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PubMed1995

Partly accommodative esotropia. Should you overcorrect and cut the plus?

OBJECTIVES: To investigate the long-term motor stability and sensory outcome of patients with partly accommodative esotropia who were overcorrected surgically and in whom the hyperopic correction was reduced postoperatively, and to determine if those results depended on the amount of hyperopia present. DESIGN: A 15-year prospective study that analyzed 5-year outcome. Patients whose esotropia was not initially overcorrected were used as controls. PATIENTS: Of 382 patients who underwent surgery for partly accommodative esotropia, 22 were surgically overcorrected and were followed up for 5 years. RESULTS: Of the eight patients in the study group with 2.5 diopters or less of hyperopia in their fixing eye, seven had good motor alignment compared with four of 14 patients who had more than 2.5 diopters of hyperopia. Ninety-one percent (148/163) of the control patients who had greater than 2.5 diopters of hyperopia maintained good motor alignment 5 years after surgery compared with 29% of the study group patients. This difference was statistically significant. Of the eight study patients with less than 2.5 diopters of hyperopia, five developed good stereopsis compared with one of 14 patients with greater hyperopia. CONCLUSIONS: Surgical overcorrection in patients with partly accommodative esotropia with greater than 2.5 diopters of hyperopia may not be reversible by postoperative reduction in the hyperopic correction. It often is reversible, however, in patients with 2.5 diopters or less of hyperopia.

Accommodation, Ocular↗
PubMed2000

Comparison of optical zones in hyperopic laser in situ keratomileusis: 5.9 mm versus smaller optical zones.

PURPOSE: To compare the results of hyperopic laser in situ keratomileusis (LASIK) with a 5.9 mm optical zone (OZ) with those with smaller zones (4.4 to 5.5 mm). SETTING: Instituto de la Visión, Buenos Aires, Argentina. METHODS: The results of LASIK with a 5.9 mm OZ (147 cases) were compared with those in a previously reported group treated with OZs of 4.4 to 5.5 mm (679 cases). In the 5.9 mm group, 31.3% (46 eyes) had low hyperopia, 46.9% (69 eyes) had moderate hyperopia, and 21.8% (32 eyes) had high hyperopia. In the smaller OZ group, follow-up was 1 month in 79.4% (539 eyes), 3 months in 75.5% (501 eyes), 6 months in 68.5% (465 eyes), and 1 year in 38.3% (260 eyes). The hyperopic population studied was divided into 3 subgroups based on the preoperative spherical equivalents of the manifest refraction: subgroup A, low hyperopia: < or = +2.0 diopters (D); subgroup B, moderate hyperopia: +2.0 to +3.0 D; and subgroup C, high hyperopia: > +3.0 D. The following parameters were measured postoperatively: uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refraction (evolution and distribution), and visual acuity lines gained and lost. RESULTS: The preoperative mean spherical equivalents in the 5.9 mm OZ group were +1.47 +/- 0.41 (SD) (subgroup A); +2.98 +/- 0.41 (subgroup B); and +5.13 +/- 0.61 (subgroup C). In the smaller OZ group, they were +1.31 +/- 0.74, +2.56 +/- 0.28, and +5.28 +/- 0. 69, respectively. At 12 months, the distribution of eyes in the 5.9 mm OZ group with refractions within +/-1.0 D were as follows: subgroup A, 100%; subgroup B, 100%; and subgroup C, 94.2%. In the smaller OZ group, the distributions were 100%, 95.3%, and 71.4%. In the 5.9 mm and the smaller OZ groups, the UCVA was 20/40 or better in 92.0% and 81.8% of eyes, respectively, in subgroup A; 94.6% and 100%, respectively, in subgroup B; and 76.5% and 77.9%, respectively, in subgroup C. The percentage of eyes with 0 +/- 1 line of BCVA 12 months after the procedure was also determined in the 5.9 mm OZ group and compared with the percentages in the smaller OZ group. CONCLUSION: Results of hyperopic LASIK with a 5.9 mm OZ in eyes with low, moderate, and high hyperopia are more stable, predictable, and safe than those in eyes with OZs smaller than 5.9 mm.

Adult↗
PubMed1999

Refractive errors in a black adult population: the Barbados Eye Study.

PURPOSE: To describe the prevalence of refractive errors in a black adult population. METHODS: The Barbados Eye Study, a population-based study, included 4709 Barbados-born citizens, or 84% of a random sample, 40 to 84 years of age. Myopia and hyperopia were defined as a spherical equivalent <-0.5 diopters and >+0.5 diopters, respectively, based on automated refraction. Analyses included 4036 black participants without history of cataract surgery. Associations with myopia and hyperopia were evaluated in logistic regression analyses. RESULTS: The prevalence of myopia was 21.9% and was higher in men (25.0%) than in women (19.5%). The prevalence of hyperopia was 46.9% and was higher in women (51.8%) than in men (40.5%). The prevalence of myopia decreased from 17% in persons 40 to 49 years of age to 11% in those 50 to 59 years of age, but increased after 60 years of age. The prevalence of hyperopia increased from 29% at 40 to 49 years of age to 65% at 50 to 59 years of age, and tended to decline thereafter. A higher prevalence of myopia was positively associated (P < 0.05) with lifetime occupations requiring nearwork, nuclear opacities, posterior subcapsular opacities, glaucoma, and ocular hypertension. Factors associated with hyperopia were the same as for myopia, except for occupation, and in the opposite direction. CONCLUSIONS: High prevalences of myopia and hyperopia were found in this large black adult population. The prevalence of myopia (hyperopia) increased (decreased) after 60 years of age, which is inconsistent with data from other studies. The high prevalence of age-related cataract, glaucoma, and other eye conditions in the Barbados Eye Study population may contribute to the findings.

Adult↗
PubMed1997

Complications of combined radial thermokeratoplasty and incisional keratotomy.

PURPOSE: To report complications of radial thermokeratoplasty (RTK) when used in combination with either radial keratotomy (RK) or astigmatic keratotomy (AK). METHODS: RTK is a technique for the surgical correction of hyperopia and presbyopia. 600 degrees C burns are applied to the peripheral cornea for 0.3 seconds using a specialized cautery probe. The thermal energy generated shrinks stromal collagen and flattens the peripheral cornea. The central cornea is steepened producing a myopic shift. RESULTS: Two patients who had RTK in combination with either RK or AK are reported. Patient 1 was bilaterally hyperopic and presbyopic. The patient had RTK performed on the left eye in an attempt to make that eye myopic. The goal was to allow the left eye to be used for near vision. After RTK, the left eye was significantly overcorrected. The patient then had RK in the left eye which resulted in profound overcorrection with return of hyperopia. Postoperatively, examination revealed gaping of the RK incisions and poor epithelial wound healing. The patient also complained of severe ocular pain. Despite suturing the RK incisions, the eye remained hyperopic. The patient underwent two additional RTK procedures which failed to correct the induced hyperopia. The second patient had induced hyperopic astigmatism after undergoing RK. RTK was then performed to correct the hyperopia. However, the result was a worsening of the astigmatism. Two t-cut astigmatic keratotomies were then performed which improved the astigmatism but subsequently exacerbated the hyperopia. A second RTK procedure was then performed; however, it failed to correct the induced hyperopia. CONCLUSIONS: RTK is an unproved surgical technique for the correction of hyperopia and presbyopia that needs much further evaluation before broad clinical application can be supported.

Cornea↗
PubMed2004

Ketorolac for the regression of myopic LASIK overcorrection.

OBJECTIVE: To determine whether ketorolac (Acular) treatment and other factors influence regression after LASIK-induced consecutive hyperopia. METHODS: Seventy-two eyes of 51 patients who had undergone LASIK for myopia and compound myopic astigmatism and who experienced consecutive hyperopia of at least +0.50 diopters within the first postoperative week were analyzed. The consenting patients were treated with ketorolac (Acular). Data were collected over a period of 2 months. Primary preoperative variables included age, eye, preoperative manifest and cycloplegic refractions, and pachymetry. Postoperative variables included presence of microstriae and treatment with ketorolac. Treatment success was measured as reduction of consecutive hyperopia. RESULTS: Thirty-seven eyes were treated, and 35 eyes were in the control group. Mean start time for treatment with ketorolac was 9 days after surgery (range 3-35 days). Mean treatment time was 24.5 days (range 10-63 days). Both groups were matched for all preoperative variables except for age, including manifest and cycloplegic refraction, eye treated, and pachymetry. Treated patients were on average 9 years older than the control group. There was no significant difference in the overall rate of regression between the 2 groups at the 1-month and 2-month periods. Thicker preoperative corneas in all eyes had a sporadic association with reduction of consecutive hyperopia. CONCLUSIONS: Ketorolac does not improve consecutive hyperopia after LASIK for myopia and compound myopic astigmatism when compared with a matched control group. Pachymetry appears to be a determining factor in the degree of regression experienced after consecutive hyperopia. This finding warrants further investigation.

Adult↗
PubMed1998

[Photorefractive keratectomy in hypermetropia].

PURPOSE: The purpose of this study was to assess the predictability and efficiency of the photorefractive keratectomy in hyperopia. MATERIAL AND METHODS: Thinty-eight eyes of 21 patients with the mean age of 34.6 were included. The eyes were divided into 3 groups according to their hyperopia. Group 1: 14 eyes with hyperopia greater than +7.25 D. Group 2: 13 eyes had hyperopia ranging from +4.25 D to +7.00 D and Group 3: 11 eyes with hyperopia less than or equal to +4.00 D. All of the eyes underwent photorefractive keratectomy procedure with 193 nm argon-fluoride excimer laser (Chiron Technolas) with 10 to 30 Hz repetition rate and 120 mJ/cm2 fluence. The mean follow-up time was 12 months. RESULTS: The mean postoperative refraction was +5.05 +/- 1.25 D. in the group 1, +4.71 +/- 1.23 D. in the groupe 2 and +1.65 +/- 0.93 D in the group 3 at the end of the year. CONCLUSION: As a result, we suggest photorefractive keratectomy is efficient, predictable and safe for correcting hyperopia inferior to +4.00 D.

Adult↗
PubMed2002

Population-based assessment of refractive error in India: the Andhra Pradesh eye disease study.

PURPOSE: To assess the prevalence, distribution, and demographic associations of refractive error in the population of the southern Indian state of Andhra Pradesh. METHODS: From 94 clusters in one urban and three rural areas of Andhra Pradesh, 11 786 persons of all ages were sampled using a stratified, random, cluster, systematic sampling strategy in the Andhra Pradesh Eye Disease Study, a population-based cross-sectional study. A total of 10 293 people underwent an interview and detailed dilated eye examination. Refraction was performed by ophthalmic personnel trained in the study procedures. Objective refraction under cycloplegia was assessed for participants < or = 15 years of age and subjective refraction for those > 15 years of age. Myopia was defined as spherical equivalent worse than -0.50 D and hyperopia as spherical equivalent worse than +0.50 D. RESULTS: In the participants < or = 15 years of age, the prevalence of myopia was 3.19% (95% confidence interval [CI] 2.24-4.13%) and of hyperopia was 62.62% (95% CI 57.10-68.13%). In this age group, myopia increased with increasing age and was more prevalent in the urban study area, and hyperopia prevalence was greater in the participants < 10 years of age. In participants > 15 years of age, the prevalence of myopia was 19.45% (95% CI 17.88-21.02%) and of hyperopia was 8.38% (95% CI 6.91-9.85%). Myopia and hyperopia increased with increasing age. Myopia was more common in males, those with education higher than class 12, those with nuclear cataract, and those living in rural study areas. Hyperopia was more common in females, those with any level of formal education, and those living in the urban area and in the well-off rural study area. CONCLUSIONS: There is significant refractive error in this population. These data on the distribution and associations of refractive error can be useful for the planning of refractive eye-care services.

Adolescent↗
PubMed1999

Refractive errors in an urban population in Southern India: the Andhra Pradesh Eye Disease Study.

PURPOSE: To assess the prevalence, distribution, and demographic associations of refractive error in an urban population in southern India. METHODS: Two thousand five hundred twenty-two subjects of all ages, representative of the Hyderabad population, were examined in the population-based Andhra Pradesh Eye Disease Study. Objective and subjective refraction was attempted on subjects >15 years of age with presenting distance and/or near visual acuity worse than 20/20 in either eye. Refraction under cycloplegia was attempted on all subjects < or =15 years of age. Spherical equivalent >0.50 D in the worse eye was considered as refractive error. Data on objective refraction under cycloplegia were analyzed for subjects < or =15 years and on subjective refraction were analyzed for subjects >15 years of age. RESULTS: Data on refractive error were available for 2,321 (92.0%) subjects. In subjects < or =15 years of age, age-gender-adjusted prevalence of myopia was 4.44% (95% confidence interval [CI], 2.14%-6.75%), which was higher in those 10 to 15 years of age (odds ratio, 2.75; 95% CI, 1.25-6.02), of hyperopia 59.37% (95% CI, 44.65%-74.09%), and of astigmatism 6.93% (95% CI, 4.90%-8.97%). In subjects >15 years of age, age-gender-adjusted prevalence of myopia was 19.39% (95% CI, 16.54%-22.24%), of hyperopia 9.83% (95% CI, 6.21%-13.45%), and of astigmatism 12.94% (95% CI, 10.80%-15.07%). With multivariate analysis, myopia was significantly higher in subjects with Lens Opacity Classification System HI nuclear cataract grade > or =3.5 (odds ratio, 9.10; 95% CI, 5.15-16.09), and in subjects with education of class 11 or higher (odds ratio, 1.80; 95% CI, 1.18-2.74); hyperopia was significantly higher in subjects > or =30 years of age compared with those 16 to 29 years of age (odds ratio, 37.26; 95% CI, 11.84-117.19), in females (odds ratio, 1.86; 95% CI, 1.33-2.61), and in subjects belonging to middle and upper socioeconomic strata (odds ratio, 2.10; 95% CI, 1.09-4.03); and astigmatism was significantly higher in subjects > or =40 years of age (odds ratio, 3.00; 95% CI, 2.23- 4.03) and in those with education of college level or higher (odds ratio, 1.73; 95% CI, 1.07-2.81). CONCLUSIONS: These population-based data on distribution and demographic associations of refractive error could enable planning of eye-care services to reduce visual impairment caused by refractive error. If these data are extrapolated to the 255 million urban population of India, among those >15 years of age an estimated 30 million people would have myopia, 15.2 million hyperopia, and 4.1 million astigmatism not concurrent with myopia or hyperopia; in addition, based on refraction under cycloplegia, 4.4 million children would have myopia and 2.5 million astigmatism not concurrent with myopia or hyperopia.

Adolescent↗
PubMed1999

Comparison of objective and subjective refraction before and after laser in situ keratomileusis.

PURPOSE: To compare the accuracy and reliability of objective and subjective refractions before and after laser in situ keratomileusis (LASIK) for myopia, hyperopia, and astigmatism. SETTING: Augenchirurgie und Laserzentrum Hochrum, Innsbruck, Austria. METHODS: In this prospective study, the objective refraction obtained with the Nidek AR-K 900 autorefractor was compared with the subjective refraction in 159 eyes (125 with myopia and 34 with hyperopia) operated on with 2 different lasers. Refractions were done before and 6 months after LASIK. RESULTS: Preoperatively, the objective and subjective refractions correlated better in eyes with low myopia than in those with high myopia (P < .01). Postoperatively, objective refraction was less accurate and reliable than preoperatively. The difference between the objective and subjective spherical refractions was statistically significant (P < .0001) after LASIK in eyes with hyperopia. The correlation between the objective and subjective cylindrical refractions was stronger preoperatively. Especially after LASIK for hyperopia, the objective refraction did not reliably assess the magnitude and axis of the cylinder. The preoperative refractive error did not significantly affect the preoperative and postoperative difference between the objective and subjective refractions or the change between the preoperative and postoperative mean differences. The type of excimer laser used significantly affected the difference between the objective and subjective refractions. CONCLUSIONS: Especially after LASIK for hyperopia, the objective refraction determined with the Nidek AR-K 900 autorefractor delivered erroneous results, which have implications for postoperative care and preoperative measurements for ocular surgery such as enhancement procedures or cataract surgery.

Adult↗
PubMed2004

Contact lens assisted pharmacologically induced keratoshaping.

PURPOSE: To retrospectively evaluate the effectiveness and describe the process of reducing hyperopia with a nonsteroidal antiinflammatory agent and a soft disposable contact lens in postoperative excimer laser patients with consecutive hyperopia. SETTING: Private practice. METHODS: This study includes a retrospective analysis of 14 eyes of 12 patients who underwent laser in situ keratomileusis or photorefractive keratectomy and experienced consecutive hyperopia. Patients were treated with a tightly fit, extended-wear contact lens in combination with the use of ketorolac tromethamine 0.5% (Acular) in an attempt to steepen the cornea. Uncorrected visual acuity, manifest refraction, and slitlamp examination were performed on a weekly basis until the desired outcome was achieved or until treatment was discontinued. RESULTS: A total of 78.57% of eyes experienced a decrease in consecutive hyperopia (>or=0.50 diopters [D]) (P = 0.002). The mean dioptric change was 1.05D. A total of 88.89% of eyes experienced an increase in uncorrected visual acuity (>or=1 line) (P < 0.001). The mean increase was three lines of Snellen or Jaeger acuity. The mean number of weeks to see an effect was 1.71 weeks, and the mean number of weeks to achieve endpoint was 8.29 weeks (median, 6 weeks). CONCLUSIONS.: Contact lens-assisted pharmacologically induced keratoshaping is an effective treatment option for patients who experience consecutive hyperopia after laser in situ keratomileusis or photorefractive keratectomy.

Adult↗
PubMed2004

Corneal asphericity change after excimer laser hyperopic surgery: theoretical effects on corneal profiles and corresponding Zernike expansions.

PURPOSE: To determine the theoretical relationships between the changes in corneal paraxial power, asphericity, and the corresponding Zernike polynomial expansion after conventional and customized excimer laser correction of hyperopia. METHODS: The initial corneal profile was modeled as a conic section of apical radius of curvature R1 and asphericity Q1. The theoretical value of the postoperative apical radius of curvature R2 was computed by using a paraxial formula from the value of R1 and hyperopic defocus D. The postoperative asphericity Q2 of the corneal surface was computed within the optical zone of diameter S after the delivery of a Munnerlyn-based profile of ablation for hyperopia using conic section-fitting and minimization of the squared residuals. These calculations were repeated for different values of defocus, initial apical radius of curvature, and asphericity. Taylor series expansions were also used to provide an approximation aimed at predicting change in asphericity. The coefficients of a Zernike polynomial expansion of the rotationally symmetrical corneal profile (defocus C2(0), spherical aberration C4(0), secondary spherical aberration C6(0)) were also computed, by using scalar products applied to the considered corneal profile modeled as a conic section and were expressed as a function of both its apical radius and asphericity. This allowed approximation of the variations of the Zernike polynomial expansion of the corneal profiles by subtracting the postoperative coefficient weighting a particular aberration from that of the preoperative one in different theoretical situations, after both conventional and customized hyperopia treatments aimed at controlling the postoperative corneal asphericity and delivered over a normalized pupil diameter. RESULTS: Conical least-squares fitting was unambiguous, allowing approximation of the postoperative corneal profile as a conic section of apical radius R2. After a Munnerlyn-based hyperopia treatment, the sign of the asphericity of this profile remains theoretically unchanged, but its value decreased for initially oblate and increased for initially prolate corneas, respectively. A similar trend was noted with the approximation obtained by the Taylor series expansion. The alteration of the apical radius and/or of the asphericity of the corneal surface resulted in variations of both the corneal profile Zernike coefficients C2(0) and C4(0). The former was essentially dependent on the variation of the apical radius and the latter essentially on the variation of both apical radius and asphericity. CONCLUSIONS: Conventional and customized profiles of ablation for hyperopia alter the postoperative corneal asphericity and the Zernike coefficients of the corneal profile. The results of this study may be useful in the interpretation of the postoperative variations of the corneal profile and their impact on corneal wavefront expansion variations after both conventional and customized profiles of ablation.

Cornea↗
PubMedDate not supplied

Results and complications of laser in situ keratomileusis by experienced surgeons.

PURPOSE: To identify intraoperative and early postoperative adverse events and complications that may be encountered after the laser in-situ keratomileusis (LASIK) learning process. METHODS: One hundred sixty-nine consecutive eyes of 108 patients who had LASIK by a surgeon experienced in LASIK were studied. All intraoperative and early postoperative adverse events and complications were noted. Patients were examined at 1 day and 1 to 3 months after surgery. Six baseline refractive groups were studied: high myopia with astigmatism (-10.25 to -17.50 D; 18 eyes), moderate myopia with astigmatism (-6.00 to -9.50 D; 31 eyes), low myopia with astigmatism (-0.75 to -5.87 D; 81 eyes), mixed astigmatism (-0.25 to +0.50 D; 6 eyes), low to moderate hyperopia with astigmatism (+1.00 to +3.75 D; 19 eyes), and high hyperopia with astigmatism (+4.25 to +7.37 D; 12 eyes). Seventy-eight percent (132 eyes) had a primary LASIK procedure; 22% (37 eyes) had LASIK after previous refractive surgery. Primary and secondary LASIK procedures were analyzed together. The Nidek EC-5000 or the Chiron PlanoScan excimer lasers were used. RESULTS: The most commonly observed adverse intraoperative events were minor corneal bleeding (3%) and thin flap (1%). The most commonly observed postoperative events were punctate epithelial keratopathy (6%) and small epithelial defect 1 day after surgery (5%). The most serious complication occurred in three eyes with preoperative high hyperopia (spherical equivalent refraction greater than +4.00 D) in which corneal topographic abnormalities resulted. At last examination, mean postoperative spherical equivalent refraction was less than +1.00 D in all groups. Spectacle-corrected visual acuity was 20/20 in 70 eyes (41%) and 20/25 or better in 119 eyes (70%). Loss of spectacle-corrected visual acuity of two or more lines occurred in five eyes (3%), three of which had preoperative high hyperopia with abnormal postoperative corneal topography. CONCLUSION: Our prospective study should help LASIK surgeons gauge their expectations of intraoperative and early postoperative complications. Surgeons should proceed cautiously when treating patients with high hyperopia, because a higher incidence of loss of spectacle-corrected visual acuity may be encountered postoperatively.

Adult↗
PubMed1999

[Comparison of hyperopic photorefractive keratectomy and LASIK in correction of hypermetropia with excimer laser].

The aim of this work is to compare results of the correction of hyperopia by method of hyperopic photorefractive keratectomy (HPRK) with method of laser assisted keratomileusis known as LASIK. We evaluate group of 129 eyes operated by excimer laser Keracor 117 manufactured by Technolas company. 77 eyes underwent HPRK and 52 eyes hyperopic LASIK (HLASIK). The patients were divided to two groups, the first of which comprised 47 eyes with low hyperopia to +3.5 Dsph and the second 82 eyes with high hyperopia. Follow-up period was 12 months results were statistically evaluated by Student t-test. One year after treatment, in the first group was 62% eyes with hyperopia to +1.0 Dsph after HPRK and 70% after HLASIK. In the second group it was 32% and 44%, respectively. No statistically significant differences have been found between the two groups. In spite of that, we consider HLASIK method better than HPRK from the point of view of stability of results, occurrence of complications and estimated resulting refraction, especially in the eyes with low hyperopia.

Adult↗
PubMed2004

Pseudo-false positive eye/vision photoscreening due to accommodative insufficiency. A serendipitous benefit for poor readers?

BACKGROUND: Children whose eyes and vision are otherwise normal and who should screen negatively as normals, but who fail to compensate for their normal mild hyperopia (i.e. by normally accommodating, or rather actually failing to accommodate) will generate hyperopic crescents in a photoscreen test that can be interpreted as "positive" (for pathology) because high and asymmetric levels of hyperopia are common risk factors for amblyopia. This would therefore usually be considered a "false positive" and no further care would be offered. However, this failure to compensate, may in fact be a pathological disorder, accommodative insufficiency, making this apparently "false positive" situation actually a actually a "false-positive-false- negative positive test", or more simply a "false- false positive test". METHODS: The Alaska Blind Child Discovery Project photoscreened just under 16,000 children referring 6% as "positive", of which, after examination, the false positive rate was just 6% of those referred (0.4% of the total number screened). RESULTS: Ten (42%) of the 24 false positives had evidence of accommodative insufficiency inspite of only average (for age) amounts of cycloplegic hyperopia and a lag of accommodation on dynamic retinoscopy. Eight of the 10 were boys of kindergarten age. Most of these subsequently benefitted from prescription and use of reading glasses of low plus sphere correction. CONCLUSION: About 0.15% of photoscreened children, or 2.5% of those screening positive, and 42% (10/24) found initially on exam to be falsely positive, yielding hyperopic interpretations despite low and usually acceptably normal for age amounts of hyperopia, are in fact suffering from a pathological accommodative insufficiency. Identification of such false- false positives by a combination of photoscreening and dynamic retinoscopy may be used to determine which students might be helped with enforced reading glasses. Confirmatory exams on photoscreen positive-hyperopia cases should include an assessment of accommodation to identify these children.

Accommodation, Ocular↗
PubMed1999

Inheritance of strabismus and the gain of using heredity to determine populations at risk of developing strabismus.

PURPOSE: In the Nordic countries 2 to 4% of the population squint or have been squinting. Since strabismus is one of the major causes of amblyopia early detection and treatment is important for preventing this development. For centuries it has been recognized that strabismus is hereditary. Identifying individuals with a family history of squinting could give access to a risk population for a selective screening. METHODS AND RESULTS: 1,571 children were selected for this study. All children that took part in a voluntary eye examination at one year of age (born 1978-1983) in the city of Vasteras, Sweden and that had a family history of strabismus were selected together with controls. The study was a 6-year follow-up from 1 to 7 years of age. Parental knowledge of squint among relatives and measured high hyperopia (>3.0 D) present at 1 year of age were each and in combination evaluated as a risk indicator for development of strabismus between 1 to 7 years of age. CONCLUSION: The study indicates that a family history of squint in combination with measured high hyperopia can be used in a selective screening to identify a population with an increased risk of 4 to 6 times for developing strabismus. Among the children with parental knowledge of squint among several relatives of both the parents, those with high hyperopia developed strabismus in almost every second case while this was the case in only approximately 10% of those with low hyperopia. Finally, heredity is an important risk indicator that can be used for selective screening purpose. Its potential as a risk indicator is substantially increased when combined with a high hyperopia.

Child↗
PubMed1993

Comparison of cyclopentolate versus tropicamide cycloplegia in children.

This double masked study compares the cycloplegic effects of tropicamide 1% and cyclopentolate 1% in 20 nonstrabismic, nonamblyopic, hyperopic 6- to 12-year-old children with a mean refractive error = +1.48 +/- 1.10 diopters (D). Unlike previous studies which used only amplitude of accommodation to measure the depth of cycloplegia, this study compares refractive error as determined by retinoscopy, distance subjective refraction, and distance autorefraction (Canon R-1). In addition, we compare the amplitude of accommodation as measured by subjective push-up and objective autorefraction methods. There is no statistically significant difference between cyclopentolate and tropicamide for either cycloplegic retinoscopy or distance subjective refraction. Autorefraction measurement of refractive error shows a statistically significant but clinically unimportant bias (0.14 +/- 0.30 D) toward more hyperopia with cyclopentolate. Both drops reveal latent hyperopia, and the mean latencies are not statistically different between the two cycloplegic agents. Latent hyperopia is not systematically related to the degree of hyperopia after tropicamide, but this relation is significant after cyclopentolate. No differences were found between refractive results with either agent at 30 min compared to 60 min after drop instillation. When measured objectively with the autorefractor, accommodation is inhibited more effectively by cyclopentolate than by tropicamide. Our results suggest that although tropicamide is not as effective as cyclopentolate in inhibiting accommodation it is, nevertheless, a useful cycloplegic agent for measuring distance refractive error of low to moderate hyperopia in school-aged children.

Accommodation, Ocular↗
PubMed1999

New refractive surgery procedures in ophthalmology and the influence on Pilot's fitness for flying.

During the last years more and more procedures came up to render people with refractive errors possible to see without contact lenses or glasses. The different procedures for hyperopia, myopia and astigmatism are performed in increasing numbers in hospitals, laser-centres and in private practise. Modern radial keratotomy was introduced in the late 70 by the Russian Fjodorov. Because of the many complications this procedure was replaced by other procedures. Photorefractive keratectomy (PRK) was introduced in 1985, using an excimer laser to vaporize corneal tissue. Because of the side effects as pain and glare and the limited indication area Laser in situ keratomileusis (LASIK) was developed. In this procedure a corneal lamella is cut in, flapped back and the excimer laser vaporize the corneal tissue. These two procedures are mostly applied nowadays. But there are also new techniques that are still in an experimental state. One of that is the implementation of an intrastromal corneal ring that can reduce myopia up to 4 diopters. During the laser thermo keratoplasty 8 to 16 laser applications are performed in the periphery of the cornea to reduce hyperopia up to + 5 diopters. Another refractive surgery procedure is the phakic intraocular lens implantation for high myopia and +3 to +10 diopters hyperopia and the clear lens extraction with intraocular lens implantation for high hyperopia. The Joint Aviation Authority Requirements allow a hyperopia and myopia for commercial pilots of 3 diopters. Some pilot candidates with higher refractive errors undergo refractive surgery. But there are also pilots who are customers of the refractive operating ophthalmologists to get rid of the crutch glasses. This paper gives an overview about the refractive procedures that are performed nowadays on pilots and pilot candidates and gives information about the relevant indications and complications of refractive procedures in the aviation environment.

Adult↗
PubMed1997

Prevalence and risk factors for refractive errors in an adult inner city population.

PURPOSE: To estimate the prevalence of refractive errors among adult black and white Americans and to identify risk factors associated with these refractive errors. METHODS: Refractive error was measured in a population-based sample of black and white adults age 40 or older residing in east Baltimore from 1985 through 1988. Aphakic eyes were excluded from analysis. RESULTS: The prevalence of myopia varied from 10.5% among black men 80 years and older to 42.1% among white women 40 to 49 years of age. Hyperopia ranged from 11.8% among black men 40 to 49 years to 68.1% among white men 80 years of age and older. Astigmatism ranged from 15.8% to 45.2%, and anisometropia ranged from 2.8% to 8.1%, depending on age, race, and gender. Black persons had less myopia, hyperopia, astigmatism, and anisometropia than did white persons. Myopia (< -0.5 diopter [D] spherical equivalent) declined with age, whereas hyperopia (> +0.5 D), astigmatism (> 0.5 D of cylinder), and anisometropia (> 1.0 D between eyes) increased with age. Myopia increased with increasing years of education, although this association was stronger for white persons than for black persons and among younger subjects. Hyperopia declined with increasing years of education, and this association was stronger among younger than older subjects. Education was not associated with astigmatism or anisometropia. CONCLUSIONS: Black persons had lower rates of refractive error than did white persons, except for hyperopia prevalence, which was comparable in black and white women. Refractive errors are common among adult inner city Americans, but rates vary substantially by age, race, gender, and education levels.

Adult↗