Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “refractive error”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 955 records · Page 53Linked to original sources
PubMed2003

Prevalence of myopia among primary school children in eastern Sydney.

BACKGROUND: Worldwide there is concern that the prevalence of myopia is increasing but the prevalence of myopia in Australian school children has not been analysed in detail. This study examines the prevalence of refractive errors in a large unselected population of primary school children in the eastern suburbs of Sydney. METHODS: Children visiting the Vision Education Centre at the School of Optometry and Vision Science, University of New South Wales, on a school excursion during the first half of the 1990s were refracted by non-cycloplegic retinoscopy. Spherical equivalents were computed and analysis of variance carried out. RESULTS: There were 1,459 boys and 1,076 girls in the study, a total of 2,535 children of whom approximately 40 per cent were born overseas or were first generation Australians. Overall, there was no significant difference in refractive error between girls and boys, although there were age/gender interactions with older girls exhibiting more hyperopia than boys. The refractive error ranged from -0.25 to +1.25 D spherical equivalent in 87.3 per cent of children. Mean spherical equivalent for the group was +0.50 +/- 0.82 D. There was a significant shift (p < 0.001) towards increasing myopia with age. The prevalence of myopia greater than -0.50 D rose from 1.0 per cent of four-year-olds to 8.3 per cent of 12-year-olds. CONCLUSIONS: The prevalence of myopia found in a large multi-ethnic group of non-clinical primary school children in eastern Sydney is lower than expected from other studies in the USA and Asia. Compared with Australian data from the 1970s and 1980s, only a weak increase in the prevalence of myopia is revealed.

Age Distribution↗
PubMed2004

Accuracy of noncycloplegic autorefraction in school-age children in China.

PURPOSE: To evaluate the accuracy of noncycloplegic autorefraction in a representative sample of school-age children in China. METHODS: Refractive error was measured with an autorefractor, both before and after cycloplegia induced with cyclopentolate, in a population-based sample of 4973 children between the ages of 7 and 18 years. Spherical equivalent refractive error and astigmatism as represented by Jackson crossed-cylinders (J0 and J45) were the main outcome measures. RESULTS: Noncycloplegic measurements of equivalent spheres were consistently more negative or less positive than those after cycloplegia, with mean +/- SD differences of -1.23 +/- 0.97 D. The differences were particularly large for hyperopic eyes (mean difference of -2.98 +/- 1.65 D for hyperopia of at least +2.00 D) while becoming progressively smaller for emmetropic eyes, and smaller yet for myopic eyes (mean difference of -0.41 +/- 0.46 D for myopia of -2.00 D or more). Increasing age was associated with increased, but clinically insignificant, differences. Little difference was found between noncycloplegic and cycloplegic measurements of astigmatism: mean J0 and J45 differences were -0.08 +/- 0.13 D and -0.01 +/- 0.09 D, respectively. CONCLUSIONS: Noncycloplegic autorefraction was found to be highly inaccurate in school-age children and, thus, not suitable for studies of refractive error or for prescription of glasses in this population.

Adolescent↗
PubMedDate not supplied

Treatment of hypotony maculopathy after trabeculectomy.

BACKGROUND AND OBJECTIVE: To determine if resuturing of the scleral flap to increase IOP in the post-trabeculectomy eye is an effective treatment of hypotony maculopathy. PATIENTS AND METHODS: The medical records of nine consecutive patients who developed visual acuity loss after trabeculectomy related to hypotony maculopathy were reviewed to determine factors that contribute to successful restoration of visual acuity. The average age of the patients was 50 years and average refractive error was -4.25 diopters (D). Mean Snellen visual acuity dropped from 20/25 to 20/200 after the onset of hypotony. RESULTS: Six of nine eyes recovered visual acuity to within one line of initial level after treatment of the hypotony. Four of these six eyes underwent resuturing of the scleral flap to reverse the excess filtration within 6 months of the onset of hypotony maculopathy. Five of these six patients had final vision of 20/30 or better. The mean phakic preoperative refractive error in these six eyes was -2.25 D, compared with a mean refractive error of -8.50 D in the three eyes with persistent visual loss (P = 0.002). After reversal of the hypotony, the average peak intraocular pressure in the six eyes with visual recovery was 33 mm Hg, compared with an average peak IOP of 7 mm Hg in the three eyes with persistent visual loss. (P = 0.015) CONCLUSION: Although reversal of the hypotony maculopathy in six eyes was associated with a few weeks of higher than normal IOP, the final IOP was acceptably low. Five of six filtering blebs remained functional with a mean follow-up of 3 years. The final average IOP in the six eyes that were successfully treated was 12.7 mm Hg. In this series of patients, visual acuity was restored to eyes with hypotony maculopathy by increasing the IOP to higher than normal levels.

Adult↗
PubMed2005

Myopia progression is specified by a double exponential growth function.

PURPOSE: The purpose of this study was to demonstrate how well a modified Gompertz double exponential growth function delineates the diverse courses of myopia progression found in individual eyes. The function is: R = Re + Rc(0.07295)(a(x - t0)) where the spherical equivalent refractive error at a given age R equals the initial refractive error (Re) plus the overall refractive change (Rc) times a double exponential function with the base (0.07295) representing the proportion of Rc that occurs when maximum acceleration is reached, a is a curvature coefficient, t0 is the age of onset and x is age. METHODS: This function was fit to longitudinal refractive data (spherical equivalents) for both eyes of 36 myopic children. The fits were required to meet a stringent set of criteria, including fitting transitions in and out of myopia progression and having no systematic errors or arbitrary constants. RESULTS: Correlation between values on the refractive function and corresponding data of individual eyes is high (mean r = 0.973 +/- 0.020), the sum of squares between the data and function is low, and all other criteria are met. The rates of refractive change and acceleration were derivable from this function. It has been shown that, if peak acceleration rate is used as a criterion for the onset of myopia progression, then myopization onset starts a year earlier (mean = 8.93 years) than when a -0.50-D onset criterion is used (mean = 9.93 years), and it usually starts before the spherical equivalent reaches zero (mean R = +0.09 D). Age of onset is highly correlated with the duration of myopia progression (r = 0.693), which in turn is correlated with the amount of myopia achieved (r = 0.443). CONCLUSIONS: We demonstrate that the double exponential function delineates the dynamics of myopia progression onset, offset, and the derivatives that describe the mechanisms underlying the growth process that causes myopia and have explained the advantages of this function. The function can be used to more accurately portray the course of individual subject's myopic progression.

Adolescent↗
PubMed2006

Photodynamic therapy with verteporfin for subfoveal choroidal neovascularization secondary to pathologic myopia: long-term study.

PURPOSE: To assess the safety and effectiveness of photodynamic therapy (PDT) with verteporfin for subfoveal choroidal neovascularization (CNV) secondary to pathologic myopia (PM). METHODS: Sixty-two patients (62 eyes) with PM underwent PDT according to the guidelines of the Verteporfin in Photodynamic Therapy Study. Clinical evaluations performed at all study visits included measurement of best-corrected Snellen visual acuity, slit-lamp biomicroscopy, and fundus fluorescein angiography. Patients were followed up at 1 month and 3 months after treatment and thereafter at 3-month intervals. RESULTS: The final visual acuity of the study patients, after a median follow-up of 31 months, improved by >or=1 Snellen lines in 8 patients (13%), deteriorated in 20 (32%), and remained stable in 34 (55%). The baseline visual acuity was similar in the various study groups. The final mean visual acuity in group A (55 years of age or younger) was 20/80 and significantly (P=0.006) better than that (20/138) in group B (older than 55 years of age). The mean final visual acuity in eyes with higher refractive error at baseline (greater than -17 diopters) was significantly better (P=0.014) than that in eyes with lower refractive error (-6 to -10 diopters). CNV size did not affect visual outcomes. CONCLUSION: PDT preserves vision in patients with CNV associated with PM. Younger patients and eyes with higher refractive error appear more likely to benefit from PDT with verteporfin.

Adult↗
PubMed2004

Vision in athletes with intellectual disabilities: the need for improved eyecare.

BACKGROUND: Special Olympics provides sporting opportunities for people with intellectual disabilities (ID), and Lions Clubs International Opening Eyes GB offers vision screening for athletes at Special Olympics Games. METHODS: Opening Eyes GB screened the vision of 505 UK athletes at its inaugural event in 2001. The results were analysed and are presented here. RESULTS: Results showed that athletes do not differ from other people with ID in being at high risk of ocular and visual defects and many are not accessing eyecare. 15% reported never having an optometric eye examination, and yet 19% of these athletes had a significant refractive error, 32% had ocular anomalies and 6% were visually impaired. Overall, findings confirmed the high prevalence of refractive errors and strabismus amongst people with ID. 40% of athletes had ocular abnormalities, including 15.6% with blepharitis, a readily treatable condition that causes discomfort. 9% had lens opacities, of which half were probably impairing sight. An important finding was that many athletes have reduced vision and 14% could be classified as visually impaired (WHO definition) even when refractive errors were fully corrected. CONCLUSIONS: Special Olympics athletes should be encouraged to have regular eye examinations (as indeed, should all people with ID), and educators, carers and coaches need appropriate information about the visual status of their charges.

Adolescent↗
PubMed2004

School vision screening, ages 5-16 years: the evidence-base for content, provision and efficacy.

The optometric profession in the UK has a major role in the detection, assessment and management of ocular anomalies in children between 5 and 16 years of age. The role complements a variety of associated screening services provided across several health care sectors. The review examines the evidence-base for the content, provision and efficacy of these screening services in terms of the prevalence of anomalies such as refractive error, amblyopia, binocular vision and colour vision and considers the consequences of their curtailment. Vision screening must focus on pre-school children if the aim of the screening is to detect and treat conditions that may lead to amblyopia, whereas if the aim is to detect and correct significant refractive errors (not likely to lead to amblyopia) then it would be expedient for the optometric profession to act as the major provider of refractive (and colour vision) screening at 5-6 years of age. Myopia is the refractive error most likely to develop during primary school presenting typically between 8 and 12 years of age, thus screening at entry to secondary school is warranted. Given the inevitable restriction on resources for health care, establishing screening at 5 and 11 years of age, with exclusion of any subsequent screening, is the preferred option.

Adolescent↗
PubMed1998

Clinical course of accommodative esotropia.

PURPOSE: To report the clinical course of patients having accommodative esotropia and to determine whether the strabismus resolves during the adolescent years. METHODS: Patients diagnosed with accommodative esotropia from 1983 to 1991 were recalled to the clinic for re-examination. For all patients, the clinical records indicated that the esotropia had begun in early childhood and was controllable at some time during the follow-up period with plus power single vision glasses and/or bifocals. Re-examination included assessment of patient history, visual acuity, ocular alignment, versions, sensory fusion, and refractive error. The ocular alignment status with and without any current plus single vision and/or bifocal correction, and the refractive error at recall, were compared to the same findings taken at the patient's initial clinic visit. These findings were compared to determine whether the accommodative esotropia had resolved, improved, remained the same, or increased in amount. RESULTS: Thirty-nine patients participated in the study. At the time of recall their average age and follow-up period were 16.8 and 9.5 years, respectively. Before treatment, the mean eso deviation was 14.5 delta at distance and 21.6 delta at near. At recall, 15 patients used single vision glasses, 9 used glasses with bifocals, 11 used contact lenses, and 4 patients used no optical correction. Five patients (12.8%) had best corrected acuity in one eye of 20/30 or poorer. Twenty patients (57.1%) were not strabismic with their current refractive correction, whereas 15 patients (42.8%) continued to be esotropic (intermittent or constant) at distance and/or near. When assessing ocular alignment without the current plus power correction, 26 patients (82%) were esotropic and 4 patients (15.6%) were heterophoric. The mean deviation without the optical correction was 18.6 delta at distance and 19 delta at near. Of the 4 patients presenting without an optical correction, 3 were esotropic at distance and/or near and 1 patient was heterophoric. Six patients (15.3%) also had inferior oblique overaction, 2 which occurred with superior oblique palsy. Thirty-three patients (86.8%) fused the Worth dot test at distance and/or near, and 35 patients (89.7%) had stereopsis (mean, 84 sec arc). The mean spherical equivalent refractive error changed for the group from 2.77 D hyperopia at the initial evaluation to 1.95 D hyperopia at recall (mean refractive shift = -0.08 D/year). CONCLUSIONS: Accommodative esotropia persists for most patients into adolescence and early adulthood. These patients need to be carefully monitored during this period because most do not outgrow their hyperopia and some can again become esotropic.

Accommodation, Ocular↗
PubMed1995

Physiological strategies for emmetropia.

PURPOSE: To identify relationships among age-independent ocular biometric variables which contribute to ocular refraction in adult human eyes, and to identify differences in those relationships between emmetropes and ametropes. METHODS: Manifest refraction (DRS methodology), corneal refractive power (keratometry), and axial anterior segment (anterior cornea to posterior lens), vitreous cavity (posterior lens to anterior sclera) and total globe (anterior cornea to anterior sclera) length (A-scan ultrasonography) were determined in 185 unaccommodated right eyes of adult humans aged 18 to 70 years. There were 136 emmetropes with absolute refractive error < or = 2.0 diopter, and 49 ametropes (47 myopes, 2 hyperopes) with absolute refractive error of 2.25-11.0 diopters. RESULTS: Refraction decreased significantly with increasing globe and vitreous cavity length in emmetropes and ametropes. Anterior segment length was also significantly negatively correlated with refraction in emmetropes, but not in ametropes. Corneal refractive power was not correlated with refraction in either group, but decreased significantly with increasing globe length in both, more strongly in emmetropes. Globe and vitreous cavity length were significantly positively correlated in both groups, more strongly in ametropes. Anterior segment length increased significantly with increasing globe length in emmetropes but not in ametropes. Anterior segment length decreased significantly with increasing vitreous cavity length in ametropes but not in emmetropes. CONCLUSION: These findings indicate an "inflatable anterior segment" as well as the classic "inflatable globe" mechanism of emmetropization. This newly described anterior segment mechanism involving increased separation between the cornea and the lens with increasing globe size appears to be absent in adult human myopia.

Accommodation, Ocular↗
PubMed1997

Corneal topography and myopia. A cross-sectional study.

PURPOSE: Central corneal curvature is known to vary with refractive error, but the relation between corneal topography and ametropia is less clear. The current study was conducted to determine whether a relation exists between corneal asphericity and myopia. Associations between corneal asphericity and each of the components of refraction also were examined. METHODS: Corneal asphericity and apical radius of curvature were determined for 113 eyes (spherical equivalent refractive error +0.25 diopter [D] to -9.88 D) by fitting a conicoid equation to videokeratoscopic data. Computerized videokeratoscopic images were recorded using a Topographic Modeling System. Keratometry also was performed on each eye. Anterior chamber depth, lens thickness, vitreous chamber depth, and axial length were measured with a hand-held biometric ruler. RESULTS: A low but statistically significant positive correlation was found between corneal asphericity (Q) and spherical equivalent refractive error (r = 0.275, P < 0.01). Significant relations also were observed between Q and vitreous chamber depth (r = 0.17, P < 0.1) and between Q and axial length (r = 0.24, P < 0.05). The association between Q and corneal radius of curvature was found not to be significant. Eyes with higher levels of myopia had steeper central corneal curvatures, deeper anterior and vitreous chambers, and greater axial lengths. CONCLUSIONS: A tendency for the cornea to flatten less rapidly in the periphery with increasing myopia was shown. Decreased peripheral corneal flattening also was observed in association with increasing vitreous chamber depth and increasing axial length. These findings have implications for refractive surgery outcomes, schematic eye modeling, contact lens design, and ocular aberration analysis.

Adolescent↗
PubMed1999

[Amblyopia without strabismus in context of research on concomitant strabismus].

PURPOSE: To evaluate pathogenic factors for unilateral amblyopia in the group of amblyopic patients without strabismus. MATERIAL AND METHODS: In the study 141 patients with unilateral amblyopia without strabismus were evaluated according to age, sex, visual acuity, refraction error, presence of anisometropia, age of mother on delivery, weight on birth, hereditary transmission of strabismus or refractive error, pregnancy and delivery complications, response to treatment. RESULTS: Serious birth and pregnancy complications were noted only in 14.2% of cases, hereditary transmission might be suspected in 41.2% of patients. Anisometropia was found in 72% of cases. No significant difference in prevalence of possible pathogenic or risk factors such as age, sex, birth-weight, age of mother on delivery, hereditary transmission, pregnancy or delivery complications were found between anisometropic and isometropic group. Anisometropic group had bigger refractive error and deeper amblyopia, but responded better to treatment. CONCLUSION: Etiology of amblyopia without strabismus, particularly in the group of patients with isometropia, should be associated with trauma to central nervous system either in pre-natal or early after birth period.

Adolescent↗
PubMed1999

Chronic open-angle glaucoma and associated ophthalmic findings in monozygotic twins and their spouses in Iceland.

PURPOSE: To determine the concordance of glaucoma and ocular parameters in monozygotic twins and their spouses. METHODS: This was a prospective study that included 50 twin pairs 55 years of age or older and 47 of their spouses. Zygosity was determined by genetic laboratory testing. RESULTS: The concordance of open-angle glaucoma in monozygotic twin pairs was 98.0%, which significantly exceeded that of twin/spouse pairs (70.2%). There was a significant association in mean intraocular pressure (IOP), mean axial length, anterior chamber depth, and refractive error in the twin pairs. However, there was no association between the twins and their spouses for these ocular parameters. Eight twin pairs were found to have pseudoexfoliation syndrome (PXFS), five of which were concordant. There was no association between glaucoma and mean axial length or glaucoma and refractive error in the twin pairs studied. CONCLUSION: The statistically significant higher concordance of glaucoma--and the high correlation of mean IOP, mean axial length, anterior chamber depth, and refractive error--in twin pairs and the lack of association of these factors in twin/spouse pairs strongly suggests the importance of genetic factors for these ocular parameters.

Aged↗
PubMed1995

Visual function in Rett syndrome.

The authors examined refractive error, pattern onset visual evoked potentials, ocular posture and they performed internal and external eye examinations in 11 subjects with Rett syndrome (aged between four and 24 years) and 18 normal controls (aged between six and 20 years). Substantial refractive errors were common in the Rett syndrome group. Spectacle correction had never previously been worn and glasses were provided where appropriate. No subjects had nystagmus or optic nerve pallor and only one was strabismic. All subjects had recognisable and reproducible pattern-onset VEPs and latencies and amplitudes did not differ significantly from those of the controls. All demonstrated VEP thresholds of at least 24'. In contrast to other populations with profound disabilities, people with Rett syndrome have good function of the afferent visual pathways and, in view of their substantial refractive errors, are likely to benefit from spectacle correction.

Adolescent↗
PubMed2006

Peripheral defocus does not necessarily affect central refractive development.

PURPOSE: Recent experiments in monkeys suggest that deprivation, imposed only in the periphery of the visual field, can induce foveal myopia. This raises the hypothesis that peripheral refractive errors imposed by the spectacle lens correction could influence foveal refractive development also in humans. We have tested this hypothesis in chicks. METHODS: Chicks wore either full field spectacle lenses (+6.9 D/-7 D), or lenses with central holes of 4, 6, or 8mm diameter, for 4 days (n=6 for each group). Refractions were measured in the central visual field, and at -45 degrees (temporal) and +45 degrees (nasal), and axial lengths were measured by A-scan ultrasonography. RESULTS: As previously described, full field lenses were largely compensated within 4 days (refraction changes with positive lenses: +4.69+/-1.73 D, negative lenses: -5.98+/-1.78 D, both p<0.001, Dunnett's test, to untreated controls). With holes in the center of the lenses, the central refraction remained emmetropic and there was not even a trend of a shift in refraction (all groups: p>0.5, Dunnetts test). At +/-45 degrees , the lenses were partially compensated despite the 4/6/8mm central holes; positive lenses: +2.63 / +1.44 / +0.43 D, negative lenses: -2.57 / -1.06 / +0.06 D. CONCLUSIONS: There is extensive local compensation of imposed refractive errors in chickens. For the tested hole sizes, peripherally imposed defocus did not influence central refractive development. To alter central refractive development, the unobstructed part in the central visual field may have to be quite small (hole sizes smaller than 4mm, with the lenses at a vertex distance of 2-3mm).

Accommodation, Ocular↗
PubMedDate not supplied

Posterior vitreous detachment: clinical correlations.

BACKGROUND: To evaluate the frequency of, and the factors which are primarily and secondarily associated with, posterior vitreous detachment (PVD), and to correlate the presence of PVD with various demographic and ophthalmic entities. METHODS: The clinical prospective observational cohort study included 1,481 subjects (740 women, 741 men) with a mean age of 63.45 +/- 14.97 years (mean +/- SD; range, 10.3-94.9 years) and a mean spherical equivalent refractive error of +0.68 +/- 2.13 dpt (range, -14.25 to +13.50 dpt). The presence of PVD was assessed by indirect and direct ophthalmoscopy, fundus biomicroscopy and by using a Hruby lens upon pharmacologically dilated pupil. Main outcome measures were frequency of PVD, association with age, refractive error, cataract surgery, diabetes mellitus, arterial hypertension, history of ocular trauma, vitreous hemorrhage, various retinal disorders, nonarteritic anterior ischemic optic neuropathy (AION) and open-angle glaucoma. RESULTS: The occurrence of PVD was significantly correlated with increasing age (p < 0.001), myopic refractive error (p < 0.001), female gender (p < 0.001), and surgical aphakia (p < 0.001). PVD occurred significantly more often bilaterally than unilaterally (p < 0.001). Patients with unilateral PVD were significantly (p < 0.001) younger than the patients with bilateral PVD. PVD was seen significantly (p = 0.038) less frequently in AION than in the remaining study population. The frequency of PVD was lower in eyes with than without diabetic retinopathy (p = 0.095), optic disc neovascularization (p = 0.07) and retinal neovascularization (p = 0.09). There was no significant association between the presence of PVD and macular hole, macular edema, retinal vascular occlusive disorders, age-related macular degeneration and open-angle glaucoma. CONCLUSIONS: These data of a large prospective study of PVD confirm some of the findings of previous smaller and retrospective studies. They also provide new information which may be helpful for the understanding of the pathophysiology of PVD and the role of PVD in the pathogenesis of various retinal and optic disc lesions.

Adolescent↗
PubMed2003

Clinical evaluation of the Shin-Nippon NVision-K 5001/Grand Seiko WR-5100K autorefractor.

PURPOSE: A clinical evaluation of the Shin-Nippon NVision-K 5001 (also branded as the Grand Seiko WR-5100K) autorefractor (Japan) was performed to examine validity and repeatability compared with subjective refraction and Javal-Schiotz keratometry. METHODS: Measurements of refractive error were performed on 198 eyes of 99 subjects (aged 23.2 +/- 7.4 years) subjectively (noncycloplegic) by one masked optometrist and objectively with the NVision-K autorefractor by a second optometrist. Keratometry measurements using the NVision-K were compared with the Javal-Schiotz keratometer. Intrasession repeatability of the NVision-K was also assessed on all 99 subjects together with intersession repeatability on a separate occasion separated by 7 to 14 days. RESULTS: Refractive error as measured by the NVision-K was found to be similar (p = 0.67) to subjective refraction (difference, 0.14 +/- 0.35 D). It was both accurate and repeatable over a wide prescription range (-8.25 to +7.25 D). Keratometry as measured by the NVision-K was found to be similar (p > 0.50) to the Javal-Schiotz technique in both the horizontal and vertical meridians (horizontal: difference, 0.02 +/- 0.09 mm; vertical: difference, 0.01 +/- 0.14 mm). There was minimal bias, and the results were repeatable (horizontal: intersession difference, 0.00 +/- 0.09 mm; vertical: intersession difference, -0.01 +/- 0.12 mm). CONCLUSION: The open-view arrangement of the Shin-Nippon NVision-K 5001 facilitates the measurement of static refractive error and the accommodative response to real-world stimuli. Coupled with its accuracy, repeatability, and capability to measure corneal curvature, it is a valuable addition to objective instrumentation currently available to the optometrist and researcher.

Adolescent↗
PubMed2004

Five-year results of laser in-situ keratomileusis (LASIK) after penetrating keratoplasty.

OBJECTIVE: To study the long-term refractive results of LASIK after penetrating keratoplasty. PLACE: Clinica Barraquer de América. METHODS: Retrospective review of 46 eyes of 38 patients that underwent LASIK for the correction of refractive errors after penetrating keratoplasty. RESULTS: The mean interval between keratoplasty and LASIK was 7 years. The preoperative defocus equivalent refraction (DEQ) was 2.0 to 7.0 D in 56% (26/46) of eyes and 8.0 to 24.0 D in the remaining 20 eyes. Five years after LASIK, DEQ was 1.0 to 7.0 D in all eyes. Seventy-five percent of eyes had a refractive error within 2.00 D of emmetropia. Thirty-two percent had uncorrected visual acuity of 20/40 or better, and 59% of eyes gained more than 1 line of best spectacle-corrected visual acuity at 5 years. Vector analysis showed a success index of 60% at 5 years. The refraction in eyes with keratoconus remained stable. CONCLUSION: LASIK is safe and effective for the correction of refractive errors in eyes that have previously undergone corneal transplantation.

Adolescent↗
PubMed1998

Radial keratotomy learning curve using the American technique.

PURPOSE: To delineate the learning curve for a beginning refractive surgeon using the centrifugal (American) technique. SETTING: Naval Medical Center, San Diego, California, USA. METHODS: The first 100 radial keratotomy (RK) cases (51 patients) of one surgeon, divided into five sequential groups of 20, were retrospectively reviewed. All patients had RK using the American technique. Emmetropia was the goal in all patients. Groups were compared with respect to preoperative refractive status, age, sex, and outcome. Outcomes analysis included visual acuity, refractive error, complications, and enhancement rates. Data were reviewed preoperatively and 1 and 3 months postoperatively. RESULTS: All five groups were age and sex matched. There was no difference in preoperative refractive error among the five groups. Sequential improvement in early postoperative refractive error from a mean of -1.73 diopters (D) +/- 1.00 (SD) (first 20) to 0.45 +/- 0.55 D (last 20) (P < .001) and decreased enhancement rates from 50% (first 20) to 0% (last 20) (P = .002) were statistically significant. Visual acuity at 1 month was 20/40 or better in 47% of patients in Group 1 (first 20), whereas all patients in Group 5 (last 20) had an acuity better than 20/40 (P < .001). There was no significant difference in complication rates among the five groups. CONCLUSION: The results of RK using the American technique can improve significantly with surgeon experience. Enhancement rates decreased with experience, and there was no difference in complication rates during the learning period of one surgeon.

Adult↗