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PubMed2002

Refractive error and monochromatic aberrations in Singaporean children.

Higher order optical aberrations were measured in 273 cyclopleged Singaporean school children using a Bausch and Lomb Zywave aberrometer, with 268 of these subjects also undergoing corneal topography measurements (Tomey TMS 2 system). Subjects with low myopia (> -3.00 to -0.50 D) showed slightly, but significantly, less positive levels of spherical aberration than other refractive error groups. Chinese subjects also showed significantly higher amounts of aberrations than Malay subjects, particularly for vertical coma, but also for horizontal coma and spherical aberration. Anterior corneal spherical aberration (calculated from topography) was significantly correlated with whole eye spherical aberration, but did not vary significantly with refractive error or racial background. Residual spherical aberration (i.e. of posterior cornea and crystalline lens) did vary significantly with refractive error and race. Our results do not provide any evidence for aberration-driven form-deprivation as a major mechanism of myopia development.

Child↗
PubMed1998

An infrared eccentric photo-optometer.

An objective infrared optometer has been designed, based on the optical principles of eccentric photorefraction. A CCD camera with an eccentric infrared light source images the subject's pupil through a Badal optometer. The slope of the light distribution across the pupil is continuously recorded. Accommodative state is measured by moving the camera behind the Badal lens until the slope is zero. This position corresponds to the case where the camera is conjugate with the retina of the observer. In this Badal optometer, the irradiance of light at the pupil plane, the sensitivity of the photorefractor, and the focal setting of the camera lens remain constant for all positions of the camera from the eye. The repeatability of a single measure of refractive state in a cyclopleged eye was less than 0.05 D. Static accommodative responses taken from 3 subjects in both closed and open loop conditions provided expected stimulus/response measures. The instrument can also be adapted to measure dynamic accommodation.

Accommodation, Ocular↗
PubMed1999

The refractive development of untreated eyes of rhesus monkeys varies according to the treatment received by their fellow eyes.

To determine the extent to which the visual experience of one eye may influence the refractive development of its fellow eye, we analyzed the data of untreated (UT) eyes of monkeys that received different types of unilateral pattern deprivation. Subjects were 15 juvenile rhesus monkeys, with five monkeys in each of three treatment groups: aphakic eyes with optical correction (AC), aphakic eyes with no correction (ANC), and eyes that were occluded with an opaque contact lens (OC). Under general anaesthesia, refractive error (D) was determined by cycloplegic retinoscopy and axial length (mm) was determined with A-scan ultrasonography. For measurements of refractive error of the UT eyes, there was a significant main effect of groups according to the treatment of the fellow eyes, F(2, 12) = 6.6. While UT eyes paired with AC fellow eyes (mean = +4.2 D) were significantly more hyperopic than the eyes of age-matched normal monkeys (mean = +2.4 D), t(25), = 2.5, UT eyes paired with OC fellow eyes (mean = -0.5 D) were significantly more myopic than the eyes of normal monkeys, t(25) = -9. UT eyes paired with ANC fellow eyes (mean = +1.9 D) were not significantly different from normal eyes. For measurements of axial length there was also a significant main effect of groups, F(2, 12) = 6.9. While UT eyes paired with AC fellow eyes (mean = 16.9 mm) were significantly shorter than the eyes of age-matched normal monkeys (mean = 17.5 mm), t(25) = 2.3, UT eyes paired with OC fellow eyes (mean = 18.1 mm) were significantly longer than the eyes of normal monkeys, t(25) = 2.3. UT eyes paired with ANC fellow eyes (mean = 17.5 mm) were not significantly different from the eyes of normal monkeys. The measurements of axial length and of refractive error of the UT eyes were also significantly correlated with one another, probably indicating that the differences in refractive error were due to differences in axial length, r = -0.8. The present data reveal that despite normal visual experience, UT eyes can have their refractive development altered, systematically, simply as a function of the type of pattern deprivation received by their fellow eyes. These data add to the growing evidence that there is an interocular mechanism that is active during emmetropization. As a consequence, future models of eye growth will need to consider both: (1) the direct influence of visual input on the growing eye; as well as (2) the indirect influence coming from the fellow eye.

Animals↗
PubMed1999

Normal development of refractive state and ocular component dimensions in the marmoset (Callithrix jacchus).

Refractive state and ocular dimensions were studied longitudinally in nine normal marmosets. Animals were anaesthetised and examined (with some exceptions) at 4, 6, 7, 8, 10, 15, 24 and 39 weeks of age. Cycloplegic retinoscopy showed that hyperopia early in life rapidly diminished. Refraction corrected for the artefact of retinoscopy stabilised by 8 weeks of age, but at a slightly myopic value, rather than at emmetropia. The ocular components continued to change throughout the period studied. Corneal radius, measured by photokeratometry, increased slightly during development. Anterior segment depth and vitreous chamber depth (VCD), measured by A-scan ultrasonography, increased throughout development while lens thickness initially increased and then decreased. Data from the eyes of these normal animals were compared with that from the contralateral eyes of animals which received short periods of monocular deprivation early in life (Troilo, D., & Judge S.J. (1993). Ocular development and visual deprivation myopia in the common marmoset (Callithrix jacchus jacchus). Vision Research, 33, 1311-24); eyes which viewed through no lens or a plano lens (Graham, B. & Judge, S.J. (1999)). The effects of spectacle wear in infancy on eye growth and refractive error in the marmoset (Callithrix jacchus). Vision Research, 39, 189-206), and eyes of normal animals in another colony. There were no significant differences between the first two groups and the normal animals in our colony while age-matched animals from the other colony were slightly but significantly less myopic than our animals.

Animals↗
PubMed1999

The growing eye: an autofocus system that works on very poor images.

It is unknown which retinal image features are analyzed to control axial eye growth and refractive development. On the other hand, identification of these features is fundamental for the understanding of visually acquired refractive errors. Cyclopleged chicks were individually kept in the center of a drum with only one viewing distance possible. Defocusing spectacle lenses were used to stimulate the retina with defined defocus of similar magnitude but different sign. If spatial frequency content and contrast were the only cues analyzed by the retina, all chicks should have become myopic. However, compensatory eye growth was still always in the right direction. The most likely cues for emmetropization, spatial frequency content and image contrast, do therefore not correlate with the elongation of the eye. Rather, the sign of defocus was extracted even from very poor images.

Accommodation, Ocular↗
PubMed2000

Ophthalmologic findings in Cohen syndrome. A long-term follow-up.

OBJECTIVE: To determine the nature and course of ophthalmologic abnormalities and their clinical significance in Cohen syndrome. STUDY DESIGN: Observational case series. PARTICIPANTS: Twenty-two Cohen syndrome patients aged 2 to 57 years were examined, and a retrospective review of ophthalmologic records was carried out for 14 of them. All but one were part of the Finnish study of refined mapping of the Cohen syndrome gene by linkage disequilibrium in chromosome 8. MAIN OUTCOME MEASURES: Visual acuity (VA), cycloplegic refraction, biomicroscopy, lens opacitometry, ophthalmoscopy, and fundus photography. RESULTS: With the exception of the two youngest patients, all had symptoms such as nyctalopia, impaired vision, and visual field loss. Progressive, often high-grade myopia, astigmatism, and retinochoroidal dystrophy resembling retinitis pigmentosa occurred in all, except for the youngest patients. The earliest fundus changes were pale disc and pale fundus with or without pigment granularity, followed by narrowed vessels, pigment clumps, and bone spiculelike pigment accumulations by 10 to 20 years of age. Pigment deposits increased and approached the posterior pole by 35 to 40 years of age. Patients more than 45 years of age had severe retinochoroidal atrophy. A bull's-eye macula was seen in most patients. Teenagers had peripheral lens opacities, and young adults had early nuclear sclerosis confirmed by lens opacitometry. Older patients also had posterior subcapsular cataracts, iris atrophy, and iridophacodonesis. Vision started to deteriorate at the age of 6 to 10 years, but remained relatively good (VA 0.5-0.1) in most patients until 30 and, in one case, 46 years of age. Older patients were severely visually handicapped (VA hand motion to light perception), but none were completely blind. CONCLUSIONS: Progressive myopia and retinochoroidal dystrophy are essential features in Cohen syndrome and, together with early lens opacities, lead to deterioration of vision. Cohen syndrome patients need careful ophthalmologic follow-up at all ages. Nyctalopia and restricted visual fields should be considered when planning the patient's daily activities.

Adolescent↗
PubMed2001

The association between nonstrabismic anisometropia, amblyopia, and subnormal binocularity.

PURPOSE: To determine if thresholds exist for the development of amblyopia and subnormal binocularity with various types of anisometropia and to compare these with existing guidelines for the treatment or observation of anisometropia. DESIGN: The records of all previously untreated patients evaluated for isolated refractive error during a 42-month period were reviewed to assess the association between anisometropia, amblyopia, and subnormal binocularity. PARTICIPANTS: Three hundred sixty-one (361) patients with anisometropia and 50 nonanisometropic control participants, examined over a 42-month period, with no history of treatment for refractive error, amblyopia, or other ocular pathologic characteristics were evaluated. METHODS: Uncorrected visual acuity in each eye, monofixation response, and degree of stereopsis were recorded for each patient. Patients with unequal or subnormal uncorrected visual acuity were retested with cycloplegic refraction. If the visual acuity was still abnormal, patients were retested while wearing spectacles. MAIN OUTCOME MEASURES: Degree and type of anisometropia were compared with incidence and severity of amblyopia and subnormal binocularity. RESULTS: Spherical myopic anisometropia (SMA) of more than 2 diopters (D) or spherical hypermetropic anisometropia (SHA) of more than 1 D results in a significant increase in the incidence of amblyopia and decrease in binocular function when compared with nonanisometropic patients (P = 0.05). Increasing levels of SMA and SHA beyond these thresholds result in increased incidence and severity of amblyopia. Cylindrical myopic anisometropia (CMA) or cylindrical hyperopic anisometropia (CHA) of more than 1.5 D results in a significant increase in amblyopia and a decrease in binocular function (P = 0.05). Levels of CMA and CHA more than 1.5 D result in an increased incidence and severity of amblyopia. CONCLUSIONS: This study supports existing guidelines for the treatment or observation of anisometropia and characterizes the association between the type and degree of anisometropia and the incidence and severity of amblyopia and subnormal binocularity.

Adolescent↗
PubMed2001

Refractive changes caused by hypoxia after laser in situ keratomileusis surgery.

OBJECTIVE: To determine whether hypoxia induces refractive changes in subjects who have had laser in situ keratomileusis (LASIK) refractive surgery. DESIGN: Prospective paired eye clinical trial. PARTICIPANTS: There were 20 LASIK subjects (40 eyes) and 20 myopic non-LASIK controls (40 eyes). INTERVENTION: Each subject had one eye exposed to ocular surface hypoxia (humidified nitrogen) by use of an airtight goggle system at sea level for 2 hours. The other eye was simultaneously exposed to humidified, compressed air (21% oxygen) with the same airtight goggle system. MAIN OUTCOME MEASURES: Keratometry, cycloplegic refraction, and pachymetry were compared before and after exposure by use of repeated measures analysis of variance. RESULTS: A significant myopic shift (P: < 0.01) occurred in LASIK corneas exposed to hypoxia compared with myopic control subjects. A significant increase in corneal thickening occurred symmetrically in both LASIK and control subjects exposed to hypoxia. There was a trend toward corneal steepening (keratometry) in LASIK subjects, but this was not statistically significant. CONCLUSIONS: These results suggest that ocular surface hypoxia induces a myopic shift in LASIK subjects.

Adult↗
PubMed2001

Correction of irregular astigmatism with excimer laser assisted by sodium hyaluronate.

PURPOSE: To demonstrate the usefulness of excimer laser surgery assisted by sodium hyaluronate for the correction of irregular astigmatism after previous corneal refractive surgery. DESIGN: Prospective noncomparative case series. PARTICIPANTS: Fifty eyes with surgically induced irregular astigmatism. All the patients had been subjected previously to one or more of the following: laser in situ keratomileusis (LASIK), incisional keratotomy, photorefractive keratotomy, phototherapeutic keratotomy, laser thermokeratoplasty, and corneal trauma. Irregular astigmatism developed thereafter. METHODS: Stability of the corneal topography pattern before surgical decision was observed for at least 6 months with the C-SCAN corneal topography with Ray Tracing (Technomed GmbH, Germany) and the Eye-Sys 2000 Corneal Analysis System (Eye Sys Co., Houston, TX). The lowest pachymetry value was 310 microm in the thinnest portion of the cornea. Ablation was performed with the Technolas 217 C-LASIK excimer laser (Bausch and Lomb Chiron Technolas GmbH, Dornach, Germany), in phototherapeutic keratectomy mode, assisted by a mask of 0.25% sodium hyaluronate. We performed our ablation either on the surface or under a flap, whether elevated or newly cut. MAIN OUTCOME MEASURES: Uncorrected and best-corrected visual acuity, manifest and cycloplegic refraction, superficial corneal surface quality, image distortion, and predicted corneal visual acuity. RESULTS: At 3 months of follow-up, the irregular corneal surface was significantly improved in all cases (n = 50). The superficial corneal surface quality improved from 70.5% +/- 9.16% to 75.6% +/- 10.38 (P < 0.0001). Six eyes lost 1 line of best-corrected visual acuity, three eyes lost 2 lines, and five eyes lost 3 or more lines. The real corneal ablation depth obtained was equal to 63% of that programmed because of the influence of masking substance. Mean uncorrected visual acuity improved from 20/80 +/- 20/125 to 20/63 +/- 20/100 (P = 0.01). Predicted corneal visual acuity improved from a mean of 20/32 +/- 20/80 to 20/25 +/- 20/63 (P = 0.004). Image distortion improved from a mean of 13.95 +/- 3.64 to 12.16 +/- 3.92 (P < 0.0001). We obtained a hyperopic shift in 56% and myopic shift in 40% of eyes. After 6 months of follow-up the irregular corneal surface continued to improve in all cases (n = 32). The superficial corneal surface quality improved from 69.38% +/- 9.48% to 73.13% +/- 8.87 (P = 0.002). Two eyes lost 2 lines of best-corrected visual acuity, and 3 eyes lost 1 line. Ray tracing was significantly improved in all cases at the end of follow-up regarding superficial corneal surface quality (P = 0.002) and the image distortion (P = 0.05). Improvement of predicted corneal visual acuity was not significant (P = 0.11). The procedure proved to be safe, with a safety index of 1.1. Differences between the surface and stromal treatments and between pattern and nonpattern irregular astigmatism were not statistically significant. CONCLUSION: It is possible to produce a more regular corneal surface and to improve best-corrected visual acuity in patients with irregular astigmatism using plano-scan excimer laser assisted by viscous masking solution of 0.25% sodium hyaluronate.

Astigmatism↗
PubMed2001

Two-year outcomes of intrastromal corneal ring segments for the correction of myopia.

OBJECTIVE: To evaluate the safety and efficacy of Intrastromal Corneal Ring Segments (ICRS) for the correction of myopia. DESIGN: Nonrandomized, comparative trial. PARTICIPANTS: Patients enrolled in the United States Food and Drug Administration phase II and phase III clinical trials of the ICRS had best spectacle-corrected visual acuity (BSCVA) of 20/20 or better, myopia of -1.00 to -3.50 diopters (D), and a cylindrical correction of 1.00 D or less as measured by manifest refraction. INTERVENTION: Surgical correction of myopia with an ICRS. MAIN OUTCOME MEASURES: Efficacy was assessed by predictability of refractive outcome (deviation from predicted cycloplegic refraction spherical equivalent), stability of refractive effect, and postoperative uncorrected visual acuity. Safety was assessed by adverse events, maintenance or loss of preoperative BSCVA, and induced manifest refraction cylinder. RESULTS: Four hundred fifty-two patients were enrolled at 11 investigational sites in both studies. Of the 454 surgical attempts, 449 received an ICRS in one eye (0.25, 0.30, and 0.35 mm in 148, 151, and 150 eyes, respectively). First surgeries were attempted in 452 patients. An ICRS was successfully implanted in 447 initial eyes, and 5 surgeries were discontinued. Of the five discontinued surgeries, three patients subsequently exited from the study, and two patients went on to have the ICRS implanted in the second eye, bringing the total number of successful implants to 449 patient eyes. Month 24 postoperative follow-up was completed on 358 patients (80%). At month 24, 328 of 354 eyes (93%) were within +/-1.00 D of predicted refractive outcome. Refraction changed by 1 D or less in 97% of eyes (421/435) between 3 and 6 months after implantation and in 99% (343/348) between months 18 and 24. Before surgery, 87% of eyes (390/448) saw worse than 20/40 uncorrected; 24 months after surgery, 55% of eyes (196/358) saw 20/16 or better, 76% (271/358) saw 20/20 or better, and 97% (346/358) saw 20/40 or better. Although two eyes (2/358; 0.5%) lost two or more lines of BSCVA at 24 months; visual acuity in both was 20/20 or better. Intraoperative complications included anterior corneal surface perforation (three eyes) and anterior chamber perforations (two eyes, one during an attempted exchange procedure); all healed spontaneously without suturing and without loss of BSCVA. The ICRS was repositioned in five eyes to increase correction. Postoperative complications in one eye each were infectious keratitis, shallow segment placement, and loss of two lines of BSCVA at two or more consecutive examinations (subsequently regained). CONCLUSIONS: The ICRS safely, predictably, and effectively reduced or eliminated myopia of -1.00 to -3.50 D. The refractive effect was stable over time.

Adult↗
PubMed2002

Interventions to retard myopia progression in children: an evidence-based update.

TOPIC: To evaluate the efficacy of interventions such as eyedrops, bifocal lenses, or contact lenses in retarding the progression of myopia in myopic children. CLINICAL RELEVANCE: Myopia is a common ocular disorder, and high myopia (myopia at least -6.0 diopters) is associated with potentially blinding conditions. At present, there are no general guidelines on interventions that may decrease myopia progression in children, but some interventions such as contact lenses are offered on an ad hoc basis. METHODS OR LITERATURE REVIEWED: English and non-English language articles published from 1968 to 2000 were retrieved using a keyword search of MEDLINE, Embase, Cochrane Library, and Science Citation Index databases. Randomized controlled trials with comparisons of the effectiveness of interventions to decrease myopia progression in myopic children were reviewed. RESULTS: Ten clinical trials of different interventions to retard myopia progression were reviewed, including three trials that evaluated atropine and one trial that evaluated soft contact lenses. Atropine eye drops of 0.5% concentration were effective in clinical trials, but no significant effect was found for tropicamide or timolol eyedrops. Five of the six trials on bifocal spectacle lenses with various additions failed to show significant retardation, and results of the remaining trial were barely significant (P = 0.047). A trial of soft contact lenses failed to show significant effects. CONCLUSIONS: The latest evidence from randomized clinical trials does not provide sufficient information to support interventions to prevent the progression of myopia. Long-term large-scale double-masked randomized clinical trials, including cycloplegic refraction, are needed before any recommendations about interventions in clinical practice to prevent high myopia in myopic children are considered.

Atropine↗
PubMed2002

Ophthalmic complications of slit-ventricle syndrome in children.

OBJECTIVE: To present the ophthalmic features and visual prognosis of patients with slit-ventricle syndrome (SVS). DESIGN: Observational case series. PARTICIPANTS: Six patients diagnosed and treated with SVS at the Montreal Children's Hospital between 1985 and 1999. METHODS: Patients were included in this study if they had an appropriate ophthalmologic follow-up and if they fulfilled the criteria for the diagnosis of SVS based on intracranial pressure monitoring and neuroimaging studies. MAIN OUTCOME MEASURES: Features studied included patients' baseline ophthalmologic evaluation, visual outcome, and neurosurgical characteristics. RESULTS: The follow-up ranged from 1 to 14 years. The average number of shunting procedures was 3.7. Ocular examination performed on the initial visit revealed a normal visual acuity in four patients, esotropia in three of six patients, and nystagmus in two of six patients. Cycloplegic refraction was normal in all the subjects. Initial funduscopic evaluation revealed optic atrophy in a 4-month-old infant, whereas two children developed optic atrophy later in the course of the disease. One child developed severe visual field defects. The two children with optic atrophy had moderate to severe loss of visual acuity associated with SVS. CONCLUSIONS: A prompt recognition of patients with SVS is crucial, because these individuals are at an increased risk for significant visual loss.

Cerebral Ventricles↗
PubMed2002

A comparison of laser photocoagulation with cryotherapy for threshold retinopathy of prematurity at 10 years: part 2. Refractive outcome.

OBJECTIVE: To compare the refractive outcome of eyes treated with cryotherapy for threshold retinopathy of prematurity (ROP) with eyes treated with laser photocoagulation. DESIGN: Extended follow-up of a randomized controlled clinical trial. PARTICIPANTS: One hundred eighteen eyes from 66 patients were randomly assigned to receive either cryotherapy or laser photocoagulation for threshold ROP. Twenty-five patients (44 eyes treated) were available for follow-up examination 10 years later. INTERVENTION: Cycloplegic autorefraction or retinoscopy was performed. Immersion ultrasound biometry (A-scan) was also performed, and an autokeratometer was used for keratometry. If an A-scan could not be tolerated or the patient was not cooperative, a B-scan through-the-lid biometry was performed. Corneal thickness was measured using optical coherence tomography. MAIN AND SECONDARY OUTCOME MEASURES: Refractive error. In addition, anterior chamber depth, lens thickness, and axial length were measured. Central corneal thickness measurements and keratometric readings were also obtained. RESULT: Eyes treated with cryotherapy were significantly more myopic than those treated with laser photocoagulation. When comparing patients with bilateral treatment, the mean spherical equivalent (SE) of eyes treated with laser was -4.48 diopters (D) compared with a mean SE of -7.65 D for eyes treated with cryotherapy (n = 15 pairs of eyes, P = 0.019). Cryotherapy-treated eyes had a mean axial length of 21.7 mm versus 22.9 mm for laser-treated eyes (P = 0.024, n = 12 pairs of eyes). The anterior chamber depth and lens thickness averaged 2.86 mm and 4.33 mm, respectively, in the cryotherapy-treated eyes compared with 3.42 mm and 3.95 mm in the laser-treated eyes (P < 0.001, n = 12 pairs for both measurements). There were no statistical differences in anterior corneal curvature and central corneal thickness between the two treatment modalities. Crystalline lens power bore the strongest correlation to refractive outcomes in both laser-treated (r = 0.885, P < 0.001) and cryotherapy-treated eyes (r = 0.591, P = 0.026). Although keratometric readings were higher than normal values in these eyes, there was no correlation to the degree of myopia. CONCLUSIONS: Laser-treated eyes were significantly less myopic than cyrotherapy-treated eyes. Lens power seemed to be the predominant factor contributing to the excess myopia.

Anterior Chamber↗
PubMed2002

Ophthalmic findings in fetal anticonvulsant syndrome(s).

PURPOSE: To report the prevalence of ocular abnormalities in a group of children diagnosed with fetal anticonvulsant (FAC) syndrome(s). DESIGN: Retrospective, observational, noncomparative case series. PARTICIPANTS: Forty-six children, age range 8 months to 16 years 5 months (mean, 7 years 1 month), with a confirmed diagnosis of an FAC syndrome. Thirty-seven subjects were exposed in utero to sodium valproate (29 as monotherapy), and the remainder (n = 9) to other anticonvulsants, mainly carbamazepine. METHODS: A total of 46 subjects underwent ophthalmic assessment consisting of visual acuity, cover test, ocular movements, analysis of spectacle lens power, cycloplegic refraction, and anterior segment examination with portable slit lamp, plus direct and indirect ophthalmoscopy. MAIN OUTCOME MEASURES: Refraction and ocular motility status. RESULTS: Thirty-one of 46 (67%) had ocular abnormalities, most commonly errors of refraction (19 of 46; 41%). Myopia was common (14 of 28; 50%) in those exposed to valproate monotherapy and there were high frequencies of strabismus (20%), astigmatism (24%), and anisometropia (11%) in the group as a whole. Thirty-one percent of myopes and 27% of astigmates did not wear glasses, of whom three subjects and two subjects, respectively, were less than 8 years old and therefore at risk of anisometropic or ametropic amblyopia. One subject had epicanthus, one color vision deficiency, and one bilateral congenital cataract. CONCLUSIONS: We conclude that (1) abnormal ophthalmic findings are common in subjects with confirmed FAC syndrome, in particular myopia in those with fetal valproate syndrome; (2) children with FAC syndrome should receive preschool vision testing; (3) preschool vision testing should be considered in all children exposed to anticonvulsants in utero.

Abnormalities, Drug-Induced↗
PubMed2002

Menkes' syndrome: ophthalmic findings.

PURPOSE: To report the prevalence and clinical significance of ocular findings in 20 patients with Menkes' syndrome recruited for a clinical trial at the National Institute of Child Health and Human Development (NICHHD). DESIGN: Retrospective observational case series. PARTICIPANTS: Twenty patients with Menkes' syndrome enrolled in a clinical trial at the NICHHD, who underwent ophthalmic evaluation at the National Eye Institute from 1990 through 1997. METHODS: Review of clinical ophthalmic examination records, photographs, and visual evoked potential recordings. MAIN OUTCOME MEASURES: Prevalence of ophthalmic signs of unusual frequency in patients with Menkes' syndrome. RESULTS: There was a high prevalence of very poor visual acuity (8 patients), myopia at 21 months old or younger (5 of 9 patients this age who underwent cycloplegic refraction), strabismus (11 of 18 patients whose motility was evaluated), blue irides (15 of 16 patients whose iris color was documented), iris stromal hypoplasia and bilateral peripheral transillumination (7 and 3 patients, respectively), peripheral retinal hypopigmentation (7 of 18 patients whose retinal periphery was noted at the initial examination), and aberrant eyelashes (5 patients). CONCLUSIONS: Patients with Menkes' syndrome exhibit a high prevalence of several ocular findings, including some (very poor visual acuity, myopia, strabismus) that may warrant special care. Early ocular examination is thus indicated for patients with Menkes' syndrome, particularly those with mild variants of the disease, whose neurologic status is better and lifespan is longer.

Abnormalities, Multiple↗
PubMed2002

Component dependent risk factors for ocular parameters in Singapore Chinese children.

OBJECTIVE: To examine the risk factors for variations in ocular biometry parameters in Singapore Chinese children, a population with a known high prevalence rate of myopia at an early age. DESIGN: Cross-sectional study. PARTICIPANTS: Children aged 7 to 9 years (n = 1453) from three schools in Singapore. METHODS: The children underwent A scan biometry and cycloplegic autorefraction measurements. Questions were asked regarding number of books read per week, night lighting, and parental myopia. MAIN OUTCOME MEASURES: Axial length, vitreous chamber depth, lens thickness, anterior chamber depth, refraction, and corneal curvature radius measurements were made. RESULTS: After controlling for several factors, the axial lengths were found to be longer and vitreous chambers deeper in children who were older, male, read more than two books per week, or taller, and those who had at least one parent who was myopic. In these models, children who read more than two books per week had axial lengths that were 0.17 mm longer and vitreous chambers that were 0.15 mm deeper compared with children who read two or fewer books per week. Anterior chambers were deeper in males and taller children, whereas corneal curvature was steeper in female, older, and shorter children. CONCLUSIONS: Increases of axial length and vitreous cavity depth were associated with older age, being male, reading more than two books per week, increased height, and parental history of myopia. Of these risk factors, however, neither reading nor parental myopia history were associated with values for anterior chamber depth, corneal curvature, or lens thickness. These findings confirm that conventional risk factors for myopia associated with the vitreous cavity, but suggest that anterior segment parameters such as corneal curvature and lens thickness may be subject to unrelated postnatal growth control mechanisms.

Age Distribution↗
PubMed2002

Conductive keratoplasty for the correction of low to moderate hyperopia: U.S. clinical trial 1-year results on 355 eyes.

OBJECTIVE: To document the 1-year safety, efficacy, and stability results of 355 eyes treated in the multicenter study of conductive keratoplasty (CK) used to correct low to moderate hyperopia. DESIGN: Nonrandomized comparative (self-controlled) trial. PARTICIPANTS: Twenty surgeons at 13 centers performed CK on the eyes of all patients enrolled in a multicenter, 2-year, U.S. phase III clinical trial. Treated eyes had +0.75 to +3.00 diopters (D) of hyperopia and < or =0.75 D of cylinder. Patients were 40 years of age or older. INTERVENTION: Low-energy, high-frequency current was applied directly into the peripheral corneal stroma through a delivery tip inserted at 8 to 32 treatment spots. The number of treatment spots was increased for increasing levels of hyperopia, but the amount of radiofrequency energy remained constant. Emmetropia was intended. All eyes were treated once (there were no retreatments). MAIN OUTCOME MEASURES: Data from 355 eyes with 1 year of follow-up were analyzed for safety and stability, and data from 318 eyes were analyzed for efficacy and predictability, as well as stability and safety. All patients reported on satisfaction and quality of vision after surgery. RESULTS: At 1 year, uncorrected visual acuity was < or =20/20 in 56%, < or =20/25 in 75%, and < or =20/40 in 92% of eyes. The manifest refractive spherical equivalent refraction was within 0.50 D in 63%, within +/-1.00 D in 89%, and within +/-2.00 D in 99%. Seven of 355 eyes lost 2 lines of best spectacle-corrected visual acuity at 1 year, but no eye lost >2 lines. One eye of 355 had induced cylinder of >2.00 D. The cycloplegic refractive spherical equivalent changed a mean of 0.25 +/- 0.50 D between months 3 and 6, 0.11 +/- 0.41 D between months 6 and 9, and 0.11 +/- 0.35 D between months 9 and 12. Refractive stability seemed to be attained by 6 months and remained stable through 12 months. Histology and confocal microscopy showed deep penetration of the treatment into the stroma. Endothelial cell counts were not changed by the treatment. CONCLUSIONS: CK seems to be safe, effective, and stable for correcting low to moderate spherical hyperopia in patients 40 years old or older. Treatment penetration is deep and cylindrical in shape, and it does not damage the corneal endothelium. Uncorrected visual acuity, predictability, and stability are as good as or better than those obtained with other techniques used to correct hyperopia.

Adult↗
PubMed1993

The Casebeer system for predictable keratorefractive surgery. One-year evaluation of 205 consecutive eyes.

PURPOSE: This study documents the results of current radial keratotomy (RK) surgical technology, using the Casebeer keratorefractive system. These results are contrasted to those of the Prospective Evaluation of Radial Keratotomy (PERK) keratorefractive system, developed approximately 12 years ago. METHODS: Two hundred five consecutive surgical procedures were examined, which was the first year of experience with RK for one of the authors (TPW). All procedures fit within the Casebeer nomograms. Enhancement procedures were performed following the Casebeer system nomograms. RESULTS: Follow-up for 100% of patients was achieved. Postoperative cycloplegic refractions yielded an average of +0.27 +/- 0.58 diopters (D) of residual refractive correction (range, -0.88 to +2.50 D). One year postoperatively, 20/25 or better uncorrected visual acuity was achieved in 86% of patients and 20/40 or better uncorrected visual acuity was achieved in 99% of patients. Bothersome but not incapacitating side effects, such as glare, starbursting, and fluctuating vision, have been commonly observed with RK. CONCLUSION: The Casebeer system for keratorefractive surgery, which is easy to learn, can yield an extremely accurate surgical result. The major reason for increased accuracy compared with the PERK system is the surgeon's ability to titrate the primary surgical procedure with enhancement operations. Although RK is by no means a perfect surgical technique, side effects tend to be relatively minimal, and patient satisfaction tends to be extremely high.

Adult↗