90, 180, and 360 days included subjective cycloplegic refraction, uncorrected (UCVA) and spectacle-corrected visual acuity (SCVA), computerized videokeratography (CVK), and Scheimpflug camera examination. RESULTS: One year postoperatively, the mean subjective cycloplegic refraction was +2.75 +/- 1.6 D in the eyes treated with the radial pattern and +3.40 +/- 1.6 D in those treated with the staggered pattern; the mean change in subjective cycloplegic refraction was 2.15 and 1.50 D, respectively. Mean UCVA improved by five lines in the radial group and by four lines in the staggered group. Mean SCVA returned to preoperative levels by day 15 in the radial group and at 1 year in the staggered group; at 1 year, SCVA improved by one line in the radial group and remained unchanged in the staggered group. No eye lost one or more lines of SCVA. Refractive astigmatism was essentially unchanged in both groups. Scheimpflug photography and CVK indicated larger and more uniform corrected zones in the radial group. CONCLUSIONS: Radial and staggered patterns effectively corrected low hyperopia, although both were subject to a certain amount of regression. The radial pattern produced faster postoperative recovery of SCVA and demonstrated greater refractive stability.

Adult↗
PubMed2006

Efficacy of nonsimultaneous bilateral LASIK after nonsimultaneous bilateral penetrating keratoplasty.

PURPOSE: To show if nonsimultaneous bilateral laser in situ keratomileusis (LASIK) is a safe and effective procedure for patients with bilateral penetrating keratoplasty (PKP). METHODS: Five patients (10 eyes), with keratoconus, underwent PKP separately in each eye. After an average PKP follow-up of 45.8 months per eye, (range, 19-92 months), each eye underwent 1-stage LASIK using the Visx Star S3 laser to correct its residual refractive error. We used the cycloplegic refraction as the target for the LASIK surgery. Each patient had his or her eyes done separately 3 weeks apart. RESULTS: Pre-LASIK myopia averaged -3.93 +/- 2.9 D, ranging from -10.00 to +0.75 D. Pre-LASIK astigmatism averaged -3.25 +/- 0.80 D, ranging from -1.75 to -4.50 D. Mean pre-LASIK keratometry was 45.4 +/- 2.6, ranging from 42.2 to 50.5. Uncorrected visual acuity pre-LASIK averaged 20/220, ranging from 20/60 to 20/400. Best-corrected spectacle visual acuity (BCSVA) pre-LASIK averaged 20/22, ranging from 20/20 to 20/30. Nine eyes had no complications. One eye had a flap buttonhole during LASIK, and surgery was aborted. No vision was lost in this eye. Mean follow-up after LASIK in the 9 eyes was 17 +/- 15.2 months, (range, 4-56 months). Mean post-LASIK ametropia in these 9 eyes was +0.25 +/- 0.45 D, ranging from -0.50 to +0.75 D. Average post-LASIK astigmatism was -0.33 +/- 0.38 D, ranging from 0 to -0.75 D. In the 9 treated eyes, uncorrected vision post-LASIK averaged 20/25, ranging from 20/20 to 20/30. BCSVA post-LASIK averaged 20/21, ranging from 20/20 to 20/25. No lines of visual acuity were lost in any of the eyes. CONCLUSION: Young patients who have had bilateral PKP, with good postoperative vision and low levels of myopia, astigmatism, and minimal wound override, are good candidates for bilateral nonsimultaneous LASIK. Further studies can now be done on the performance of bilateral simultaneous LASIK in patients who have had corneal transplant surgery in both of their eyes.

Adult↗
PubMed1992

Myopia among medical students in Norway.

In this study the prevalence of myopia and age at onset among medical students were determined. Of the 140 senior medical students at The Faculty of Medicine, University of Trondheim, Norway, 133 (75 females, 58 males) were examined. Visual acuity was tested and the refractive error was measured using automated refraction and clinical refractive technique. The prevalence of myopia was found to be 50.3% in the right eye (n = 67) without significant difference between female and male students. The refractive state was unrelated to body height. Among the myopic students, the mean equivalent sphere was -2.34 +/- 2.01 D in the right eye (range -9.25 D to -0.25 D). A clear relationship was detected between the current amount of myopia and the age at which corrective lenses were first prescribed. However, as much as 43.3% of the myopic students wearing corrective lenses first received these at the age of about 20 years, indicating a relatively high prevalence rate of adult-onset myopia.

Adult↗
PubMed2006

Long term results of primary posterior chamber intraocular lens implantation for congenital cataract in the first year of life.

AIM: To document the long term outcome of congenital cataract surgery with primary posterior chamber (PC) lens implantation in the first year of life. METHOD: A retrospective review of congenital cataract surgery in the first year of life with PC lens implantation in 18 infants, eight with unilateral and 10 with bilateral cataract. The average age at surgery was 15 weeks (range 3-44 weeks). The mean follow up was 95 months (range 60-139 months). RESULTS: The best outcomes were in the bilateral group where 50% of eyes achieved 6/18 or better, with a best acuity of 6/9. Acuities were poor in the unilateral group where only 38% achieved 6/60 or better, with a best acuity of 6/24. There was a mean refractive shift between first refraction after surgery and refraction at 36 months after surgery of -3.44 dioptres with a very wide range (+2.00 to -15.50). There was a significantly greater myopic shift in the unilateral cases. Many eyes in both groups continued to show an increasing myopic shift between 36 months after surgery and their final recorded refraction. The main complications were amblyopia, especially in unilateral cataracts, and posterior capsular opacification. Amblyopia was most probably related to a combination of early onset of dense cataract in this young age group, late presentation for initial surgery, delay in capsulotomies, and imperfect compliance with a rigorous occlusion regime. CONCLUSION: Intraocular lens implantation in infants less than 1 year of age is generally a safe procedure. The spread of final refractive error was very wide. Final refraction in the unilateral group was significantly more myopic than the bilateral group. Final acuities were often disappointing especially in the unilateral group.

Amblyopia↗
PubMedDate not supplied

Age-related refractive shifts in simple myopia.

BACKGROUND: An understanding of physiologic age-related shifts in myopic refractive errors is important to the refractive surgeon for the interpretation of long-term results, surgical planning, and patient counseling. This study characterizes the refractive stability of adult simple myopia with a retrospective study of 413 eyes. METHODS: Approximately 74,000 patient records were analyzed to identify 208 adults with -1.00 to -6.00 diopters (D) of myopia who were followed for more than 20 years at the Spokane Eye Clinic. Amounts of myopic shift (increase in myopia) and hyperopic shift (decrease in myopia) were identified and analyzed within the population. The results were compared to long-term studies of radial keratotomy. RESULTS: The mean changes per patient age decade were: 20s, -0.60 D; 30s, -0.39 D; 40s, -0.29 D; 50s, +0.28 D; 60s, +0.41 D. Reanalyzed Prospective Evaluation of Radial Keratotomy (PERK) study 10-year postoperative data demonstrated progressively increasing hyperopic shifts per decade, at least to age 50. CONCLUSION: The normal adult population with simple myopia differs from the general population and consists of a population subgroup that is relatively stable and other subgroups that experience significant refractive shift. The hyperopic shift after radial keratotomy appears to be surgically induced and may be larger than previously thought.

Adult↗
PubMed1987

Combined penetrating keratoplasty, extracapsular cataract extraction, and posterior chamber intraocular lens implantation.

We reviewed 22 cases of triple procedure in the last two years at our institution. Six months postoperatively 21 of the 22 transplanted corneas were clear. One graft for herpetic corneal scarring failed. Best corrected visual acuity was 20/40 or better in 14 patients. The average refractive error was--1.31 +/- 2.30 diopters. Refractive astigmatism was 4 diopters or less in 80% of patients. These results, which compare favorably with previous series, indicate the efficacy and safety of this procedure.

Cataract Extraction↗
PubMed2006

Contact lens wear and IOL power calculation before cataract surgery: a cautionary tale.

PURPOSE: To present a case of erroneous corneal measurements, which led to inaccurate predicted intraocular lens (IOL) power. METHODS: A 60-year-old woman underwent preoperative assessment for cataract surgery. The predicted IOL power was 19.5 D. RESULTS: Repeated biometry led to different measurements and an 11.0-D powered IOL was inserted. The predicted IOL power was incorrect, as the patient had worn contact lenses during the preoperative assessment. CONCLUSIONS: This case demonstrates that errors can occur, and it is essential to fully understand the principles of biometry and the refractive issues of cataract surgery to avoid postoperative refractive errors.

Cataract Extraction↗
PubMed1980

Refractive power of premature children at infancy and early childhood.

We evaluated the refraction of 198 children born prematurely with birth-weights of 2,000 g or less, without any ocular disease. Between the ages of 6 months to 3 1/2 years these children had a mild hypermetropia. The refractive error did not change between the ages of 6 months and 3 1/2 years. The refraction of the prematurely born children was similar to that found in children born at full term.

Age Factors↗
PubMed2003

Kersley lecture: eye believe in contact lenses: contact lenses and/or refractive surgery.

PURPOSE: Media publicity has made patients increasingly aware that surgical vision correction is available. This article gives an overview on refractive surgery and contact lenses. METHODS: Contact lens and refractive surgery possibilities are highlighted for patients with myopia, hyperopia, astigmatism, presbyopia, aphakia, and keratoconus. Therapeutic, pediatric, and cosmetic indications are discussed. RESULTS: Refractive surgery is beneficial for low refractive errors. The use of contact lenses is mandatory in cases of monovision and strabismus before refractive surgery and beneficial for therapeutic use postoperatively. CONCLUSION: Although many patients are always best corrected with contact lenses, only the right synergism of contact lenses and refractive surgery will benefit patients.

Contact Lenses↗
PubMed1981

The accuracy of multimeridional refraction.

The accuracy of meridional refraction using equally spaced preselected meridians was investigated by using populations of computer-simulated patients. The number of meridians refracted, patient refractive error, and the coarseness of phoroptor steps were varied. Results indicate that the accuracy of meridional refraction is independent of the relative orientation of the axis of the patient's astigmatism and the preselected meridians, that little is to be gained by use of a phoropter with steps finer than the usual 0.25 D, and that with a sufficient number of meridians, meridional refraction can be as accurate as more conventional techniques.

Computers↗
PubMed1988

Refractive changes from use of silicone oil in vitreous surgery.

When silicone oil fills the vitreous cavity of the phakic eye or the entire aphakic eye, the refractive correction can be expected to change by 5-9 diopters and sometimes as much as 14 diopters. Aphakic eyes become less hyperopic when filled with silicone oil, whereas phakic eyes become more hyperopic when the vitreous cavity is filled with silicone oil. Previously emmetropic aphakic eyes that are filled with silicone oil have only 4-6 diopters of hyperopia, whereas the same eyes have 10-12 diopters of hyperopia before insertion or after removal of silicone oil. Phakic eyes develop 5-7 diopters of hyperopia when the vitreous cavity is filled with silicone oil, and this puts them in the same range as the silicone oil filled aphakic eyes. High myopia, incomplete silicone oil filling, and several other factors influence the final optical outcome. The vitreoretinal surgeon must anticipate significant changes in refractive error when silicone is introduced into an eye or removed from the eye. Careful retinoscopy and refraction is essential for obtaining optimal vision in these patients.

Adult↗
PubMed1980

Depth-of-focus of the pseudophakic eye.

Pseudophakic patients have been found with the ability to read both 6/6 and N5 without a reading addition. An explanation of this phenomenon is offered in terms of the depth-of-focus of the pseudophakic eye. Results of experiments to measure the depth-of-focus of the pseudophakic eye for Snellen letters are compared with theoretical predictions from earlier work, and implications in terms of visual acuity and refractive error are discussed.

Cataract↗
PubMedDate not supplied

A quality of life comparison of people wearing spectacles or contact lenses or having undergone refractive surgery.

PURPOSE: To demonstrate the use of the Quality of Life Impact of Refractive Correction (QIRC) questionnaire for comparing the quality of life of pre-presbyopic individuals with refractive correction by spectacles, contact lenses, or refractive surgery. METHODS: The 20-item QIRC questionnaire was administered to 104 spectacle wearers, 104 contact lens wearers, and 104 individuals who had undergone refractive surgery (N = 312). These groups were similar for gender, ethnicity, socioeconomic status, and refractive error. The main outcome measure was QIRC overall score (scaled from 0 to 100), a measure of refractive correction related quality of life. Groups were compared for overall QIRC score and on each question by analysis of variance, adjusted for age, with post hoc significance testing (Sheffé). RESULTS: On average, refractive surgery patients scored significantly better (mean QIRC score 50.2 +/- 6.3, F(2,309) = 15.18, P < .001) than contact lens wearers (46.7 +/- 5.5, post hoc P < .001) who were in turn significantly better than spectacle wearers (44.1 +/- 5.9, post hoc P < .01). Convenience questions chiefly drove the differences between groups, although functioning, symptoms, economic concerns, heath concerns, and well being were also important. Spectacle wearers with low strength prescriptions (46.18 +/- 5.05) scored significantly better than those with medium strength prescriptions (42.74 +/- 6.08, F(2,190) = 3.66, P < .05, post hoc P < .05). A small number (n = 7, 6.7%) of refractive surgery patients experienced postoperative complications, which impacted quality of life (37.86 +/- 2.13). CONCLUSIONS: Quality of life was lowest in spectacle wearers, particularly those with higher corrections. Contact lens wearers had significantly better QIRC score than spectacle wearers. Refractive surgery patients scored significantly better than both. However, this was accompanied by a small risk of poor quality of life due to postoperative complications. The QIRC is an effective outcome measure for quality of life impact of refractive correction.

Adolescent↗
PubMed2001

General binocular disorders: prevalence in a clinic population.

The purpose of this paper was to study the prevalence of nonstrabismic accommodative and binocular dysfunctions in a clinical population. We examined 265 symptomatic patients who were chosen from an optometric clinic. We performed several tests to diagnose any form of refractive, accommodative or binocular dysfunction. Of the 265 subjects examined, 59 patients (22.3%) had some form of accommodative or binocular dysfunction and required not just the correction of the refractive error but a specific treatment for each of the problems diagnosed. The remaining subjects were classed as having refractive anomalies. The frequency of binocular dysfunctions was 12.9%, and 9.4% for accommodative anomalies. Convergence excess (4.5%) was more prevalent than convergence insufficiency (0.8%) and accommodative excess (6.4%) more prevalent than accommodative insufficiency (3%).

Accommodation, Ocular↗
PubMed1988

Lens implant exchanges for incorrect power: results of an informal survey.

Despite the introduction of ultrasonic axial length measurements and a variety of intraocular lens implant prediction formulas, postoperative predicted errors greater than 2 diopters occur in approximately 5% to 10% of lens implantations, and occasional errors of 5 diopters to 7 diopters or greater are still encountered. An informal survey revealed successful lens implant exchanges for initial postoperative refractive errors of +4.37 to -14.00 diopters in eight eyes.

Eye Diseases↗
PubMedDate not supplied

Avoiding refractive problems in cataract surgery.

A good visual result after cataract surgery and intraocular lens implantation depends on preoperative determination of an "ideal" postoperative refraction. This will depend on the refractive error in the other eye and whether the cataract is monocular or binocular. Methods are outlined for calculating the postoperative refraction and refracting the pseudophakic patient after surgery.

Cataract Extraction↗
PubMed1988

Simple retinoscopic screening.

A simplified retinoscopic technique to screen for refractive errors in children is presented. The technique described was assessed in 98 children and the results correlated with full retinoscopic refractions. All tests were done with cycloplegia. Orthoptists' results using the simple retinoscopy compared well with the full retinoscopic findings of the ophthalmologists, with an overall sensitivity of 90% and specificity of 74%. These results compare favourably with more technical refractive screening methods. This technique may be suitable as an adjunct to vision screening in pre-school children.

Child↗
PubMed1981

The eyes of young chickens grow toward emmetropia.

The distribution of refractive errors was followed in chicks from hatching to 8 weeks of age. A dramatic progressive decrease in the variability of refractions was observed over this period. In addition, there appeared to be a parallel decline in hyperopia, even when the artifactual hyperopia of retinoscopy was taken into account. These results are evidence for a postnatal development regulatory mechanisms, most likely dependent on vision, which directs growth of the eye toward emmetropia.

Animals↗